Imaging the Earth with Neutrinos

 Hi again,

As the Russian invasion of Ukraine continues (with, to my mind, uncertain results), the four CERN LHC experiments still have no agreement on papers with Russian co-authors.  Since early March (6 months ago), the experiments have been submitting papers to the Cornell preprint server with only collaboration names - no individual authors.   These 'nameless' papers are being refereed by journals, and doubtless some of them are ready for publication, lacking only a specific list of author names, and likely affiliations.  

The world of neutrino astronomy has also been pretty quiet.   The RNO-G deployment season in Greenland is winding down, apparently quite successful.  There was an interesting two-day (Saturday and Sunday) meeting at "NuFact 2022" on the use of neutrinos to image the interior of the Earth.  There are two techniques that can be used.  The first is to look for neutrino absorption in the Earth, as we have discussed before.  The second is to study neutrino interactions with the electrons in the nuclei in the Earth.  These electrons are seen as effectively a large cloud, and electron-flavored neutrinos interact with the cloud differently than muon-flavored and tau-flavored neutrinos.  This affects how neutrinos oscillation - this is known as matter-induced oscillations.   The affect depends on the electron density, so oscillations can serve as a complementary approach to neutrino absorption.