[Halld-tracking-hw] HVB - FINAL VERSION - and fADC

[Curtis A. Meyer]

Hi Fernando

    the Struck FADC with the modified HVB is fine. It appears that the 
FADC125
has a factor of two lower gain than the Struck. Perhaps there is a way 
to adjust this
in the firmware. Our original conclusions based on the data that we 
collected
with the old struck are still valid, the factor of two is between the 
two FADCs
which has caught us a little by surprise.

   Curtis
On 4/11/11 5:43 PM, Fernando J. Barbosa wrote:
> Hi Naomi,
>
> The gain was halved from the original on the modified HVB to fit the 
> amplitudes within the fADC range. From your histograms, it seems that 
> you need to double the range of the fADC with the original HVB. Correct?
>
> What caused the dramatic change? Gas? Leaks?
>
> Certainly we need to discuss this as there will most likely be an 
> impact on the FDC, if we are to have one fADC for both the CDC and the 
> FDC.
>
> Best regards,
> Fernando
>
>
>
>
> Naomi Jarvis wrote:
>> Hi Fernando and Gerard,
>>
>> I have some results with cosmics and the new fADC online here: 
>> http://www.jlab.org/Hall-D/software/wiki/index.php/New_fADC_with_cosmics
>>
>> This is still a work in progress, we can see (top row of histograms) 
>> that the gain in the new fADC is about 1/2 of that of the Struck fADC 
>> (&shaper).
>>
>> Is it possible to change the full scale range of the new fADC?
>>
>> >From previous work with the Struck fADCs, we know that the preamp 
>> output saturates at approx 0.5V (measured after the shaper), so we 
>> would only be using half the range of the ADC if we use the 
>> unmodified HVB.
>>
>> We would like to put this on the agenda for the tracking meeting on 
>> Wednesday.
>>
>> Naomi and Curtis.
>>
>>
>>
>> On Apr 8, 2011, at 1:38 PM, Fernando J. Barbosa wrote:
>>
>>> Hello,
>>>
>>> I have attached a few drawings of the final HVB. Changes from the 
>>> first version are as follows:
>>>
>>> - signal attenuation network added to each signal (back of the PCB)
>>> - location and footprint of brackets
>>> - channel numbering order to agree with fADC125 (0 through 23) (top 
>>> carries the preamp card - see HVB_FINAL_TOP_SILK.PDF).
>>> - a few minor dimensional and cosmetic improvements.
>>>
>>> I have reviewed these changes with Slava but please take a look and 
>>> let me know if you have any questions as I plan to start 
>>> procurements next week.
>>>
>>> Thanks and best regards,
>>> Fernando
>>> <HVB_FINAL_TOP_SILK.pdf><HVB_FINAL.pdf><HVB_FINAL_BOT_SILK.pdf><barbosa.vcf> 
>>>
>>


-- 
Prof. Curtis A. Meyer		Department of Physics
Phone:	(412) 268-2745		Carnegie Mellon University
Fax:	(412) 681-0648		Pittsburgh PA 15213-3890
cmeyer at ernest.phys.cmu.edu	http://www.curtismeyer.com/