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The results of studying the development of a regeneration technology for the spent alkaline electrolyte in an air–aluminum chemical power supply are presented. The application of this technology is a component of the wasteless and friendly environmental operation of an energy installation based on an air–aluminum chemical power supply. The operability of the energy installation based on the air–aluminum chemical power supply using regenerated alkaline electrolytes is experimentally confirmed. Technical requirements for the technological equipment for alkaline electrolyte regeneration are developed on the basis of the obtained results.

The Majorana Demonstrator will search for the neutrinoless double-beta (ββ0ν) decay of the isotope Ge 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.

Tagging events with the coincident detection of a barium ion would greatly reduce the background for a neutrino-less double beta decay search in xenon. This paper describes progress towards realizing this goal. It outlines a source that can produce large quantities of Ba++ in gas, shows that this can be extracted to vacuum, and demonstrates a mechanism by which the Ba++ can be efficiently converted to Ba+ as required for laser identification.

The EXO-200 experiment searched for neutrinoless double-beta decay of \\(^{136}\\)Xe with a single-phase liquid xenon detector. It used an active mass of 110 kg of 80.6%-enriched liquid xenon in an ultra-low background time projection chamber with ionization and scintillation detection and readout. This paper describes the design and performance of the various support systems necessary for detector operation, including cryogenics, xenon handling, and controls. Novel features of the system were driven by the need to protect the thin-walled detector chamber containing the liquid xenon, to achieve high chemical purity of the Xe, and to maintain thermal uniformity across the detector.

The noble elements, argon and xenon, are frequently employed as the target and event detector for weakly interacting particles such as neutrinos and Dark Matter. For such rare processes, background radiation must be carefully minimized. Radon provides one of the most significant contaminants since it is an inevitable product of trace amounts of natural uranium. To design a purification system for reducing such contamination, the adsorption characteristics of radon in nitrogen, argon, and xenon carrier gases on various types of charcoals with different adsorbing properties and intrinsic radioactive purities have been studied in the temperature range of 190-295 K at flow rates of 0.5 and 2 standard liters per minute. Essential performance parameters for the various charcoals include the average breakthrough times (\\(\\tau\\)), dynamic adsorption coefficients (k\\(_a\\)) and the number of theoretical stages (n). It is shown that the k\\(_a\\)-values for radon in nitrogen, argon, and xenon increase as the temperature of the charcoal traps decreases, and that they are significantly larger in nitrogen and argon than in xenon gas due to adsorption saturation effects. It is found that, unlike in xenon, the dynamic adsorption coefficients for radon in nitrogen and argon strictly obey the Arrhenius law. The experimental results strongly indicate that nitric acid etched Saratech is the best candidate among all used charcoal brands. It allows reducing total radon concentration in the LZ liquid Xe detector to meet the ultimate goal in the search for Dark Matter.

The LUX-ZEPLIN dark matter search aims to achieve a sensitivity to the WIMP-nucleon spin-independent cross-section down to (1--2)\\(10^-12\\)\\,pb at a WIMP mass of 40 GeV/\\(c^2\\). This paper describes the simulations framework that, along with radioactivity measurements, was used to support this projection, and also to provide mock data for validating reconstruction and analysis software. Of particular note are the event generators, which allow us to model the background radiation, and the detector response physics used in the production of raw signals, which can be converted into digitized waveforms similar to data from the operational detector. Inclusion of the detector response allows us to process simulated data using the same analysis routines as developed to process the experimental data.

LUX-ZEPLIN (LZ) is a next generation dark matter direct detection experiment that will operate 4850 feet underground at the Sanford Underground Research Facility (SURF) in Lead, South Dakota, USA. Using a two-phase xenon detector with an active mass of 7~tonnes, LZ will search primarily for low-energy interactions with Weakly Interacting Massive Particles (WIMPs), which are hypothesized to make up the dark matter in our galactic halo. In this paper, the projected WIMP sensitivity of LZ is presented based on the latest background estimates and simulations of the detector. For a 1000~live day run using a 5.6~tonne fiducial mass, LZ is projected to exclude at 90\\% confidence level spin-independent WIMP-nucleon cross sections above \\(1.4 10^-48\\)~cm\\(^2\\) for a 40~\\(GeV/c^2\\) mass WIMP. Additionally, a \\(5\\) discovery potential is projected reaching cross sections below the exclusion limits of recent experiments. For spin-dependent WIMP-neutron(-proton) scattering, a sensitivity of \\(2.3 10^-43\\)~cm\\(^2\\) (\\(7.1 10^-42\\)~cm\\(^2\\)) for a 40~\\(GeV/c^2\\) mass WIMP is expected. With underground installation well underway, LZ is on track for commissioning at SURF in 2020.

Deep underground environments are ideal for low background searches due to the attenuation of cosmic rays by passage through the earth. However, they are affected by backgrounds from \\(\\)-rays emitted by \\(^40\\)K and the \\(^238\\)U and \\(^232\\)Th decay chains in the surrounding rock. The LUX-ZEPLIN (LZ) experiment will search for dark matter particle interactions with a liquid xenon TPC located within the Davis campus at the Sanford Underground Research Facility, Lead, South Dakota, at the 4,850-foot level. In order to characterise the cavern background, in-situ \\(\\)-ray measurements were taken with a sodium iodide detector in various locations and with lead shielding. The integral count rates (0--3300~keV) varied from 596~Hz to 1355~Hz for unshielded measurements, corresponding to a total flux in the cavern of \\(1.90.4\\)~\\(~\\)cm\\(^-2\\)s\\(^-1\\). The resulting activity in the walls of the cavern can be characterised as \\(22060\\)~Bq/kg of \\(^40\\)K, \\(2915\\)~Bq/kg of \\(^238\\)U, and \\(133\\)~Bq/kg of \\(^232\\)Th.

The need for precise characterization of dual-phase xenon detectors has grown as the technology has matured into a state of high efficacy for rare event searches. The Michigan Xenon detector was constructed to study the microphysics of particle interactions in liquid xenon across a large energy range in an effort to probe aspects of radiation detection in liquid xenon. We report the design and performance of a small 3D position sensitive dual-phase liquid xenon time projection chamber with high light yield (\\(L_y^{122}=15.2 \\)pe/keV at zero field), long electron lifetime (\\(\\tau > 200 \\mu\\)s), and excellent energy resolution (\\(\\sigma/E = 1\\%\\) for 1,333 keV gamma rays in a drift field of 200 V/cm). Liquid xenon time projection chambers with such high energy resolution may find applications not only in dark matter direct detection searches, but also in neutrinoless double beta decay experiments and other applications.

The \\MJ\\ Collaboration is operating an array of high purity Ge detectors to search for neutrinoless double-beta decay in \\(^{76}\\)Ge. The \\MJ\\ \\DEM\\ comprises 44.1~kg of Ge detectors (29.7 kg enriched in \\(^{76}\\)Ge) split between two modules contained in a low background shield at the Sanford Underground Research Facility in Lead, South Dakota. Here we present results from data taken during construction, commissioning, and the start of full operations. We achieve unprecedented energy resolution of 2.5 keV FWHM at \\qval\\ and a very low background with no observed candidate events in 10 kg yr of enriched Ge exposure, resulting in a lower limit on the half-life of \\(1.9\\times10^{25}\\) yr (90\\% CL). This result constrains the effective Majorana neutrino mass to below 240 to 520 meV, depending on the matrix elements used. In our experimental configuration with the lowest background, the background is \\(4.0_{-2.5}^{+3.1}\\) counts/(FWHM t yr).