CCD-world:CTE of TI800 again

[MYPIXEL at aol.com]

The following was posted to CCD-world:

In a message dated 12/21/99 1:50:20 PM EST, vshal at ira.kharkov.ua writes:

<< 
 Dear Jim,
 
 Thanks very much for your reply.
 My applications are low level. The operating temperature was about -120 deg.
 We observed quasars at 4000-5000 ADU with the background at 200-400
 (gain = 0.9 e/ADU, readout noise = 11 e) in order to search for their
 variability.

**********************jj
Yikes ..  .. -120 C not good for virtual phase (based on our experience with 
them). The warmer the better because of spurious potential traps (kT allows 
signal charge to escape). Warm the sensor up !
************************jj
 
 So far as we have several images of the same field with some shifts
 I could separate the background and remove it. Such procedure drastically
 reduces the background dispersion but the star tails extended along the 
columns
 are still seen and they disappoint me very much.

 Do we really unable to correct them?

************************jj
I'm afraid not ..  . it's like defocusing the image. Again . . . try 
increasing the operating temperature up to where dark current becomes a 
problem. Why are you so cold?
***************************jj
 
 I wonder if this effect is permanent and where can I read about its details?

 SPIE and "Optical Engineering" are not readily available for use here ... 

***************************jj
I can send you a paper on spurious potential pockets (traps). Again the main 
complaint for virtual phase technology is this problem. Multi-phase CCDs are 
better suited for your application I would think.

By the way, two phase CCDs often show the problem too. Whenever implants are 
used to define potential wells. . . . watch out.

Good luck and happy new year. . .
**************************jj
 
 Vyacheslav
  >>
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