Absolute measurement of the Fano factor using a Skipper-CCD

Abstract

Skipper-CCD can achieve deep sub-electron readout noise making possible the absolute determination of the exact number of ionized electrons in a large range, from 0 to above 1900 electrons. In this work we present a novel technique that exploits this unique capability to allow self-calibration and the ultimate determination of silicon properties. We performed an absolute measurement of the variance and the mean number of the charge distribution produced by 55Fe X-rays, getting a Fano factor absolute measurement in Si at 123K and 5.9 keV. A value of 0.1190(25) was found and the electron–hole pair creation energy was determined to be 3.752(2) eV. This technology opens the opportunity for direct measurements of the Fano factor at low energies.