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  • Development of a low backgr...
    Erchinger, J.L.; Aalseth, C.E.; Bernacki, B.E.; Douglas, M.; Fuller, E.S.; Keillor, M.E.; Morley, S.M.; Mullen, C.A.; Orrell, J.L.; Panisko, M.E.; Warren, G.A.; Williams, R.O.; Wright, M.E.

    Applied radiation and isotopes, 11/2015, Letnik: 105
    Journal Article

    Pacific Northwest National Laboratory has recently opened a shallow underground laboratory intended for measurement of low-concentration levels of radioactive isotopes in samples collected from the environment. The development of a low-background liquid scintillation counter is currently underway to further augment the measurement capabilities within this underground laboratory. Liquid scintillation counting is especially useful for measuring charged particle (e.g., β and α) emitting isotopes with no (or very weak) gamma-ray yields. The combination of high-efficiency detection of charged particle emission in a liquid scintillation cocktail coupled with the low-background environment of an appropriately designed shield located in a clean underground laboratory provides the opportunity for increased-sensitivity measurements of a range of isotopes. To take advantage of the 35m-water-equivalent overburden of the underground laboratory, a series of simulations have evaluated the scintillation counter's shield design requirements to assess the possible background rate achievable. This report presents the design and background evaluation for a shallow underground, low background liquid scintillation counter design for sample measurements. •Graded-shielding can produce an ultra-low-background liquid scintillation counter.•Location in a shallow underground cleanroom further enhances background reduction.•A novel light collection design and selected low background materials are utilized.•The background is predicted to be 10–100 times below typical commercial systems.•Simulations tentatively predict a background rate of order 10 counts per day.