Second gadolinium loading to Super-Kamiokande

The Super-Kamiokande Collaboration

doi:10.1016/j.nima.2024.169480

Second gadolinium loading to Super-Kamiokande

The Super-Kamiokande Collaboration

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Abstract

The first loading of gadolinium (Gd) into Super-Kamiokande in 2020 was successful, and the neutron capture efficiency on Gd reached 50%. To further increase the Gd neutron capture efficiency to 75%, 26.1 tons of Gd₂(SO₄)₃⋅8H₂O was additionally loaded into Super-Kamiokande (SK) from May 31 to July 4, 2022. As the amount of loaded Gd₂(SO₄)₃⋅8H₂O was doubled compared to the first loading, the capacity of the powder dissolving system was doubled. We also developed new batches of gadolinium sulfate with even further reduced radioactive impurities. In addition, a more efficient screening method was devised and implemented to evaluate these new batches of Gd₂(SO₄)₃⋅8H₂O. Following the second loading, the Gd concentration in SK was measured to be 333.5±2.5 ppm via an Atomic Absorption Spectrometer (AAS). From the mean neutron capture time constant of neutrons from an Am/Be calibration source, the Gd concentration was independently measured to be 332.7 ± 6.8(sys.) ± 1.1(stat.) ppm, consistent with the AAS result. Furthermore, during the loading the Gd concentration was monitored continually using the capture time constant of each spallation neutron produced by cosmic-ray muons, and the final neutron capture efficiency was shown to become 1.5 times higher than that of the first loaded phase, as expected.

Original language	English
Article number	169480
Journal	Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Volume	1065
Early online date	8 Jul 2024
DOIs	https://doi.org/10.1016/j.nima.2024.169480
Publication status	Published - Aug 2024

Keywords

Gadolinium
Neutrino
Neutron
Water Cherenkov detector

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10.1016/j.nima.2024.169480

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@article{d1debeb8b9484146b2f1a2819faf10da,

title = "Second gadolinium loading to Super-Kamiokande",

abstract = "The first loading of gadolinium (Gd) into Super-Kamiokande in 2020 was successful, and the neutron capture efficiency on Gd reached 50%. To further increase the Gd neutron capture efficiency to 75%, 26.1 tons of Gd2(SO4)3⋅8H2O was additionally loaded into Super-Kamiokande (SK) from May 31 to July 4, 2022. As the amount of loaded Gd2(SO4)3⋅8H2O was doubled compared to the first loading, the capacity of the powder dissolving system was doubled. We also developed new batches of gadolinium sulfate with even further reduced radioactive impurities. In addition, a more efficient screening method was devised and implemented to evaluate these new batches of Gd2(SO4)3⋅8H2O. Following the second loading, the Gd concentration in SK was measured to be 333.5±2.5 ppm via an Atomic Absorption Spectrometer (AAS). From the mean neutron capture time constant of neutrons from an Am/Be calibration source, the Gd concentration was independently measured to be 332.7 ± 6.8(sys.) ± 1.1(stat.) ppm, consistent with the AAS result. Furthermore, during the loading the Gd concentration was monitored continually using the capture time constant of each spallation neutron produced by cosmic-ray muons, and the final neutron capture efficiency was shown to become 1.5 times higher than that of the first loaded phase, as expected.",

keywords = "Gadolinium, Neutrino, Neutron, Water Cherenkov detector",

author = "{The Super-Kamiokande Collaboration} and K. Abe and C. Bronner and Y. Hayato and K. Hiraide and K. Hosokawa and K. Ieki and M. Ikeda and J. Kameda and Y. Kanemura and R. Kaneshima and Y. Kashiwagi and Y. Kataoka and S. Miki and S. Mine and M. Miura and S. Moriyama and Y. Nakano and M. Nakahata and S. Nakayama and Y. Noguchi and K. Sato and H. Sekiya and H. Shiba and K. Shimizu and M. Shiozawa and Y. Sonoda and Y. Suzuki and A. Takeda and Y. Takemoto and H. Tanaka and T. Yano and S. Han and T. Kajita and K. Okumura and T. Tashiro and T. Tomiya and X. Wang and S. Yoshida and P. Fernandez and L. Labarga and N. Bhuiyan and Burton, {G. T.} and {Di Lodovico}, F. and J. Gao and A. Goldsack and T. Katori and J. Migenda and Ramsden, {R. M.} and Z. Xie and S. Zsoldos",

note = "Publisher Copyright: {\textcopyright} 2024 The Author(s)",

year = "2024",

month = aug,

doi = "10.1016/j.nima.2024.169480",

language = "English",

volume = "1065",

journal = "Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment",

issn = "0168-9002",

publisher = "Elsevier",

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TY - JOUR

T1 - Second gadolinium loading to Super-Kamiokande

AU - The Super-Kamiokande Collaboration

AU - Abe, K.

AU - Bronner, C.

AU - Hayato, Y.

AU - Hiraide, K.

AU - Hosokawa, K.

AU - Ieki, K.

AU - Ikeda, M.

AU - Kameda, J.

AU - Kanemura, Y.

AU - Kaneshima, R.

AU - Kashiwagi, Y.

AU - Kataoka, Y.

AU - Miki, S.

AU - Mine, S.

AU - Miura, M.

AU - Moriyama, S.

AU - Nakano, Y.

AU - Nakahata, M.

AU - Nakayama, S.

AU - Noguchi, Y.

AU - Sato, K.

AU - Sekiya, H.

AU - Shiba, H.

AU - Shimizu, K.

AU - Shiozawa, M.

AU - Sonoda, Y.

AU - Suzuki, Y.

AU - Takeda, A.

AU - Takemoto, Y.

AU - Tanaka, H.

AU - Yano, T.

AU - Han, S.

AU - Kajita, T.

AU - Okumura, K.

AU - Tashiro, T.

AU - Tomiya, T.

AU - Wang, X.

AU - Yoshida, S.

AU - Fernandez, P.

AU - Labarga, L.

AU - Bhuiyan, N.

AU - Burton, G. T.

AU - Di Lodovico, F.

AU - Gao, J.

AU - Goldsack, A.

AU - Katori, T.

AU - Migenda, J.

AU - Ramsden, R. M.

AU - Xie, Z.

AU - Zsoldos, S.

PY - 2024/8

Y1 - 2024/8

N2 - The first loading of gadolinium (Gd) into Super-Kamiokande in 2020 was successful, and the neutron capture efficiency on Gd reached 50%. To further increase the Gd neutron capture efficiency to 75%, 26.1 tons of Gd2(SO4)3⋅8H2O was additionally loaded into Super-Kamiokande (SK) from May 31 to July 4, 2022. As the amount of loaded Gd2(SO4)3⋅8H2O was doubled compared to the first loading, the capacity of the powder dissolving system was doubled. We also developed new batches of gadolinium sulfate with even further reduced radioactive impurities. In addition, a more efficient screening method was devised and implemented to evaluate these new batches of Gd2(SO4)3⋅8H2O. Following the second loading, the Gd concentration in SK was measured to be 333.5±2.5 ppm via an Atomic Absorption Spectrometer (AAS). From the mean neutron capture time constant of neutrons from an Am/Be calibration source, the Gd concentration was independently measured to be 332.7 ± 6.8(sys.) ± 1.1(stat.) ppm, consistent with the AAS result. Furthermore, during the loading the Gd concentration was monitored continually using the capture time constant of each spallation neutron produced by cosmic-ray muons, and the final neutron capture efficiency was shown to become 1.5 times higher than that of the first loaded phase, as expected.

AB - The first loading of gadolinium (Gd) into Super-Kamiokande in 2020 was successful, and the neutron capture efficiency on Gd reached 50%. To further increase the Gd neutron capture efficiency to 75%, 26.1 tons of Gd2(SO4)3⋅8H2O was additionally loaded into Super-Kamiokande (SK) from May 31 to July 4, 2022. As the amount of loaded Gd2(SO4)3⋅8H2O was doubled compared to the first loading, the capacity of the powder dissolving system was doubled. We also developed new batches of gadolinium sulfate with even further reduced radioactive impurities. In addition, a more efficient screening method was devised and implemented to evaluate these new batches of Gd2(SO4)3⋅8H2O. Following the second loading, the Gd concentration in SK was measured to be 333.5±2.5 ppm via an Atomic Absorption Spectrometer (AAS). From the mean neutron capture time constant of neutrons from an Am/Be calibration source, the Gd concentration was independently measured to be 332.7 ± 6.8(sys.) ± 1.1(stat.) ppm, consistent with the AAS result. Furthermore, during the loading the Gd concentration was monitored continually using the capture time constant of each spallation neutron produced by cosmic-ray muons, and the final neutron capture efficiency was shown to become 1.5 times higher than that of the first loaded phase, as expected.

KW - Gadolinium

KW - Neutrino

KW - Neutron

KW - Water Cherenkov detector

UR - http://www.scopus.com/inward/record.url?scp=85195264361&partnerID=8YFLogxK

U2 - 10.1016/j.nima.2024.169480

DO - 10.1016/j.nima.2024.169480

M3 - Article

AN - SCOPUS:85195264361

SN - 0168-9002

VL - 1065

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

M1 - 169480

ER -

Second gadolinium loading to Super-Kamiokande

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Keywords

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