[clas12_rgk] trigger efficiency vs ECal treshold

[Francois-Xavier Girod]

Dear Viktor

Rafo can confirmed as he produced the plot, my understanding is that the
electron momentum is measured by the drift chambers

Best regards
FX

On Wed, Dec 12, 2018 at 6:08 PM Viktor Mokeev <mokeev at jlab.org> wrote:

> Dear FX,
>
>
>  Just to make sure, whether P on your plots is the energy=momentum of the
> scattered electron?
>
>
> Best Regards,
>
>                                     Victor
> ------------------------------
> *From:* clas12_rgk <clas12_rgk-bounces at jlab.org> on behalf of
> Francois-Xavier Girod <fxgirod at jlab.org>
> *Sent:* Wednesday, December 12, 2018 5:58:01 PM
> *To:* clas12 rgk; clas12_first_exp at jlab.org
> *Cc:* Rafayel Paremuzyan
> *Subject:* [clas12_rgk] trigger efficiency vs ECal treshold
>
> Dear all
>
> During today's meeting I attempted to have a discussion on the trigger
> efficiency as function of ECal threshold. Contradicting statements were
> made during the meeting, so I want this discussion to be on record here.
>
> Please see the plot
>
> https://www.jlab.org/Hall-B/secure/clas12/rec_mon/P_Good_emWithEC_5786.png
>
> from Rafo's study of the trigger efficiency. He analyzed run 5786 which
> was taken with the random trigger.
>
> - in blue all "good electrons" with Nphe>2, E_PCal > 60 MeV, sampling
> fraction > 0.2 and fiducial cuts
>
> - in orange, the electrons satisfy in addition E_ECal > 300 MeV
>
> - in red, the events for which the orange set was missing the electron
> trigger bit
>
> The trigger efficiency is defined as (orange - red) / orange
>
>
> https://www.jlab.org/Hall-B/secure/clas12/rec_mon/Eff_All_Good_em_trg_threshold_5786.png
>
> The trigger efficiency below 2 GeV drops rapidly, and measuring a cross
> section in this region is challenging
>
> My question during the meeting was: do we already have data to show the
> trigger efficiency when the threshold is 150 MeV. My understanding is that
> we do not have this data and that to answer this question we need to take
> another random trigger run with the lower threshold.
>
> What I have in mind is the following: I agree that the bulk of the RG-K
> data taking can take place at 300 MeV ECal trigger threshold and highest
> possible luminosity, but I would like to consider the possibility to take a
> few days at a lower trigger threshold to extend the cross section
> measurement  to higher W. Again my purpose is to minimize the final
> systematic uncertainties.
>
> Best regards
> FX
>
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