WIMP-nucleon cross-section results from the second science run of ZEPLIN-III

We report experimental upper limits on WIMP-nucleon elastic scattering cross sections from the second science run of ZEPLIN-III at the Boulby Underground Laboratory. A raw fiducial exposure of 1,344 kg.days was accrued over 319 days of continuous operation between June 2010 and May 2011. A total of eight events was observed in the signal acceptance region in the nuclear recoil energy range 7-29 keV, which is compatible with background expectations. This allows the exclusion of the scalar cross-section above 4.8E-8 pb near 50 GeV/c^2 WIMP mass with 90% confidence. Combined with data from the first run, this result improves to 3.9E-8 pb. The corresponding WIMP-neutron spin-dependent cross-section limit is 8.0E-3 pb. The ZEPLIN programme reaches thus its conclusion at Boulby, having deployed and exploited successfully three liquid xenon experiments of increasing reach

The ZEPLIN-III dark matter detector: instrument design, manufacture and commissioning

We present details of the technical design and manufacture of the ZEPLIN-III dark matter experiment. ZEPLIN-III is a two-phase xenon detector which measures both the scintillation light and the ionisation charge generated in the liquid by interacting particles and radiation. The instrument design is driven by both the physics requirements and by the technology requirements surrounding the use of liquid xenon. These include considerations of key performance parameters, such as the efficiency of scintillation light collection, restrictions placed on the use of materials to control the inherent radioactivity levels, attainment of high vacuum levels and chemical contamination control. The successful solution has involved a number of novel design and manufacturing features which will be of specific use to future generations of direct dark matter search experiments as they struggle with similar and progressively more demanding requirements.Comment: 25 pages, 19 figures. Submitted to Astropart. Phys. Some figures down sampled to reduce siz

СОВРЕМЕННОЕ СОСТОЯНИЕ И ПЕРСПЕКТИВЫ ДИАГНОСТИКИ НОЗОКОМИАЛЬНОЙ ПНЕВМОНИИ У ПОСТРАДАВШИХ ПРИ ПОЛИТРАВМЕ

Trauma injuries account for high mortality and disability in the cohort of the employable population. Pulmonary infectious complications in those injured with multiple traumas contribute the most to mortality of such patients. The article describes risk factors, causative agents, pathologic physiology and specific features of diagnostics of nosocomial pneumonia in those with multiple traumas. Special attention is paid to study of state and variants of the immune response to multiple trauma and related issues on using polymorphism of genes controlling the release of certain cytokines in order to improve diagnostics and prognosis of the course and outcome of nosocomial pneumonia in this group of patients. Травматические повреждения определяют высокий уровень смертности и инвалидности в когорте трудоспособного населения. Легочные инфекционные осложнения у пострадавших при политравме вносят наибольший вклад в показатели летальности у пациентов данной группы. В статье рассмотрены факторы риска, возбудители, патофизиология и особенности диагностики нозокомиальной пневмонии у пострадавших при политравме. Отдельно изучены состояние и варианты иммунного ответа организма на политравму, а также связанные с этим вопросы возможности использования данных о полиморфизме генов цитокинов для улучшения диагностики и оценки прогноза течения и исхода нозокомиальной пневмонии у пациентов данной группы.

Performance data from the ZEPLIN-III second science run

ZEPLIN-III is a two-phase xenon direct dark matter experiment located at the Boulby Mine (UK). After its first science run in 2008 it was upgraded with: an array of low background photomultipliers, a new anti-coincidence detector system with plastic scintillator and an improved calibration system. After 319 days of data taking the second science run ended in May 2011. In this paper we describe the instrument performance with emphasis on the position and energy reconstruction algorithm and summarise the final science results.Comment: Submitted to PSD9 conference proceeding

Position Reconstruction in a Dual Phase Xenon Scintillation Detector

We studied the application of statistical reconstruction algorithms, namely maximum likelihood and least squares methods, to the problem of event reconstruction in a dual phase liquid xenon detector. An iterative method was developed for in-situ reconstruction of the PMT light response functions from calibration data taken with an uncollimated gamma-ray source. Using the techniques described, the performance of the ZEPLIN-III dark matter detector was studied for 122 keV gamma-rays. For the inner part of the detector (R<100 mm), spatial resolutions of 13 mm and 1.6 mm FWHM were measured in the horizontal plane for primary and secondary scintillation, respectively. An energy resolution of 8.1% FWHM was achieved at that energy. The possibility of using this technique for improving performance and reducing cost of scintillation cameras for medical applications is currently under study.Comment: 8 pages, 7 figures, in the Conference Record of IEEE NSS 2011, accepted for publication in IEEE Trans. on Nuc. Sc