Candidates for Inelastic Dark Matter

Although we have yet to determine whether the DAMA data represents a true discovery of new physics, among such interpretations inelastic dark matter (IDM) can match the energy spectrum of DAMA very well while not contradicting the results of other direct detection searches. In this paper we investigate the general properties that a viable IDM candidate must have and search for simple models that realize these properties in natural ways. We begin by determining the regions of IDM parameter space that are allowed by direct detection searches including DAMA, paying special attention to larger IDM masses. We observe that an inelastic dark matter candidate with electroweak interactions can naturally satisfy observational constraints while simultaneously yielding the correct thermal relic abundance. We comment on several other proposed dark matter explanations for the DAMA signal and demonstrate that one of the proposed alternatives -- elastic scattering of dark matter off electrons -- is strongly disfavored when the modulated and unmodulated DAMA spectral data are taken into account. We then outline the general essential features of IDM models in which inelastic scattering off nuclei is mediated by the exchange of a massive gauge boson, and construct natural models in the context of a warped extra dimension and supersymmetry.Comment: 44 pages, 6 figures, added reference

Adhesion of dental cements to zirconia restorations. Part 2 [Adgeziya tsementov k keramicheskim zubnym protezam iz dioksida tsirkoniya. Chast' 2]

The information about methods of surface preparation for dentures made from ceramic based on zirconium dioxide for better adhesive fixation is presented in the first part of this article. Micromechanical methods of preparation for cementation of the surface of a zirconia dental prosthesis are discussed in the first part of this article. The second part of the article provides an overview of scientific research on chemical methods for preparing a surface made of zirconia and the problem of the bond strength of polymer cement with a prepared surface made of zirconia.В первой части нашей статьи была изложена информация о механических методах подготовки поверхности зубных протезов из стоматологической керамики на основе диоксида циркония для получения наилучшей адгезионной прочности. Во второй части представлен обзор научных исследований, посвященных химическим методам подготовки поверхности диоксида циркония и проблеме долговечности связи между полимерным цементом и подготовленной поверхностью диоксида циркония

Identification of radiopure titanium for the LZ dark matter experiment and future rare event searches

The LUX-ZEPLIN (LZ) experiment will search for dark matter particle interactions with a detector containing a total of 10 tonnes of liquid xenon within a double-vessel cryostat. The large mass and proximity of the cryostat to the active detector volume demand the use of material with extremely low intrinsic radioactivity. We report on the radioassay campaign conducted to identify suitable metals, the determination of factors limiting radiopure production, and the selection of titanium for construction of the LZ cryostat and other detector components. This titanium has been measured with activities of 238Ue  < 1.6 mBq/kg, 238Ul  < 0.09 mBq/kg, 232The=0.28±0.03 mBq/kg, 232Thl=0.25±0.02 mBq/kg, 40K  < 0.54 mBq/kg, and 60Co  < 0.02 mBq/kg (68% CL). Such low intrinsic activities, which are some of the lowest ever reported for titanium, enable its use for future dark matter and other rare event searches. Monte Carlo simulations have been performed to assess the expected background contribution from the LZ cryostat with this radioactivity. In 1,000 days of WIMP search exposure of a 5.6-tonne fiducial mass, the cryostat will contribute only a mean background of 0.160 ± 0.001(stat) ± 0.030(sys) counts