The Majorana Demonstrator radioassay program Abgrall, N.; Arnquist, I. J.; Avignone, F. T. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2016, Letnik:
828, Številka:
C
Journal Article
Recenzirano
Odprti dostop
The Majorana collaboration is constructing the Majorana Demonstrator at the Sanford Underground Research Facility at the Homestake gold mine, in Lead, SD. The apparatus will use Ge detectors, ...enriched in isotope 76Ge, to demonstrate the feasibility of a large-scale Ge detector experiment to search for neutrinoless double beta decay. The long half-life of this postulated process requires that the apparatus be extremely low in radioactive isotopes whose decays may produce backgrounds to the search. The radioassay program conducted by the collaboration to ensure that the materials comprising the apparatus are sufficiently pure is described. The resulting measurements from gamma-ray counting, neutron activation and mass spectroscopy of the radioactive-isotope contamination for the materials studied for use in the detector are reported. We interpret these numbers in the context of the expected background for the experiment.
A Dark Matter Search with MALBEK Giovanetti, G.K.; Abgrall, N.; Aguayo, E. ...
Physics procedia,
2015, 2015-00-00, 2015-01-01, Letnik:
61, Številka:
C
Journal Article
Odprti dostop
The Majorana Demonstrator is an array of natural and enriched high purity germanium detectors that will search for the neutrinoless double-beta decay of 76Ge and perform a search for weakly ...interacting massive particles (WIMPs) with masses below 10GeV. As part of the Majorana research and development efforts, we have deployed a modified, low-background broad energy germanium detector at the Kimballton Underground Research Facility. With its sub-keV energy threshold, this detector is sensitive to potential non-Standard Model physics, including interactions with WIMPs. We discuss the backgrounds present in the WIMP region of interest and explore the impact of slow surface event contamination when searching for a WIMP signal.
The MAJORANA DEMONSTRATOR will search for the neutrinoless double beta decay (ββ(0ν)) of the isotope 76Ge with a mixed array of enriched and natural germanium detectors. In view of the next ...generation of tonne-scale germanium-based ββ(0ν)-decay searches, 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 (ROI) around the 2039-keV Q-value of the 76Ge ββ(0ν)-decay. Such a requirement on the background level significantly constrains the design of the readout electronics, which is further driven by noise and energy resolution performances. We present here the low-noise low- background front-end electronics developed for the low-capacitance p-type point contact (P-PC) germanium detectors of the MAJORANA DEMONSTRATOR. This resistive-feedback front-end, specifically designed to have low mass, is fabricated on a radioassayed fused-silica substrate where the feedback resistor consists of a sputtered thin film of high purity amorphous germanium and the feedback capacitor is based on the capacitance between gold conductive traces.
The Majorana Parts Tracking Database Abgrall, N.; Aguayo, E.; Avignone, F. T. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
01/2015, Letnik:
779, Številka:
C
Journal Article
Status of the Majorana Demonstrator Cuesta, C.; Abgrall, N.; Arnquist, I. J. ...
Nuclear and particle physics proceedings,
08/2015, Letnik:
265-266, Številka:
C
Journal Article
Recenzirano
Odprti dostop
In this study, the Majorana Collaboration is constructing the Majorana Demonstrator, an ultra-low background, 40-kg modular high purity Ge detector array to search for neutrinoless double-beta decay ...in 76Ge. In view of the next generation of tonne-scale Ge-based neutrinoless double-beta decay searches that will probe the neutrino mass scale in the inverted-hierarchy region, a major goal of the Demonstrator is to demonstrate a path forward to achieving a background rate at or below 1 count/tonne/year in the 4 keV region of interest around the Q-value at 2039 keV. Lastly, the current status of the Demonstrator is discussed, as are plans for its completion.
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 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 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.
A unique way to explore the nature of the neutrino is the search for neutrinoless double beta decay (0νββ). Observation of 0νββ-decay would decisively prove that neutrinos are Majorana particles and ...that lepton number is violated. The Majorana Demonstrator will perform a search for 0νββ-decay in 76Ge. The experiment is currently under construction at the Sanford Underground Facility (SURF) in South Dakota, USA. The Majorana Demonstrator will use an array of 40 kg of high purity germanium detectors, up to 30 kg of which will be enriched to 86% in 76Ge, surrounded by passive and active shielding. The major goal is to demonstrate a path forward to achieving 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 of the 76Ge 0νββ decay. This is required for the next generation of tonne-scale germanium-based 0νββ-decay searches that are designed to probe the neutrino mass scale in the inverted-hierarchy region. Beyond the usage of ultra-clean material and extensive shielding, a key feature to achieve a low background level is a high energy resolution to minimize the ROI and pulse-shape discrimination capability to distinguish signal from background events. These properties are provided by High Purity (HP) P-type Point Contact (PPC) germanium (Ge) detectors. By enriching the natural germanium to 87% in 76Ge the detectors can be used as source and detector simultaneously. At the time of this presentation, 30 enriched detectors with average mass of 840 g have been delivered and successfully tested at SURF. All detectors met the requirements during characterization in vendor cryostat and are now being assembled in the final Majorana Demonstrator experiment.
The Majorana Collaboration is constructing a system containing 40kg 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.
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