[Clas12_first_exp] RC meeting at 2:30

[Francois-Xavier Girod]

Dear all

If the Figure of Merit for N particles is parameterized as function of the
beam current I in terms of an intercept A and a slope B such that
F.O.M. = I x ( A - B x I )^N
then the optimal beam current is
I_best(N) = A / [ B x ( N+1 ) ]

For instance with B = 0.00485
I_best(N=1) = 103 nA
I_best(N=2) = 69 nA
I_best(N=3) = 52 nA

The optimal beam current is directly proportional to the efficiency at zero
beam current.

Best regards
FX

On Sun, Oct 14, 2018 at 6:34 PM Stepan Stepanyan <stepanya at jlab.org> wrote:

> Hello Mac,
>
> No argument, 45 nA will be fine. As you noticed, my “efficiency” and the
> figure-of-merit plot that shows peak at 50 nA for 3-prong events assume
> 100% tracking efficiency for beam current =0. Of course it is not true, so
> the real optimum is bit less than 50 nA.
>
> Regards, Stepan
>
> > On Oct 14, 2018, at 12:03 PM, Mac Mestayer <mestayer at jlab.org> wrote:
> >
> > Good work - now negatives and positives give
> > the same results.
> >
> > Regarding the optimum - you optimized for production
> > rate, but I'd like to point out that there will be
> > a systematic error associated with the efficiency
> > correction, and this error is probably proportional
> > to the size of the correction.
> >
> > Sorry to be a bummer and bring up systematic errors !  :{
> >
> > Anyway, that effect and the fact that the drift chambers
> > are running fairly high DC HV currents, would argue for
> > ~ 45 nA maximum, in my opinion.
> >
> > regards, Mac
> >
> > ----- Original Message -----
> > From: "Stepan Stepanyan" <stepanya at jlab.org>
> > To: "clas12 first exp" <clas12_first_exp at jlab.org>
> > Sent: Saturday, October 13, 2018 10:14:23 PM
> > Subject: Re: [Clas12_first_exp] RC meeting at 2:30
> >
> > Dear all,
> >
> > I run the same studies for tracking efficiency using positively and
> negatively charged track multiplicity at different currents. The beam
> current dependence of tracking efficiency is improved compared to previous
> studies with data processed in August. Details can be found at -
> > https://logbooks.jlab.org/entry/3608949
> >
> > Optimum beam current for 3-prong evens is 50 nA.
> >
> > Stepan
> >
> >
> >
> >
> >
> > On Oct 8, 2018, at 3:04 PM, Francois-Xavier Girod < fxgirod at jlab.org >
> wrote:
> >
> > Dear all
> >
> > In the logbook the path indicated to the data files for the luminosity
> scan set is incorrect
> >
> > The correct path for the 2 nA files are
> > /work/clas12/clas12/data/fall18/cooked/out_clas_pin_004893.evio.*.hipo
> >
> > The other runs are in the same directory, the runs are
> > 4893 2 nA
> > 4895 4 nA
> > 4887 10 nA
> > 4888 25 nA
> > 4956 45 nA
> > 4900 60 nA
> > 4899 75 nA
> >
> > Best regards
> > FX
> >
> > On Mon, Oct 8, 2018 at 7:38 PM Rafayel Paremuzyan < rafopar at jlab.org >
> wrote:
> >
> >
> > Hi all,
> >
> > sorry for late notice,
> >
> > We will have an RC meeting today at 2:30 PM to
> > discuss the status and plans for the run.
> > The room is the meeting room in the 2nd floor in the counting house.
> > Bluejeans linkhttps:// bluejeans.com/7572697303
> >
> > Rafo
> > RC
> >
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> >
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>
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