Publications
246 results found
Sumneri TJ, Araujo HM, Bewick A, et al., 2007, The zeplin III detector: Results from surface calibrations, Pages: 288-295
ZEPLIN-I11 is a direct dark-matter search instrument using liquid xenon as a target. Both scintillation light and ionisation charge are measured. The instrument has been built and tested in a surface laboratory, and we present some of the results here, including design thermal control system verification, photomultiplier calibration and two-phase operation showing simultaneous measurement of scintillation and charge and position reconstruction.
Sumner TJ, Akimov DY, Alner GJ, et al., 2007, The ZEPLIN III detector;: Results from surface calibrations, 7th UCLA Symposium on Sources and Detection of Dark Matter and Dark Energy in the Universe, Publisher: ELSEVIER, Pages: 108-112, ISSN: 0920-5632
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- Citations: 1
Alner GJ, Araujo HM, Bewick A, et al., 2007, Limits on spin-dependent WIMP-nucleon cross-sections from the first ZEPLIN-II data, PHYSICS LETTERS B, Vol: 653, Pages: 161-166, ISSN: 0370-2693
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- Citations: 32
Alner GJ, Araujo HM, Bewick A, et al., 2007, First limits on WIMP nuclear recoil signals in ZEPLIN-II: A two-phase xenon detector for dark matter detection, Astroparticle Physics, Vol: 28, Pages: 287-302, ISSN: 1873-2852
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.
Lindote A, Araujo HM, da Cunha JP, et al., 2007, Preliminary results on position reconstruction for ZEPLIN III, 7th International Conference on Position-Sensitive Detectors, Publisher: ELSEVIER, Pages: 200-203, ISSN: 0168-9002
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- Citations: 5
Akimov DY, Alner GJ, Araujo HM, et al., 2007, The ZEPLIN-III dark matter detector: Instrument design, manufacture and commissioning, Astroparticle Physics, Vol: 27, Pages: 46-60, ISSN: 1873-2852
We present details of the technical design, manufacture and testing of the ZEPLIN-III dark matter experiment. ZEPLIN-III is a twophasexenon detector which measures both the scintillation light and the ionisation charge generated in the liquid by interacting particlesand radiation. The instrument design is driven by both the physics requirements and by the technology requirements surrounding the useof liquid xenon. These include considerations of key performance parameters, such as the efficiency of scintillation light collection, restrictionsplaced on the use of materials to control the inherent radioactivity levels, attainment of high vacuum levels and chemical contaminationcontrol. The successful solution has involved a number of novel design and manufacturing features which will be of specific use tofuture generations of direct dark matter search experiments as they struggle with similar and progressively more demanding requirements.
Shaul D N, et al, 2006, Solar And Cosmic Ray Physics And The Space Environment: Studies For And With LISA, LASER INTERFEROMETER SPACE ANTENNA: 6th International LISA Symposium, Publisher: AIP Press, Pages: 172-178, ISSN: 0094-243X
Araujo HM, Akimov DY, Alner GJ, et al., 2006, The ZEPLIN-III dark matter detector: Performance study using an end-to-end simulation tool, Astroparticle Physics, Vol: 26, Pages: 140-153, ISSN: 1873-2852
We present results from a GEANT4-based Monte Carlo tool for end-to-end simulations of the ZEPLIN-III dark matter experiment.ZEPLIN-III is a two-phase detector which measures both the scintillation light and the ionisation charge generated in liquid xenon byinteracting particles and radiation. The software models the instrument response to radioactive backgrounds and calibration sources,including the generation, ray-tracing and detection of the primary and secondary scintillations in liquid and gaseous xenon, and subsequentprocessing by data acquisition electronics. A flexible user interface allows easy modification of detector parameters at run time.Realistic datasets can be produced to help with data analysis, an example of which is the position reconstruction algorithm developedfrom simulated data. We present a range of simulation results confirming the original design sensitivity of a few times 108 pb to theWIMP-nucleon cross-section.
Meli A, Quenby JJ, 2006, Scattering models at super-luminal shocks - a numerical study, 13th International Symposium on Very High Energy Cosmic Ray Interactions, Publisher: ELSEVIER SCIENCE BV, Pages: 505-508, ISSN: 0920-5632
Alner GJ, Araujo H, Bewick A, et al., 2005, The DRIFT-II dark matter detector:: Design and commissioning, NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, Vol: 555, Pages: 173-183, ISSN: 0168-9002
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- Citations: 69
Dawson JV, Howard AS, Akimov D, et al., 2005, A study of the scintillation induced by alpha particles and gamma rays in liquid xenon in an electric field, Nuclear Instruments & Methods in Physics Research Section A - Accelerators Spectrometers Detectors and Associated Equipment, Vol: 545, Pages: 690-698, ISSN: 0168-9002
Scintillation produced in liquid xenon by alpha particles and gamma rays has been studied as a function of applied electric field. For back scattered gamma rays with energy of about 200 keV, the number of scintillation photons was found to decrease by 64±2% with increasing field strength. Consequently, the pulse shape discrimination power between alpha particles and gamma rays is found to reduce with increasing field, but remaining non-zero at higher fields.
Alner GJ, Araujo HM, Arnison GJ, et al., 2005, Limits on WIMP cross-sections from the NAIAD experiment at the boulby underground laboratory, PHYS LETT B, Vol: 616, Pages: 17-24, ISSN: 0370-2693
The NAIAD experiment (NaI Advanced Detector) for WIMP dark matter searches at the Boulby Underground Laboratory (North Yorkshire, UK) ran from 2000 until 2003. A total of 44.9 kg x years of data collected with 2 encapsulated and 4 unencapsulated NaI(Tl) crystals with high light yield were included in the analysis. We present final results of this analysis carried out using pulse shape discrimination. No signal associated with nuclear recoils from WIMP interactions was observed in any run with any crystal. This allowed us to set upper limits on the WIMP-nucleon spin-independent and WIMP-proton spin-dependent cross-sections. The NAIAD experiment has so far imposed the most stringent constraints on the spin-dependent WIMP-proton cross-section. (c) 2005 Elsevier B.V. All rights reserved.
Alner GJ, Araujo H, Arnison GJ, et al., 2005, First limits on nuclear recoil events from the ZEPLIN I galactic dark matter detector, ASTROPARTICLE PHYSICS, Vol: 23, Pages: 444-462, ISSN: 0927-6505
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- Citations: 100
Alner GJ, Araujo H, Arnison GJ, et al., 2005, Nuclear recoil limits from the ZEPLIN I liquid xenon WIMP dark matter detector, 6th UCLA Symposium on Sources and Detection of Dark Matter and Dark Energy in the Universe, Publisher: ELSEVIER SCI LTD, Pages: 245-249, ISSN: 1387-6473
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- Citations: 2
Alner GJ, Atac M, Bewick A, et al., 2005, Status of the ZEPLIN II experiment, 6th UCLA Symposium on Sources and Detection of Dark Matter and Dark Energy in the Universe, Publisher: ELSEVIER SCI LTD, Pages: 259-263, ISSN: 1387-6473
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- Citations: 12
Meli A, Quenby JJ, Becker JK, 2005, On the cosmic rays acceleration at super-luminal shocks, 29th International Cosmic Ray Conference, Publisher: TATA INST FUNDAMENTAL RESEARCH, Pages: 229-232
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- Citations: 1
Alner GJ, Araujo HM, Arnison GJ, et al., 2005, Zeplin I: first limits on nuclear recoil rate, Singapore, 5th international workshop on the identification of dark matter, 6 - 10 September 2004, Edinburgh, SCOTLAND, Publisher: World Scientific Publ Co Pte Ltd, Pages: 218-223
Meli A, Quenby JJ, 2005, Particle acceleration and scattering models at super-luminal shocks, Conference on Astrophysical Sources of High Energy Particles and Radiation, Publisher: AMER INST PHYSICS, Pages: 382-384, ISSN: 0094-243X
Gallagher DL, Horwitz J, Perez J, et al., 2005, Particle acceleration in astrophysical plasmas: geospace and beyond, Publisher: AGU, ISBN: 9780875904214
Quenby JJ, Meli A, 2005, Studies of relativistic shock acceleration, especially relevant to GRB, Particle acceleration in astrophysical plasmas: geospace and beyond, Editors: Gallagher, Horwitz, Perez, Preece, Quenby, Publisher: AGU, ISBN: 9780875904214
Quenby JJ, 2005, Baryonic dark matter - an outsider's view, Singapore, 5th international workshop on the identification of dark matter, Edinburgh, Scotland, 6 - 10 September 2004, Publisher: World Scientific, Pages: 151-158
Davies JC, Quenby JJ, 2005, Deep, dark and directional: the DRIFT dark matter detector at Boulby mine, Fundamental interactions: Lake Louise Winter Institute, Lake Louise, Alberta, 20 - 26 February 2005
Quenby JJ, Meli A, 2005, Diffusive shock acceleration in astrophysics, Particle acceleration in astrophysical plasmas: geospace and beyond, Editors: Gallagher, Horwitz, Perez, Preece, Quenby, Publisher: AGU, ISBN: 9780875904214
Alner GJ, Araujo HM, Arnison GJ, et al., 2005, Limits on wimp cross-sections from the NAIAD experiment at Boulby, Singapore, 5th international workshop on the identification of dark matter, 6 - 10 September 2004, Edinburgh, SCOTLAND, Publisher: World Scientific Publ Co Pte Ltd, Pages: 224-229
Alner GJ, Araujo H, Ayad R, et al., 2004, The DRIFT-I dark matter detector at Boulby: Design, installation and operation, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol: 535, Pages: 644-655, ISSN: 0168-9002
DRIFT-I, the first full-scale gaseous dark matter detector, has recently been installed at ∼1100 m depth at the Boulby Underground Laboratory, UK. The DRIFT concept offers high background discrimination and sensitivity to the direction of WIMP-induced nuclear recoils, the latter being of particular importance in the search for evidence of WIMPs in our galaxy, In this paper we discuss the design of the DRIFT-I detector and its installation and operation at Boulby. We also present results of early engineering runs and outline plans for the future. © 2004 Elsevier B.V. All rights reserved.
Alner GJ, Araujo H, Ayad R, et al., 2004, The DRIFT-I dark matter detector at Boulby:: design, installation and operation, NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, Vol: 535, Pages: 644-655, ISSN: 0168-9002
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- Citations: 35
Araújo HM, Bewick A, Davidge D, et al., 2004, Low-temperature study of 35 photomultiplier tubes for the ZEPLIN III experiment, NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, Vol: 521, Pages: 407-415, ISSN: 0168-9002
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- Citations: 21
Ahmed B, Alner GJ, Araujo H, et al., 2003, The NAIAD experiment for WIMP searches at Boulby mine and recent results, Astroparticle Physics, Vol: 19, Pages: 691-702, ISSN: 1873-2852
The NAIAD experiment (NaI Advanced Detector) for weakly interacting massive particle (WIMP) dark mattersearches at Boulby mine (UK) is described. The detector consists of an array of encapsulated and unencapsulatedNaI(Tl) crystals with high light yield. Six crystals are collecting data at present. Data accumulated by four of them (10.6kg year exposure) have been used to set upper limits on the WIMP–nucleon spin-independent and WIMP–protonspin-dependent cross-sections. Pulse shape analysis has been applied to discriminate between nuclear recoils, as may becaused by WIMP interactions, and electron recoils due to gamma background. Various calibrations of crystals arepresented.
Meli A, Quenby JJ, 2003, Particle acceleration in ultra-relativistic parallel shock waves, ASTROPARTICLE PHYSICS, Vol: 19, Pages: 637-648, ISSN: 0927-6505
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- Citations: 19
Meli A, Quenby JJ, 2003, Particle acceleration in ultra-relativistic oblique shock waves, ASTROPARTICLE PHYSICS, Vol: 19, Pages: 649-666, ISSN: 0927-6505
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- Citations: 36
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