[Halld-tracking-hw] ADC125 as a TDC...

[Beni Zihlmann]

Hi Gerard,
I did not answer your first question so here it is:
In all the plots showed I do not apply a common mode subtraction. I only
determine an average pedestal for each channel over the first 15 samples
and subtract this value from each sample. Then I use your code to calculate
the time of the LE threshold where the threshold is 350 counts.

cheers,
Beni


> 	Cool. I don't really understand how it can make that much difference, but good
> (I guess) that it does.
> 	By the way, I have a question, is the common-mode correction applied first
> before the timing algorithm? And could you show us where is the LE threshold on
> a cathode pulse height spectrum made from the earliest strips only (i.e. the
> ones used here in your timing histograms)? I'm still fishing for info whether
> the timing threshold is reasonable or really maybe I should say whether it looks
> feasible to set a good threshold.
> 	Thanks!
>
> 		- Gerard
>
> On 5/17/2011 11:57 AM, Beni Zihlmann wrote:
>> Hi Gerard,
>> thanks for the idea. I took only the fastest trip for each preamp card.
>> had here the result. This cleans up the spectra dramatically. Also you
>> can see that for a given card the timing seems to drift for groups of
>> strips. In particular strip 1 ot 24 you see a distinctive wiggle.
>>
>> cheers,
>> Beni
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