Neutron beam monitor based on a boron-coated GEM

A new thermal neutron beam monitor with a Gas Electron Multiplier （GEM） is developed to meet the needs of the next generation of neutron facilities. A prototype chamber has been constructed with two 100 mm×100 mm GEM foils. Enriched boron-10 is coated on one surface of the aluminum cathode plate as the neutron convertor. 96 channel pads with an area of 8 mm×8 mm each are used for fast signal readout. In order to study the basic characteristics of a boron-coated GEM, several irradiation tests were carried out with of source ^239pu and neutron source ^241Am（Be）. The signal induced by the neutron source has a high signal-to-noise ratio. A clear image obtained from of source ^239pu is presented, which shows that the neutron beam monitor based on a boron-coated GEM has a good two-dimensional imaging ability.

A new neutron detector based on ceramic THGEM and boron-coated meshes

Introduction Boron-coated micro-pattern gaseous detectors,such as gaseous electron multiplier(GEM),are widely studied as the neutron detectors.The existing solution to improve the neutron detection efficiency(NDE)is to coat the boron on the surfaces of the cascade GEM films.So the GEM films themselves will be affected by the complicated coating process and the boron layers,and the 10B material will be wasted once the GEM films are damaged.Since the neutron conversion and the electron multiplication regions are not separated,the final gains of different layer ionized electrons are very difficult to control and keep consistent.Materials and methods A new neutron detector based on the ceramic thick GEM(THGEM)was proposed.The boron-coated cathode and multilayer meshes were used as the neutron conversion region and separated from the electron multiplication region consisting of only one THGEM film.The sawtooth surface treatment and the double-sided readout method were applied to improve neutron conversion efficiency(NCE).The neutron conversion and the electron collection efficiencies were simulated and studied based on the new structure.The prototype detector was test by using a ^(252)Cf neutron source.Results The simulation results show that the cascade boron-coated meshes have good neutron conversion and electron collection efficiencies,and the double-sided readout and sawtooth structure can greatly increase the NCE.The neutron test results show that the detection efficiency of the double-sided readout is 1.6 times higher than that of the common single-sided readout.These indicate that the new detector has high neutron conversion and detection efficiencies and is promising for practical applications.