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Title: Radiation events in astronomical CCD images

Abstract

The remarkable sensitivity of depleted silicon to ionizing radiation is a nuisance to astronomers. ''Cosmic rays'' degrade images because of struck pixels, leading to modified observing strategies and the development of algorithms to remove the unwanted artifacts. In the new-generation CCD's with thick sensitive regions, cosmic-ray muons make recognizable straight tracks and there is enhanced sensitivity to ambient gamma radiation via Compton-scattered electrons (''worms''). Beta emitters inside the dewar, for example high-potassium glasses such as BK7, also produce worm-like tracks. The cosmic-ray muon rate is irreducible and increases with altitude. The gamma rays are mostly by-products of the U and Th decay chains; these elements always appear as traces in concrete and other materials. The Compton recoil event rate can be reduced significantly by the choice of materials in the environment and dewar and by careful shielding. Telescope domes appear to be significantly cleaner than basement laboratories and Coude spectrograph rooms. Radiation sources inside the dewar can be eliminated by judicious choice of materials. Cosmogenic activation during high-altitude flights does not appear to be a problem. Our conclusions are supported by tests at the Lawrence Berkeley National Laboratory low-level counting facilities in Berkeley and at Oroville, California (180 m underground).

Authors:
; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Director, Office of Science. Office of High Energy and Nuclear Physics. Division of High Energy Physics (US)
OSTI Identifier:
791224
Report Number(s):
LBNL-49316
R&D Project: 364029; TRN: US200203%%319
DOE Contract Number:  
AC03-76SF00098
Resource Type:
Conference
Resource Relation:
Conference: Photonics West (Electronics Imaging 2002), San Jose, CA (US), 01/20/2002--01/25/2002; Other Information: PBD: 18 Dec 2001
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CAMERAS; COSMIC MUONS; GAMMA RADIATION; ASTROPHYSICS; IMAGES; CCD COSMIC RAYS HIGH RESISTIVITY FULLY DEPLETED ASTRONOMICAL LICK OBSERVATORY LAWRENCE BERKELEY NATIONAL LABORATORY

Citation Formats

Smith, A R, McDonald, R J, Hurley, D L, Holland, S E, Groom, D E, Brown, W E, Gilmore, D K, Stover, R J, and Wei, M. Radiation events in astronomical CCD images. United States: N. p., 2001. Web.
Smith, A R, McDonald, R J, Hurley, D L, Holland, S E, Groom, D E, Brown, W E, Gilmore, D K, Stover, R J, & Wei, M. Radiation events in astronomical CCD images. United States.
Smith, A R, McDonald, R J, Hurley, D L, Holland, S E, Groom, D E, Brown, W E, Gilmore, D K, Stover, R J, and Wei, M. Tue . "Radiation events in astronomical CCD images". United States. https://www.osti.gov/servlets/purl/791224.
@article{osti_791224,
title = {Radiation events in astronomical CCD images},
author = {Smith, A R and McDonald, R J and Hurley, D L and Holland, S E and Groom, D E and Brown, W E and Gilmore, D K and Stover, R J and Wei, M},
abstractNote = {The remarkable sensitivity of depleted silicon to ionizing radiation is a nuisance to astronomers. ''Cosmic rays'' degrade images because of struck pixels, leading to modified observing strategies and the development of algorithms to remove the unwanted artifacts. In the new-generation CCD's with thick sensitive regions, cosmic-ray muons make recognizable straight tracks and there is enhanced sensitivity to ambient gamma radiation via Compton-scattered electrons (''worms''). Beta emitters inside the dewar, for example high-potassium glasses such as BK7, also produce worm-like tracks. The cosmic-ray muon rate is irreducible and increases with altitude. The gamma rays are mostly by-products of the U and Th decay chains; these elements always appear as traces in concrete and other materials. The Compton recoil event rate can be reduced significantly by the choice of materials in the environment and dewar and by careful shielding. Telescope domes appear to be significantly cleaner than basement laboratories and Coude spectrograph rooms. Radiation sources inside the dewar can be eliminated by judicious choice of materials. Cosmogenic activation during high-altitude flights does not appear to be a problem. Our conclusions are supported by tests at the Lawrence Berkeley National Laboratory low-level counting facilities in Berkeley and at Oroville, California (180 m underground).},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2001},
month = {12}
}

Conference:
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