Re: shaper gain

["Curtis A. Meyer" <cmeyer@ernest.phys.cmu.edu>]

Hi Gerard -

 thanks for the comment on the ADC range. I am not sure what we need to
do, but it would certainly be better to match as much of the linear range
of the ASIC to that of the Flash-ADC.  While we can probably correct for
the lon linear part as we move above the charge limit, I suspect that those
corrections are probably temperature dependent. While this may not be
a problem, we probably want to think about this up front.

   Curtis
On Mon July 28 2008, Gerard Visser wrote:
> Hi Fernando,
> 	Oh, one other point, and this is maybe worthwhile for others to 
> consider too. The present "anode" setup of the shaper board, I believe, 
> puts the full scale of the ADC at roughly 770 fC (instantaneous input 
> charge, e.g. Fe55), as documented on page 2 of 
> http://argus.phys.uregina.ca/gluex/DocDB/0007/000736/003/Receiver_Shaper_Setup_for_GPC01.pdf
> 	In other words, the "good linear range" of the ASIC is presently about 
> 39 to 52% of the ADC range, depending on what you call "good".
> 	With the proposed change, the "good linear range" of the ASIC should 
> then be about 8 to 10 % of the ADC range. I'm not sure this is really 
> what we want to do... (Although of course we can try it and see. I could 
> be proved wrong!)
> 
> 	Gerard
> 
> Gerard Visser wrote:
> > Hi Fernando,
> >         Ok, just to check, this will be setting the gain 1/5 of the present
> > "anode" shaper gain, is that correct? (If not, please say...)
> ...
> 



-- 
Professor Curtis A. Meyer        Department of Physics
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