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Re: Cross talk
Hi Fernando,
> You are right, I was thinking of cosmics for the coincidence trigger or
> perhaps Sr90 and the coincidence to remove accidentals/background. Did you
> ever get a Sr90 source?
We do have some weak Sr-90 sources - i never did measurements with them,
but Curtis might have before I was here. I could do measurements with
the Sr-90 source later on.
Cheers,
Yves
>
> Regards,
> Fernando
>
>
>
>
>>
>> Cheers,
>> Yves
>>
>> /--------------------------------
>> / Yves Van Haarlem
>> _--~~--_ /
>> /~/_| |_\~\ / Carnegie Mellon University
>> |____________| / Department of Physics
>> |[][][][][][]|:= / Wean Hall room 8404
>> __| __ |__ \ Pittsburgh, PA 15213
>> | ||. | == | | \ USA
>> (| ||__| == | |) \
>> | |[] [] == | | \ Tel.: +1 412 268-6949
>> | |____________| | \ +1 412 641-9252
>> /__\ /__\ \ Fax.: +1 412 681-0648
>> ~~ ~~ \-----------------------------------
>>
>> On Thu, 19 Jun 2008, Fernando J. Barbosa wrote:
>>
>>> Hi Yves,
>>>
>>> I looked at the plots you just posted and I have a few questions.
>>>
>>> For crosstalk, you are plotting the peak amplitude distributions for the
>>> whole data run, I believe. You need to compare the peak amplitudes on an
>>> event-by-event basis, e.g., compare peak amplitude on ch1 to ch2 for event
>>> 1, and repeat for the other events. The best way to do this is to get a
>>> scatter plot. Applying a fit to the scatter plot, should yield a straight
>>> horizontal line (or vertical) [meaning independence between channels] for
>>> zero crosstalk or a line with a slope for any crosstalk. The slope is the
>>> crosstalk, say volts in ch1 to volts in ch2. You will need a plot for each
>>> channel adjacent to the straw with the source.
>>>
>>> For the raw ADC data, one event per plot, it seems that the noise is very
>>> low and that is a good thing. Now, when you take this data and plot the
>>> amplitude distribution do you apply a threshold cut? For instance, I see
>>> that the baseline or pedestal is at about ADC channel 650 - do you exclude
>>> all the samples below this value? It would also be interesting to see how
>>> the amplitude distributions change with different threshold cuts.
>>>
>>> For the "energy" plots, it seems that these plots follow the same trend as
>>> those plots under "Different-HV" which is good. But I still don't
>>> understand why the shape - it should look like a Poisson distribution or
>>> more properly a Landau distribution. What I see is that the low level
>>> amplitude tail gets proportionally smaller with increasing HV, as a result
>>> of perhaps higher S/N ratio. This may be artificial, of course, due to
>>> higher occurrence of limited streamer pulses or higher gain (more signals
>>> above the trigger threshold).
>>>
>>> It would be nice if you could form a trigger by using the coincidence of
>>> two overlapping straws, as I mentioned in a previous email.
>>>
>>> Regards,
>>> Fernando
>>>
>>>
>>>
>>>
>>> Yves Van Haarlem wrote:
>>>> Hi All,
>>>>
>>>> As a follow up from the meeting this after noon. I posted some
>>>> peak-amplitude spectra on the wiki concerning cross talk. One can see
>>>> that there is some measurable electronic cross talk between adjacent
>>>> channels on the HV-board.
>>>>
>>>> http://www.jlab.org/Hall-D/software/wiki/index.php/ASIC_design_optimizations#Cross_talk
>>>>
>>>> Cheers,
>>>> Yves
>>>>
>>>> /--------------------------------
>>>> / Yves Van Haarlem
>>>> _--~~--_ /
>>>> /~/_| |_\~\ / Carnegie Mellon University
>>>> |____________| / Department of Physics
>>>> |[][][][][][]|:= / Wean Hall room 8404
>>>> __| __ |__ \ Pittsburgh, PA 15213
>>>> | ||. | == | | \ USA
>>>> (| ||__| == | |) \
>>>> | |[] [] == | | \ Tel.: +1 412 268-6949
>>>> | |____________| | \ +1 412 641-9252
>>>> /__\ /__\ \ Fax.: +1 412 681-0648
>>>> ~~ ~~ \-----------------------------------
>>>>
>>>
>