29 research outputs found
The LUX-ZEPLIN (LZ) Experiment
We describe the design and assembly of the LUX-ZEPLIN experiment, a direct detection search for cosmic WIMP dark matter particles. The centerpiece of the experiment is a large liquid xenon time projection chamber sensitive to low energy nuclear recoils. Rejection of backgrounds is enhanced by a Xe skin veto detector and by a liquid scintillator Outer Detector loaded with gadolinium for efficient neutron capture and tagging. LZ is located in the Davis Cavern at the 4850' level of the Sanford Underground Research Facility in Lead, South Dakota, USA. We describe the major subsystems of the experiment and its key design features and requirements
The LUX-ZEPLIN (LZ) radioactivity and cleanliness control programs
LUX-ZEPLIN (LZ) is a second-generation direct dark matter experiment with spin-independent WIMP-nucleon scattering sensitivity above 1.4×10−48cm2 for a WIMP mass of 40GeV/c2 and a 1000days exposure. LZ achieves this sensitivity through a combination of a large 5.6t fiducial volume, active inner and outer veto systems, and radio-pure construction using materials with inherently low radioactivity content. The LZ collaboration performed an extensive radioassay campaign over a period of six years to inform material selection for construction and provide an input to the experimental background model against which any possible signal excess may be evaluated. The campaign and its results are described in this paper. We present assays of dust and radon daughters depositing on the surface of components as well as cleanliness controls necessary to maintain background expectations through detector construction and assembly. Finally, examples from the campaign to highlight fixed contaminant radioassays for the LZ photomultiplier tubes, quality control and quality assurance procedures through fabrication, radon emanation measurements of major sub-systems, and bespoke detector systems to assay scintillator are presented
Interface phenomena at semiconductor heterojunctions: Local-Density valence-band offset in GaAs/AlAs
The effect of sub-clinical infection with Mycobacterium avium subsp. paratuberculosis on milk production in a New Zealand dairy herd
Unusual Angiographic Changes in an Internal Carotid Artery Pseudoaneurysm After Infection in the Deep Neck Space -Case Report-
Varicocele
Varicocele is clinically defined as an abnormal dilatation of the veins of the pampiniform plexus with continuous or intermittent reflux of the venous blood. It is actually considered the most common correctable cause of male infertility, even though the mechanisms responsible for infertility are still unclear. The prevalence of this disorder in the general population is approximately 15\u201320 % [1], and it is involved in up to 40 % of cases of men infertility [2\u20134]