Initial Results from the MAJORANA DEMONSTRATOR

S. R. Elliott, N. Abgrall, I. J. Arnquist, F. T. Avignone III, A. S. Barabash, F. E. Bertrand, A. W. Bradley, V. Brudanin, M. Busch, M. Buuck, T. S. Caldwell, Y-D. Chan, C. D. Christofferson, P. -H. Chu, C. Cuesta, J. A. Detwiler, C. Dunagan, Yu. Efremenko, H. Ejiri, A. Fullmer, A. Galindo-Uribarri, T. Gilliss, G. K. Giovanetti, M. P. Green, J. Gruszko, I. S. Guinn, V. E. Guiseppe, R. Henning, E. W. Hoppe, M. A. Howe, B. R. Jasinski, K. J. Keeter, M. F. Kidd, S. I. Konovalov, R. T. Kouzes, J. Leon, A. M. Lopez, J. MacMullin, R. D. Martin, R. Massarczyk, S. J. Meijer, S. Mertens, J. L. Orrell, C. O'Shaughnessy, A. W. P. Poon, D. C. Radford, J. Rager, K. Rielage, R. G. H. Robertson, E. Romero-Romero, B. Shanks, M. Shirchenko, 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, I. Zhitnikov

Published 2016-10-04Version 1

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.