Charge-Collection Efficiency in Back-Illuminated Charge-Coupled Devices

Fernandez-Moroni, Guillermo; Andersson, Kevin; Botti, Ana Martina; Estrada, J.; Rodrígues, D.; Tiffenberg, J.

doi:10.1103/physrevapplied.15.064026

Cited by 15 publications

(11 citation statements)

References 20 publications

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“…Our PCC profile, obtained from the measured properties of minority-carrier transport in silicon (details in Appendix A), was experimentally confirmed with direct measurements using a 55 Fe x-ray source in Ref. [82]. High levels of hydrogen were also measured in the ISDP layer.…”

Section: Discussionsupporting

confidence: 72%

Characterization of the background spectrum in DAMIC at SNOLAB

Aguilar-Arevalo,

Amidei,

Arnquist

et al. 2021

Preprint

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We construct the first comprehensive radioactive background model for a dark matter search with charge-coupled devices (CCDs). We leverage the well-characterized depth and energy resolution of the DAMIC at SNOLAB detector and a detailed GEANT4-based particle-transport simulation to model both bulk and surface backgrounds from natural radioactivity down to 50 eVee. We fit to the energy and depth distributions of the observed ionization events to differentiate and constrain possible background sources, for example, bulk 3 H from silicon cosmogenic activation and surface 210 Pb from radon plate-out. We observe the bulk background rate of the DAMIC at SNOLAB CCDs to be as low as 3.1 ± 0.6 counts kg −1 day −1 keV −1 ee , making it the most sensitive silicon dark matter detector. Finally, we discuss the properties of a statistically significant excess of events over the background model with energies below 200 eVee.

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Section: Discussionsupporting

confidence: 72%

Characterization of the background spectrum in DAMIC at SNOLAB

Aguilar-Arevalo,

Amidei,

Arnquist

et al. 2021

Preprint

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“…The contribution from radiative recombination of electron-hole-pairs created in the doped layer in the backside of the CCD is subject to large systematic uncertainties due to bandgap narrowing effects in that region of the apparatus, which affects charge diffusion. In our "fiducial" model for the bandgap narrowing in the backside, which reproduces well data on the partial charge collection [26] from the backside, radiative recombination contributes negligibly to the 1electron rate. However, with a more "extreme" model for the bandgap narrowing, the contribution to the 1-electron rate from radiative recombination can even dominate over that from Cherenkov; however, the extreme model does not reproduce well the partial charge collection data.…”

Section: Introductionsupporting

confidence: 67%

Sources of Low-Energy Events in Low-Threshold Dark-Matter and Neutrino Detectors

Egaña-Ugrinovic

Essig

et al. 2022

Phys. Rev. X

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The reach of sub-GeV dark-matter detectors is at present severely affected by low-energy events from various origins. We present the theoretical methods to compute the single-and few-electron events that arise from secondary radiation emitted by highenergy particles as they pass through detector materials and perform a detailed simulation to quantify them at (Skipper) CCD-based experiments, focusing on the SENSEI data collected at Fermilab near the MINOS cavern. The simulations account for the generation of secondaries from Cherenkov and luminescent recombination radiation; photo-absorption in the bulk, backside layer, pitch adapter, and epoxy; the photon reflection and refraction at interfaces; thin-film interference; the roughness of the interfaces; the dynamics of charges produced in the highly doped CCD-backside-layers; and the partial charge collection on the CCD backside. We consider several systematic uncertainties, notably those stemming from the backside modeling, which we estimate with a "fiducial" and an "extreme" charge-diffusion model, with the former model being preferred due to better agreement with partial-charge collection data. We find that Cherenkov photons constitute about 40% of the observed single-electron events for both diffusion models; radiative recombination contributes negligibly to the event rate for the fiducial model, although it can dominate over Cherenkov for the extreme model. We also estimate the fraction of 2-electron events that arise from 1-electron event coincidences in the same pixel, finding that the entire 2-electron rate can be explained by coincidences of radiative events and spurious charge. Accounting for both radiative and non-radiative backgrounds, we project the sensitivity of future Skipper-CCD-based experiments to different dark-matter models. For light-mediator models with dark-matter masses of 1, 5, and 10 MeV, we find that future experiments with 10-kg-year exposures and successful background mitigation could have a sensitivity that is larger by 9, 3, and 2 orders of magnitude, respectively, when compared to an experiment without background improvements.

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“…Rates of single electron depositions larger than expected have been observed in [8], and its possible link to higher-energy particles has been summarized in [14]. Moreover, recent studies on regions in the CCD with low collection efficiency [15] show how large-energy ionization events could produce low-energy signals in the detector. For this reasons, experiments running above ground are more challenging due to the larger rate of atmospheric high-energy particles [16,17].…”

Section: Thick Fully Depleted Ccds For Particle Detection Experimentsmentioning

confidence: 98%