[clas12_rgk] trigger efficiency vs ECal treshold
Viktor Mokeev
mokeev at jlab.org
Wed Dec 12 23:04:40 EST 2018
Dear FX,
Anyway, I checked examples with the numerical results you mentioned in your e-mail. The check outcome is attached. My and your results coincide. So, we are on the same page. I just don't know how to read your nomogram. I was unable to get points from them in your examples...
Best Regards,
Victor
________________________________
From: clas12_rgk <clas12_rgk-bounces at jlab.org> on behalf of Viktor Mokeev <mokeev at jlab.org>
Sent: Wednesday, December 12, 2018 10:20:34 PM
To: Francois-Xavier Girod-Gard
Cc: Rafayel Paremuzyan; clas12 rgk; clas12 first exp
Subject: Re: [clas12_rgk] trigger efficiency vs ECal treshold
Dear FX,
I am not sure I understand your plots. We need to speak. I can do this tomorrow afternoon.
Best Regards,
Victor
________________________________
From: Francois-Xavier Girod <fxgirod at jlab.org>
Sent: Wednesday, December 12, 2018 9:54:55 PM
To: Viktor Mokeev
Cc: clas12 rgk; clas12 first exp; Rafayel Paremuzyan
Subject: Re: [clas12_rgk] trigger efficiency vs ECal treshold
Dear Viktor
I have those series of over-informative plots as attached in case they can help the discussion
They show the kinematic coverage for a given beam energy
Units are GeV and degrees. For instance, the points
( Q^2 = 2 , W = 3 ) corresponds to approximately ( mom = 1.1 , theta = 30 )
( Q^2 = 5 , W = 2.5 ) corresponds to approximately ( mom = 1 , theta = 53 ) (this point is off scale on the plots)
The 35 degree angle at W = 2.5 occurs around Q^2 = 3.8 and mom = 1.6
Best regards
FX
On Wed, Dec 12, 2018 at 6:26 PM Viktor Mokeev <mokeev at jlab.org<mailto:mokeev at jlab.org>> wrote:
Dear All,
From FX trigger efficiency plot, I see efficiency problems at the lab. energies of the scattered electron <2.0 GeV or for \nu value above 5.5 GeV for the electron beam energy 7.5 GeV. It corresponds to the following W ranges where we have the problem with trigger efficiency:
Q^2=2.0 GeV^2 W>3.0 GeV
Q^2=5.0 GeV^2 W>2.5 GeV
For hybrid baryon search, we have no any problem with the trigger efficiency at Q^2<2.0 GeV^2 since the lightest hybrids are expected in the mass range <2.5 GeV. Furthermore, the initial search for hybrid baryons will be carried out at Q^2<2.0 GeV^2.
Best Regards,
Victor
________________________________
From: Francois-Xavier Girod <fxgirod at jlab.org<mailto:fxgirod at jlab.org>>
Sent: Wednesday, December 12, 2018 6:09:53 PM
To: Viktor Mokeev
Cc: clas12 rgk; clas12 first exp; Rafayel Paremuzyan
Subject: Re: [clas12_rgk] trigger efficiency vs ECal treshold
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<mailto: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<mailto:clas12_rgk-bounces at jlab.org>> on behalf of Francois-Xavier Girod <fxgirod at jlab.org<mailto:fxgirod at jlab.org>>
Sent: Wednesday, December 12, 2018 5:58:01 PM
To: clas12 rgk; clas12_first_exp at jlab.org<mailto: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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