Nuclear Recoil Identification in a Scientific Charge-Coupled Device

Abstract

Charge-coupled devices (CCDs) are a leading technology in direct dark matter searches because of their eV-scale energy threshold and high spatial resolution. The sensitivity of future CCD experiments could be enhanced by distinguishing nuclear recoil signals from electronic recoil backgrounds in the CCD silicon target. We present a technique for event-by-event identification of nuclear recoils based on the spatial correlation between the primary ionization event and the lattice defect left behind by the recoiling atom, later identified as a localized excess of leakage current under thermal stimulation. By irradiating a CCD with an ${}^{241}$Am${}^9$Be neutron source, we demonstrate $>93\%$ identification efficiency for nuclear recoils with energies $>150$ keV, where the ionization events were confirmed to be nuclear recoils from topology. The technique remains fully efficient down to 90 keV, decreasing to 50$\%$ at 8 keV, and reaching ($6\pm 2$)$\%$ at 1.5--3.5 keV. Irradiation with a ${}^{24}$Na $\gamma$-ray source shows no evidence of defect generation by electronic recoils, with the fraction of electronic recoils with energies $<85$ keV that are spatially correlated with defects $<0.1$$\%$.

9 pages, 7 figures

References in corpus (23)

• First Dark Matter Search Results from the LUX-ZEPLIN (LZ) Experiment
• Search for Low-Mass WIMPs with SuperCDMS
• First results from the CRESST-III low-mass dark matter program
• Single-electron and single-photon sensitivity with a silicon Skipper CCD
• DarkSide-50 532-day Dark Matter Search with Low-Radioactivity Argon
• Search for low-mass WIMPs in a 0.6 kg day exposure of the DAMIC experiment at SNOLAB
• Results from the Super Cryogenic Dark Matter Search (SuperCDMS) experiment at Soudan
• First Constraints from DAMIC-M on Sub-GeV Dark-Matter Particles Interacting with Electrons
• Results on Low-Mass Weakly Interacting Massive Particles from an 11 kg-day Target Exposure of DAMIC at SNOLAB
• Performance of the EDELWEISS-III experiment for direct dark matter searches
• Coherent Elastic Neutrino-Nucleus Scattering at the European Spallation Source
• Constraints on low-mass WIMPs from the EDELWEISS-III dark matter search
• Ionization Yield in Silicon for eV-Scale Electron-Recoil Processes
• Charge Coupled Devices for detection of coherent neutrino-nucleus scattering
• Search for coherent elastic neutrino-nucleus scattering at a nuclear reactor with CONNIE 2019 data
• Discrimination of electronic recoils from nuclear recoils in two-phase xenon time projection chambers
• Energy-Dependent Light Quenching in CaWO${}_4$ Crystals at mK Temperatures
• Precision measurement of Compton scattering in silicon with a skipper CCD for dark matter detection
• Energy loss in low energy nuclear recoils in dark matter detector materials
• Determining the bubble nucleation efficiency of low-energy nuclear recoils in superheated C${}_3$F${}_8$ dark matter detectors
• Ionization efficiency for nuclear recoils in silicon from $\sim 50$ eV to $3$ MeV
• Influence of radiation damage on the absorption of near-infrared light in silicon
• A precise method to determine the activity of a weak neutron source using a germanium detector