Constraints on the electron-hole pair creation energy and Fano factor below 150 eV from Compton scattering in a skipper CCD

A. M. Botti*, S. Uemura, G. Fernandez Moroni, L. Barak, M. Cababie, R. Essig, E. Etzion, D. Rodrigues, N. Saffold, M. Sofo Haro, J. Tiffenberg, T. Volansky

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


Fully depleted thick silicon skipper-charge-coupled devices (skipper CCDs) are an important technology to probe neutrino and light-dark-matter interactions due to their subelectron read-out noise. However, the successful search for rare neutrino or dark-matter events requires the signal and all backgrounds to be fully characterized. In particular, a measurement of the electron-hole pair creation energy below 150 eV and the Fano factor are necessary for characterizing the dark matter and neutrino signals. Moreover, photons from background radiation may Compton scatter in the silicon bulk, producing events that can mimic a dark matter or neutrino signal. We present a measurement of the Compton spectrum using a skipper CCD and a Am241 source. With these data, we estimate the electron-hole pair-creation energy to be (3.71±0.08) eV at 130 K in the energy range between 99.3 eV and 150 eV. By measuring the widths of the steps at 99.3 eV and 150 eV in the Compton spectrum, we introduce a novel technique to measure the Fano factor, setting an upper limit of 0.31 at 90% C.L. These results prove the potential of skipper CCDs to characterize the Compton spectrum and to measure precisely the Fano factor and electron-hole pair creation energy below 150 eV.

Original languageEnglish
Article number072005
JournalPhysical Review D
Issue number7
StatePublished - 1 Oct 2022


FundersFunder number
ERC-CoG-2015682676 LDMThExp
Fermi Research Alliance, LLC
U.S. Department of EnergyDE-AC02-07CH11359
Office of ScienceDE-AC02-05CH11231
High Energy Physics
Horizon 2020 Framework Programme682676
Heising-Simons Foundation623940, 79921
European Research Council
United States-Israel Binational Science Foundation2020220
Israel Science Foundation1862/21


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