Re: News on the preAmp + CDC

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

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
>        _--~~--_         /
>      /~/_|  |_\~\      /      Carnegie Mellon University
>     |____________|    /        Department of Physics
>     |[][][][][][]|:= /          Wean Hall room 8404
>   __| __         |__ \            Pittsburgh, PA 15213
>  |  ||. |   ==   |  | \           USA
> (|  ||__|   ==   |  |) \
>  |  |[] []  ==   |  |   \           Tel.:   +1 412 268-6949
>  |  |____________|  |    \                  +1 412 641-9252
>  /__\            /__\     \          Fax.: +1 412 681-0648
>   ~~              ~~       \-----------------------------------