Neutrino Hunting in Antarctica

"Extreme Science" -- in the theater

2012-02-17T14:05:00.002-08:00

On February 27th, I will be one of four participants in a presentation on "Extreme Science" - part of Berkeley Labs "Science in the Theater" series, to be held at Berkeley Repertory's theater. It should be an interesting mixture - two scientists who work in extreme environments (Antarctica and Siberia & other places), and two whose work is extreme in other ways. Each of us will speak for 10-12 minutes, and then answer questions. Previous "Science in the Theater" series have featured scientific quartets with similar interests; it will be interesting to see how this works with four people from diverse backgrounds.

Details (time, location, etc.) are available on the Friends of Berkeley Lab website. There is also a nice promo video on youtube.

ARIANNA 2011

2012-01-03T15:36:00.001-08:00

I have been quite remiss about posting to this blog. One of my new years resolutions has been to do better.

Despite the lack of postings, ARIANNA has been moving forward. In November/December, three graduate students from UC Irvine visited the site, and deployed another prototype station. The setup if similar to the current system, but this station has a new waveform digitizer system, based on a new chip from Stuart Kleinfelder. It also has electronics (computer, etc.) that should handle the cold better.

They also rejuvenated the old station. Now, as long as the power holds out, we will have two stations for comparison purposes.

One of the students kept his own blog, at

http://ericcberg.blogspot.com/

It is well worth a read.

-Spencer

The blog photos are back!

2011-12-14T18:13:00.000-08:00

As some of you have pointed out, the photos in my blog disappeared precipitously (and mysteriously). This turned out to be a casualty of Lawrence Berkeley National Laboratory's (LBNL's) adoption of google software. Previously, my blog was linked to my LBNL email address. When LBNL adopted google software, it set up a new superstructure, which required that the blog be associated, at least temporarily, with a different email address. The blog text survived this transfer, but the photos did not.

I have now gone through, and laboriously re-added the photos to the blog, currently with one exception which I will fix later. Although I tried hard, it may be that one or two of the photos different from the original images; since the file names didn't survive the transfer, it is impossible to be sure.

I apologize for the length of time that the blog remained pictureless; it took some time to identify the problem, and even more time to work up the energy to re-create material that disappeared.

ARIANNA 2010 - Part 4 - Finale

2011-08-24T14:07:00.000-07:00

Here is the conclusion of Jordan's account:

And then came the fog. The fog drifted in from the south and obscured the helo pilot's ability to see where he was landing. After several unsuccessful attempts to descend through open patches, the pilot decided to return to McMurdo and try again the next day. Then, we saw from a distance, the helo descend through a patch of fog that had opened. The helo returned, 50 meters off of the ground, and dramatically landed right next to our camp in a whirl of snow and cheers. Although I looked forward to warm food and a hot shower back at the main base, I felt the Antarctic wilderness calling me back. I admired its raw untouched beauty as we ascended through the clouds above the glaciers, and looked back as our experiment disappeared in the distance.

The first flights leaving McMurdo were delayed, and it turned out we'd be spending Christmas in McMurdo. Steve and I had planned on this, and simply enjoyed the food and good company in the mess hall, which had quite a buffet for Christmas dinner. I also took the opportunity to hike to the top of Observation Hill, which looks out over McMurdo and the surrounding ice shelf.

After we drove to Pegasus air field, where our C-17 was supposed to embark for Christchurch, we met several physicists from the CREAM experiment. CREAM (Cosmic Ray Energetics and Mass) is an experiment designed to detect cosmic rays in the upper atmosphere by flying the detector on a balloon. We swapped stories from the field and took pictures. It was a fitting way to end the trip, in the company of fellow cosmic ray Antarctic researchers.

There has been a lot of activity since we returned to the USA. A paper on the results of our analysis of the reflecting properties of the ocean is going to be published in the proceedings of the 2011 International Cosmic Ray Conference. We are also gearing up for next season, and we plan on installing a second prototype station. We've added a new graduate student, Joulien Tatar, who is working on a way to link the two stations together via noiseless wireless communications. We are in the process of fabricating the circuit boards for the next station, which will include a new way of distinguishing the difference between an interesting neutrino-like signal, and radio noise.

Postscript from Spencer: Planning for the 2011 season is underway now.

ARIANNA 2010 - Part 3 - In the Field

2011-08-24T14:00:00.000-07:00

Here is part3 of Jordan's account of the 2010 ARIANNA field season:

In addition to fixing the station, Steve and I also scheduled time to make measurements of certain properties of the ice beneath the detector. Spencer Klein and Thorsten Stezelberger had already calculated the depth of the shelf beneath the prototype using data taken in 2009. They did this by pulsing a radio signal down through the ice, and measuring the time for the signal to return after reflecting. This experiment requires very sensitive equipment, since the signal strength decreases with distance, and we're working with a total path length of over a kilometer. Steve and I repeated this measurement, and got the same answer as Spencer and Thorsten. We would also go on to use that data to measure how much power a radio wave loses as it travels through the Ross Ice Shelf. The key problem in the past was that no one knew how much power the radio wave looses when it reflects off of the ocean beneath the ice shelf.

To study this separately from the effect of the ice, I moved our transmitting equipment to the end of the 1 kilometer flag line we established on the first day of the expedition. I had the help of Leah Biezums, who flew in via helo to relieve Rebekah after the first week. Now we had a path length of one and a half kilometers, and the power loss from the ice would be stronger because of the increased distance the radio signals had to travel through the ice. Presumably, the properties of the reflecting ocean were the same. Thus, by comparing the amount of power received in the signals with different path lengths, but the same reflection properties, we could isolate and study the reflecting properties alone. We've found that the ocean/ice interface acts like a smooth mirror, reflecting a large fraction of the radio signals' power. This bodes well for detecting high energy neutrinos which create radio pulses, because neutrinos propagating downward through the ice shelf will create radio waves that reflect off of the bottom and back up towards the ARIANNA detectors.

As the expedition began to draw towards its close, Steve and I began to perform tasks that would ensure the viability of the detector throughout the rest of the summer and winter. We repositioned the “heartbeat” antenna, which is designed to pulse calibration signals at the prototype detector and tells us certain information about its ability to trigger on neutrinos and determine their direction. We chose a more ideal location based on heartbeat data taken the previous season. I later used this data to show that ARIANNA has the ability to distinguish the time of arrival of a signal in two different sensor antennas to a precision of 100 picoseconds. With Leah's help, I erected the larger, more powerful wind generator and watched as it begun to spin, providing sustainable power to the station which would eventually lead to data being taken further into the Antarctic winter. We began to pack up the gear, both survival and scientific, and awaited our helo extraction.

ARIANNA 2010 Part 2: Arrival in Moore's Bay

2011-08-01T18:29:00.000-07:00

Here is part 2 of the guest post by Jordan Hanson, about the 2010 ARIANNA field season.

The beauty which surrounded us during our helo flight to the detector can only be inadequately described. We flew past windswept mountains covered in dark weather, accompanied by white glistening glaciers beneath. We observed rock formations and islands in the ice shelf that protruded upwards for a thousand feet, such as Minna Bluff. Finally, we passed Mount Discovery and proceeded onto the vast, open Ross Ice Shelf – a flat expanse of pristine snow-covered sea ice over half a kilometer thick. One hundred and twenty kilometers from our departure point, we located our detector.

After we touched down and the rotors of the helo stopped spinning, we began to unload the gear and set up camp. First we established a “cargo line,” a row of bags and tents that allowed us to access individual pieces of equipment easily in an environment in which it can be difficult to maneuver. We also had to scan for crevasses, potentially melted cracks in the ice that can have depths of hundreds of feet. With the help of ground penetrating radar, we were able to trace out a safe area on which we could safely build our camp. I remember it being so windy (in excess of 40 mph from the south) that my hands got numb each time I took them out of my parka pocket to take a bite of my sandwich.

Once we had constructed camp, we began cooking and boiling water to keep warm and get used to living there for two weeks. We had several tents: one for working and the kitchen, three tents for sleeping (Steve, Rebekah, and myself), and a tent which served as an outhouse. We unpacked our scientific gear and began installing it in the work tent. After we created our camp site, it was my job to establish a 1 kilometer flag line to be used in a later experiment. I went with a mountaineer from McMurdo, who examined the output of a ground-penetrating radar unit while I pulled it on a sled. Placing a bamboo flag every 100 meters, we staked out a crevasse-free line 977 meters long. Camp looked like a few yellow dots on a vast, flat white surface, backed by mountains covered with glaciers in the background. After placing the flags, we headed back to base.

I was eager to fix the detector, which had not come online yet since the sun had returned to shine on our solar panels. We had a small wind generator during the previous season, but it turned out not to draw enough power from the wind storms that happen every so often on the ice shelf. Steve injured his back the day we arrived in camp, so he returned to McMurdo for medical treatment while Rebakah mangaged the camp and I saw to the ARIANNA prototype. I had a satellite phone which I used to communicate with Thorsten Stezelberger, who installed the detector originally with Spencer Klein in the 2009-10 season. I noticed that the 12V lead-acid gel battery used to power the detector was cracked, having slightly frozen and expanded. However, it still held charge, and thus we do not expect that this was the problem.

It took us a long time to excavate the electronics box, which was buried in six feet of snow, beneath the metal rig that supports the solar cells. Once we had it in the tent, I used a Honda generator and a DC power source to power the electronics, while I checked each electronics component individually to located the problems. Before replacing anything, I extracted the data from the previous season and saved it on one of our computers and in other places. There was brand new event data that we had never seen before, since our station ran even after the wireless communications were removed. I replaced the CPU battery backup, which had lost its charge after so many months without power and in -30 degrees Celsius temperatures. I replaced the CPU itself, which appeared to be non-functional, and the analogue to digital converter (ADC) as well. After I fixed those components, I checked to see if the Iridium satellite modem began to draw current. I eventually figured out that the network settings such as port assignments had been lost and/or changed for certain systems upon shutdown, and after fixing all of that, the satellite modem began sending data North. Fixing the current prototype was a big victory for us, because it allowed us to take data during the 2010-11 season at a lower threshold, since man-made noise sources from the wireless communications equipment had been found and eliminated. In addition, I built and installed a taller, more powerful wind generator that allowed us to take data further into the winter while the sun dipped below the horizon.

ARIANNA 2010: The Journey to Moore's Bay

2011-07-27T16:05:00.000-07:00

I have been remiss about posting about ARIANNA, in particular on the 2010/11 field season. UC Irvine Prof. Steve Barwick and graduate student Jordan Hanson travelled back to the site in December, 2009. Jordan sent me some pictures and text describing that trip. Because of the length, it is divided into four posts. Here is part 1 of Jordans account:

The Journey to Moore's Bay, 2010

My name is Jordan Hanson, and I am a graduate student researcher at UC Irvine working for the ARIANNA collaboration. My research focuses on the viability of ARIANNA to detect high energy neutrinos in the background-free environment of Moore's Bay, in Western Antarctica. My adviser, Steve Barwick, and I, travelled to Antarctica in the winter of 2010 to revive the prototype station and make measurements of the properties of the ice beneath it.

Every long journey begins with a first step. Ours was to travel to Christchurch, New Zealand, which is the gateway city that coordinates flights to McMurdo Station, located on Ross Island in the middle of the Ross Ice Shelf. Christchurch hosts the United States Antarctic Program (USAP) and the clothing distribution center (CDC). Upon our arrival, Steve and I met with USAP personnel to gather our extreme cold weather (ECW) gear, necessary for landing on an ice shelf at almost 80 degrees South latitude. While staying at the Windsor Bed and Breakfast in Christchurch, we encountered other scientists traveling to the Antarctic continent to perform the season's research. There were geologists, climatologists, astronomers, and physicists like us. We even met several scientists in our field of high energy neutrino astronomy, working for the IceCube project (see recent posts on this blog). Specifically, we met a team led by Per-Olof Hulth, of the University of Stockholm. I had an interesting conversation with Reina Maruyama about DM-Ice, a project related to IceCube focusing on direct detection of dark matter.

On the morning of our departure, we had coffee with Vladimir Papitashvili, the director of the Aeronomy and Astrophysical Sciences Program (Office of Polar Programs) at the National Science Foundation. I learned about many other experiments like ours taking place around the Antarctic continent. When it was time to leave, we all boarded the bus to the C-17 and were escorted onto the aircraft by military personnel.

Although the details of McMurdo station and how it operates have been covered in previous posts, I'll recount our experiences briefly. We landed on the Ross Ice Shelf, near the southern tip of Ross Island, where there is a station called McMurdo station. In the summer months, it is home to over a thousand individuals, and it forms a scientific community complete with technical and logistical support staff. The dedication and hard work of these support staffs cannot be understated. Specifically, Steve and I worked with Jessy Jenkins, our point of contact, whose job it was to coordinate the accumulation of survival gear, our technical equipment, food and supplies, fuel, and helicopters necessary for accomplishing our mission. Rebekah Davis travelled with us initially to the field, to manage our camp and assist with things like tent building and radio communications. After assembling our gear and coordinating with helo-ops, we were ready to launch into the wilderness. We were accompanied by wireless communications technicians, led by Bill Nesbit, whose goal it was to establish wireless internet at the site of our prototype station.

We're done - IceCube is finished

2011-01-04T16:13:00.000-08:00

After 7 construction seasons, IceCube is finally complete!

Construction ended quietly on Saturday, Dec. 18th(New Zealand date), as the last string was lowered into the ice, completing the 86-string, 5,160 optical module array. This was the last of 7 strings deployed in December; this was a very short season compared with the last two seasons, when 19 and 20 strings were deployed, respectively. Work at the Pole has now turned toward packing up the drill for long-term storage, upgrading the computer system on the surface, and sending now-surplus material North.

The occassion was celebrated by press-releases galore:

Several groups have issued press releases to note the occasion:

From the NSF and University of Wisconsin:

http://www.nsf.gov/news/news_summ.jsp?cntn_id=118236&org=NSF&from=news

From LBNL:

http://www.physorg.com/news/2010-12-icecube-world-largest-neutrino-observatory.html

From DESY (in German):

http://www.desy.de/e428/e548/e4802/e87334/e105250/index_ger.html

There was also a modicum of press coverage - check out google or google news for the latest.

A belated Happy Holidays to everyone.

The Coming Antarctic Season

2010-10-29T16:48:00.001-07:00

Preparation for the coming Antarctic field season are in full swing, in both IceCube and ARIANNA.

On ARIANNA, Steve Barwick and Jordan Hanson visited LBNL last week, to learn about the station hardware and software. They will be going out to Moore's Bay in early December, to recondition the station, and perform a number of calibration measurements. These calibrations should allow us to set a limit on the flux of ultra-high energy neutrinos. Although the limit from one station will not be very stringent, carrying out the analysis through to the end is a good way to convince ourselves (and peer reviewers) that we understand the system thoroughly.

Unfortunately, even though the sun is now above the horizon 24 hours/day, the station has not yet 'woken up' from the Antarctic winter hiatus. The most likely possibility (also the most optimistic) is that the battery cracked during the winter. There are some good reasons to believe this - the charge controller left it in a discharged state, and batteries are known to be a problem at low temperatures. Alternately, maybe the solar panels are still coated with snow, or, more likely, the Iridium antenna or some other part broke. The worst case scenario would be if the station failed mechanically, and that the solar panels, etc. will be strewn across the Ice Shelf, buried under a winters accumulation of snow.

The first IceCube personnel are already in New Zealand, waiting for flights to McMurdo station. The plan for IceCube is to drill the final seven holes and deploy strings in them, and then prepare the drilling system for hibernation. In addition, two of the strings will include sodium-iodide crystals which will be used to look for dark matter. Although the IceCube project included funding to disassemble the drilling system and move it North (to avoid leaving any junk in Antarctica), the drill has many future applications. In particular, if the dark matter prototype works well, then additional crystals may be deployed, in special background-free pressure vessels.

Public Lecture

2010-08-25T13:16:00.001-07:00

I gave a public "Sciece@Cal" lecture last Saturday, on "Neutrino Astronomy in Antarctica. I talked about why we want to do neutrino astronomy, and about IceCube and ARIANNA.

Science@Cal is a monthly series of Saturday lectures, intended for anybody who is interested, on various subjects. It was an interesting experience, attracting attendees with a wide range of backgrounds, and, clearly, based on the questions, a wide range of background knowledge.

A video of the talk is available , and the a pdf file with the slides is posted here.

Cosmic Rays and their effect on earth

2010-08-18T19:10:00.000-07:00

One interesting 'practical application' of cosmic-rays is in how they may affect life on Earth.

The obvious effect is that cosmic-rays are responsible for a good chunk of the background radiation that we experience on earth (the Earth itself is responsible for most of the rest, in the form of natural radon gas, etc.).

Of course, a dramatic short-term increase in the background radiation is dangerous. An overly nearby supernovae or other high-energy astrophysical events would be deadly (but very, very rare); it has been speculated that they may be responsible for occasional mass extinctions.

The long-term effect of lower doses of radiation, as from cosmic-rays is less clear. Cells contain repair mechanisms which can repair chromosome damage if it occurs slowly enough, and experimental studies of low levels of radiation have not found an increase in mutations. But, increased radiation level could cause increased mutation rates, and it has even been speculated that moderately nearby supernovae could have aided human evolution. Of course, in the shorter term, most mutations are not beneficial. It has been argued that the increase in ground-level radiation during reversals of the Earth's magnetic field could lead to increased mutation, and possibly, even to extinctions.

These supernovae leave geochemical 'footprints' on earth. These footprints can be seen in the form of thin layers of otherwise rare isotopes and an increase in carbon-14 abundance. The changing production rate greatly complicates the use of carbon-14 for dating, and elaborate calibration curves have been needed to relate the measured carbon-14 abundance in artifacts with the actual age.

Of course, this is mostly speculation. Interesting and important speculation, but still speculation.

Neutrino 2010 - conference report

2010-06-24T11:58:00.000-07:00

Neutrino 2010 was an interesting conference. There were no earthshaking new results, but there was steady progress on many fronts.

The most interesting new results came from the MINOS and MiniBoone experiments. These are both detectors that observe neutrinos produced by an accelerator at Fermilab, near Chicago. Both experiments are studying neutrino oscillations, whereby a neutrino produced with one flavor (electron, muon or tau neutrino) oscillates as it travels from the accelerator to the detector.

MINOS has observed a possible difference between how neutrinos and antineutrinos oscillate. If correct, this would be very surprising, signalling a big difference between matter and antimatter. Although this result got significant publicity, apparently due to a Fermilab press release, the difference was not statistically large, and almost everyone at the conference was happy to treat it as a likely statistical fluctuation, pending more data. The other anomaly, from MiniBoone is harder to characterize, but is also likely a statistical fluctuation.

Two other popular topics were searches for neutrinoless double beta decay, and progress toward enormous (100,000-500,000 ton detector) next generation detectors.

In neutrinoless double beta decay, a nucleus changes it's atomic number by two (i.e. germanium decays to selenium, or xenon to barium), emitting two electrons and no neutrinos. This is only possible if a neutrino can act as it's own antiparticle, so this would be a major discovery. If this process occurs, it is very rare, with a half live of well over 10**20 (10 to the 20th power) years. So, these experiments must monitor large quantities (typically 100 pounds to 1 ton) of material for long periods, with a sensitivity to observe even a handful of decays. This is not easy. We heard 6 talks on neutrinoless double beta decay, discussing a wide variety of possible methods.

Over the past two years, there has been considerable progress toward a very large detector to make precision measurements of neutrino oscillations. The U.S. version would be located in DUSEL, the Deep Underground Science and Engineering Laboratory, which is proposed to be built in an old gold mine in South Dakota. The Japanese are also pursuing a similar project on an island between Japan and South Korea (the location is chosen to be the optimal distance from the Japan Hadron Facility accelerator), and the Europeans are considering several projects at diverse sites.

My talk, on radiodetection of neutrinos, went well, and seemed well received. It was a tough talk to prepare, since I had to introduce the concept, and also cover experiments looking for neutrino interactions in the moon, and two types of experiments looking for neutrino interactions in Antarctic ice (including, of course, ARIANNA). I also had a chance to talk to a number of people who are interested in ARIANNA.

Although Athens is a very interesting city, June is not the optimal time for a visit. They were having a heat wave during the conference, and temperatures were in the high 90's or low 100's (depending on which source you looked at), and it was also fairly humid. Worse, there was a 3-day metro (subway) strike during the conference. This was quite disruptive, since many of us were taking the metro between our hotels and the conference center. Of course, during the strike, the busses were jammed past capacity, and taxis were hard to get.

This strikes was not an isolated incident; more strikes are planned to protest government cutbacks due to the budget deficit and the economic conditions imposed by the European/IMF bailout. The threat of strikes has trimmed the tourist trade (it is down about 15% according to what I've read), and Athens seemed less crowded than usual. My hotel was not overly full, and a fair fraction of the residents were neutrino physicists. My flight to Greece was half empty, and there seemed to be a number of parked Olympic Air planes at the Athens airport.

Neutrino 2010

2010-06-11T15:18:00.001-07:00

It is now June; school is getting out, and the summer conference season is starting. The big conference for neutrino physicists, Neutrino 2010 (it's held every 2 years) is next week, in Athens, Greece. About 530 neutrino physicists will gather for a week, to hear the latest results on everything neutrinos. Talks will cover a results from accelerators (Fermilab, CERN...) and non-accelerator experiments, along with the latest theory.

One hot topics is neutrino oscillations, whereby a neutrino from one flavor (like an electron neutrino) oscillates, over time turning into another flavor, like a muon neutrino. There are three different flavors, connected by three different mixing angles, which give a neutrinos propensity to turn into a different flavor. The three flavors have slightly different masses; the mass differences control how long the conversion takes. There is also a phase angle which, if non-zero, would allow charge-parity (CP) violation in neutrinos. This might help explain why the universe is all matter, with no visible antimatter. One way to study this is to shoot
a beam of neutrinos from an accelerator to a distant detector, and measure the oscillation probability. Another way to study oscillations is to use naturally occurring neutrinos. Neutrinos produced by nuclear reactions in the sun have plenty of time to oscillate before arriving at the earth; this is how neutrino oscillations were initially discovered. Or, one can use neutrinos produced in cosmic-ray air showers, which may oscillate as they pass through the earth on their way to a detector like IceCube.

A number of non-accelerator experiment are looking for a process called neutrinoless double beta decay, whereby an atomic nucleus decays, producing two electrons; the nuclear charge changes by two. For example, ^36Germanium decays into ^36Selenium, plus two neutrinos. This process can only happen if a neutrino is something called a "Majorana particle" which means that it is it's own antiparticle. In any case, the half-life for this process must be very long, well over 10^{22} years, so, one need a very large chunk of germanium to study this.

Neutrino astrophysics is also represented at the conference, with a couple of sessions including talks on high-energy astrophysical neutrinos. I will be giving an overview talk on radio-detection of neutrinos, covering ~ half a dozen experiments, including ARIANNA. It was a challenge to squeeze this all into a 15 + 5 minute (15 to speak, 5 for questions) talk.

I'm not looking forward to the long plane-flight to Athens; this will occupy a good chunk of the weekend.

I will try to post more frequently during the conference, both on conference life, and on new results.

A paper!

2010-06-02T23:08:00.000-07:00

It's been a while since I've posted. The main reason is that I've been busy. One of the things that I've been doing is writing a scientific paper describing the prototype hardware, and the results of our season.

The paper is finally done, and submitted to "Nuclear Instruments and Methods," a journal that publishes papers on instrumentation for nuclear, particle and astro-physics. There it will be peer reviewed by anonymous referees (most likely 2 reviewers), who will recommend whether it should be published or not. Most likely, they will recommend acceptance, but they will also most likely suggest some ways to improve the paper. At the same time, the preprint version was posted to the Cornell preprint server, as number 1005.5193; click on 'PDF' on the upper right to get the paper text.

It may not be obvious, but writing any scientific paper is a lot of work, even a relatively 'simple' paper like this one. Besides the text, there are figures (graphs, plots, etc) which can take a lot of work to make. There are also many numbers to be checked. When you actually sit down to write a paper, you are forcibly confronted with all of the pesky details that you've successfully avoided over the past few months.

This was true even though we made some specific decisions to speed things up. For example, we do not discuss our on-going data analyses. These are interesting, but there is a lot to do before we're ready to publish these analyses.

The major 'result' in this paper is a measurement of the ice thickness at our site: 572 +/- 6 m. In principle, this is a simple calculation - take the round-trip travel time for the radio waves we bounced off the ice-water interface, and divide by twice (for travel in both directions) the speed of light. Unfortunately, nothing is that simple. In any material, the radio waves travel slower than Einstein's famous unchanging speed of light - that invariance only holds in a vacuum. The reason is that the radio waves interact with the medium. One way to think about this is to imagine the radio waves scattering off the atoms in the ice, so they don't travel in a direct, straight line. The speed of the waves depends on the snow/ice density throughout the trip. The top 75 meters of snow/ice (the 'firn') changes gradually from snow (density 40% of that of ice) at the top, to pure ice about 75 m down. After trying to model this myself, I consulted with colleagues and poked around in the library (now mostly on the internet), and finally found a review written by two real professionals who bounce radio waves through Antarctic ice sheets for a living. Suddenly, it was simple. Their article even included different density profiles for different places in Antarctica, along with estimates of the consequent uncertainty.

Another thing that took some time was getting comments from the other authors, and responding to them. Our paper has 7 authors from 3 institutions; everyone who contributed to the experiment and wanted to be an author. We also got some comments from non-authors, mostly people who were involved less directly.

Most of the comments were good, and strengthened the paper. Of course, a good suggestion (e.g. improve this figure by...) takes longer to implement than a bad idea that can be rejected. And, there is always discussion about expanding the scope of the paper.

With larger groups,dealing with comments can get sticky, especially if people disagree on what should or should not go into the paper (that wasn't the case for us). Large collaborations, like IceCube have formal policies and procedures for internally reviewing papers, collecting and mediating over comments from collaborators, etc.

In the end, I think that the paper came out pretty well. But I may be biased.

Results from ANITA

2010-03-18T13:37:00.000-07:00

The Antarctic Impulsive Transient Antenna (ANITA) experiment has just published their results from their second flight. Like ARIANNA, ANITA searches for radio waves from extra-terrestrial neutrino interactions. However, instead of embedding their antennae in the ice, the antennae are mounted on a long-duration high-altitude balloon. These balloons are launched from McMurdo Station, where the prevailing winds push them in a circle around Antarctica; the data they report is from a 31 day flight in December, 2008, at an altitude of about 35 km (113,000 feet). The picture shows ANITAs 32 antennae, which look for radio waves from neutrino interactions in the ice out to the horizon (up to 650 km away).

After a series of cuts to remove background events, they are left with two events, against an estimated background of 1 +/- 0.4 events - no statistically significant signal is observed. They set a limit on the possible flux of extra-terrestrial neutrinos which is considerably more restrictive than previous studies. Their limit is just starting to constrain models of GZK neutrino production. Clearly, a more sensitive experiment is needed.

ANITAs ability to observe a large chunk of Antarctica in one shot is a big plus. However, balloons have a limited observation time. And, the up-to-650 km separation between the source and the detector inevitably means that ANITA can only see the most energetic neutrino interactions. By placing our antennae directly in the Antarctic ice, ARIANNA will be able to see a wider range of neutrino energies, covering most of the GZK energy range.

The IceCube Construction Season

2010-02-16T18:16:00.000-08:00

ARIANNA is not the only experiment with a successful construction season. IceCube also had a great season. They deployed 20 strings into the South Pole ice (beating their goal), and finished a week early.

This is a very impressive achievement. 2500 meter deep (1 1/2 miles), 60 cm (about 2 feet) diameter holes are drilled in the ice, and strings (cables) of 60 optical modules are lowered into the hole. The photo above shows the drill head, which is moved from hole to hole. The holes are drilled with a water jet that shoots 200 gallons/minute of water at 88 degrees (Centrigrade) through a 1.8 cm (about 3/4 inch) diameter nozzle at a pressure of 200 pounds per square inch.
Drilling each hole takes about 40 hours, plus another 12 hours for deploying the strings. This photo shows a DOM being lowered down the hole.

LBNL postdoc Lisa Gerhardt has just returned from the South Pole, where she worked on testing the deployed strings. She kept a nice blog. Laura Gladstone (U Wisconsin) also kept a blog of her trip. There are accounts of past trips (with tons of pictures) elsewhere. In view of all of these other accounts, I will be brief and end here.

[n.b. These two photos are from my 2006 trip]

Global Warming in Antarctica?

2010-02-08T14:55:00.000-08:00

Several people have asked me about the 'warm' weather that I experienced, and whether this was due to global warming. Others have asked about my photos of liquid water (e. g. above). Is this due to global warming? Did I see global warming in Antarctica?

I've hesitated to answer these questions here, because these are not simple ones. However, with the caveat that I am NOT an expert on climatology, let me tell you what I know.

The evidence for global warming is very clear.

The carbon dioxide levels in the atmosphere have risen to levels far beyond anything seen at least since the last Ice Age, and very probably for the last 400,00 years. For the purposes of considering the future of humanity, I don't think that we need to go any further back. This increase is clearly due to human activity.

Global temperatures are rising, and the last 50 years have been the warmest in centuries. There are many many places where one can compare photos of glaciers taken 50-100 years ago with recent photos; the differences are dramatic. A quick google search found examples from Glacier National Park, elsewhere in North America , and even from Africa's Mt. Kilamanjaro. One can debate temperature trends, the effect of heat islands, etc., but it is clear that these glaciers have formed over long periods, and are now rapidly disappearing. Further, they are far from cities or other local heat sources.

These examples are all from the Northern hemisphere or equatorial region (Mt. Kilamanjaro is 3 degrees south of the Equator). In Antarctica, the evidence is less dramatic, but there are clear signs of thinning glaciers.

Of course, one can find contrary evidence. In McMurdo, I heard a talk about exploring the dry valleys; the speaker pointed out one location where there is now apparently much more ice than in 1904, when Scott visited the site. On balance, however, there is much more evidence for global warming than against it.

That said, what I observed was not evidence of glacial warming. The temperatures during my visit were well within the expected range. The water pools were not anomalies; the snow around McMurdo always melts on hot summer days, forming small freshwater pools. Global warming is real, but one needs careful, long-term study to observe the effects - one visit to an area is not enough.

Anybody who wants to learn more about global warming should visit the website of the International Panel on Climate Change (IPCC). Their reports (available on the website) discuss an enormous volume of climatological data drawn from many sources. Notwithstanding an occasional gaffe, their carefully worded conclusions represent the views of the vast majority of climate scientists.

Looking at the Data

2010-02-04T14:27:00.000-08:00

It's been several weeks since I posted. The major reason for the gap is that my father passed away in early January, and it's been tough. I'm very glad that this didn't happen while I was in Antarctica.

In the past few weeks, we (the royal we - mostly, it has been Steve Barwick, Jordan Hanson, Lisa Gerhardt and Ryan Nichol) have been looking at the data, which is flowing smoothly through the internet link. Mostly, things look very good, and the station continues to work well. This data falls into two classes: housekeeping data, relating to station performance, and triggered data, collected when the antennae see something).

Lisa Gerhardt posted some of the early (through early January) housekeeping data on the web Please remember that not all of this data has been calibrated yet. The temperatures in particular seem low. That said, a few trends are clear. One is that the wind kicked up shortly after we left (starting around Dec. 26th), and again in early January. So, there may be hope for the wind generator. A second is that the diurnal (day-night) variations are present, but small.

The antenna data is harder to describe here, but we are also making progress. Some background might be helpful here. We collect data (and call it an event) whenever the signals on two of the four antennae are above an adjustable threshold. These signals could come from background noise, natural sources, or man-made sources. When a trigger occurs, we record the data for each antenna for 60 nanoseconds (billionths of a second). This may seem like a short interval, but a real neutrino event should produce a pulse that is less than a few nanoseconds long.

One thing that jumped out early was that the trigger rate was partly periodic. We saw triggers every 60 seconds, as expected, These are the 'heartbeat' pulses that we create to check the detector. But, we also see other, unexpected periodic signals. Sometimes, triggers are separated by almost exactly 6 seconds - pretty clearly, a man-made source. The rate of these pairs varies over 24 hours, and we suspect that it comes from the switching power supplies that power the internet hardware. If so, this will disappear when the internet equipment is removed. We also see other events not related to these periodic signals. These might be 'thermal noise' the irreducible background associated with random noise due to molecular motion, etc. This thermal noise provides the 'natural' limit to detector performance. There are ways to reduce it (better antenna, lower noise preamplifier, etc.), but this thermal noise limit is our immediate goal.

Home

2010-01-07T16:27:00.000-08:00

I made it home in 2009, but only barely, arriving at SFO in the early afternoon of Dec. 31st.

The days of waiting for the C-17 were also days of snow, which was beautiful, but limited our outdoor opportunities. The picture above is actually in color! The snow also caused a 24 hour flight delay, from Dec. 29th to Dec. 30th.

The 30th was sunny, which was doubly fortunate because we had to wait outside while the plane landed and then while they unloaded the incoming cargo and loaded the outgoing. The flight was fairly quiet - there were only about 20 of us. The cargo load was also light - my seat had a view of a large hydraulic jack, used, per the stencil, to raise airplane noses. I'm not sure what it was doing in Antarctica, or why it rated air cargo back.

One nice thing about the wait was that we got to see both the C-17 and a Basler land. A Basler is a re-engined, updated DC-3 - a 60+ year old airframe from a 75 year old design! These are the mid-sized transports, between the smaller "Twin Otters" and the larger LC-130's.

We got back to Christchurch around 8 pm that evening, leaving just enough time for dinner and a nights sleep before catching an 8:40 am flight to Auckland. Unfortunately, there was no time for another visit to the botanical garden.

Auckland was a rough return to civilization. First, there was a 5-hour layover. This was followed by an introduction to post-Dec-25th airport security. After the metal detector and X-ray machines, we were frisked and our carry-on luggage was minutely inspected. Quite a contrast from the -17, where the security check was a reminder not to pack anything sharp in your carry-on luggage.

Now that the trip is over, I will post less frequently to the blog. I have a few more trip-related posts, but, in the longer term I want to talk about how our data analysis is going, what we've learned from ARIANNA, and how it fits into the wider world.

Christmas in McMurdo

2009-12-29T13:05:00.000-08:00

The guest post seems to have fallen through, so I’ll write a bit about Christmas here. It’s a big deal here - a 2-day weekend (the normal RPSC (Raytheon Polar Services Corp.) workweek is 6 days – 54 hours). It started on Dec. 24th, with a big party in the VMF (Vehicle Maintenance Facility), with food and drinks, a slideshow of contributed family photos, some dancing and lots of talking. Plus a chance to visit with Santa, on his sleigh (below; it's very rare to see a Santas sleigh that is actually designed for the North Pole). All in a cavernous building usually used to repair heavy machinery. Or course, there was plenty of snow outside.

On Christmas Day, the main event was dinner, served in 3 shifts (3 pm, 5 pm and 7 pm). The dining crew pulled out all the stops – roast duck, prime rib with horseradish sauce, and lobster tails in herbed butter. Thorsten and I were invited to eat in the BFC (“Berg Field Camp,” also known by residents as “Building Full of Chicks”, for the gender of the people who work there). It was nice to eat with a smaller crowd (~ 25 people, again from helicopter pilots to mountaineers, even if it did mean require carrying our plates of food through the sub-freezing outdoors.
After dinner, we all walked over to MAAG (McMurdo Alternative Art Gallery), which I discussed in the last post. It was a nice evening, even for someone who doesn’t celebrate Christmas.

Waiting for Godot (the C-17)

2009-12-28T00:51:00.001-08:00

The past few days in McMurdo have been largely a waiting period, waiting for the next flight out, on Dec. 29th. The 6-day gap between flights is partly because of Christmas, which is a big holiday here, with a party, a festive dinner and two days off work. The days were Friday and Saturday (the 25th and 26th), with Sunday a normal work day. But, Sunday isn't a normal work day for the Air Force. Ergo, a long gap between flights.

Anyway, I'm working on a special guest post on "Christmas in McMurdo" from a long-time resident. In the meantime, here is a picture from "MAAG," McMurdo Alternative Art Gallery, which was also on the 25th. The name is actually a pretty good description of the event; there was a wide variety of art on display, plus some music and a juggler. Longtime IceCubers will recognize P. J. Charpentier on the violin, above. The picture below shows one local organization; more details are available here

Another interesting exhibit was a room sized camera obscura (pinhole camera) a darkened room with a single hole; the outside was bright enough to project an upside down image of most of McMurdo.

Otherwise, we have been collecting data with the station, filling out various forms, including a detailed environmental survey and starting to work on a journal article about the station.

It has been interesting to see how my body has adapted to the cold. Right now, it is 27 degrees (Fahrenheit), and very lightly snowing, and I'm comfortably walking around in a long sleeve shirt and fleece jacket, jeans and sneakers and wool socks. Three weeks ago, I would have been wearing way more clothes.

McMurdo Station

2009-12-24T16:27:00.000-08:00

I should probably say a little about McMurdo station, especially since I will be here for several days, waiting for the next flight out. It is a very interesting place, with a summer population currently about 1100, and about 200+ people who winter over.

As you can see from the picture (taken from "Ob Hill") McMurdo is mostly a logistics base, supporting scientific expeditions elswhere in Antarctica. Nearby sites include the dry valleys (one place I'd love to visit is "Blood Falls"), glaciers, the Antarctic mountains and the edge of the ice shelf (including penguin research). McMurdo also support expeditions further afield, including the South Pole Station. The WAIS (West Antarctic Ice Sheet) Divide drilling project is a multi-year effort to drill 3400 meter deep ice cores to study the climate over the past 100,00 years. This is a key effort in learning how climate has evolved over time. And, of course, McMurdo supports the South Pole, including IceCube, which is a major effort there, and probably the biggest project on the continent.

So, most of what goes on here involves logistics - shipping supplies to these camps via a variety of helicopters and aircraft, and providing temporary storage facilities. There are also some scientific laboratories which are mostly used for "local" studies around McMurdo, including studies of sea life under the ice.

Since "supplies" includes everything from various types of fuel to mountaineering equipment to camping gear and scientific equipment, there is a pretty wide range of activities here.

One neat thing about the place is being able to meet people from a huge range of backgrounds. Today (Friday), I ate brunch in the galley (below) with some people from the Army Corps of Engineers, studying drainage issues around McMurdo, and a Catholic priest from New Zealand (here as a chaplain). I've also talked with heavy equipment repairman, helicopter and Twin Otter pilots and mechanics, a handful of carpenters in the New Zealand Army, and a woman studying penguins. There are also groups from the U.S. Air Force and Air National Guards, flying the LC-130s and C-17s.

Most of Mcmurdo consists of various types of storage yards and motor pools, and dormitory buildings (many of the buildings that look like barracks). There is also a kitchen and galley (this accounts for about 100 of the people here), a hospital, library, gym, bowling alley (apparently non-functional), small store, post office, chapel, coffee house and bar. Most of the 'recreational' activities operate very limited hours. Since many people work the night shift, some recreational activities are scheduled for the early morning, to accommodate them.

Our Stuff Returns

2009-12-24T16:13:00.000-08:00

Thursday. Our sling load came home today, on (todays) schedule. The top photo shows the sling load being deposited on the helipad.

Unloading was quick; the bottom photo shows it caught in a traffic jam on the way to BFC, where we will unpack it and send the scientific stuff North. Our stuff is the wooden box on the frontloader, plus the load in the stake truck behind it.

I should probably also mention that the station continues to communicate, and we are taking data continuously. The next step is to get a more serious data analysis effort going.

We go

2009-12-23T01:18:00.000-08:00

Wednesday morning. The third time is a charm. At our 8 am call to Helo Ops, we learn that, even though we are scheduled for the afternoon, they are launching in an hour (9 am), and we should be ready. Although they don't say this, they are making a special effort to get us out today.

This is very welcome news on many fronts, especially as we contemplate our dwindling food supply. Most of what we have left is quasi-emergency rations - a variety of freeze-dried foods that are definitely not like Mom used to make.

That said, here's no way that we can take down camp in an hour, much less build a sling load. Fortunately, they realize this, and the helo will wait while the Josh (the helo tech) leads us through building the slings. This is much appreciated, on many fronts.

By around 9:45, as we are still frantically trying to unbury the "deadman" anchors, break the ice away from the sides of the tens, and pack everything, neatly divided for the helicopter and the sling load), the helo is on the radio

They are approaching, but warn us that weather conditions are not great - it is cloudy, so surface definition is not great and a landing is not assured. This instantly brings work to a standstill - it would not be fun to set up camp again.

It makes one approach, decides the weather is OK, and comes back to land. This time, it spends what seems like a considerable time (at least many seconds) hovering just a few feet off the ground, while we lie on our bags, to keep things from blowing away. Finally, it settles down. Although the photo above is from when the sling load was delivered, it's a pretty good representation of things.

From there, it's all uphill. It takes another hour and a quarter to pack up our gear and make the sling load. Because of the weather, they will not pick up the sling load today.

Then, we climbed aboard and take off and watch the station recede into the distance, obscured by clouds of snow blown up by the helicopter rotors.

On our arrival, we were met by a truck which ferried us and our gear up to Berg Field Camp. At this point, it was noon, and the galley was serving lunch for another hour. Since there were some things that absolutely had to be done, this left us with a dilemma: showers first, and risk missing lunch, or lunch? My apologies to anyone who sat near us during lunch.

Coming back to McMurdo has required some adjustments. Besides the masses of people, there are the conveniences - flush toilets, sinks with running water, rooms that can be dark, etc. It's nice to be able to be indoors again.

We stay ... and stay

2009-12-21T20:49:00.000-08:00

It's Tuesday afternoon, and we're still here. Shortly after my last posting, Helo Ops threw in the towel for the day - the weather wasn't getting any better.

Today was the same story - calls every few hours, before finally calling things off. The weather was better than yesterday, but not enough better. The photo above, taken around 6 pm, shows the pass that the helicopter would have to fly over, with lots of clouds. This is worse than it was during the day, but not a lot worse.

So, we spend the day taking it easy, waiting for the call to action to disassemble camp. All of our science gear is well buried; we're collecting data, but can't do any more fiddling.

Tomorrow for sure. We hope.

Do we stay or do we go?

2009-12-20T16:35:00.000-08:00

Monday. Today we are scheduled to return to McMurdo. We got up early to have time to take down camp and pack the sling load. However, although the weather here is pretty good - around freezing and windless, with high clouds, Minna Bluff appears socked in, so we wait a while and call Helo Ops, to ask about the prospects for getting out. They say that it is snowing in McMurdo, and we should call back at 10:00. At 10:00, they suggest calling back at noon, and at noon, it becomes 2:00. Even though the helicopters aren't flying, the schedule has freed up, so it might still be possible to get out. So, we're waiting for the 2:00 call now.

Even though we have plenty of food and fuel, and the weather is comfortable, it would be very nice to get back today. Stay tuned.

Finishing Up

2009-12-20T00:55:00.001-08:00

Sunday. Today is our last full day here - the helos are supposed to arrive tomorrow afternoon to pull both us and our stuff out. We will leave on the Kiwi (Scott Base - New Zealand) helicopter.

We spent most of today doing last-minute things with the station - placing the temperature sensors, burying the station box and antenna cables, etc. We decided to deploy the '5th' antenna about 15 feet from the station, connected to the 'heartbeat' transmitter. This transmitter will send out signals at the beginning of a run, showing us that the antennae, etc. are working, and providing a reasonably stable (we hope) calibration beacon.

We also packed up all of our 'science' cargo - our tools and other returnables. Tomorrow, after breakfast, we will take down the tent and pack up camp before the helos arrive. One interesting part of this will be assembling the sling loads. There are tricks that we need to know - the bottom load should be heavier, with the heavier stuff goes in the bottom center of the sling - yet another thing I didn't learn in grad school. Although we took pictures of the load as-delivered, none of us have any experience with this - it should be interesting. Fortunately, the helo tech will check it before picking it up.

Dinner was Pad Thai. For dessert, we had vanilla 'pudding pops' - the good kind of yellow snow. You make a depression in the snow and pour in pudding, with a stick (we used our titanium sporks for this), and wait for the pudding to freeze. The pudding also diffused into the snow, making the edges more like a snow cone than frozen pudding. They were good, but they would have been a lot better if it were 60 degrees warmer outside.

Oh yes. Today's vocabulary word is "hockling" - when a rope gets twisted forming a knob. - from the instructions that came with our 1/4" rope.

Camp Life

2009-12-18T15:47:00.000-08:00

I haven’t posted much in the past few days because camp life has settled into a routine, and there is less of interest to report. We get up in the morning, have breakfast, work on the station or make physics measurements, eat lunch, work more, eat dinner, and then usually work more.

Breakfast is usually eggs and hash browns or cereal. Lunch has been soup and sandwiches or gardenburgers, and dinner has varied a lot. Martha has been doing most of the cooking (and the food has been excellent), in addition to melting snow into water. Although our propane stove puts out a lot of heat, it takes a lot of energy to melt snow and this chore takes an hour or two each day.

Martha and Thorsten are both vegetarians (including some fish), and it is easier if we all eat the same thing, so I’ve been eating vegetarian. However, we did bring two ‘steaks’ (I use that term loosely), and Martha made one for me on Thursday evening. Unfortunately, it badly smoked up the tent – I don’t think that we’ll do that again.

The weather continues to be good. On Friday, it was very cloudy, but only about 10 degrees colder than previously. In the morning, it was windy for a while - we saw gusts up to about 15 miles/hour, but they slowed down quickly.

We are beginning to think about the ‘end game’ – making sure that everything critical is done before we leave. We don’t have time to do everything in the detail that we’d like; we are trying to look at everything at least a little bit. As part of finishing up, we buried the antennae yesterday, and also made measurements of the antennae locations.

Work on the station has progressed. It is now fully operational, and we are doing discriminator scans to measure the ambient noise levels. One significant question is how much the radio emission from the wireless internet is seen by the station. To answer this, we took measurements with the internet on and off.

We are also using a small transmitter to bounce radio signals off the ice-water interface below us, returning about 6.5 microseconds (millionths of a second) after we send out the pulse. The return pulse is not large, and the measurement proved slightly tricky - we had some equipment issues, and went through several experimental setups before getting one that worked well. The bottom photo shows the setup in our antenna laboratory building

We are also comparing the antenna properties in air and in ice. Many of these measurements are mutually exclusive, in that they require some of the same pieces of equipment, or in that they will interfere with each other. So, we need to be a little careful about scheduling and setting priorities.

Another Visitor

2009-12-18T15:27:00.001-08:00

As you can see, we had another visitor on Friday evening - a skua. He flew around the camp for a while, then made him(? - we didn't check)self comfortable. He stayed for an hour or so, mostly sitting on the ground watching, but with some periods of flying around

We rejoin the world

2009-12-16T23:53:00.000-08:00

On Wednesday morning, the wind kicks up a bit – we measure a bit over 10 miles/hour with a hand held anemometer. The Forgen wind generator turns around a few times. So, it’s time for …. kite flying

For better or worse, the wind died down pretty quickly, and the Forgen stopped turning. It is still somewhat cloudy, and we see an ice halo around the sun.

The weather on Mt. Discovery is better, and the IT crew land successfully. By prior agreement, we attempt to make VHF radio contact, without success. This is not encouraging news, since the 2.4 GHz internet link requires a better line-of-sight than the VHF radios. In desperation, we call MacOps in McMurdo, and ask them to act as a relay. We learn that the tower is up, but that work is required in McMurdo to make the link operational. Later, we get a text message (via Iridium phone) that the link is up, but have no success at connecting. When we call them, they suggest that we align the antenna to point at Mt. Discovery. We adjust the antenna, with no success. Then, they suggest setting the RF power on the link to zero, and then gradually raising it. This does not sound encouraging, but they talk Thorsten through the procedure and, to our surprise, it works – Internet! The photo below shows Martha and Thorsten working.

We have visitors

2009-12-16T17:20:00.001-08:00

Tuesday is internet day. The IT folk are supposed to arrive around noon, to put up our tower. They plan to fly out in the Bell 212, dropping off two people and a repeater tower on Mt. Discovery; the other two will continue on to visit us, and set up the tower here. The noon-ish arrival breaks up the day, since we need to put everything away before the helicopter arrives - both they and we don’t want anything blowing around.

Radio contact is made, and the helicopter comes into sight and lands. However, four people pile out, more than doubling the population of our burb. Unfortunately, Mt. Discovery was foggy, so the pilot couldn’t land. They bring a fair bit of gear, including a package for us containing a few essentials: a strap wrench, 200 feet of rope, vanilla pudding, some carrots and limes, and a cookbook. Everything that we asked for (plus the carrots and limes, which are a still a mystery).

It takes a little while to get used to the crowds. Lunch raises an etiquette question. How will we feed everyone, with only four forks, four spoons, and four knives. Plus a spork or two. Fortunately, they brought their own lunches – the easiest kind of guests.

With four people, the internet tower rises quickly, and there is lots of time to talk, compare antennae (unlike us, they usually install their antennae above ground), discuss frequencies, etc.

Because of the helicopter-winds, we do not return to the transmit-receive measurements. Instead, we dig two more antenna holes, assemble antennae, and make measurements of radio noise. The holes are starting to get a bit easier to dig, and ending up a bit deeper.

Before dinner, there was finally time to celebrate Channukah – I lit the shamash, recited the blessing, and then lit 5 candles, for the 5th night. Although the wind was pretty low, it wasn't so easy to keep the candles lit. Dinner was salmon with pesto and garlic, wild rice, and broccoli. After dinner, we finish a few anchors, and plan for tomorrow.

Maudy Monday

2009-12-16T17:08:00.000-08:00

Monday is antenna day. After breakfast, Thorsten dug a test hole for our first antenna, so about 50 feet from the station. This was partly to see how the digging goes; it will also be a site to transmit signals to the other antennae. He ended up with a roughly foot wide slot, about 6 feet deep, and 7 feet wide at the top. He needed to cut steps into one end to get to the bottom. It does the job; as you can see above, the top of the antenna is a few inches below the snow surface. We had initially wanted to dig the antennae in deeper, but this is close to the limit of our digging technology. Going deeper would require larger holes in all 3 dimensions, and far more effort.

I spent some time figuring out exactly where to put the station antennae and stomping down the ground to firm up the snow. This is more complex than we realized - between the equipment boxes that must be buried (later), the guy ropes for the station (we certainly don’t want to compromise these), within the length of the antenna cables, the choices are limited. Eventually, we decided that the East-West antenna pair must be offset – not ideal, but the best that we can do.

After lunch, I took a turn digging an antenna hole – the first for the station antennae. I do finish it, but it’s the bulk of my afternoon.

We also take measurements of antennae properties, with an antenna a few feet in the air, sitting on the snow surface, and in the hole. The simplest parameter to measure is something called the standing wave ratio; a measurement of it’s impedance (complex resistance) at different frequencies. The goal is to understand how the antenna behavior changes in ice, compared to air. We do this with a nifty gadget, an Agilent FieldFox network analyzer. Twenty years ago, a measurement like this required a decent laboratory; now we can lift the analyzer with one hand. Judging from the brochure pictures, the FieldFox is designed for use servicing cell phone towers, but it works well for us also. It is a real kick resting it on a wood plank laid on the snow to make measurements. Between that and our oscilloscope (also made by Agilent), power supply, etc, we have a reasonably well equipped lab.

Toward evening, Thorsten started working on the transmit-receive measurements, whereby we send a signal from one antenna to a second one; we expect to observe an initial ‘direct’ pulse, followed by a 2nd pulse when the signal reflects off the ice-water interface. Of course, the 2nd pulse should be much later, and also much smaller. The photo below shows our receiver laboratory, with low-noise RF preamp and oscilloscope.

Finally, this is Martha sitting at our dining room table. As in most new high-end housing, our kitchen opens to a breakfast nook, which in our case also serves as our formal dining room. If you look closely at the floor, you'll see why it's not always a good idea to choose the low bidder to install hardwood floors.

Let the Science Begin

2009-12-16T00:31:00.000-08:00

Sunday dawned warm and sunny; the clouds disappeared during the night, and the mountain tents got hot – probably in the 70’s, enough that I opened the door while dressing. Visibility is excellent; we can clearly see Minna Bluff to the South (above), and the Antarctic Coastline to the East (below), stretching away to the South (if these directions seem strange, remember that we’re about 15 miles out to sea, sitting on the ice shelf), and, with the direct sunlight, there is way more contrast than yesterday.

Breakfast was Muesli with milk, plus hot tea. We did a last few housekeeping functions – unpacking the solar chargers for the VHF radio(like you see used in war movies) and the Iridium (satellite) phone. Then, it was time to get started on science – unpacking and assembling the station ‘tower’, a 6 ‘ high metal-pipe assembly that will hold 4 solar panels, a wind turbine, and 3 GPS and 1 Iridium antennae. It should be robust enough to do this throughout the Antarctic winter.

The four tower legs sit on foot-square pieces of plywood, anchored via good sized wood screws. These go in easier with a power drill, so we needed to charge its batteries. Which meant setting up a generator. Which required opening one of the 5-gallon Jerry cans of “Mogas.” Unfortunately, someone did an extremely good job of tightening their caps; they defeated the best efforts of our hands, plus two improvised strap wrenches, one using Martha’s belt. Finally, we were able to open one can; this should be enough to hold us until Monday.

Lunch was gardenburgers with provolone cheese (the Swiss cheese preferred by some residents is still frozen) on bagels, plus curried lentil soup (from a package). The soup was OK (Martha and Thorsten would call it good), but the gardenburgers are great.

We used the Iridium phone for our 1 pm daily check-in with MacOpps. It is quick and easy, but the VHF radio might be cooler – we need to find time to set it up.

After lunch, the station tower came together, with its complement of equipment. It seems ricketier than it did back in Berkeley, but most of the strength should come from the guy ropes.

A word about snow, since we heard a variety of predictions. The snow here is quite fluffy, with a bit of a crust. Usually, boot sink in 4-6 inches. However, sometimes the crust holds, and you don’t sink in. This does not make walking easy. So, generally, putting the "deadman" anchors in was fairly easy. However, we have compacted the snow around the tower (by trampling on it), and so the digging is a bit harder. We also want these to be deeper –18 inches to 2 feet. So, they take some time.

Also after lunch, I called Ruth (my wife). The first try was one-way only; the 2nd worked well. For a guy who doesn’t even own a cell phone, it was strange standing on the ice in the middle of nowhere, talking to someone 2 continents away. They are celebrating Channukah. I brought a menorah and candles, and will celebrate once we’re a bit better established. Being away from my family is definitely the worst thing about this trip.

In the afternoon, we continued with the station setup. By dinner (rice and bean burritos, with cheese, green chili and salsa), most of the station was set up, but not yet connected:

We also worked on assembling the five dipole antennae. These are essentially TV antennae, with "some assembly required." Assembly is a bit painful. They have many screws, and not every box has everything that we need. There is considerable play in some of the joints, so there will be some antenna-to-antenna variation.

It's a good start.

We make it to Moore's Bay

2009-12-16T00:09:00.000-08:00

Saturday, 9 am. The weather doesn’t look too promising, with a good layer of high clouds, but the pilot is game to try again, so we reboard our Bell 212, facing the now-familiar luggage wall. The 50 minute flight is relatively uneventful, and the site is free of fog or low clouds. But, with the high clouds, the light is very diffuse, and, from 3000 feet up, there is no surface definition – there are no visible features on the ground, so the pilot can’t tell how high we are; this makes landing difficult. We fly around a bit, chasing a patch of sunlight that is an indeterminate distance from the desired landing zone. After 5 miles, it doesn’t look much closer, and we don’t want to go too much farther, so we turn around, and descend to 2500 feet. Now, the pilot and helo tech in front can begin to make out ground features, so we continue down, past 300 feet when the ground approach warning blares. In the back, we passengers can see features in the ice, but can’t tell how high we are. I was quite surprised when the pilot said that we had landed – it was a very soft touchdown, and, from the side windows, we still appeared airborne.

Once down, Brian hopped out with his avalanche pole, and quickly checked the area for crevasses. He found none, and we unloaded our gear – most of our priority one stuff. Martha checked in with MacOpps on the satellite phone – contact is required before the helicopter can leave.

The remainder of our gear – including our two large tents - was scheduled for a 3:30 supply flight, along with our science cargo. We would certainly survive without this gear, but wouldn’t be particularly comfortable. And, we would have relatively little to do.

We began setting up the tents we had – two “Mountain Tents” for Martha and I, plus a ‘Kiva” for our toilet tent. Until the 2nd load arrives, the Kiva will serve as our cooking tent. Brian sets out to check a 1 km line; we walk out along this line, and test transmission/reception over significant surface distances – 300 m and 1 km. Brian pushed a snow anchor into the snow, connected a 50 m climbing rope to it, and walked off, connected by a prussic (a knot around the rope that will hold if he falls), probing the snow every 20-30 feet with a ~ 4 m long aluminum avalanche pole. He is searching for voids that would signal a large crevasse. I follow; my job is to pull out the snow anchor when he reaches the end of the rope, and bring it to him.

He commented that, with the snow this flat, it did not appear that the site was subject to high winds. The “no high winds” contrasted with what we heard from other people, but his logic makes sense. It also meshes nicely with the almost still conditions since we got here – if this persists, the wind generator will not be useful.

By the time we get back, the tents were set up, and Martha and Thorsten have the stove going, and ‘lunch’ is ready – hot water, to which one can add a variety of dried soups, tea, etc. There is no ‘inside’ place, and it feels very ‘outdoorsy.’ After lunch, we’re out of things to do so we sit on our sleep kits and talk.

Around 2:30, we call in on the satellite phone, and learn that the helos are running about 40 minutes late. Brian would really like to get back tonight. Around 4:10, we try to reach the helo on VHF radio, with no result. We call again, and hear that 36J is about 15 minutes out, and we ‘should’ be able to see it. About 10 minutes later, we hear 36J reporting in to McMurdo that he’s 12 minutes out, and make radio contact. A little while later, he reports that he thinks he can see us; the reverse is not yet true. Thorsten is the first to spot him, 3 dots in the sky.

A few minutes later, it’s almost overhead. As he flies overhead, he kicks up a big wind; surprisingly, the wind area is only a few times larger than the radius of the rotor blades. Thorsten and Martha are (as requested), sitting on the supplies to ensure that nothing light gets blown away. He lowers the two sling loads about 10 feet apart, then moves about 50 feet away to land and pick up Brian. We unload 6 4 foot by 4 foot plywood squares – our helicopter-friendly tent floor. Of course, between the loose snow and rotor wash, dragging the plywood is not a ball of fun.
The photo below shows the helo and sling load, and the plywood unloading operation.

A few minutes later, we waved goodbye, and they flew off. It is 5 pm, and we have two tents to set up before dinner and bed. Fortunately, it doesn’t get dark here. The big tent is an “Artic Oven, 10 feet by 20 feet, with a 5 poles on each side, connecting at the top in 3 ‘spiders.’ It goes up easily enough, but then there are the guy ropes to attach. For each rope (or group), we need to dig a 2 foot deep hole, bury a 1 ½ to 3 foot long bamboo stake, wrap a rope around it, tighten it, tie the rope taut,, and then refill the hole with snow. These are called “Deadman” anchors - a fair bit of work. Thorsten’s ‘Scott Tent” also requires setup. While Thorsten and I do this, Martha makes dinner – tricolor tortellini and green beans. Yummy. By this point ( 8 pm), I’m zonked out and go to bed; I believe that the others follow my example pretty quickly.

The top photo shows most of our camp - the largest and finest in Moore's Bay.

All in all, a pretty successful day.

The end of the hiatus

2009-12-16T00:06:00.000-08:00

Hi,

It is now Wednesday (Dec. 16) here (one day later than in the States), and the internet is hooked up and working. Camp is set up, station installation and measurements are underway, and we're all happy and healthy. And even warm.
I have been writing blog entries, and will now post them, but it will take a few days to catch up.

Spencer

Mt. Discovery

2009-12-11T00:02:00.000-08:00

The one good thing about the Moore's Bay 'boomerang' was that it let me come along on the recce expedition to look for a site for the internet repeater. We got back to the heliport around 1:30, just in time to be on time for the 2:10 flight to Mt. Discovery. Lunch was two small packages of pretzels - nothing but the best for us.

This time, we went in an AS350 "Astar" Eurocopter. This is a smaller, single engine copter that seats 5(?), including the pilot, in a single cabin. This time, I got to sit up front; there are windows all around, and it definitely felt 'airy.' There was even a window right by my foot:

The switch by my toe controlled the intercom.

We flew for about 30 minutes, following our earlier route (we had passed Mt. Discovery going to/from Moore's Bay.

The top picture shows 8796 foot high Mt. Discovery, taken partway up the side. The photo below, taken looking in the other direction, shows Minna Bluff:

McMurdo station is off the the left, while Moore's Bay is to the right. We were looking for a site with good line-of-sight in both directions. We quickly spotted several possible sites. The first possible site was on top of this rocky point:

To me, it didn't look big enough to land a helicopter on. Pablo (our pilot) made a pass, then decided that, although he could land there now, this feat would not be repeatable if the wind were higher. So, we moved higher up the mountain, and found a larger flat area for a helicopter, with several reasonable points to put a repeater on:

Bill and I got out, and, although intervening clouds prevented us seeing McMurdo, he was able to contact them with a line-of-site VHF repeater. At the same time, we had a view of Moore's Bay. It was quite a bit colder than in McMurdo, and it was surprised how quickly I got out of breath walking around. Still, I was astonished when Bill told me that we were at an altitude of over 5,000 feet. I really hadn't felt us climbing. And, going back, we didn't seem to lose altitude.

A good site found, there was no need for plan B, an alternate possibility on Minna Bluff. The photo below, from our return flight, shows Hut Point, with McMurdo station in the middle, between the two peaks:

And finally, a view of McMurdo, as we came in to land:

We're scheduled to try again for Moore's Bay tomorrow at 9:00 am, so I'll sign off now.

To Moore's Bay .... and back

2009-12-10T20:14:00.001-08:00

We arose Friday to reasonably promising weather, and an 11:40 departure. The photo above shows us heading to the helicopter. The helicopter was a Bell 212, with the pilot and helo tech sitting in front, and the four passengers squeezed in back, along with our priority 1 luggage (e.g. food, extra ECW gear, etc.), where additional passengers would otherwise go. We took off, heading South, across the Ross Ice Shelf. Even though the windows were not designed with sightseeing in mind, the view was spectacular:

It was amazing to see so many different forms of snow and ice, complementing the black, stony mountains:

It was also interesting to see places where the snow/ice had clearly melted and refroze (the blue areas in the panoramic photo above). We also flew over Pegasis airfield.

Unfortunately, after we cleared Minna Bluff, we saw that Moore's Bay was covered in low clouds. We couldn't land, so had to turn around and head back to McMurdo.

Unfortunately, these photos don't do justice to the views (although you can click on them to blow them up).

The plan is to try again tomorrow, weather permitting. I'm not so optimistic; a low pressure front has been anchored around here for a while, creating the slightly unusual weather.

Interlude

2009-12-09T20:55:00.000-08:00

We will not have internet access for the first few days in camp; if we go tomorrow (i.e. the weather cooperates), it will be a few days before my next post. It is also possible that we will never get internet, in which case it will be longer.

Why are we doing this?

2009-12-09T19:57:00.000-08:00

Since I have a few quiet moments now, I thought it would be a good idea to explain what we are trying to do with ARIANNA.

In the 19th century, scientists observed that the earths surface was permeated with a mysterious radiation which did things like discharge electrometers and cause certain materials (scintillators) to occasionally give off flashes of light. Noone knew where this radiation came from, but the prevailing assumption was that it came from the Earth. To test this, in 1911-1913, physicist Victor Hess made a series of balloon flights, eventually reaching 5300 m (about 17,000 feet). To his surprise, he found that the radiation increased as he ascended: the mysterious radiation came from space.

By the 1930's, scientist had learned that the radiation could cause Geiger Counters (simple electronic radiation detectors) to occasionally fire simultaneously, even if they are separated by distances of many miles; these simultaneous hits are called cosmic-ray air showers. We now know that these showers occur when an ultra-high energy cosmic-ray particle (a proton (hydrogen ion) or heavier nucleus, like iron) hits the top of the atmosphere and interacts with an oxygen or nitrogen atom. It converts it's kinetic energy into a large number of particles (remember E=mc^2); showers containing trillions of particles have been observed; This corresponds to an initial energy of about 3*10^20 electron Volts, roughly the energy of a well-hit tennis ball, or a boxers punch. The Auger collaboration has produced a nice animation of a shower being created, here. To put things in perspective, the highest energy cosmic rays have about 40 million times the energy of the protons accelerated at the LHC (and more if the cosmic rays are heavy ions), and it would require an accelerator 40 million times as large as the LHC to accelerate them. With current technology, one would need to build an accelerator around the sun to produce these particles. We would very much like to know where these cosmic accelerators are, and how they work.

However, despite decades of study, we do not know where these particles come from. They are electrically charged, so are bent in interstellar magnetic fields; even when we record their arrival direction, they do not point back to their sources. We don't even know if they are protons or heavier ions. Furthermore, the most energetic cosmic rays lose energy in transit, so the ones that we observe must come from the 'local' universe, within about 75 million parsecs (225 million light years) of Earth. This sounds like a long distance, but, on cosmic scales, it isn't very far.

Because of the bending and limited range, to learn more, we need another probe. Neutrinos are attractive, for several reasons. First, being electrically neutral, they are not deflected in-flight. Second, they interact weakly, so can easily escape from dense sources that would contain other cosmic rays.

The flip side of the weak interactions is a huge detector is needed to observe cosmic neutrinos. IceCube, shown below, now being built at the South Pole will be 1 cubic kilometer (about 0.6 miles on a side) in volume. This should be (but no guarantees) big enough for moderate energy neutrinos (from 10^8 to 10^17 electron volts). At higher energies, we do not expect many neutrinos, and need a larger detector. Probably, a volume of 100 cubic kilometers is required; this requires a new technology. Our goal for this winter/summer is to demonstrate this technology: radio detection of neutrinos.

In 1962, the Soviet-Armenian physicist Gurgan Askaryan pointed out that the particle showers produced by neutrino interactions will contain more electrons (which are negatively charged) than positrons (positively charged). These particles are all moving in a almost the same direction, producing an electrical current; in a dense medium, this current will emit radio waves in a cone. The strength of the radio waves scales as the square of the neutrino energy (the process is coherent, for physics experts), so we expect good signals for neutrinos with energies above about 10^17 electron volts.

A number of groups have worked on detecting neutrinos via the Askaryan effect. Collaborations have looked for neutrino interactions in the moon (using radio telescopes), the Greenland ice cap (looking down from a satellite), at the South Pole, and in underground "Salt Domes." Groups are also looking for acoustic radiation produced by neutrino interactions; the shower deposits energy in the target medium, producing a sound wave. These diverse methods have their plusses and minuses. The big advantage of ARIANNA (shared with the South Pole effort) is that it can detect neutrinos that are less energetic than the other approaches. Also, the ice-water interface below the 650 meter thick Ross Ice Shelf reflects radio waves. Because of this ARIANNA will be able to detect downward going neutrinos.

If our prototype works well, this will give us the basis to propose a larger detector, composed of many stations, which would be big enough to detect a good sample (maybe 100 events) of cosmic neutrinos, thereby solving at least some of the mysteries of ultra-high energy cosmic rays.

Yet still more packing

2009-12-09T19:39:00.001-08:00

Wednesday morning,we picked up our communications gear - 1 55 pound HF (High-Frequency) radio, two ~ 1 lb VHF radios, and one iridium satellite phone.

After that, most of the day was focused on repacking our scientific equipment. Of course, we figured out the one (so far) thing that was left in California, and spent some time figuring out how to work around it. Most of our stuff goes in a 1 meter^3 box, weighing 500 pounds. The station box weighed 110 pounds, and the other boxes were lighter. The main confusion was over the sealed lead-acid gel batteries (essentially car batteries, but adapted for colder temperatures). After some confusion, we learned that they are not considered hazardous.

We again ate dinner with the IceCube folk - both the northbound and southbound planes were canceled due to weather. The weather was actually bad - just a bit windy - but there was some concern that, when the wind stopped, it would get foggy. That actually happened (see photo below), but it wasn't that bad.

The one significant remaining open issue is internet access. The plan on Thursday is to send a helicopter recce on Friday to Mount Discovery, to look for a place to put a solar powered repeater station. We will bring the ~ 250 lbs of gear required for our side of the link with us.

The tent floor issue is resolved. The regular "Artic Oven" tent floor weighs 300 lbs, and is awkward for the helicopter to carry. We will bring plywood sheets instead, which should cover most of the floor.

On Friday morning, we took everything over to helicopter operations, and categorized it by priority: 1 = cooking and camping gear, and 2 = scientific gear. The heavy gear will be carried underneath the helicopter in a sling. This will be a second flight, both because of weight restrictions (not counting the passengers + worn ECW gear, we have 2900 lbs of stuff), and because safety regulations don't allow passengers on a flight carrying a sling. The current plan is to have Brian come in with us, and then have the 2nd flight about 4 hours later; he will leave on that flight, after the sling is removed. That should give him enough time to check the ground for crevasses.

On Friday afternoon, the scheduled helicopter recce flight was cancelled because of the fog. With our gear packed, we spent the afternoon taking it easy, relaxing, etc. We're not alone - the Pole flight got out, but Mike Z. is still stuck here, bemoaning the Hawaiian vacation that he is missing.

We leave tomorrow, so this will be my last 'travelog' post for a while. The current plan is to try to get the internet link running early next week (Monday or Tuesday); once that is in I will be able to resume posting.

Packing, Packing and more Packing

2009-12-07T22:55:00.000-08:00

Preparations for the trip are moving into high gear. On Saturday, after field school, we met with Jessy Jenkins, our Point of Contact (POC) for the trip. Jessy works in Berg Field Camp (BFC), which provides food and equipment for field camps. She arranged for a BFC person to accompany us, in addition to the mountaineer who will be with us the first 1-2 days. We also learned that the mountaineer will be Brian Hasebe, who taught our "Happy Camper" class.

On Monday, we met Martha Story, who will accompany us. Both Martha and Jessy were extremely helpful, and I finally feel that I have a good picture of most of what needs to happen. We also met with the helo ops supervisor, Julie Grundberg, about flight planning. We have to request our flight(s) three days in advance; to do so, we need an accurate estimate of what everything weighs; this, in turn, requires that we know what we are bringing, bringing renewed emphasis to packing. We will need two flights to get in and out: one for us and some personal gear (sleep kits, etc.), and another for hazardous cargo (mostly fuel) and scientific gear; the big pieces will go in a sling under the helicopter.

On-site internet access remains an open question. The current site does not have the required line-of-site to any of the existing internet repeaters. The options are to move the camp, or to install an additional repeater. It is not clear how large a camp move would be required, and the IT folks here are suggesting putting in a repeater on the side of Mt. Discovery. There will be a helicopter recce to look at this possibility, probably on Thursday.

Martha will cook dinners in camp, and, with her help, we quickly mapped out menus, and ingredients from the 15 page list of BFC stock. She will also bake bread out there (her idea). There was a rather wide variety, with a reasonable selection of frozen meats, vegetables, breads, etc. plus a fair selection of canned goods, and pre-prepared dishes. There is also a wide selection of dried soups, freeze-dried meals and snack foods, for quick eating. Menus planned, we then went to "Food Pull," and picked up everything on our list. This photo shows us with our selections (except the frozen foods, which were picked up outside). We ended up with

This killed most of the afternoon. Thorsten found some time to work on the box, and I spent some time fighting ROOT (a physics analysis software package) and Windows XP - they do not play nicely together, in order to be able to analyze the data on my laptop.

Tuesday brought more briefings, and more packing. First up was training to use our generators and chainsaw. The generators seem pretty straightforward; the chainsaw less so. The hardware isn't complicated, but it seems like something where one would want some actual experience. Fortunately, Thorsten used a chainsaw during his time as an IceCube driller.

Next was a briefing on communications protocols. We need to report in at a specified time every day. Otherwise, they will send out the search and rescue team. We will have VHF and HF radios (just like in "Happy Camper"). The VHF radios are line-of-sight, so are only useful for talking among ourselves, or maybe with a passing aircraft. We will also have an Irridium satellite phone. We will get these at another briefing, on Wednesday.

The rest of the day was devoted to packing our gear, which took far longer than I expected. This photos shows most of our camping gear; our sleeping kits (sleeping bag, foam pads, etc.) are elsewhere, and the largest tent is also elsewhere. Fuel (propane for cooking and heating, "Mogas" for the generator, and "premix" (a gas/oil mixture) for the chainsaw were already filed as hazardous cargo.

The camping gear weighs about 831 lbs. 300 lbs of that is a floor for our "Artic Oven" tent, not shown here. Without the floor, the heat of everyday activities (cooking, using the oscilloscope and network analyzer, etc.) will gradually melt a hole in the snow, and we will have to move the tent.

We had dinner tonight with a number of IceCube folk. Mike Zernick is on his way home from the Pole, and Jim Yeck and Andrew Laundrie are on their way there. The IceCube construction season is off to a great start; they have already finished their first hole.

Science and Seals

2009-12-06T00:43:00.001-08:00

It may be hard to believe, but there is science beyond neutrino astronomy. Sunday is the day off for most people here, and this Sunday was a good opportunity to explore some of the other things that are going on here.

One opportunity is the weekly tour of Crary Lab, where we heard about a diverse range of topics. We started out at their collection of biological and geological specimens. One feature was a fossilized tree stump from the Permian era (220 to 270 million years ago). It is a clear reminder that Antarctica wasn't always so cold.

We also heard from several scientists. One gentleman told us about his work measuring environmental contamination in and around McMurdo; the main issue is from fuel spills. We also heard a bit about monitoring of the Mt. Erebus volcano - it spits out lava bombs quite frequently. I briefly explained what we are doing on ARIANNA. But, the highlight of the tour was a visit to the 'aquarium' where biologists study local flora and fauna. It was pretty quiet when we were there, but there were some interesting specimens (all invertebrates):

The black shell is a scallop, and the white flowery creature is an anemone. I think that the 7-legged thing is a starfish of some sort (there were several similar ones with 7 legs, so it's not an anomaly).

After this, I went to the SCINI (Submersible Capable of Under Ice Navigation and Imaging) open house. They have developed a torpedo-shaped robot that can swim around under water, controlled from the surface. They were set up in a small hut sitting on the ice; they drill a hole through the ice and lower the torpedo down it.

We got a chance to actually 'drive' the torpedo around. It was pretty cool, and surprisingly easy - four buttons for direction, plus another toggle for up/down. The ocean floor was surprisingly prolific - lots of sponges of various types. We also saw one or two fish swim past. The tether is about 1 km long, and provides power and control. To go further, they load everything up on a piston bully:

and drive to another spot.

But, the highlight of the day was outside the SCINI hut: four black Weddell Seals. Three were adults, 8-10 feet long, and weighing up to 1,000 pounds; the top photo is an example. The last was much smaller and lighter colored, a pup maybe 3-4 feet long. They apparently came up through a hole in the ice, and were enjoying the sun.

After this, the Sunday science lecture, where Drs. Peter Doran and Bill Stone discussed the Endurance project. The group has built an autonomous (untethered) underwater robot. They are exploring Lake Bonney, an ice covered lake in a nearby dry valley. Te long-term view is toward developing a vehicle that could explore the seas of Europa (one of the moons of Jupiter).

Survivor Antarctica!

2009-12-05T15:44:00.000-08:00

Snow School (aka "Snow Craft One" or "Happy Camper") started easily enough, with about two hours of classroom lectures on hypothermia and frostbite, with only a few graphic pictures. Then, we (10 students + Brian, our instructor) climbed onto the Delta (shown below, coming to pick us up), grabbed lunch from the kitchen, and headed off to the middle of nowhere (actually, only a few miles from town).

After learning how the stoves worked, checking our food and gear, and eating lunch in a hut, we gathered our gear, moved to an open area, and started making camp. This entailed setting up tents, building a snow wall upwind to protect them:

The "kitchen" was a pit to stand in, a flat area for the stoves, and another snow wall upwind, to keep out the wind:

That's Brian in the kitchen. Brian also showed us how to dig an emergency snow cave:

One of the 'students' decided to finish this, and sleep in it.

Building snow walls was interesting. You start with an undisturbed patch of snow, and dig a trench along it. Then, you use a snow saw (a regular wood saw would work fine too) to cut the snow into blocks about 1 foot by 2 feet. Then, you can put a shovel underneath the blocks, and pop them out of the ground. With a little care, they come out intact, and can be easily built into walls, etc. They are easy to saw into special shapes, so one can easily fill in the irregular areas.

Setting up camp took most of the afternoon. Afterwards, Brian handed us a radio, bade us good night, and headed back to the I-Hut. This photo shows our camp, from the upwind side.

We were lucky with the weather. It was fairly warm, right around freezing, and mostly not too windy. However, as we were setting up camp, it began to get windy, and, by the time we cooked dinner, it was gusting up to 30 miles/hour. This made eating rather difficult, since we had to remove ones gloves to be able to use the plastic spoon to eat out of the freeze-dried food package. One of my roommates in McMurdo said that it was 40 below when he took the class. That must have been rough.

It was also cloudy; this made the snow rather featureless, and it was pretty hard to see the contours of the snow; you couldn't, for example, easily see the edge of a depression, and you had to be careful walking. The lack of contrast also shows in the photos; it is hard to see our snow walls, for example.

Aside from the slightly cramped tents, sleeping was pretty comfortable. We learned the importance of smoothing out the area underneath before setting up our tents. Our sleeping bags were overkill for the temperature, and we left the tent door open, partly because we were warm and our feet were hanging out.

Breakfast was pretty limited, due to a packing oversight. Then, we took down the tents, packed up camp, and headed for the I-hut. This was "Car Camping;" Brian transported most of the gear in a sled behind a snowmobile.

In the I-Hut, we learned about the HF (5-10 MHz) and VHF radios. The VHF radios are line-of-sight, while the HF radios (designed for military use), with appropriate antennae have a transcontinental range, as the signals bounce between the ionosphere and the ground. The HF radio has two roughly 50 foot long wires that are spread out to form a center-fed half-wave dipole antenna; there are alligator clips on each wire that can be removed, to shorten the antenna, to tune it to different frequencies. Since only 6 frequencies are used here, it works pretty well.

Then, it was time for the infamous "head in a bucket" exercise. The buckets simulate white-out conditions - zero visibility and lots of wind noise. Brian, our instructor, went to the bathroom, and never came back. We need decide what to do. We have a rope which can be tied to the building; as long as we hold on to it, we won't get lost. However, how do you coordinate a blind search party? We send two people out to try to find the bathroom; I'm one of them. We will try to follow the line of stakes leading to the bathroom (placed ~ 15 feet apart, to avoid just this scenario) to see if he has taken refuge in there. We find the 4th stake (missing the first three), then get the rope tangled in it, until Brian stops the exercise. For our second try, we send out the entire group, spaced ~ 6 feet apart (we tie loops in the rope to facilitate spacing and holding on). We will try to spread out in line and do a circular sweep. This goes surprisingly well, until we reach the line of flags to the bathroom. Some people want to keep going, while others want to stop, as we had discussed. We end up with a v-shaped 'line.' at which point Brian ended the exercise. He did say, generously, that we might have eventually found him, if he was in the area that we were searching. The clear lesson is not to get lost.

We moved on to the survival bags that are carried on all flights, etc. They contain supplies for two people for 3 days - sleeping bag, tents, stove, food, etc.).

Then, back outside for our 'final exercise. Our plane has crashed and the pilot broke his leg. What do we do? We quickly split up into groups, erecting the tent, keeping our injured pilot warm, building a snow wall, starting a fire to melt snow, etc. I set up the VHF radio. Instead, of calling in an emergency, Brian asks me to radio the South Pole (850 miles away) to ask what the weather is there. The South Pole Ops center is obviously used to these calls; it's a balmy 14 below (probably Fahrenheit).

After that, we clean up, wash dishes (fortunately inside) and board the Delta for the ride back to town. There, we put away everything, refill the food boxes for the next party, and watch a helicopter safety video and try out helicopter seat belts before being dismissed.

Briefings, Briefings and More Briefings

2009-12-04T23:27:00.000-08:00

Thursday, our first full day in McMurdo is devoted mostly to briefings. After a cafeteria breakfast, we started in Cracy lab (the main science building) at 8 am, with "Crary Lab Safety", followed at 8:15 by "Environmental Field Brief." We aren't going to the dry valleys, and had already taken the online course on "Protecting Antarctica's Environment." so get out a bit early.

At 9:30, the "Science" (really logistics) briefings began in the "Chalet," the house-sized NSF office building. About 9 people took turns telling us what they did, and why we need to talk to them later. Fortunately, our briefing books list these meetings in more detail:

meet with our "On Ice POC (Point of Contact)
meet with the Crary Lab materials supervisor,
get our laptops set up to use the wireless,
go to a communications briefing
check out radios
meet with the Crary lab management about space
Check out the equipment that is being provided to us
Prepare for "Food Pull" where we will select the food we want to bring
Get trained on our generators and chainsaw
Pick up our generators and chainsaw
Meet with the Helicopter Operations Supervisor about planning our flight and packing our cargo.
Get briefed on waste management

These meetings follow a similar pattern. We are asked "What do you need?" Often, we don't know enough to intelligently answer that question. Fortunately, almost everybody that we talk to does have very good answers, all we have to do is agree with their usually excellent choices.

These meetings also highlight the vital role that planning and logistics play in Antarctic science. In the field, there is no corner store to buy a soldering iron or generator (or even a bottle of juice).

In between the meetings, we look at our gear, unpack the electronics box, and begin testing things. Everything seems to work; the only hiccup is that some network settings for the Iridium satellite modem need changing in the new environment. Also, one antenna needs some glue to repair some transit damage.

The picture shows Bldg. 155, where Thorsten and I are staying. It also houses the cafeteria, store, automatic teller machines (the only ones in Antarctica) and houses some adminstrative functions. Note the finely landscaped boulevard.

Tomorrow: snow school.

Mac Town

2009-12-02T23:41:00.000-08:00

After arrival, we were taken directly to a series of briefing, covering health and safety, environmental issues, housing, and our return flights. Thorsten and I are in Bldg. 155, which also houses the cafeteria, store, a crafts room, etc. We are both in rather crowded 5-person rooms; there is not a lot of room for storage (or anything else) in the rooms. One nice thing about this place is that everyone is friendly, and most have very interesting life stories.

The weather here is quite balmy – sunny and only a few degrees below freezing. Unfortunately, it was also pretty windy the first day. On-base, the ground has a pretty thin layer of snow/ice on it. During the day (the sun never goes down, but it is higher in the sky during the day), much of this melts, and there are pools of water, and small streamlets running down the roads. You have to be careful where to step.

Mac Town is a medium sized settlement, with a current population of about 1,100, dropping to around 200 in the winter. The architecture is low-budget mining town; unattractive buildings with dirt/gravel/snow streets. Although there is a push to reduce energy consumption, many of the buildings are quite old, and not exactly energy efficient.

Meals are cafeteria style. At dinner, the main dishes were brisket, thai style catfish, or a chili, plus soup, vegetables, potatoes, deserts, ice cream, etc. Plus a wide selection of drinks. After dinner, Laura, Thorsten and I walked down Discovery Hut (commonly known as Scott’s hut), where the Scott party wintered over in 1902. The top photo shows Discovery hut in the foreground, with the modern McMurdo base in the background – the ultimate in suburban sprawl. The bottom photo, taken from near the hut, shows the Sea Ice “Airport,” with 3 LC130’s. The LC130s can take off and land on both wheels and on skis; the skis are used in softer snow.

Across the Antarctic Ocean

2009-12-02T17:30:00.000-08:00

The adventure begins! Check-in at the Antarctic terminal was at 6 am for our 8:30 flight. We changed into ECW (extreme cold weather) gear for the flight, had our temperatures taken (no sick people are allowed in Antarctica) checked our checked luggage and boomerang bag, and checked in for our flight. In addition to our checked baggage, they also weighed the passengers and carry on luggage (“please step up onto the scale.”).

ECW gear is required wearing in case of emergency. My 2006 flight back from the Pole clearly showed why this is a good idea – the cabin heating on our LC-130 failed, and the cabin temperature dropped below freezing. Way below freezing. But, we stayed comfortable.

The ‘boomerang’ bag contains clothing for a day or two, in case we ‘boomerang.’ A ‘boomerang’ is when the flight South is unable to land at McMurdo, so returns to Christchurch; checked luggage stays checked, but the boomerang bag is returned.

Then, we had an hour to kill - time for a light breakfast. Then we watched a safety video (everything from appropriate clothing and frostbite and sunburn to construction safety in 15 minutes), went through security screening, and boarded two buses to drive through the rain to the plane.

The C-17 is a large 4-engine jet transport, built to land on unimproved runways. Ours was operated by the U. S. Air Force transport. There were only 53 passengers on this flight, so the center of the plane was filled with cargo. Most people sat in jump-seats on the side; there were a few airline style seats in the front center. Here are a couple of pictures I took of the passenger/cargo area

and cockpit of the C-17:

There was limited sound insulation, so they passed out earplugs. “Inflight Service” consisted of 3 jugs of water and some cups, plus earplugs (there was limited sound insulation). Bag lunches and water bottles were distributed before boarding.

As we neared the Antarctic coast, the clouds thinned, and we got some views of ice-covered ocean. The ice extended at least 300 miles from land (and this wasn’t even the ice shelf). The photo (below) shows Sturge Island in the background. It is part of the Balleny Island Group. The photo was taken through one of the two less-than-pristine windows on each side of the plane.

Later, we saw the Antarctic 'coast', before we had to sit down and fasten our seat belts for landing.

We landed on the Sea Ice Runway, just offshore from McMurdo station. This runway will close soon, when the ice gets too soft, and C-17 operations will shift from Pegasys field, a “white ice” runway, a 45 minute drive to McMurdo. Here we are deplaning:

Today in Christchurch

2009-11-30T20:38:00.001-08:00

Christchurch is a beautiful city, with a lot of beautiful old stone buildings. This picture shows the main cathedral, next to a "The Chalice," (possibly better known as "The Ice Cream Cone").

At breakfast, I ran into Laura Gladstone, a UW (Madison) graduate student on IceCube; she is on her way to the South Pole to test digital optical modules (DOMs). Laura, Thorsten and I then went to the University of Canterbury, where we lunched with the local IceCube group. This is Suruj Seunarine last week there - after 9(?) years he is moving to a faculty position at the University of the West Indies, on Barbados.

After lunch, the main event was our appointment at the Clothing Distribution Center (CDC), where we received everything from long underwear and wool socks to warm parkas and snow goggles. And again, more pairs of gloves and mittens than I knew what to do with - leather mittens, 2 pairs of leather gloves (I gave one back), snow gloves, glove liners.... Since we had to try everything on, this took some time.

Later, Thorsten and I wandered around the Christchurch botanical garden, which is really amazing. Especially the heritage rose garden (below):

There is also a nice display of water plants (below):

We need to be back at the Antarctic center at 6 am tomorrow, for a planned 8:30 (?) departure.

Halfway (?) There

2009-11-30T00:16:00.000-08:00

After a long flight and a few adventures, we made it to Christchurch, NZ.

The fun started at SFO. I had no problems, but Qantas (Australian airline) had real problems with Thorsten's boarding passes. At the check-in counter and gate, we heard a string of improbable excuses: You need to get electronic visas for Australia (at a cost of $25) [even though we never went through Australian immigration], New Zealand Immigration thinks that your passport has expired, and, finally, there isn't enough time for him in Sydney between flights [then why did you sell us this ticket? Maybe they think I can run faster than him]. In the end, they gave him a SFO to Sydney boarding pass and told him to try again in Sydney. They also checked all 3 of our bags on my ticket [the alert reader will note a bit of literary foreshadowing here].

The flight to Sydney was as nice as a 14 hour flight can be. The plane was about 1/3 full so we had room to stretch out, there were only a few crying babies, and the food and entertainment system were a cut above most U.S. airlines [n. b. this was a code-share flight and we had "American Airlines" tickets, so satisfied the "Fly America" act]. Due to winds, we took a very westerly route, flying by Hawaii, and then south over the Solomon Islands. Unfortunately, the sun was just coming up,and we couldn't actually see any islands.

In Sydney, we had 40 minutes between flights - plenty if we both had boarding passes. The Qantas "Transit" Desk first ascribed this to NZ immigration, and then said "This happens now and again," and, after a few tries with unanswered phones, was able to reach a supervisor who could override the hold, and print a boarding pass. Thorsten was the last one on board.

After another 3 hours flying, we arrived in Christchurch, went through immigration, and waited for our bags. And waited. And waited. It seems that our bags like Sydney so much that they decided to take a later flight. Unfortunately, our oscilloscope, which requires special customs clearance, was in one of the three bags, checked in my name, even though the customs form listed Thorsten's name. And, we didn't even know which luggage tag it was. As a further complication, we used the same customs form for our carry-on network analyzer (no traveler should be without one). After some confusion, this was at least theoretically sorted out, and the oscilloscope will clear customs and our bags should be delivered to our hotel tomorrow morning.

Fortunately, the FedExed ARIANNA electronics box did arrive and cleared customs, and it scheduled to be on our flight South.

Christchurch hasn't change much in the past year and a half. It is still a very visitor-friendly (and generally friendly) place. Unfortunately, today is cold and slightly rainy (even though it is summer here). And my umbrella is still in Sydney.

Getting There is half the fun

2009-11-27T20:23:00.000-08:00

An influential reader (full disclosure: my wife) thought that it would be helpful if I posted a map of Antarctica, showing where we're going. We will be on the Ross Ice Shelf, near the bottom of this map. Initially, we will be based at McMurdo station, shown by the red dot. This is the main U. S. base in Antarctica, a major logistical hub. There, we will go through "Snow School" and other training, gather our food, tents, generators, other equipment, etc. Then, we will be helicoptered to Moore's Bay, about 70 miles away. Very roughly, it is below and to the right of the "F" in "Shelf".

We will travel there via New Zealand. We will fly from San Francisco to Christchurch, NZ, via Sydney, Australia (not the most direct route, but at least it's only one stop), crossing the international date line and arriving Monday morning. On Tuesday, we will go to the Clothing
Distribution Center (CDC), where we will be issued a full range of cold-weather clothing. On Wednesday, weather permitting, we will fly down to McMurdo, most likely on an air force C-17.

This photo, from 2006, shows the C-17 that I flew on to McMurdo, for a trip to work on IceCube. Then, we flew C-17s to McMurdo, spend the night there, and then continued to the South Pole on an LC-130, which landed on skis. The bottom photo shows an LC130 landing at the Pole, also from 2006.

The Tip of the Iceberg

2009-11-25T14:58:00.000-08:00

I’d like to give you some idea of the huge amount of effort that it takes to make a scientific endeavor like this a success. Our time in Antarctica is just the tip of the iceberg; a large number of scientists and engineers have contributed to ARIANNA. Equally importantly, many, many people have been working behind the scenes to provide the logistical support. Without enough food, fuel, clothing, equipment, power and transportation, this would be an uncomfortable and unproductive trip.

Although we will only be in Antarctica for a few weeks, preparations began many months ago. Special mention goes to Steve Barwick (UC Irvine), who is the ‘father’ of ARIANNA. He and Dave Saltzberg (UCLA) visited Moore’s Bay in 2007 and made initial measurements of the how radio waves propagated through the ice and reflected from the ice-water interface. Steve described ARIANNA in preprint arXiv:astro-ph/0610631.

Steve arranged this trip with the National Science Foundation (they run the U.S. bases in Antarctica) and with Raytheon Polar Services Corporation (RPSC; they operate the bases). RPSC provides everything from laboratory space to food and fuel to transportation and internet access. The US Air Force chips in with flights to/from Antarctica.

At LBNL, we have focused on getting the prototype station hardware ready to go. The picture (above) shows Thorsten with the electronics box. It uses electronics from the ANITA balloon experiment, converted by Steve and his collaborators for use in ARIANNA. Steve provided new antennae, and we added new RF preamplifiers and lower powered GPS receivers and updated the Field Programmable Gate Array (FPGA) firmware. Lisa Gerhardt (LBNL) and Ryan Nichol(University College, London) wrote new software. Steve and his student, Jordan Hanson, even brought the solar panel, wind generator and associated tower up to LBNL and guided us through assembling it.

We also spent much time trying to think of everything that we will need in the field, since what we take is what we’ll have. There are no equipment piles, useful junk, or next-door labs to borrow an oscilloscope (or even a screwdriver).

We also had to undergo thorough medical and dental checkups, including many, many blood tests, and an EKG. There were also on-line courses on Antarctic ecology and adhering to the Antarctic treaty, and on computer security.

These preparations are the building blocks for a successful season; hopefully all of this work will pay off.

Why we are going to Antarctica

2009-11-23T14:05:00.001-08:00

This blog will be an account of my trip to Moore’s Bay, on the Ross Ice Shelf in Antarctica. Thorsten Stezelberger (an LBNL Engineer) and I are going there to study the site conditions and test prototype electronics for ARIANNA, a proposed experiment to look for radio pulses produced by neutrino interactions in the Antarctic ice. I will try to capture the adventure of traveling to Antarctica and camping out on the ice, while also giving you and idea of why this crazy trip is worthwhile, scientifically.

We plan to leave Berkeley on November 28^th, and fly via Christchurch, New Zealand to McMurdo Station, in Antarctica. There, we will attend “Snow School,” (aka survival training) and gather our equipment, before being deposited by helicopter on an empty patch of ice in Moore’s Bay, about 70 miles from McMurdo, where we will camp on the 650 m thick Ross Ice Shelf. We plan to spend 10 days in Moore’s Bay, characterizing the ice (e.g. measuring the radio wave reflections from the ice-water interface, etc.) and setting up a prototype radio detector which will be left in place for a year. Of course, plans sometimes change quickly in Antarctica.

The prototype is one step toward ARIANNA, a proposed array of about 10,000 stations, covering roughly 900 square kilometers. Each station will consist of 8 TV-like antennae embedded in the ice, connected to an electronics box containing trigger electronic and waveform digitizers. The whole thing will be powered by solar panels in the summer (when the sun is continuously above the horizon). For the winter, we are testing a wind generator, but this will place stringent limits on station power consumption.

The ARIANNA detectors search for radio waves produced by neutrino interactions in the ice. The radio pulses come from the particle showers produced when occur when the neutrino converts it’s energy into matter, creating a shower containing up to a trillion particles. The showers contain more electrons than positrons (because some of the photons Compton scatter from atomic electrons in the ice). The moving charges emit Cherenkov radiation. For radio wavelengths longer than the shower diameter, the radiation is coherent, producing large signals in the 50 MHz to 1 GHz frequency range. The signal size rises as the square of the neutrino energy; ARIANNA should detect neutrinos with energies above 10^17 eV.

We use these neutrinos to probe the high energy cosmos, to find the origin of the high energy cosmic rays that have been observed by surface air shower arrays like Auger. ARIANNA will complement smaller neutrino detectors like the 1 cubic-kilometer IceCube array which is optimized for lower energy (10^11 to 10^17 eV) neutrinos.

IceCube

2009-11-19T17:08:00.000-08:00

ARIANNA is in some sense a follow-on experiment to IceCube, a neutrino detector that is now being built at the South Pole. IceCube also looks for Cherenkov radiation from the charged particles produced in neutrino interactions. However, Icecube looks for visible light Cherenkov radiation, while ARIANNA looks for radio waves. IceCube is smaller than ARIANNA, and optimized for lower energy neutrinos.

The IceCube detector consists of one cubic kilometer of ice, just North (about 2 km) of the South Pole, where the ice cap is 2800 meters thick. We are building it (it's about 2/3 done) by drilling 86 holes, each 2500 meters (more than a mile) deep, using hot water to melt our way through the ice. We then lower strings of 60 very sensitive optical detectors into the holes, instrumenting the bottom 1,000 meters. LBNL built the data acquisition electronics for these modules, and is also very involved in the software, calibration and data analysis. Our main physics goal is to search for sources of high-energy (above 100 GeV) extra-terrestrial neutrinos. We also study a wide variety of other physics, ranging from searches for hypothetical particles like magnetic monoples, or different models of dark matter, to studies of the composition of cosmic rays. The latter study uses an array of surface detectors, IceTop to detect cosmic-ray air showers; we use the buried optical sensors to study high-energy muons in these showers. IceCube is being built to the right of the ski-way in this photo; the station living areas are to the left.

There are some photos here, a 'travelog' here, and links to other photo collections here.

n.b. I am editing this post on Nov. 27th,to fix a bad link, pointed out by Bob Stokstad.