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Production and characterization of $^{228}$Th calibration sources with low neutron emission for GERDA


Baudis, L; Benato, G; Carconi, P; Cattadori, C; De Felice, P; Eberhardt, K; Eichler, R; Petrucci, A; Tarka, M; Walter, M (2015). Production and characterization of $^{228}$Th calibration sources with low neutron emission for GERDA. Journal of Instrumentation, 10(12):P12005.

Abstract

The GERDA experiment at the Laboratori Nazionali del Gran Sasso (LNGS) searches for the neutrinoless double beta decay of (76)Ge. In view of the GERDA Phase II data collection, four new (228)Th radioactive sources for the calibration of the germanium detectors enriched in (76)Ge have been produced with a new technique, leading to a reduced neutron emission rate from (α, n) reactions. The gamma activities of the sources were determined with a total uncertainty of ~4% using an ultra-low background HPGe detector operated underground at LNGS. The neutron emission rate was determined using a low background LiI(Eu) detector and a (3)He counter at LNGS. In both cases, the measured neutron activity is ~10(−)(6) n/(s⋅Bq), with a reduction of about one order of magnitude with respect to commercially available (228)Th sources. Additionally, a specific leak test with a sensitivity to leaks down to ~10 mBq was developed to investigate the tightness of the stainless steel capsules housing the sources after their use in cryogenic environment.

Abstract

The GERDA experiment at the Laboratori Nazionali del Gran Sasso (LNGS) searches for the neutrinoless double beta decay of (76)Ge. In view of the GERDA Phase II data collection, four new (228)Th radioactive sources for the calibration of the germanium detectors enriched in (76)Ge have been produced with a new technique, leading to a reduced neutron emission rate from (α, n) reactions. The gamma activities of the sources were determined with a total uncertainty of ~4% using an ultra-low background HPGe detector operated underground at LNGS. The neutron emission rate was determined using a low background LiI(Eu) detector and a (3)He counter at LNGS. In both cases, the measured neutron activity is ~10(−)(6) n/(s⋅Bq), with a reduction of about one order of magnitude with respect to commercially available (228)Th sources. Additionally, a specific leak test with a sensitivity to leaks down to ~10 mBq was developed to investigate the tightness of the stainless steel capsules housing the sources after their use in cryogenic environment.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Physics Institute
Dewey Decimal Classification:530 Physics
Language:English
Date:2015
Deposited On:18 Feb 2016 10:05
Last Modified:14 Feb 2018 11:13
Publisher:IOP Publishing
ISSN:1748-0221
OA Status:Green
Publisher DOI:https://doi.org/10.1088/1748-0221/10/12/P12005
Other Identification Number:arXiv:1508.05731v1

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