The expected background spectrum in NaI dark matter detectors and the DAMA result

Kudryavtsev, V. A.; Robinson, M.; Spooner, N. J. C.

doi:10.1016/j.astropartphys.2009.12.003

Cited by 30 publications

(21 citation statements)

References 15 publications

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“…Moreover, it was recently pointed out in ref. [40] that the radioactive background rates in the DAMA experiment are likely larger than what was estimated by DAMA. If true, that would imply a smaller unmodulated amplitude of the putative signal and hence a larger modulation fraction.…”

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confidence: 90%

Statistical tests of noise and harmony in dark matter modulation signals

2012

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The aim of the current work is a detailed time-series analysis of the data from Dark Matter direct detection experiments as well as related datasets. We examine recent claims that the cosmic ray muon flux can be responsible for generating the modulation signals seen by DAMA and, more recently, by the CoGeNT collaboration. We find no evidence for such a strong correlation and show that the two phenomena differ in their power spectrum, phase, and possibly in amplitude. In addition, we investigate in more detail, the time dependence of Dark Matter scattering. Since the signal is periodic with period of a year (due to the Earth's motion around the Sun), the presence of higher harmonics can be expected. We show that the higher harmonics generically have similar phase to the annual modulation and the biannual mode in particular could provide another handle in searching for Dark Matter in the laboratory.

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confidence: 90%

Statistical tests of noise and harmony in dark matter modulation signals

2012

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“…When simulating intrinsic background we used the same approach as in Ref. [22]. Only events with energy deposition in one crystal exceeding 10 keV were counted.…”

Section: Simulations For a Tonne-scale Targetmentioning

confidence: 99%

Radioactive background in a cryogenic dark matter experiment

Tomasello¹,

Robinson²,

Kudryavtsev³

2010

Astroparticle Physics

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a b s t r a c tNew generation dark matter experiments aim at exploring the 10 À9 À 10 À10 pb cross-section region for WIMP-nucleon scalar interactions. Neutrons and gamma-rays, due to radioactive processes, are produced in the detector components and are one of the main factors that can limit detector sensitivity. Estimation of the background from this source then becomes a crucial task for designing future large-scale detectors. Radioactive background event rates from some detector components (such as copper and stainless steel), as well as from rock and concrete (lab walls), were estimated in this work for a hypothetical cryogenic dark matter detector (for instance EURECA) with a target mass of 100-1000 kg. Different shielding configurations (water, lead, polyethylene, plexiglass) were considered. Neutrons and photons were propagated to the detector using GEANT4. Some requirements for the radio-purity of the materials were deduced from the results of these simulations. Thickness of shielding in different configurations and the required gamma discrimination factor were investigated.

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“…A number of hypotheses for the origin of DAMA's annually modulating signal have been proposed, ranging from alternative dark matter models [27] to potential sources of background [28][29][30][31]. No background has yet been shown to completely account for the DAMA modulation signal [32][33][34][35][36][37]. Atmospheric muons are one such background, the production of which in the Earth's atmosphere is correlated with the air density in the upper atmosphere and therefore exhibits a seasonal modulation [38][39][40][41][42][43].…”

Section: Introductionmentioning

confidence: 99%

Measurement of muon annual modulation and muon-induced phosphorescence in NaI(Tl) crystals with DM-Ice17

et al. 2016

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We report the measurement of muons and muon-induced phosphorescence in DM-Ice17, a NaI(Tl) direct detection dark matter experiment at the South Pole. Muon interactions in the crystal are identified by their observed pulse shape and large energy depositions. The measured muon rate in DM-Ice17 is 2.93 ± 0.04 µ/crystal/day with a modulation amplitude of 12.3 ± 1.7%, consistent with expectation. Following muon interactions, we observe long-lived phosphorescence in the NaI(Tl) crystals with a decay time of 5.5 ± 0.5 s. The prompt energy deposited by a muon is correlated to the amount of delayed phosphorescence, the brightest of which consist of tens of millions of photons. These photons are distributed over tens of seconds with a rate and arrival timing that do not mimic a scintillation signal above 2 keVee. While the properties of phosphorescence vary among individual crystals, the annually-modulating signal observed by DAMA cannot be accounted for by phosphorescence with the characteristics observed in DM-Ice17.PACS numbers: 95.35.+d, 29.40.Mc, 95.85.Ry

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The expected background spectrum in NaI dark matter detectors and the DAMA result

Cited by 30 publications

References 15 publications

Statistical tests of noise and harmony in dark matter modulation signals

Statistical tests of noise and harmony in dark matter modulation signals

Radioactive background in a cryogenic dark matter experiment

Measurement of muon annual modulation and muon-induced phosphorescence in NaI(Tl) crystals with DM-Ice17

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