Results from the first stage of a UK Galactic dark matter search using low background sodium iodide detectors

Quenby, J. J.; Sumner, T. J.; Li, J.P.; Bewick, A.; Grant, Sarah; Shaul, D.; Smith, N. J. T.; Jones, W. G.; Davies, G.; Zammit, Charles; Caplin, A.D.; Stradling, R. A.; Ali, Tariq; Lally, C.H.; Smith, P.F.; Homer, G.J.; Arnison, G.; Lewin, J.D.; Alner, G. J.; Cruise, A. M.; Putte, M.J.J. van den; Spooner, N. J. C.; Barton, J. C.; Blake, P. R.; Lea, M. J.; Stefányi, P.; Saunders, J.

doi:10.1016/0370-2693(95)00355-o

Cited by 26 publications

(6 citation statements)

References 20 publications

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“…This has been studied in some detail by various authors [11, 55]. Figure 9 shows measured comparative differential pulse shapes from the UKDMC NaI group [106, 118]. Figure 10 compares γ -ray and neutron induced nuclear recoil calibration time constant distributions (using simple single exponential fits to each pulse) with the background obtained from their working experiment.…”

Section: Neutralino Detection Principles and Techniquesmentioning

confidence: 99%

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Experimental Searches for Dark Matter

Sumner

2002

Living Rev. Relativ.

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There is now an enormously rich variety of experimental techniques being brought to bear on experimental searches for dark matter, covering a wide range of suggested forms for it. The existence of “dark matter”, in some form or other, is inferred from a number of relatively simple observations and the problem has been known for over half a century. To explain “dark matter” is one of the foremost challenges today — the answer will be of fundamental importance to cosmologists, astrophysicists, particle physicists, and general relativists. In this article, I will give a brief review of the observational evidence (concentrating on areas of current significant activity), followed by anequally brief summary of candidate solutions for the ‘dark matter’. I will then discuss experimental searches, both direct and indirect. Finally, I will offer prospects for the future.

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Section: Neutralino Detection Principles and Techniquesmentioning

confidence: 99%

“… Differential time constant distributions from the UK NaI experiment [ 106, 118 ] showing the measured background (solid line + data points), and neutron and γ-ray calibration distributions. …”

Section: Neutralino Detection Principles and Techniquesmentioning

confidence: 99%

Experimental Searches for Dark Matter

Sumner

2002

Living Rev. Relativ.

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“…Inorganic crystal scintillators are popular choices as target materials for direct dark matter search experiments. The high light yield and pulse shape differences between nuclear and electron recoils explain why thallium activated sodium iodide (NaI(Tl)) crystals are the oldest scintillators used in such experiments [6]. They still remain one of the best detectors at determining spindependent WIMP-nucleon limits, and the ANAIS [7], DAMA/NaI [8] and ELEGANT-V [9] direct search experiments utilise them.…”

Section: Introductionmentioning

confidence: 99%

Measurement of the quenching factor of Na recoils in NaI(Tl)

Chagani¹,

Majewski²,

Daw³

et al. 2008

J. Inst.

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Measurements of the quenching factor for sodium recoils in a 5 cm diameter NaI(Tl) crystal at room temperature have been made at a dedicated neutron facility at the University of Sheffield. The crystal has been exposed to 2.45 MeV mono-energetic neutrons generated by a Sodern GENIE 16 neutron generator, yielding nuclear recoils of energies between 10 and 100 keVnr. A cylindrical BC501A detector has been used to tag neutrons that scatter off sodium nuclei in the crystal. Cuts on pulse shape and time of flight have been performed on pulses recorded by an Acqiris DC265 digitiser with a 2 ns sampling time. Measured quenching factors of Na nuclei range from 19% to 26% in good agreement with other experiments, and a value of 25.2 ± 6.4% has been determined for 10 keV sodium recoils. From pulse shape analysis, the mean times of pulses from electron and nuclear recoils have been compared down to 2 keVee. The experimental results are compared to those predicted by Lindhard theory, simulated by the SRIM Monte Carlo code, and a preliminary curve calculated by Prof. Akira Hitachi.

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“…These are seen at ∼1000/day above an 18 hit threshold comprising relatively prompt flashes of light attributed to discharges from the dynodes [3]. In dark matter detectors based on NaI, liquid Xe and other scintillators where high sensitivity and low background is needed, a likely related class of events sometimes termed "step" events is seen [4,5]. The drive for lower thresholds and lower backgrounds means that such unusual and rare events will become an increasingly significant source of systematic error in these and other planned PMT-based low background detectors.…”

Section: Introductionmentioning

confidence: 99%

Reduction of coincident photomultiplier noise relevant to astroparticle physics experiments

Robinson¹,

Lightfoot²,

Carson³

et al. 2005

Nuclear Instruments and Methods in Physics Research Section A:

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In low background and low threshold particle astrophysics experiments using observation of Cherenkov or scintillation light it is common to use pairs or arrays of photomultipliers operated in coincidence. In such circumstances, for instance in dark matter and neutrino experiments, unexpected PMT noise events have been observed, probably arising from generation of light from one PMT being detected by one or more other PMTs. We describe here experimental investigation of such coincident noise events and development of new techniques to remove them using novel pulse shape discrimination procedures. When applied to data from a low background NaI detector with facing PMTs the new procedures are found to improve noise rejection by a factor of 20 over conventional techniques, with significantly reduced loss of signal events.

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Results from the first stage of a UK Galactic dark matter search using low background sodium iodide detectors

Cited by 26 publications

References 20 publications

Experimental Searches for Dark Matter

Experimental Searches for Dark Matter

Measurement of the quenching factor of Na recoils in NaI(Tl)

Reduction of coincident photomultiplier noise relevant to astroparticle physics experiments

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