Development of radiation hard sensing fibres for FLASH therapy and the CERN Experimental Areas

The north experimental area at CERN is undergoing a major upgrade in its beam instrumentation. In this project work has been done on fibers for use in a radiation hard beam monitor, which in addition to use in the North experimental area can potentially also be used as instrumentation for FLASH therapy, as well as a scintillating tile to be added as a trigger to the XBPF beam monitor. Scintillating fibers as well as solid core optical fibers were tested, first with a strontium-90 source and then in the CLEAR facility at CERN. The readout chain was developed and consisted of a silicon photomultiplier, an amplifier, a digitiser and a PC. Initial results show great promise with respect to the light-yield achievable. Tests in CLEAR show promising linearity with increasing dose delivered to the fiber. The scintillating tile was simulated in GEANT4 and a prototype was constructed in the lab. Test with a Strontium-90 source show a high possible efficiency.