Confirmation of the spectral excess in DAMIC at SNOLAB with skipper CCDs

Citations Over TimeTop 10% of 2024 papers

Abstract

We present results from a $3.25\text{ }\text{ }\mathrm{kg}\text{\ensuremath{-}}\mathrm{day}$ target exposure of two silicon charge-coupled devices (CCDs), each with 24 megapixels and skipper readout, deployed in the DAMIC setup at SNOLAB. With a reduction in pixel readout noise of a factor of 10 relative to the previous detector, we investigate the excess population of low-energy events in the CCD bulk previously observed above expected backgrounds. We address the dominant systematic uncertainty of the previous analysis through a depth fiducialization designed to reject surface backgrounds on the CCDs. The measured bulk ionization spectrum confirms the presence of an excess population of low-energy events in the CCD target with characteristic rate of $\ensuremath{\sim}7$ events per kg-day and electron-equivalent energies of $\ensuremath{\sim}80\text{ }\text{ }\mathrm{eV}$, whose origin remains unknown.

Related Papers

• → A 16 Mfps 165kpixel backside-illuminated CCD(2011)46 cited
• → Where Are the X-Ray Event Grades Formed Inside the Pixel of the Charge-Coupled Device? The Behavior of the Primary Charge Cloud Inside the Charge-Coupled Device(1998)29 cited
• → Nonlinear time dependence of dark current in charge-coupled devices(2011)4 cited
• → Studies on the measurement of charge transfer efficiency and photoresponse nonuniformity of linear charge-coupled devices(1995)3 cited
• → Charge-Coupled-Device and Charge-Injection-Device Theory and Application(1987)1 cited