Characterization of the neutron induced single event upset in SRAM around high megavoltage clinical accelerators

Linear accelerators for medical purposes represent a source of photoneutron radiation at high energy photon therapy modalities. In this clinical scenario, measurement of the neutron radiation field is a demanding task due to the high in-room photon fluence and its pulsed time structure. The interaction of neutrons with SRAM memory cells can produce upsets in the memory state. This effect has been exploited to produce a device composed of this type of memories used as a neutron detector. This device is mainly sensitive to low energy neutrons, and has been characterized previously in different dedicated experiments in calibrated beam and neutron sources. It has been proposed to estimate the neutron production strength of a medical linac and subsequently the patient neutron exposure during a treatment. The purpose of this work is to study the SRAM device dependence with gantry position and detector location inside a treatment room. These results reflect the neutron fluence variation inside a radiotherapy installation.