Muon and neutron-induced background in gamma-ray spectrometry

• Published in: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment Vol. 652; no. 1; pp. 326 - 329
• Main Authors: Haines, D.K., Semkow, T.M., Khan, A.J., Hoffman, T.J., Meyer, S.T., Beach, S.E.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.10.2011
• Subjects: Background; Cosmic rays; Counting; Detectors; Environmental radioactivity; Gamma spectrometry; Germanium; Muons; Shielding; Spectrometers; Spectroscopy; Structural steels; Environmental radioactivity; Background; Cosmic rays; Gamma spectrometry
• ISSN: 0168-9002; 1872-9576
• DOI: 10.1016/j.nima.2011.01.137

A low-background γ-ray spectrometer for environmental surveillance, emergency response, and environmental health research has been constructed. It consists of a 132% efficient HPGe detector, graded lead shielding, and muon-rejection shielding, as well as external steel and building shielding. Detailed operation of the γ spectrometer and all of its components is described. Cosmic-ray muon and cosmic–neutron-induced background was accurately measured, and is discussed. We have achieved an overall background reduction by a factor of 9436 relative to the ambient level. Our integrated background rate in the γ energy range of 50–2700 keV was measured as 2.3 counts per min, corresponding to 15 counts ks −1 kg −1 Ge. Future directions in low-background γ spectroscopy at our facility are described.