A microdischarge-based neutron radiation detector utilizing sputtered gadolinium films for neutron conversion

Microfabricated detectors can be used to provide first alert information about the presence of radiation sources. This paper describes a miniature Geiger-Muller microdischarge-based device that can be used to detect neutrons. The detector uses thin film gadolinium (Gd) layers to convert thermal neutrons into fast electrons and gamma rays which are then detected by gas breakdown. The detector electrodes are lithographically micromachined from stainless steel 304, stacked in a cathode-anode-cathode arrangement, separated by spacers, and assembled within a commercial TO-5 package. The detector diameter and height are 9 and 9.6 mm and it weighs 0.97 g. The detector performance is characterized using two sealed isotope sources ²⁵²Cf (which is a neutron and gamma emitter) and ¹³⁷Cs (which is a pure gamma emitter). The detector is tested in an Ar environment at atmospheric pressure and applied bias of 285 V. For a 90 μCi ²⁵²Cf neutron source placed at a distance of 10 cm from the detector, total neutron count rate was typically 8.7 counts per minute (cpm) with background radiation of 1.2 cpm.