Single-electron and single-photon sensitivity with a silicon Skipper CCD (1706.00028v1)

Abstract: We have developed a non-destructive readout system that uses a floating-gate amplifier on a thick, fully depleted charge coupled device (CCD) to achieve ultra-low readout 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. This allows the precise counting of the number of electrons in each pixel, ranging from pixels with 0 electrons to more than 1500 electrons. The resulting CCD detector is thus an ultra-sensitive calorimeter. It is also capable of counting single photons in the optical and near-infrared regime. Implementing this innovative non-destructive readout system has a negligible impact on CCD design and fabrication, and there are nearly immediate scientific applications. As a particle detector, this CCD will have unprecedented sensitivity to low-mass dark matter particles and coherent neutrino-nucleus scattering, while astronomical applications include future direct imaging and spectroscopy of exoplanets.

Single-Electron and Single-Photon Sensitivity with a Silicon Skipper CCD

The paper presents a significant advancement in the performance and capabilities of charge-coupled devices (CCDs), specifically focusing on a novel Skipper CCD. The research introduces a non-destructive readout system utilizing a floating-gate amplifier to achieve a low readout noise level of 0.068 e¯. This development signifies a substantial step forward in precision measurements, allowing for the precise counting of electrons within each pixel of a CCD, from as few as 0 electrons to over 1500 electrons, positioning this Skipper CCD as an ultra-sensitive calorimeter.

Technical Overview

The Skipper CCD achieves this low noise through multiple, independent, non-destructive measurements of the charge in each pixel. This method significantly reduces low-frequency readout noise. Traditional CCDs are limited by readout noise, but the technology described here overcomes this limitation, reaching a noise level that enables precise single-electron counting over a large silicon detector format.

A noteworthy innovation is the Skipper CCD’s dynamic capability to adjust the number of samples per pixel, allowing for optimized readout noise on a case-by-case basis. Specifically, the paper reports that with 4000 samples per pixel, a noise level of 0.068 e¯ is achievable, facilitating sub-electron noise, which is pivotal in various scientific applications.

Implications for Particle Physics

In particle physics, the Skipper CCD holds promise for low-mass dark matter detection and coherent neutrino-nucleus scattering, both of which have previously faced challenges due to the limitations in CCD sensitivity and readout noise. The ability to count individual electrons precisely at a threshold as low as 2-3e¯ significantly enhances the detector's sensitivity to dark matter particles, including those interacting with electrons in silicon or coherent interactions with nuclei.

Applications in Astronomy

Astronomical applications of this technology are equally promising, particularly in areas such as exoplanet research. Space-based imaging missions seeking to characterize terrestrial exoplanets could benefit immensely from the Skipper CCD’s low noise, aiding in the detection of weak signals with reduced exposure times.

The low readout noise capability will facilitate the paper of variable sources and enable advancements in time-domain astronomy, although improvements in readout speed are necessary to fully exploit this potential application.

Future Prospects and Conclusion

The introduction of the Skipper CCD establishes a new benchmark for low-noise detection in large-area silicon detectors. Future work may focus on enhancing the readout speed to broaden the range of practical applications further and exploring configurations with additional amplifiers to decrease overall readout time.

This paper meticulously delineates not only the technological advances achieved but also delineates the broad scope of future scientific inquiries. The Skipper CCD emerges as a highly versatile tool poised to significantly impact both the realms of particle physics and astronomy. By offering ultra-low noise and dynamic sampling capabilities, it provides the foundational bedrock upon which future detailed investigations into rare event phenomena and faint astronomical signals could be built, each potentially reshaping our understanding of fundamental physics and the universe.