Light Dark Matter Search with a High-Resolution Athermal Phonon Detector Operated above Ground

Open Access

Light Dark Matter Search with a High-Resolution Athermal Phonon Detector Operated above Ground

I. Alkhatib et al. (SuperCDMS Collaboration)

Phys. Rev. Lett. 127, 061801 – Published 4 August 2021

Abstract

We present limits on spin-independent dark matter-nucleon interactions using a 10.6 g Si athermal phonon detector with a baseline energy resolution of $σ_{E} = 3.86 \pm 0.04 (stat)_{- 0.00}^{+ 0.19} (syst) eV$ . This exclusion analysis sets the most stringent dark matter-nucleon scattering cross-section limits achieved by a cryogenic detector for dark matter particle masses from 93 to $140 MeV / c^{2}$ , with a raw exposure of 9.9 g d acquired at an above-ground facility. This work illustrates the scientific potential of detectors with athermal phonon sensors with eV-scale energy resolution for future dark matter searches.

Received 22 July 2020
Revised 6 May 2021
Accepted 8 July 2021

DOI:https://doi.org/10.1103/PhysRevLett.127.061801

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. Funded by SCOAP³.

Published by the American Physical Society

Physics Subject Headings (PhySH)

Dark matter Particle dark matter

Dark matter detectors

Gravitation, Cosmology & AstrophysicsParticles & Fields

Authors & Affiliations

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Article Text

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Issue

Vol. 127, Iss. 6 — 6 August 2021

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Images

Figure 1
A zoomed-in portion of an example event within the analysis ROI. The raw pulse (gray) is compared to the off-line optimal filter result (blue line), the pulse template scaled by the fit result (black dashed line), the FPGA filter result (red line with dots), and the FPGA trigger threshold (black dotted line). The off-line and FPGA optimal filters are highly correlated, but not exactly the same, with corresponding energy estimates for this event of 187 eV and 179 eV, respectively. The offset between the optimal filters and the raw pulse is an artifact of the filters, as they were set up to determine the time of the beginning of the pulse, as opposed to the maximum of the pulse.
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Figure 2
Measured energy spectrum in the DM-search ROI for the full exposure after application of the quality cuts. The data have been normalized to events per gram per day per eV and have been corrected for the event-selection efficiency, but not the trigger efficiency. The inset shows the calibrated $E_{ETF}$ spectrum up to 7 keV, noting the locations of the different spectral peaks. The known values of the dashed lines are 1.5, 5.9, and 6.5 keV for the Al fluorescence (pink), ${}^{55}{Fe}$ $K_{α}$ (blue), and ${}^{55}{Fe}$ $K_{β}$ (cyan) lines, respectively. The two dotted gray lines between 4 and 5 keV in calibrated $E_{ETF}$ are the Si escape peaks [29].
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Figure 3
The 90% C.L. limits on the spin-independent DM-nucleon cross section as a function of DM mass for this work (solid red line), compared to results from other experiments [45, 46, 47, 48, 49, 50, 51]. For above-ground experiments with overburden calculations, the previously ruled out parameter space is shown as the gray shaded region, and the new parameter space ruled out from this search is shown as the red shaded region. For the Collar 2018 surface result, which uses a liquid scintillator cell operated at $1 ° C$ , an overburden calculation would be useful for comparison to the upper edges of the various contours for the surface searches. We note that the systematic error in the baseline energy resolution changes the result within the error of the limit’s line width, thus we only include the result from the 3.86 eV calibration.
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Figure 4
The event spectrum for the DM search data below 40 eV in reconstructed energy. The data have been normalized to events per gram per day per eV and have been corrected for the signal efficiency of the data-quality cuts, but not the confidence ellipse and trigger time cuts. The colored dashed lines represent the calculated event rates for selected DM cross sections and masses from the 90% C.L. OI limit for a single pulse simulation, where the optimum intervals in recoil energy are below 40 eV. Sensitivity to DM masses below $400 MeV / c^{2}$ corresponds to recoil energies below 40 eV, with the lowest masses requiring energy sensitivity down to about 15 eV.
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Physical Review Letters