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 76 Ge 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 nonlinearities. 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 nonlinearities by an order of magnitude, eliminating these as dominant contributions to the systematic energy uncertainty at the double-beta decay <inline-formula> <tex-math notation="LaTeX">Q </tex-math></inline-formula> value.
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,
08/2016, Letnik:
828
Journal Article
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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.
The MAJORANA DEMONSTRATOR is a 76Ge-based neutrinoless double-beta decay (0νββ) 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 (2νββ) of 76Ge. For Ge detectors, having superior energy resolution (0.1%), this mode poses negligible background to the 0νββ mode, even for a ton-scale experiment. However, the measurement of the 2νββ mode allows for careful systematics checks of active detector mass, enrichment fraction, and pulse shape discrimination cuts related to both the 0νββ and 2νββ decay modes. A precision measurement of the 2νββ shape also allows searches for spectral distortions, possibly indicative of new physics, including 0νββχ. Work is underway to construct a full experimental background model enabling a Bayesian fit to the measured energy spectrum and extraction of a precise 2νββ spectrum and half-life.
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.
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 detectors totaling 44.1kg (29.7kg 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 0νββ- decay search due to improvements in shielding. We discuss the statistical approaches to search for a धνββ-signal and derive the physics sensitivity for an expected exposure of 10kg· y from enriched detectors using a profile likelihood based hypothesis test in combination with toy Monte Carlo data.
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 each detectors point contact. 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.
The Majorana Collaboration has assembled an array of high purity Ge detectors to search for neutrinoless double-beta decay in 76Ge 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 76Ge) 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.
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