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1. An assay-based background projection for the MAJORANA DEMONSTRATOR using Monte Carlo Uncertainty Propagation

Author: Arnquist, I. J., Avignone III, F. T., Barabash, A. S., Barton, C. J., Bhimani, K. H., Blalock, E., Bos, B., Busch, M., Caldwell, T. S., Chan, Y. -D., Christofferson, C. D., Chu, P. -H., Clark, M. L., Cuesta, C., Detwiler, J. A., Efremenko, Yu., Ejiri, H., Elliott, S. R., Fuad, N., Giovanetti, G. K., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Haufe, C. R., Henning, R., Aguilar, D. Hervas, Hoppe, E. W., Hostiuc, A., Kidd, M. F., Kim, I., Kouzes, R. T., Lannen V, T. E., Li, A., López-Castaño, J. M., Martin, R. D., Massarczyk, R., Meijer, S. J., Oli, T. K., Paudel, L. S., Pettus, W., Poon, A. W. P., Radford, D. C., Reine, A. L., Rielage, K., Ruof, N. W., Schaper, D. C., Schleich, S. J., Tedeschi, D., Varner, R. L., Vasilyev, S., Watkins, S. L., Wilkerson, J. F., Wiseman, C., Xu, W., and Yu, C. -H.
Subjects: Nuclear Experiment, Physics - Instrumentation and Detectors
Abstract: The background index is an important quantity which is used in projecting and calculating the half-life sensitivity of neutrinoless double-beta decay ($0\nu\beta\beta$) experiments. A novel analysis framework is presented to calculate the background index using the specific activities, masses and simulated efficiencies of an experiment's components as distributions. This Bayesian framework includes a unified approach to combine specific activities from assay. Monte Carlo uncertainty propagation is used to build a background index distribution from the specific activity, mass and efficiency distributions. This analysis method is applied to the MAJORANA DEMONSTRATOR, which deployed arrays of high-purity Ge detectors enriched in $^{76}$Ge to search for $0\nu\beta\beta$. The framework projects a mean background index of $\left[8.95 \pm 0.36\right] \times 10^{-4}$cts/(keV kg yr) from $^{232}$Th and $^{238}$U in the DEMONSTRATOR's components., Comment: 9 pages, 3 figures
Published: 2024

2. Majorana Demonstrator Data Release for AI/ML Applications

Author: Arnquist, I. J., Avignone III, F. T., Barabash, A. S., Barton, C. J., Bhimani, K. H., Blalock, E., Bos, B., Busch, M., Buuck, M., Caldwell, T. S., Chan, Y. -D., Christofferson, C. D., Chu, P. -H., Clark, M. L., Cuesta, C., Detwiler, J. A., Efremenko, Yu., Ejiri, H., Elliott, S. R., Fuad, N., Giovanetti, G. K., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Haufe, C. R., Henning, R., Aguilar, D. Hervas, Hoppe, E. W., Hostiuc, A., Kidd, M. F., Kim, I., Kouzes, R. T., Lannen V, T. E., Li, A., Lopez-Castano, J. M., Martin, R. D., Massarczyk, R., Meijer, S. J., Mertens, S., Oli, T. K., Paudel, L. S., Pettus, W., Poon, A. W. P., Quenallata, B., Radford, D. C., Reine, A. L., Rielage, K., Ruof, N. W., Schaper, D. C., Schleich, S. J., Tedeschi, D., Varner, R. L., Vasilyev, S., Watkins, S. L., Wilkerson, J. F., Wiseman, C., Xu, W., Yu, C. -H., and Zhu, B. X.
Subjects: Computer Science - Machine Learning, Nuclear Experiment, Physics - Data Analysis, Statistics and Probability, Physics - Instrumentation and Detectors
Abstract: The enclosed data release consists of a subset of the calibration data from the Majorana Demonstrator experiment. Each Majorana event is accompanied by raw Germanium detector waveforms, pulse shape discrimination cuts, and calibrated final energies, all shared in an HDF5 file format along with relevant metadata. This release is specifically designed to support the training and testing of Artificial Intelligence (AI) and Machine Learning (ML) algorithms upon our data. This document is structured as follows. Section I provides an overview of the dataset's content and format; Section II outlines the location of this dataset and the method for accessing it; Section III presents the NPML Machine Learning Challenge associated with this dataset; Section IV contains a disclaimer from the Majorana collaboration regarding the use of this dataset; Appendix A contains technical details of this data release. Please direct questions about the material provided within this release to liaobo77@ucsd.edu (A. Li)., Comment: DataPlanet Access: https://dataplanet.ucsd.edu/dataset.xhtml?persistentId=perma:83.ucsddata/UQWQAV
Published: 2023

3. Energy Calibration of Germanium Detectors for the MAJORANA DEMONSTRATOR

Author: Arnquist, I. J., Avignone III, F. T., Barabash, A. S., Barton, C. J., Bhimani, K. H., Blalock, E., Bos, B., Busch, M., Buuck, M., Caldwell, T. S., Chan, Y-D., Christofferson, C. D., Chu, P. -H., Clark, M. L., Cuesta, C., Detwiler, J. A., Efremenko, Yu., Ejiri, H., Elliott, S. R., Giovanetti, G. K., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Haufe, C. R., Henning, R., Aguilar, D. Hervas, Hoppe, E. W., Hostiuc, A., Kidd, M. F., Kim, I., Kouzes, R. T., Lannen V, T. E., Li, A., López-Castaño, J. M., Martin, E. L., Martin, R. D., Massarczyk, R., Meijer, S. J., Oli, T. K., Paudel, L. S., Pettus, W., Poon, A. W. P., Radford, D. C., Reine, A. L., Rielage, K., Ruof, N. W., Schaper, D. C., Tedeschi, D., Varner, R. L., Vasilyev, S., Wilkerson, J. F., Wiseman, C., Xu, W., Yu, C. -H., and Zhu, B. X.
Subjects: Physics - Instrumentation and Detectors, Nuclear Experiment
Abstract: The MAJORANA DEMONSTRATOR was a search for neutrinoless double-beta decay ($0\nu\beta\beta$) in the $^{76}$Ge isotope. It was staged at the 4850-foot level of the Sanford Underground Research Facility (SURF) in Lead, SD. The experiment consisted of 58 germanium detectors housed in a low background shield and was calibrated once per week by deploying a $^{228}$Th line source for 1 to 2 hours. The energy scale calibration determination for the detector array was automated using custom analysis tools. We describe the offline procedure for calibration of the Demonstrator germanium detectors, including the simultaneous fitting of multiple spectral peaks, estimation of energy scale uncertainties, and the automation of the calibration procedure.
Published: 2023
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4. Constraints on the decay of $^{180m}$Ta

Author: Arnquist, I. J., Avignone III, F. T., Barabash, A. S., Barton, C. J., Bhimani, K. H., Blalock, E., Bos, B., Busch, M., Buuck, M., Caldwell, T. S., Christofferson, C. D., Chu, P. -H., Clark, M. L., Cuesta, C., Detwiler, J. A., Efremenko, Yu., Ejiri, H., Elliott, S. R., Giovanetti, G. K., Goett, J., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Haufe, C. R., Henning, R., Aguilar, D. Hervas, Hoppe, E. W., Hostiuc, A., Kim, I., Kouzes, R. T., Lannen V, T. E., Li, A., Lopez-Castano, J. M., Massarczyk, R., Meijer, S. J., Meijer, W., Oli, T. K., Paudel, L. S., Pettus, W., Poon, A. W. P., Radford, D. C., Reine, A. L., Rielage, K., Rouyer, A., Ruof, N. W., Schaper, D. C., Schleich, S. J., Smith-Gandy, T. A., Tedeschi, D., Varner, R. L., Vasilyev, S., Watkins, S. L., Wilkerson, J. F., Wiseman, C., Xu, W., Yu, C. -H., Alves, D. S. M., and Ramani, H.
Subjects: Nuclear Experiment, High Energy Physics - Experiment
Abstract: $^{180m}$Ta is a rare nuclear isomer whose decay has never been observed. Its remarkably long lifetime surpasses the half-lives of all other known $\beta$ and electron capture decays due to the large K-spin differences and small energy differences between the isomeric and lower energy states. Detecting its decay presents a significant experimental challenge but could shed light on neutrino-induced nucleosynthesis mechanisms, the nature of dark matter and K-spin violation. For this study, we repurposed the MAJORANA DEMONSTRATOR, an experimental search for the neutrinoless double-beta decay of $^{76}$Ge using an array of high-purity germanium detectors, to search for the decay of $^{180m}$Ta. More than 17 kilograms, the largest amount of tantalum metal ever used for such a search was installed within the ultra-low background detector array. In this paper we present results from the first year of Ta data taking and provide an updated limit for the $^{180m}$Ta half-life on the different decay channels. With new limits up to 1.5 x $10^{19}$ years, we improved existing limits by one to two orders of magnitude. This result is the most sensitive search for a single $\beta$ and electron capture decay ever achieved.
Published: 2023
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5. Fundamental Symmetries, Neutrons, and Neutrinos (FSNN): Whitepaper for the 2023 NSAC Long Range Plan

Author: Acharya, B., Adams, C., Aleksandrova, A. A., Alfonso, K., An, P., Baeßler, S., Balantekin, A. B., Barbeau, P. S., Bellini, F., Bellini, V., Beminiwattha, R. S., Bernauer, J. C., Bhattacharya, T., Bishof, M., Bolotnikov, A. E., Breur, P. A., Brodeur, M., Brodsky, J. P., Broussard, L. J., Brunner, T., Burdette, D. P., Caylor, J., Chiu, M., Cirigliano, V., Clark, J. A., Clayton, S. M., Daniels, T. V., Darroch, L., Davoudi, Z., de Gouvêa, A., Dekens, W., Demarteau, M., DeMille, D., Deshpande, A., Detwiler, J. A., Dodson, G. W., Dolinski, M. J., Elliott, S. R., Engel, J., Erler, J., Filippone, B. W., Fomin, N., Formaggio, J. A., Friesen, F. Q. L., Fry, J., Fujikawa, B. K., Fuller, G., Fuyuto, K., Gallant, A. T., Gallina, G., Ruiz, A. Garcia, Ruiz, R. F. Garcia, Gardner, S., Gonzalez, F. M., Gratta, G., Gruszko, J., Gudkov, V., Guiseppe, V. E., Gutierrez, T. D., Hansen, E. V., Hardy, C. A., Haxton, W. C., Hayen, L., Hedges, S., Heeger, K. M., Heffner, M., Heise, J., Henning, R., Hergert, H., Hertzog, D. W., Aguilar, D. Hervas, Holt, J. D., Hoogerheide, S. F., Hoppe, E. W., Horoi, M., Howell, C. R., Huang, M., Hutzler, N. R., Imam, K., Ito, T. M., Jamil, A., Janssens, R. V., Jayich, A. M., Jones, B. J. P., Kammel, P., Liu, K. F., Khachatryan, V., King, P. M., Klein, J. R., Kneller, J. P., Kolomensky, Yu. G., Korsch, W., Krücken, R., Kumar, K. S., Launey, K. D., Lawrence, D., Leach, K. G., Lehnert, B., Lenardo, B. G., Li, Z., Lin, H. -W., Longfellow, B., Lopez-Caceres, S., Lunardini, C., MacLellan, R., Markoff, D. M., Maruyama, R. H., Mathews, D. G., Melconian, D., Mereghetti, E., Mohanmurthy, P., Moore, D. C., Mueller, P. E., Mumm, H. P., Nazarewicz, W., Newby, J., Nicholson, A. N., Novitski, E., Ondze, J. C. Nzobadila, O'Donnell, T., Gann, G. D. Orebi, Orrell, J. L., Ouellet, J. L., Parno, D. S., Paschke, K. D., Pastore, S., Pattie Jr, R. W., Petrov, A. A., Pitt, M. L., Plaster, B., Pocanic, D., Pocar, A., Poon, A. W. P., Radford, D. C., Rahangdale, H., Rasco, B. C., Rasiwala, H., Redwine, R. P., Ritz, A., Rogers, L., Ron, G., Saldanha, R., Sangiorgio, S., Sargsyan, G. H., Saunders, A., Savard, G., Schaper, D. C., Scholberg, K., Scielzo, N. D., Seng, C. -Y., Shindler, A., Singh, J. T., Singh, M., Singh, V., Snow, W. M., Soma, A. K., Souder, P. A., Speller, D. H., Stachurska, J., Surukuchi, P. T., Oregui, B. Tapia, Tomalak, O., Torres, J. A., Tyuka, O. A., VanDevender, B. A., Varriano, L., Vogt, R., Walker-Loud, A., Wamba, K., Watkins, S. L., Wietfeldt, F. E., Williams, W. D., Wilson, J. T., Winslow, L., Yan, X. L., Yang, L., Young, A. R., Zheng, X., and Zhou, Y.
Subjects: Nuclear Experiment, Nuclear Theory
Abstract: This whitepaper presents the research priorities decided on by attendees of the 2022 Town Meeting for Fundamental Symmetries, Neutrons and Neutrinos, which took place December 13-15, 2022 in Chapel Hill, NC, as part of the Nuclear Science Advisory Committee (NSAC) 2023 Long Range Planning process. A total of 275 scientists registered for the meeting. The whitepaper makes a number of explicit recommendations and justifies them in detail.
Published: 2023

6. Neutrinoless Double Beta Decay

Author: Adams, C., Alfonso, K., Andreoiu, C., Angelico, E., Arnquist, I. J., Asaadi, J. A. A., Avignone, F. T., Axani, S. N., Barabash, A. S., Barbeau, P. S., Baudis, L., Bellini, F., Beretta, M., Bhatta, T., Biancacci, V., Biassoni, M., Bossio, E., Breur, P. A., Brodsky, J. P., Brofferio, C., Brown, E., Brugnera, R., Brunner, T., Burlac, N., Caden, E., Calgaro, S., Cao, G. F., Cao, L., Capelli, C., Cardani, L., Fernandez, R. Castillo, Cattadori, C. M., Chana, B., Chernyak, D., Christofferson, C. D., Chu, P. -H., Church, E., Cirigliano, V., Collister, R., Comellato, T., Dalmasson, J., D'Andrea, V., Daniels, T., Darroch, L., Decowski, M. P., Demarteau, M., Peixoto, S. De Meireles, Detwiler, J. A., DeVoe, R. G., Di Domizio, S., Di Marco, N., di Vacri, M. L., Dolinski, M. J., Efremenko, Yu., Elbeltagi, M., Elliott, S. R., Engel, J., Fabris, L., Fairbank, W. M., Farine, J., Febbraro, M., Figueroa-Feliciano, E., Fields, D. E., Formaggio, J. A., Foust, B. T., Franke, B., Fu, Y., Fujikawa, B. K., Gallacher, D., Gallina, G., Garfagnini, A., Gingras, C., Gironi, L., Giuliani, A., Gold, M., Gornea, R., Grant, C., Gratta, G., Green, M. P., Grinyer, G. F., Gruszko, J., Guan, Y., Guinn, I. S., Guiseppe, V. E., Gutierrez, T. D., Hansen, E. V., Hardy, C. A., Hauptman, J., Heffner, M., Heeger, K. M., Henning, R., Hergert, H., Aguilar, D. Hervas, Hodak, R., Holt, J. D., Hoppe, E. W., Horoi, M., Huang, H. Z., Inoue, K., Jamil, A., Jochum, J., Jones, B. J. P., Kaizer, J., Karapetrov, G., Kharusi, S. Al, Kidd, M. F., Kishimoto, Y., Klein, J. R., Kolomensky, Yu. G., Kontul, I., Kornoukhov, V. N., Krause, P., Krucken, R., Kumar, K. S., Lang, K., Leach, K. G., Lenardo, B. G., Leonhardt, A., Li, A., Li, G., Li, Z., Licciardi, C., Lindsay, R., Lippi, I., Liu, J., Macko, M., MacLellan, R., Macolino, C., Majidi, S., Mamedov, F., Masbou, J., Massarczyk, R., Mastbaum, A. T., Mayer, D., Mazumdar, A., Mei, D. M., Mei, Y., Meijer, S. J., Mereghetti, E., Mertens, S., Mistry, K., Mitsui, T., Moore, D. C., Morella, M., Nattress, J. T., Neuberger, M., Ngwadla, X. E., Nones, C., Novosad, V., Nygren, D. R., Ondze, J. C. Nzobadila, O'Donnell, T., Gann, G. D. Orebi, Orrell, J. L., Ortega, G. S., Ouellet, J. L., Overman, C., Pagani, L., Palusova, V., Para, A., Pavan, M., Perna, A., Pertoldi, L., Pettus, W., Piepke, A., Piseri, P., Pocar, A., Povinec, P., Psihas, F., Pullia, A., Radford, D. C., Ramonnye, G. J, Rasiwala, H., Redchuk, M., Riboldi, S., Richardson, G., Rielage, K., Rogers, L., Rowson, P. C., Rukhadze, E., Saakyan, R., Sada, C., Salamanna, G., Salamida, F., Saldanha, R., Salvat, D. J., Sangiorgio, S., Schaper, D. C., Schoenert, S., Schwarz, M., Schwartz, S. E., Shitov, Y., Simkovic, F., Singh, V., Slavickova, M., Sousa, A. C., Spadoni, F. L., Speller, D. H., Stekl, I., Sumathi, R. R., Surukuchi, P. T., Tayloe, R., Tornow, W., Torres, J. A., Totev, T. I., Triambak, S., Tyuka, O. A., Vasilyev, S. I., Velazquez, M., Viel, S., Vogl, C., von Strum, K., Wang, Q., Waters, D., Watkins, S. L., Watts, M., Wei, W. -Z., Welliver, B., Wen, Liangjian, Wichoski, U., Wilde, S., Wilkerson, J. F., Winslow, L., Wiseman, C., Wu, X., Xu, W., Yang, H., Yang, L., Yu, C. H., Zeman, J., Zennamo, J., and Zuzel, G.
Subjects: Nuclear Experiment, Nuclear Theory
Abstract: This White Paper, prepared for the Fundamental Symmetries, Neutrons, and Neutrinos Town Meeting related to the 2023 Nuclear Physics Long Range Plan, makes the case for double beta decay as a critical component of the future nuclear physics program. The major experimental collaborations and many theorists have endorsed this white paper., Comment: white paper submitted for the Fundamental Symmetries, Neutrons, and Neutrinos Town Meeting in support of the US Nuclear Physics Long Range Planning Process
Published: 2022

7. Modeling Backgrounds for the MAJORANA DEMONSTRATOR

Author: Haufe, C. R., Arnquist, I. J., Avignone III, F. T., Barabash, A. S., Barton, C. J., Bhimani, K. H., Blalock, E., Bos, B., Busch, M., Buuck, M., Caldwell, T. S., Chan, Y-D., Christofferson, C. D., Chu, P. -H., Clark, M. L., Cuesta, C., Detwiler, J. A., Efremenko, Yu., Ejiri, H., Elliott, S. R., Giovanetti, G. K., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Henning, R., Aguilar, D. Hervas, Hoppe, E. W., Hostiuc, A., Kidd, M. F., Kim, I., Kouzes, R. T., Lannen V, T. E., Li, A., Lopez, A. M., López-Castaño, J. M., Martin, E. L., Martin, R. D., Massarczyk, R., Meijer, S. J., Oli, T. K., Othman, G., Paudel, L. S., Pettus, W., Poon, A. W. P., Radford, D. C., Reine, A. L., Rielage, K., Ruof, N. W., Schaper, D. C., Tedeschi, D., Varner, R. L., Vasilyev, S., Wilkerson, J. F., Wiseman, C., Xu, W., Yu, C. -H., and Zhu, B. X.
Subjects: Nuclear Experiment
Abstract: The MAJORANA DEMONSTRATOR is a neutrinoless double-beta decay ($0\nu\beta\beta$) experiment containing $\sim$30 kg of p-type point contact germanium detectors enriched to 88% in 76Ge and $\sim$14 kg of natural germanium detectors. The detectors are housed in two electroformed copper cryostats and surrounded by a graded passive shield with active muon veto. An extensive radioassay campaign was performed prior to installation to insure the use of ultra-clean materials. The DEMONSTRATOR achieved one of the lowest background rates in the region of the $0\nu\beta\beta$ Q-value, 15.7 $\pm$ 1.4 cts/(FWHM t y) from the low-background configuration spanning most of the 64.5 kg-yr active exposure. Nevertheless this background rate is a factor of five higher than the projected background rate. This discrepancy arises from an excess of events from the 232Th decay chain. Background model fits aim to understand this deviation from assay-based projections, potentially determine the source(s) of observed backgrounds, and allow a precision measurement of the two-neutrino double-beta decay half-life. The fits agree with earlier simulation studies, which indicate the origin of the 232Th excess is not from a near-detector component and have informed design decisions for the next-generation LEGEND experiment. Recent findings have narrowed the suspected locations for the excess activity, motivating a final simulation and assay campaign to complete the background model., Comment: 8 pages, 6 figures, Proceedings from the Low Radioactivity Techniques Workshop 2022 in Rapid City, SD, USA
Published: 2022

8. Charge Trapping and Energy Performance of the MAJORANA DEMONSTRATOR

Author: Arnquist, I. J., Avignone III, F. T., Barabash, A. S., Barton, C. J., Bhimani, K. H., Blalock, E., Bos, B., Busch, M., Buuck, M., Caldwell, T. S., Chan, Y-D., Christofferson, C. D., Chu, P. -H., Clark, M. L., Cuesta, C., Detwiler, J. A., Efremenko, Yu., Ejiri, H., Elliott, S. R., Giovanetti, G. K., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Haufe, C. R., Henning, R., Aguilar, D. Hervas, Hoppe, E. W., Hostiuc, A., Kidd, M. F., Kim, I., Kouzes, R. T., Lannen V, T. E., Li, A., López-Castaño, J. M., Martin, E. L., Martin, R. D., Massarczyk, R., Meijer, S. J., Mertens, S., Oli, T. K., Othman, G., Paudel, L. S., Pettus, W., Poon, A. W. P., Radford, D. C., Reine, A. L., Rielage, K., Ruof, N. W., Schaper, D. C., Tedeschi, D., Varner, R. L., Vasilyev, S., Wilkerson, J. F., Wiseman, C., Xu, W., Yu, C. -H., and Zhu, B. X.
Subjects: Physics - Instrumentation and Detectors
Abstract: P-type point contact (PPC) high-purity germanium detectors are an important technology in astroparticle and nuclear physics due to their superb energy resolution, low noise, and pulse shape discrimination capabilities. Analysis of data from the MAJORANA DEMONSTRATOR, a neutrinoless double-beta decay experiment deploying PPC detectors enriched in $^{76}$Ge, has led to several novel improvements in the analysis of PPC signals. In this work we discuss charge trapping in PPC detectors and its effect on energy resolution. Small dislocations or impurities in the crystal lattice result in trapping of charge carriers from an ionization event of interest, attenuating the signal and degrading the measured energy. We present a modified digital pole-zero correction to the signal energy estimation that counters the effects of charge trapping and improves the energy resolution of the MAJORANA DEMONSTRATOR by approximately 30% to around 2.4 keV FWHM at 2039 keV, the $^{76}$Ge $Q$-value. An alternative approach achieving similar resolution enhancement is also presented., Comment: 12 pages, 13 figures
Published: 2022
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9. Interpretable Boosted Decision Tree Analysis for the Majorana Demonstrator

Author: Arnquist, I. J., Avignone III, F. T., Barabash, A. S., Barton, C. J., Bhimani, K. H., Blalock, E., Bos, B., Busch, M., Buuck, M., Caldwell, T. S., Chan, Y -D., Christofferson, C. D., Chu, P. -H., Clark, M. L., Cuesta, C., Detwiler, J. A., Efremenko, Yu., Elliott, S. R., Giovanetti, G. K., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Haufe, C. R., Henning, R., Aguilar, D. Hervas, Hoppe, E. W., Hostiuc, A., Kidd, M. F., Kim, I., Kouzes, R. T., Lannen V, T. E., Li, A., Lopez-Castano, J. M., Martin, E. L., Martin, R. D., Massarczyk, R., Meijer, S. J., Oli, T. K., Othman, G., Paudel, L. S., Pettus, W., Poon, A. W. P., Radford, D. C., Reine, A. L., Rielage, K., Ruof, N. W., Schaper, D. C., Tedeschi, D., Varner, R. L., Vasilyev, S., Wilkerson, J. F., Wiseman, C., Xu, W., and Yu, C. -H.
Subjects: Physics - Data Analysis, Statistics and Probability, Computer Science - Machine Learning, Nuclear Experiment
Abstract: The Majorana Demonstrator is a leading experiment searching for neutrinoless double-beta decay with high purity germanium detectors (HPGe). Machine learning provides a new way to maximize the amount of information provided by these detectors, but the data-driven nature makes it less interpretable compared to traditional analysis. An interpretability study reveals the machine's decision-making logic, allowing us to learn from the machine to feedback to the traditional analysis. In this work, we have presented the first machine learning analysis of the data from the Majorana Demonstrator; this is also the first interpretable machine learning analysis of any germanium detector experiment. Two gradient boosted decision tree models are trained to learn from the data, and a game-theory-based model interpretability study is conducted to understand the origin of the classification power. By learning from data, this analysis recognizes the correlations among reconstruction parameters to further enhance the background rejection performance. By learning from the machine, this analysis reveals the importance of new background categories to reciprocally benefit the standard Majorana analysis. This model is highly compatible with next-generation germanium detector experiments like LEGEND since it can be simultaneously trained on a large number of detectors., Comment: 13 pages, 9 figures
Published: 2022
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10. Final Result of the MAJORANA DEMONSTRATOR's Search for Neutrinoless Double-$\beta$ Decay in $^{76}$Ge

Author: Arnquist, I. J., Avignone III, F. T., Barabash, A. S., Barton, C. J., Barton, P. J., Bhimani, K. H., Blalock, E., Bos, B., Busch, M., Buuck, M., Caldwell, T. S., Chan, Y-D., Christofferson, C. D., Chu, P. -H., Clark, M. L., Cuesta, C., Detwiler, J. A., Efremenko, Yu., Ejiri, H., Elliott, S. R., Giovanetti, G. K., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Haufe, C. R., Henning, R., Aguilar, D. Hervas, Hoppe, E. W., Hostiuc, A., Kidd, M. F., Kim, I., Kouzes, R. T., Lannen V, T. E., Li, A., Lopez, A. M., López-Castaño, J. M., Martin, E. L., Martin, R. D., Massarczyk, R., Meijer, S. J., Mertens, S., Oli, T. K., Othman, G., Paudel, L. S., Pettus, W., Poon, A. W. P., Radford, D. C., Reine, A. L., Rielage, K., Ruof, N. W., Schaper, D. C., Tedeschi, D., Varner, R. L., Vasilyev, S., Wilkerson, J. F., Wiseman, C., Xu, W., Yu, C. -H., and Zhu, B. X.
Subjects: Nuclear Experiment, High Energy Physics - Experiment, Physics - Instrumentation and Detectors
Abstract: The MAJORANA DEMONSTRATOR searched for neutrinoless double-$\beta$ decay ($0\nu\beta\beta$) of $^{76}$Ge using modular arrays of high-purity Ge detectors operated in vacuum cryostats in a low-background shield. The arrays operated with up to 40.4 kg of detectors (27.2 kg enriched to $\sim$88\% in $^{76}$Ge). From these measurements, the DEMONSTRATOR has accumulated 64.5 kg yr of enriched active exposure. With a world-leading energy resolution of 2.52 keV FWHM at the 2039 keV $Q_{\beta\beta}$ (0.12\%), we set a half-life limit of $0\nu\beta\beta$ in $^{76}$Ge at $T_{1/2}>8.3\times10^{25}$ yr (90\% C.L.). This provides a range of upper limits on $m_{\beta\beta}$ of $(113-269)$ meV (90\% C.L.), depending on the choice of nuclear matrix elements., Comment: 8 pages, 2 figures
Published: 2022
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11. Exotic dark matter search with the Majorana Demonstrator

Author: Arnquist, I. J., Avignone III, F. T., Barabash, A. S., Barton, C. J., Bhimani, K. H., Blalock, E., Bos, B., Busch, M., Buuck, M., Caldwell, T. S., Chan, Y-D., Christofferson, C. D., Chu, P. -H., Clark, M. L., Cuesta, C., Detwiler, J. A., Efremenko, Yu., Ejiri, H., Elliott, S. R., Giovanetti, G. K., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Haufe, C. R., Henning, R., Aguilar, D. Hervas, Hoppe, E. W., Hostiuc, A., Kidd, M. F., Kim, I., Kouzes, R. T., Lannen V, T. E., Li, A., Lopez, A. M., López-Castaño, J. M., Martin, E. L., Martin, R. D., Massarczyk, R., Meijer, S. J., Mertens, S., Oli, T. K., Othman, G., Paudel, L. S., Pettus, W., Poon, A. W. P., Radford, D. C., Reine, A. L., Rielage, K., Ruof, N. W., Schaper, D. C., Tedeschi, D., Varner, R. L., Vasilyev, S., Wilkerson, J. F., Wiseman, C., Xu, W., Yu, C. -H., and Zhu, B. X.
Subjects: High Energy Physics - Experiment, High Energy Physics - Phenomenology
Abstract: With excellent energy resolution and ultra-low 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, $\nu_s \rightarrow \nu_a$. We report new limits on fermionic dark matter absorption ($\chi + A \rightarrow \nu + A$) and sub-GeV DM-nucleus 3$\rightarrow$2 scattering ($\chi + \chi + A \rightarrow \phi + 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., Comment: 7 pages, 6 figures
Published: 2022
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12. Search for solar axions via axion-photon coupling with the Majorana Demonstrator

Author: Arnquist, I. J., Avignone III, F. T., Barabash, A. S., Barton, C. J., Bhimani, K. H., Blalock, E., Bos, B., Busch, M., Buuck, M., Caldwell, T. S., Chan, Y-D., Christofferson, C. D., Chu, P. -H., Clark, M. L., Cuesta, C., Detwiler, J. A., Efremenko, Yu., Ejiri, H., Elliott, S. R., Giovanetti, G. K., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Haufe, C. R., Henning, R., Aguilar, D. Hervas, Hoppe, E. W., Hostiuc, A., Kidd, M. F., Kim, I., Kouzes, R. T., Lannen V, T. E., Li, A., Lopez, A. M., López-Castaño, J. M., Martin, E. L., Martin, R. D., Massarczyk, R., Meijer, S. J., Oli, T. K., Othman, G., Paudel, L. S., Pettus, W., Poon, A. W. P., Radford, D. C., Reine, A. L., Rielage, K., Ruof, N. W., Schaper, D. C., Tedeschi, D., Varner, R. L., Vasilyev, S., Wilkerson, J. F., Wiseman, C., Xu, W., Yu, C. -H., and Zhu, B. X.
Subjects: Nuclear Experiment, High Energy Physics - Experiment
Abstract: Axions were originally proposed to explain the strong-CP problem in QCD. Through the axion-photon coupling, the Sun could be a major source of axions, which could be measured in solid state detection experiments with enhancements due to coherent Primakoff-Bragg scattering. The Majorana Demonstrator experiment has searched for solar axions with a set of $^{76}$Ge-enriched high purity germanium detectors using a 33 kg-yr exposure collected between Jan. 2017 and Nov. 2019. A temporal-energy analysis gives a new limit on the axion-photon coupling as $g_{a\gamma}<1.45\times 10^{-9}$ GeV$^{-1}$ (95% C.I.) for axions with mass up to 100 eV/$c^2$. This improves laboratory-based limits between about 1 eV/$c^2$ and 100 eV/$c^2$., Comment: Minor updates to match published version
Published: 2022
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13. Experimental study of 13C({\alpha},n)16O reactions in the Majorana Demonstrator calibration data

Author: MAJORANA Collaboration, Arnquist, I. J., Avignone III, F. T., Barabash, A. S., Barton, C. J., Bhimani, K. H., Blalock, E., Bos, B., Busch, M., Buuck, M., Caldwell, T. S., Chan, Y-D., Christofferson, C. D., Chu, P. -H., Clark, M. L., Cuesta, C., Detwiler, J. A., Efremenko, Yu., Ejiri, H., Elliott, S. R., Giovanetti, G. K., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Haufe, C. R., Henning, R., Aguilar, D. Hervas, Hoppe, E. W., Hostiuc, A., Kidd, M. F., Kim, I., Kouzes, R. T., Lannen V, T. E., Li, A., Lopez, A. M., Lopez-Castano, J. M., Martin, E. L., Martin, R. D., Massarczyk, R., Meijer, S. J., Oli, T. K., Othman, G., Paudel, L. S., Pettus, W., Poon, A. W. P., Radford, D. C., Reine, A. L., Rielage, K., Ruof, N. W., Tedeschi, D., Varner, R. L., Vasilyev, S., Wilkerson, J. F., Wiseman, C., Xu, W., Yu, C. -H., and Zhu, B. X.
Subjects: Nuclear Experiment, High Energy Physics - Experiment, Physics - Instrumentation and Detectors
Abstract: Neutron captures and delayed decays of reaction products are common sources of backgrounds in ultra-rare event searches. In this work, we studied $^{13}$C($\alpha,n)^{16}$O reactions induced by $\alpha$-particles emitted within the calibration sources of the \textsc{Majorana Demonstrator}. These sources are thorium-based calibration standards enclosed in carbon-rich materials. The reaction rate was estimated by using the 6129-keV $\gamma$-rays emitted from the excited $^{16}$O states that are populated when the incoming $\alpha$-particles exceed the reaction Q-value. Thanks to the excellent energy performance of the \textsc{Demonstrator}'s germanium detectors, these characteristic photons can be clearly observed in the calibration data. Facilitated by \textsc{Geant4} simulations, a comparison between the observed 6129-keV photon rates and predictions by a TALYS-based software was performed. The measurements and predictions were found to be consistent, albeit with large statistical uncertainties. This agreement provides support for background projections from ($\alpha,n$)-reactions in future double-beta decay search efforts., Comment: Published version
Published: 2022
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14. Search for charge nonconservation and Pauli exclusion principle violation with the Majorana Demonstrator

Author: MAJORANA Collaboration, Arnquist, I. J., Avignone III, F. T., Barabash, A. S., Barton, C. J., Bhimani, K. H., Blalock, E., Bos, B., Busch, M., Buuck, M., Caldwell, T. S., Chan, Y-D., Christofferson, C. D., Chu, P. -H., Clark, M. L., Cuesta, C., Detwiler, J. A., Efremenko, Yu., Ejiri, H., Elliott, S. R., Giovanetti, G. K., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Haufe, C. R., Henning, R., Aguilar, D. Hervas, Hoppe, E. W., Hostiuc, A., Kidd, M. F., Kim, I., Kouzes, R. T., Lannen V, T. E., Li, A., Lopez, A. M., López-Castaño, J. M., Martin, E. L., Martin, R. D., Massarczyk, R., Meijer, S. J., Oli, T. K., Paudel, L. S., Pettus, W., Poon, A. W. P., Radford, D. C., Reine, A. L., Rielage, K., Ruof, N. W., Schaper, D. C., Tedeschi, D., Varner, R. L., Vasilyev, S., Wilkerson, J. F., Wiseman, C., Xu, W., Yu, C. -H., and Zhu, B. X.
Subjects: Nuclear Experiment, High Energy Physics - Experiment
Abstract: Charge conservation and the Pauli exclusion principle (PEP) result from fundamental symmetries in the Standard Model, and are typically taken as axiomatic. High-precision tests for small violations of these symmetries could point to new physics. In this work we consider three models for violation of these processes which would produce detectable ionization in the high-purity germanium detectors of the Majorana Demonstrator. Using a 37.5 kg-yr exposure, we report a new lower limit on the electron mean lifetime of $\tau_e > 3.2 \times 10^{25}$ yr (90\% CL), the best result for this decay channel ($e \rightarrow \nu_e \overline{\nu_e} \nu_e$ or more generally $e \rightarrow \mathrm{invisibles}$) in more than two decades. We also present searches for two types of violation of the PEP, setting new limits on the probability of two electrons forming a symmetric quantum state. Using our $^{228}$Th calibration data set, which introduces electrons new to the system through electron-positron pair production, we obtain a world-leading model-independent limit for a terrestrial experiment of $\beta^2/2 < 1.0 \times 10^{-3}$ (99.7\% CL). Our 37.5 kg-yr exposure is also used to search for a process where an electron in an atomic system spontaneously violates the PEP, resulting in a model-dependent upper limit of $\beta^2/2 < 1.0 \times 10^{-48}$ (90\% CL).
Published: 2022
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15. Search for Spontaneous Radiation from Wavefunction Collapse in the Majorana Demonstrator

Author: Arnquist, I. J., Avignone III, F. T., Barabash, A. S., Barton, C. J., Blalock, E., Bos, B., Busch, M., Buuck, M., Caldwell, T. S., Chan, Y-D., Christofferson, C. D., Chu, P. -H., Clark, M. L., Cuesta, C., Detwiler, J. A., Efremenko, Yu., Ejiri, H., Elliott, S. R., Giovanetti, G. K., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Haufe, C. R., Henning, R., Aguilar, D. Hervas, Hoppe, E. W., Hostiuc, A., Kim, I., Kouzes, R. T., Lannen V, T. E., Lopez, A. M., López-Castaño, J. M., Martin, E. L., Martin, R. D., Massarczyk, R., Meijer, S. J., Oli, T. K., Othman, G., Paudel, L. S., Pettus, W., Poon, A. W. P., Radford, D. C., Reine, A. L., Rielage, K., Ruof, N. W., Tedeschi, D., Varner, R. L., Vasilyev, S., Wilkerson, J. F., Wiseman, C., Xu, W., Yu, C. -H., and Zhu, B. X.
Subjects: Nuclear Experiment, High Energy Physics - Experiment
Abstract: The Majorana Demonstrator neutrinoless double-beta decay experiment comprises a 44 kg (30 kg enriched in $^{76}\mathrm{Ge}$) array of $p$-type, point-contact germanium detectors. With its unprecedented energy resolution and ultralow backgrounds, Majorana also searches for rare event signatures from beyond standard model physics in the low energy region below 100 keV. In this Letter, we test the continuous spontaneous localization (CSL) model, one of the mathematically well-motivated wave function collapse models aimed at solving the long-standing unresolved quantum mechanical measurement problem. While the CSL predicts the existence of a detectable radiation signature in the x-ray domain, we find no evidence of such radiation in the 19--100 keV range in a 37.5 kg-y enriched germanium exposure collected between December 31, 2015, and November 27, 2019, with the Demonstrator. We explored both the non-mass-proportional (n-m-p) and the mass-proportional (m-p) versions of the CSL with two different assumptions: that only the quasifree electrons can emit the x-ray radiation and that the nucleus can coherently emit an amplified radiation. In all cases, we set the most stringent upper limit to date for the white CSL model on the collapse rate, $\lambda$, providing a factor of 40--100 improvement in sensitivity over comparable searches. Our limit is the most stringent for large parts of the allowed parameter space. If the result is interpreted in terms of the Di\`osi-Penrose gravitational wave function collapse model, the lower bound with a 95% confidence level is almost an order of magnitude improvement over the previous best limit., Comment: This document was corrected in accordance with the erratum: https://doi.org/10.1103/PhysRevLett.130.239902. The number presented in the recent version of this article is correct
Published: 2022
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16. 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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17. Signatures of muonic activation in the Majorana Demonstrator

Author: 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., Edwards, T. R., Efremenko, Yu., Ejiri, H., Elliott, S. R., Giovanetti, G. K., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Haufe, C. R., Henning, R., Aguilar, D. Hervas, Hoppe, E. W., Hostiuc, A., Kidd, M. F., Kim, I., Kouzes, R. T., Lannen V, T. E., Lopez, A. M., López-Castaño, J. M., Martin, E. L., Martin, R. D., Massarczyk, R., Meijer, S. J., Mertens, S., Oli, T. K., Othman, G., Paudel, L. S., Pettus, W., Poon, A. W. P., Radford, D. C., Reine, A. L., Rielage, K., Ruof, N. W., Tedeschi, D., Varner, R. L., Vasilyev, S., Wilkerson, J. F., Wiseman, C., Xu, W., Yu, C. -H., and Zhu, B. X.
Subjects: Nuclear Experiment, Physics - Instrumentation and Detectors
Abstract: Experiments searching for very rare processes such as neutrinoless double-beta decay require a detailed understanding of all sources of background. Signals from radioactive impurities present in construction and detector materials can be suppressed using a number of well-understood techniques. Background from in-situ cosmogenic interactions can be reduced by siting an experiment deep underground. However, the next generation of such experiments have unprecedented sensitivity goals of 10$^{28}$ years half-life with background rates of 10$^{-5}$cts/(keV kg yr) in the region of interest. To achieve these goals, the remaining cosmogenic background must be well understood. In the work presented here, Majorana Demonstrator data is used to search for decay signatures of meta-stable germanium isotopes. Contributions to the region of interest in energy and time are estimated using simulations, and compared to Demonstrator data. Correlated time-delayed signals are used to identify decay signatures of isotopes produced in the germanium detectors. A good agreement between expected and measured rate is found and different simulation frameworks are used to estimate the uncertainties of the predictions. The simulation campaign is then extended to characterize the background for the LEGEND experiment, a proposed tonne-scale effort searching for neutrinoless double-beta decay in $^{76}$Ge., Comment: 14 pages, 12 figures
Published: 2021
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18. LEGEND-1000 Preconceptual Design Report

Author: LEGEND Collaboration, Abgrall, N., Abt, I., Agostini, M., Alexander, A., Andreoiu, C., Araujo, G. R., Avignone III, F. T., Bae, W., Bakalyarov, A., Balata, M., Bantel, M., Barabanov, I., Barabash, A. S., Barbeau, P. S., Barton, C. J., Barton, P. J., Baudis, L., Bauer, C., Bernieri, E., Bezrukov, L., Bhimani, K. H., Biancacci, V., Blalock, E., Bolozdynya, A., Borden, S., Bos, B., Bossio, E., Boston, A., Bothe, V., Bouabid, R., Boyd, S., Brugnera, R., Burlac, N., Busch, M., Caldwell, A., Caldwell, T. S., Carney, R., Cattadori, C., Chan, Y. -D., Chernogorov, A., Christofferson, C. D., Chu, P. -H., Clark, M., Cohen, T., Combs, D., Comellato, T., Cooper, R. J., Costa, I. A., D'Andrea, V., Detwiler, J. A., Di Giacinto, A., Di Marco, N., Dobson, J., Drobizhev, A., Durand, M. R., Edzards, F., Efremenko, Yu., Elliott, S. R., Engelhardt, A., Fajt, L., Faud, N., Febbraro, M. T., Ferella, F., Fields, D. E., Fischer, F., Fomina, M., Fox, H., Franchi, J., Gala, R., Galindo-Uribarri, A., Gangapshev, A., Garfagnini, A., Geraci, A., Gilbert, C., Gold, M., Gooch, C., Gradwohl, K. P., Green, M. P., Grinyer, G. F., Grobov, A., Gruszko, J., Guinn, I., Guiseppe, V. E., Gurentsov, V., Gurov, Y., Gusev, K., Hacket, B., Hagemann, F., Hakenmüeller, J., Haranczyk, M., Hauertmann, L., Haufe, C. R., Hayward, C., Heffron, B., Henkes, F., Henning, R., Aguilar, D. Hervas, Hinton, J., Hodak, R., Hoffmann, H., Hofmann, W., Hostiuc, A., Huang, J., Hult, M., Mirza, M. Ibrahim, Jochum, J., Jones, R., Judson, D., Junker, M., Kaizer, J., Kazalov, V., Kermaïdic, Y., Khushbakht, H., Kidd, M., Kihm, T., Kilgus, K., Kim, I., Klimenko, A., Knöpfle, K. T., Kochetov, O., Konovalov, S. I., Kontul, I., Kool, K., Kormos, L. L., Kornoukhov, V. N., Korosec, M., Krause, P., Kuzminov, V. V., López-Castaño, J. M., Lang, K., Laubenstein, M., León, E., Lehnert, B., Leonhardt, A., Li, A., Lindner, M., Lippi, I., Liu, X., Liu, J., Loomba, D., Lubashevskiy, A., Lubsandorzhiev, B., Lusardi, N., Müller, Y., Macko, M., Macolino, C., Majorovits, B., Mamedov, F., Maneschg, W., Manzanillas, L., Marshall, G., Martin, R. D., Martin, E. L., Massarczyk, R., Mei, D., Meijer, S. J., Mertens, S., Misiaszek, M., Mondragon, E., Morella, M., Morgan, B., Mroz, T., Muenstermann, D., Nave, C. J., Nemchenok, I., Neuberger, M., Oli, T. K., Gann, G. Orebi, Othman, G., Palušova, V., Panth, R., Papp, L., Paudel, L. S., Pelczar, K., Perez, J. Perez, Pertoldi, L., Pettus, W., Piseri, P., Poon, A. W. P., Povinec, P., Pullia, A., Radford, D. C., Ramachers, Y. A., Ransom, C., Rauscher, L., Redchuk, M., Reine, A. L., Riboldi, S., Rielage, K., Rozov, S., Rukhadze, E., Rumyantseva, N., Runge, J., Ruof, N. W., Saakyan, R., Sailer, S., Salamanna, G., Salamida, F., Salvat, D. J., Sandukovsky, V., Schönert, S., Schültz, A., Schütt, M., Schaper, D. C., Schreiner, J., Schulz, O., Schuster, M., Schwarz, M., Schwingenheuer, B., Selivanenko, O., Shafiee, M., Shevchik, E., Shirchenko, M., Shitov, Y., Simgen, H., Simkovic, F., Skorokhvatov, M., Slavickova, M., Smolek, K., Smolnikov, A., Solomon, J. A., Song, G., Starosta, K., Stekl, I., Stommel, M., Stukov, D., Sumathi, R. R., Sweigart, D. A., Szczepaniec, K., Taffarello, L., Tagnani, D., Tayloe, R., Tedeschi, D., Turqueti, M., Varner, R. L., Vasilyev, S., Veresnikova, A., Vetter, K., Vignoli, C., Vogl, C., von Sturm, K., Waters, D., Waters, J. C., Wei, W., Wiesinger, C., Wilkerson, J. F., Willers, M., Wiseman, C., Wojcik, M., Wu, V. H. -S., Xu, W., Yakushev, E., Ye, T., Yu, C. -H., Yumatov, V., Zaretski, N., Zeman, J., Zhitnikov, I., Zinatulina, D., Zschocke, A. -K., Zsigmond, A. J., Zuber, K., and Zuzel, G.
Subjects: Physics - Instrumentation and Detectors, Nuclear Experiment
Abstract: We propose the construction of LEGEND-1000, the ton-scale Large Enriched Germanium Experiment for Neutrinoless $\beta \beta$ Decay. This international experiment is designed to answer one of the highest priority questions in fundamental physics. It consists of 1000 kg of Ge detectors enriched to more than 90% in the $^{76}$Ge isotope operated in a liquid argon active shield at a deep underground laboratory. By combining the lowest background levels with the best energy resolution in the field, LEGEND-1000 will perform a quasi-background-free search and can make an unambiguous discovery of neutrinoless double-beta decay with just a handful of counts at the decay $Q$ value. The experiment is designed to probe this decay with a 99.7%-CL discovery sensitivity in the $^{76}$Ge half-life of $1.3\times10^{28}$ years, corresponding to an effective Majorana mass upper limit in the range of 9-21 meV, to cover the inverted-ordering neutrino mass scale with 10 yr of live time.
Published: 2021

19. The Majorana Demonstrator's Search for Double-Beta Decay of $^{76}$Ge to Excited States of $^{76}$Se

Author: 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., 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., Aguilar, D. Hervas, Hoppe, E. W., Hostiuc, A., Kidd, M. F., 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., Paudel, L. S., Pettus, W., Poon, A. W. P., Radford, D. C., Reine, A. L., Rielage, K., Ruof, N. W., Saykı, B., Stortini, M. J., Tedeschi, D., Varner, R. L., Vasilyev, S., Wilkerson, J. F., Wiseman, C., Xu, W., Yu, C. -H., and Zhu, B. X.
Subjects: Nuclear Experiment
Abstract: The Majorana Demonstrator is a neutrinoless double-beta decay search consisting of a low-background modular array of high-purity germanium detectors, $\sim2/3$ of which are enriched to 88\% in $^{76}$Ge. The experiment is also searching for double-beta decay of $^{76}$Ge to excited states (e.s.) in $^{76}$Se. $^{76}$Ge can decay into three daughter states of $^{76}$Se, with clear event signatures consisting of a $\beta\beta$-decay followed by the prompt emission of one or two $\gamma$-rays. This results with high probability in multi-detector coincidences. The granularity of the Demonstrator detector array enables powerful discrimination of this event signature from backgrounds. Using 41.9~kg-y of isotopic exposure, the Demonstrator has set world leading limits for each e.s.\ decay of $^{76}$Ge, with 90\% CL lower half-life limits in the range of $(0.75-4.0)\times10^{24}$~y. In particular, for the $2\nu$ transition to the first $0^+$ e.s.\ of $^{76}$Se, a lower half-life limit of $7.5\times10^{23}$~y at 90\% CL was achieved., Comment: 16 pages, 11 figures
Published: 2020
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20. $\alpha$-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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21. 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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22. 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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23. 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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24. 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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25. 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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26. 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

27. 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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28. 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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29. The Majorana Demonstrator Status and Preliminary Results

Author: Yu, C. -H., 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., 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., Ruff, 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: Nuclear Experiment, Physics - Instrumentation and Detectors
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 Q$_{\beta\beta}$. 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., Comment: 5 pages, 2 figures. Proceeding for the "16th International Symposium on Capture Gamma-Ray Spectroscopy and Related Topics (CGS16)", 18-22 September 2017
Published: 2018
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30. 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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31. A Review and Outlook for the Removal of Radon-Generated Po-210 Surface Contamination

Author: Guiseppe, V. E., Christofferson, C. D., Hair, K. R., and Adams, F. M.
Subjects: Physics - Instrumentation and Detectors, Nuclear Experiment
Abstract: The next generation low-background detectors operating deep underground aim for unprecedented low levels of radioactive backgrounds. The deposition and presence of radon progeny on detector surfaces is an added source of energetic background events. In addition to limiting the detector material's radon exposure in order to reduce potential surface backgrounds, it is just as important to clean surfaces to remove inevitable contamination. Such studies of radon progeny removal have generally found that a form of etching is effective at removing some of the progeny (Bi and Pb), however more aggressive techniques, including electropolishing, have been shown to effectively remove the Po atoms. In the absence of an aggressive etch, a significant fraction of the Po atoms are believed to either remain behind within the surface or redeposit from the etching solution back onto the surface. We explore the chemical nature of the aqueous Po ions and the effect of the oxidation state of Po to maximize the Po ions remaining in the etching solution of contaminated Cu surfaces. We present a review of the previous studies of surface radon progeny removal and our findings on the role of oxidizing agents and a cell potential in the preparation of a clean etching technique., Comment: Proceedings of the Low Radioactivity Techniques (LRT) 2017, Seoul, South Korea, May 24-26, 2017
Published: 2017
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32. 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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33. 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

34. 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

35. 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

36. 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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37. 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

38. 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

39. 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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40. 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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41. 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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42. 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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43. 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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44. 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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45. Search for Pauli Exclusion Principle Violating Atomic Transitions and Electron Decay with a P-type Point Contact Germanium Detector

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, A. S., Chan, Y-D., Christofferson, C. D., Chu, P. -H., Cuesta, C., Detwiler, J. A., Dunagan, C., Efremenko, Yu., Ejiri, H., Elliott, S. R., Finnerty, P. S, Galindo-Uribarri, A., Gilliss, T., Giovanetti, G. K., Goett, J., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., 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., LaFerriere, B. D., Leon, J., MacMullin, J., Martin, R. D., Massarczyk, R., Meijer, S. J., Mertens, S., Orrell, J. L., O'Shaughnessy, C., Poon, A. W. P., Radford, D. C., Rager, J., Rielage, K., Robertson, R. G. H., Romero-Romero, E., 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., and Zhitnikov, I.
Subjects: Nuclear Experiment, Physics - Instrumentation and Detectors
Abstract: A search for Pauli-exclusion-principle-violating K-alpha electron transitions was performed using 89.5 kg-d of data collected with a p-type point contact high-purity germanium detector operated at the Kimballton Underground Research Facility. A lower limit on the transition lifetime of 5.8x10^30 seconds at 90% C.L. was set by looking for a peak at 10.6 keV resulting from the x-ray and Auger electrons present following the transition. A similar analysis was done to look for the decay of atomic K-shell electrons into neutrinos, resulting in a lower limit of 6.8x10^30 seconds at 90 C.L. It is estimated that the MAJORANA DEMONSTRATOR, a 44 kg array of p-type point contact detectors that will search for the neutrinoless double-beta decay of 76-Ge, could improve upon these exclusion limits by an order of magnitude after three years of operation.
Published: 2016
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46. Delayed charge recovery discrimination of passivated surface alpha events in P-type point-contact detectors

Author: Gruszko, J., 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., Fullmer, A., Galindo-Uribarri, A., Gilliss, T., Giovanetti, G. K., Green, M. P., Guinn, I. S., Guiseppe, V. E., Henning, R., Hoppe, E. W., Howe, M. A., Jasinski, B. R., Keeter, K. J., Kidd, M. F., Konovalov, S. I., Kouzes, R. T., Leon, J., Lopez, A. M., MacMullin, J., Martin, R. D., Massarczyk, R., Meijer, S. J., Mertens, S., Orrell, J. L., O'Shaughnessy, C., Poon, A. W. P., Radford, D. C., Rager, J., Rielage, K., Robertson, R. G. H., Romero-Romero, E., 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., and Zhitnikov, I.
Subjects: Physics - Instrumentation and Detectors, Nuclear Experiment
Abstract: The Majorana Demonstrator searches for neutrinoless double-beta decay of $^{76}$Ge using arrays of high-purity germanium detectors. If observed, this process would demonstrate that lepton number is not a conserved quantity in nature, with implications for grand-unification and for explaining the predominance of matter over antimatter in the universe. A problematic background in such large granular detector arrays is posed by alpha particles. In the Majorana Demonstrator, events have been observed that are consistent with energy- degraded alphas originating on the passivated surface, leading to a potential background contribution in the region-of-interest for neutrinoless double-beta decay. However, it is also observed that when energy deposition occurs very close to the passivated surface, charges drift through the bulk onto that surface, and then drift along it with greatly reduced mobility. This leads to both a reduced prompt signal and a measurable change in slope of the tail of a recorded pulse. In this contribution we discuss the characteristics of these events and the development of a filter that can identify the occurrence of this delayed charge recovery, allowing for the efficient rejection of passivated surface alpha events in analysis., Comment: 3 pages, 3 figures, Proceedings of the XXVII International Conference on Neutrino Physics and Astrophysics
Published: 2016
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47. Initial Results from the MAJORANA DEMONSTRATOR

Author: Elliott, S. R., 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., Fullmer, A., Galindo-Uribarri, A., Gilliss, T., Giovanetti, G. K., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Henning, R., Hoppe, E. W., Howe, M. A., Jasinski, B. R., Keeter, K. J., Kidd, M. F., Konovalov, S. I., Kouzes, R. T., Leon, J., Lopez, A. M., MacMullin, J., Martin, R. D., Massarczyk, R., Meijer, S. J., Mertens, S., Orrell, J. L., O'Shaughnessy, C., Poon, A. W. P., Radford, D. C., Rager, J., Rielage, K., Robertson, R. G. H., Romero-Romero, E., 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., and Zhitnikov, I.
Subjects: Nuclear Experiment, High Energy Physics - Experiment, Physics - Instrumentation and Detectors
Abstract: Neutrinoless double-beta decay searches seek to determine the nature of neutrinos, the existence of a lepton violating process, and the effective Majorana neutrino mass. The {\sc Majorana} Collaboration is assembling an array of high purity Ge detectors to search for neutrinoless double-beta decay in $^{76}$Ge. The {\sc Majorana Demonstrator} is composed of 44.8~kg (29.7 kg enriched in $^{76}$Ge) of Ge detectors in total, split between two modules contained in a low background shield at the Sanford Underground Research Facility in Lead, South Dakota. The initial goals of the {\sc Demonstrator} are to establish the required background and scalability of a Ge-based, next-generation, tonne-scale experiment. Following a commissioning run that began in 2015, the first detector module started physics data production in early 2016. We will discuss initial results of the Module 1 commissioning and first physics run, as well as the status and potential physics reach of the full {\sc Majorana Demonstrator} experiment. The collaboration plans to complete the assembly of the second detector module by mid-2016 to begin full data production with the entire array., Comment: Neutrino 2016 proceeding
Published: 2016
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48. Background model for the MAJORANA DEMONSTRATOR

Author: Cuesta, C., 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., Detwiler, J. A., Dunagan, C., Efremenko, Yu., Ejiri, H., Elliott, S. R., Fullmer, A., Galindo-Uribarri, A., Gilliss, T., Giovanetti, G. K., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Henning, R., Hoppe, E. W., Howe, M. A., Jasinski, B. R., Keeter, K. J., Kidd, M. F., Konovalov, S. I., Kouzes, R. T., Leon, J., Lopez, A. M., MacMullin, J., Martin, R. D., Massarczyk, R., Meijer, S. J., Mertens, S., Orrell, J. L., O'Shaughnessy, C., Poon, A. W. P., Radford, D. C., Rager, J., Rielage, K., Robertson, R. G. H., Romero-Romero, E., 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., and Zhitnikov, I.
Subjects: Physics - Instrumentation and Detectors, Nuclear Experiment
Abstract: The MAJORANA Collaboration is constructing a system containing 44 kg of high-purity Ge (HPGe) detectors to demonstrate the feasibility and potential of a future tonne-scale experiment capable of probing the neutrino mass scale to ~15 meV. To realize this, a major goal of the MAJORANA DEMONSTRATOR is to demonstrate a path forward to achieving a background rate at or below 1 count/(ROI-t-y) in the 4 keV region of interest (ROI) around the Q-value at 2039 keV. This goal is pursued through a combination of a significant reduction of radioactive impurities in construction materials and analytical methods for background rejection, for example using powerful pulse shape analysis techniques profiting from the p-type point contact HPGe detectors technology. The effectiveness of these methods is assessed using simulations of the different background components whose purity levels are constrained from radioassay measurements. Preliminary background results obtained during the engineering runs of the Demonstrator are presented., Comment: 3 pages, 3 figures
Published: 2016
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49. The Majorana Demonstrator search for neutrinoless double beta decay

Author: Cuesta, C., Buuck, M., Detwiler, J. A., Gruszko, J., Guinn, I. S., Leon, J., Robertson, R. G. H., Abgrall, N., Bradley, A. W., Chan, Y-D., Mertens, S., Poon, A. W. P., Vetter, K., Arnquist, I. J., Hoppe, E. W., Kouzes, R. T., Orrell, J. L., Avignone III, F. T., Barabash, A. S., Konovalov, S. I., Yumatov, V., Bertrand, F. E., Galindo-Uribarri, A., Radford, D. C., Varner, R. L., Yu, C. -H., Brudanin, V., Shirchenko, M., Vasilyev, S., Yakushev, E., Zhitnikov, I., Busch, M., Caldwell, T. S., Gilliss, T., Henning, R., Howe, M. A., MacMullin, J., Meijer, S. J., O'Shaughnessy, C., Rager, J., Shanks, B., Trimble, J. E., Vorren, K., Xu, W., Christofferson, C. D., Dunagan, C., Suriano, A. M., Chu, P. -H., Elliott, S. R., Massarczyk, R., Rielage, K., White, B. R., Efremenko, Yu., Lopez, A. M., Ejiri, H., Fullmer, A., Giovanetti, G. K., Green, M. P., Guiseppe, V. E., Tedeschi, D., Wiseman, C., Jasinski, B. R., Keeter, K. J., Kidd, M. F., Martin, R. D., Romero-Romero, E., and Wilkerson, J. F.
Subjects: Physics - Instrumentation and Detectors, Nuclear Experiment
Abstract: The MAJORANA Collaboration is constructing the MAJORANA DEMONSTRATOR, an ultra-low background, modular, HPGe detector array with a mass of 44.8-kg (29.7 kg enriched >88% in Ge-76) to search for neutrinoless double beta decay in Ge-76. The next generation of tonnescale Ge-based neutrinoless double beta decay searches will probe the neutrino mass scale in the inverted-hierarchy region. The MAJORANA DEMONSTRATOR is envisioned to demonstrate a path forward to achieve a background rate at or below 1 count/tonne/year in the 4 keV region of interest around the Q-value of 2039 keV. The MAJORANA DEMONSTRATOR follows a modular implementation to be easily scalable to the next generation experiment. First data taken with the DEMONSTRATOR are introduced here., Comment: 10 pages, 4 figures, Proceedings of the XIIIth International Conference on Heavy Quarks and Leptons
Published: 2016

50. High voltage testing for 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., Byram, D., Caldwell, A. S., Chan, Y-D., Christofferson, C. D., Chu, P. -H., Cuesta, C., Detwiler, J. A., Doe, P. J., Dunagan, C., Efremenko, Yu., Ejiri, H., Elliott, S. R., Fu, Z., Galindo-Uribarri, A., Giovanetti, G. K., Goett, J., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., 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., LaFerriere, B. D., Leon, J., Li, A., MacMullin, J., Martin, R. D., Massarczyk, R., Meijer, S. J., Mertens, S., Orrell, J. L., O'Shaughnessy, C., Poon, A. W. P., Radford, D. C., Rager, J., Rielage, K., Robertson, R. G. H., Romero-Romero, E., Shanks, B., Shirchenko, M., Snyder, N., Suriano, A. M., Tedeschi, D., Thompson, A., Ton, K. T., 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., and Yumatov, V.
Subjects: Physics - Instrumentation and Detectors, High Energy Physics - Experiment, Nuclear Experiment
Abstract: The MAJORANA Collaboration is constructing the MAJORANA Demonstrator, an ultra-low background, 44-kg modular high-purity Ge (HPGe) detector array to search for neutrinoless double-beta decay in Ge-76. The phenomenon of surface micro-discharge induced by high-voltage has been studied in the context of the MAJORANA Demonstrator. This effect can damage the front-end electronics or mimic detector signals. To ensure the correct performance, every high-voltage cable and feedthrough must be capable of supplying HPGe detector operating voltages as high as 5 kV without exhibiting discharge. R&D measurements were carried out to understand the testing system and determine the optimum design configuration of the high-voltage path, including different improvements of the cable layout and feedthrough flange model selection. Every cable and feedthrough to be used at the MAJORANA Demonstrator was characterized and the micro-discharge effects during the MAJORANA Demonstrator commissioning phase were studied. A stable configuration has been achieved, and the cables and connectors can supply HPGe detector operating voltages without exhibiting discharge., Comment: 9 pages, 12 figures, 8 tables, submitted to NIM A
Published: 2016
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