Birmingham Particle Physics research group successfully completed a pilot run of the NA62 experiment at test facility CERN on Monday 15 December 2014. The experiment is a continuation of the very successful charged and neutral program at CERN which started with NA48.
The experiment interrogates The Standard Model of particle physics (SM), which fully describes high energy interactions in normal matter, as witness the discovery of the Higgs-like boson at LHC at CERN. But it doesn't explain dark matter or dark energy. Two approaches pursued in particle physics to search beyond the SM are the direct search for new particles at high energy (ATLAS and CMS experiments at LHC, for example), and the study of rare decays precisely predicted by the SM. The NA62 experiment at CERN is designed to pursue this second approach by precisely measuring the decay of a particle containing the strange quark. This particle is called the charged "kaon”: The charged Kaon can decay into a pion and two neutrinos; a process predicted by the SM to occur only once for every ten billion times that a Kaon decays. The SM decay rate has been computed with 10% relative precision.
This decay is an ideal place to search for new physics: the low and precisely predicted branching ratio of this decay mode means that any new physics signal will give a sizable deviation that will be detectable by the NA62 experiment.
The system of detectors for NA62 takes up 270 metres in an underground cavern at CERN, and is designed to recognise Kaons, and to measure different types of particles that can be produced in their decay. About fifty million Kaon mesons are produced per second, together with another billion pions and muons, by more than one thousand billion protons per second.
Dr Cristina Lazzaroni, Reader in Particle Physics, School of Physics and Astronomy, explains the project:
The main aim was to find something different from the prediction to help us to explain why the SM works so well and to understand how to improve it. The pilot run on 15 December 2014 was the first time the whole experiment was put on a beam line. The purpose of the first run is to take data and verify the correct functioning of all the elements of the systems, such as the detector, the trigger, and the data acquisition system. A key ingredient is the detector that identifies particles on the beam line, called KTAG. The University is responsible for the electronic system. associated with extracting the physics information.
We are very pleased to say that KTAG performed exceptionally well, exceeding the design specifications. The data indicates the detector performed very well, so we will use this to tune and optimise the system for the physics run in 2015. The excellent performances of KTAG are fantastic achievements at the end of several years of hard work. I'm really pleased we exceeded specifications and we are very excited about taking data for physics in the years to come.
The Birmingham group is one of the largest in the NA62 collaboration, and is involved in:
- construction and operation of the CEDAR/KTAG Cherenkov detector;
- development and operation of the L0 muon trigger system;
- development and support of the run control system;
- development and support of the core software;
- measurements of lepton flavour and lepton number violating kaon decays;
- lepton universality tests in leptonic kaon decays;
- rare kaon and pion decay measurements.