Single Electron per Pixel Counting with Fully Depleted Charge Coupled Devices

Scientific grade Charge Coupled Devices (CCDs) show attractive capabilities for the detection of particles with small energy deposition in matter. Here we present new developments on a novel readout technology known as Skipper-CCD that uses a readout stage that allows for multiple non-destructive sampling of the charge packets. These multiple samples can be averaged reducing the RMS of the noise with the square root of the number of samples taken. By averaging 4000 samples per pixel we are able to reach an unprecedented deep subelectron noise of 0.068 e
_rms
^-
/pix. This is the first time that discrete sub-electron readout noise has been achieved reproducibly over millions of pixels on a stable, large-area detector (A~7 cm
²
). We discuss the design aspects, clocking and electronic readout noise optimization of the device. This device has a wide range of applications: ultra low threshold particle detection, celestial and laboratory spectroscopy, exoplanets searches and life science.