Speaker
Description
Position Sensitive Neutron Detectors (PSNDs) play a critical role in many fields, such as neutron scattering science (NSS), homeland security and well logging. During the last decades these detectors were mainly based on the 3He isotope, the golden standard for thermal neutron detection. Nowadays, however, the 3He crisis resulted in a change of paradigm which poses demanding challenges to develop new types of neutron detectors, capable to satisfy high performance standards. A 3He free position sensitive thermal neutron detector concept which combines the well established Resistive Plate Chambers (RPCs) technology with 10B solid neutron converters has been developed at LIP. Here we report results of a feasibility study of a 10B based thin-gap RPC detector prototype. The high quality boron carbide coatings enriched in 10B were manufactured at the European Spallation Source (ESS) Detector Coatings Workshop in Linköping. The prototype features a thin-gap Hybrid RPC with a metallic cathode coated with a layer of boron carbide enriched in 10B (2 microns thick). The sensitivity to the thermal neutrons is achieved by the nuclear reaction 10B (n, alpha) 7Li through the ionization caused by the fission fragments that reach the gas-gap of the RPC. A PCB with an engraved array of signal pick-up strips, facing the outermost surface of the resistive anode, was read-out by a MAROC3 ASIC. Event positions were determined in one dimension using the Center of Gravity method and the recorded signals amplitude read from individually strips. Experimental results from the tests of the detector on a monochromatic thermal neutron beam at the Institut Laue-Langevin (ILL) will be presented. An extended plateau was observed in the measurement of the count rate versus high voltage. A spatial resolution better than 1 mm FWHM was measured, demonstrating the viability of 10B based thin-gap RPCs for PSNDs with sub-millimeter resolution. The influence of the 4He and 7Li fission fragments ranges in the gas-gap on the spatial resolution will be discussed based on MC simulations. We also present a concept of a 10B multi-layered detector based on a Multi-Gap RPC which is currently under development in the frame of the SINE2020 EU project.
