Thermal neutron detection with Resistive Plate Chambers via the ¹⁰B(n,α)⁷Li reaction

Resistive Plate Chambers for thermal neutron detection have been developed and prototypes of the detector have been built. A ¹⁰B₄C thin coating on the inner surface of one of the electrodes of the RPC is used as a thermal neutron converter via the ¹⁰B(n,α)⁷Li reaction. Monte Carlo calculations show that a conversion efficiency of about 2% for neutrons from a moderated beam can be achieved with a 3 μm ¹⁰B₄C layer. Converter coatings on glass plates have been tested with thermalised neutrons from a ²⁵²Cf source (INFN Laboratori Nazionali Legnaro). The energy spectra, measured with a Si detector for different converter thicknesses, are well reproduced by simulation. A prototype RPC, with 10 × 10 cm² glass electrodes and a 2 mm gap, has been built, characterised with cosmic rays and tested in avalanche mode with a low energy neutron beam at the european research centre IRMM (Geel, Belgium). A description of the prototype is presented, together with the results of experimental tests.