[Halld-tracking-hw] Tracking Meting Tomorrow

Mon Apr 18 11:08:17 EDT 2011

My preamp arrived a little while ago, I am trying it out.

Thanks,

Naomi.

On Mon, April 18, 2011 9:19 am, Fernando J. Barbosa wrote:
> Hi Naomi, Gerard,
>
>
> I have attached a brief doc on the impulse response of the preamp. I
> think it should work well with the CDC setup.
>
> Best regards,
> Fernando
>
>
>
>
>
> Fernando J. Barbosa wrote:
>
>> Hi Naomi, Gerard,
>>
>>
>> I have configured and tested the preamps as I described earlier
>> (should have a short doc later) and they are shipping to each of you
>> today via FedEx. You should have them on Monday.
>>
>> Best regards,
>> Fernando
>>
>>
>>
>>
>>
>> Naomi Jarvis wrote:
>>
>>> Great!  That should work nicely.
>>>
>>>
>>>
>>> Thanks,
>>>
>>>
>>> Naomi.
>>>
>>>
>>>
>>> On Thu, April 14, 2011 9:29 am, Fernando J. Barbosa wrote:
>>>
>>>
>>>> Hi Naomi,
>>>>
>>>>
>>>>
>>>> Yes, the changes (removing terminating resistors at the output of
>>>> the preamp) will be on the preamp. We still need the modified HVB to
>>>>  attenuate the charge into the ASIC. So, the CDC will have the
>>>> preamp configured with low gain (~0.6 mV/fC - the setting you have
>>>> now), no terminating resistors on the preamp output, modified HVB and
>>>> fADC125. One fADC125 will be used with both the CDC and the FDC and
>>>> as it is now.
>>>>
>>>> 14-bit ADCs are not on the plans.
>>>>
>>>>
>>>>
>>>> Best regards,
>>>> Fernando
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> Naomi Jarvis wrote:
>>>>
>>>>
>>>>
>>>>> Hi Fernando,
>>>>>
>>>>>
>>>>>
>>>>> you do mean the preamp and not the HVB, right?   I already
>>>>> collected cosmics with the unmodified HVB (without the
>>>>> attenuators) to see if the resolution would be any different, it
>>>>> does look better (pics on the wiki, tracking mtg agenda) but we do
>>>>> still need to use the modified HVB
>>>>> to fit the dynamic range we want into the preamp.
>>>>>
>>>>> What about using 14-bit ADCs ?
>>>>>
>>>>>
>>>>>
>>>>> Naomi.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> On Apr 13, 2011, at 7:47 PM, Curtis A. Meyer wrote:
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>> Hi Fernando -
>>>>>>
>>>>>>
>>>>>>
>>>>>> please do send us one of these preamp cards -- thanks ..
>>>>>> curtis On 4/13/11 5:22 PM, Fernando J. Barbosa wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>> Hi Gerard,
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> OK, I will send you two preamps (CDC and FDC).
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> There is an easy way to double the pulse amplitude at the
>>>>>>> input of the ADC which is to remove the back-terminating
>>>>>>> resistors on the preamp card. This would not change the preamp
>>>>>>> response . This change would not require any changes to the
>>>>>>> fADC125 and one version would still fit both detectors as this
>>>>>>> is already the consensus at JLab. I can send a preamp to Naomi
>>>>>>> in this configuration for tests.
>>>>>>>
>>>>>>> Best regards,
>>>>>>> Fernando
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> Gerard Visser wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>> Hi Fernando,
>>>>>>>> Thanks, I will change the gain setting as you say.
>>>>>>>> Could you please still send me another board in CDC
>>>>>>>> configuration? First of all this one is set for cathodes and
>>>>>>>> I
>>>>>>>> might not have enough 0402 jumpers to convert to anodes
>>>>>>>> operation, and secondly this board has apparently all
>>>>>>>> channels dead on the middle ASIC and I worry perhaps could
>>>>>>>> have an abnormal response on the others (I don't know what
>>>>>>>> the cause of the trouble is). In any case, having two boards
>>>>>>>> to be able to confirm the measurements on the second unit, I
>>>>>>>> think will be a good idea. If you have 'plenty' then please
>>>>>>>> also send one in FDC cathode configuration (same reasons). I
>>>>>>>> have updated my slide with a 2nd one showing the waveforms
>>>>>>>> at the ADC output terminals. With the caveat this is as you
>>>>>>>> say for quite the wrong gain selection on the ASIC, the
>>>>>>>> results of this test look to me to indicate the linearity
>>>>>>>> is really worse than it looks on the ADC125 view, the
>>>>>>>> maximum reasonably linear pulse height is about 43% of full
>>>>>>>> scale on the ADC. We'll have to see how this looks with
>>>>>>>> the correct gain setting on the ASIC. My updated slides are
>>>>>>>> here
>>>>>>>> http://npvm.ceem.indiana.edu/~gvisser/GlueX/ADC_scale.pdf
>>>>>>>> Sincerely,
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> Gerard
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> p.s. And the answer to Curtis' question from the other day
>>>>>>>> "Does
>>>>>>>> the input of the FADC-125 match the 0V to 0.5V output of the
>>>>>>>> ASIC,
>>>>>>>> or is it something else?": For pulses of this shape, the
>>>>>>>> input of the ADC125 matches to an amplitude of 990mV, which
>>>>>>>> is indeed probably higher than intended (sorry). HOWEVER
>>>>>>>> care is certainly needed - for _wider_ pulses the ADC125
>>>>>>>> full scale will be _lower_ in amplitude (it is a shaper...).
>>>>>>>> [And I presume the CDC can get
>>>>>>>> some pretty wide pulses when tracks pass at an angle.]
>>>>>>>>
>>>>>>>>
>>>>>>>> On 4/13/2011 2:54 PM, Fernando J. Barbosa wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>> Hi Gerard,
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> The preamp you have is set for a gain of 3.2 mV/fC and a
>>>>>>>>> dynamic range of 110 fC (@ 5% linearity), quite different
>>>>>>>>> from the CDC. This is the fifth row in the Table 2 of
>>>>>>>>> GlueX-doc-1364
>>>>>>>>> (the CDC is set as per the second row -
>>>>>>>>> 0.57 mV/fC,
>>>>>>>>> DR=380 fC).
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> I attach the preamp configuration settings showing where
>>>>>>>>> the resistors are to be installed. To set your preamp to
>>>>>>>>> the CDC configuration, move the resistor to the left of
>>>>>>>>> the RC label to the pads on the right (5.1 Ohm resistor
>>>>>>>>> sets RC to logic 1) and move the resistor to the left of
>>>>>>>>> the HG label to the pads on the left (5.1 Ohm resistor
>>>>>>>>> sets HG to logic 0).
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> The FDC cathode setting is the sixth row in Table 2 (2.6
>>>>>>>>> mV/fC gain). Let me know if this works for you as this
>>>>>>>>> changes are easy to make with a soldering iron. If not, I
>>>>>>>>> will send you another preamp(s).
>>>>>>>>>
>>>>>>>>> There is GlueX-doc-1570 showing the dynamic range with
>>>>>>>>> the HVB and shows good linearity.
>>>>>>>>>
>>>>>>>>> Best regards,
>>>>>>>>> Fernando
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Gerard Visser wrote:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>> the preamp strapping picture (for current discussion)
>>>>>>>>>> http://npvm.ceem.indiana.edu/~gvisser/GlueX/straps.jpg
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>> --
>>>>>> 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/
>>>>>>
>>>>>>
>>>>>>
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>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>
>>>
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>