Recent progress in the commercialization of the Li Foil multi-wire proportional counter neutron detectors. (February 2019)

• Record Type: Journal Article
• Authors: Montag, Benjamin W.; Bellinger, Steven L.; Edwards, Nathaniel S.; Lage, Jackson; Nelson, Kyle A.; Henson, Luke C.; McGregor, Douglas S.
• Is Part Of: Radiation physics and chemistry. Volume 155(2019:Feb.)
• Page Start: 158
• Page End: 163
• Publication Date: 2019-02
• Subjects: Backpack radiation detector (BRD) -- Neutron detector -- Lithium foil -- Gamma-ray rejection; Radiation chemistry -- Periodicals; Radiometry -- Periodicals; Radiation -- Periodicals; Chimie sous rayonnement -- Périodiques; 539.2
• DOI: 10.1016/j.radphyschem.2018.08.003
• Languages: English
• ISSNs: 0969-806X

Abstract

Abstract: The scarcity and rising cost of 3 He gas has introduced a push in alternative neutron detector technologies. The Li foil multi-wire proportional counter (Li Foil MWPC) neutron detectors have shown promise as a 3 He replacement technology. Large, gas-filled proportional counters with five layers of 75 µm thick 6 Li foils have been built and characterized, yielding over 55% thermal neutron detection efficiency, with the possibility of increasing the efficiency above 70% with ten 96% enriched 6 Li foil layers. Most recently, a backpack radiation detector (BRD) was fabricated, equipped with four Li Foil MWPC devices. The neutron sensitivity-to-weight ratio of the Li Foil MWPC devices was first optimized using MCNP6 by simulating the angular response to an ANSI-moderated- 252 Cf source positioned 1.5 m away from the devices. The simulated neutron sensitivity results were compared and benchmarked to that of the commercially-available Thermo-Fisher PackEye v. 1.0 that contains two 14 in. long, 2 in. diameter, 2.5 atm 3 He tubes. The experimental efforts studied the performance of the Li Foil MWPCs in the backpack instrument configuration. Fabrication advancements were implemented to the Li Foil MWPC devices to increase the device manufacturability and improve the commercialization capabilities. These advancements included weight reduction, new hermetic sealing techniques, optimizing active area, and anode wire cost reduction. The Li Foil MWPC BRD was evaluated as a part of a PNNL test campaign for neutron sensitivity where 0.36 cps/ng of 252 Cf at 1.5 m was measured. The gamma-ray rejection ratio (GRR) of the BRD was also evaluated, yielding a measured value of 3.1 × 10 −8 for a 137 Cs exposure rate of 50 mR/Hr. Further evaluations were performed under the PNNL test campaign including detector response to neutron sources of 252 Cf, AmBe, AmLi and WGPu, detector angular response, and the gamma absolute rejection ratio in the presence of neutrons (GARRn). Highlights: A Li Foil MWPC backpack radiation detector (BRD) was fabricated. The neutron sensitivity-to-weight ratio of the Li Foil MWPC devices was optimized. The Li Foil MWPC BRD was evaluated at a PNNL test campaign. Neutron sensitivity was measured at 0.36 cps/ng for 252 Cf at 1.5 m. Gamma-ray rejection (GRR) was measured at 3.1 × 10 −8 for 50 mR/Hr 137 Cs.