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Re: News on the preAmp + CDC
Hall D Electronics:
Yes, it was a very productive day. There were a number of issues
with the grounds on cables that we learned about today, and even
the DC power supply that I had (that was not cheap) was noisy.
This leads me to wonder if we should try to "spec out" a reasonable
low-noise DC suppy that can be used in the experiment. Gerard
liked HP's, but Fernando's input would also be useful. I would like
to try and purchase one so we are closer to the final configuration.
I would also note that to date we have not used Gerard's shaper.
He was putting a connector on for it this afternoon, but I believe that
all of the pulses are without it.
cheers - curtis
On Mon January 21 2008, Fernando J. Barbosa wrote:
> Hall D Electronics:
>
> Hi Yves,
>
> It looks like you and Gerard are making quite a lot of progress with the
> FDC. The pulses look reasonable but there is still some work left in
> trying to understand the source of the oscillations you observed before.
>
> I also looked at the drift time spectra at different sampling rates that
> you obtained. The time structure of the main pulse is similar and of the
> order of 200 ns. There shouldn't be any aliasing as the pulse structure
> out of the preamp is already over 10 ns. However, there seems to be some
> reflection or after pulsing, as the 200 MSPS picture clearly shows. If
> you are using the shaper, check if this is not an artifact from the
> shaper. Gerard may have chosen the shaping constants based on the CLAS
> preamp. I and Simon observed a similar characteristic with the anode
> shaper on the FDC.
>
> Regards,
> Fernando
>
>
>
> Yves Van Haarlem wrote:
> > Hi Fernando,
> >
> > Gerard is now looking at the CDC setup with the new preAmp. First
> > findings can be found on the CDC wiki (it looks much better now):
> >
> > http://www.jlab.org/Hall-D/software/wiki/index.php/CDC_23_01_2008
> >
> > ("news on the preAmp" part)
> >
> > Cheers,
> > Yves
> >
> >
> > /--------------------------------
> > / Yves Van Haarlem
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> > /~/_| |_\~\ / Carnegie Mellon University
> > |____________| / Department of Physics
> > |[][][][][][]|:= / Wean Hall room 8404
> > __| __ |__ \ Pittsburgh, PA 15213
> > | ||. | == | | \ USA
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> > | |____________| | \ +1 412 641-9252
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--
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/