[Halld-tracking-hw] Readout equipment

[Fernando J. Barbosa]

Hi Naomi,

Thanks.

Now, if you look at the scope pics on the wiki, say with Fe-55 at 2000V 
http://www.jlab.org/Hall-D/software/wiki/index.php/Preamp_4, you will 
notice that the max amplitude of the new preamp 4 is about 450 mV and 
for the old preamp is 1300 mV (from the pictures) or about a factor of 
2.9. So, the preamp gain ratio (old/new) is about right. The same 
conclusions apply in the case of cosmics.

Could the amplitude spectrum for the old preamp at 2050V with cosmics be 
just noise and the signals are close to channel 3500? I think you easily 
verify this quickly with the scope showing the amplitude spectrum (as 
Yves did previously).

Thanks and best regards,
Fernando

Naomi Jarvis wrote:
> Hello,
>
> we are using....
>
> Old preamp:  GPC-01 FJB JLAB 2007
> New preamp:  (Preamp4)  GPC-II  and has a little white sticker on top 
> labelled '27';  corresponds to GlueX -doc-1364 Table 2 line 2.
>
> Old cable.  (because the new one inverted the polarity of the output 
> signal, which would have meant rewriting some of our analysis 
> software, and more importantly because we only have 16 channels on the 
> shaper and the channels available to us using the new cable were not 
> suitable for tracking.  So we are not using the new cable at present.)
>
> Shaper: output polarity is +ve   All the scope traces on the preamp4 
> wiki section are shaper output.   We can set the baseline to 0V.  With 
> the old range we set it to -130mV, with the new range it is 80mV.  The 
> baseline voltages were chosen so that the pedestal lies a few standard 
> deviations above channel 0.
>
> fADC Struck SIS3320  'old range' was -0.2V to 0.9V approx, 'new range' 
> is 0.05V to 0.6V approx.    These switched by setting a flag in the 
> software, recompiling and uploading.
> As I understand it, the input voltage just has to lie within that 
> defined range, otherwise we get underflow or overflow.  If the signal 
> lies within that range, its polarity does not matter.  I don't know if 
> we can move the range window to start below -0.2V though, from looking 
> through the user guide I think not but perhaps I missed it.
>
> Best regards,
>
> Naomi.
>
>
> Fernando J. Barbosa wrote:
>> Hi Curtis, Naomi and Yves,
>>
>> Please provide a description of the readout equipment you are using: 
>> new/old preamp, new/old cable, shaper (with output pulse polarity, 
>> can offset be set at zero?), ADC (Struck, polarity, range settings, 
>> etc). I recall a few resistors would need to be changed on the Struck 
>> units to get different range and polarity settings. Is this correct?
>>
>> This would help me get a better understanding of your system.
>>
>> Thanks and best regards,
>> Fernando
>>
>>
>>
>> Curtis A. Meyer wrote:
>>> We have posted photos of both the new and the old preamplifiers
>>> and linked them to the minutes section of todays meeting.
>>>
>>>     - Curtis
>>>
>>>   
>> _______________________________________________
>> Halld-tracking-hw mailing list
>> Halld-tracking-hw at jlab.org
>> https://mailman.jlab.org/mailman/listinfo/halld-tracking-hw
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