Re: wfd (fwd)

[Robert Carey <carey@buphy.bu.edu>]

Dear Peter,
    What's the output range on that fan-out unit?
That's the key spec, of course.

 			Rob

On Wed, 30 Nov 2005, Peter Kammel wrote:

> Dear Tim, dear Rob,
>
> To answer Tim's question:
>
> We have 15 WFDs running, as we miss a clock for number 16.
> Ideally we would run 17 WFDs, 16 for all gondolas and
> the last one #17 for
> 3 neutron detectors and the mSCA counter.
>
> As you see in the email exchange below, we did not risk
> connecting the neutron detectors (they are not read out
> at the moment). However, Dave proposed to run their
> analog signals through a LRS linear fan out, so that their
> signals are limited to the fan out range. If that's
> acceptable for Rob, we could still try to get some
> neutron detector information during this run, which would
> be extremely valuable.
>
> Good luck
>
> Peter
>
> -------------------
> Hi Peter,
> I just wanted to confirm my understanding of the wfd channel
> count. You have 4x14=60 channels instrumenting 60 of 64
> gondola channels and need one additional wfd module to complete
> this set-up. Also how many neutron counters are currently installed?
> At present are simple TDC and ADC signals being recorded
> for neutron triggers (and pre-scaled e/g triggers?).
> Cheers, Tim.
>
>
>
> ---------- Forwarded message ----------
> Date: Mon, 28 Nov 2005 14:18:31 -0600 (CST)
> From: Peter Kammel <kammel@one.npl.uiuc.edu>
> To: Robert M Carey <carey@bu.edu>
> Cc: Fred Gray <fegray@socrates.berkeley.edu>,
>     R. Prieels <prieels@fynu.ucl.ac.be>, Peter Winter <peter.winter@psi.ch>,
>     Brendan Kiburg <kiburg@one.npl.uiuc.edu>
> Subject: Re: wfd
>
> Dear Rob,
>
> No rush. If it is dangerous, we won't try it during this run and
> rather wait until Rene and Fred's FADCs are ready. BTW Rene, please
> include an input protection like diode clamps, because one never
> can exclude larger signals.
>
> Thanks for your advice
>
> Peter
>
> On Mon, 28 Nov 2005, Robert M Carey wrote:
>
>> Dear Peter,
>>     Looking at the circuit and the specs for the flash ADC,
>> this looks like a DANGEROUS idea. The problem is
>> that the front end amplifiers will happily drive signals
>> near to their voltage rails but the flash ADC differential
>> inputs have an absolute differential maximum of
>> 2 volts, while the full scale is 0.5 volts. If you want
>> to pursue this idea, I think you should fashion a diode clamp to keep
>> the input signals in the safe range. If you're not in a rush,
>> we can have someone try that here.
>>
>>                                                                 Rob
>>
>> Peter Kammel wrote:
>>
>>> Dear Rob,
>>>
>>> Thus far 15 wfd are running fine, with occasional
>>> glitches. We would need to get another clock
>>> divider from MuLan for the last clock signal.
>>> I will leave this issue to Tim, who will
>>> certainly have a careful look at the wfd
>>> performance. Our extender board is in, and
>>> Genna is ready to make detailed studies
>>> with Tim, once he arrives on Thursday.
>>>
>>> We also are considering to use the wfd
>>> with our neutron detectors. The dynamic range
>>> of the neutron detectors would be set to 3.5-4 MeV.
>>> However, there would also be 10 times higher signals
>>> coming from Michel electrons running straight
>>> through the neutron detector.
>>> Is this dangerous for the wfd? We won't try that
>>> before getting your advice and ok on this issue.
>>>
>>> Many thanks
>>>
>>> Peter
>>>
>>>
>>>
>>
>
>
>