LHCf completes its first run

LHCf, one of the three smaller experiments at the LHC, has completed its first run. The detectors were removed last week and the analysis of data is continuing. The first results will be ready by the end of the year.


One of the two LHCf detectors during the removal operations inside the LHC tunnel.

LHCf is made up of two independent detectors located in the tunnel 140 m either side of the ATLAS collision point. The experiment studies the secondary particles created during the head-on collisions in the LHC because they are similar to those created in a cosmic ray shower produced when a cosmic particle hits the Earth’s atmosphere. The focus of the experiment is to compare the various shower models used to estimate the primary energy of ultra-high-energy cosmic rays. The energy of proton-proton collisions at the LHC will be equivalent to a cosmic ray of 1017eV hitting the atmosphere, very close to the highest energies observed in the sky. “We have now completed the first phase of our research programme”, says Oscar Adriani, LHCf Deputy Spokesperson. “The experiment has been designed to work with high-energy particles but at a low luminosity. The LHC is now increasing the luminosity, which can cause problems for our detectors. At the same time, we have now collected enough data at 450 GeV and 3.5 TeV per beam”.

The detectors that LHCf used for this first run were mainly plastic scintillators. The collaboration will now work on replacing them with more radiation-resistant crystal scintillators, to be ready by 2013 when the LHC will run at 7 TeV per beam. The collaboration also plans to change the position of its silicon detectors to improve the performance of the experiment in measuring the energy of the interacting particles. “It was an advantage for us to be able to collect data at lower energies as this will allow us to compare the theoretical models also at these intermediate energy regions. The UA7 experiment carried out at the SPS accelerator in the 1980s already provided information for 450 GeV energy collisions. LHCf will be the first to provide results at 3.5 TeV and beyond”, confirms Adriani. The results of the data analysis at 450 GeV will be available by the end of the year, while data at 3.5 TeV will be analysed in 2011.


by CERN Bulletin