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A 3He beam stop for minimizing gamma-ray and fast-neutron background



Danyal J. Turkoglu, Robert G. Downing, Wangchun Chen, Dagistan Sahin, Jeremy C. Cook


Prompt gamma-ray activation analysis facilities with high neutron currents (≥109 s-1) generate triton-induced fast neutrons from 6Li-loaded collimators and beam stops at rates that soon damage gamma-ray detectors. We develop an alternative beam stop design using 3He gas that produces negligible gamma-ray and fast-neutron background following neutron absorption. Replacing a 6Li glass beam stop with a test cell containing 2.5 MPa·cm of 3He reduced fast neutron production by 73%. An optimal 3He beam stop design with a 100-µm-thick entrance window, modeled using MCNP6, enables operation of detectors closer to the beam stop.
Journal of Radioanalytical and Nuclear Chemistry


prompt gamma-ray activation analysis, instrument design, Monte Carlo radiation transport, neutron shielding, gamma-ray background, helium, lithium, boron


Turkoglu, D. , Downing, R. , Chen, W. , Sahin, D. and Cook, J. (2016), A 3He beam stop for minimizing gamma-ray and fast-neutron background, Journal of Radioanalytical and Nuclear Chemistry, [online], (Accessed April 20, 2024)
Created August 6, 2016, Updated November 10, 2018