Resistive Plate Chambers as thermal neutron detectors

We present a construction procedure suitable to make Resistive Plate Chambers detectors sensitive also to thermal neutrons. This procedure, consisting in coating the inner surface of one of the RPC bakelite electrodes with a mixture of linseed oil and Gd2O3, is very simple, cheap, and suitable to be employed for industrial, medical or de-mining applications. Here the results of extensive tests aimed to asset the performance of two prototypes of Gd-RPCs are shown. While the detection efficiency to thermal neutrons for a standard not Gd-coated RPC results to be about 0.1%, Gd-RPCs reach, in stand-alone, absolute efficiencies of about 10%, and, when two of these detectors are coupled together, more than 15%. In addition RPCs have excellent time resolution and good imaging performance. This new type, position sensitive gas detector can be operated at atmospheric pressure, is light-weighted, has low gamma-ray sensitivity, and is easy to build and handle even when large areas are to be covered.