Astronomical Spectroscopy with Skipper CCDs: First Results from a Skipper CCD Focal Plane Prototype at SIFS

Conference · Fri Aug 09 04:00:00 EDT 2024

DOI:https://doi.org/10.2172/2429325· OSTI ID:2429325

Villalpando, Edgar Marrufo; Roach, Brandon; Bonati, Marco; Drlica-Wagner, Alex

We present the first on-sky results from an ultra-low-readout-noise Skipper CCD focal plane prototype for the SOAR Integral Field Spectrograph (SIFS). The Skipper CCD focal plane consists of four 6k $$\times$$ 1k, 15 $$\mu$$m pixel, fully-depleted, $$p$$-channel devices that have been thinned to $$\sim$$250 $$\mu$$m, backside processed, and treated with an anti-reflective coating. These Skipper CCDs were configured for astronomical spectroscopy, i.e., a single-sample readout noise $< 4.3$$\,e$$^-$$\,rms/pixel, the ability to achieve multi-sample readout noise $$\ll 1\,$$e$$^-$$\,rms/pix, full-well capacities $$\sim$40,000--65,000 e$^-$, low dark current and charge transfer inefficiency ($$\sim 2$$ $$\times$$ $$10^{-4}$$ e$^-$/pixel/s and 3.44 $$\times$$ $$10^{-7}$$, respectively), and an absolute quantum efficiency of $$\gtrsim 80\%$$ between 450\,nm and 980\,nm ($$\gtrsim 90\%$$ between 600\,nm and 900\,nm). We optimize the readout sequence timing to achieve sub-electron noise ($$\sim 0.5$$\,e$^-$$\,rms/pix) and photon-counting ($$\sim 0.22$$\,e$$^-$$\,rms/pix) readout noise over an area of 2k $$\times$ 4k and 110 $$\times$$ 4k pixels, respectively in a readout time of $$\lesssim 17$$min. We observed two Lyman-$$\alpha$$ emitting quasars (HB89\,1159$$+$$123 and QSO\,J1621$$–$$0042) at redshift $$z \sim 3.5$$, two moderate redshift galaxy clusters (CL\,J1001$$+$$0220 and SPT-CL\,J2040$$-$$4451), an emission line galaxy at $z = 0.3239$$, a candidate member star of the Bo\"{o}tes~II ultra-faint dwarf galaxy, and five CALSPEC spectrophotometric standard stars (HD074000, HD60753, HD106252, HD101452, HD200654). We present charge-quantized, photon-counting observation of the quasar HB89\,1159$$+$$123 and show the detector sensitivity increase for faint spectral features. We demonstrate signal-to-noise performance improvement for SIFS for observations in the low-background, readout-noise-dominated regime. We outline preliminary scientific studies that will leverage the SIFS-Skipper CCD data to derive new cosmological measurements in the context of dark matter and galaxy evolution.

• Research Organization: Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
• Contributing Organization: AstroSkipper
• DOE Contract Number: AC02-07CH11359
• OSTI ID: 2429325
• Report Number(s): FERMILAB-SLIDES-24-0128-V; oai:inspirehep.net:2816583
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS