Development of a low background liquid scintillation counter for a shallow underground laboratory

• Published in: arXiv.org 2015-12
• Main Authors: 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
• Format: Article
• Language: English
• Subjects: Alpha rays; Beta rays; Charged particles; Design analysis; Gamma rays; Laboratories; Measuring instruments; Particle emission; Radioisotopes; Rangefinding; Scientists; Scintillation; Scintillation counters
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1512.06477

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., \(\beta\), \(\alpha\)) 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 35 meters-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.