[Halld-pid] ADC

[Beni Zihlmann]

Hi Sasha,
thanks for the info.
the cable length should not matter if the ADC gate is
sufficiently long.

cheers,
Beni
> On Friday, September 30, 2011, Beni Zihlmann wrote:
>> Hi Sasha,
>> in the link
>> https://halldweb1.jlab.org/talks/2011-3Q/ADC%20spectra%20and%20Time-walk%20corrections_files/
>> you show an ADC spectrum of a paddle PMT: adc_l_par_nottrig.gif.
>> what is the HV of the PMT set at and what type of ADC are you using?
>>
>> cheers,
>> Beni
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>>
> Beni,
>
> This particular plot is done with:
>
> 1) CAEN ADC v265 in 12-bit mode. This  corresponds to
> 0.25 pC per count
>
> 2) 10-stage PMT with a nominal gain of 1.5*10^6 (at 1750 V).
> However, it was used at 2000 V in this particular measurement.
> So, its actual gain is unknown in this case.
>
> 3) What makes things more complications is a signal attenuation
> on its way from PMT anode to the ADC due to a 50-50 splitter,
> a 50 Ohm terminator right at the PMT,  and 150ft of cable. Right now,
> I'm trying to measure what is the correction coefficient I need to apply
> to compensate for this attenuation. I should have an estimate of the
> number of photoelectrons later today.
>
> Sasha
>
>
>
>
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