Davide Brundu

Operation of silicon photomultipliers at liquid helium temperature

We have investigated the performance of a few silicon photomultipliers to readout inorganic scintillators operated at cryogenic temperatures. Such detectors, that would need to operate close to liquid helium (LHe) temperatures and in a magnetic field of a few Tesla, have been proposed by our group as a way to build an active polarized target to be used for neutrino physics, for the search of axions and CP violation, as suggested by some theoretical papers. In the present work we investigate in some details the performance of a few different silicon photomultipliers produced by Hamamatsu and Advansid down to liquid helium temperature, to verify the temperature range of usability of these devices and their performance at cryogenic temperatures.

Measurement of the front-end dead-time of the LHCb muon detector and evaluation of its contribution to the muon detection inefficiency

A method is described which allows to deduce the dead-time of the front-end electronics of the LHCb muon detector from a series of measurements performed at different luminosities at a bunch-crossing rate of 20 MHz. The measured values of the dead-time range from 70 ns to 100 ns. These results allow to estimate the performance of the muon detector at the future bunch-crossing rate of 40 MHz and at higher luminosity.