Quenching factor measurements of sodium nuclear recoils in NaI:Tl determined by spectrum fitting

Bignell, L. J.; Mahmood, I.; Nuti, F.; Lane, G. J.; Akber, A.; Barberio, E.; Baroncelli, To.; Coombes, B. J.; Dix, W.; Dowie, J. T. H.; Gerathy, M. S. M.; Gray, Tom J.; McCormick, B. P.; Mitchell, A. J.; Rahman, Md. Shahinur; Scutti, F.; Spinks, N. J.; Stuchbery, A. E.; Timmers, H.; Urquijo, P.; Wang, L.; Zhong, Yi-Ming; Zurowski, Madeleine J.

doi:10.1088/1748-0221/16/07/p07034

Cited by 19 publications

(12 citation statements)

References 19 publications

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“…The total charge of the waveform is taken as the sum of these two components. For further details, including a schematic representation of this approach, see Ref [15].…”

Section: Data Processing and Event Selectionmentioning

confidence: 99%

Pulse Shape Discrimination of low-energy nuclear and electron recoils for improved particle identification in NaI:Tl

Spinks¹,

Bignell²,

Lane³

et al. 2022

Preprint

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The scintillation mechanism in NaI:Tl crystals produces different pulse shapes that are dependent on the incoming particle type. The time distribution of scintillation light from nuclear recoil events decays faster than for electron recoil events and this difference can be categorised using various Pulse Shape Discrimination (PSD) techniques. In this study, we measured nuclear and electron recoils in a NaI:Tl crystal, with electron equivalent energies between 2 and 40 keV. We report on a new PSD approach, based on an event-type likelihood; this outperforms the charge-weighted mean-time, which is the conventional metric for PSD in NaI:Tl. Furthermore, we show that a linear combination of the two methods improves the discrimination power at these energies.

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“…The total charge of the waveform is taken as the sum of these two components. For further details, including a schematic representation of this approach, see Ref [15].…”

Section: Data Processing and Event Selectionmentioning

confidence: 99%

Pulse Shape Discrimination of low-energy nuclear and electron recoils for improved particle identification in NaI:Tl

Spinks¹,

Bignell²,

Lane³

et al. 2022

Preprint

Self Cite

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“…Independent experiments with the same target material NaI(Tl) as DAMA would go a long way to resolve the controversy, allowing a model-independent test of the annual modulation signal. However, the lack of a deep understanding and/or modelling of quenching factors for scintillation of nuclear recoils in NaI(Tl) introduces some systematics in this test for DM candidates releasing the energy through nuclear recoils [239][240][241][242][243][244]. Better measurements of quenching factors for crystals having different properties using the same analysis methods and set-ups would help [245].…”

Section: Puzzling Excesses In Dark Matter Searches and How To Resolve...mentioning

confidence: 99%

Snowmass2021 Cosmic Frontier White Paper: Puzzling Excesses in Dark Matter Searches and How to Resolve Them

Leane¹,

Shin²,

Yang³

et al. 2022

Preprint

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Intriguing signals with excesses over expected backgrounds have been observed in many astrophysical and terrestrial settings, which could potentially have a dark matter origin. Astrophysical excesses include the Galactic Center GeV gamma-ray excess detected by the Fermi Gamma-Ray Space Telescope, the AMS antiproton and positron excesses, and the 511 and 3.5 keV X-ray lines. Direct detection excesses include the DAMA/LIBRA annual modulation signal, the XENON1T excess, and low-threshold excesses in solid state detectors. We discuss avenues to resolve these excesses, with actions the field can take over the next several years.

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“…This is not the case for NaI(Tl) scintillators. Measurements of QF in the energy region relevant for DM searches, and in particular for the comparison with DAMA/LIBRA in case the signal is attributed to nuclear recoils, do not agree, and in fact are affected by strong discrepancies (QF dependent on the energy versus constant values, for instance) [59][60][61][62][63][64][65][66][67][68][69].…”

Section: The Neutron Calibration Programmentioning

confidence: 99%

Improving ANAIS-112 sensitivity to DAMA/LIBRA signal with machine learning techniques

Coarasa,

Apilluelo,

Amaré

et al. 2022

Preprint

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The DAMA/LIBRA observation of an annual modulation in the detection rate compatible with that expected for dark matter particles from the galactic halo has accumulated evidence for more than twenty years. It is the only hint of a direct detection of the elusive dark matter, but it is in strong tension with the negative results of other very sensitive experiments, requiring ad-hoc scenarios to reconcile all the present experimental results. Testing the DAMA/LIBRA result using the same target material, NaI(Tl), removes the dependence on the particle and halo models and is the goal of the ANAIS-112 experiment, taking data at the Canfranc Underground Laboratory in Spain since August 2017 with 112.5 kg of NaI(Tl). At very low energies, the detection rate is dominated by non-bulk scintillation events and careful event selection is mandatory. This article summarizes the efforts devoted to better characterize and filter this contribution in ANAIS-112 data using a boosted decision tree (BDT), trained for this goal with high efficiency. We report on the selection of the training populations, the procedure to determine the optimal cut on the BDT parameter, the estimate of the efficiencies for the selection of bulk scintillation in the region of interest (ROI), and the evaluation of the performance of this analysis with respect to the previous filtering. The improvement achieved in background rejection in the ROI, but moreover, the increase in detection efficiency, push the ANAIS-112 sensitivity to test the DAMA/LIBRA annual modulation result beyond 3σ with three-year exposure, being possible to reach 5σ by extending the data taking for a few more years than the scheduled 5 years which were due in August 2022.

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Quenching factor measurements of sodium nuclear recoils in NaI:Tl determined by spectrum fitting

Cited by 19 publications

References 19 publications

Pulse Shape Discrimination of low-energy nuclear and electron recoils for improved particle identification in NaI:Tl

Pulse Shape Discrimination of low-energy nuclear and electron recoils for improved particle identification in NaI:Tl

Snowmass2021 Cosmic Frontier White Paper: Puzzling Excesses in Dark Matter Searches and How to Resolve Them

Improving ANAIS-112 sensitivity to DAMA/LIBRA signal with machine learning techniques

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