A study of astrometric distortions due to “tree rings” in CCD sensors using LSST Photon Simulator

Journal Article · Fri May 22 00:00:00 EDT 2015 · Journal of Instrumentation

DOI:https://doi.org/10.1088/1748-0221/10/05/C05027· OSTI ID:1221750

Beamer, Benjamin ^[1]; Nomerotski, Andrei ^[2]; Tsybychev, Dmitri ^[1]

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1. Stony Brook Univ., Stony Brook, NY (United States)
2. Brookhaven National Lab. (BNL), Upton, NY (United States)

Imperfections in the production process of thick CCDs lead to circularly symmetric dopant concentration variations, which in turn produce electric fields transverse to the surface of the fully depleted CCD that displace the photogenerated charges. We use PhoSim, a Monte Carlo photon simulator, to explore and examine the likely impacts these dopant concentration variations will have on astrometric measurements in LSST. The scale and behavior of both the astrometric shifts imparted to point sources and the intensity variations in flat field images that result from these doping imperfections are similar to those previously observed in Dark Energy Camera CCDs, giving initial confirmation of PhoSim's model for these effects. In addition, the organized shape distortions were observed as a result of the symmetric nature of these dopant variations, causing nominally round sources to be imparted with a measurable ellipticity either aligned with or transverse to the radial direction of this dopant variation pattern.

• Research Organization: Brookhaven National Laboratory (BNL), Upton, NY (United States)
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP)
• Grant/Contract Number: SC00112704
• OSTI ID: 1221750
• Report Number(s): BNL-108352-2015-JA; KA2301020; TRN: US1500737
• Journal Information: Journal of Instrumentation, Vol. 10, Issue 05; ISSN 1748-0221
• Publisher: Institute of Physics (IOP)
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
CCD
tree rings
LSST
PhoSim