CCD-world: About EEV4220 and binning

[C.GUILLAUME]

The following was posted to CCD-world:

Hi all;

At OHP, we have reached the last phase of development of the new
camera dedicated to our spectrometer "Aurelie" on the 1.52m telescope.
That camera based on an EEV sensor, 4220 model, thinned, back-illuminated
and non IMO type.
We have reached a pretty good level of performances in full frame mode, or
in windowing mode, using dump drain capability, but we observe a
hard-to-understand
phenomenon using binning mode.
For example:
Using binning mode on 100 lines (dark of 1s read by right output),
we can see (on the resulting line) an increased level of about 25 e-, plus a
level break
on both right and left edges, (Cf  B100.ps or Page #1 in B100.pdf files)
which length
is a about 300 pix on both sides.

The files are available by FTP in 2 formats on the following machine:

Machine : st-iao.obs-hp.fr
Login     : ccd
Password : no password

Our trouble is due to the symetrical look of that feature.
Could it be due to a side effect? ( Mechanical ? ??)
In this case the normal mode (Cf B100b.ps or Page #2 of B100.pdf files)
would be at
a too low level to allow detection of that phenomenon?
We think it cannot be due to dark level current since it has been measured
at
0.5e-/hour/pix @ -110 Celsius.

We also observed that it seems proportionnal to the number of lines binned.

So, if somebody can explain us, it would be great...

Many thanks...

 -----------------------------
¦ Christian  GUILLAUME
¦ Michel GOILLANDEAU
¦ Service Electronique
¦   CNRS / IGRAP                                 Tel: (33).04.92.70.64.09
¦ Observatoire de Haute Provence         Fax: (33).04.92.70.64.64
¦ 04870 St Michel l'Observatoire        Email: guillaume at obs-hp.fr
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