question on the CDC/ASIC doc

[Gerard Visser <gvisser@indiana.edu>]

Hi Curtis, Yves,
	I'm reading the freshly posted document on your CDC/ASIC studies. _Now_ 
I understand (I think) that the sharp cutoff in for instance fig 2a/2b 
are the trigger threshold. But then _what_ is all that stuff below 
threshold? Are you not triggering only on the channel of interest here? 
If you're not triggering only on the channel of interest, it would 
probably be interesting now to see the total charge (integral) spectrum 
when the trigger is changed to be only on the channel of interest. (For 
some reason you've left off the total charge spectrum from the document?)
	Also, I guess you should now remove the shaper "gain" of "3" stuff, we 
are all agreed now that it is 2.2. (For "instantaneous" charge input to 
the ASIC, with little or no detector capacitance; it may be fairly 
different for other situations possibly including the real CDC.)
	Thanks,

	Gerard

p.s. Finally one more question, is the peak amplitude, such as plotted 
in fig 2, simply the highest sample point, or is it based on a fit to 
the waveform around the peak? In the former case, of course it suffers 
from the _fact_ that a sample point might be on the actual waveform 
peak, or the peak might straddle two sample points, this could make a 
10-30% random error depending on the relative time of the peak and the 
sample clock. [This is another reason why it might be better to 
concentrate on the total charge spectrum instead of the peak voltage 
spectrum in figuring the gains. At least, in my opinion.]