Noise in TASS images

[Tom Droege]

Posted to CCD-world:
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Peter,

Thank you very much.  My problem was to determine if it is smething I am
doing or whether it is a charasteristic of the devices I am buying.  This
is a low budget project, so I am buying (out of my pocket) the devices that
I can find that are the lowest cost per square mm.  Since we are doing an
all sky survey with 14 arc second pixels, sky noise will always dominate.
The problem here was to understand what was going on so that we would not
be caught by surprise.

I find the effect mostly disappears at -30 C.  I can just make that
temperature.

Possibly EEV has some devices that we should be using?  We are buying the
CCD442A from Lockheed at $1700 each in quantity 11.  This is a 2k x 2k
device with 15 micron pixels.  We get grade 3 at that price.  We hope to be
able to buy another 30 or so devices to complete our project.  We could
handle most clocking schemes.  We will also be looking for a few thinned
devices so that we can extend the survey into the blue.  

Tom Droege

At 04:59 PM 4/30/99 +0000, you wrote:
>Posted to CCD-world:
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>
>Hi Tom
>
>     The effect you describe sounds very much like the effect of heavy metal 
>contamination in the silicon.   This has been observed by several workers, 
>but one of the first references I can remember is:
>
>Self-Analysis of CCD Image Sensors using Dark Current Spectroscopy.
>W.C.McColgin et al  (Kodak)
>1993 IEEE Workshop on Charge Coupled Devices and Advanced Image Sensors
>
>     The idea is that the heavy metal gives rise to a characteristic 
>generation centre and that a pixel contains an integral number of these 
>centres, the probability decreasing with number of centres.
>
>     These guys deliberately contaminated with Au, Co and Ni and were able 
>to discriminate Au from the other 2 by the generation rate.   I believe more 
>work  has been done since, so you may be able to identify the culprit !!
>
>Good Luck
>
>Peter Pool : EEV CCDs
> 
>
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