The radiation monitoring system of the Novosibirsk FEL
Accelerator recuperator FEL works in the following energy range: 1st FEL to 12 MeV, 2nd FEL - 20 MeV, 3rd FEL - 40 MeV. The electron beam current is about 10 mA. When the beam is lost on the walls of the vacuum chamber, the dose rate of bremsstrahlung reaches several kilo gray per hour. After recuperation, the beam (1.5 MeV) enters into the copper dump, the contribution to the dose rate from the dump reaches several hundred gray per hour. Radiation monitoring system FEL controls radiation in the working rooms and the acceleration hall. The three-meter concrete walls of the acceleration hall provide reliable protection, in neighboring rooms the dose rate does not exceed the maximum permissible levels. TLD dosimeters provide integrated dose monitoring, and ionization chambers provide real-time monitoring. At present, ionization chambers are being replaced by Geiger counters. Part of the sensors is in the acceleration hall. The sensors are placed in lead containers, and installed near the vacuum chamber. It makes it possible to build a profile of radiation levels along the vacuum chamber, and localize the places of beam losses. Several sensors are placed in check points, they are monitoring integral doses. Currently, it is planned to connect sensors that will monitor induced radioactivity. The software part of the system is based on Scientific Linux. It uses a distributed control system EPICS, which makes it easy to create client programs and data acquisition system. The server is implemented on the controller with CANbus interface, which is connected to the block controls radiation sensors.