Portable Gamma and Neutron Radiation Dosimeter Reader

Abstract

During the operation of linear accelerators, gamma and neutron radiation is produced. Gamma radiation causes semiconductor degradation. Therefore, it is necessary to replace electronic devices when the maximum allowed dose is reached to ensure reliable operation of the accelerator. Neutron radiation causes soft errors in memories and registers because of Single Event Upsets (SEUs). This may disturb the whole accelerator operation. Because of this, radiation monitoring in linear accelerator tunnels is recommended. A portable dosimeter reader was designed and build. Because gamma and neutron radiation can cause different effects in electronic devices and different way of protection against this two types of radiation are applied, this two types of radiation should be measured selectively. Three different types of dosimeters are used: gafchromic films (gamma radiation), SRAM-based dosimeters (neutron radiation) and LED-based dosimeters (neutron radiation) to ensure selective measurement. All methods need dedicated reading electronic circuitry. Nevertheless, a single readout device was designed. The device was calibrated and tested in the FLASH environment at DESY. Radiation doses, near the ACC2 module and bunch compressor were measured. The device is expected to be regularly used in currently built at DESY European X-Ray Free Electron Laser (XFEL).