CCD temperature control range

[Tim Hardy]

Posted to CCD-world:
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> From ccd-world-request at niu.cfht.hawaii.edu Wed Oct  7 11:50 PDT 1998
> From: "jongmin" <jongmin at keops.mgn.fr>
> To: <ccd-world at cfht.hawaii.edu>
> Subject: CCD temperature control range
> Date: Wed, 7 Oct 1998 14:26:47 +0200
> 
> I am working on a project to design a space-borne Earth imaging
> telescope system. Presently the project is in preliminary design
> stage. The imaging system has panchromatic and color imaging
> capability in visible and near IR bands. The focal plane array is not
> fixed yet but it is supposed to be Si-based CCD such as Thomson's
> TH7834. From the image target performance (SNR=100, MTF=0.1), I
> derive various design parameters' requirements. Right now my concern is
> the CCD temperature control range. The CCD works at 20+/-TBD Celcius
> degree ranges. In order to derive requirements on temperature spatial
> gradient and temporal variation, CCD thermal noise(kTC noise), dark
> current noise, and thermo-elastic effects have been evaluated. What
> else do I have to consider?


For space-borne CCDs, radiation-induced damage should be a consideration.
One of the main effects is the introduction of trapping states, whose 
activity is highly temperature sensitive.
There have been numerous studies of radiation effects. I published one about
the effect on charge transfer efficiency in IEEE Transactions on Nuclear 
Science this year (vol. 45 pp. 154-163) which has references to many others.
(I have a large stack of reprints if anyone wants one.)
Radiation damage can also cause an increase in the read noise which is
temperature sensitive. I did a study of this and can send more details 
if you are interested. In addition, radiation will increase the dark current, 
so you should keep this in mind when deciding on the operating temperature.


________________________________________________________________________

 Tim Hardy
 National Research Council Canada          E-mail: Tim.Hardy at hia.nrc.ca
 Herzberg Institute of Astrophysics        Phone:  (250) 363-0015
 5071 W. Saanich Road                      FAX:    (250) 363-0045
 Victoria, B.C.   V8X 4M6

                    http://www.hia.nrc.ca/STAFF/timh
________________________________________________________________________




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