Re: Tagger Fixed Array & Pair Spectrometer Electronics Update

["Fernando J. Barbosa" <barbosa@jlab.org>]

Hi Franz,

Thanks for your reply. I will update the Hall D system information with 
this information.

Regards,
Fernando





Franz Klein wrote:
>
> Fernando,
>
> I apologize to have left your mail without response for such a long time.
>
> See below my answers to your questions (I will add paragraphs on
> electronics requirements to the Gluex wiki:
> http://www.jlab.org/Hall-D/software/wiki/index.php/Photon_Beam_Design_Requirements 
>
>
> Franz
>
> On Thu, 28 Feb 2008, Fernando J. Barbosa wrote:
>
>> Hi Franz,
>>
>> I have requested this information before but I have received no updates,
>> yet.
>>
>> I am updating the information on the electronics system diagram for all
>> Hall D detectors. I would appreciate if you could provide some feedback.
>>
>> Tagger Fixed Array:
>> 1. Are passive splitters appropriate for the fixed spectrometer (PMTs)?
>> Passive (resistive) splitters will cut the amplitude of the signal in
>> half (TDC and ADC) but the S/N is maintained.
>
> We use passive splitters for the fixed spectrometer: the signals are 
> large
> enough.
>
>> 2. Are leading edge  discriminators appropriate for the fixed 
>> spectrometer?
>
> We want to keep it with CFDs in order to be able to adjust gains for high
> luminosity runs without loosing the timing accuracy.
>
>> 3. Is 60 ps resolution (LSB) sufficient?
>
> That resolution is enough: we have to test some prototypes first but my
> guess is a timing resolution of 100-150psec.
>
>> 4. Recently, the fADC250 requirements have been changed to 12-bit. Is
>> this appropriate?
>
> That is fine with us!
>
>> Pair Spectrometer:
>> 1. Is the PMT used the XP2020?
>
> Currently we use the Hall-B spectrometer as placeholder for our design
> that is being developed in cooperation with Yerevan Physics Inst.
> Hall B has Hamamatsu R6427 and XP2020 might be fine as well. I don't know
> about the scintillator widths for Hall D yet.
>
>> 2. Is 60 ps resolution (LSB) sufficient?
>
> Yes: here the timing is less important than for the tagger hodoscope.
>
>> Thanks for your attention.
>>
>> Regards,
>> Fernando
>>
>
> ===============================================================
>                  Franz J. Klein, Associate Professor
>                  CUA, Department of Physics
>                  Washington, DC 20064
>  office: Hannan Hall 206          phone: 202-319-6190
>  or: Jefferson Lab,CC F-243       phone: 757-269-6671
> ---------------------------------------------------------------
> ------------------------------------------------------------------------
>
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> tel;work:757-269-7433
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>   
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