The Majorana Demonstrator: A Search for Neutrinoless Double-beta Decay of 76Ge

2nd Workshop on Germanium Detectors and Technologies

Xu, W.^1 ; Abgrall, N.^2 ; Avignone, F.T.^3,4 ; Barabash, A.S.^5 ; Bertrand, F.E.^4 ; Brudanin, V.^6 ; Busch, M.^7,8 ; Buuck, M.^9 ; Byram, D.^10 ; Caldwell, A.S.^11 ; Chan, Y.-D.^2 ; Christofferson, C.D.^11 ; Cuesta, C.^9 ; Detwiler, J.A.^9 ; Efremenko, Yu^12 ; Ejiri, H.^13 ; Elliott, S.R.^1 ; Galindo-Uribarri, A.^4 ; Giovanetti, G.K.^8,14 ; Goett, J.^1 ; Green, M.P.^4 ; Gruszko, J.^9 ; Guinn, I.^9 ; Guiseppe, V.E.^3 ; Henning, R.^8,14 ; Hoppe, E.W.^15 ; Howard, S.^11 ; Howe, M.A.^8,14 ; Jasinski, B.R.^10 ; Keeter, K.J.^16 ; Kidd, M.F.^17 ; Konovalov, S.I.^5 ; Kouzes, R.T.^15 ; Laferriere, B.D.^15 ; Leon, J.^9 ; Macmullin, J.^8,14 ; Martin, R.D.^10 ; Meijer, S.J.^8,14 ; Mertens, S.^2 ; Orrell, J.L.^15 ; O'Shaughnessy, C.^8,14 ; Overman, N.R.^15 ; Poon, A.W.P.^2 ; Radford, D.C.^4 ; Rager, J.^8,14 ; Rielage, K.^1 ; Robertson, R.G.H.^9 ; Romero-Romero, E.^4,12 ; Ronquest, M.C.^1 ; Shanks, B.^8,14 ; Shirchenko, M.^6 ; Snyder, N.^10 ; Suriano, A.M.^11 ; Tedeschi, D.^3 ; Trimble, J.E.^8,14 ; Varner, R.L.^4 ; Vasilyev, S.^6 ; Vetter, K.^2,18 ; Vorren, K.^8,14 ; White, B.R.^4 ; Wilkerson, J.F.^4,8,14 ; Wiseman, C.^3 ; Yakushev, E.^6 ; Yu, C.-H.^4 ; Yumatov, V.^5

Los Alamos National Laboratory, Los Alamos

NM, United States^1

Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley

CA, United States^2

Department of Physics and Astronomy, University of South Carolina, Columbia

SC, United States^3

Oak Ridge National Laboratory, Oak Ridge

TN, United States^4

Institute for Theoretical and Experimental Physics, Moscow, Russia^5

Joint Institute for Nuclear Research, Dubna, Russia^6

Department of Physics, Duke University, Durham

NC, United States^7

Triangle Universities Nuclear Laboratory, Durham

NC, United States^8

Center for Experimental Nuclear Physics and Astrophysics, Department of Physics, University of Washington, Seattle

WA, United States

(10) Department of Physics, University of South Dakota, Vermillion

SD, United States

(11) South Dakota School of Mines and Technology, Rapid City

SD, United States

(12) Department of Physics and Astronomy, University of Tennessee, Knoxville

TN, United States

(13) Research Center for Nuclear Physics, Department of Physics, Osaka University, Ibaraki, Osaka, Japan

(14) Department of Physics and Astronomy, University of North Carolina, Chapel Hill

NC, United States

(15) Pacific Northwest National Laboratory, Richland

WA, United States

(16) Department of Physics, Black Hills State University, Spearfish

SD, United States

(17) Tennessee Tech University, Cookeville

TN, United States

(18) Department of Nuclear Engineering, University of California, Berkeley

CA, United States^9

关键词: Even-even nuclei;    Germanium detector;    Lepton number;    Majorana particles;    Neutrino mass;    Neutrinoless double-beta decays;    Region of interest;    Ultra low backgrounds;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/606/1/012004/pdf
DOI  :  10.1088/1742-6596/606/1/012004

来源: IOP

【 摘 要 】

Neutrinoless double-beta (0νββ) 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, with a total of 40-kg Germanium detectors, to search for the 0νββ decay of76Ge 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 for76Ge 0νββ 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.