@article{47ae356ab758464a929ed4afd4cf8202,
title = "Radioactivity backgrounds in ZEPLIN-III",
abstract = "We examine electron and nuclear recoil backgrounds from radioactivity in the ZEPLIN-III dark matter experiment at Boulby. The rate of low-energy electron recoils in the liquid xenon WIMP target is 0.75 ± 0.05 events/kg/day/keV, which represents a 20-fold improvement over the rate observed during the first science run. Energy and spatial distributions agree with those predicted by component-level Monte Carlo simulations propagating the effects of the radiological contamination measured for materials employed in the experiment. Neutron elastic scattering is predicted to yield 3.05 ± 0.5 nuclear recoils with energy 5-50 keV per year, which translates to an expectation of 0.4 events in a 1 yr dataset in anticoincidence with the veto detector for realistic signal acceptance. Less obvious background sources are discussed, especially in the context of future experiments. These include contamination of scintillation pulses with Cherenkov light from Compton electrons and from β activity internal to photomultipliers, which can increase the size and lower the apparent time constant of the scintillation response. Another challenge is posed by multiple-scatter γ-rays with one or more vertices in regions that yield no ionisation. If the discrimination power achieved in the first run can be replicated, ZEPLIN-III should reach a sensitivity of ~1 × 10-8pb · yr to the scalar WIMP-nucleon elastic cross-section, as originally conceived.",
author = "Ara{\'u}jo, {H. M.} and Akimov, {D. Yu} and Barnes, {E. J.} and Belov, {V. A.} and A. Bewick and Burenkov, {A. A.} and V. Chepel and A. Currie and L. DeViveiros and B. Edwards and C. Ghag and A. Hollingsworth and M. Horn and Kalmus, {G. E.} and Kobyakin, {A. S.} and Kovalenko, {A. G.} and Lebedenko, {V. N.} and A. Lindote and Lopes, {M. I.} and R. L{\"u}scher and P. Majewski and Murphy, {A. St J.} and F. Neves and Paling, {S. M.} and {Pinto Da Cunha}, J. and R. Preece and Quenby, {J. J.} and L. Reichhart and Scovell, {P. R.} and C. Silva and Solovov, {V. N.} and Smith, {N. J.T.} and Smith, {P. F.} and Stekhanov, {V. N.} and Sumner, {T. J.} and C. Thorne and Walker, {R. J.}",
note = "Funding Information: The UK groups acknowledge the support of the Science & Technology Facilities Council (STFC) for the ZEPLIN-III project and for maintenance and operation of the Boulby underground laboratory. LIP-Coimbra acknowledges financial support from Funda{\c c}{\~a}o para a Ci{\^e}ncia e a Tecnologia (FCT) through project grant CERN/FP/116374/2010 and postdoctoral grants SFRH/BPD/27054/2006 , SFRH/BPD/47320/2008 and SFRH/BPD/63096/2009 . The ITEP group acknowledges support from the Russian Foundation of Basic Research (grant 08–02-91851 KO_a ) and Rosatom (contract H.4e.45.90.10.1053 from 03–02-2010). We are also grateful for support provided jointly to ITEP and Imperial from the UK Royal Society. ZEPLIN-III is hosted by Cleveland Potash Ltd (CPL) at the Boulby Mine and we thank CPL management and staff for their long-standing support. We also express our gratitude to the Boulby facility staff for their dedication. The University of Edinburgh is a charitable body registered in Scotland (SC005336).",
year = "2012",
month = mar,
doi = "10.1016/j.astropartphys.2011.11.001",
language = "English (US)",
volume = "35",
pages = "495--502",
journal = "Astroparticle Physics",
issn = "0927-6505",
publisher = "Elsevier B.V.",
number = "8",
}