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Re: Flash ADC Timing
On Mon, 19 Nov 2007, Fernando J. Barbosa wrote:
Dear all,
okay there is a whole project to setup a teststand based on coda to test
the modules and also to test all the software and other functionalities we
need here at JLab. I showed / distributed the schedule during the
electronics meeting.
Having setups at individual universities is/was not part of this. So we
have to look very careful how we want to fund this. I think that is a
topic for the wednesday meeting.
regards elke
> Date: Mon, 19 Nov 2007 13:04:46 -0500
> From: Fernando J. Barbosa <barbosa@jlab.org>
> To: beni zihlmann <bzihlman@indiana.edu>, Paul Smith <ptsmith@indiana.edu>
> Cc: Elke-Caroline Aschenauer <elke@jlab.org>,
> Matthew Shepherd <mashephe@indiana.edu>, halld-cal@jlab.org,
> Elliott Wolin <wolin@jlab.org>, Gerard Visser <gvisser@indiana.edu>,
> Ed Jastrzembski <jastrzem@jlab.org>
> Subject: Re: Flash ADC Timing
>
> Hi Beni and Paul,
>
> I am CCing Elliott just in case he is not receiving these emails but
> I will talk to him regarding the issue of ordering and setting up small
> systems for R&D. He also has information on current and future plans
> from the DAQ group at Jlab with regards to CODA and software drivers for
> the various modules.
>
> The F1TDC is VME64x compliant and can be installed on VXS crates. I
> agree it is a good idea to order VXS crates in view of future tests of
> the energy sum trigger.
>
> Is one system sufficient for tests at IU? If multiples, how many?
> Most likely Gerard will also need one or access to one.
>
> Best regards,
> Fernando
>
>
>
>
>
>
> We would also need a VME64X crate, and a single board computer with
> CODA software installed on it. An F1 TDC would also be useful, along
> with any necessary back mounted interface cards, and a trigger
> supervisor. We would want to test the energy sum trigger as soon as it
> is available; this needs a VXS crate. Will the F1 operate in a VXS crate?
>
> Elliott was looking into getting together a test setup for IU maybe two
> years ago, but nothing ever came of it.
>
> Paul
>
>
> On Nov 19, 2007, at 9:22 AM, Fernando J. Barbosa wrote:
>
> > We currently have 4 10-bit fADC-250 under tests/debugging and I don't
> > expect these will be released until early 2008. We have been
> > discussing the possibility of an engineering run, 5-10 boards, in the
> > fADC group for use by users and for testing the trigger system. Please
> > be aware that it make take up to 8 weeks before we get any new boards
> > (ordering components, PCB fabrication, assembly, test).
>
>
> beni zihlmann wrote:
> > Hi All,
> > some time ago Elliot sent around a mail asking what is needed in terms
> > of electronics on DAQ
> > at the Universities. I answered to that question that here at IU we
> > have no VME based equipment
> > at all. In particular this means NO crate, NO front end cpu (ROC), NO
> > other VME based modules.
> > This means we need a Crate, a ROC and maybe another module I do not
> > know we need to get
> > CODA running in addition to the fADC. We have computers that can be
> > used as back ends
> > to install CODA on and if the communication is done via ethernet then
> > all we need on top of that is
> > a hub and some cables that we have here at IU.
> >
> > cheers,
> > Beni
> >
> > Fernando J. Barbosa wrote:
> >> Hi Elke,
> >>
> >> That's a good idea to start thinking about requests for any sort
> >> of electronics people will need over the next few months, especially
> >> in light of CD-3.
> >>
> >> We currently have 4 10-bit fADC-250 under tests/debugging and I
> >> don't expect these will be released until early 2008. We have been
> >> discussing the possibility of an engineering run, 5-10 boards, in the
> >> fADC group for use by users and for testing the trigger system.
> >> Please be aware that it make take up to 8 weeks before we get any new
> >> boards (ordering components, PCB fabrication, assembly, test).
> >>
> >> I will be away on Wednesday, 11/21/07 for the Thanksgiving holiday.
> >>
> >> Best regards,
> >> Fernando
> >>
> >>
> >>
> >> Elke-Caroline Aschenauer wrote:
> >>> On Fri, 16 Nov 2007, Matthew Shepherd wrote:
> >>>
> >>> Fernando and Matt,
> >>>
> >>> i think we all agree test are needed we can do what was suggested in
> >>> the
> >>> report. Currently we have 5 250MHz FADCs. I suggest that on
> >>> Wednesday in
> >>> the weekly Hall D meeting we find out how many FADCs pleople might need
> >>> for test stands and than see we have to produce more.
> >>>
> >>> bye elke
> >>>
> >>>
> >>>
> >>>
> >>>> Date: Fri, 16 Nov 2007 16:46:11 -0500
> >>>> From: Matthew Shepherd <mashephe@indiana.edu>
> >>>> To: Fernando J. Barbosa <barbosa@jlab.org>
> >>>> Cc: halld-cal@jlab.org
> >>>> Subject: Re: Flash ADC Timing
> >>>>
> >>>>
> >>>> Hi Fernando,
> >>>>
> >>>> I understand the claims in the document are rather optimistic;
> >>>> however, the fact of the matter is that we probably just need timing
> >>>> resolution roughly on the scale of sampling rate to suppress beam-
> >>>> related out of time noise.
> >>>>
> >>>> If you have a real fADC that is ready for use we're happy to take it
> >>>> and get it setup and running here. This would serve many purposes --
> >>>> probably most important at this point is that we could use the real
> >>>> PMT, light guide, base, and fADC that we plan for the actual
> >>>> experiment to readout just one bar and probe the low energy threshold
> >>>> of the calorimeter using cosmic rays (and guidance from simulation).
> >>>>
> >>>> -Matt
> >>>>
> >>>>
> >>>> On Nov 16, 2007, at 3:01 PM, Fernando J. Barbosa wrote:
> >>>>
> >>>>
> >>>>> Hi Matt,
> >>>>>
> >>>>> I am familiar with those documents and I recall that at the time
> >>>>> we started developing the fADC (~2 years?), I suggested that
> >>>>> someone needed to take some real data with Paul's single-channel
> >>>>> prototype and try doing the prescribed fittings, etc. To the best
> >>>>> of my knowledge, no one in the collaboration has done that.
> >>>>>
> >>>>> Referring to the document, the algorithm relies on finding the
> >>>>> exact pulse peak and getting the two preceding samples to determine
> >>>>> the 50% time, for instance. The exact peak was determined from
> >>>>> sampling at 2.5 GHz (400 ps intervals) and fitting the data with a
> >>>>> 9th degree polynomial. The data was then "degraded" to provide the
> >>>>> equivalent of 8 or 10-bit, 250 MHz (4 ns intervals) sampling. Note
> >>>>> that the exact peak is critical for the algorithm to provide the
> >>>>> quoted resolution, although these details are missing from the
> >>>>> document.
> >>>>>
> >>>>> The real fADC, and sampling at 250 MHz, will not provide a
> >>>>> sample of the true pulse peak. I believe that such "fluctuation"
> >>>>> will degrade the effective resolution considerably. So, I suggest
> >>>>> that this needs to be checked with a real fADC, perform the
> >>>>> algorithm on real raw fADC data (offline) and determined the
> >>>>> effective resolution that can be achieved by this method. Obtaining
> >>>>> 400 ps resolution from 4 ns data points and from 10 ns pulse rise
> >>>>> times seems difficult to me. We actually may have to shape (i.e.
> >>>>> slow) the pulse to get more samples on the leading edge of the
> >>>>> pulse. Once the algorithm is well understood, it will need to be
> >>>>> implemented in a relatively simple/compact manner to fit within the
> >>>>> resources of the FPGAs or board memory. Eventually, any data that
> >>>>> is passed up the chain must be balanced with the backplane bandwidth.
> >>>>>
> >>>>> Let me suggest you set up a test with the real PMTs/bases/
> >>>>> scintillator/fiber/laser and get data with a real fADC, a TDC and
> >>>>> CFD. We could lend you one fADC-250 to get the raw data. Let me
> >>>>> know what you decide and how I can help.
> >>>>>
> >>>>> Best regards,
> >>>>> Fernando
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>> Matthew Shepherd wrote:
> >>>>>
> >>>>>> Hi all,
> >>>>>>
> >>>>>> The study I was referring to has been linked to the FCAL page here:
> >>>>>>
> >>>>>> http://www.jlab.org/Hall-D/software/wiki/index.php/FCAL
> >>>>>>
> >>>>>> This work was done about 3 years ago and claims a resolution of
> >>>>>> about ~160 ps can be achieved. This is far better than is
> >>>>>> actually needed to push down backgrounds. I think Scott had in
> >>>>>> mind another application: using the FCAL to determine the event
> >>>>>> start time. The algorithm does a transformation of the leading
> >>>>>> edge of the pulse to determine the start time and depends on
> >>>>>> having the two samples before the peak on the leading edge.
> >>>>>>
> >>>>>> I believe Paul had planned to implement this in a simple lookup
> >>>>>> table which would require about 65K of memory on the chip.
> >>>>>> Perhaps that could be optimized even more. It was never
> >>>>>> investigated in detail mainly because it seemed like something
> >>>>>> relatively easy to implement. All of these buffers will need some
> >>>>>> processing -- the drift chambers will also depend on the timing
> >>>>>> algorithms that are built into the flash ADCs.
> >>>>>>
> >>>>>> -Matt
> >>>>>>
> >>>>>>
> >>>>>> <barbosa.vcf>
> >>>>>>
> >>>>
> >>>
> >>> ( `,_' )+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=
> >>> ) `\ -
> >>> / '. | +
> >>> | `, Elke-Caroline Aschenauer =
> >>> \,_ `-/ -
> >>> ,&&&&&V Jefferson Lab +
> >>> ,&&&&&&&&: HALL-D 12C / F381 121-A Atlantic Avenue =
> >>> ,&&&&&&&&&&; Mailstop: 12H5 Hampton, VA 23664 -
> >>> | |&&&&&&&;\ 12000 Jefferson Ave +
> >>> | | :_) _ Newport News, VA 23606 Tel.: 001-757-224-1216 =
> >>> | | ;--' | Mail: elke@jlab.org Mobil: 001-757-256-5224 -
> >>> '--' `-.--. | +
> >>> \_ | |---' Tel.: 001-757-269-5352 =
> >>> `-._\__/ Fax.:
> >>> 001-757-269-6248 -
> >>>
> >>> +=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+
> >>>
> >>>
> >
>
( `,_' )+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=
) `\ -
/ '. | +
| `, Elke-Caroline Aschenauer =
\,_ `-/ -
,&&&&&V Jefferson Lab +
,&&&&&&&&: HALL-D 12C / F381 121-A Atlantic Avenue =
,&&&&&&&&&&; Mailstop: 12H5 Hampton, VA 23664 -
| |&&&&&&&;\ 12000 Jefferson Ave +
| | :_) _ Newport News, VA 23606 Tel.: 001-757-224-1216 =
| | ;--' | Mail: elke@jlab.org Mobil: 001-757-256-5224 -
'--' `-.--. | +
\_ | |---' Tel.: 001-757-269-5352 =
`-._\__/ Fax.: 001-757-269-6248 -
+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+
begin:vcard
fn:Fernando J. Barbosa
n:Barbosa;Fernando J.
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adr:Suite #10, 12B3;;12000 Jefferson Ave.;Newport News;VA;23606;USA
tel;work:757-269-7433
version:2.1
end:vcard