Some readers may remember that back in May, as I discussed in some detail, the IceCube experiment reported a new and exciting observation — possibly the first discovery of high-energy astrophysical neutrinos: neutrinos, with energies 5 – 50 times higher than those of the protons at the Large Hadron Collider, created in outer space and arriving on earth. This is to be contrasted with most neutrinos measured at IceCube and other previous similar experiments, which have lower energy and are created in the earth’s atmosphere by other types of particles hitting atoms in the air (see Figure 4 of this article.) Specifically, where the IceCube folks expected to measure 10 candidate events from non-neutrino backgrounds, they instead measured 28. Well, these results were reported at a conference in May, but only now is the paper appearing in published form, in the journal Science.
Here’s the IceCube press release about the publication of their paper, http://icecube.wisc.edu/news/view/171 . All indications are that there are few changes since May, except for greater confidence in the result; the numbers quoted all match the ones that I wrote about back in the spring. If there is anything strikingly different from May, I haven’t yet noticed it; please let me know if you’re aware of something.
For those of you who missed this back in May, I wrote a few relevant posts back then that you may find useful.
Meanwhile, you may also remember that there was a big Gamma Ray Burst [GRB] observed in April — the most energetic ever measured. [We were hoping that IceCube would observe neutrinos from that GRB, but it did not.] Science is also publishing papers about that event, and how measurements of it are making people rethink their understanding of how GRBs occur. Once I’ve learned more about this, I’ll post something more detailed.
Curiously, both of these stories are appearing in the press with big headlines, as though they are new news… but if they sound familiar, it’s because they are indeed six months old.