[G12] Beam Intensity vs MOR rate - G12_wiki

[Valery Kubarovsky]

So called "live time corrections" applied twice by M. Williams is
nonsense.
CLAS has no problem with live time corrections. g11 group found that the
normalized to the photon flux yield is current dependent. Accidentally this
correction was found to be very close to the live time correction. However
it doesn't mean
that the reason for inefficiency at high current is live time. Personally I
think that
at high current we have problem with the track reconstruction inefficiency
due to
the background hits in DC, TOF etc. e1-dvcs study of this phenomena showed
that
including the background hits (measured by CLAS) to MC data decreases the
track
reconstruction efficiency by about 15% for 2 track events. it affects all
high intensity
CLAS experiments.

The g12 trigger has no dead time at all.
The only week signal in the g12 trigger is signal MOR. If this logical
signal has no dead time
(as it is supposed to be) we do not have problem with g12 trigger.

Valery


On Tue, Feb 8, 2011 at 3:04 PM, Eugene Pasyuk <pasyuk at jlab.org> wrote:

> Gflux was not corrected for anything and I don't see what is there to
> correct.
> This is a misconception that the live time correction has been applied
> twice. It is true that g11 discovered necessity to apply additional rate
> dependent correction to the cross section. In fact g11 was the only run
> that had to do that.
> EG3 was running with very high intensity as well I am not aware they
> needed to do something similar to what g11 did.
> I believe the problem is not in the live time but in the rate dependent
> trigger inefficiency and it turned out that this correction
> quantitatively is similar to the live time correction. G11 had other
> trigger inefficiency corrections as well.
>
> Do you need to apply additional corrections to g12 cross sections? I
> don't know the answer. This has to be studied.
> Just to remind you, photon flux is just one out of several ingredients
> for the cross section. You also have to look at yield extraction,
> acceptance, trigger efficiency etc.. The hardware trigger setup for g12
> was completely different compared to g11.
>
> -Eugene
>
> On 02/08/11 10:03, Paul Eugenio wrote:
> > Hi Eugene,
> >
> > We are looking into several issues we have regarding cross section
> estimates.  One concern we have is with the photon normalizations.   I agree
> that the MOR is not the viable estimate of any intensity depend sag to the
> live time.  G12 ran with the highest photo intensity of any run, and earlier
> studies using g11 data showed a gflux calculated live time which had a
> dependence on the beam flux.    In order to correct this, the live time
> corrections where applied twice (as shown by M. Williams).    I do not know
> if gflux code was corrected or if it needed to be corrected.   Should we
> apply this correction twice for g12?
> >
> >
> > --
> > Prof. Paul Eugenio
> > Florida State University
> > Department of Physics
> > Tallahassee, Florida,  USA 32306
> >
> > (850) 644-2585
> > eugenio at fsu.edu
> >
> >
> >
> > On Feb 8, 2011, at 9:38 AM, Eugene Pasyuk wrote:
> >
> >> We also have individual EPICS scalers for every tagger PMT.
> >> They are better monitor than MOR.
> >>
> >> -Eugene
> >>
> >>
> >> On 02/08/11 09:33, John Price wrote:
> >>> Sounds like we need the output of gflux as a function of beam
> current...
> >>>
> >>> On Tue, 2011-02-08 at 06:29 -0800, Eugene Pasyuk wrote:
> >>>> MOR rate is not reliable intensity monitor. It is logical OR, it is
> NOT
> >>>> arithmetic sum of all counters.
> >>>> It saturates and eventually goes down when you increase flux.
> >>>>
> >>>> -Eugene
> >>>>
> >>>>
> >>>> On 02/08/11 09:24, Paul Eugenio wrote:
> >>>>> Hi,
> >>>>>
> >>>>> I dug out the data from the beam intensity study which was done
> during the run.    Performing a linear fit to the first few points shows
> that at 60 nA the MOR rate sags by about 8%.
> >>>>>
> >>>>>
> http://clasweb.jlab.org/rungroups/g12/wiki/index.php/Beam_Intensity_vs_MOR_rate
> >>>>>
> >>>>> --
> >>>>> Prof. Paul Eugenio
> >>>>> Florida State University
> >>>>> Department of Physics
> >>>>> Tallahassee, Florida,  USA 32306
> >>>>>
> >>>>> (850) 644-2585
> >>>>> eugenio at fsu.edu
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>> _______________________________________________
> >>>>> G12 mailing list
> >>>>> G12 at jlab.org
> >>>>> https://mailman.jlab.org/mailman/listinfo/g12
> >>>> _______________________________________________
> >>>> G12 mailing list
> >>>> G12 at jlab.org
> >>>> https://mailman.jlab.org/mailman/listinfo/g12
> >> _______________________________________________
> >> G12 mailing list
> >> G12 at jlab.org
> >> https://mailman.jlab.org/mailman/listinfo/g12
> >
> > _______________________________________________
> > G12 mailing list
> > G12 at jlab.org
> > https://mailman.jlab.org/mailman/listinfo/g12
> _______________________________________________
> G12 mailing list
> G12 at jlab.org
> https://mailman.jlab.org/mailman/listinfo/g12
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: https://mailman.jlab.org/pipermail/g12/attachments/20110208/d943416c/attachment.html