The Majorana Demonstrator: A Search for Neutrinoless Double-beta Decay of 76Ge (1501.03089)
Majorana Collaboration: W. Xu, N. Abgrall, F. T. Avignone III, A. S. Barabash, F. E. Bertrand, V. Brudanin, M. Busch, M. Buuck, D. Byram, A.S. Caldwell, Y-D. Chan, C. D. Christofferson, C. Cuesta, J. A. Detwiler, Yu. Efremenko, H. Ejiri, S. R. Elliott, A. Galindo-Uribarri, G. K. Giovanetti, J. Goett, M. P. Green, J. Gruszko, I. Guinn, V. E. Guiseppe, R. Henning, E. W. Hoppe, S. Howard, M. A. Howe, B. R. Jasinski, K. J. Keeter, M. F. Kidd, S. I. Konovalov, R. T. Kouzes, B. D. LaFerriere, J. Leon, J. MacMullin, R. D. Martin, S. J. Meijer, S. Mertens, J. L. Orrell, C. O'Shaughnessy, N. R. Overman, A. W. P. Poon, D. C. Radford, J. Rager, K. Rielage, R. G. H. Robertson, E. Romero-Romero, M. C. Ronquest, B. Shanks, M. Shirchenko, N. Snyder, A. M. Suriano, D. Tedeschi, J. E. Trimble, R. L. Varner, S. Vasilyev, K. Vetter, K. Vorren, B. R. White, J. F. Wilkerson, C. Wiseman, E. Yakushev, C-H. Yu, V. Yumatov
May 9, 2015 nucl-ex, physics.ins-det
Neutrinoless double-beta decay is a hypothesized process where in some even-even nuclei it might be possible for two neutrons to simultaneously decay into two protons and two electrons without emitting neutrinos. This is possible only if neutrinos are Majorana particles, i.e. fermions that are their own antiparticles. Neutrinos being Majorana particles would explicitly violate lepton number conservation, and might play a role in the matter-antimatter asymmetry in the universe. The observation of neutrinoless double-beta decay would also provide complementary information related to neutrino masses. The Majorana Collaboration is constructing the Majorana Demonstrator, a 40-kg modular germanium detector array, to search for the Neutrinoless double-beta decay of 76Ge and to demonstrate a background rate at or below 3 counts/(ROI-t-y) in the 4 keV region of interest (ROI) around the 2039 keV Q-value for 76Ge Neutrinoless double-beta decay. In this paper, we discuss the physics of neutrinoless double beta decay and then focus on the Majorana Demonstrator, including its design and approach to achieve ultra-low backgrounds and the status of the experiment.
Low Background Signal Readout Electronics for the MAJORANA DEMONSTRATOR (1502.03174)
I. Guinn, N. Abgrall, F. T. Avignone III, A. S. Barabash, F. E. Bertrand, V. Brudanin, M. Busch, M. Buuck, D. Byram, A.S. Caldwell, Y-D. Chan, C. D. Christofferson, C. Cuesta, J. A. Detwiler, Yu. Efremenko, H. Ejiri, S. R. Elliott, A. Galindo-Uribarri, G. K. Giovanetti, J. Goett, M. P. Green, J. Gruszko, V. E. Guiseppe, R. Henning, E. W. Hoppe, S. Howard, M. A. Howe, B. R. Jasinski, K. J. Keeter, M. F. Kidd, S. I. Konovalov, R. T. Kouzes, B. D. LaFerriere, J. Leon, J. MacMullin, R. D. Martin, S. J. Meijer, S. Mertens, J. L. Orrell, C. O'Shaughnessy, N. R. Overman, A. W. P. Poon, D. C. Radford, J. Rager, K. Rielage, R. G. H. Robertson, E. Romero-Romero, M. C. Ronquest, B. Shanks, M. Shirchenko, N. Snyder, A. M. Suriano, D. Tedeschi, J. E. Trimble, R. L. Varner, S. Vasilyev, K. Vetter, K. Vorren, B. R. White, J. F. Wilkerson, C. Wiseman, W. Xu, E. Yakushev, C-H. Yu, V. Yumatov
Feb. 11, 2015 nucl-ex, physics.ins-det
The MAJORANA DEMONSTRATOR is a planned 40 kg array of Germanium detectors intended to demonstrate the feasibility of constructing a tonne-scale experiment that will seek neutrinoless double beta decay ($0\nu\beta\beta$) in $^{76}\mathrm{Ge}$. Such an experiment would require backgrounds of less than 1 count/tonne-year in the 4 keV region of interest around the 2039 keV Q-value of the $\beta\beta$ decay. Designing low-noise electronics, which must be placed in close proximity to the detectors, presents a challenge to reaching this background target. This paper will discuss the MAJORANA collaboration's solutions to some of these challenges.
MAJORANA Collaboration's Experience with Germanium Detectors (1502.01742)
S. Mertens, N. Abgrall, F. T. Avignone III, A. S. Barabash, F. E. Bertrand, V. Brudanin, M. Busch, M. Buuck, D. Byram, A.S. Caldwell, Y-D. Chan, C. D. Christofferson, C. Cuesta, J. A. Detwiler, Yu. Efremenko, H. Ejiri, S. R. Elliott, A. Galindo-Uribarri, G. K. Giovanetti, J. Goett, M. P. Green, J. Gruszko, I. Guinn, V. E. Guiseppe, R. Henning, E. W. Hoppe, S. Howard, M. A. Howe, B. R. Jasinski, K. J. Keeter, M. F. Kidd, S. I. Konovalov, R. T. Kouzes, B. D. LaFerriere, J. Leon, J. MacMullin, R. D. Martin, S. J. Meijer, J. L. Orrell, C. O'Shaughnessy, N. R. Overman, A. W. P. Poon, D. C. Radford, J. Rager, K. Rielage, R. G. H. Robertson, E. Romero-Romero, M. C. Ronquest, B. Shanks, M. Shirchenko, N. Snyder, A. M. Suriano, D. Tedeschi, J. E. Trimble, R. L. Varner, S. Vasilyev, K. Vetter, K. Vorren, B. R. White, J. F. Wilkerson, C. Wiseman, W. Xu, E. Yakushev, C-H. Yu, V. Yumatov
Feb. 5, 2015 nucl-ex, physics.ins-det
The goal of the \textsc{Majorana} \textsc{Demonstrator} project is to search for 0$\nu\beta\beta$ decay in $^{76}\mathrm{Ge}$. Of all candidate isotopes for 0$\nu\beta\beta$, $^{76}\mathrm{Ge}$ has some of the most favorable characteristics. Germanium detectors are a well established technology, and in searches for 0$\nu\beta\beta$, the high purity germanium crystal acts simultaneously as source and detector. Furthermore, p-type germanium detectors provide excellent energy resolution and a specially designed point contact geometry allows for sensitive pulse shape discrimination. This paper will summarize the experiences the \textsc{Majorana} collaboration made with enriched germanium detectors manufactured by ORTEC$^{\circledR}$. The process from production, to characterization and integration in \textsc{Majorana} mounting structure will be described. A summary of the performance of all enriched germanium detectors will be given.
The Majorana Parts Tracking Database (1502.01748)
The Majorana Collaboration: N. Abgrall, F. T. Avignone III, V. Brudanin, Y-D. Chan, J. A. Detwiler, H. Ejiri, P. Finnerty, G. K. Giovanetti, V. E. Guiseppe, A. Hegai, M. A. Howe (8, 20), K. J. Keeter, S. I. Konovalov, L. E. Leviner, R. D. Martin, L. Mizouni, N. R. Overman, A. W. P. Poon, K. Rielage, M. C. Ronquest, K. J. Snavely, D. Tedeschi, J. E. Trimble, K. Vorren, C. Wiseman, C.-H. Yu Black Hills State University, Institute for Theoretical, Experimental Physics, Lawrence Berkeley National Laboratory, Center for Experimental Nuclear Physics, Astrophysics, University of Washington, North Carolina State University, Osaka University, Tennessee Tech University, Shanghai Jiao Tong University, University of South Dakota, Triangle Universities Nuclear Laboratory)
The Majorana Demonstrator is an ultra-low background physics experiment searching for the neutrinoless double beta decay of $^{76}$Ge. The Majorana Parts Tracking Database is used to record the history of components used in the construction of the Demonstrator. The tracking implementation takes a novel approach based on the schema-free database technology CouchDB. Transportation, storage, and processes undergone by parts such as machining or cleaning are linked to part records. Tracking parts provides a great logistics benefit and an important quality assurance reference during construction. In addition, the location history of parts provides an estimate of their exposure to cosmic radiation. A web application for data entry and a radiation exposure calculator have been developed as tools for achieving the extreme radio-purity required for this rare decay search.
Background Model for the Majorana Demonstrator (1405.1370)
C. Cuesta, N. Abgrall, E. Aguayo, F.T. Avignone III, A. S. Barabash, F. E. Bertrand, M. Boswell, V. Brudanin, M. Busch, D. Byram, A. S. Caldwell, Y-D. Chan, C. D. Christofferson, D. C. Combs, C. Cuesta, J. A. Detwiler, P. J. Doe, Yu. Efremenko, V. Egorov, H. Ejiri, S. R. Elliott, J. E. Fast, P. Finnerty, F. M. Fraenkle, A. Galindo-Uribarri, G. K. Giovanetti, J. Goett, M. P. Green, J. Gruszko, V. E. Guiseppe, K. Gusev, A. L. Hallin, R. Hazama, A. Hegai, R. Henning, E. W. Hoppe, S. Howard, M. A. Howe, K. J. Keeter, M.F. Kidd, O. Kochetov, S. I. Konovalov, R. T. Kouzes, B. D. LaFerriere, J. Leon, L. E. Leviner, J. C. Loach, J. MacMullin, S. MacMullin, R.D. Martin, S. Meijer, S. Mertens, M. Nomachi, J. L. Orrell, C. O'Shaughnessy, N. R. Overman, D. G. Phillips II, A. W.P. Poon, K. Pushkin, D. C. Radford, J. Rager, K. Rielage, R. G. H. Robertson, E. Romero-Romero, M.C. Ronquest, A.G. Schubert, B. Shanks, T. Shima, M. Shirchenko, K. J. Snavely, N. Snyder, A. M. Suriano, J. Thompson, V. Timkin, W. Tornow, J. E. Trimble, R. L. Varner, S. Vasilyev, K. Vetter, K. Vorren, B. R. White, J. F. Wilkerson, C. Wiseman, W. Xu, E. Yakushev, A. R. Young, C. H. Yu, V. Yumatov
The Majorana Collaboration is constructing a system containing 40 kg of HPGe detectors to demonstrate the feasibility and potential of a future tonne-scale experiment capable of probing the neutrino mass scale in the inverted-hierarchy region. 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 cnt/(ROI-t-y) in the 4 keV region of interest around the Q-value at 2039 keV. This goal is pursued through a combination of a significant reduction of radioactive impurities in construction materials with 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.
Testing the Ge detectors for the MAJORANA DEMONSTRATOR (1404.7399)
W. Xu, N. Abgrall, E. Aguayo, F.T. Avignone III, A. S. Barabash, F. E. Bertrand, M. Boswell, V. Brudanin, M. Busch, D. Byram, A. S. Caldwell, Y-D. Chan, C. D. Christofferson, D. C. Combs, C. Cuesta, J. A. Detwiler, P. J. Doe, Yu. Efremenko, V. Egorov, H. Ejiri, S. R. Elliott, J. E. Fast, P. Finnerty, F. M. Fraenkle, A. Galindo-Uribarri, G. K. Giovanetti, J. Goett, M. P. Green, J. Gruszko, V. E. Guiseppe, K. Gusev, A. L. Hallin, R. Hazama, A. Hegai, R. Henning, E. W. Hoppe, S. Howard, M. A. Howe, K. J. Keeter, M.F. Kidd, O. Kochetov, S. I. Konovalov, R. T. Kouzes, B. D. LaFerriere, J. Leon, L. E. Leviner, J. C. Loach, J. MacMullin, S. MacMullin, R.D. Martin, S. Meijer, S. Mertens, M. Nomachi, J. L. Orrell, C. O'Shaughnessy, N. R. Overman, D. G. Phillips II, A. W.P. Poon, K. Pushkin, D. C. Radford, J. Rager, K. Rielage, R. G. H. Robertson, E. Romero-Romero, M.C. Ronquest, A.G. Schubert, B. Shanks, T. Shima, M. Shirchenko, K. J. Snavely, N. Snyder, A. M. Suriano, J. Thompson, V. Timkin, W. Tornow, J. E. Trimble, R. L. Varner, S. Vasilyev, K. Vetter, K. Vorren, B. R. White, J. F. Wilkerson, C. Wiseman, E. Yakushev, A. R. Young, C. H. Yu, V. Yumatov
April 29, 2014 nucl-ex, physics.ins-det
High purity germanium (HPGe) crystals will be used for the MAJORANA DEMONSTRATOR, where they serve as both the source and the detector for neutrinoless double beta decay. It is crucial for the experiment to understand the performance of the HPGe crystals. A variety of crystal properties are being investigated, including basic properties such as energy resolution, efficiency, uniformity, capacitance, leakage current and crystal axis orientation, as well as more sophisticated properties, e.g. pulse shapes and dead layer and transition layer distributions. In this paper, we will present our measurements that characterize the HPGe crystals. We will also discuss our simulation package for the detector characterization setup, and show that additional information can be extracted from data-simulation comparisons.