Prof. Amanda Cooper-Sarkar, St Hilda’s Fellow and Tutor in Physics is a member of the ATLAS experimental collaboration at CERN, which recently discovered the Higgs Boson, see http://www.atlas.ch/news/2012/latest-results-from-higgs-search.html.
She says: 'It has been pretty exciting for the last few weeks. I first realised that we might have it on June 18th when I saw some plots from the Higgs group which showed that the small signal we saw last year was seen again in this year's data. We were then under great pressure to confirm this before the big particle physics conference of the year in Melbourne, starting July 4th. In fact we had only analysed about half of the new data- analysis takes some time. The Higgs is hard to see because it decays quickly. We decided to concentrate on two of its decay modes- Higgs to two photons and Higgs to two Z bosons. These are the cleanest channels. By June 26th the signal had got even stronger and we were getting pretty excited- but we did not know whether our findings were confirmed by the other experimental collaboration CMS. I went to a mini-workshop in Cyprus from June 26th-28th where members of both collaborations were present but we had all been sworn to secrecy. Nobody broke this, but there was something about the happy expressions which made me confident.
I was having dinner with friends on the night of June 30th when I received notification though my phone that our results had reached the required statistical significance for a discovery- but still we were not allowed to say anything until the morning of July 4th when an official announcement would be made by both collaborations from CERN and broadcast directly to the Melbourne conference. That morning the lecture theatre in the Denys Wilkinson Building, Keble Rd was packed at 8am to hear the live broadcast. Spontaneous applause broke out as the evidence was revealed to be equally strong in both experiments.
This is a discovery because it has a statistical significance (called 5 sigma significance) such that there is only a one in a million chance that the signal could be generated randomly. Secondly because the signal is seen by two independent experiments ATLAS and CMS which agree on the significance of their signals and on the mass of the Higgs Boson- 126GeV or 134 times the mass of a proton.
Prof. Peter Higgs was in the audience at CERN and was visibly moved to tears as he saw the confirmation of his work. Somehow we all felt the same sense of achievement. Oxford has played a pivotal role in the discovery both in the analysis and in the construction of the central part of the ATLAS detector which was built here in Oxford and shipped to CERN.'