Wednesday, November 27, 2013

Big Bird joins Bert and Ernie


Bert and Ernie have company!  IceCube has found another PeV neutrino, event more energetic than Bert or Ernie.   The pictures below shows the IceCube standard event display, with side and top views.  Unfortunately, some of the optical modules see so much light that you can’t see what’s happening near the neutrino interaction.  In fact, the photodetectors in the optical modules are badly saturated.  The two event displays below show the side and top views of Big Bird; the enormous hit in the nearby DOMs overwhelms the image.  Each colored sphere represents an optical module that observed light; the colors show the relative time of the hit, from red (earliest) through orange and yellow.  The size of the spheres shows the amount of light detected.

Like Bert and Ernie, it is well contained within the detector, with no sign of early hits that might signal an entering muon; it is quite clearly a neutrino induced cascade (particle shower).  


The event was found by LBNLs Lisa Gerhardt, on her last day working on IceCube, before she moved to a position focused on high-performance computing - still at LBNL, but now at the National Energy Research Supercomputer Center).   Talk about going out in style!

I was privileged to be able to first show this event at the 2013 International Cosmic Ray Conference (ICRC), in Rio de Janeiro, Jul2 2-9th.  I would have loved to blog about it earlier, but the only available reference is the writeup of my talk.  Because that writeup covers the evidence for extra-terrestrial neutrinos (my last two posts), we agreed not to post it publicly until the Science paper appeared.  Now that the Science paper is out, the writeup is available on the Cornell preprint server as arXiv:1311.6519.  
 

Unfortunately, the collaboration decided not to release any information on the event energy or direction, pending a systematic analysis, but it is a nice little monster.   As you should expect, we are working hard on these analyses, so I should be able to say more in the not too distant future.


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