Radioassay of the materials for AMoRE-II experiment Provisionally Accepted

A. Agrawal¹ V V. Alenkov² P Aryal³ H Bae⁴ J Beyer⁵ B Bhandari⁶ R S. Boiko⁷ K Boonin⁸ O Buzanov² C R. Byeon⁹ N Chanthima⁸ M K. Cheoun¹⁰ Junseok Choe⁹ S Choi¹¹ S Choudhury¹ J S. Chung¹² Fedor Danevich⁷ M Djamal¹³ D Drung⁵ C Enss¹⁴ A Fleischmann¹⁴ A M. Gangapshev¹⁵ Loredana Gastaldo¹⁴ Y M. Gavrilyuk¹⁵ A M. Gezhaev⁷ Olga Gileva^9* V D. Grigorieva¹⁶ V I. Gurentsov⁷ C Ha¹² D H. Ha³ E J. Ha¹⁰ D H. Hwang⁹ E J. Jeon^{9, 17} J A. Jeon⁹ H S. Jo³ Jakrapong Kaewkhao⁸ C S. Kang⁹ W G. Kang⁹ Vladimir V. Kazalov¹⁵ S Kempf¹⁴ Arshad Khan³ S Khan¹⁸ D Y. Kim⁹ G W. Kim⁹ H B. Kim¹⁹ Ho-jong Kim⁹ Hong J. Kim³ Hyelim Kim⁹ Hyunsoo Kim⁶ M B. Kim⁹ S C. Kim⁹ Sun Kee Kim¹⁹ Sora Kim²⁰ W T. Kim⁹ Y D. Kim⁹ Yong-Hamb Kim⁹ K Kirdsiri⁸ Y J. Ko⁹ V V. Kobychev²¹ V Kornoukhov²² V V. Kuzminov⁷ D H. Kwon¹⁷ C H. Lee⁹ D Y. Lee⁹ Eunkyung LEE^9* H J. Lee⁹ Hyun Su Lee^{9, 17} Jaison Lee⁹ J Y. Lee³ Kyoung Beom Lee²³ Moo Hyun Lee^{9, 17} Minkyu Lee²³ S W. Lee⁹ Y C. Lee²⁴ D S. Leonard^9* H S. Lim³ B Mailyan²⁵ E P. Makarov¹⁶ P Nyanda¹⁷ Y Oh⁹ S L. Olsen⁹ S I. Panasenko²⁶ Hyangkyu Park²⁷ Hyeonseo Park²³ K S. Park⁹ S Y. Park⁹ O G. Polischuk²¹ H Prihtiadi²⁸ S Ra⁹ S S. Ratkevich²⁶ G Rooh²⁹ M B. Sari³⁰ J Seo⁹ Kyungmin Seo⁶ B Sharma¹⁷ K A. Shin⁹ V N. Shlegel¹⁶ K Siyeon¹² J So⁹ Nazar V. Sokur²¹ J K. Son⁹ J W. Song³ N Srisittipokakun⁸ V I. Tretyak²¹ R Wirawan³¹ K R. Woo⁹ H J. Yeon⁹ Young Soo Yoon²³ Q Yue³²

• ¹Indian Institute of Science (IISc), India
• ²Fomos material, Russia
• ³Kyungpook National University, Republic of Korea
• ⁴The University of Tokyo, Japan
• ⁵Physical-Technical Federal Institute, Germany
• ⁶Sejong University, Republic of Korea
• ⁷Institute for Nuclear Research (RAS), Russia
• ⁸Nakhon Pathom Rajabhat University, Thailand
• ⁹Center for Underground Physics, Institute for Basic Science, Republic of Korea
• ¹⁰Soongsil University, Republic of Korea
• ¹¹Shiv Nadar University, India
• ¹²Chung-Ang University, Republic of Korea
• ¹³Bandung Institute of Technology, Indonesia
• ¹⁴Kirchhoff-Institute for Physics, Department of Physics and Astronomy, Heidelberg University, Germany
• ¹⁵Baksan Neutrino Observatory, Institute for Nuclear Research (RAS), Russia
• ¹⁶Nikolaev Institute of Inorganic Chemistry (RAS), Russia
• ¹⁷University of Science & Technology, Republic of Korea
• ¹⁸Kohat University of Science and Technology, Pakistan
• ¹⁹Seoul National University, Republic of Korea
• ²⁰Ajou University, Republic of Korea
• ²¹Institute for Nuclear Research, National Academy of Sciences of Ukraine (NAN Ukraine), Ukraine
• ²²National Research Nuclear University MEPhI, Russia
• ²³Korea Research Institute of Standards and Science, Republic of Korea
• ²⁴Seoul National University Hospital, Republic of Korea
• ²⁵Florida Institute of Technology, United States
• ²⁶V. N. Karazin Kharkiv National University, Ukraine
• ²⁷Korea University, Republic of Korea
• ²⁸State University of Malang, Indonesia
• ²⁹Abdul Wali Khan University Mardan, Pakistan
• ³⁰Padang State University, Indonesia
• ³¹University of Mataram, Indonesia
• ³²Tsinghua University, China

The AMoRE-II experiment will search for the 0νββ decay of 100 Mo nuclei using molybdate crystal scintillators, operating at milli-Kelvin (mK) temperatures, with a total of 80 kg of 100 Mo. 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 3034 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 1 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.