Phys. Rev. D 107, 122003 (2023) - Results on sub-GeV dark matter from a 10 eV threshold CRESST-III silicon detector

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Results on sub-GeV dark matter from a 10 eV threshold CRESST-III silicon detector

G. Angloher et al. (CRESST Collaboration)

Phys. Rev. D 107, 122003 – Published 23 June 2023

Abstract

We present limits on the spin-independent interaction cross section of dark matter particles with silicon nuclei, derived from data taken with a cryogenic calorimeter with 0.35 g target mass operated in the CRESST-III experiment. A baseline nuclear recoil energy resolution of $(1.36 \pm 0.05) {eV}_{nr}$ , currently the lowest reported for macroscopic particle detectors, and a corresponding energy threshold of $(10.0 \pm 0.2) {eV}_{nr}$ have been achieved, improving the sensitivity to light dark matter particles with masses below $160 MeV / c^{2}$ by a factor of up to 20 compared to previous results. We characterize the observed low energy excess, and we exclude noise triggers and radioactive contaminations on the crystal surfaces as dominant contributions.

Received 9 January 2023
Accepted 5 May 2023

DOI:https://doi.org/10.1103/PhysRevD.107.122003

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

Published by the American Physical Society

Physics Subject Headings (PhySH)

Particle dark matter

Cryogenics Dark matter detectors

Gravitation, Cosmology & AstrophysicsParticles & Fields

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Vol. 107, Iss. 12 — 15 June 2023

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Figure 1
Schematic drawing of the Si CRESST-III detector module. In this work, we use the Si wafer detector as the main target crystal, while the bulk Si crystal is used as a veto detector. The crystals are equipped with TES, held by three Cu sticks, and mounted inside a Cu housing. The ${}^{55}{Fe}$ calibration source encapsulated with concentric layers of glue and gold is attached to the module’s wall. The drawing is not to scale.
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Figure 2
Measured energy spectrum of the Si wafer detector before the coincidence cut with the bulk detector facing the wafer (black) and after the coincidence cut (green). The dashed orange lines indicate the ${}^{55}{Mn}$ $K_{α}$ (5.9 keV) and $K_{β}$ (6.5 keV) lines from the source used for the energy calibration. The dotted pink line shows the Si escape line from the $K_{α}$ x ray at 4.16 keV. No correction with the trigger and cut efficiencies is applied (see text for details).
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Figure 3
The fraction of simulated events that caused a trigger (black) and passed all selection criteria (green). The inset shows an enlargement of the low energy part where the trigger probability is highly energy dependent. The solid orange line shows the error function fit that gives an energy threshold of $(10.0 \pm 0.2) eV$ (dashed black line) and baseline resolution of $(1.36 \pm 0.05) eV$ for the Si wafer detector.
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Figure 4
The energy spectrum (black data points) below 300 eV after applying the selection cuts for the DM analysis taking into account the trigger and cut efficiencies. It exhibits a strong rise in the event rate towards lower energies, the LEE. We fit the LEE with the sum of two power laws [Eq. (1), orange line]. The dashed green line shows the distribution of the baseline triggers derived from analyzing the randomly collected frames (see text for details). The solid green line shows the distribution of the noise triggers. A gap between this distribution and the data rules out noise triggers as the source of the LEE. The yellow histogram shows the distribution obtained from applying the optimum filter to the inverted data stream perfectly agreeing with the noise trigger distribution. Additionally, the differential energy spectra for two DM masses, $0.3 GeV / c^{2}$ (pink) and $0.5 GeV / c^{2}$ (blue), expected for interaction cross sections excluded with 90% CL in this work (red limit line in Fig. 5) are shown.
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Figure 5
Upper limit on the elastic spin-independent DM-nucleon scattering cross section at 90% confidence level. The thick solid red line shows the result of this work obtained with a Si detector [44]. The previous CRESST-III result from a ${CaWO}_{4}$ crystal operated underground [7] is depicted with the darker red solid line. Constraints obtained by the solid-state cryogenic detectors operated above ground are shown by dashed lines: dark red for CRESST-surf with an ${Al}_{2} O_{3}$ target [48], green for SuperCDMS-CPD [16], and blue for SuperCDMS-0VeV [18], the latter two operating a Si target. Results of hydrogenated organic scintillators by J. I. Collar [49] are shown as the dash-dotted gray line.
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Physical Review D

covering particles, fields, gravitation, and cosmology

Results on sub-GeV dark matter from a 10 eV threshold CRESST-III silicon detector

G. Angloher et al. (CRESST Collaboration)

Phys. Rev. D 107, 122003 – Published 23 June 2023

Abstract

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Article Text

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Issue

Physical Review D

covering particles, fields, gravitation, and cosmology

Results on sub-GeV dark matter from a 10 eV threshold CRESST-III silicon detector

G. Angloher et al. (CRESST Collaboration)

Phys. Rev. D 107, 122003 – Published 23 June 2023

Abstract

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