The Majorana Demonstrator is an array of natural and enriched high purity germanium detectors that will search for the neutrinoless double-beta decay of Germanium-76 and perform a search for weakly ...interacting massive particles with masses below 10 GeV. To reach the background rate goal in the neutrinoless double-beta decay region of interest of 4 counts/keV/t/y, the DEMONSTRATOR will utilize a number of background reduction strategies, including a time-correlated event cut for 68Ge that requires a sub-keV energy threshold. This low energy threshold allows the DEMONSTRATOR to extend its physics reach to include a search for light WIMPs. We will discuss the detector systems and data analysis techniques required to achieve sub-keV thresholds as well as present the projected dark matter sensitivities of the Majorana Demonstrator.
The corporations who fund US/UK politicians want a slice of the action. 2 3 Neoliberal economists cannot comprehend public service and believe that naked greed with free markets alone offers ...salvation. Parliament is being sidelined as Lansley jumps the gun of the bill's passage and orders primary care trusts to offer up three NHS services on the altar of free market faith. 4 The experience of private finance initiative disasters, half empty independent sector treatment centres, and exploding breast implants does not shake the faith of the zealots.
Future direct searches for low-mass dark matter particles with germanium detectors, such as SuperCDMS SNOLAB, are expected to be limited by backgrounds from radioactive isotopes activated by ...cosmogenic radiation inside the germanium. There are limited experimental data available to constrain production rates and a large spread of theoretical predictions. We examine the calculation of expected production rates, and analyze data from the second run of the CDMS low ionization threshold experiment (CDMSlite) to estimate the rates for several isotopes. We model the measured CDMSlite spectrum and fit for contributions from tritium and other isotopes. Using the knowledge of the detector history, these results are converted to cosmogenic production rates at sea level. The production rates in atoms/(kg · day) are 74 ± 9 for 3H, 1.5 ± 0.7 for 55Fe, 17 ± 5 for 65Zn, and 30 ± 18 for 68Ge.
The Majorana Demonstrator calibration system Abgrall, N.; Arnquist, I.J.; Avignone III, F.T. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2017, Letnik:
872, Številka:
C
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The Majorana Collaboration is searching for the neutrinoless double-beta decay of the nucleus 76Ge. The Majorana Demonstrator is an array of germanium detectors deployed with the aim of implementing ...background reduction techniques suitable for a 1-ton 76Ge-based search. The ultra low-background conditions require regular calibrations to verify proper function of the detectors. Radioactive line sources can be deployed around the cryostats containing the detectors for regular energy calibrations. When measuring in low-background mode, these line sources have to be stored outside the shielding so they do not contribute to the background. The deployment and the retraction of the source are designed to be controlled by the data acquisition system and do not require any direct human interaction. In this paper, we detail the design requirements and implementation of the calibration apparatus, which provides the event rates needed to define the pulse-shape cuts and energy calibration used in the final analysis as well as data that can be compared to simulations.
Future ton-scale liquefied noble gas detectors depend on efficient light detection in the vacuum ultraviolet (VUV) range. In the past years, silicon photomultipliers (SiPMs) have emerged as a valid ...alternative to standard photomultiplier tubes or large-area avalanche photodiodes. The next-generation double-beta decay experiment, nEXO, with a 5-ton liquid xenon time projection chamber will use SiPMs for detecting the 175-nm xenon scintillation light, in order to achieve an energy resolution of <inline-formula> <tex-math notation="LaTeX">\boldsymbol {\sigma }/\boldsymbol {Q_{\beta \beta }} = 1 </tex-math></inline-formula>%. This paper presents recent measurements of the VUV-HD generation SiPMs from Fondazione Bruno Kessler, Trento, Italy, in two complementary setups. It includes measurements of the photon-detection efficiency (PDE) with gaseous xenon scintillation light in a vacuum setup and dark measurements in a dry nitrogen gas setup. We report improved PDE at 175 nm compared to previous generation devices that would meet the criteria of nEXO. Furthermore, we present the projected nEXO detector light collection and energy resolution that could be achieved by using these SiPMs.
We report the first measurement of the total muon flux underground at the Davis Campus of the Sanford Underground Research Facility at the 4850 ft level. Measurements were performed using the ...MajoranaDemonstrator muon veto system arranged in two different configurations. The measured total flux is (5.31±0.17)×10−9μ/s/cm2.
The Majorana Demonstrator will search for the neutrinoless double-beta (ββ0ν) decay of the isotope 76Ge with a mixed array of enriched and natural germanium detectors. The observation of this rare ...decay would indicate that the neutrino is its own antiparticle, demonstrate that lepton number is not conserved, and provide information on the absolute mass scale of the neutrino. The Demonstrator is being assembled at the 4850-foot level of the Sanford Underground Research Facility in Lead, South Dakota. The array will be situated in a low-background environment and surrounded by passive and active shielding. Here we describe the science goals of the Demonstrator and the details of its design.
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