Design of the beam loss monitoring system in strong prompt radiation field

It is inescapable that some electrons will be lost when they are accelerated or transported in the accelerator vacuum chamber. A beam loss monitoring (BLM) system, which works by the radiation measurement, has been successfully installed on the storage ring. Next on the schedule is design of the BLM system for LINAC and transport line. The radiation field around the LINAC and transport line consists of a strong prompt mixed (gamma, neutron) one. Its duty factor is only 10−6 at Hefei Light Source (HLS). A detector based on counting cannot be used here, while one based on integral charge may be suitable in such a field. The most effective detected objects for estimating beam loss by radiation measurement are shower electrons because they can indicate the beam loss position more clearly than γ rays. The detector also should have the ability to decrease stray radiation influence in strong prompt radiation field. For the requirements mentioned above, a new kind of photodiode detector is being developed. We analyzed the beam transportation process and calculated relevant parameters. Then the positions where the detectors should be fixed were determined. The CAN bus mode we use for the storage ring BLM system is out of date because of the rapid development in the communication field. TCP/IP communication is used for the new system.