Commercialization of the Li-Foil Multi-Wire Proportional Counter Neutron Detector, a Backpack Radiation Detector Design

Abstract

Large-area neutron detectors as a cost-effective alternative to 3He continue to be explored. The Lithium Foil Multi-Wire Proportional Counter Neutron Detector (Li-Foil MWPC) is currently commercially available with complete electronics and readout software. The standard module was designed around a backpack, or portable, configuration, but can be customized to a specific application/system. The standard module consists of four - 6Li-enriched foils, two suspended and two along the walls of the device. The four-foil design results in a 39.2% thermal neutron detection efficiency and has approximately a 16inch x 2inch active detection area per device [1]. The device design results in a thermal neutron sensitivity of approximately 80.9 cps/nν, which is comparable to a 1.5atm 3He device of approximately equal active area (18inch length x 2.0inch diameter) with a thermal neutron sensitivity of approximately 85 cps/nν. The Li-Foil MWPC has an electronics package with microphonic rejection firmware coupled with each device that is customizable with a user-specified electrical interface, such as USB or M8. Including the electronics package, the standard device size is 19.5inch x 2.205inch x 1.375inch and weighs less than 1.6 lbs. The electronics package requires 2.7 – 4.5 volts input and has approximately a 400mW power draw. A backpack radiation detector (BRD) was built using a three-device Li-Foil MWPC configuration and was sent to PNNL for a test campaign. The angular sensitivity to a 252Cf source calibrated to irradiate the Li-Foil BRD with 1 n/cm2-s was measured from zero to 180 degrees in 45-degree increments. The neutron sensitivity to various neutron sources including 252Cf, AmBe, AmLi, and WGPu was also measured. Lastly a gamma-ray rejection ratio of 1.83 x 10-8 ± 2.83 x 10-9 for 60mR/hr of 60Co was measured, and an Absolute Gamma-Ray Rejection in the Presence of Neutrons (GARRn) of 1.00 ± 0.0036 was also measured.