Identification of the low-energy excess in dark matter searches with crystal defects

Heikinheimo, Matti; Sassi, Sebastian; Nordlund, K.; Tuominen, Kimmo; Mirabolfathi, N.

doi:10.1103/physrevd.106.083009

Cited by 5 publications

(7 citation statements)

References 33 publications

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“…Here, we are assuming that the origin of the low-energy excess observed in the low-threshold direct detection experiments is attributed to a controllable background. In a separate study, the authors have elaborated on using phonon-mediated detectors to understand the origin of these events [105]. Figure 7 represents the annual modulation of a dark matter particle with a mass of 300 MeV/c 2 and a cross-section of 10 −39 cm 2 scattering on silicon target over the year 2020.…”

Section: Resultsmentioning

confidence: 99%

“…Semiconductor targets, such as silicon or germanium, can be utilized as cryogenic solidstate ionization detectors, where sensitivity to single electron ionization events has been demonstrated [67][68][69], corresponding to nuclear recoil energy detection threshold of  10 ( ) eV. The ionization threshold is the minimum energy to create a single electron-hole pair excitation via nuclear recoil interaction.…”

Section: Introductionmentioning

confidence: 99%

“…Similar methods were used to describe the effect of these defects on phonon-based recoil energy measurements [76]. Another related work [77] discussed the possibility of utilizing this effect in understanding the origin of the low energy excess [78] observed in several low threshold detectors.…”

Section: Introductionmentioning

confidence: 99%

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Daily and annual modulation rate of low mass dark matter in silicon detectors

Dinmohammadi,

Heikinheimo,

Mirabolfathi

et al. 2024

J. Phys. G: Nucl. Part. Phys.

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Low-threshold solid-state detectors with single electron excitation sensitivity can probe nuclear recoil energies in the sub-100 eV range, coinciding with the typical threshold displacement energies in the detector material. We investigate the daily and annual modulation of the observable event rate for dark matter mass ranging from 0.2 to 5 GeV/c^2 in a silicon detector, considering the energy threshold and the direction of the nuclear recoil. The data for the energy threshold is obtained from a molecular dynamics simulation. It is shown that the directional dependence of the threshold energy and the motion of the laboratory result in the modulation of the interaction event rate. We demonstrate silicon’s average annual interaction rate is more considerable than germanium for low-mass dark matter. However, their event rates take a similar trend in large dark matter masses. Thus, silicon can be a reliable target to discriminate low-mass dark matter from backgrounds. We also find 8-hour and 12-hour periodicities in the time series of event rates for silicon detectors due to the 45-degree symmetry in the silicon crystal structure.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Daily and annual modulation rate of low mass dark matter in silicon detectors

Dinmohammadi,

Heikinheimo,

Mirabolfathi

et al. 2024

J. Phys. G: Nucl. Part. Phys.

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“…To quantify how the energy loss effect in diamond can be used to identify the nuclear recoil origin of the spectrum, we have performed a likelihood ratio test for simulated data sets, using the three best fit functions given in table 1 as the physical recoil rate. We obtain the required number of events in a diamond detector in the event selection window eV, using 1 eV bins, for a 3σ observation of the peak/dip feature, as described in more detail in [20]. We find that unless the peak is masked by the exponential noise component, the feature can be observed with just 440 to 710 events in the selection window, depending slightly on the power law index β of the fit parameters.…”

Section: Identifying Nuclear Recoilsmentioning

confidence: 99%

Energy loss due to defect creation in solid state detectors

Heikinheimo

Sassi

Tuominen

et al. 2023

SciPost Phys. Proc.

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The threshold displacement energy in solid state detector materials varies from several eV to \lesssim≲ 100 eV. If a stable or long lived defect is created as a result of a nuclear recoil event, some part of the recoil energy is stored in the deformed lattice and is therefore not observable in a phonon detector. Thus, an accurate model of this effect is necessary for precise calibration of the recoil energy measurement in low threshold phonon detectors. Furthermore, the sharpness of the defect creation threshold varies between materials. For a hard material such as diamond, the sharp threshold will cause a sudden onset of the energy loss effect, resulting in a prominent peak in the observed recoil spectrum just below the threshold displacement energy. We describe how this effect can be used to discriminate between nuclear and electron recoils using just the measured recoil spectrum.

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“…Most of the anticipated background sources, such as photons or electrons, would give Figure 1: Energy loss, averaged over recoil direction, as a function of the recoil energy in silicon, germanium, sapphire and diamond. The figure has appeared before in [20].…”

Section: Introductionmentioning

confidence: 98%

Energy loss due to defect creation in solid state detectors

Heikinheimo¹,

Sassi²,

Tuominen³

et al. 2022

Preprint

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The threshold displacement energy in solid state detector materials varies from several eV to 100 eV. If a stable or long lived defect is created as a result of a nuclear recoil event, some part of the recoil energy is stored in the deformed lattice and is therefore not observable in a phonon detector. Thus, an accurate model of this effect is necessary for precise calibration of the recoil energy measurement in low threshold phonon detectors. Furthermore, the sharpness of the defect creation threshold varies between materials. For a hard material such as diamond, the sharp threshold will cause a sudden onset of the energy loss effect, resulting in a prominent peak in the observed recoil spectrum just below the threshold displacement energy. We describe how this effect can be used to discriminate between nuclear and electron recoils using just the measured recoil spectrum.

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Identification of the low-energy excess in dark matter searches with crystal defects

Cited by 5 publications

References 33 publications

Daily and annual modulation rate of low mass dark matter in silicon detectors

Daily and annual modulation rate of low mass dark matter in silicon detectors

Energy loss due to defect creation in solid state detectors

Energy loss due to defect creation in solid state detectors

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