► DRIFT is only one of a handful of directional dark matter detectors. ► A method of rejecting Radon Progeny Recoils, DRIFT’s main background, is discussed. ► Additionally DRIFT-IId was found to run ...stably with a mixture of CS2 and CF4. ► DRIFT’s sensitivity is orders of magnitude better than other directional detectors.
Data are presented from the DRIFT-IId detector operated in the Boulby Underground Science Facility in England. A 0.8m3 fiducial volume, containing partial pressures of 30Torr CS2 and 10Torr CF4, was exposed for a duration of 47.4 live-time days with sufficient passive shielding to provide a neutron free environment within the detector. The nuclear recoil events seen are consistent with a remaining low-level background from the decay of radon daughters attached to the central cathode of the detector. However, charge from such events must drift across the entire width of the detector, and thus display large diffusion upon reaching the readout planes of the device. Exploiting this feature, it is shown to be possible to reject energy depositions from these Radon Progeny Recoil events while still retaining sensitivity to fiducial-volume nuclear recoil events. The response of the detector is then interpreted, using the F nuclei content of the gas, in terms of sensitivity to proton spin-dependent WIMP–nucleon interactions, displaying a minimum in sensitivity cross section at 1.8pb for a WIMP mass of 100GeV/c2. This sensitivity was achieved without compromising the direction sensitivity of DRIFT.
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.
We report the observation of two-neutrino double-beta decay in (136)Xe with T(1/2) = 2.11 ± 0.04(stat) ± 0.21(syst) × 10(21) yr. This second-order process, predicted by the standard model, has been ...observed for several nuclei but not for (136)Xe. The observed decay rate provides new input to matrix element calculations and to the search for the more interesting neutrinoless double-beta decay, the most sensitive probe for the existence of Majorana particles and the measurement of the neutrino mass scale.
Study of radon reduction in gases for rare event search experiments Pushkin, K.; Akerlof, C.; Anbajagane, D. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2018, Letnik:
903, Številka:
C
Journal Article
Recenzirano
Odprti dostop
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 (τ), dynamic adsorption coefficients (ka) and the number of theoretical stages (n). It is shown that the ka-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.
A new γ-ray imaging camera based on High-pressure Xe Time-Projection-Chamber (HPXe-TPC) allows us to simultaneously determine arrival direction and its energy of individual incident γ rays. HPXe-TPC ...is a promising γ-ray detector for planetary science which provides means of global mapping of elemental composition in planetary surface as the remote sensing spectrometer. The simulation study by Geant4 and numerical calculation show that the angular resolution is mostly affected by multiple scattering of the recoil electron, and position resolution of electrodes of TPC. It is found that the angular resolution is 9° (50%) at 2
MeV for γ rays. The feasibility of HPXe-TPC is discussed as a γ-ray imaging camera for future planetary mission.
The current status of the DRIFT (Directional Recoil Identification From Tracks) experiment at Boulby Mine is presented, including the latest limits on the WIMP spin-dependent cross-section from 1.5 ...kg days of running with a mixture of CS2 and CF4. Planned upgrades to DRIFT IId are detailed, along with ongoing work towards DRIFT III, which aims to be the world’s first 10 m3-scale directional Dark Matter detector.
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.
Scintillation light, ionization yield and scintillation decay times have been measured in xenon and in its mixture with a 0.05% concentration of methane as a function of the reduced electric field ...(E/N)-the ratio of the electric field strength to the number density of gas-at a pressure of 21 atm. The measurements of scintillation decay times in the xenon-methane mixture have been made for the first time as a function of the reduced electric field (E/N). An ionization chamber has been constructed to simultaneously measure electrons and photons from a 239 Pu source, which is placed in the center of a cathode in the chamber. The main peculiarity of the chamber is a movable cathode to measure scintillation light and ionization yield at various distances from the anode and monitor the purity of the investigated gas. It has been observed that both scintillation light and ionization yield decrease when methane is added into the xenon gas. Scintillation decay times in the xenon-methane mixture are observed to be longer than in the pure xenon when the electric field strength increases.
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