SND@LHC: beam test at CERN
"From 2 to 16 August, the SND@LHC collaboration was at CERN's North Area calibrating the detector, and the LIP team had a central role. This is a fundamental step towards measuring the energy of the first neutrinos detected at the LHC."
The SND@LHC experiment recently published its first results: the first observation of neutrinos in particle collisions in an accelerator. We know that these neutrinos have high energies, but they have never really been measured directly. The next objective of the experiment is therefore to measure the energy of these neutrinos!
The SND@LHC experiment is in its first year of operation and was built and installed in record time. There is still work to be done before this measurement is possible: the detector must be calibrated, i.e. one needs to understand how to obtain the energy of the incident particle from the energy deposits in the detector. This is usually done by measuring the detector's response to a beam of particles whose energy we know.
For a fortnight, from 2 to 16 August, the SND@LHC collaboration was in CERN's North Area calibrating the detector's hadronic system. Beams of pions and muons with energies relevant to the processes that will me measured at the LHC were used. Of course, it was not the SND@LHC detector installed in the LHC tunnel (TI18) since the summer of 2022 that was brought to the North Area. Instead, an analogue system containing an exact replica of the hadronic system was used, preceded by iron interspersed with cintillating fibres, which simulates the effect of the tungsten/emulsions sandiwch existing in the real detector.
The LIP team played a central role in these beam tests, as has been the case throughout the project - from the construction of the mechanical structure of the hadronic system in the LIP Mechanical Workshop in Coimbra to the assembly and commissioning of the detector in situ, and later in data collection, quality control and analysis. This summer, Guilherme Soares, PhD student at LIP and IST, was part of the core team at CERN and played a key role in the calibration data taking.
The campaign was a success and more data was collected than initially planned. The experiment is now one step closer to making the first measurement of the energy of neutrinos coming from the LHC.