CERN-RD39 collaboration activities aimed at cryogenic silicon detector application in high-luminosity Large Hadron Collider

Beam Loss Monitors (BLM) made of silicon are new devices for monitoring of radiation environment in the vicinity of superconductive magnets of the Large Hadron Collider. The challenge of BLMs is extreme radiation hardness, up to 10¹⁶ protons/cm² while placed in superfluid helium (temperature of 1.9 K). CERN BE-BI-BL group, together with CERN-RD39 collaboration, has developed prototypes of BLMs and investigated their device physics. An overview of this development—results of the in situ radiation tests of planar silicon detectors at 1.9 K, performed in 2012 and 2014—is presented. Our main finding is that silicon detectors survive under irradiation to 1×10¹⁶ p/cm² at 1.9 K. In order to improve charge collection, current injection into the detector sensitive region (Current Injection Detector (CID)) was tested. The results indicate that the detector signal increases while operated in CID mode. - Highlights: • Activities aimed at upgrading of Beam Loss Monitors (BLM) at HL-LHC are described. • Overview of in situ radiation tests of silicon BLMs immersed in LHe is presented. • Silicon detectors with 300 and 100 μm thickness survived radiation at 1.9 K. • Current injection is still effective at 1.9 K for radiation hardness improvement. • Si detectors are currently installed on the magnets for their operation as BLMs.