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

[Beni Zihlmann]

Hi Gerard,
yes that is exactly the end of the readout window. So it is an artifact
from the interpolation. The closer you get to the upper edge of the
readout window the interpolation starts to go berserk. Also you see
that the drift time ends around 240. All the "grass" events beyond that
point are edge effect in the drift cell. The maximum drift time is only
about 100ns for this gas mixture of 25SCCM OF CO2 AND 225SCCM OF AR/CH4 
(95/5)
which results in about 85% Argon with 5% CH5 and 10% CO2.

cheers,
Beni


> hmm, pretty encouraging I think.
> what is happening at 310 ns, why the peak there? is this the end of the search
> window? and is there an artifact from the interpolation (as in your pulse plot
> sent earlier)? no big deal if so, this can be dealt with, but I am curious.
>
> 	- Gerard
>
> On 5/13/2011 2:24 PM, Beni Zihlmann wrote:
>> Hi Gerard,
>> attached are two pdf files. both show the drift time of wire 14
>> given as the time when crossing the threshold like a leading
>> edge discriminator as in your code for le_time(). the title of the files
>> say it in one case the interpolation is used in the other not. You see
>> that with the interpolation the drift time spectrum looks just nice.
>> Without the interpolation you see the peaking structure I talked
>> about with the peaks separated by 8ns. So your interpolation
>> algorithm does a very nice job.
>>
>> cheers,
>> Beni
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