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1. Exotic Dark Matter Search with the Majorana Demonstrator

Author

Arnquist, IJ, Avignone, FT, Barabash, AS, Barton, CJ, Bhimani, KH, Blalock, E, Bos, B, Busch, M, Buuck, M, Caldwell, TS, Chan, Y-D, Christofferson, CD, Chu, P-H, Clark, ML, Cuesta, C, Detwiler, JA, Efremenko, Yu, Ejiri, H, Elliott, SR, Giovanetti, GK, Green, MP, Gruszko, J, Guinn, IS, Guiseppe, VE, Haufe, CR, Henning, R, Hervas Aguilar, D, 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, Mertens, S, Oli, TK, Othman, G, Paudel, LS, Pettus, W, Poon, AWP, Radford, DC, Rager, J, Reine, AL, Rielage, K, Ruof, NW, Schaper, DC, Tedeschi, D, Varner, RL, Vasilyev, S, Wilkerson, JF, Wiseman, C, Xu, W, Yu, C-H, and Zhu, BX

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Majorana Collaboration, Mathematical Sciences, Engineering, General Physics, Mathematical sciences, Physical sciences
Abstract

With excellent energy resolution and ultralow-level radiogenic backgrounds, the high-purity germanium detectors in the Majorana Demonstrator enable searches for several classes of exotic dark matter (DM) models. In this work, we report new experimental limits on keV-scale sterile neutrino DM via the transition magnetic moment from conversion to active neutrinos ν_{s}→ν_{a}. We report new limits on fermionic dark matter absorption (χ+A→ν+A) and sub-GeV DM-nucleus 3→2 scattering (χ+χ+A→ϕ+A), and new exclusion limits for bosonic dark matter (axionlike particles and dark photons). These searches utilize the (1-100)-keV low-energy region of a 37.5-kg y exposure collected by the Demonstrator between May 2016 and November 2019 using a set of ^{76}Ge-enriched detectors whose surface exposure time was carefully controlled, resulting in extremely low levels of cosmogenic activation.

Published
2024

2. The Majorana Demonstrator Status and Preliminary Results

Author

Yu C.-H., Alvis S.I., Arnquist I.J., Avignone F.T., Barabash A.S., Barton C.J., Bertrand F.E., Bode T., Brudanin V., Busch M., Buuck M., Caldwell T.S., Chan Y.-D., Christofferson C.D., Chu P.-H., Cuesta C., Detwiler J.A., Dunagan C., Efremenko Yu, Ejiri H., Elliott S.R., Gilliss T., Giovanetti G.K., Green M., Gruszko J., Guinn I.S., Guiseppe V.E., Haufe C.R., Hehn L., Henning R., Hoppe E.W., Howe M.A., Keeter K.J., Kidd M.F., Konovalov S.I., Kouzes R.T., Lopez A.M., Martin R.D., Massarczyk R., Meijer S.J., Mertens S., Myslik J., Othman G., Pettus W., Poon A.W.P., Radford D.C., Rager J., Reine A.L., Rielage K., Ruof N.W., Shanks B., Shirchenko M., Suriano A.M., Tedeschi D., Varner R.L., Vasilyev S., Vetter K., Vorren K., White B.R., Wilkerson J.F., Wiseman C., Xu W., Yakushev E., Yumatov V., Zhitnikov I., and Zhu B.Z.

Subjects
Physics, QC1-999
Abstract

The Majorana Collaboration is using an array of high-purity Ge detectors to search for neutrinoless double-beta decay in 76Ge. Searches for neutrinoless double-beta decay are understood to be the only viable experimental method for testing the Majorana nature of the neutrino. Observation of this decay would imply violation of lepton number, that neutrinos are Majorana in nature, and provide information on the neutrino mass. The Majorana Demonstrator comprises 44.1 kg of p-type point-contact Ge detectors (29.7 kg enriched in 76Ge) surrounded by a low-background shield system. The experiment achieved a high efficiency of converting raw Ge material to detectors and an unprecedented detector energy resolution of 2.5 keV FWHM at Qββ. The Majorana collaboration began taking physics data in 2016. This paper summarizes key construction aspects of the Demonstrator and shows preliminary results from initial data.

Published
2018
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3. The MAJORANA DEMONSTRATOR Readout Electronics System

Author

Abgrall, N., Amman, M., Arnquist, I. J., Avignone III, F. T., Barabash, A. S., Barton, C. J., Barton, P. J., Bertrand, F. E., Bhimani, K. H., Bos, B., Bradley, A. W., Burritt, T. H., Busch, M., Buuck, M., Caldwell, T. S., Chan, Y-D., Christofferson, C. D., Chu, P. -H., Clark, M. L., Cooper, R. J., Cuesta, C., Detwiler, J. A., Drobizhev, A., Edwins, D. W., Efremenko, Yu., Ejiri, H., Elliott, S. R., Gilliss, T., Giovanetti, G. K., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Haufe, C. R., Hegedus, R. J., Henning, R., Aguilar, D. Hervas, Hoppe, E. W., Hostiuc, A., Kidd, M. F., Kim, I., Kouzes, R. T., Li, A., Loach, J. C., Lopez, A. M., López-Castaño, J. M., Luke, P. N., Martin, E. L., Martin, R. D., Massarczyk, R., Meijer, S. J., Mertens, S., Myslik, J., Oli, T. K., Othman, G., Peterson, D., Pettus, W., Poon, A. W. P., Radford, D. C., Rager, J., Reine, A. L., Rielage, K., Robertson, R. G. H., Ruof, N. W., Sayki, B., Stortini, M. J., Tedeschi, D., Turqueti, M., Van Wechel, T. D., Varner, R. L., Vasilyev, S., Vetter, K., Wilkerson, J. F., Wiseman, C., Xu, W., Yaver, H., Yu, C. -H., Zhu, B. X., and Zimmermann, S.

Subjects
Physics - Instrumentation and Detectors, High Energy Physics - Experiment, Nuclear Experiment
Abstract

The MAJORANA DEMONSTRATOR comprises two arrays of high-purity germanium detectors constructed to search for neutrinoless double-beta decay in 76-Ge and other physics beyond the Standard Model. Its readout electronics were designed to have low electronic noise, and radioactive backgrounds were minimized by using low-mass components and low-radioactivity materials near the detectors. This paper provides a description of all components of the MAJORANA DEMONSTRATOR readout electronics, spanning the front-end electronics and internal cabling, back-end electronics, digitizer, and power supplies, along with the grounding scheme. The spectroscopic performance achieved with these readout electronics is also demonstrated., Comment: For submission to JINST, 17 figures. v2: revised version

Published
2021
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4. The Majorana Demonstrator readout electronics system

Author

Abgrall, N, Amman, M, Arnquist, IJ, Avignone, FT, Barabash, AS, Barton, CJ, Barton, PJ, Bertrand, FE, Bhimani, KH, Bos, B, Bradley, AW, Burritt, TH, Busch, M, Buuck, M, Caldwell, TS, Chan, Y-D, Christofferson, CD, Chu, P-H, Clark, ML, Cooper, RJ, Cuesta, C, Detwiler, JA, Drobizhev, A, Edwins, DW, Efremenko, Yu, Ejiri, H, Elliott, SR, Gilliss, T, Giovanetti, GK, Green, MP, Gruszko, J, Guinn, IS, Guiseppe, VE, Haufe, CR, Hegedus, RJ, Henning, R, Aguilar, D Hervas, Hoppe, EW, Hostiuc, A, Kidd, MF, Kim, I, Kouzes, RT, Li, A, Loach, JC, Lopez, AM, López-Castaño, JM, Luke, PN, Martin, EL, Martin, RD, Massarczyk, R, Meijer, SJ, Mertens, S, Myslik, J, Oli, TK, Othman, G, Peterson, D, Pettus, W, Poon, AWP, Radford, DC, Rager, J, Reine, AL, Rielage, K, Robertson, RGH, Ruof, NW, Sayki, B, Stortini, MJ, Tedeschi, D, Turqueti, M, Van Wechel, TD, Varner, RL, Vasilyev, S, Vetter, K, Wilkerson, JF, Wiseman, C, Xu, W, Yaver, H, Yu, C-H, Zhu, BX, and Zimmermann, S

Subjects
Nuclear and Plasma Physics, Synchrotrons and Accelerators, Physical Sciences, Double-beta decay detectors, Electronic detector readout concepts, Front-end electronics for detector readout, Engineering, Nuclear & Particles Physics, Physical sciences
Abstract

The Majorana Demonstrator comprises two arrays of high-purity germanium detectors constructed to search for neutrinoless double-beta decay in 76Ge and other physics beyond the Standard Model. Its readout electronics were designed to have low electronic noise, and radioactive backgrounds were minimized by using low-mass components and low-radioactivity materials near the detectors. This paper provides a description of all components of the Majorana Demonstrator readout electronics, spanning the front-end electronics and internal cabling, back-end electronics, digitizer, and power supplies, along with the grounding scheme. The spectroscopic performance achieved with these readout electronics is also demonstrated.

Published
2022

5. α-event characterization and rejection in point-contact HPGe detectors

Author

Arnquist, IJ, Avignone, FT, Barabash, AS, Barton, CJ, Bertrand, FE, Blalock, E, Bos, B, Busch, M, Buuck, M, Caldwell, TS, Chan, Y-D, Christofferson, CD, Chu, P-H, Clark, ML, Cuesta, C, Detwiler, JA, Drobizhev, A, Edwards, TR, Edwins, DW, Edzards, F, Efremenko, Y, Elliott, SR, Gilliss, T, Giovanetti, GK, Green, MP, Gruszko, J, Guinn, IS, Guiseppe, VE, Haufe, CR, Hegedus, RJ, Henning, R, Aguilar, D Hervas, Hoppe, EW, Hostiuc, A, Kim, I, Kouzes, RT, Lopez, AM, López-Castaño, JM, Martin, EL, Martin, RD, Massarczyk, R, Meijer, SJ, Mertens, S, Myslik, J, Oli, TK, Othman, G, Pettus, W, Poon, AWP, Radford, DC, Rager, J, Reine, AL, Rielage, K, Ruof, NW, Saykı, B, Schönert, S, Stortini, MJ, Tedeschi, D, Varner, RL, Vasilyev, S, Wilkerson, JF, Willers, M, Wiseman, C, Xu, W, Yu, C-H, and Zhu, BX

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Synchrotrons and Accelerators, Physical Sciences, Clinical Research, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Astronomical sciences, Atomic, molecular and optical physics, Particle and high energy physics
Abstract

P-type point contact (PPC) HPGe detectors are a leading technology for rare event searches due to their excellent energy resolution, low thresholds, and multi-site event rejection capabilities. We have characterized a PPC detector's response to α particles incident on the sensitive passivated and p + surfaces, a previously poorly-understood source of background. The detector studied is identical to those in the Majorana Demonstrator experiment, a search for neutrinoless double-beta decay ( 0νββ ) in 76 Ge. α decays on most of the passivated surface exhibit significant energy loss due to charge trapping, with waveforms exhibiting a delayed charge recovery (DCR) signature caused by the slow collection of a fraction of the trapped charge. The DCR is found to be complementary to existing methods of α identification, reliably identifying α background events on the passivated surface of the detector. We demonstrate effective rejection of all surface α events (to within statistical uncertainty) with a loss of only 0.2% of bulk events by combining the DCR discriminator with previously-used methods. The DCR discriminator has been used to reduce the background rate in the 0νββ region of interest window by an order of magnitude in the Majorana Demonstrator  and will be used in the upcoming LEGEND-200 experiment.

Published
2022

6. $\alpha$-event Characterization and Rejection in Point-Contact HPGe Detectors

Author

The MAJORANA Collaboration, Arnquist, I. J., Avignone III, F. T., Barabash, A. S., Barton, C. J., Bertrand, F. E., 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., Drobizhev, A., Edwards, T. R., Edwins, D. W., Efremenko, Yu., Elliott, S. R., Gilliss, T., Giovanetti, G. K., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Haufe, C. R., Hegedus, R. J., Henning, R., Aguilar, D. Hervas, Hoppe, E. W., Hostiuc, A., Kim, I., Kouzes, R. T., Lopez, A. M., López-Castaño, J. M., Martin, E. L., Martin, R. D., Massarczyk, R., Meijer, S. J., Mertens, S., Myslik, J., Oli, T. K., Othman, G., Pettus, W., Poon, A. W. P., Radford, D. C., Rager, J., Reine, A. L., Rielage, K., Ruof, N. W., Saykı, B., Schönert, S., Stortini, M. J., Tedeschi, D., Varner, R. L., Vasilyev, S., Wilkerson, J. F., Willers, M., Wiseman, C., Xu, W., Yu, C. -H., and Zhu, B. X.

Subjects
Physics - Instrumentation and Detectors, High Energy Physics - Experiment, Nuclear Experiment
Abstract

P-type point contact (PPC) HPGe detectors are a leading technology for rare event searches due to their excellent energy resolution, low thresholds, and multi-site event rejection capabilities. We have characterized a PPC detector's response to $\alpha$ particles incident on the sensitive passivated and p+ surfaces, a previously poorly-understood source of background. The detector studied is identical to those in the MAJORANA DEMONSTRATOR experiment, a search for neutrinoless double-beta decay ($0\nu\beta\beta$) in $^{76}$Ge. $\alpha$ decays on most of the passivated surface exhibit significant energy loss due to charge trapping, with waveforms exhibiting a delayed charge recovery (DCR) signature caused by the slow collection of a fraction of the trapped charge. The DCR is found to be complementary to existing methods of $\alpha$ identification, reliably identifying $\alpha$ background events on the passivated surface of the detector. We demonstrate effective rejection of all surface $\alpha$ events (to within statistical uncertainty) with a loss of only 0.2% of bulk events by combining the DCR discriminator with previously-used methods. The DCR discriminator has been used to reduce the background rate in the $0\nu\beta\beta$ region of interest window by an order of magnitude in the MAJORANA DEMONSTRATOR, and will be used in the upcoming LEGEND-200 experiment., Comment: Accepted for publication in European Journal of Physics C

Published
2020
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7. ADC Nonlinearity Correction for the MAJORANA DEMONSTRATOR

Author

Abgrall, N., Allmond, J. M., Arnquist, I. J., Avignone III, F. T., Barabash, A. S., Barton, C. J., Bertrand, F. E., Bos, B., Busch, M., Buuck, M., Caldwell, T. S., Campbell, C. M., Chan, Y-D., Christofferson, C. D., Chu, P. -H., Clark, M. L., Crawford, H. L., Cuesta, C., Detwiler, J. A., Drobizhev, A., Edwins, D. W., Efremenko, Yu., Ejiri, H., Elliott, S. R., Gilliss, T., Giovanetti, G. K., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Haufe, C. R., Hegedus, R. J., Henning, R., Aguilar, D. Hervas, Hoppe, E. W., Hostiuc, A., Kidd, M. F., Kim, I., Kouzes, R. T., Lopez, A. M., Lopez-Castano, J. M., Martin, E. L., Martin, R. D., Massarczyk, R., Meijer, S. J., Mertens, S., Myslik, J., Oli, T. K., Othman, G., Pettus, W., Poon, A. W. P., Radford, D. C., Rager, J., Reine, A. L., Rielage, K., Ruof, N. W., Stortini, M. J., Tedeschi, D., Varner, R. L., Vasilyev, S., White, B. R., Wilkerson, J. F., Wiseman, C., Xu, W., Yu, C. -H., Zhu, B. X., and Shanks, B.

Subjects
Physics - Instrumentation and Detectors, Nuclear Experiment
Abstract

Imperfections in analog-to-digital conversion (ADC) cannot be ignored when signal digitization requirements demand both wide dynamic range and high resolution, as is the case for the Majorana Demonstrator 76Ge neutrinoless double beta decay search. Enabling the experiment's high-resolution spectral analysis and efficient pulse shape discrimination required careful measurement and correction of ADC nonlinearites. A simple measurement protocol was developed that did not require sophisticated equipment or lengthy data taking campaigns. A slope-dependent hysteresis was observed and characterized. A correction applied to digitized waveforms prior to signal processing reduced the differential and integral nonlinearites by an order of magnitude, eliminating these as dominant contributions to the systematic energy uncertainty at the double-beta decay Q value.

Published
2020
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8. A Low Energy Rare Event Search with the Majorana Demonstrator

Author

MAJORANA Collaboration, Wiseman, C., Arnquist, I. J., Avignone III, F. T., Barabash, A. S., Barton, C. J., Bertrand, F. 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., Drobizhev, A., Edwins, D. W., Efremenko, Yu., Ejiri, H., Elliott, S. R., Gilliss, T., Giovanetti, G. K., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Haufe, C. R., Hegedus, R. J., Henning, R., Aguilar, D. Hervas, Hoppe, E. W., Hostiuc, A., Kidd, M. F., Kim, I., Kouzes, R. T., Lopez, A. M., Lopez-Castano, J. M., Martin, E. L., Martin, R. D., Massarczyk, R., Meijer, S. J., Mertens, S., Myslik, J., Oli, T. K., Othman, G., Pettus, W., Poon, A. W. P., Radford, D. C., Rager, J., Reine, A. L., Rielage, K., Ruof, N. W., Sayki, B., Stortini, M. J., Tedeschi, D., Varner, R. L., Wilkerson, J. F., Xu, W., Yu, C. -H., and Zhu, B. X.

Subjects
Nuclear Experiment, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

The MAJORANA DEMONSTRATOR is sensitive to rare events near its energy threshold, including bosonic dark matter, solar axions, and lightly ionizing particles. In this analysis, a novel training set of low energy small-angle Compton scatter events is used to determine the efficiency of pulse shape analysis cuts, and we present updated bosonic dark matter and solar axion results from an 11.17 kg-y dataset using a 5 keV analysis threshold., Comment: 4 pages, 4 figures. Proceedings of the 16th International Conference on Topics in Astroparticle and Underground Physics (TAUP 2019), September 9-13, 2019, Toyama, Japan

Published
2019
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9. Results of the MAJORANA DEMONSTRATOR's Search for Double-Beta Decay of $^{76}$Ge to Excited States of $^{76}$Se

Author

Guinn, I. S., Arnquist, I. J., Avignone III, F. T., Barabash, A. S., Barton, C. J., Bertrand, F. 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., Drobizhev, A., Edwins, D. W., Efremenko, Yu., Ejiri, H., Elliott, S. R., Gilliss, T., Giovanetti, G. K., Green, M. P., Gruszko, J., Guiseppe, V. E., Haufe, C. R., Hegedus, R. J., Henning, R., Aguilar, D. Hervas, Hoppe, E. W., Hostiuc, A., Kidd, M. F., Kim, I., Kouzes, R. T., Lopez, A. M., no, J. M. López-Casta, Martin, E. L., Martin, R. D., Massarczyk, R., Meijer, S. J., Mertens, S., Myslik, J., Oli, T. K., Othman, G., Pettus, W., Poon, A. W. P., Radford, D. C., Rager, J., Reine, A. L., Rielage, K., Ruof, N. W., Stortini, M. J., Tedeschi, D., Varner, R. L., Wilkerson, J. F., Wiseman, C., Xu, W., Yu, C. -H., and Zhu, B. X.

Subjects
Nuclear Experiment
Abstract

The MAJORANA DEMONSTRATOR is searching for double-beta decay of $^{76}$Ge to excited states (E.S.) in $^{76}$Se using a modular array of high purity Germanium detectors. $^{76}$Ge can decay into three E.S.s of $^{76}$Se. The E.S. decays have a clear event signature consisting of a $\beta\beta$-decay with the prompt emission of one or two $\gamma$-rays, resulting in with high probability in a multi-site event. The granularity of the DEMONSTRATOR detector array enables powerful discrimination of this event signature from backgrounds. Using 21.3 kg-y of isotopic exposure, the DEMONSTRATOR has set world leading limits for each E.S. decay, with 90% CL lower half-life limits in the range of $(0.56-2.1)\cdot10^{24}$ y. In particular, for the $2\nu$ transition to the first $0^+$ E.S. of $^{76}$Se, a lower half-life limit of $0.68\cdot10^{24}$ at 90% CL was achieved.

Published
2019
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10. ADC Nonlinearity Correction for the Majorana Demonstrator

Author

Abgrall, N, Allmond, JM, Arnquist, IJ, Avignone, FT, Barabash, AS, Barton, CJ, Bertrand, FE, Bos, B, Busch, M, Buuck, M, Caldwell, TS, Campbell, CM, Chan, Y-D, Christofferson, CD, Chu, Pinghan, Clark, ML, Crawford, HL, Cuesta, C, Detwiler, JA, Drobizhev, A, Edwins, DW, Efremenko, Yu, Ejiri, H, Elliott, SR, Gilliss, T, Giovanetti, GK, Green, MP, Gruszko, J, Guinn, IS, Guiseppe, VE, Haufe, CR, Hegedus, RJ, Henning, R, Aguilar, D Hervas, Hoppe, EW, Hostiuc, A, Kidd, MF, Kim, I, Kouzes, RT, Lopez, AM, Lopez-Castano, JM, Martin, EL, Martin, RD, Massarczyk, R, Meijer, SJ, Mertens, S, Myslik, J, Oli, TK, Othman, G, Pettus, W, Poon, AWP, Radford, DC, Rager, J, Reine, AL, Rielage, K, Ruof, NW, Stortini, MJ, Tedeschi, D, Varner, RL, Vasilyev, S, White, BR, Wilkerson, JF, Wiseman, C, Xu, W, Yu, C-H, Zhu, BX, and Shanks, B

Subjects
Nuclear and Plasma Physics, Synchrotrons and Accelerators, Physical Sciences, Gamma-ray detectors, neutrinoless double-beta decay, physics.ins-det, nucl-ex, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Other Physical Sciences, Biomedical Engineering, Nuclear & Particles Physics, Nuclear and plasma physics
Abstract

Imperfections in analog-to-digital conversion (ADC) cannot be ignored when signal digitization requirements demand both wide dynamic range and high resolution, as is the case for the Majorana Demonstrator 76Ge neutrinoless double-beta decay search. Enabling the experiment's high-resolution spectral analysis and efficient pulse shape discrimination required careful measurement and correction of ADC nonlinearities. A simple measurement protocol was developed that did not require sophisticated equipment or lengthy data-taking campaigns. A slope-dependent hysteresis was observed and characterized. A correction applied to digitized waveforms prior to signal processing reduced the differential and integral nonlinearities by an order of magnitude, eliminating these as dominant contributions to the systematic energy uncertainty at the double-beta decay Q value.

Published
2021

11. A Search for Neutrinoless Double-Beta Decay in $^{76}$Ge with 26 kg-yr of Exposure from the MAJORANA DEMONSTRATOR

Author

Alvis, S. I., Arnquist, I. J., Avignone III, F. T., Barabash, A. S., Barton, C. J., Basu, V., Bertrand, F. E., Bos, B., Busch, M., Buuck, M., Caldwell, T. S., Chan, Y-D., Christofferson, C. D., Chu, P. -H., Cuesta, C., Detwiler, J. A., Efremenko, Yu., Ejiri, H., Elliott, S. R., Gilliss, T., Giovanetti, G. K., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Haufe, C. R., Hegedus, R. J., Hehn, L., Henning, R., Aguilar, D. Hervas, Hoppe, E. W., Howe, M. A., Kidd, M. F., Konovalov, S. I., Kouzes, R. T., Lopez, A. M., Martin, R. D., Massarczyk, R., Meijer, S. J., Mertens, S., Myslik, J., Othman, G., Pettus, W., Piliounis, A., Poon, A. W. P., Radford, D. C., Rager, J., Reine, A. L., Rielage, K., Ruof, N. W., Shanks, B., Shirchenko, M., Tedeschi, D., Varner, R. L., Vasilyev, S., White, B. R., Wilkerson, J. F., Wiseman, C., Xu, W., Yakushev, E., Yu, C. -H., Yumatov, V., Zhitnikov, I., and Zhu, B. X.

Subjects
Nuclear Experiment, High Energy Physics - Experiment
Abstract

The MAJORANA Collaboration is operating an array of high purity Ge detectors to search for the neutrinoless double-beta decay of $^{76}$Ge. The MAJORANA DEMONSTRATOR consists of 44.1 kg of Ge detectors (29.7 kg enriched to 88% in $^{76}$Ge) split between two modules constructed from ultra-clean materials. Both modules are contained in a low-background shield at the Sanford Underground Research Facility in Lead, South Dakota. We present updated results on the search for neutrinoless double-beta decay in $^{76}$Ge with $26.0\pm0.5$ kg-yr of enriched exposure. With the DEMONSTRATOR's unprecedented energy resolution of 2.53 keV FWHM at $Q_{\beta\beta}$, we observe one event in the region of interest with 0.65 events expected from the estimated background, resulting in a lower limit on the $^{76}$Ge neutrinoless double-beta decay half-life of $2.7\times10^{25}$ yr (90% CL) with a median sensitivity of $4.8\times10^{25}$ yr (90% CL). Depending on the matrix elements used, a 90% CL upper limit on the effective Majorana neutrino mass in the range of 200-433 meV is obtained. The measured background in the low-background configurations is $11.9\pm2.0$ counts/(FWHM t yr)., Comment: 11 pages, 11 figures

Published
2019
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12. Multi-site event discrimination for the MAJORANA DEMONSTRATOR

Author

Alvis, S. I., Arnquist, I. J., Avignone III, F. T., Barabash, A. S., Barton, C. J., Bertrand, F. E., Bos, B., Buuck, M., Caldwell, T. S., Chan, Y-D., Christofferson, C. D., Chu, P. -H., Cuesta, C., Detwiler, J. A., Ejiri, H., Elliott, S. R., Gilliss, T., Giovanetti, G. K., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Haufe, C. R., Hegedus, R. J., Hehn, L., Henning, R., Aguilar, D. Hervas, Hoppe, E. W., Howe, M. A., Keeter, K. J., Kidd, M. F., Konovalov, S. I., Kouzes, R. T., Lopez, A. M., Martin, R. D., Massarczyk, R., Meijer, S. J., Mertens, S., Myslik, J., Othman, G., Pettus, W., Piliounis, A., Poon, A. W. P., Radford, D. C., Rager, J., Reine, A. L., Rielage, K., Ruof, N. W., Shanks, B., Shirchenko, M., Tedeschi, D., Varner, R. L., Vasilyev, S., Vasundhara, White, B. R., Wilkerson, J. F., Wiseman, C., Xu, W., Yakushev, E., Yu, C. -H., Yumatov, V., Zhitnikov, I., and Zhu, B. X.

Subjects
Physics - Instrumentation and Detectors, High Energy Physics - Experiment, Nuclear Experiment
Abstract

The MAJORANA DEMONSTRATOR is searching for neutrinoless double-beta decay in 76Ge using arrays of point-contact germanium detectors operating at the Sanford Underground Research Facility. Background results in the neutrinoless double-beta decay region of interest from data taken during construction, commissioning, and the start of full operations have been recently published. A pulse shape analysis cut applied to achieve this result, named AvsE, is described in this paper. This cut is developed to remove events whose waveforms are typical of multi-site energy deposits while retaining (90 +/- 3.5)% of single-site events. This pulse shape discrimination is based on the relationship between the maximum current and energy, and tuned using 228Th calibration source data. The efficiency uncertainty accounts for variation across detectors, energy, and time, as well as for the position distribution difference between calibration and $0\nu\beta\beta$ events, established using simulations., Comment: 8 pages, 8 figures

Published
2019
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13. $α$-event Characterization and Rejection in Point-Contact HPGe Detectors

Author

Collaboration, The MAJORANA, Arnquist, IJ, III, FT Avignone, Barabash, AS, Barton, CJ, Bertrand, FE, Blalock, E, Bos, B, Busch, M, Buuck, M, Caldwell, TS, Chan, Y-D, Christofferson, CD, Chu, P-H, Clark, ML, Cuesta, C, Detwiler, JA, Drobizhev, A, Edwards, TR, Edwins, DW, Efremenko, Yu, Elliott, SR, Gilliss, T, Giovanetti, GK, Green, MP, Gruszko, J, Guinn, IS, Guiseppe, VE, Haufe, CR, Hegedus, RJ, Henning, R, Aguilar, D Hervas, Hoppe, EW, Hostiuc, A, Kim, I, Kouzes, RT, Lopez, AM, López-Castaño, JM, Martin, EL, Martin, RD, Massarczyk, R, Meijer, SJ, Mertens, S, Myslik, J, Oli, TK, Othman, G, Pettus, W, Poon, AWP, Radford, DC, Rager, J, Reine, AL, Rielage, K, Ruof, NW, Saykı, B, önert, S Sch, Stortini, MJ, Tedeschi, D, Varner, RL, Vasilyev, S, Wilkerson, JF, Willers, M, Wiseman, C, Xu, W, Yu, C-H, and Zhu, BX

Subjects
physics.ins-det, hep-ex, nucl-ex
Abstract

P-type point contact (PPC) HPGe detectors are a leading technology for rareevent searches due to their excellent energy resolution, low thresholds, andmulti-site event rejection capabilities. We have characterized a PPC detector'sresponse to $\alpha$ particles incident on the sensitive passivated and p+surfaces, a previously poorly-understood source of background. The detectorstudied is identical to those in the MAJORANA DEMONSTRATOR experiment, a searchfor neutrinoless double-beta decay ($0u\beta\beta$) in $^{76}$Ge. $\alpha$decays on most of the passivated surface exhibit significant energy loss due tocharge trapping, with waveforms exhibiting a delayed charge recovery (DCR)signature caused by the slow collection of a fraction of the trapped charge.The DCR is found to be complementary to existing methods of $\alpha$identification, reliably identifying $\alpha$ background events on thepassivated surface of the detector. We demonstrate effective rejection of allsurface $\alpha$ events (to within statistical uncertainty) with a loss of only0.2% of bulk events by combining the DCR discriminator with previously-usedmethods. The DCR discriminator has been used to reduce the background rate inthe $0u\beta\beta$ region of interest window by an order of magnitude in theMAJORANA DEMONSTRATOR, and will be used in the upcoming LEGEND-200 experiment.

Published
2020

14. Results of the MAJORANA DEMONSTRATOR's Search for Double-Beta Decay of 76Ge to Excited States of 76Se

Author

Guinn, IS, Arnquist, IJ, Avignone, FT, Barabash, AS, Barton, CJ, Bertrand, FE, Bos, B, Busch, M, Buuck, M, Caldwell, TS, Chan, YD, Christofferson, CD, Chu, PH, Clark, ML, Cuesta, C, Detwiler, JA, Drobizhev, A, Edwins, DW, Efremenko, Y, Ejiri, H, Elliott, SR, Gilliss, T, Giovanetti, GK, Green, MP, Gruszko, J, Guiseppe, VE, Haufe, CR, Hegedus, RJ, Henning, R, Hervas Aguilar, D, Hoppe, EW, Hostiuc, A, Kidd, MF, Kim, I, Kouzes, RT, Lopez, AM, López-Castano, JM, Martin, EL, Martin, RD, Massarczyk, R, Meijer, SJ, Mertens, S, Myslik, J, Oli, TK, Othman, G, Pettus, W, Poon, AWP, Radford, DC, Rager, J, Reine, AL, Rielage, K, Ruof, NW, Stortini, MJ, Tedeschi, D, Varner, RL, Wilkerson, JF, Wiseman, C, Xu, W, Yu, CH, and Zhu, BX

Subjects
nucl-ex, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Condensed Matter Physics, Other Physical Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract

The MAJORANA DEMONSTRATOR is searching for double-beta decay of 76Ge to excited states (E.S.) in 76Se using a modular array of high purity Germanium detectors. 76Ge can decay into three E.S.s of 76Se. The E.S. decays have a clear event signature consisting of a ββ-decay with the prompt emission of one or two γ-rays, resulting in with high probability in a multi-site event. The granularity of the DEMONSTRATOR detector array enables powerful discrimination of this event signature from backgrounds. Using 21.3 kg-y of isotopic exposure, the DEMONSTRATOR has set world leading limits for each E.S. decay, with 90% CL lower half-life limits in the range of (0.56 2.1) ⋅ 1024 y. In particular, for the 2v transition to the first 0+ E.S. of 76Se, a lower half-life limit of 0.68 ⋅ 1024 at 90% CL was achieved.

Published
2020

15. Initial results from the Majorana Demonstrator

Author

Caldwell, TS, Abgrall, N, Alvis, SI, Arnquist, IJ, Avignone, FT, Barabash, AS, Barton, CJ, Bertrand, FE, Bode, T, Bos, B, Bradley, AW, Brudanin, V, Busch, M, Buuck, M, Chan, YDC, Christofferson, CD, Chu, PH, Cuesta, C, Detwiler, JA, Dunagan, C, Efremenko, Y, Ejiri, H, Elliott, SR, Gilliss, T, Giovanetti, GK, Green, MP, Gruszko, J, Guinn, IS, Guiseppe, VE, Haufe, CR, Hehn, L, Henning, R, Hoppe, EW, Howe, MA, Keeter, KJ, Kidd, MF, Konovalov, SI, Kouzes, RT, Lopez, AM, Martin, RD, Massarczyk, R, Meijer, SJ, Mertens, S, Myslik, J, O'Shaughnessy, C, Othman, G, Pettus, W, Poon, AWP, Radford, DC, Rager, J, Reine, AL, Rielage, K, Robertson, RGH, Ruof, NW, Shanks, B, Shirchenko, M, Suriano, AM, Tedeschi, D, Trimble, JE, Varner, RL, Vasilyev, S, Vetter, K, Vorren, K, White, BR, Wilkerson, JF, Wiseman, C, Xu, W, Yakushev, E, Yu, CH, Yumatov, V, Zhitnikov, I, and Zhu, BX

Subjects
physics.ins-det, nucl-ex, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Condensed Matter Physics, Other Physical Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract

The Majorana Collaboration has assembled an array of high purity Ge detectors to search for neutrinoless double-beta decay in 76Ge with the goal of establishing the required background and scalability of a Ge-based next-generation ton-scale experiment. The Majorana Demonstrator consists of 44 kg of high-purity Ge (HPGe) detectors (30 kg enriched in 76Ge) with a low-noise p-Type point contact (PPC) geometry. The detectors are split between two modules which are contained in a single lead and high-purity copper shield at the Sanford Underground Research Facility in Lead, South Dakota. Following a commissioning run that started in June 2015, the full detector array has been acquiring data since August 2016. We will discuss the status of the Majorana Demonstrator and initial results from the first physics run; including current background estimates, exotic low-energy physics searches, projections on the physics reach of the Demonstrator, and implications for a ton-scale Ge-based neutrinoless double-beta decay search.

Published
2020

16. Spectral analysis for the Majorana Demonstrator experiment

Author

Hehn, L, Abgrall, N, Alvis, SI, Arnquist, IJ, Avignone, FT, Barabash, AS, Barton, CJ, Bertrand, FE, Bode, T, Bradley, AW, Brudanin, V, Busch, M, Buuck, M, Caldwell, TS, Chan, YD, Christofferson, CD, Chu, PH, Cuesta, C, Detwiler, JA, Dunagan, C, Efremenko, Y, Ejiri, H, Elliott, SR, Gilliss, T, Giovanetti, GK, Green, MP, Gruszko, J, Guinn, IS, Guiseppe, VE, Haufe, CR, Henning, R, Hoppe, EW, Howe, MA, Keeter, KJ, Kidd, MF, Konovalov, SI, Kouzes, RT, Lopez, AM, Martin, RD, Massarczyk, R, Meijer, SJ, Mertens, S, Myslik, J, O'Shaughnessy, C, Othman, G, Pettus, W, Poon, AWP, Radford, DC, Rager, J, Reine, AL, Rielage, K, Robertson, RGH, Ruof, NW, Shanks, B, Shirchenko, M, Suriano, AM, Tedeschi, D, Trimble, JE, Varner, RL, Vasilyev, S, Vetter, K, Vorren, K, White, BR, Wilkerson, JF, Wiseman, C, Xu, W, Yakushev, E, Yu, CH, Yumatov, V, Zhitnikov, I, and Zhu, BX

Subjects
physics.ins-det, nucl-ex, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Condensed Matter Physics, Other Physical Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract

The MAJORANA DEMONSTRATOR is an experiment constructed to search for neutrinoless double-beta decays in germanium-76 and to demonstrate the feasibility to deploy a ton-scale experiment in a phased and modular fashion. It consists of two modular arrays of natural and 76Ge-enriched germanium detectors totaling 44.1kg (29.7kg enriched detectors), located at the 4850' level of the Sanford Underground Research Facility in Lead, South Dakota, USA. Data taken with this setup since summer 2015 at different construction stages of the experiment show a clear reduction of the observed background index around the ROI for 0νββ-decay search due to improvements in shielding. We discuss the statistical approaches to search for a νββ-signal and derive the physics sensitivity for an expected exposure of 10kg• y from enriched detectors using a profile likelihood based hypothesis test in combination with toy Monte Carlo data.

Published
2020

17. Progress Toward A 2νββ Measurement for the Majorana Demonstrator

Author

Gilliss, T, Abgrall, N, Alvis, SI, Arnquist, IJ, Avignone, FT, Barabash, AS, Barton, CJ, Bertrand, FE, Bode, T, Bradley, AW, Brudanin, V, Busch, M, Buuck, M, Caldwell, TS, Chan, YD, Christofferson, CD, Chu, PH, Cuesta, C, Detwiler, JA, Dunagan, C, Efremenko, Y, Ejiri, H, Elliott, SR, Giovanetti, GK, Green, MP, Gruszko, J, Guinn, IS, Guiseppe, VE, Haufe, CR, Hehn, L, Henning, R, Hoppe, EW, Howe, MA, Keeter, KJ, Kidd, MF, Konovalov, SI, Kouzes, RT, Lopez, AM, Martin, RD, Massarczyk, R, Meijer, SJ, Mertens, S, Myslik, J, O'Shaughnessy, C, Othman, G, Pettus, W, Poon, AWP, Radford, DC, Rager, J, Reine, AL, Rielage, K, Robertson, RGH, Ruof, NW, Shanks, B, Shirchenko, M, Suriano, AM, Tedeschi, D, Trimble, JE, Varner, RL, Vasilyev, S, Vetter, K, Vorren, K, White, BR, Wilkerson, JF, Wiseman, C, Xu, W, Yakushev, E, Yu, CH, Yumatov, V, Zhitnikov, I, and Zhu, BX

Subjects
physics.ins-det, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Condensed Matter Physics, Other Physical Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract

The MAJORANA DEMONSTRATOR is a 76Ge-based neutrinoless double-beta decay (0νββ) experiment. Staged at the 4850 ft level of the Sanford Underground Research Facility, the DEMONSTRATOR operates an array of high-purity p-Type point contact Ge detectors deployed within a graded passive shield and an active muon veto system. The present work concerns the two-neutrino double-beta decay mode (2νββ) of 76Ge. For Ge detectors, having superior energy resolution (0.1%), this mode poses negligible background to the 0νββ mode, even for a ton-scale experiment. However, the measurement of the 2νββ mode allows for careful systematics checks of active detector mass, enrichment fraction, and pulse shape discrimination cuts related to both the 0νββ and 2νββ decay modes. A precision measurement of the 2νββ shape also allows searches for spectral distortions, possibly indicative of new physics, including 0νββχ. Work is underway to construct a full experimental background model enabling a Bayesian fit to the measured energy spectrum and extraction of a precise 2νββ spectrum and half-life.

Published
2020

18. Design improvements to cables and connectors in the Majorana Demonstrator

Author

Haufe, CR, Reine, AL, Abgrall, N, Alvis, SI, Arnquist, IJ, Avignone, FT, Barabash, AS, Barton, CJ, Bertrand, FE, Bode, T, Bradley, AW, Brudanin, V, Busch, M, Buuck, M, Caldwell, TS, Chan, YD, Christofferson, CD, Chu, PH, Cuesta, C, Detwiler, JA, Dunagan, C, Efremenko, Y, Ejiri, H, Elliott, SR, Gilliss, T, Giovanetti, GK, Green, MP, Gruszko, J, Guinn, IS, Guiseppe, VE, Hehn, L, Henning, R, Hoppe, EW, Howe, MA, Keeter, KJ, Kidd, MF, Konovalov, SI, Kouzes, RT, Lopez, AM, Martin, RD, Massarczyk, R, Meijer, SJ, Mertens, S, Myslik, J, O'Shaughnessy, C, Othman, G, Pettus, W, Poon, AWP, Radford, DC, Rager, J, Rielage, K, Robertson, RGH, Ruof, NW, Shanks, B, Shirchenko, M, Suriano, AM, Tedeschi, D, Trimble, JE, Varner, RL, Vasilyev, S, Vetter, K, Vorren, K, White, BR, Wilkerson, JF, Wiseman, C, Xu, W, Yakushev, E, Yu, CH, Yumatov, V, Zhitnikov, I, and Zhu, BX

Subjects
physics.ins-det, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Condensed Matter Physics, Other Physical Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract

The MAJORANA DEMONSTRATOR is an experiment constructed to search for neutrinoless double-beta decays in germanium-76 and to demonstrate the feasibility to deploy a ton-scale experiment in a phased and modular fashion. It consists of two modular arrays of natural and 76Ge-enriched germanium p-Type point contact detectors totaling 44.1 kg, located at the 4850' level of the Sanford Underground Research Facility in Lead, South Dakota, USA. The DEMONSTRATOR uses custom high voltage cables to bias the detectors, as well as custom signal cables and connectors to read out the charge deposited at each detectors point contact. These low-mass cables and connectors must meet stringent radiopurity requirements while being subjected to thermal and mechanical stress. A number of issues have been identified with the currently installed cables and connectors. An improved set of cables and connectors for the MAJORANA DEMONSTRATOR are being developed with the aim of increasing their overall reliability and connectivity. We will discuss some of the issues encountered with the current cables and connectors as well as our improved designs and their initial performance.

Published
2020

19. Data quality assurance for the Majorana Demonstrator

Author

Myslik, J, Abgrall, N, Alvis, SI, Arnquist, IJ, Avignone, FT, Barabash, AS, Barton, CJ, Bertrand, FE, Bode, T, Bradley, AW, Brudanin, V, Busch, M, Buuck, M, Caldwell, TS, Chan, YD, Christofferson, CD, Chu, PH, Cuesta, C, Detwiler, JA, Dunagan, C, Efremenko, Y, Ejiri, H, Elliott, SR, Gilliss, T, Giovanetti, GK, Green, MP, Gruszko, J, Guinn, IS, Guiseppe, VE, Haufe, CR, Hehn, L, Henning, R, Hoppe, EW, Howe, MA, Keeter, KJ, Kidd, MF, Konovalov, SI, Kouzes, RT, Lopez, AM, Martin, RD, Massarczyk, R, Meijer, SJ, Mertens, S, O'Shaughnessy, C, Othman, G, Pettus, W, Poon, AWP, Radford, DC, Rager, J, Reine, AL, Rielage, K, Robertson, RGH, Ruof, NW, Shanks, B, Shirchenko, M, Suriano, AM, Tedeschi, D, Trimble, JE, Varner, RL, Vasilyev, S, Vetter, K, Vorren, K, White, BR, Wilkerson, JF, Wiseman, C, Xu, W, Yakushev, E, Yu, CH, Yumatov, V, Zhitnikov, I, and Zhu, BX

Subjects
physics.ins-det, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Condensed Matter Physics, Other Physical Sciences
Abstract

The MAJORANA DEMONSTRATOR is an experiment constructed to search for neutrinoless double-beta decays in germanium-76 and to demonstrate the feasibility to deploy a large-scale experiment in a phased and modular fashion. It consists of two modular arrays of natural and 76 Ge-enriched germanium detectors totalling 44.1 kg, located at the 4850' level of the Sanford Underground Research Facility in Lead, South Dakota, USA. Any neutrinoless double-beta decay search requires a thorough understanding of the background and the signal energy spectra. The various techniques employed to ensure the integrity of the measured spectra are discussed. Data collection is monitored with a thorough set of checks, and subsequent careful analysis is performed to qualify the data for higher level physics analysis. Instrumental background events are tagged for removal, and problematic channels are removed from consideration as necessary.

Published
2020

20. Status update of the majorana demonstrator neutrinoless double beta decay experiment

Author

Gruszko, J, Buuck, M, Cuesta, C, Detwiler, JA, Guinn, IS, Leon, J, Robertson, RGH, Abgrall, N, Bradley, AW, Chan, YD, Mertens, S, Poon, AWP, Arnquist, IJ, Hoppe, EW, Kouzes, RT, LaFerriere, BD, Orrell, JL, Avignone, FT, Barabash, AS, Konovalov, SI, Yumatov, V, Bertrand, FE, Galindo-Uribarri, A, Radford, DC, Varner, RL, White, BR, Yu, CH, Brudanin, V, Shirchenko, M, Vasilyev, S, Yakushev, E, Zhitnikov, I, Busch, M, Byram, D, Jasinski, BR, Snyder, N, Caldwell, AS, Christofferson, CD, Dunagan, C, Howard, S, Suriano, AM, Chu, PH, Elliott, SR, Goett, J, Massarczyk, R, Rielage, K, Xu, W, Efremenko, Y, Ejiri, H, Gilliss, T, Giovanetti, GK, Henning, R, Howe, MA, MacMullin, J, Meijer, SJ, O'Shaughnessy, C, Rager, J, Shanks, B, Trimble, JE, Vorren, K, Green, MP, Guiseppe, VE, Tedeschi, D, Wiseman, C, Keeter, KJ, Kidd, MF, Martin, RD, Romero-Romero, E, Vetter, K, and Wilkerson, JF

Subjects
physics.ins-det, nucl-ex
Abstract

Neutrinoless double beta decay searches play a major role in determining neutrino properties, in particular the Majorana or Dirac nature of the neutrino and the absolute scale of the neutrino mass. The consequences of these searches go beyond neutrino physics, with implications for Grand Unification and leptogenesis. The Majorana Collaboration is assembling a low-background array of high purity Germanium (HPGe) detectors to search for neutrinoless double-beta decay in 76Ge. The Majorana Demonstrator, which is currently being constructed and commissioned at the Sanford Underground Research Facility in Lead, South Dakota, will contain 44 kg (30 kg enriched in 76Ge) of HPGe detectors. Its primary goal is to demonstrate the scalability and background required for a tonne-scale Ge experiment. This is accomplished via a modular design and projected background of less than 3 cnts/tonne-yr in the region of interest. The experiment is currently taking data with the first of its enriched detectors.

Published
2020

21. Recent results from the MAJORANA DEMONSTRATOR

Author

Myslik, J., Alvis, S. I., Arnquist, I. J., Avignone III, F. T., Barabash, A. S., Barton, C. J., Bertrand, F. E., Bode, T., Bos, B., Brudanin, V., Busch, M., Buuck, M., Caldwell, T. S., Chan, Y-D., Christofferson, C. D., Chu, P. -H., Cuesta, C., Detwiler, J. A., Dunagan, C., Efremenko, Yu., Ejiri, H., Elliott, S. R., Gilliss, T., Giovanetti, G. K., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Haufe, C. R., Hegedus, R. J., Hehn, L., Henning, R., Aguilar, D. Hervas, Hoppe, E. W., Howe, M. A., Keeter, K. J., Kidd, M. F., Konovalov, S. I., Kouzes, R. T., Lopez, A. M., Martin, R. D., Massarczyk, R., Meijer, S. J., Mertens, S., Othman, G., Pettus, W., Piliounis, A., Poon, A. W. P., Radford, D. C., Rager, J., Reine, A. L., Rielage, K., Ruof, N. W., Shanks, B., Shirchenko, M., Tedeschi, D., Varner, R. L., Vasilyev, S., Vasundhara, White, B. R., Wilkerson, J. F., Wiseman, C., Xu, W., Yakushev, E., Yu, C. -H., Yumatov, V., Zhitnikov, I., and Zhu, B. X.

Subjects
Physics - Instrumentation and Detectors, Nuclear Experiment
Abstract

The MAJORANA DEMONSTRATOR is an experiment constructed to search for neutrinoless double-beta decay in $^{76}$Ge and to demonstrate the feasibility to deploy a large-scale experiment in a phased and modular fashion. It consists of two modules of natural and $^{76}$Ge-enriched germanium detectors totalling 44.1 kg, operating at the 4850' level of the Sanford Underground Research Facility in Lead, South Dakota, USA. Commissioning of the experiment began in June 2015, followed by data production with the full detector array in August 2016. The ultra-low background and record energy resolution achieved by the MAJORANA DEMONSTRATOR enable a sensitive neutrinoless double-beta decay search, as well as additional searches for physics beyond the Standard Model. I will discuss the design elements that enable these searches, along with the latest results, focusing on the neutrinoless double-beta decay search. I will also discuss the current status and the future plans of the MAJORANA DEMONSTRATOR, as well as the plans for a future tonne-scale $^{76}$Ge experiment., Comment: 4 pages. Proceedings of The 39th International Conference on High Energy Physics (ICHEP2018), 4-11 July, 2018, Seoul, Korea. Submitted to Proceedings of Science

Published
2018

22. Search for Tri-Nucleon Decay in the Majorana Demonstrator

Author

Alvis, S. I., Arnquist, I. J., Avignone III, F. T., Barabash, A. S., Barton, C. J., Bertrand, F. E., Bos, B., Brudanin, V., Busch, M., Buuck, M., Caldwell, T. S., Chan, Y-D., Christofferson, C. D., Chu, P. -H., Cuesta, C., Detwiler, J. A., Efremenko, Yu., Ejiri, H., Elliott, S. R., Gilliss, T., Giovanetti, G. K., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Haufe, C. R., Hegedus, R. J., Hehn, L., Henning, R., Aguilar, D. Hervas, Hoppe, E. W., Howe, M. A., Keeter, K. J., Kidd, M. F., Konovalov, S. I., Kouzes, R. T., Lopez, A. M., Martin, R. D., Massarczyk, R., Meijer, S. J., Mertens, S., Myslik, J., Othman, G., Pettus, W., Piliounis, A., Poon, A. W. P., Radford, D. C., Rager, J., Reine, A. L., Rielage, K., Ruof, N. W., Shanks, B., Shirchenko, M., Tedeschi, D., Varner, R. L., Vasilyev, S., Vasundhara, White, B. R., Wilkerson, J. F., Wiseman, C., Xu, W., Yakushev, E., Yu, C. -H., Yumatov, V., Zhitnikov, I., and Zhu, B. X.

Subjects
High Energy Physics - Experiment, Nuclear Experiment, Physics - Instrumentation and Detectors
Abstract

The Majorana Demonstrator is an ultra low-background experiment searching for neutrinoless double-beta decay in $^{76}$Ge. The heavily shielded array of germanium detectors, placed nearly a mile underground at the Sanford Underground Research Facility in Lead, South Dakota, also allows searches for new exotic physics. We present the first limits for tri-nucleon decay-specific modes and invisible decay modes for Ge isotopes. We find a half-life limit of $4.9 \times 10^{25}$ yr for the decay $^{76}{\rm Ge(ppn)} \to {}^{73}{\rm Zn}\ e^+\pi^+$ and $4.7\times10^{25}$ yr for the decay $^{76}{\rm Ge(ppp)} \to ^{73}{\rm Cu}\ e^+\pi^+\pi^+$. The half-life limit for the invisible tri-proton decay mode of $^{76}$Ge was found to be $7.5\times10^{24}$ yr., Comment: Updated after suggested figure additions from referees

Published
2018
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23. Recent Results from the Majorana Demonstrator

Author

Gilliss, T, Alvis, S I, Arnquist, I J, Avignone III, F T, Barabash, A S, Barton, C J, Bertrand, F E, Bode, T, Brudanin, V, Busch, M, Buuck, M, Caldwell, T S, Chan, Y-D, Christofferson, C D, Chu, P -H, Cuesta, C, Detwiler, J A, Dunagan, C, Efremenko, Yu, Ejiri, H, Elliott, S R, Giovanetti, G K, Green, M P, Gruszko, J, Guinn, I S, Guiseppe, V E, Haufe, C R, Hehn, L, Henning, R, Hoppe, E W, Howe, M A, Keeter, K J, Kidd, M F, Konovalov, S I, Kouzes, R T, Lopez, A M, Martin, R D, Massarczyk, R, Meijer, S J, Mertens, S, Myslik, J, O'Shaughnessy, C, Othman, G, Pettus, W, Poon, A W P, Radford, D C, Rager, J, Reine, A L, Rielage, K, Robertson, R G H, Ruof, N W, Shanks, B, Shirchenko, M, Suriano, A M, Tedeschi, D, Varner, R L, Vasilyev, S, Vetter, K, Vorren, K, White, B R, Wilkerson, J F, Wiseman, C, Xu, W, Yakushev, E, Yu, C -H, Yumatov, V, Zhitnikov, I, and Zhu, B X

Subjects
Physics - Instrumentation and Detectors
Abstract

The MAJORANA Collaboration has completed construction and is now operating an array of high purity Ge detectors searching for neutrinoless double-beta decay ($0\nu\beta\beta$) in $^{76}$Ge. The array, known as the MAJORANA DEMONSTRATOR, is comprised of 44 kg of Ge detectors (30 kg enriched to 88% in $^{76}$Ge) installed in an ultra-low background compact shield at the Sanford Underground Research Facility in Lead, South Dakota. The primary goal of the DEMONSTRATOR is to establish a low-background design that can be scaled to a next-generation tonne-scale experiment. This work reports initial background levels in the $0\nu\beta\beta$ region of interest. Also presented are recent physics results leveraging P-type point-contact detectors with sub-keV energy thresholds to search for physics beyond the Standard Model; first results from searches for bosonic dark matter, solar axions, Pauli exclusion principle violation, and electron decay have been published. Finally, this work discusses the proposed tonne-scale $^{76}$Ge $0\nu\beta\beta$ LEGEND experiment., Comment: 6 pages, 1 figure, PANIC 2017: 21st Particles and Nuclei International Conference

Published
2018
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24. First Limit on the Direct Detection of Lightly Ionizing Particles for Electric Charge as Low as $e$/1000 with the \textsc{Majorana Demonstrator}

Author

Alvis, S. I., Arnquist, I. J., Avignone III, F. T., Barabash, A. S., Barton, C. J., Bertrand, F. E., Brudanin, V., Busch, M., Buuck, M., Caldwell, T. S., Chan, Y-D., Christofferson, C. D., Chu, P. -H., Cuesta, C., Detwiler, J. A., Dunagan, C., Efremenko, Yu., Ejiri, H., Elliott, S. R., Gilliss, T., Giovanetti, G. K., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Haufe, C. R., Hehn, L., Henning, R., Hoppe, E. W., Howe, M. A., Konovalov, S. I., Kouzes, R. T., Lopez, A. M., Martin, R. D., Massarczyk, R., Meijer, S. J., Mertens, S., Myslik, J., O'Shaughnessy, C., Othman, G., Pettus, W., Poon, A. W. P., Radford, D. C., Rager, J., Reine, A. L., Rielage, K., Robertson, R. G. H., Ruof, N. W., Shanks, B., Shirchenko, M., Suriano, A. M., Tedeschi, D., Varner, R. L., Vasilyev, S., Vorren, K., White, B. R., Wilkerson, J. F., Wiseman, C., Xu, W., Yakushev, E., Yu, C. -H., Yumatov, V., Zhitnikov, I., and Zhu, B. X.

Subjects
High Energy Physics - Experiment, Astrophysics - Cosmology and Nongalactic Astrophysics, Physics - Instrumentation and Detectors
Abstract

The \textsc{Majorana Demonstrator} is an ultra low-background experiment searching for neutrinoless double-beta decay in $^{76}$Ge. The heavily shielded array of germanium detectors, placed nearly a mile underground at the Sanford Underground Research Facility in Lead, South Dakota, also allows searches for new exotic physics. Free, relativistic, lightly-ionizing particles with electrical charges less than $e$ are forbidden by the standard model but predicted by some of its extensions. If such particles exist, they might be detected in the \textsc{Majorana Demonstrator} by searching for multiple- detector events with individual-detector energy depositions down to 1 keV. This search is background free and no candidate events have been found in 285 days of data taking. New direct-detection limits are set for the flux of lightly ionizing particles for charges as low as $e$/1000., Comment: final version

Published
2018
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25. Low Background Materials and Fabrication Techniques for Cables and Connectors in the Majorana Demonstrator

Author

Busch, M., Abgrall, N., Alvis, S. I., Arnquist, I. J., Avignone III, F. T., Barabash, A. S., Barton, C. J., Bertrand, F. E., Bode, T., Bradley, A. W., Brudanin, V., Buuck, M., Caldwell, T. S., Chan, Y-D., Christofferson, C. D., Chu, P. -H., Cuesta, C., Detwiler, J. A., Dunagan, C., Efremenko, Yu., Ejiri, H., Elliott, S. R., Gilliss, T., Giovanetti, G. K., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Haufe, C. R., Hehn, L., Henning, R., Hoppe, E. W., Howe, M. A., Keeter, K. J., Kidd, M. F., Konovalov, S. I., Kouzes, R. T., Lopez, A. M., Martin, R. D., Massarczyk, R., Meijer, S. J., Mertens, S., Myslik, J., O'Shaughnessy, C., Othman, G., Poon, A. W. P., Radford, D. C., Rager, J., Reine, A. L., Rielage, K., Robertson, R. G. H., Rouf, N. W., Shanks, B., Shirchenko, M., Suriano, A. M., Tedeschi, D., Trimble, J. E., Varner, R. L., Vasilyev, S., Vetter, K., Vorren, K., White, B. R., Wilkerson, J. F., Wiseman, C., Xu, W., Yakushev, E., Yu, C. -H., Yumatov, V., Zhitnikov, I., and Zhu, B. X.

Subjects
Physics - Instrumentation and Detectors
Abstract

The MAJORANA Collaboration is searching for the neutrinoless double-beta decay of the nucleus Ge-76. The MAJORANA DEMONSTRATOR is an array of germanium detectors deployed with the aim of implementing background reduction techniques suitable for a tonne scale Ge-76-based search (the LEGEND collaboration). In the DEMONSTRATOR, germanium detectors operate in an ultra-pure vacuum cryostat at 80 K. One special challenge of an ultra-pure environment is to develop reliable cables, connectors, and electronics that do not significantly contribute to the radioactive background of the experiment. This paper highlights the experimental requirements and how these requirements were met for the MAJORANA DEMONSTRATOR, including plans to upgrade the wiring for higher reliability in the summer of 2018. Also described are requirements for LEGEND R&D efforts underway to meet these additional requirements., Comment: Proceedings of LRT 2017

Published
2017
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26. Design improvements to cables and connectors in the Majorana Demonstrator

Author

Haufe, C. R., Reine, A. L., Abgrall, N., Alvis, S. I., Arnquist, I. J., Avignone III, F. T., Barabash, A. S., Barton, C. J., Bertrand, F. E., Bode, T., Bradley, A. W., Brudanin, V., Busch, M., Buuck, M., Caldwell, T. S., Chan, Y. -D., Christofferson, C. D., Chu, P. -H., Cuesta, C., Detwiler, J. A., Dunagan, C., Efremenko, Yu., Ejiri, H., Elliott, S. R., Gilliss, T., Giovanetti, G. K., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Hehn, L., Henning, R., Hoppe, E. W., Howe, M. A., Keeter, K. J., Kidd, M. F., Konovalov, S. I., Kouzes, R. T., Lopez, A. M., Martin, R. D., Massarczyk, R., Meijer, S. J., Mertens, S., Myslik, J., O'Shaughnessy, C., Othman, G., Pettus, W., Poon, A. W. P., Radford, D. C., Rager, J., Rielage, K., Robertson, R. G. H., Ruof, N. W., Shanks, B., Shirchenko, M., Suriano, A. M., Tedeschi, D., Trimble, J. E., Varner, R. L., Vasilyev, S., Vetter, K., Vorren, K., White, B. R., Wilkerson, J. F., Wiseman, C., Xu, W., Yakushev, E., Yu, C. -H., Yumatov, V., Zhitnikov, I., and Zhu, B. X.

Subjects
Physics - Instrumentation and Detectors
Abstract

The Majorana Demonstrator is an experiment constructed to search for neutrinoless double-beta decays in germanium-76 and to demonstrate the feasibility to deploy a ton-scale experiment in a phased and modular fashion. It consists of two modular arrays of natural and 76Ge-enriched germanium p-type point contact detectors totaling 44.1 kg, located at the 4850 level of the Sanford Underground Research Facility in Lead, South Dakota, USA. The Demonstrator uses custom high voltage cables to bias the detectors, as well as custom signal cables and connectors to read out the charge deposited at the point contact of each detector. These low-mass cables and connectors must meet stringent radiopurity requirements while being subjected to thermal and mechanical stress. A number of issues have been identified with the currently installed cables and connectors. An improved set of cables and connectors for the Majorana Demonstrator are being developed with the aim of increasing their overall reliability and connectivity. We will discuss some of the issues encountered with the current cables and connectors as well as our improved designs and their initial performance., Comment: 5 pages, 2 figures, TAUP 2017: XV International Conference on Topics in Astroparticle and Underground Physics

Published
2017

27. Recent results of the Majorana Demonstrator experiment

Author

López-Castaño, JM, Alvis, SI, Arnquist, IJ, Avignone, FT, Barabash, AS, Barton, CJ, Basu, V, Bertrand, FE, Bos, B, Brudanin, V, Busch, M, Buuck, M, Caldwell, TS, Chan, Y-D, Christofferson, CD, Chu, P-H, Clark, ML, Cuesta, C, Detwiler, JA, Drobizhev, A, Edwins, DW, Efremenko, Yu, Ejiri, H, Elliott, SR, Gilliss, T, Giovanetti, GK, Green, MP, Gruszko, J, Guinn, IS, Guiseppe, VE, Haufe, CR, Hegedus, RJ, Henning, R, Aguilar, D Hervas, Hoppe, EW, Hostiuc, A, Howe, MA, Keeter, KJ, Kidd, MF, Konovalov, SI, Kouzes, RT, Lopez, AM, Martin, E, Martin, RD, Massarczyk, R, Meijer, SJ, Mertens, S, Myslik, J, Oli, TK, Othman, G, Pettus, W, Piliounis, A, Poon, AWP, Radford, DC, Rager, J, Reine, AL, Rielage, K, Ruof, NW, Shanks, B, Shirchenko, M, Tedeschi, D, Varner, RL, Vasilyev, S, White, BR, Wilkerson, JF, Wiseman, C, Xu, W, Yakushev, E, Yu, C-H, Yumatov, V, Zhitnikov, I, and Zhu, BX

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences
Abstract

The Majorana Demonstrator is searching for neutrinoless double-beta decay in 76Ge with two modular arrays of natural and 76Ge-enriched germanium detectors. It is located at the 4850' level of Sanford Underground Research Facility in Lead, South Dakota, USA, and its total mass of germanium detectors is 44.1 kg, of which 29.7 kg is enriched. The analysis of the first 26 kg-yr of data provides an unprecedented energy resolution of 0.13% in the region of interest at 2039 keV and a background level of 15.4 ±2.0 counts/(FWHM t yr). It establishes the lower limit of the half-life of neutrinoless double beta decay as 2.7 1025 yr in 76Ge at 90% CL. This analysis will be summarized here with an emphasis on the energy determination.

Published
2019

28. Search for neutrinoless double- β decay in Ge 76 with 26 kg yr of exposure from the M ajorana D emonstrator SEARCH for NEUTRINOLESS DOUBLE- β DECAY ... S. I. ALVIS et al.

Author

Cuesta, C, Alvis, SI, Arnquist, IJ, Avignone, FT, Barabash, AS, Barton, CJ, Basu, V, Bertrand, FE, Bos, B, Busch, M, Buuck, M, Caldwell, TS, Chan, YD, Christofferson, CD, Chu, PH, Clark, M, Detwiler, JA, Efremenko, Y, Ejiri, H, Elliott, SR, Gilliss, T, Giovanetti, GK, Green, MP, Gruszko, J, Guinn, IS, Guiseppe, VE, Haufe, CR, Hegedus, RJ, Hehn, L, Henning, R, Hervas Aguilar, D, Hoppe, EW, Howe, MA, Kidd, MF, Konovalov, SI, Kouzes, RT, Lopez, AM, Martin, RD, Massarczyk, R, Meijer, SJ, Mertens, S, Myslik, J, Othman, G, Pettus, W, Piliounis, A, Poon, AWP, Radford, DC, Rager, J, Reine, AL, Rielage, K, Ruof, NW, Shanks, B, Shirchenko, M, Tedeschi, D, Varner, RL, Vasilyev, S, White, BR, Wilkerson, JF, Wiseman, C, Xu, W, Yakushev, E, Yu, CH, Yumatov, V, Zhitnikov, I, and Zhu, BX

Subjects
nucl-ex, hep-ex
Abstract

The Majorana Collaboration is operating an array of high-purity Ge detectors to search for the neutrinoless double-β decay of Ge76. The Majorana Demonstrator consists of 44.1 kg of Ge detectors (29.7 kg enriched to 88% in Ge76) split between two modules constructed from ultraclean materials. Both modules are contained in a low-background shield at the Sanford Underground Research Facility in Lead, South Dakota. We present updated results on the search for neutrinoless double-β decay in Ge76 with 26.0±0.5 kg yr of enriched exposure. With the Demonstrator's energy resolution of 2.53 keV FWHM at Qββ, which is the best among all neutrinoless double-β decay experiments, we observe one event in the region of interest with 0.65 events expected from the estimated background, resulting in a lower limit on the Ge76 neutrinoless double-β decay half-life of 2.7×1025 yr [90% confidence level (CL)] with a median sensitivity of 4.8×1025 yr (90% CL). Depending on the matrix elements used, a 90% CL upper limit on the effective Majorana neutrino mass in the range of 200-433 meV is obtained. The measured background in the configurations with full shielding and optimized grounding is 11.9±2.0 counts/(FWHM t yr).

Published
2019

29. Recent results from the MAJORANA DEMONSTRATOR

Author

Myslik, Jordan, Alvis, SI, Arnquist, IJ, Avignone III, FT, Barabash, AS, Barton, CJ, Bertrand, FE, Bode, T, Bos, B, Brudanin, V, Busch, M, Buuck, M, Caldwell, TS, Chan, Y-D, Christofferson, CD, Chu, P-H, Cuesta, C, Detwiler, JA, Dunagan, C, Efremenko, Yu, Ejiri, H, Elliott, SR, Gilliss, T, Giovanetti, GK, Green, MP, Gruszko, J, Guinn, IS, Guiseppe, VE, Haufe, CR, Hegedus, RJ, Hehn, L, Henning, R, Hervas Aguilar, D, Hoppe, EW, Howe, MA, Keeter, KJ, Kidd, MF, Konovalov, SI, Kouzes, RT, Lopez, AM, Martin, RD, Massarczyk, R, Meijer, SJ, Mertens, S, Othman, G, Pettus, W, Piliounis, A, Poon, AWP, Radford, DC, Rager, J, Reine, AL, Rielage, K, Ruof, NW, Shanks, B, Shirchenko, M, Tedeschi, D, Varner, RL, Vasilyev, S, Vasundhara, White, BR, Wilkerson, JF, Wiseman, C, Xu, W, Yakushev, E, Yu, C-H, Yumatov, V, Zhitnikov, I, and Zhu, BX

Abstract

The MAJORANA DEMONSTRATOR is an experiment constructed to search for neutrinoless double-beta decay in 76Ge and to demonstrate the feasibility to deploy a large-scale experiment in a phased and modular fashion. It consists of two modules of natural and 76Ge-enriched germanium detectors totalling 44.1 kg, operating at the 4850' level of the Sanford Underground Research Facility in Lead, South Dakota, USA. Commissioning of the experiment began in June 2015, followed by data production with the full detector array in August 2016. The ultra-low background and record energy resolution achieved by the MAJORANA DEMONSTRATOR enable a sensitive neutrinoless double-beta decay search, as well as additional searches for physics beyond the Standard Model. I will discuss the design elements that enable these searches, along with the latest results, focusing on the neutrinoless double-beta decay search. I will also discuss the current status and the future plans of the MAJORANA DEMONSTRATOR, as well as the plans for a future tonne-scale 76Ge experiment.

Published
2019

30. Search for neutrinoless double-β decay in Ge76 with 26 kg yr of exposure from the Majorana Demonstrator

Author

Alvis, SI, Arnquist, IJ, Avignone, FT, Barabash, AS, Barton, CJ, Basu, V, Bertrand, FE, Bos, B, Busch, M, Buuck, M, Caldwell, TS, Chan, Y-D, Christofferson, CD, Chu, P-H, Clark, M, Cuesta, C, Detwiler, JA, Efremenko, Yu, Ejiri, H, Elliott, SR, Gilliss, T, Giovanetti, GK, Green, MP, Gruszko, J, Guinn, IS, Guiseppe, VE, Haufe, CR, Hegedus, RJ, Hehn, L, Henning, R, Aguilar, D Hervas, Hoppe, EW, Howe, MA, Kidd, MF, Konovalov, SI, Kouzes, RT, Lopez, AM, Martin, RD, Massarczyk, R, Meijer, SJ, Mertens, S, Myslik, J, Othman, G, Pettus, W, Piliounis, A, Poon, AWP, Radford, DC, Rager, J, Reine, AL, Rielage, K, Ruof, NW, Shanks, B, Shirchenko, M, Tedeschi, D, Varner, RL, Vasilyev, S, White, BR, Wilkerson, JF, Wiseman, C, Xu, W, Yakushev, E, Yu, C-H, Yumatov, V, Zhitnikov, I, and Zhu, BX

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, nucl-ex, hep-ex, Nuclear and plasma physics
Abstract

The Majorana Collaboration is operating an array of high-purity Ge detectors to search for the neutrinoless double-β decay of Ge76. The Majorana Demonstrator consists of 44.1 kg of Ge detectors (29.7 kg enriched to 88% in Ge76) split between two modules constructed from ultraclean materials. Both modules are contained in a low-background shield at the Sanford Underground Research Facility in Lead, South Dakota. We present updated results on the search for neutrinoless double-β decay in Ge76 with 26.0±0.5 kg yr of enriched exposure. With the Demonstrator's energy resolution of 2.53 keV FWHM at Qββ, which is the best among all neutrinoless double-β decay experiments, we observe one event in the region of interest with 0.65 events expected from the estimated background, resulting in a lower limit on the Ge76 neutrinoless double-β decay half-life of 2.7×1025 yr [90% confidence level (CL)] with a median sensitivity of 4.8×1025 yr (90% CL). Depending on the matrix elements used, a 90% CL upper limit on the effective Majorana neutrino mass in the range of 200-433 meV is obtained. The measured background in the configurations with full shielding and optimized grounding is 11.9±2.0 counts/(FWHM t yr).

Published
2019

31. Multisite event discrimination for the majorana demonstrator

Author

Alvis, SI, Arnquist, IJ, Avignone, FT, Barabash, AS, Barton, CJ, Basu, V, Bertrand, FE, Bos, B, Buuck, M, Caldwell, TS, Chan, YD, Christofferson, CD, Chu, PH, Cuesta, C, Detwiler, JA, Ejiri, H, Elliott, SR, Gilliss, T, Giovanetti, GK, Green, MP, Gruszko, J, Guinn, IS, Guiseppe, VE, Haufe, CR, Hegedus, RJ, Hehn, L, Henning, R, Hervas Aguilar, D, Hoppe, EW, Howe, MA, Keeter, KJ, Kidd, MF, Konovalov, SI, Kouzes, RT, Lopez, AM, Martin, RD, Massarczyk, R, Meijer, SJ, Mertens, S, Myslik, J, Othman, G, Pettus, W, Piliounis, A, Poon, AWP, Radford, DC, Rager, J, Reine, AL, Rielage, K, Ruof, NW, Shanks, B, Shirchenko, M, Tedeschi, D, Varner, RL, Vasilyev, S, White, BR, Wilkerson, JF, Wiseman, C, Xu, W, Yakushev, E, Yu, CH, Yumatov, V, Zhitnikov, I, and Zhu, BX

Subjects
physics.ins-det, hep-ex, nucl-ex
Abstract

The Majorana Demonstrator is searching for neutrinoless double-beta decay (0νββ) in Ge76 using arrays of point-contact germanium detectors operating at the Sanford Underground Research Facility. Background results in the 0νββ region of interest from data taken during construction, commissioning, and the start of full operations have been recently published. A pulse shape analysis cut applied to achieve this result, named AvsE, is described in this paper. This cut is developed to remove events whose waveforms are typical of multisite energy deposits while retaining (90±3.5)% of single-site events. This pulse shape discrimination is based on the relationship between the maximum current and energy, and tuned using Th228 calibration source data. The efficiency uncertainty accounts for variation across detectors, energy, and time, as well as for the position distribution difference between calibration and 0νββ events, established using simulations.

Published
2019

32. Search for trinucleon decay in the Majorana Demonstrator

Author

Alvis, SI, Arnquist, IJ, Avignone, FT, Barabash, AS, Barton, CJ, Basu, V, Bertrand, FE, Bos, B, Brudanin, V, Busch, M, Buuck, M, Caldwell, TS, Chan, Y-D, Christofferson, CD, Chu, P-H, Cuesta, C, Detwiler, JA, Efremenko, Yu, Ejiri, H, Elliott, SR, Gilliss, T, Giovanetti, GK, Green, MP, Gruszko, J, Guinn, IS, Guiseppe, VE, Haufe, CR, Hegedus, RJ, Hehn, L, Henning, R, Aguilar, D Hervas, Hoppe, EW, Howe, MA, Keeter, KJ, Kidd, MF, Konovalov, SI, Kouzes, RT, Lopez, AM, Martin, RD, Massarczyk, R, Meijer, SJ, Mertens, S, Myslik, J, Othman, G, Pettus, W, Piliounis, A, Poon, AWP, Radford, DC, Rager, J, Reine, AL, Rielage, K, Ruof, NW, Shanks, B, Shirchenko, M, Tedeschi, D, Varner, RL, Vasilyev, S, White, BR, Wilkerson, JF, Wiseman, C, Xu, W, Yakushev, E, Yu, C-H, Yumatov, V, Zhitnikov, I, and Zhu, BX

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Synchrotrons and Accelerators, Physical Sciences, hep-ex, nucl-ex, physics.ins-det, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Astronomical sciences, Particle and high energy physics
Abstract

The Majorana Demonstrator is an ultra-low-background experiment searching for neutrinoless double-beta decay in Ge76. The heavily shielded array of germanium detectors, placed nearly a mile underground at the Sanford Underground Research Facility in Lead, South Dakota, also allows searches for new exotic physics. We present the first limits for trinucleon decay-specific modes and invisible decay modes for Ge isotopes. We find a half-life limit of 4.9×1025 yr for the decay Ge76(ppn)→Zn73 e+π+ and 4.7×1025 yr for the decay Ge76(ppp)→Cu73 e+π+π+. The half-life limit for the invisible triproton decay mode of Ge76 was found to be 7.5×1024 yr.

Published
2019

33. Recent results from the Majorana Demonstrator

Author

Myslik, J, Alvis, SI, Arnquist, IJ, Avignone, FT, Barabash, AS, Barton, CJ, Bertrand, FE, Bode, T, Bos, B, Brudanin, V, Busch, M, Buuck, M, Caldwell, TS, Chan, YD, Christofferson, CD, Chu, PH, Cuesta, C, Detwiler, JA, Dunagan, C, Efremenko, Y, Ejiri, H, Elliott, SR, Gilliss, T, Giovanetti, GK, Green, MP, Gruszko, J, Guinn, IS, Guiseppe, VE, Haufe, CR, Hegedus, RJ, Hehn, L, Henning, R, Hervas Aguilar, D, Hoppe, EW, Howe, MA, Keeter, KJ, Kidd, MF, Konovalov, SI, Kouzes, RT, Lopez, AM, Martin, RD, Massarczyk, R, Meijer, SJ, Mertens, S, Othman, G, Pettus, W, Piliounis, A, Poon, AWP, Radford, DC, Rager, J, Reine, AL, Rielage, K, Ruof, NW, Shanks, B, Shirchenko, M, Tedeschi, D, Varner, RL, Vasilyev, S, Vasundhara, White, BR, Wilkerson, JF, Wiseman, C, Xu, W, Yakushev, E, Yu, CH, Yumatov, V, Zhitnikov, I, and Zhu, BX

Subjects
Neutrinoless double-beta decay, germanium, point-contact detectors, physics.ins-det
Abstract

The MAJORANA DEMONSTRATOR is an experiment constructed to search for neutrinoless double-beta decay in 76Ge and to demonstrate the feasibility to deploy a large-scale experiment in a phased and modular fashion. It consists of two modules of natural and 76Ge-enriched germanium detectors totalling 44.1 kg, operating at the 4850' level of the Sanford Underground Research Facility in Lead, South Dakota, USA. Commissioning of the experiment began in June 2015, followed by data production with the full detector array in August 2016. The ultra-low background and record energy resolution achieved by the MAJORANA DEMONSTRATOR enable a sensitive neutrinoless double-beta decay search, as well as additional searches for physics beyond the Standard Model. I will discuss the design elements that enable these searches, along with the latest results, focusing on the neutrinoless double-beta decay search. I will also discuss the current status and the future plans of the MAJORANA DEMONSTRATOR, as well as the plans for a future tonne-scale 76Ge experiment.

Published
2019

34. Recent results from the MAJORANA DEMONSTRATOR

Author

Myslik, J, Alvis, SI, Arnquist, IJ, III, FT Avignone, Barabash, AS, Barton, CJ, Bertrand, FE, Bode, T, Bos, B, Brudanin, V, Busch, M, Buuck, M, Caldwell, TS, Chan, Y-D, Christofferson, CD, Chu, P-H, Cuesta, C, Detwiler, JA, Dunagan, C, Efremenko, Yu, Ejiri, H, Elliott, SR, Gilliss, T, Giovanetti, GK, Green, MP, Gruszko, J, Guinn, IS, Guiseppe, VE, Haufe, CR, Hegedus, RJ, Hehn, L, Henning, R, Aguilar, D Hervas, Hoppe, EW, Howe, MA, Keeter, KJ, Kidd, MF, Konovalov, SI, Kouzes, RT, Lopez, AM, Martin, RD, Massarczyk, R, Meijer, SJ, Mertens, S, Othman, G, Pettus, W, Piliounis, A, Poon, AWP, Radford, DC, Rager, J, Reine, AL, Rielage, K, Ruof, NW, Shanks, B, Shirchenko, M, Tedeschi, D, Varner, RL, Vasilyev, S, Vasundhara, White, BR, Wilkerson, JF, Wiseman, C, Xu, W, Yakushev, E, Yu, C-H, Yumatov, V, Zhitnikov, I, and Zhu, BX

Subjects
physics.ins-det, nucl-ex
Abstract

The MAJORANA DEMONSTRATOR is an experiment constructed to search forneutrinoless double-beta decay in $^{76}$Ge and to demonstrate the feasibilityto deploy a large-scale experiment in a phased and modular fashion. It consistsof two modules of natural and $^{76}$Ge-enriched germanium detectors totalling44.1 kg, operating at the 4850' level of the Sanford Underground ResearchFacility in Lead, South Dakota, USA. Commissioning of the experiment began inJune 2015, followed by data production with the full detector array in August2016. The ultra-low background and record energy resolution achieved by theMAJORANA DEMONSTRATOR enable a sensitive neutrinoless double-beta decay search,as well as additional searches for physics beyond the Standard Model. I willdiscuss the design elements that enable these searches, along with the latestresults, focusing on the neutrinoless double-beta decay search. I will alsodiscuss the current status and the future plans of the MAJORANA DEMONSTRATOR,as well as the plans for a future tonne-scale $^{76}$Ge experiment.

Published
2018

35. Initial Results from the Majorana Demonstrator

Author

Caldwell, T. S., Abgrall, N., Alvis, S. I., Arnquist, I. J., Avignone III, F. T., Barabash, A. S., Barton, C. J., Bertrand, F. E., Bode, T., Bos, B., Bradley, A. W., Brudanin, V., Busch, M., Buuck, M., Chan, Y-D., Christofferson, C. D., Chu, P. -H., Cuesta, C., Detwiler, J. A., Dunagan, C., Efremenko, Yu., Ejiri, H., Elliott, S. R., Gilliss, T., Giovanetti, G. K., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Haufe, C. R., Hehn, L., Henning, R., Hoppe, E. W., Howe, M. A., Keeter, K. J., Kidd, M. F., Konovalov, S. I., Kouzes, R. T., Lopez, A. M., Martin, R. D., Massarczyk, R., Meijer, S. J., Mertens, S., Myslik, J., O'Shaughnessy, C., Othman, G., Pettus, W., Poon, A. W. P., Radford, D. C., Rager, J., Reine, A. L., Rielage, K., Robertson, R. G. H., Ruof, N. W., Shanks, B., Shirchenko, M., Suriano, A. M., Tedeschi, D., Trimble, J. E., Varner, R. L., Vasilyev, S., Vetter, K., Vorren, K., White, B. R., Wilkerson, J. F., Wiseman, C., Xu, W., Yakushev, E., Yu, C. -H., Yumatov, V., Zhitnikov, I., and Zhu, B. X.

Subjects
Physics - Instrumentation and Detectors, Nuclear Experiment
Abstract

The MAJORANA Collaboration has assembled an array of high purity Ge detectors to search for neutrinoless double-beta decay in $^{76}$Ge with the goal of establishing the required background and scalability of a Ge-based next-generation ton-scale experiment. The MAJORANA DEMONSTRATOR consists of 44 kg of high-purity Ge (HPGe) detectors (30 kg enriched in $^{76}$Ge) with a low-noise p-type point contact (PPC) geometry. The detectors are split between two modules which are contained in a single lead and high-purity copper shield at the Sanford Underground Research Facility in Lead, South Dakota. Following a commissioning run that started in June 2015, the full detector array has been acquiring data since August 2016. We will discuss the status of the MAJORANA DEMONSTRATOR and initial results from the first physics run; including current background estimates, exotic low-energy physics searches, projections on the physics reach of the DEMONSTRATOR, and implications for a ton-scale Ge-based neutrinoless double-beta decay search., Comment: Proceedings of TAUP 2017: XV International Conference on Topics in Astroparticle and Underground Physics (24-28 July 2017, Sudbury, ON, Canada)

Published
2017

36. Data quality assurance for the MAJORANA DEMONSTRATOR

Author

Myslik, J., Abgrall, N., Alvis, S. I., Arnquist, I. J., Avignone III, F. T., Barabash, A. S., Barton, C. J., Bertrand, F. E., Bode, T., Bradley, A. W., Brudanin, V., Busch, M., Buuck, M., Caldwell, T. S., Chan, Y-D., Christofferson, C. D., Chu, P-H., Cuesta, C., Detwiler, J. A., Dunagan, C., Efremenko, Yu., Ejiri, H., Elliott, S. R., Gilliss, T., Giovanetti, G. K., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Haufe, C. R., Hehn, L., Henning, R., Hoppe, E. W., Howe, M. A., Keeter, K. J., Kidd, M. F., Konovalov, S. I., Kouzes, R. T., Lopez, A. M., Martin, R. D., Massarczyk, R., Meijer, S. J., Mertens, S., O'Shaughnessy, C., Othman, G., Pettus, W., Poon, A. W. P., Radford, D. C., Rager, J., Reine, A. L., Rielage, K., Robertson, R. G. H., Ruof, N. W., Shanks, B., Shirchenko, M., Suriano, A. M., Tedeschi, D., Trimble, J. E., Varner, R. L., Vasilyev, S., Vetter, K., Vorren, K., White, B. R., Wilkerson, J. F., Wiseman, C., Xu, W., Yakushev, E., Yu, C-H., Yumatov, V., Zhitnikov, I., and Zhu, B. X.

Subjects
Physics - Instrumentation and Detectors
Abstract

The MAJORANA DEMONSTRATOR is an experiment constructed to search for neutrinoless double-beta decays in germanium-76 and to demonstrate the feasibility to deploy a large-scale experiment in a phased and modular fashion. It consists of two modular arrays of natural and $^{76}$Ge-enriched germanium detectors totalling 44.1 kg, located at the 4850' level of the Sanford Underground Research Facility in Lead, South Dakota, USA. Any neutrinoless double-beta decay search requires a thorough understanding of the background and the signal energy spectra. The various techniques employed to ensure the integrity of the measured spectra are discussed. Data collection is monitored with a thorough set of checks, and subsequent careful analysis is performed to qualify the data for higher level physics analysis. Instrumental background events are tagged for removal, and problematic channels are removed from consideration as necessary., Comment: 5 pages, 2 figures, Proceedings of TAUP 2017 - XV International Conference on Topics in Astroparticle and Underground Physics (Sudbury ON, Canada, July 24-28, 2017)

Published
2017

37. Contamination Control and Assay Results for the Majorana Demonstrator Ultra Clean Components

Author

Christofferson, C. D., Abgrall, N., Alvis, S. I., Arnquist, I. J., Avignone III, F. T., Barabash, A. S., Barton, C. J., Bertrand, F. E., Bode, T., Bradley, A. W., Brudanin, V., Busch, M., Buuck, M., Caldwell, T. S., Chan, Y-D., Chu, P. -H., Cuesta, C., Detwiler, J. A., Dunagan, C., Efremenko, Yu., Ejiri, H., Elliott, S. R., Gilliss, T., Giovanetti, G. K., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Haufe, C. R., Hehn, L., Henning, R., Hoppe, E. W., Howe, M. A., Keeter, K. J., Kidd, M. F., Konovalov, S. I., Kouzes, R. T., Lopez, A. M., Martin, R. D., Massarczyk, R., Meijer, S. J., Mertens, S., Myslik, J., O'Shaughnessy, C., Othman, G., Poon, A. W. P., Radford, D. C., Rager, J., Reine, A. L., Rielage, K., Robertson, R. G. H., Rouf, N. W., Shanks, B., Shirchenko, M., Suriano, A. M., Tedeschi, D., Trimble, J. E., Varner, R. L., Vasilyev, S., Vetter, K., Vorren, K., White, B. R., Wilkerson, J. F., Wiseman, C., Xu, W., Yakushev, E., Yu, C. -H., Yumatov, V., Zhitnikov, I., and Zhu, B. X.

Subjects
Physics - Instrumentation and Detectors, Nuclear Experiment
Abstract

The MAJORANA DEMONSTRATOR is a neutrinoless double beta decay experiment utilizing enriched Ge-76 detectors in 2 separate modules inside of a common solid shield at the Sanford Underground Research Facility. The DEMONSTRATOR has utilized world leading assay sensitivities to develop clean materials and processes for producing ultra-pure copper and plastic components. This experiment is now operating, and initial data provide new insights into the success of cleaning and processing. Post production copper assays after the completion of Module 1 showed an increase in U and Th contamination in finished parts compared to starting bulk material. A revised cleaning method and additional round of surface contamination studies prior to Module 2 construction have provided evidence that more rigorous process control can reduce surface contamination. This article describes the assay results and discuss further studies to take advantage of assay capabilities for the purpose of maintaining ultra clean fabrication and process design., Comment: Proceedings of Low Radioactivity Techniques (LRT May 2017, Seoul)

Published
2017
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38. Progress Toward A $2\nu\beta\beta$ Measurement For The Majorana Demonstrator

Author

Gilliss, T, Abgrall, N, Alvis, S I, Arnquist, I J, Avignone III, F T, Barabash, A S, Barton, C J, Bertrand, F E, Bode, T, Bradley, A W, Brudanin, V, Busch, M, Buuck, M, Caldwell, T S, Chan, Y-D, Christofferson, C D, Chu, P -H, Cuesta, C, Detwiler, J A, Dunagan, C, Efremenko, Yu, Ejiri, H, Elliott, S R, Giovanetti, G K, Green, M P, Gruszko, J, Guinn, I S, Guiseppe, V E, Haufe, C R, Hehn, L, Henning, R, Hoppe, E W, Howe, M A, Keeter, K J, Kidd, M F, Konovalov, S I, Kouzes, R T, Lopez, A M, Martin, R D, Massarczyk, R, Meijer, S J, Mertens, S, Myslik, J, O'Shaughnessy, C, Othman, G, Pettus, W, Poon, A W P, Radford, D C, Rager, J, Reine, A L, Rielage, K, Robertson, R G H, Ruof, N W, Shanks, B, Shirchenko, M, Suriano, A M, Tedeschi, D, Trimble, J E, Varner, R L, Vasilyev, S, Vetter, K, Vorren, K, White, B R, Wilkerson, J F, Wiseman, C, Xu, W, Yakushev, E, Yu, C -H, Yumatov, V, Zhitnikov, I, and Zhu, B X

Subjects
Physics - Instrumentation and Detectors
Abstract

The MAJORANA DEMONSTRATOR is a $^{76}$Ge-based neutrinoless double-beta decay ($0\nu\beta\beta$) experiment. Staged at the 4850 ft level of the Sanford Underground Research Facility, the DEMONSTRATOR operates an array of high-purity p-type point contact Ge detectors deployed within a graded passive shield and an active muon veto system. The present work concerns the two-neutrino double-beta decay mode ($2\nu\beta\beta$) of $^{76}$Ge. For Ge detectors, having superior energy resolution (0.1%), this mode poses negligible background to the $0\nu\beta\beta$ mode, even for a ton-scale experiment. However, the measurement of the $2\nu\beta\beta$ mode allows for careful systematics checks of active detector mass, enrichment fraction, and pulse shape discrimination cuts related to both the $0\nu\beta\beta$ and $2\nu\beta\beta$ decay modes. A precision measurement of the $2\nu\beta\beta$ shape also allows searches for spectral distortions, possibly indicative of new physics, including $0\nu\beta\beta\chi$. Work is underway to construct a full experimental background model enabling a Bayesian fit to the measured energy spectrum and extraction of a precise $2\nu\beta\beta$ spectrum and half-life., Comment: 5 pages, 2 figures, TAUP 2017: XV International Conference on Topics in Astroparticle and Underground Physics

Published
2017

39. Spectral analysis for the Majorana Demonstrator experiment

Author

Hehn, L., Abgrall, N., Alvis, S. I., Arnquist, I. J., Avignone III, F. T., Barabash, A. S., Barton, C. J., Bertrand, F. E., Bode, T., Bradley, A. W., Brudanin, V., Busch, M., Buuck, M., Caldwell, T. S., Chan, Y-D., Christofferson, C. D., Chu, P-H., Cuesta, C., Detwiler, J. A., Dunagan, C., Efremenko, Yu., Ejiri, H., Elliott, S. R., Gilliss, T., Giovanetti, G. K., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Haufe, C. R., Henning, R., Hoppe, E. W., Howe, M. A., Keeter, K. J., Kidd, M. F., Konovalov, S. I., Kouzes, R. T., Lopez, A. M., Martin, R. D., Massarczyk, R., Meijer, S. J., Mertens, S., Myslik, J., O'Shaughnessy, C., Othman, G., Pettus, W., Poon, A. W. P., Radford, D. C., Rager, J., Reine, A. L., Rielage, K., Robertson, R. G. H., Ruof, N. W., Shanks, B., Shirchenko, M., Suriano, A. M., Tedeschi, D., Trimble, J. E., Varner, R. L., Vasilyev, S., Vetter, K., Vorren, K., White, B. R., Wilkerson, J. F., Wiseman, C., Xu, W., Yakushev, E., Yu, C-H., Yumatov, V., Zhitnikov, I., and Zhu, B. X.

Subjects
Physics - Instrumentation and Detectors, Nuclear Experiment
Abstract

The MAJORANA DEMONSTRATOR is an experiment constructed to search for neutrinoless double-beta decays in germanium-76 and to demonstrate the feasibility to deploy a ton-scale experiment in a phased and modular fashion. It consists of two modular arrays of natural and $^{76}\textrm{Ge}$-enriched germanium detectors totaling 44.1 kg (29.7 kg enriched detectors), located at the 4850' level of the Sanford Underground Research Facility in Lead, South Dakota, USA. Data taken with this setup since summer 2015 at different construction stages of the experiment show a clear reduction of the observed background index around the ROI for $0\nu\beta\beta$-decay search due to improvements in shielding. We discuss the statistical approaches to search for a $0\nu\beta\beta$-signal and derive the physics sensitivity for an expected exposure of $10\,\textrm{kg}{\cdot}\textrm{y}$ from enriched detectors using a profile likelihood based hypothesis test in combination with toy Monte Carlo data., Comment: 5 page, 2 figures, to appear in Proceedings of TAUP 2017 - XV International Conference on Topics in Astroparticle and Underground Physics, 24 - 28 July 2017, Sudbury, ON, Canada

Published
2017

40. Search for Zero-Neutrino Double Beta Decay in 76Ge with the Majorana Demonstrator

Author

Aalseth, C. E., Abgrall, N., Aguayo, E., Alvis, S. I., Amman, M., Arnquist, I. J., Avignone III, F. T., Back, H. O., Barabash, A. S., Barbeau, P. S., Barton, C. J., Barton, P. J., Bertrand, F. E., Bode, T., Bos, B., Boswell, M., Brodzinski, R. L., Bradley, A. W., Brudanin, V., Busch, M., Buuck, M., Caldwell, A. S., Caldwell, T. S., Chan, Y-D., Christofferson, C. D., Chu, P. -H., Collar, J. I., Combs, D. C., Cooper, R. J., Cuesta, C., Detwiler, J. A., Doe, P. J., Dunmore, J. A., Efremenko, Yu., Ejiri, H., Elliott, S. R., Fast, J. E., Finnerty, P., Fraenkle, F. M., Fu, Z., Fujikawa, B. K., Fuller, E., Galindo-Uribarri, A., Gehman, V. M., Gilliss, T., Giovanetti, G. K., Goett, J., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Hallin, A. L., Haufe, C. R., Hehn, L., Henning, R., Hoppe, E. W., Hossbach, T. W., Howe, M. A., Jasinski, B. R., Johnson, R. A., Keeter, K. J., Kephart, J. D., Kidd, M. F., Knecht, A., Konovalov, S. I., Kouzes, R. T., Lesko, K. T., LaFerriere, B. D., Leon, J., Leviner, L. E., Loach, J. C., Lopez, A. M., Luke, P. N., MacMullin, J., MacMullin, S., Marino, M. G., Martin, R. D., Massarczyk, R., McDonald, A. B., Mei, D. -M., Meijer, S. J., Merriman, J. H., Mertens, S., Miley, H. S., Miller, M. L., Myslik, J., Orrell, J. L., O'Shaughnessy, C., Othman, G., Overman, N. R., Pettus, W., Phillips II, D. G., Poon, A. W. P., Perumpilly, G., Pushkin, K., Radford, D. C., Rager, J., Reeves, J. H., Reine, A. L., Rielage, K., Robertson, R. G. H., Ronquest, M. C., Ruof, N. W., Schubert, A. G., Shanks, B., Shirchenko, M., Snavely, K. J., Snyder, N., Steele, D., Suriano, A. M., Tedeschi, D., Tornow, W., Trimble, J. E., Varner, R. L., Vasilyev, S., Vetter, K., Vorren, K., White, B. R., Wilkerson, J. F., Wiseman, C., Xu, W., Yakushev, E., Yaver, H., Young, A. R., Yu, C. -H., Yumatov, V., Zhitnikov, I., Zhu, B. X., and Zimmermann, S.

Subjects
Nuclear Experiment, Physics - Instrumentation and Detectors
Abstract

The \MJ\ Collaboration is operating an array of high purity Ge detectors to search for neutrinoless double-beta decay in $^{76}$Ge. The \MJ\ \DEM\ comprises 44.1~kg of Ge detectors (29.7 kg enriched in $^{76}$Ge) split between two modules contained in a low background shield at the Sanford Underground Research Facility in Lead, South Dakota. Here we present results from data taken during construction, commissioning, and the start of full operations. We achieve unprecedented energy resolution of 2.5 keV FWHM at \qval\ and a very low background with no observed candidate events in 10 kg yr of enriched Ge exposure, resulting in a lower limit on the half-life of $1.9\times10^{25}$ yr (90\% CL). This result constrains the effective Majorana neutrino mass to below 240 to 520 meV, depending on the matrix elements used. In our experimental configuration with the lowest background, the background is $4.0_{-2.5}^{+3.1}$ counts/(FWHM t yr)., Comment: typos fixed

Published
2017
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41. The Large Enriched Germanium Experiment for Neutrinoless Double Beta Decay (LEGEND)

Author

LEGEND Collaboration, Abgrall, N., Abramov, A., Abrosimov, N., Abt, I., Agostini, M., Agartioglu, M., Ajjaq, A., Alvis, S. I., Avignone III, F. T., Bai, X., Balata, M., Barabanov, I., Barabash, A. S., Barton, P. J., Baudis, L., Bezrukov, L., Bode, T., Bolozdynya, A., Borowicz, D., Boston, A., Boston, H., Boyd, S. T. P., Breier, R., Brudanin, V., Brugnera, R., Busch, M., Buuck, M., Caldwell, A., Caldwell, T. S., Camellato, T., Carpenter, M., Cattadori, C., Cederkäll, J., Chan, Y. -D., Chen, S., Chernogorov, A., Christofferson, C. D., Chu, P. -H., Cooper, R. J., Cuesta, C., Demidova, E. V., Deng, Z., Deniz, M., Detwiler, J. A., Di Marco, N., Domula, A., Du, Q., Efremenko, Yu., Egorov, V., Elliott, S. R., Fields, D., Fischer, F., Galindo-Uribarri, A., Gangapshev, A., Garfagnini, A., Gilliss, T., Giordano, M., Giovanetti, G. K., Gold, M., Golubev, P., Gooch, C., Grabmayr, P., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Gurentsov, V., Gurov, Y., Gusev, K., Hakenmüeller, J., Harkness-Brennan, L., Harvey, Z. R., Haufe, C. R., Hauertmann, L., Heglund, D., Hehn, L., Heinz, A., Hiller, R., Hinton, J., Hodak, R., Hofmann, W., Howard, S., Howe, M. A., Hult, M., Inzhechik, L. V., Csáthy, J. Janicskó, Janssens, R., Ješkovský, M., Jochum, J., Johansson, H. T., Judson, D., Junker, M., Kaizer, J., Kang, K., Kazalov, V., Kermaïdic, Y., Kiessling, F., Kirsch, A., Kish, A., Klimenko, A., Knöpfle, K. T. K. T., Kochetov, O., Konovalov, S. I., Kontul, I., Kornoukhov, V. N., Kraetzschmar, T., Kröninger, K., Kumar, A., Kuzminov, V. V., Lang, K., Laubenstein, M., Lazzaro, A., Li, Y. L., Li, Y. -Y., Li, H. B., Lin, S. T., Lindner, M., Lippi, I., Liu, S. K., Liu, X., Liu, J., Loomba, D., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Ma, H., Majorovits, B., Mamedov, F., Martin, R. D., Massarczyk, R., Matthews, J. A. J., McFadden, N., Mei, D. -M., Mei, H., Meijer, S. J., Mengoni, D., Mertens, S., Miller, W., Miloradovic, M., Mingazheva, R., Misiaszek, M., Moseev, P., Myslik, J., Nemchenok, I., Nilsson, T., Nolan, P., O'Shaughnessy, C., Othman, G., Panas, K., Pandola, L., Papp, L., Pelczar, K., Peterson, D., Pettus, W., Poon, A. W. P., Povinec, P. P., Pullia, A., Quintana, X. C., Radford, D. C., Rager, J., Ransom, C., Recchia, F., Reine, A. L., Riboldi, S., Rielage, K., Rozov, S., Rouf, N. W., Rukhadze, E., Rumyantseva, N., Saakyan, R., Sala, E., Salamida, F., Sandukovsky, V., Savard, G., Schönert, S., Schütz, A. -K., Schulz, O., Schuster, M., Schwingenheuer, B., Selivanenko, O., Sevda, B., Shanks, B., Shevchik, E., Shirchenko, M., Simkovic, F., Singh, L., Singh, V., Skorokhvatov, M., Smolek, K., Smolnikov, A., Sonay, A., Spavorova, M., Stekl, I., Stukov, D., Tedeschi, D., Thompson, J., Van Wechel, T., Varner, R. L., Vasenko, A. A., Vasilyev, S., Veresnikova, A., Vetter, K., von Sturm, K., Vorren, K., Wagner, M., Wang, G. -J., Waters, D., Wei, W. -Z., Wester, T., White, B. R., Wiesinger, C., Wilkerson, J. F., Willers, M., Wiseman, C., Wojcik, M., Wong, H. T., Wyenberg, J., Xu, W., Yakushev, E., Yang, G., Yu, C. -H., Yue, Q., Yumatov, V., Zeman, J., Zeng, Z., Zhitnikov, I., Zhu, B., Zinatulina, D., Zschocke, A., Zsigmond, A. J., Zuber, K., and Zuzel, G.

Subjects
Physics - Instrumentation and Detectors, High Energy Physics - Experiment, Nuclear Experiment
Abstract

The observation of neutrinoless double-beta decay (0${\nu}{\beta}{\beta}$) would show that lepton number is violated, reveal that neutrinos are Majorana particles, and provide information on neutrino mass. A discovery-capable experiment covering the inverted ordering region, with effective Majorana neutrino masses of 15 - 50 meV, will require a tonne-scale experiment with excellent energy resolution and extremely low backgrounds, at the level of $\sim$0.1 count /(FWHM$\cdot$t$\cdot$yr) in the region of the signal. The current generation $^{76}$Ge experiments GERDA and the MAJORANA DEMONSTRATOR utilizing high purity Germanium detectors with an intrinsic energy resolution of 0.12%, have achieved the lowest backgrounds by over an order of magnitude in the 0${\nu}{\beta}{\beta}$ signal region of all 0${\nu}{\beta}{\beta}$ experiments. Building on this success, the LEGEND collaboration has been formed to pursue a tonne-scale $^{76}$Ge experiment. The collaboration aims to develop a phased 0${\nu}{\beta}{\beta}$ experimental program with discovery potential at a half-life approaching or at $10^{28}$ years, using existing resources as appropriate to expedite physics results., Comment: Proceedings of the MEDEX'17 meeting (Prague, May 29 - June 2, 2017)

Published
2017
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42. The Status and Initial Results of the MAJORANA DEMONSTRATOR Experiment

Author

Guiseppe, V. E., Abgrall, N., Alvis, S. I., Arnquist, I. J., Avignone III, F. T., Barabash, A. S., Barton, C. J., Bertrand, F. E., Bode, T., Bradley, A. W., Brudanin, V., Busch, M., Buuck, M., Caldwell, T. S., Chan, Y-D., Christofferson, C. D., Chu, P. -H., Cuesta, C., Detwiler, J. A., Dunagan, C., Efremenko, Yu., Ejiri, H., Elliott, S. R., Gilliss, T., Giovanetti, G. K., Green, M. P., Gruszko, J., Guinn, I. S., Haufe, C. R., Hehn, L., Henning, R., Hoppe, E. W., Howe, M. A., Keeter, K. J., Kidd, M. F., Konovalov, S. I., Kouzes, R. T., Lopez, A. M., Martin, R. D., Massarczyk, R., Meijer, S. J., Mertens, S., Myslik, J., O'Shaughnessy, C., Othman, G., Poon, A. W. P., Radford, D. C., Rager, J., Reine, A. L., Rielage, K., Robertson, R. G. H., Rouf, N. W., Shanks, B., Shirchenko, M., Suriano, A. M., Tedeschi, D., Trimble, J. E., Varner, R. L., Vasilyev, S., Vetter, K., Vorren, K., White, B. R., Wilkerson, J. F., Wiseman, C., Xu, W., Yakushev, E., Yu, C. -H., Yumatov, V., Zhitnikov, I., and Zhu, B. X.

Subjects
Physics - Instrumentation and Detectors, Nuclear Experiment
Abstract

Neutrinoless double-beta decay searches play a major role in determining the nature of neutrinos, the existence of a lepton violating process, and the effective Majorana neutrino mass. The MAJORANA Collaboration assembled an array of high purity Ge detectors to search for neutrinoless double-beta decay in Ge-76. The MAJORANA DEMONSTRATOR is comprised of 44.1 kg (29.7 kg enriched in Ge-76) of Ge detectors divided between two modules contained in a low-background shield at the Sanford Underground Research Facility in Lead, South Dakota, USA. The initial goals of the DEMONSTRATOR are to establish the required background and scalability of a Ge-based next-generation ton-scale experiment. Following a commissioning run that started in 2015, the first detector module started low-background data production in early 2016. The second detector module was added in August 2016 to begin operation of the entire array. We discuss results of the initial physics runs, as well as the status and physics reach of the full MAJORANA DEMONSTRATOR experiment., Comment: Proceedings of the MEDEX'17 meeting (Prague, May 29 - June 2, 2017)

Published
2017
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43. The Processing of Enriched Germanium for the MAJORANA DEMONSTRATOR and R&D for a Possible Future Ton-Scale Ge-76 Double-Beta Decay Experiment

Author

Abgrall, N., Arnquist, I. J., Avignone III, F. T., Barabash, A. S., Bertrand, F. E., Bradley, A. W., Brudanin, V., Busch, M., Buuck, M., Caja, J., Caja, M., Caldwell, T. S., Christofferson, C. D., Chu, P. -H., Cuesta, C., Detwiler, J. A., Dunagan, C., Dunstan, D. T., Efremenko, Yu., Ejiri, H., Elliott, S. R., Gilliss, T., Giovanetti, G. K., Goett, J., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Haufe, C. R. S., Henning, R., Hoppe, E. W., Jasinski, B. R., Kidd, M. F., Konovalov, S. I., Kouzes, R. T., Lopez, A. M., MacMullin, J., Martin, R. D., Massarczyk, R., Meijer, S. J., Mertens, S., Meyer, J. H., Myslik, J., O'Shaughnessy, C., Poon, A. W. P., Radford, D. C., Rager, J., Reine, A. L., Reising, J. A., Rielage, K., Robertson, R. G. H., Shanks, B., Shirchenko, M., Suriano, A. M., Tedeschi, D., Toth, L. M., Trimble, J. E., Varner, R. L., Vasilyev, S., Vetter, K., Vorren, K., White, B. R., Wilkerson, J. F., Wiseman, C., Xu, W., Yakushev, E., Yu, C. -H., Yumatov, V., Zhitnikov, I., and Zhu, B. X.

Subjects
Physics - Instrumentation and Detectors, Nuclear Experiment
Abstract

The MAJORANA DEMONSTRATOR is an array of point-contact Ge detectors fabricated from Ge isotopically enriched to 88% in Ge-76 to search for neutrinoless double beta decay. The processing of Ge for germanium detectors is a well-known technology. However, because of the high cost of Ge enriched in Ge-76, special procedures were required to maximize the yield of detector mass and to minimize exposure to cosmic rays. These procedures include careful accounting for the material; shielding it to reduce cosmogenic generation of radioactive isotopes; and development of special reprocessing techniques for contaminated solid germanium, shavings, grindings, acid etchant and cutting fluids from detector fabrication. Processing procedures were developed that resulted in a total yield in detector mass of 70%. However, none of the acid-etch solution and only 50% of the cutting fluids from detector fabrication were reprocessed. Had they been processed, the projections for the recovery yield would be between 80 -- 85%. Maximizing yield is critical to justify a possible future ton-scale experiment. A process for recovery of germanium from the acid-etch solution was developed with yield of about 90%. All material was shielded or stored underground whenever possible to minimize the formation of Ge-68 by cosmic rays, which contributes background in the double-beta decay region of interest and cannot be removed by zone refinement and crystal growth. Formation of Ge-68 was reduced by a significant factor over that in natural abundance detectors not protected from cosmic rays., Comment: Submitted to NIM-A

Published
2017
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44. The Majorana Demonstrator calibration system

Author

Abgrall, N., Arnquist, I. J., Avignone III, F. T., Barabash, A. S., Bertrand, F. E., Boswell, M., Bradley, A. W., Brudanin, V., Busch, M., Buuck, M., Caldwell, T. S., Christofferson, C. D., Chu, P. -H., Cuesta, C., Detwiler, J. A., Dunagan, C., Efremenko, Yu., Ejiri, H., Elliott, S. R., Fu, Z., Gehman, V. M., Gilliss, T., Giovanetti, G. K., Goett, J., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Haufe, C. R., Henning, R., Hoppe, E. W., Howe, M. A., Jasinski, B. R., Keeter, K. J., Kidd, M. F., Konovalov, S. I., Kouzes, R. T., Lopez, A. M., MacMullin, J., Martin, R. D., Meijer, R. Massarczyk S. J., Mertens, S., Orrell, J. L., O'Shaughnessy, C., Poon, A. W. P., Radford, D. C., Rager, J., Reine, A. L., Rielage, K., Robertson, R. G. H., Shanks, B., Shirchenko, M., Suriano, A. M., Tedeschi, D., Trimble, J. E., Varner, R. L., Vasilyev, S., Vetter, K., Vorren, K., White, B. R., Wilkerson, J. F., Wiseman, C., Xu, W., Yu, C. -H., Yumatov, V., Zhitnikov, I., and Zhu, B. X.

Subjects
Physics - Instrumentation and Detectors, Nuclear Experiment
Abstract

The MAJORANA Collaboration is searching for the neutrinoless double-beta decay of the nucleus $^{76}$Ge. The MAJORANA DEMONSTRATOR is an array of germanium detectors deployed with the aim of implementing background reduction techniques suitable for a 1-tonne $^{76}$Ge-based search. The ultra low-background conditions require regular calibrations to verify proper function of the detectors. Radioactive line sources can be deployed around the cryostats containing the detectors for regular energy calibrations. When measuring in low-background mode, these line sources have to be stored outside the shielding so they do not contribute to the background. The deployment and the retraction of the source are designed to be controlled by the data acquisition system and do not require any direct human interaction. In this paper, we detail the design requirements and implementation of the calibration apparatus, which provides the event rates needed to define the pulse-shape cuts and energy calibration used in the final analysis as well as data that can be compared to simulations.

Published
2017
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45. New limits on Bosonic Dark Matter, Solar Axions, Pauli Exclusion Principle Violation, and Electron Decay from the Majorana Demonstrator

Author

Abgrall, N., Arnquist, I. J., Avignone III, F. T., Barabash, A. S., Bertrand, F. E., Bradley, A. W., Brudanin, V., Busch, M., Buuck, M., Caldwell, T. S., Chan, Y-D., Christofferson, C. D., Chu, P. -H., Cuesta, C., Detwiler, J. A., Dunagan, C., Efremenko, Yu., Ejiri, H., Elliott, S. R., Gilliss, T., Giovanetti, G. K., Goett, J., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Haufe, C. R. S., Henning, R., Hoppe, E. W., Howard, S., Howe, M. A., Jasinski, B. R., Keeter, K. J., Kidd, M. F., Konovalov, S. I., Kouzes, R. T., Lopez, A. M., MacMullin, J., Martin, R. D., Massarczyk, R., Meijer, S. J., Mertens, S., O'Shaughnessy, C., Poon, A. W. P., Radford, D. C., Rager, J., Reine, A. L., Rielage, K., Robertson, R. G. H., Shanks, B., Shirchenko, M., Suriano, A. M., Tedeschi, D., Trimble, J. E., Varner, R. L., Vasilyev, S., Vetter, K., Vorren, K., White, B. R., Wilkerson, J. F., Wiseman, C., Xu, W., Yakushev, E., Yu, C. -H., Yumatov, V., Zhitnikov, I., and Zhu, B. X.

Subjects
Nuclear Experiment, Physics - Instrumentation and Detectors
Abstract

We present new limits on exotic keV-scale physics based on 478 kg d of MAJORANA DEMONSTRATOR commissioning data. Constraints at the 90% confidence level are derived on bosonic dark matter (DM) and solar axion couplings, Pauli exclusion principle violating (PEPV) decay, and electron decay using monoenergetic peak signal-limits above our background. Our most stringent DM constraints are set for 11.8 keV mass particles, limiting $g_{Ae} <4.5\times 10^{-13}$ for pseudoscalars and $\frac{\alpha'}{\alpha} < 9.7\times 10^{-28}$ for vectors. We also report a 14.4 keV solar axion coupling limit of $g_{AN}^{\mathrm{eff}}\times g_{Ae}~<~3.8 \times 10^{-17}$, a $\frac{1}{2}\beta^2~<~8.5\times10^{-48}$ limit on the strength of PEPV electron transitions, and a lower limit on the electron lifetime of $\tau_e > 1.2 \times 10^{24}\;$yr for $e^- \rightarrow$ invisible.

Published
2016
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46. First Limit on the Direct Detection of Lightly Ionizing Particles for Electric Charge as Low as e/1000 with the Majorana Demonstrator

Author

Alvis, SI, Arnquist, IJ, Avignone, FT, Barabash, AS, Barton, CJ, Bertrand, FE, Brudanin, V, Busch, M, Buuck, M, Caldwell, TS, Chan, Y-D, Christofferson, CD, Chu, P-H, Cuesta, C, Detwiler, JA, Dunagan, C, Efremenko, Yu, Ejiri, H, Elliott, SR, Gilliss, T, Giovanetti, GK, Green, MP, Gruszko, J, Guinn, IS, Guiseppe, VE, Haufe, CR, Hehn, L, Henning, R, Hoppe, EW, Howe, MA, Konovalov, SI, Kouzes, RT, Lopez, AM, Martin, RD, Massarczyk, R, Meijer, SJ, Mertens, S, Myslik, J, O'Shaughnessy, C, Othman, G, Pettus, W, Poon, AWP, Radford, DC, Rager, J, Reine, AL, Rielage, K, Robertson, RGH, Ruof, NW, Shanks, B, Shirchenko, M, Suriano, AM, Tedeschi, D, Varner, RL, Vasilyev, S, Vorren, K, White, BR, Wilkerson, JF, Wiseman, C, Xu, W, Yakushev, E, Yu, C-H, Yumatov, V, Zhitnikov, I, and Zhu, BX

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Majorana Collaboration, hep-ex, astro-ph.CO, physics.ins-det, Mathematical Sciences, Engineering, General Physics, Mathematical sciences, Physical sciences
Abstract

The Majorana Demonstrator is an ultralow-background experiment searching for neutrinoless double-beta decay in ^{76}Ge. The heavily shielded array of germanium detectors, placed nearly a mile underground at the Sanford Underground Research Facility in Lead, South Dakota, also allows searches for new exotic physics. Free, relativistic, lightly ionizing particles with an electrical charge less than e are forbidden by the standard model but predicted by some of its extensions. If such particles exist, they might be detected in the Majorana Demonstrator by searching for multiple-detector events with individual-detector energy depositions down to 1 keV. This search is background-free, and no candidate events have been found in 285 days of data taking. New direct-detection limits are set for the flux of lightly ionizing particles for charges as low as e/1000.

Published
2018

47. The Majorana Demonstrator Status and Preliminary Results

Author

Yu, CH, Alvis, SI, Arnquist, IJ, Avignone, FT, Barabash, AS, Barton, CJ, Bertrand, FE, Bode, T, Brudanin, V, Busch, M, Buuck, M, Caldwell, TS, Chan, YD, Christofferson, CD, Chu, PH, Cuesta, C, Detwiler, JA, Dunagan, C, Efremenko, Y, Ejiri, H, Elliott, SR, Gilliss, T, Giovanetti, GK, Green, M, Gruszko, J, Guinn, IS, Guiseppe, VE, Haufe, CR, Hehn, L, Henning, R, Hoppe, EW, Howe, MA, Keeter, KJ, Kidd, MF, Konovalov, SI, Kouzes, RT, Lopez, AM, Martin, RD, Massarczyk, R, Meijer, SJ, Mertens, S, Myslik, J, Othman, G, Pettus, W, Poon, AWP, Radford, DC, Rager, J, Reine, AL, Rielage, K, Ruof, NW, Shanks, B, Shirchenko, M, Suriano, AM, Tedeschi, D, Varner, RL, Vasilyev, S, Vetter, K, Vorren, K, White, BR, Wilkerson, JF, Wiseman, C, Xu, W, Yakushev, E, Yumatov, V, Zhitnikov, I, and Zhu, BZ

Subjects
nucl-ex, physics.ins-det
Abstract

The Majorana Collaboration is using an array of high-purity Ge detectors to search for neutrinoless double-beta decay in 76Ge. Searches for neutrinoless double-beta decay are understood to be the only viable experimental method for testing the Majorana nature of the neutrino. Observation of this decay would imply violation of lepton number, that neutrinos are Majorana in nature, and provide information on the neutrino mass. The Majorana Demonstrator comprises 44.1 kg of p-type point-contact Ge detectors (29.7 kg enriched in 76Ge) surrounded by a low-background shield system. The experiment achieved a high efficiency of converting raw Ge material to detectors and an unprecedented detector energy resolution of 2.5 keV FWHM at Qββ. The Majorana collaboration began taking physics data in 2016. This paper summarizes key construction aspects of the Demonstrator and shows preliminary results from initial data.

Published
2018

48. Search for Neutrinoless Double-β Decay in Ge76 with the Majorana Demonstrator

Author

Aalseth, CE, Abgrall, N, Aguayo, E, Alvis, SI, Amman, M, Arnquist, IJ, Avignone, FT, Back, HO, Barabash, AS, Barbeau, PS, Barton, CJ, Barton, PJ, Bertrand, FE, Bode, T, Bos, B, Boswell, M, Bradley, AW, Brodzinski, RL, Brudanin, V, Busch, M, Buuck, M, Caldwell, AS, Caldwell, TS, Chan, Y-D, Christofferson, CD, Chu, P-H, Collar, JI, Combs, DC, Cooper, RJ, Cuesta, C, Detwiler, JA, Doe, PJ, Dunmore, JA, Efremenko, Yu, Ejiri, H, Elliott, SR, Fast, JE, Finnerty, P, Fraenkle, FM, Fu, Z, Fujikawa, BK, Fuller, E, Galindo-Uribarri, A, Gehman, VM, Gilliss, T, Giovanetti, GK, Goett, J, Green, MP, Gruszko, J, Guinn, IS, Guiseppe, VE, Hallin, AL, Haufe, CR, Hehn, L, Henning, R, Hoppe, EW, Hossbach, TW, Howe, MA, Jasinski, BR, Johnson, RA, Keeter, KJ, Kephart, JD, Kidd, MF, Knecht, A, Konovalov, SI, Kouzes, RT, LaFerriere, BD, Leon, J, Lesko, KT, Leviner, LE, Loach, JC, Lopez, AM, Luke, PN, MacMullin, J, MacMullin, S, Marino, MG, Martin, RD, Massarczyk, R, McDonald, AB, Mei, D-M, Meijer, SJ, Merriman, JH, Mertens, S, Miley, HS, Miller, ML, Myslik, J, Orrell, JL, O'Shaughnessy, C, Othman, G, Overman, NR, Perumpilly, G, Pettus, W, Phillips, DG, Poon, AWP, Pushkin, K, Radford, DC, Rager, J, Reeves, JH, Reine, AL, and Rielage, K

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Synchrotrons and Accelerators, Physical Sciences, Majorana Collaboration, nucl-ex, physics.ins-det, Mathematical Sciences, Engineering, General Physics, Mathematical sciences, Physical sciences
Abstract

The Majorana Collaboration is operating an array of high purity Ge detectors to search for neutrinoless double-β decay in ^{76}Ge. The Majorana Demonstrator comprises 44.1 kg of Ge detectors (29.7 kg enriched in ^{76}Ge) split between two modules contained in a low background shield at the Sanford Underground Research Facility in Lead, South Dakota. Here we present results from data taken during construction, commissioning, and the start of full operations. We achieve unprecedented energy resolution of 2.5 keV FWHM at Q_{ββ} and a very low background with no observed candidate events in 9.95 kg yr of enriched Ge exposure, resulting in a lower limit on the half-life of 1.9×10^{25}  yr (90% C.L.). This result constrains the effective Majorana neutrino mass to below 240-520 meV, depending on the matrix elements used. In our experimental configuration with the lowest background, the background is 4.0_{-2.5}^{+3.1}  counts/(FWHM t yr).

Published
2018

49. Search for Neutrinoless Double-β Decay in ^{76}Ge with the Majorana Demonstrator.

Author

Aalseth, CE, Abgrall, N, Aguayo, E, Alvis, SI, Amman, M, Arnquist, IJ, Avignone, FT, Back, HO, Barabash, AS, Barbeau, PS, Barton, CJ, Barton, PJ, Bertrand, FE, Bode, T, Bos, B, Boswell, M, Bradley, AW, Brodzinski, RL, Brudanin, V, Busch, M, Buuck, M, Caldwell, AS, Caldwell, TS, Chan, Y-D, Christofferson, CD, Chu, P-H, Collar, JI, Combs, DC, Cooper, RJ, Cuesta, C, Detwiler, JA, Doe, PJ, Dunmore, JA, Efremenko, Yu, Ejiri, H, Elliott, SR, Fast, JE, Finnerty, P, Fraenkle, FM, Fu, Z, Fujikawa, BK, Fuller, E, Galindo-Uribarri, A, Gehman, VM, Gilliss, T, Giovanetti, GK, Goett, J, Green, MP, Gruszko, J, Guinn, IS, Guiseppe, VE, Hallin, AL, Haufe, CR, Hehn, L, Henning, R, Hoppe, EW, Hossbach, TW, Howe, MA, Jasinski, BR, Johnson, RA, Keeter, KJ, Kephart, JD, Kidd, MF, Knecht, A, Konovalov, SI, Kouzes, RT, LaFerriere, BD, Leon, J, Lesko, KT, Leviner, LE, Loach, JC, Lopez, AM, Luke, PN, MacMullin, J, MacMullin, S, Marino, MG, Martin, RD, Massarczyk, R, McDonald, AB, Mei, D-M, Meijer, SJ, Merriman, JH, Mertens, S, Miley, HS, Miller, ML, Myslik, J, Orrell, JL, O'Shaughnessy, C, Othman, G, Overman, NR, Perumpilly, G, Pettus, W, Phillips, DG, Poon, AWP, Pushkin, K, Radford, DC, Rager, J, Reeves, JH, Reine, AL, and Rielage, K

Subjects
Majorana Collaboration, nucl-ex, physics.ins-det, General Physics, Mathematical Sciences, Physical Sciences, Engineering
Abstract

The Majorana Collaboration is operating an array of high purity Ge detectors to search for neutrinoless double-β decay in ^{76}Ge. The Majorana Demonstrator comprises 44.1 kg of Ge detectors (29.7 kg enriched in ^{76}Ge) split between two modules contained in a low background shield at the Sanford Underground Research Facility in Lead, South Dakota. Here we present results from data taken during construction, commissioning, and the start of full operations. We achieve unprecedented energy resolution of 2.5 keV FWHM at Q_{ββ} and a very low background with no observed candidate events in 9.95 kg yr of enriched Ge exposure, resulting in a lower limit on the half-life of 1.9×10^{25}  yr (90% C.L.). This result constrains the effective Majorana neutrino mass to below 240-520 meV, depending on the matrix elements used. In our experimental configuration with the lowest background, the background is 4.0_{-2.5}^{+3.1}  counts/(FWHM t yr).

Published
2018

50. Contamination control and assay results for the Majorana Demonstrator ultra clean components

Author

Christofferson, CD, Abgrall, N, Alvis, SI, Arnquist, IJ, Avignone, FT, Barabash, AS, Barton, CJ, Bertrand, FE, Bode, T, Bradley, AW, Brudanin, V, Busch, M, Buuck, M, Caldwell, TS, Chan, Y-D, Chu, P-H, Cuesta, C, Detwiler, JA, Dunagan, C, Efremenko, Yu, Ejiri, H, Elliott, SR, Gilliss, T, Giovanetti, GK, Green, MP, Gruszko, J, Guinn, IS, Guiseppe, VE, Haufe, CR, Hehn, L, Henning, R, Hoppe, EW, Howe, MA, Keeter, KJ, Kidd, MF, Konovalov, SI, Kouzes, RT, Lopez, AM, Martin, RD, Massarczyk, R, Meijer, SJ, Mertens, S, Myslik, J, O’Shaughnessy, C, Othman, G, Poon, AWP, Radford, DC, Rager, J, Reine, AL, Rielage, K, Robertson, RGH, Rouf, NW, Shanks, B, Shirchenko, M, Suriano, AM, Tedeschi, D, Trimble, JE, Varner, RL, Vasilyev, S, Vetter, K, Vorren, K, White, BR, Wilkerson, JF, Wiseman, C, Xu, W, Yakushev, E, Yu, C-H, Yumatov, V, Zhitnikov, I, and Zhu, BX

Subjects
Nuclear and Plasma Physics, Physical Sciences, physics.ins-det, nucl-ex
Abstract

The Majorana Demonstrator is a neutrinoless double beta decay experiment utilizing enriched Ge-76 detectors in 2 separate modules inside of a common solid shield at the Sanford Underground Research Facility. The Demonstrator has utilized world leading assay sensitivities to develop clean materials and processes for producing ultra-pure copper and plastic components. This experiment is now operating, and initial data provide new insights into the success of cleaning and processing. Post production copper assays after the completion of Module 1 showed an increase in U and Th contamination in finished parts compared to starting bulk material. A revised cleaning method and additional round of surface contamination studies prior to Module 2 construction have provided evidence that more rigorous process control can reduce surface contamination. This article describes the assay results and discuss further studies to take advantage of assay capabilities for the purpose of maintaining ultra clean fabrication and process design.

Published
2018

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