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Re: First look at GlueX Preamp response with FDC



HI Everyone -

Thanks for the update on things, it is indeed good that you see the preamp
working. To date, all the suggestions that have been made with regard to the
CDC have not worked. It may very well be a big grounding issue, but probably not
at all different from what we will face in the final chamber. This is something that
we need to resolve (and our solution may well be relevant to a full sized FDC).

    Yves will be heading to Europe later this week, so our plan is to collect a
very large data set with cosmics using the CLAS preamp over the next
couple of weeks to try and pin down the timing resolution in the chamber.

    We are also planning to instrument a third HV board using components
as suggested by people in the recent discussion.I am sure that this will have
no impact on the noise issues, but it may help us capture a bit more signal.
(Decoupling part with 330pF and 10k-Ohm), protection resistors at 1M-Ohm
and input filter caps at 1nF (we don't have 3nF available).)

    When Yves is back, we will return to the ne preamp and 3rd HV board to
look at things.

        cheers -- Curtis 

On Mon December 17 2007, Simon Taylor wrote:
> Hello, everyone.
> 
> Fernando and I looked at real signals from the FDC prototype using the
> GlueX preamp boards this afternoon.  The pulses were generally quite large
> to the point of possibly saturating the output of the shaper board I am
> using to look at the signals.  The noise level was low.
> I have put some photographs of scope traces on the web in the FDC logbook
> at
> http://www.jlab.org/htbin/PHYSICS/halld/enote112.pl?nb=notebook&action=view&page=348
> 
> Simon
> 



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