CCD-world: Rockwell Hawaii question - stars abound !

[Peter Moore]

The following was posted to CCD-world:


Dear Colleagues,

I am currently characterising a Rockwell 1024x1024 MCT array for use in
our NIR imager INGRID due to be commissioned soon (to soon :-).
(see http://www.ing.iac.es/IR/INGRID/ingrid1_home.htm)

I am experiencing problems of high noise due to very many hot pixels that
are spatially stable. I am using a basic cds (reset - read - integrate -
read) scheme running on a sdsu controller for readout. The number of hot
events depends on some threshold that seems to be linked with the number
of reads performed (more reads, more stars). The amplitude is significant
(6K - 20K ADU at Vrst 0.55v) and can be varied using the reset voltage. If
I hold the reset on while reading there are no events, if I switch the
reset clock off, the events reach 60K ADU. I'm using offboard FET source
followers with the onboard biasgate FET set to 3.4v and the biaspower at
5.2v. Holding the reset gate on and moving Vrst to 0v also surpesses the
events.

Peeking between the events the noise floor is good at around 12e- rms.
Response and linearity are good to about 100K e- at 4e-/ADU gain. 

I'm thinking it has something to do with the current flowing through the
horizontal mux switch but what to do about it is driving me nuts :-)

Any help on this problem would be very much appreciated !

Best regards to all of you,
	Peter.
  
=+===+===+===+===+===+===+===+===+ ING +===+===+===+===+===+===+===+=
 =     Peter Moore, Isaac Newton Group, La Palma Observatory, Spain.     =
=   E-mail pcm at ing.iac.es                  Voice Office +34 922 405566    =
=   S-mail Apartado de Correo 321,           Fax Office +34 922 405646    =
=          38780 Santa Cruz de La Palma,     Voice Home +34 922 435042    =
 =         Canary Islands, Spain.                                        =
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