Measurement of the 85Kr specific activity in the GERDA liquid argon

M. Agostini; A. Alexander; G. Araujo; A. M. Bakalyarov; M. Balata; I. Barabanov; L. Baudis; C. Bauer; S. Belogurov; A. Bettini; L. Bezrukov; V. Biancacci; E. Bossio; V. Bothe; R. Brugnera; A. Caldwell; S. Calgaro; C. Cattadori; A. Chernogorov; P.-J. Chiu; T. Comellato; V. D’Andrea; E. V. Demidova; N. Di Marco; E. Doroshkevich; M. Fomina; A. Gangapshev; A. Garfagnini; C. Gooch; P. Grabmayr; V. Gurentsov; K. Gusev; J. Hakenmüller; S. Hemmer; W. Hofmann; J. Huang; M. Hult; L. V. Inzhechik; J. Janicskó Csáthy; J. Jochum; M. Junker; V. Kazalov; Y. Kermaïdic; H. Khushbakht; T. Kihm; K. Kilgus; I. V. Kirpichnikov; A. Klimenko; K. T. Knöpfle; O. Kochetov; V. N. Kornoukhov; P. Krause; V. V. Kuzminov; M. Laubenstein; M. Lindner; I. Lippi; A. Lubashevskiy; B. Lubsandorzhiev; G. Lutter; C. Macolino; B. Majorovits; W. Maneschg; G. Marshall; M. Misiaszek; M. Morella; Y. Müller; I. Nemchenok; M. Neuberger; L. Pandola; K. Pelczar; L. Pertoldi; P. Piseri; A. Pullia; C. Ransom; L. Rauscher; M. Redchuk; S. Riboldi; N. Rumyantseva; C. Sada; S. Sailer; F. Salamida; S. Schönert; J. Schreiner; A.-K. Schütz; O. Schulz; M. Schwarz; B. Schwingenheuer; O. Selivanenko; E. Shevchik; M. Shirchenko; L. Shtembari; H. Simgen; A. Smolnikov; D. Stukov; S. Sullivan; A. A. Vasenko; A. Veresnikova; C. Vignoli; K. von Sturm; T. Wester; C. Wiesinger; M. Wojcik; E. Yanovich; B. Zatschler; I. Zhitnikov; S. V. Zhukov; D. Zinatulina; A. Zschocke; K. Zuber; G. Zuze

doi:10.1140/epjc/s10052-025-14135-8

2024 Impact factor 4.8

Particles and Fields

Open Access

Eur. Phys. J. C (2025) 85: 518
https://doi.org/10.1140/epjc/s10052-025-14135-8

Regular Article - Experimental Physics

Measurement of the ⁸⁵Kr specific activity in the GERDA liquid argon

M. Agostini¹⁰, A. Alexander¹⁰, G. Araujo²¹, A. M. Bakalyarov¹⁵, M. Balata¹, I. Barabanov¹³, L. Baudis²¹, C. Bauer⁹, S. Belogurov¹³^,14^,26, A. Bettini¹⁸^,19, L. Bezrukov¹³, V. Biancacci³, E. Bossio¹⁷^,25^,25, V. Bothe⁹, R. Brugnera¹⁸^,19, A. Caldwell¹⁶, S. Calgaro¹⁸^,19, C. Cattadori¹¹, A. Chernogorov¹⁴^,15, P.-J. Chiu²¹, T. Comellato¹⁷, V. D’Andrea³, E. V. Demidova¹⁴, N. Di Marco², E. Doroshkevich¹³, M. Fomina⁷, A. Gangapshev⁹^,13, A. Garfagnini¹⁸^,19, C. Gooch¹⁶, P. Grabmayr²⁰, V. Gurentsov¹³, K. Gusev⁷^,15^,17, J. Hakenmüller⁹^,22^,22, S. Hemmer¹⁹, W. Hofmann⁹, J. Huang²¹, M. Hult⁸, L. V. Inzhechik¹³^,27, J. Janicskó Csáthy¹⁷^,23^,23, J. Jochum²⁰, M. Junker¹, V. Kazalov¹³, Y. Kermaïdic⁹, H. Khushbakht²⁰, T. Kihm⁹, K. Kilgus²⁰, I. V. Kirpichnikov¹⁴, A. Klimenko⁷^,9^,28, K. T. Knöpfle⁹, O. Kochetov⁷, V. N. Kornoukhov¹³^,26, P. Krause¹⁷, V. V. Kuzminov¹³, M. Laubenstein¹, M. Lindner⁹, I. Lippi¹⁹, A. Lubashevskiy⁷, B. Lubsandorzhiev¹³, G. Lutter⁸, C. Macolino³, B. Majorovits¹⁶, W. Maneschg⁹, G. Marshall¹⁰, M. Misiaszek⁵, M. Morella², Y. Müller²¹, I. Nemchenok⁷^,28, M. Neuberger¹⁷, L. Pandola⁴, K. Pelczar⁸, L. Pertoldi¹⁷^,19, P. Piseri¹², A. Pullia¹², C. Ransom²¹, L. Rauscher²⁰, M. Redchuk¹⁹, S. Riboldi¹², N. Rumyantseva⁷^,15, C. Sada¹⁸^,19, S. Sailer⁹, F. Salamida³, S. Schönert¹⁷, J. Schreiner⁹, A.-K. Schütz²⁰^,24^,24, O. Schulz¹⁶, M. Schwarz¹⁷, B. Schwingenheuer⁹, O. Selivanenko¹³, E. Shevchik⁷, M. Shirchenko⁷, L. Shtembari¹⁶, H. Simgen⁹, A. Smolnikov⁷^,9, D. Stukov¹⁵, S. Sullivan⁹, A. A. Vasenko¹⁴, A. Veresnikova¹³, C. Vignoli¹, K. von Sturm¹⁸^,19, T. Wester⁶, C. Wiesinger¹⁷, M. Wojcik⁵, E. Yanovich¹³, B. Zatschler⁶, I. Zhitnikov⁷, S. V. Zhukov¹⁵, D. Zinatulina⁷, A. Zschocke²⁰, K. Zuber⁶, G. Zuze⁵ and GERDA Collaboration*²⁹^a

¹ INFN Laboratori Nazionali del Gran Sasso, Assergi, Italy
² INFN Laboratori Nazionali del Gran Sasso and Gran Sasso Science Institute, Assergi, Italy
³ INFN Laboratori Nazionali del Gran Sasso and Università degli Studi dell’Aquila, L’Aquila, Italy
⁴ INFN Laboratori Nazionali del Sud, Catania, Italy
⁵ Institute of Physics, Jagiellonian University, Kraków, Poland
⁶ Institut für Kern- und Teilchenphysik, Technische Universität Dresden, Dresden, Germany
⁷ Joint Institute for Nuclear Research, Dubna, Russia
⁸ European Commission, JRC-Geel, Geel, Belgium
⁹ Max-Planck-Institut für Kernphysik, Heidelberg, Germany
¹⁰ Department of Physics and Astronomy, University College London, London, UK
¹¹ INFN Milano Bicocca, Milan, Italy
¹² Dipartimento di Fisica, Università degli Studi di Milano and INFN Milano, Milan, Italy
¹³ Institute for Nuclear Research of the Russian Academy of Sciences, Moscow, Russia
¹⁴ Institute for Theoretical and Experimental Physics, NRC “Kurchatov Institute”, Moscow, Russia
¹⁵ National Research Centre “Kurchatov Institute”, Moscow, Russia
¹⁶ Max-Planck-Institut für Physik, Munich, Germany
¹⁷ Physik Department, Technische Universität München, Munich, Germany
¹⁸ Dipartimento di Fisica e Astronomia, Università degli Studi di Padova, Padua, Italy
¹⁹ INFN Padova, Padua, Italy
²⁰ Physikalisches Institut, Eberhard Karls Universität Tübingen, Tübingen, Germany
²¹ Physik-Institut, Universität Zürich, Zurich, Switzerland
²² Duke University, Durham, NC, USA
²³ Semilab Zrt, Budapest, Hungary
²⁴ Nuclear Science Division, Berkeley, USA
²⁵ IRFU, CEA, Université Paris-Saclay, Gif-sur-Yvette, France
²⁶ NRNU MEPhI, Moscow, Russia
²⁷ Moscow Institute of Physics and Technology, Moscow, Russia
²⁸ Dubna State University, Dubna, Russia
²⁹ Max-Planck-Institut für Kernphysik, Heidelberg, Germany

^a gerda-eb@mpi-hd.mpg.de

Received: 27 December 2024
Accepted: 28 March 2025
Published online: 12 May 2025

Abstract

The radioactive isotope ⁸⁵Kr is found in significant quantities in the atmosphere largely due to nuclear industry. Its $β$ ${\upbeta }$ -decay with a half-life of 10.7 years and a Q-value of 687 keV is a dangerous background source for low-threshold noble gas and liquid detectors, which distill their detector medium from air. The Gerda experiment was operating high-purity germanium detectors immersed in a clean liquid argon bath deep underground to search for neutrinoless double beta decay with unprecedented sensitivity. The ⁸⁵Kr specific activity in the liquid argon at the start of the second phase of the experiment has been determined to be $(0.36 \pm 0.03)$ $(0.36 \pm 0.03)$ mBq/kg through an analysis of the full subsequent data set that exploits the excellent $γ$ ${\upgamma }$ -ray spectroscopic capabilities of Gerda.

I. Barabanov: Deceased.

Present address: IRFU, CEA, Université Paris-Saclay, Gif-sur-Yvette, France

Present address: Duke University, Durham, NC, USA

Present address: Semilab Zrt, Budapest, Hungary

Present address: Nuclear Science Division, Berkeley, USA

© The Author(s) 2025

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