[Halld-cal] Estimate of number of triggers needed for pi0 calibration

[Elton Smith]

Hi all,

This is a summary of the notes that were exchanged to estimate the number of triggers needed to have
sufficient pi0s to have 10x the amount of data for a single calibration. This will serve for calibrations
and systematic studies.


Refs: log entry
https://logbooks.jlab.org/files/2016/01/3370103/fall2015_pi0_firstlook_1.pdf
and
http://argus.phys.uregina.ca/gluex/DocDB/0029/002900/002/Cal_update_jan16.pdf

Runs: 4318, 4319, 4323, 4399, 4400, 4401, 4404, 4405

Will estimates we need 50k pi0s for a calibration of layers 1-3. For the
fall 2015 run, we have 58k pi0s for Eg>700 MeV. Data corresponds to 9
hours of data.

Elton counted the number of triggers in all runs is 76 M events based on
https://www.jlab.org/Hall-D/test/RunInfo/

-> Ratio of raw events / pi0 events (Eg>700 MeV) = 76 M / 58 k = 1300.

-> For pi0 calibration, we need 50k x 1300 events = 65 M triggers. For
fall 2015 data rate, this would be about (65 M / 76 M) * 9 hours = 8
hours of data.

For increased DAQ speed to 10kHz (mode 7), the time would be 65 M /
10kHz = 6500 s ~ 2 hours of data, or 3 kHz (mode 8) ~ 6 hours of data.

Assuming we take 450k pi0 events = 585M triggers in mode 7 @ 10KHz = 59,000 s = 16 hours
Assuming we take 50k pi 0 evens = 65M triggers in mode 8 @ 3Khz = 22,000 s = 6 hours

-> Need about 22 hours of actual data taking to accumulate the desired statistics for pi0 calibrations.


  --
Elton Smith
Jefferson Lab MS 12H3
12000 Jefferson Ave STE 4
Newport News, VA 23606
(757)269-7625
(757)269-6331 fax