부산대학교 도서관

Hadron fluence monitors based on static random access memories (SRAMs) are being used at CERN and have been proposed for proton therapy facilities. Some of the limitations of the state of the art are related to the usage of separate components for sensing upsets and for reading them out, as these increase the power consumption, the board complexity, and its size. Moreover, in some cases, due to radiation-tolerance requirements, the readout logic (ROL) is fixed, and it cannot be updated once the system has been implemented. In this work, we show how to overcome the mentioned limitations by using an SRAM-based field programmable gate array (FPGA) for implementing both the sensitive element [the configuration SRAM (CRAM)] and the ROL (the firmware in the fabric). In fact, we describe the implementation of a compact, reprogrammable, low-power, actively self-reading hadron fluence sensor realized by means of a Xilinx Artix-7 FPGA. Moreover, we present the customized radiation-hardening-by-design (RHBD) techniques adopted for the ROL. We irradiated two sensor prototypes at the Jožef Stefan Institute ’ s TRIGA Mark II research reactor, under different neutron spectra and flux conditions. We discuss our results, which include the measurements of the radiation tolerance, the single event upset (SEU) cross Section of the CRAM, the sensitivity to thermal neutrons, and the failure cross Section of the ROL.