eprintid: 1352150 rev_number: 30 eprint_status: archive userid: 608 dir: disk0/01/35/21/50 datestamp: 2012-07-04 18:43:47 lastmod: 2021-09-20 00:29:08 status_changed: 2018-06-05 13:08:04 type: article metadata_visibility: show item_issues_count: 0 creators_name: Alner, GJ creators_name: Araujo, HM creators_name: Bewick, A creators_name: Bungau, C creators_name: Camanzi, B creators_name: Carson, MJ creators_name: Cashmore, RJ creators_name: Chagani, H creators_name: Chepel, V creators_name: Cline, D creators_name: Davidge, D creators_name: Davies, JC creators_name: Daw, E creators_name: Dawson, J creators_name: Durkin, T creators_name: Edwards, B creators_name: Gamble, T creators_name: Gao, J creators_name: Ghag, C creators_name: Howard, AS creators_name: Jones, WG creators_name: Joshi, M creators_name: Korolkova, EV creators_name: Kudryavtsev, VA creators_name: Lawson, T creators_name: Lebedenko, VN creators_name: Lewin, JD creators_name: Lightfoot, P creators_name: Lindote, A creators_name: Liubarsky, I creators_name: Lopes, MI creators_name: Luescher, R creators_name: Majewski, P creators_name: Mavrokoridis, K creators_name: McMillan, JE creators_name: Morgan, B creators_name: Muna, D creators_name: Murphy, ASJ creators_name: Neves, F creators_name: Nicklin, GG creators_name: Ooi, W creators_name: Paling, SM creators_name: da Cunha, JP creators_name: Plank, SJS creators_name: Preece, RM creators_name: Quenby, JJ creators_name: Robinson, M creators_name: Salinas, G creators_name: Sergiampietri, F creators_name: Silva, C creators_name: Solovov, VN creators_name: Smith, NJT creators_name: Smith, PF creators_name: Spooner, NJC creators_name: Sumner, TJ creators_name: Thorne, C creators_name: Tovey, DR creators_name: Tziaferi, E creators_name: Walker, RJ creators_name: Wang, H creators_name: White, JT creators_name: Wolfs, FLH title: First limits on WIMP nuclear recoil signals in ZEPLIN-II: A two-phase xenon detector for dark matter detection ispublished: pub divisions: UCL divisions: B04 divisions: C06 divisions: F60 keywords: Science & Technology, Physical Sciences, Astronomy & Astrophysics, Physics, Particles & Fields, Physics, astronomy & astrophysics, physics, particles & fields, zeplin-ii, dark matter, WIMPs, liquid xenon, radiation detectors, liquid xenon, scintillation efficiency, energy, electrons, argon note: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. abstract: Results are presented from the first underground data run of ZEPLIN-II, a 31 kg two-phase xenon detector developed to observe nuclear recoils from hypothetical weakly interacting massive dark matter particles. Discrimination between nuclear recoils and background electron recoils is afforded by recording both the scintillation and ionisation signals generated within the liquid xenon, with the ratio of these signals being different for the two classes of event. This ratio is calibrated for different incident species using an AmBe neutron source and 60Co γ-ray sources. From our first 31 live days of running ZEPLIN-II, the total exposure following the application of fiducial and stability cuts was 225 kg × days. A background population of radon progeny events was observed in this run, arising from radon emission in the gas purification getters, due to radon daughter ion decays on the surfaces of the walls of the chamber. An acceptance window, defined by the neutron calibration data, of 50% nuclear recoil acceptance between 5 keVee and 20 keVee, had an observed count of 29 events, with a summed expectation of 28.6 ± 4.3 γ-ray and radon progeny induced background events. These figures provide a 90% c.l. upper limit to the number of nuclear recoils of 10.4 events in this acceptance window, which converts to a WIMP–nucleon spin-independent cross-section with a minimum of 6.6 × 10−7 pb following the inclusion of an energy-dependent, calibrated, efficiency. A second run is currently underway in which the radon progeny will be eliminated, thereby removing the background population, with a projected sensitivity of 2 × 10−7 pb for similar exposures as the first run. date: 2007-11 publisher: ELSEVIER SCIENCE BV official_url: https://doi.org/10.1016/j.astropartphys.2007.06.002 vfaculties: VMPS oa_status: green full_text_type: other language: eng primo: open primo_central: open_green verified: verified_manual elements_source: WoS-Lite elements_id: 376787 doi: 10.1016/j.astropartphys.2007.06.002 lyricists_name: Ghag, Chamkaur lyricists_id: CGHAG64 full_text_status: public publication: Astroparticle Physics volume: 28 number: 3 pagerange: 287-302 pages: 16 issn: 0927-6505 citation: Alner, GJ; Araujo, HM; Bewick, A; Bungau, C; Camanzi, B; Carson, MJ; Cashmore, RJ; ... Wolfs, FLH; + view all <#> Alner, GJ; Araujo, HM; Bewick, A; Bungau, C; Camanzi, B; Carson, MJ; Cashmore, RJ; Chagani, H; Chepel, V; Cline, D; Davidge, D; Davies, JC; Daw, E; Dawson, J; Durkin, T; Edwards, B; Gamble, T; Gao, J; Ghag, C; Howard, AS; Jones, WG; Joshi, M; Korolkova, EV; Kudryavtsev, VA; Lawson, T; Lebedenko, VN; Lewin, JD; Lightfoot, P; Lindote, A; Liubarsky, I; Lopes, MI; Luescher, R; Majewski, P; Mavrokoridis, K; McMillan, JE; Morgan, B; Muna, D; Murphy, ASJ; Neves, F; Nicklin, GG; Ooi, W; Paling, SM; da Cunha, JP; Plank, SJS; Preece, RM; Quenby, JJ; Robinson, M; Salinas, G; Sergiampietri, F; Silva, C; Solovov, VN; Smith, NJT; Smith, PF; Spooner, NJC; Sumner, TJ; Thorne, C; Tovey, DR; Tziaferi, E; Walker, RJ; Wang, H; White, JT; Wolfs, FLH; - view fewer <#> (2007) First limits on WIMP nuclear recoil signals in ZEPLIN-II: A two-phase xenon detector for dark matter detection. Astroparticle Physics , 28 (3) pp. 287-302. 10.1016/j.astropartphys.2007.06.002 <https://doi.org/10.1016/j.astropartphys.2007.06.002>. Green open access document_url: https://discovery.ucl.ac.uk/id/eprint/1352150/1/Ghag_0701858v2.pdf