First limits on WIMP nuclear recoil signals in ZEPLIN-II: A two-phase xenon detector for dark matter detection

G. J. Alner; H. M. Araújo; A. Bewick; C. Bungau; B. Camanzi; M. J. Carson; R. J. Cashmore; H. Chagani; V. Chepel; D. Cline; D. Davidge; J. C. Davies; E. Daw; J. Dawson; T. Durkin; B. Edwards; T. Gamble; J. Gao; C. Ghag; A. S. Howard; W. G. Jones; M. Joshi; E. V. Korolkova; V. A. Kudryavtsev; T. Lawson; V. N. Lebedenko; J. D. Lewin; P. Lightfoot; A. Lindote; I. Liubarsky; M. I. Lopes; R. Lüscher; P. Majewski; K. Mavrokoridis; J. E. McMillan; B. Morgan; D. Muna; A. St J Murphy; F. Neves; G. G. Nicklin; W. Ooi; S. M. Paling; J. Pinto da Cunha; S. J S Plank; R. M. Preece; J. J. Quenby; M. Robinson; G. Salinas; F. Sergiampietri; C. Silva; V. N. Solovov; N. J T Smith; P. F. Smith; N. J C Spooner; T. J. Sumner; C. Thorne; D. R. Tovey; E. Tziaferi; R. J. Walker; H. Wang; J. T. White; F. L H Wolfs

doi:10.1016/j.astropartphys.2007.06.002

First limits on WIMP nuclear recoil signals in ZEPLIN-II: A two-phase xenon detector for dark matter detection

G. J. Alner, H. M. Araújo, A. Bewick, C. Bungau, B. Camanzi, M. J. Carson, R. J. Cashmore, H. Chagani, V. Chepel, D. Cline, D. Davidge, J. C. Davies, E. Daw, J. Dawson, T. Durkin, B. Edwards, T. Gamble, J. Gao, C. Ghag, A. S. HowardW. G. Jones, M. Joshi, E. V. Korolkova, V. A. Kudryavtsev, T. Lawson, V. N. Lebedenko, J. D. Lewin, P. Lightfoot, A. Lindote, I. Liubarsky, M. I. Lopes, R. Lüscher, P. Majewski, K. Mavrokoridis, J. E. McMillan, B. Morgan, D. Muna, A. St J Murphy, F. Neves, G. G. Nicklin, W. Ooi, S. M. Paling, J. Pinto da Cunha, S. J S Plank, R. M. Preece, J. J. Quenby, M. Robinson, G. Salinas, F. Sergiampietri, C. Silva, V. N. Solovov, N. J T Smith, P. F. Smith, N. J C Spooner, T. J. Sumner, C. Thorne, D. R. Tovey, E. Tziaferi, R. J. Walker, H. Wang, J. T. White, F. L H Wolfs

Physics and Astronomy (Twin Cities)

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133 Scopus citations

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 keV_ee and 20 keV_ee, 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.

Original language	English (US)
Pages (from-to)	287-302
Number of pages	16
Journal	Astroparticle Physics
Volume	28
Issue number	3
DOIs	https://doi.org/10.1016/j.astropartphys.2007.06.002
State	Published - Nov 2007

Bibliographical note

Funding Information:
This work has been funded by the UK Particle Physics and Astronomy Research Council (PPARC), the US Department of Energy (Grant Nos. DE-FG03-91ER40662 and DE-FG03-95ER40917) and the US National Science Foundation (Grant No. PHY-0139065). We acknowledge support from the Central Laboratories for the Research Councils (CCLRC), the Engineering and Physical Sciences Research Council (EPSRC), the ILIAS integrating activity (Contract R113-CT-2004-506222), the INTAS programme (Grant No. 04-78-6744) and the Research Corporation (Grant No. RA0350). We also acknowledge support from Fundação para a Ciência e a Tecnologia (Project POCI/FP/FNU/63446/2005), the Marie Curie International Reintegration Grant (Grant No. FP6-006651) and a PPARC PIPPS award (Grant PP/D000742/1). We would like to gratefully acknowledge the strong support of Cleveland Potash Ltd., the owners of the Boulby mine, and J. Mulholland and L. Yeoman, the underground facility staff. We would like to thank the team from ITEP, Moscow, led by Dr. D. Akimov for their valuable contribution to the ZEPLIN programme. We acknowledge valuable advice from Professor R. Cousins on the application and extension of the Feldman–Cousins tables.

Keywords

Dark matter
Liquid xenon
Radiation detectors
WIMPs
ZEPLIN-II

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Alner, G. J., Araújo, H. M., Bewick, A., Bungau, C., Camanzi, B., Carson, M. J., Cashmore, R. J., Chagani, H., Chepel, V., Cline, D., Davidge, D., Davies, J. C., Daw, E., Dawson, J., Durkin, T., Edwards, B., Gamble, T., Gao, J., Ghag, C., ... Wolfs, F. L. H. (2007). First limits on WIMP nuclear recoil signals in ZEPLIN-II: A two-phase xenon detector for dark matter detection. Astroparticle Physics, 28(3), 287-302. https://doi.org/10.1016/j.astropartphys.2007.06.002

Alner, GJ, Araújo, 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, Lüscher, R, Majewski, P, Mavrokoridis, K, McMillan, JE, Morgan, B, Muna, D, Murphy, ASJ, Neves, F, Nicklin, GG, Ooi, W, Paling, SM, Pinto da Cunha, J, 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 2007, 'First limits on WIMP nuclear recoil signals in ZEPLIN-II: A two-phase xenon detector for dark matter detection', Astroparticle Physics, vol. 28, no. 3, pp. 287-302. https://doi.org/10.1016/j.astropartphys.2007.06.002

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title = "First limits on WIMP nuclear recoil signals in ZEPLIN-II: A two-phase xenon detector for dark matter detection",

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.",

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author = "Alner, {G. J.} and Ara{\'u}jo, {H. M.} and A. Bewick and C. Bungau and B. Camanzi and Carson, {M. J.} and Cashmore, {R. J.} and H. Chagani and V. Chepel and D. Cline and D. Davidge and Davies, {J. C.} and E. Daw and J. Dawson and T. Durkin and B. Edwards and T. Gamble and J. Gao and C. Ghag and Howard, {A. S.} and Jones, {W. G.} and M. Joshi and Korolkova, {E. V.} and Kudryavtsev, {V. A.} and T. Lawson and Lebedenko, {V. N.} and Lewin, {J. D.} and P. Lightfoot and A. Lindote and I. Liubarsky and Lopes, {M. I.} and R. L{\"u}scher and P. Majewski and K. Mavrokoridis and McMillan, {J. E.} and B. Morgan and D. Muna and Murphy, {A. St J} and F. Neves and Nicklin, {G. G.} and W. Ooi and Paling, {S. M.} and {Pinto da Cunha}, J. and Plank, {S. J S} and Preece, {R. M.} and Quenby, {J. J.} and M. Robinson and G. Salinas and F. Sergiampietri and C. Silva and Solovov, {V. N.} and Smith, {N. J T} and Smith, {P. F.} and Spooner, {N. J C} and Sumner, {T. J.} and C. Thorne and Tovey, {D. R.} and E. Tziaferi and Walker, {R. J.} and H. Wang and White, {J. T.} and Wolfs, {F. L H}",

note = "Funding Information: This work has been funded by the UK Particle Physics and Astronomy Research Council (PPARC), the US Department of Energy (Grant Nos. DE-FG03-91ER40662 and DE-FG03-95ER40917) and the US National Science Foundation (Grant No. PHY-0139065). We acknowledge support from the Central Laboratories for the Research Councils (CCLRC), the Engineering and Physical Sciences Research Council (EPSRC), the ILIAS integrating activity (Contract R113-CT-2004-506222), the INTAS programme (Grant No. 04-78-6744) and the Research Corporation (Grant No. RA0350). We also acknowledge support from Funda{\c c}{\~a}o para a Ci{\^e}ncia e a Tecnologia (Project POCI/FP/FNU/63446/2005), the Marie Curie International Reintegration Grant (Grant No. FP6-006651) and a PPARC PIPPS award (Grant PP/D000742/1). We would like to gratefully acknowledge the strong support of Cleveland Potash Ltd., the owners of the Boulby mine, and J. Mulholland and L. Yeoman, the underground facility staff. We would like to thank the team from ITEP, Moscow, led by Dr. D. Akimov for their valuable contribution to the ZEPLIN programme. We acknowledge valuable advice from Professor R. Cousins on the application and extension of the Feldman–Cousins tables.",

year = "2007",

month = nov,

doi = "10.1016/j.astropartphys.2007.06.002",

language = "English (US)",

volume = "28",

pages = "287--302",

journal = "Astroparticle Physics",

issn = "0927-6505",

publisher = "Elsevier",

number = "3",

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TY - JOUR

T1 - First limits on WIMP nuclear recoil signals in ZEPLIN-II

T2 - A two-phase xenon detector for dark matter detection

AU - Alner, G. J.

AU - Araújo, H. M.

AU - Bewick, A.

AU - Bungau, C.

AU - Camanzi, B.

AU - Carson, M. J.

AU - Cashmore, R. J.

AU - Chagani, H.

AU - Chepel, V.

AU - Cline, D.

AU - Davidge, D.

AU - Davies, J. C.

AU - Daw, E.

AU - Dawson, J.

AU - Durkin, T.

AU - Edwards, B.

AU - Gamble, T.

AU - Gao, J.

AU - Ghag, C.

AU - Howard, A. S.

AU - Jones, W. G.

AU - Joshi, M.

AU - Korolkova, E. V.

AU - Kudryavtsev, V. A.

AU - Lawson, T.

AU - Lebedenko, V. N.

AU - Lewin, J. D.

AU - Lightfoot, P.

AU - Lindote, A.

AU - Liubarsky, I.

AU - Lopes, M. I.

AU - Lüscher, R.

AU - Majewski, P.

AU - Mavrokoridis, K.

AU - McMillan, J. E.

AU - Morgan, B.

AU - Muna, D.

AU - Murphy, A. St J

AU - Neves, F.

AU - Nicklin, G. G.

AU - Ooi, W.

AU - Paling, S. M.

AU - Pinto da Cunha, J.

AU - Plank, S. J S

AU - Preece, R. M.

AU - Quenby, J. J.

AU - Robinson, M.

AU - Salinas, G.

AU - Sergiampietri, F.

AU - Silva, C.

AU - Solovov, V. N.

AU - Smith, N. J T

AU - Smith, P. F.

AU - Spooner, N. J C

AU - Sumner, T. J.

AU - Thorne, C.

AU - Tovey, D. R.

AU - Tziaferi, E.

AU - Walker, R. J.

AU - Wang, H.

AU - White, J. T.

AU - Wolfs, F. L H

N1 - Funding Information: This work has been funded by the UK Particle Physics and Astronomy Research Council (PPARC), the US Department of Energy (Grant Nos. DE-FG03-91ER40662 and DE-FG03-95ER40917) and the US National Science Foundation (Grant No. PHY-0139065). We acknowledge support from the Central Laboratories for the Research Councils (CCLRC), the Engineering and Physical Sciences Research Council (EPSRC), the ILIAS integrating activity (Contract R113-CT-2004-506222), the INTAS programme (Grant No. 04-78-6744) and the Research Corporation (Grant No. RA0350). We also acknowledge support from Fundação para a Ciência e a Tecnologia (Project POCI/FP/FNU/63446/2005), the Marie Curie International Reintegration Grant (Grant No. FP6-006651) and a PPARC PIPPS award (Grant PP/D000742/1). We would like to gratefully acknowledge the strong support of Cleveland Potash Ltd., the owners of the Boulby mine, and J. Mulholland and L. Yeoman, the underground facility staff. We would like to thank the team from ITEP, Moscow, led by Dr. D. Akimov for their valuable contribution to the ZEPLIN programme. We acknowledge valuable advice from Professor R. Cousins on the application and extension of the Feldman–Cousins tables.

PY - 2007/11

Y1 - 2007/11

N2 - 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.

AB - 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.

KW - Dark matter

KW - Liquid xenon

KW - Radiation detectors

KW - WIMPs

KW - ZEPLIN-II

UR - http://www.scopus.com/inward/record.url?scp=35148858889&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=35148858889&partnerID=8YFLogxK

U2 - 10.1016/j.astropartphys.2007.06.002

DO - 10.1016/j.astropartphys.2007.06.002

M3 - Article

AN - SCOPUS:35148858889

SN - 0927-6505

VL - 28

SP - 287

EP - 302

JO - Astroparticle Physics

JF - Astroparticle Physics

IS - 3

ER -

First limits on WIMP nuclear recoil signals in ZEPLIN-II: A two-phase xenon detector for dark matter detection

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