ИСТИНА

Monitoring of neutron radiation field is an important task for the CMS experiment at CERN. Neutron background affects electronics situated in the experimental cavern inducing single event effect (SEU, SEL etc). In addition, neutron flux is a main source of the background for the muon chambers, so it affects both performance and longevity of the detectors, especially for high luminosity operation. Therefore, we need a distributed system of neutron monitors around the shielding and in proximity of the detector/electronics components. SiPM based detector could be considered as good candidate for monitoring of CMS neutron background. Several types of available neutron detectors with SiPMs coupled to neutron sensitive scintillators ZnS:Ag/6LiF and LiI(Eu) produced by different firms and research centers were considered as a prototypes for such task. These prototypes were calibrated at CERN lab with neutron- and gamma-sources and tested in CMS experimental cavern at several levels of luminosity with and without polyethylene moderator.