Re: FEU84-3

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

Hi Matt,

We have clock distribution boards that output multiple (five) NIM 
replicas and were designed for providing synchronized clocks to multiple 
fADCs on a small setup. These were recently designed by Gerard and Kim 
and are available with 250 MHz clocks. These sources include the power 
supply.

If these are of interest to you, we can ship you one now.

Regards,
Fernando

Matthew Shepherd wrote:
>
> Hi all,
>
> I think the reason for the slow rise time is that Mihajlo was running 
> the PMT at a pretty low voltage (much lower than the nominal operating 
> point) because the light source was pretty bright.  We are reworking 
> the setup to have a dimmer source and we will crank up the voltage on 
> the tube.  This should tighten the timing of the leading edge.
>
> This is not the only "bug" we're trying to work out.  We also 
> anticipate a problem due to the fact that we have single channel fADCs 
> which have their own clocks.  Because the clock freq. is not exact 
> there may be some phase drift between the two that introduces a +-4 ns 
> jitter in the triggers sent to each card.  We will let you know how 
> things progress -- we have ideas also for how to work around this.
>
> -Matt
>
>
> On Apr 8, 2008, at 10:58 AM, Fernando J. Barbosa wrote:
>> Hi Eugene,
>>
>> The numbers you quote are about what I expected. Perhaps Mihajlo 
>> (sorry I don't have his email) could find out what is causing such a 
>> slow pulse from the laser as that really impacts the ultimate timing 
>> resolution that can be achieved with the flash, after pulse fitting.
>>
>> Thanks and regards,
>> Fernando
>