Background shielding by dense samples in low-level gamma spectrometry

Thiesse, M.; Scovell, P. R.; Thompson, L.

doi:10.1016/j.apradiso.2022.110384

Cited by 4 publications

(1 citation statement)

References 16 publications

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“…In its current configuration, Merrybent is not achieving the lowest background possible for late chain 238 U due to what is believed to be contamination in the shield. Several assays with large, dense, and radiopure materials give counts in the 214 Pb and 214 Bi peaks at rates below the background rate [19]. This infers that the elevated background does not come from the detector and the performance of the N 2 purge in Roseberry and Belmont (noting again that all detectors share a common source of N 2 for the purge) infers that there should not be an issue with the purity of the gas.…”

Section: Jinst 19 P01017mentioning

confidence: 97%

Ultra-low background germanium assay at the Boulby Underground Laboratory

Scovell,

Meehan,

Paling

et al. 2024

J. Inst.

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As we move to an era where next generation ultra-low background particle physics experiments begin to be designed and constructed, the ability to assay materials with high sensitivity and at speed with a variety of techniques will be key. This paper describes the Mirion Technologies (Canberra) specialty ultra-low background detectors installed and commissioned at the Boulby Underground Laboratory between 2017 and 2021. The low background levels of the detectors combine with low background shielding and a radon-reduced dry nitrogen purge system to give sensitivity approaching the best in the world without the need for intricate shielding solutions. For an optimised sample geometry, run for 100 d, it would be possible to reach close to 10 μBq kg-1 (10-12 g/g) for background radionuclides of interest in neutrinoless double-beta decay.

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Section: Jinst 19 P01017mentioning

confidence: 97%

Ultra-low background germanium assay at the Boulby Underground Laboratory

Scovell,

Meehan,

Paling

et al. 2024

J. Inst.

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Development of ultra-pure gadolinium sulfate for the Super-Kamiokande gadolinium project

Hosokawa

Ikeda

Okada

et al. 2022

Progress of Theoretical and Experimental Physics

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This paper reports the development and detailed properties of about 13 tons of gadolinium sulfate octahydrate, $\rm Gd_2(\rm SO_4)_3\cdot \rm 8H_2O$, which has been dissolved into Super-Kamiokande (SK) in the summer of 2020. We evaluate the impact of radioactive impurities in $\rm Gd_2(\rm SO_4)_3\cdot \rm 8H_2O$ on DSNB searches and solar neutrino observation and confirm the need to reduce radioactive and fluorescent impurities by about three orders of magnitude from commercially available high-purity $\rm Gd_2(\rm SO_4)_3\cdot \rm 8H_2O$. In order to produce ultra-high-purity $\rm Gd_2(\rm SO_4)_3\cdot \rm 8H_2O$, we have developed a method to remove impurities from gadolinium oxide, Gd2O3, consisting of acid dissolution, solvent extraction, and pH control processes, followed by a high-purity sulfation process. All of the produced ultra-high-purity $\rm Gd_2(\rm SO_4)_3\cdot \rm 8H_2O$ is assayed by ICP-MS and HPGe detectors to evaluate its quality. Because of the long measurement time of HPGe detectors, we have employed several underground laboratories for making parallel measurements including LSC in Spain, Boulby in the UK, and Kamioka in Japan. In the first half of production, the measured batch purities were found to be consistent with the specifications. However, in the latter half, the $\rm Gd_2(\rm SO_4)_3\cdot \rm 8H_2O$ contained one order of magnitude more 228Ra than the budgeted mean contamination. This was correlated with the corresponding characteristics of the raw material Gd2O3, in which an intrinsically large contamination was present. Based on their modest impact on SK physics, they were nevertheless introduced into the detector. To reduce 228Ra for the next stage of Gd loading to SK, a new process has been successfully established.

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Radioassay of the materials for AMoRE-II experiment

Agrawal,

Alenkov,

Aryal

et al. 2024

Front. Phys.

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The AMoRE-II experiment will search for the 0νββ decay of 100Mo nuclei using molybdate crystal scintillators, operating at milli-Kelvin (mK) temperatures, with a total of 80 kg of 100Mo. The background goal for the experiment is 10–4 counts/keV/kg/year in the region of interest around the 0νββ decay Q-value of 3,034 keV. To achieve this level, the rate of background signals arising from emissions produced by decays of radioactive impurities in the detector and shielding materials must be strictly controlled. To do this, concentrations of such impurities are measured and are controlled through materials selection and purification. In this paper, we describe the design and the construction materials used to build the AMoRE-II detector and shielding system, including active and passive shielding, the cryostat, and the detector holders and instrumentation, and we report on measurements of radioactive impurities within candidate and selected materials.

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Background shielding by dense samples in low-level gamma spectrometry

Cited by 4 publications

References 16 publications

Ultra-low background germanium assay at the Boulby Underground Laboratory

Ultra-low background germanium assay at the Boulby Underground Laboratory

Development of ultra-pure gadolinium sulfate for the Super-Kamiokande gadolinium project

Radioassay of the materials for AMoRE-II experiment

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