[Halld-tracking-hw] ASIC procurement deadline

[Curtis A. Meyer]

Hi Fernando -

   give us a chance to finish the measurements we are doing. The scope 
traces are a bit
misleading because both preamps are saturating at different levels. This 
the new one looks
smaller because the output is limited by the preamp to be smaller, not 
necessarily the gain.
We are collecting data for a configuration where neither is saturating 
to check.

   We also still have the issue of the amplitudes of the cosmic signal. 
The "lower peak" for
the old preamp cannot be noise, unless you believe that there are 
hundreds of channels of
noise in the system, we saw about 10, so that does not make sense. There 
is still an
inconsistency in the measurements that we are making and we need to 
understand that.

    How long will it take? I don't have a good answer at the moment. The 
measurements that
are most sensitive take 24 to 48 hours per point and we don't know how 
many points we
need. That (sadly) adds up fast.

     We need to do the following:
     - measurement with a tilted chamber with the new (and possibly the 
old preamp).
     - complete the efficiency curve with the new preamplifier.
     - collect enough statistics at an optimal point so that we can 
track and plot with tracked
       parameters. This could take up to a week.

     Something is very odd with the new preamplifier on the CDC and we 
are very uncomfortable
with it right now.

   - curtis
On 6/14/10 9:07 PM, Fernando J. Barbosa wrote:
> Curtis,
>
> WOW! That's a lot of exclamations - glad they are not expletives.
>
> Look at the results you just placed on your wiki, look at the scope 
> signals, look at amplitude spectra. What else do you need to be 
> convinced of the fact that the gains are as expected? There is even a 
> statement confirming that fact that was just placed on the wiki .You 
> can verify the ASIC performance using the test setup described in 1364 
> if you so desire. I stand by my results!
>
> I completely agree that you need to understand the behavior of the CDC 
> and you will need more time for that - no question about that. 
> Certainly, I won't start procurements until the CDC and the FDC groups 
> understand the performance of the detectors with the ASIC.
>
> I just need an estimate of the completion date. Is this much to ask, I 
> ask?
>
> Best regards,
> Fernando
>
>
>
> Curtis A. Meyer wrote:
>> Fernando -
>>
>>   
>> NO!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! 
>>
>> We do NOT buy off on the gain being lower yet!!!!!!!!!!!!!!!!!!!!!!!!!!
>> We are still working on more measurements to understand what is going
>> on. Please do not jump the  gun on 
>> this!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
>> We have to be able to get PHYSICS out of the CDC and we have to
>> make sure that things are 
>> right!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
>>
>>    Curtis
>>
>> On 6/14/10 6:33 PM, Fernando J. Barbosa wrote:
>>> Hi Curtis and Lubomir,
>>>
>>> Now that we all agree that the gain on the new preamp is lower than 
>>> the on the old one, I would appreciate if you could provide me with 
>>> an estimate to complete your studies with the CDC and the FDC with 
>>> regards to the ASIC and preamp.
>>>
>>> May I suggest July 4th for the deadline?
>>>
>>> Thanks and best regards,
>>> Fernando
>>
>>


-- 
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/