CCD read-noise, Roger Smith Enq.

[Paddy Oates]

Roger,
	Hi. We measure routinely 3.5e on a Tek1024 CCD. At 173K, by doing stats
on two identical images to work out the electronic gain and then converting
our sigma sq. to noise rms e. The CDS time is 70us/pixel and 20+20 integrator
slopes. This ISNT the lowest noise I have seen quoted. John Barton at AAO
has a table of CCD read-speeds versus noise and he can get 2ish at LONG
pixel times - 320us/pixel I think. His stuff was published in an AAO 
newsleter a while ago. Drain current 1.0mA, no CREs, underscan used for
bias subtraction, dark current 0 for the ms integration of the 2 exposures-
done with some pre-flash LEDs on the chip PCB in the dewar. Gain 1.2e/adu

	The lowest noise we can get, to convince you that we are (just about
at present) detector noise limited is 2.5e with the new EEV 15/11 series chips
which I am currently trying to quantify with EEV in terms of its 300-400nm
response-  these are to be the flag-ship EEV units (27/13.5um, 
1024x256/2048x512 pixels) for large area devices. The read-noise of these 
devices appears to be best at twice our normal read-out rate (35us/pixel, 
10+10us integrator slopes) and with a low drain current, 0.3mA, I have measured 
one chip at around 2e rms. All 'standard' operating conditions, non MPP, 
T=150K.. Gain 0.3e/adu... Sensitivity of FET 3uV/e.


Cheers,
Paddy Oates
RGO
UK
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