[Clas12_first_exp] RC meeting at 2:30

[Francois-Xavier Girod]

Dear all

I posted my study of the efficiency as well
https://logbooks.jlab.org/entry/3609841

I get the same results as Stepan with points at 45 nA and 75 nA

In addition, the absolute normalization indicates a lower efficiency. This
was already seen before in the spring data. It could indicate that some
efficiency loss is due to something other than tracking.

Best regards
FX

On Mon, Oct 15, 2018 at 12:19 PM Francois-Xavier Girod <fxgirod at jlab.org>
wrote:

> 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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