Modeling backgrounds for the Majorana Demonstrator

C. R. Haufe; I. J. Arnquist; F. T. Avignone; A. S. Barabash; C. J. Barton; K. H. Bhimani; E. Blalock; B. Bos; M. Busch; M. Buuck; T. S. Caldwell; Y. D. Chan; C. D. Christofferson; P. H. Chu; M. L. Clark; C. Cuesta; J. A. Detwiler; Yu Efremenko; H. Ejiri; S. R. Elliott; G. K. Giovanetti; M. P. Green; J. Gruszko; I. S. Guinn; V. E. Guiseppe; R. Henning; D. Hervas Aguilar; E. W. Hoppe; A. Hostiuc; M. F. Kidd; I. Kim; R. T. Kouzes; T. E. Lannen V; A. Li; A. M. Lopez; J. M. López-Castaño; E. L. Martin; R. D. Martin; R. Massarczyk; S. J. Meijer; T. K. Oli; G. Othman; L. S. Paudel; W. Pettus; A. W.P. Poon; D. C. Radford; A. L. Reine; K. Rielage; N. W. Ruof; D. C. Schaper; D. Tedeschi; R. L. Varner; S. Vasilyev; J. F. Wilkerson; C. Wiseman; W. Xu; C. H. Yu; B. X. Zhu

doi:10.1063/5.0161379

Modeling backgrounds for the Majorana Demonstrator

C. R. Haufe, I. J. Arnquist, F. T. Avignone, A. S. Barabash, C. J. Barton, K. H. Bhimani, E. Blalock, B. Bos, M. Busch, M. Buuck, T. S. Caldwell, Y. D. Chan, C. D. Christofferson, P. H. Chu, M. L. Clark, C. Cuesta, J. A. Detwiler, Yu Efremenko, H. Ejiri, S. R. ElliottG. K. Giovanetti, M. P. Green, J. Gruszko, I. S. Guinn, V. E. Guiseppe, R. Henning, D. Hervas Aguilar, E. W. Hoppe, A. Hostiuc, M. F. Kidd, I. Kim, R. T. Kouzes, T. E. Lannen V, A. Li, A. M. Lopez, J. M. López-Castaño, E. L. Martin, R. D. Martin, R. Massarczyk, S. J. Meijer, T. K. Oli, G. Othman, L. S. Paudel, W. Pettus, A. W.P. Poon, D. C. Radford, A. L. Reine, K. Rielage, N. W. Ruof, D. C. Schaper, D. Tedeschi, R. L. Varner, S. Vasilyev, J. F. Wilkerson, C. Wiseman, W. Xu, C. H. Yu, B. X. Zhu

Research output: Contribution to journal › Conference article › peer-review

Abstract

The MAJORANA DEMONSTRATOR is a neutrinoless double-beta decay (0νββ) experiment containing ~30 kg of p-type point-contact germanium detectors enriched to 88% in 76Ge and ~14 kg of natural germanium detectors. The detectors are housed in two electroformed copper cryostats and surrounded by a graded passive shield with an active muon veto. An extensive radioassay campaign was performed prior to installation to insure the use of ultra-clean materials. The DEMONSTRATOR achieved one of the lowest background rates in the region of the 0νββ Q-value, 15.7±1.4 cts/(FWHM t y) from the low-background configuration spanning most of the 64.5 kg-yr active exposure. Nevertheless this background rate is a factor of five higher than the projected background rate. This discrepancy arises from an excess of events from the 232Th decay chain. Background-model fits aim to explain the deviation from assay-based projections, potentially determine the source(s) of observed backgrounds, and allow a precise measurement of the two-neutrino double-beta decay half-life. The fits agree with earlier simulation studies, which indicate the origin of the 232Th excess is not from a near-detector component and have informed design decisions for the next-generation LEGEND experiment. Recent findings have narrowed the suspected locations for the excess activity, motivating a final simulation and assay campaign to complete the background model.

Original language	English
Article number	100001
Journal	AIP Conference Proceedings
Volume	2908
Issue number	1
DOIs	https://doi.org/10.1063/5.0161379
State	Published - Sep 5 2023
Event	8th International Workshop on Low Radioactivity Techniques, LRT 2022 - Rapid City, United States Duration: Jun 14 2022 → Jun 17 2022

Funding

This material is supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, the Particle Astrophysics and Nuclear Physics Programs of the National Science Foundation, and the Sanford Underground Research Facility.

Funders	Funder number
Sanford Underground Research Facility
National Science Foundation
U.S. Department of Energy
Office of Science
Nuclear Physics

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Haufe, C. R., Arnquist, I. J., Avignone, F. T., Barabash, A. S., Barton, C. J., Bhimani, K. H., Blalock, E., Bos, B., Busch, M., Buuck, M., Caldwell, T. S., Chan, Y. D., Christofferson, C. D., Chu, P. H., Clark, M. L., Cuesta, C., Detwiler, J. A., Efremenko, Y., Ejiri, H., ... Zhu, B. X. (2023). Modeling backgrounds for the Majorana Demonstrator. AIP Conference Proceedings, 2908(1), Article 100001. https://doi.org/10.1063/5.0161379

@article{8c88272c77854940bf230d6042d9f019,

title = "Modeling backgrounds for the Majorana Demonstrator",

abstract = "The MAJORANA DEMONSTRATOR is a neutrinoless double-beta decay (0νββ) experiment containing ~30 kg of p-type point-contact germanium detectors enriched to 88% in 76Ge and ~14 kg of natural germanium detectors. The detectors are housed in two electroformed copper cryostats and surrounded by a graded passive shield with an active muon veto. An extensive radioassay campaign was performed prior to installation to insure the use of ultra-clean materials. The DEMONSTRATOR achieved one of the lowest background rates in the region of the 0νββ Q-value, 15.7±1.4 cts/(FWHM t y) from the low-background configuration spanning most of the 64.5 kg-yr active exposure. Nevertheless this background rate is a factor of five higher than the projected background rate. This discrepancy arises from an excess of events from the 232Th decay chain. Background-model fits aim to explain the deviation from assay-based projections, potentially determine the source(s) of observed backgrounds, and allow a precise measurement of the two-neutrino double-beta decay half-life. The fits agree with earlier simulation studies, which indicate the origin of the 232Th excess is not from a near-detector component and have informed design decisions for the next-generation LEGEND experiment. Recent findings have narrowed the suspected locations for the excess activity, motivating a final simulation and assay campaign to complete the background model.",

author = "Haufe, {C. R.} and Arnquist, {I. J.} and Avignone, {F. T.} and Barabash, {A. S.} and Barton, {C. J.} and Bhimani, {K. H.} and E. Blalock and B. Bos and M. Busch and M. Buuck and Caldwell, {T. S.} and Chan, {Y. D.} and Christofferson, {C. D.} and Chu, {P. H.} and Clark, {M. L.} and C. Cuesta and Detwiler, {J. A.} and Yu Efremenko and H. Ejiri and Elliott, {S. R.} and Giovanetti, {G. K.} and Green, {M. P.} and J. Gruszko and Guinn, {I. S.} and Guiseppe, {V. E.} and R. Henning and Aguilar, {D. Hervas} and Hoppe, {E. W.} and A. Hostiuc and Kidd, {M. F.} and I. Kim and Kouzes, {R. T.} and {Lannen V}, {T. E.} and A. Li and Lopez, {A. M.} and L{\'o}pez-Casta{\~n}o, {J. M.} and Martin, {E. L.} and Martin, {R. D.} and R. Massarczyk and Meijer, {S. J.} and Oli, {T. K.} and G. Othman and Paudel, {L. S.} and W. Pettus and Poon, {A. W.P.} and Radford, {D. C.} and Reine, {A. L.} and K. Rielage and Ruof, {N. W.} and Schaper, {D. C.} and D. Tedeschi and Varner, {R. L.} and S. Vasilyev and Wilkerson, {J. F.} and C. Wiseman and W. Xu and Yu, {C. H.} and Zhu, {B. X.}",

note = "Publisher Copyright: {\textcopyright} 2023 Author(s).; 8th International Workshop on Low Radioactivity Techniques, LRT 2022 ; Conference date: 14-06-2022 Through 17-06-2022",

year = "2023",

month = sep,

day = "5",

doi = "10.1063/5.0161379",

language = "English",

volume = "2908",

journal = "AIP Conference Proceedings",

issn = "0094-243X",

publisher = "American Institute of Physics",

number = "1",

}

Haufe, CR, Arnquist, IJ, Avignone, FT, Barabash, AS, Barton, CJ, Bhimani, KH, Blalock, E, Bos, B, Busch, M, Buuck, M, Caldwell, TS, Chan, YD, Christofferson, CD, Chu, PH, Clark, ML, Cuesta, C, Detwiler, JA, Efremenko, Y, Ejiri, H, Elliott, SR, Giovanetti, GK, Green, MP, Gruszko, J, Guinn, IS, Guiseppe, VE, Henning, R, Aguilar, DH, Hoppe, EW, Hostiuc, A, Kidd, MF, Kim, I, Kouzes, RT, Lannen V, TE, Li, A, Lopez, AM, López-Castaño, JM, Martin, EL, Martin, RD, Massarczyk, R, Meijer, SJ, Oli, TK, Othman, G, Paudel, LS, Pettus, W, Poon, AWP, Radford, DC, Reine, AL, Rielage, K, Ruof, NW, Schaper, DC, Tedeschi, D, Varner, RL, Vasilyev, S, Wilkerson, JF, Wiseman, C, Xu, W, Yu, CH & Zhu, BX 2023, 'Modeling backgrounds for the Majorana Demonstrator', AIP Conference Proceedings, vol. 2908, no. 1, 100001. https://doi.org/10.1063/5.0161379

TY - JOUR

T1 - Modeling backgrounds for the Majorana Demonstrator

AU - Haufe, C. R.

AU - Arnquist, I. J.

AU - Avignone, F. T.

AU - Barabash, A. S.

AU - Barton, C. J.

AU - Bhimani, K. H.

AU - Blalock, E.

AU - Bos, B.

AU - Busch, M.

AU - Buuck, M.

AU - Caldwell, T. S.

AU - Chan, Y. D.

AU - Christofferson, C. D.

AU - Chu, P. H.

AU - Clark, M. L.

AU - Cuesta, C.

AU - Detwiler, J. A.

AU - Efremenko, Yu

AU - Ejiri, H.

AU - Elliott, S. R.

AU - Giovanetti, G. K.

AU - Green, M. P.

AU - Gruszko, J.

AU - Guinn, I. S.

AU - Guiseppe, V. E.

AU - Henning, R.

AU - Aguilar, D. Hervas

AU - Hoppe, E. W.

AU - Hostiuc, A.

AU - Kidd, M. F.

AU - Kim, I.

AU - Kouzes, R. T.

AU - Lannen V, T. E.

AU - Li, A.

AU - Lopez, A. M.

AU - López-Castaño, J. M.

AU - Martin, E. L.

AU - Martin, R. D.

AU - Massarczyk, R.

AU - Meijer, S. J.

AU - Oli, T. K.

AU - Othman, G.

AU - Paudel, L. S.

AU - Pettus, W.

AU - Poon, A. W.P.

AU - Radford, D. C.

AU - Reine, A. L.

AU - Rielage, K.

AU - Ruof, N. W.

AU - Schaper, D. C.

AU - Tedeschi, D.

AU - Varner, R. L.

AU - Vasilyev, S.

AU - Wilkerson, J. F.

AU - Wiseman, C.

AU - Xu, W.

AU - Yu, C. H.

AU - Zhu, B. X.

PY - 2023/9/5

Y1 - 2023/9/5

N2 - The MAJORANA DEMONSTRATOR is a neutrinoless double-beta decay (0νββ) experiment containing ~30 kg of p-type point-contact germanium detectors enriched to 88% in 76Ge and ~14 kg of natural germanium detectors. The detectors are housed in two electroformed copper cryostats and surrounded by a graded passive shield with an active muon veto. An extensive radioassay campaign was performed prior to installation to insure the use of ultra-clean materials. The DEMONSTRATOR achieved one of the lowest background rates in the region of the 0νββ Q-value, 15.7±1.4 cts/(FWHM t y) from the low-background configuration spanning most of the 64.5 kg-yr active exposure. Nevertheless this background rate is a factor of five higher than the projected background rate. This discrepancy arises from an excess of events from the 232Th decay chain. Background-model fits aim to explain the deviation from assay-based projections, potentially determine the source(s) of observed backgrounds, and allow a precise measurement of the two-neutrino double-beta decay half-life. The fits agree with earlier simulation studies, which indicate the origin of the 232Th excess is not from a near-detector component and have informed design decisions for the next-generation LEGEND experiment. Recent findings have narrowed the suspected locations for the excess activity, motivating a final simulation and assay campaign to complete the background model.

AB - The MAJORANA DEMONSTRATOR is a neutrinoless double-beta decay (0νββ) experiment containing ~30 kg of p-type point-contact germanium detectors enriched to 88% in 76Ge and ~14 kg of natural germanium detectors. The detectors are housed in two electroformed copper cryostats and surrounded by a graded passive shield with an active muon veto. An extensive radioassay campaign was performed prior to installation to insure the use of ultra-clean materials. The DEMONSTRATOR achieved one of the lowest background rates in the region of the 0νββ Q-value, 15.7±1.4 cts/(FWHM t y) from the low-background configuration spanning most of the 64.5 kg-yr active exposure. Nevertheless this background rate is a factor of five higher than the projected background rate. This discrepancy arises from an excess of events from the 232Th decay chain. Background-model fits aim to explain the deviation from assay-based projections, potentially determine the source(s) of observed backgrounds, and allow a precise measurement of the two-neutrino double-beta decay half-life. The fits agree with earlier simulation studies, which indicate the origin of the 232Th excess is not from a near-detector component and have informed design decisions for the next-generation LEGEND experiment. Recent findings have narrowed the suspected locations for the excess activity, motivating a final simulation and assay campaign to complete the background model.

UR - http://www.scopus.com/inward/record.url?scp=85177035072&partnerID=8YFLogxK

U2 - 10.1063/5.0161379

DO - 10.1063/5.0161379

M3 - Conference article

AN - SCOPUS:85177035072

SN - 0094-243X

VL - 2908

JO - AIP Conference Proceedings

JF - AIP Conference Proceedings

IS - 1

M1 - 100001

T2 - 8th International Workshop on Low Radioactivity Techniques, LRT 2022

Y2 - 14 June 2022 through 17 June 2022

ER -

Modeling backgrounds for the Majorana Demonstrator

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