TY - JOUR
T1 - Development of low radioactivity photomultiplier tubes for the XMASS-I detector
AU - for XMASS Collaboration, xmass.publications8@km.icrr.u-tokyo.ac.jp
AU - Abe, K.
AU - Hiraide, K.
AU - Ichimura, K.
AU - Kishimoto, Y.
AU - Kobayashi, K.
AU - Kobayashi, M.
AU - Moriyama, S.
AU - Nakahata, M.
AU - Norita, T.
AU - Ogawa, H.
AU - Sato, K.
AU - Sekiya, H.
AU - Takachio, O.
AU - Takeda, A.
AU - Tasaka, S.
AU - Yamashita, M.
AU - Yang, B. S.
AU - Kim, N. Y.
AU - Kim, Y. D.
AU - Itow, Y.
AU - Kanzawa, K.
AU - Kegasa, R.
AU - Masuda, K.
AU - Takiya, H.
AU - Fushimi, K.
AU - Kanzaki, G.
AU - Martens, K.
AU - Suzuki, Y.
AU - Xu, B. D.
AU - Fujita, R.
AU - Hosokawa, K.
AU - Miuchi, K.
AU - Oka, N.
AU - Takeuchi, Y.
AU - Kim, Y. H.
AU - Lee, K. B.
AU - Lee, M. K.
AU - Fukuda, Y.
AU - Miyasaka, M.
AU - Nishijima, K.
AU - Nakamura, S.
N1 - Funding Information:
We thank Hamamatsu Photonics K. K. for the cooperation in producing the low RI PMTs. We gratefully acknowledge the cooperation of Kamioka Mining and Smelting Company. This work was supported by the Japanese Ministry of Education, Culture, Sports, Science and Technology , Grant-in-Aid for Scientific Research, ICRR Joint-Usage, JSPS KAKENHI Grant Number, 19GS0204 and 26104004 , and partially by the National Research Foundation of Korea Grant ( NRF-2011-220-C00006 ) and Institute for Basic Science ( IBS-R017-G1-2018-a00 ).
Publisher Copyright:
© 2019 Elsevier B.V.
PY - 2019/4/1
Y1 - 2019/4/1
N2 - XMASS-I is a single-phase liquid xenon detector whose purpose is direct detection of dark matter. To achieve the low background requirements necessary in the detector, a new model of photomultiplier tubes (PMTs), R10789, with a hexagonal window was developed based on the R8778 PMT used in the XMASS prototype detector. We screened the numerous component materials for their radioactivity. During development, the largest contributions to the reduction of radioactivity came from the stem and the dynode support. The glass stem was exchanged to the Kovar alloy one and the ceramic support were changed to the quartz one. R10789 is the first model of Hamamatsu Photonics K. K. that adopted these materials for low background purposes and provided a groundbreaking step for further reductions of radioactivity in PMTs. Measurements with germanium detectors showed 1.2 ± 0.3 mBq/PMT of 226 Ra, less than 0.78 mBq/PMT of 228 Ra, 9.1 ± 2.2 mBq/PMT of 40 K, and 2.8 ± 0.2 mBq/PMT of 60 Co. In this paper, the radioactive details of the developed R10789 are described together with our screening methods and the components of the PMT.
AB - XMASS-I is a single-phase liquid xenon detector whose purpose is direct detection of dark matter. To achieve the low background requirements necessary in the detector, a new model of photomultiplier tubes (PMTs), R10789, with a hexagonal window was developed based on the R8778 PMT used in the XMASS prototype detector. We screened the numerous component materials for their radioactivity. During development, the largest contributions to the reduction of radioactivity came from the stem and the dynode support. The glass stem was exchanged to the Kovar alloy one and the ceramic support were changed to the quartz one. R10789 is the first model of Hamamatsu Photonics K. K. that adopted these materials for low background purposes and provided a groundbreaking step for further reductions of radioactivity in PMTs. Measurements with germanium detectors showed 1.2 ± 0.3 mBq/PMT of 226 Ra, less than 0.78 mBq/PMT of 228 Ra, 9.1 ± 2.2 mBq/PMT of 40 K, and 2.8 ± 0.2 mBq/PMT of 60 Co. In this paper, the radioactive details of the developed R10789 are described together with our screening methods and the components of the PMT.
KW - HPGe
KW - Mass spectrometry
KW - PMT
KW - Radioactivity
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U2 - 10.1016/j.nima.2018.12.083
DO - 10.1016/j.nima.2018.12.083
M3 - Article
AN - SCOPUS:85059804786
SN - 0168-9002
VL - 922
SP - 171
EP - 176
JO - Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
JF - Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
ER -