Position sensitive GEM-based neutron detector prototype

Abstract

In response to the 3He shortage [1], alternatives for thermal neutron detection are being pursued nowadays. Elements such as 157Gd, 10B and 6Li are commonly used to substitute 3He due to their high neutron capture cross section. In this work, we present our thermal neutron detector prototype, which makes use of 10B as converter. This detector works under Ar/CO2 (90/10) open flux and uses two gas electron multipliers (GEMs) [2] microstructures to multiply the charge signal. The neutrons are detected through the gas ionization generated by the products of the 10B(n; a)7Li reaction. The neutron capture takes place in the inside face of the aluminum cathode, which is coated with a 2:2 μm thick 10B4C layer (deposition kindly provided by the European Spallation Source (ESS) laboratories). Experimental measurements obtained in the IEA-R1 nuclear research reactor, at the Nuclear and Energy Research Institute (IPEN), shown that our prototype presents high stability, position sensitivity with spatial resolution better than 3mm and an efficiency of 2.97(25)%, allowing its application as beam profiler. Methods to increase the neutron detection efficiency will then be discussed.