Study of the background components for a Ge(HP) detector in environmental radioactivity measurements

doi:10.1016/0168-9002(94)91821-X

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

Volume 339, Issues 1–2, 22 January 1994, Pages 297-301

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Abstract

A quantitative study of the environmental background components of a gamma-ray spectrum recorded with an unshielded p-type germanium detector has been performed. The contribution of each component to the background spectrum was analyzed separately using Monte Carlo simulation techniques.

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Cited by (3)

A low background gamma-ray spectrometer with a large well HPGe detector
2020, Applied Radiation and Isotopes
Citation Excerpt :
Cosmic-ray induced isomers with longer half-lives than the coincidence time interval are observed in the spectra. Details of those common background components and their production processes, by interaction between cosmic rays and surrounding materials, are well summarized elsewhere (Sánchez et al., 1994; Heusser, 1996; Núñez-Lagos et al., 1996; Cannizzaro, 1997; Michael, 2003). Integral counting rates within an energy range between 40 keV to 3000 keV with and without anti-cosmic mode were 0.337 s-1 and 1.51 s-1, respectively.
A low background gamma-ray spectrometer was established in a ground-based laboratory. It consists of a large well (diameter: 28 mm, depth: 40 mm) HPGe detector and an anti-cosmic shielding system. The photon background of the present system was measured with and without the anti-cosmic mode, and compared with each other, and the detection capability with the detection efficiency calibration was estimated. The background with passive and active shields for the energy region between 40 keV and 3000 keV was reduced by 78% compared to one with just passive shield. The full energy peak efficiency for cylindrical samples with three different heights and the minimum detectable activity of the present system were tabulated for main radionuclides to be measured in environmental monitoring.
An anticoincidence-shielded gamma-ray spectrometer for analysis of low level environmental radionuclides
2003, Applied Radiation and Isotopes
We developed an ultralow-level background gamma-ray spectrometer, using active and passive shield devices at the same time. Cosmic-ray-induced background is suppressed by means of active shield devices consisting of plastic scintillating plates of 50 mm thick and anti-coincidence electronic system. The observed background rate was 0.34 s⁻¹ (=0.12 s⁻¹ per 100 cm³ Ge volume) for energy regions between 50 and 3000 keV. The detection efficiency curve for 10³ ml Marinelli beaker samples is obtained over all the energy regions. The advantages of the method are demonstrated by measuring the activity of ¹³⁷Cs in powdered milk sample prepared without taking any chemical procedure. The MDA for ¹³⁷Cs is estimated to be (17±1.7) mBq at a confidence level of 95% and it is about a factor of 10 lower than the MDA obtained from the previous cryostat assembly with 10-cm thick lead shielding.
Detection limits of the NaI(Tl) shielded HPGe spectrometer
1999, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
The results of a detailed study of the low-level performance of a NaI(Tl) shield added to an iron shielded HPGe spectrometer are presented. Both the “slow” and the “fast” anticoincidence gating modes were tested, the “slow” mode being found better suited for general low-level spectroscopy applications. In long runs the stability of the system in this mode is satisfactory. The anticoincidence action of the NaI(T1) shield lowers the integral background of the iron shielded HPGe detector in the energy range from 30 keV to 2 MeV by a factor of 6.5, and suppresses the continuum above 150 keV by a factor larger than 10.

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Study of the background components for a Ge(HP) detector in environmental radioactivity measurements

Abstract

Nucl. Instr. and Meth.

Nucl. Instr. and Meth. A

Nucl. Instr. and Meth. A

Nucl. Instr. and Meth. A

Nucl. Instr. and Meth. B