Weekly Minutes 2008-02-15
From PrimExWiki
02/15/2008 15:33 PrimEx Friday weekly meeting
Presented: Mark Ito, Eugene Pasyuk, Pawel Ambrozewicz,
Liping Gan, Ashot Gasparian, Ilya Larin,
Jiang Liyang
On phone: Dan Sober, Dan Dale, Aram Teymurazyan
Ilya is making notes, next time Pawel will make notes.
Last week's meeting review:
Pawel's analysis:
Pawel will continue studying cuts and working with background analysis.
Aram presented his Photon Flux analysis http://www.jlab.org/primex/weekly_meetings/slides_2008_02_15/photon_flux_review.pdf
Relative tagging ratio looks depends from PS current polarity. Effect looks caused by imperfect PS alignment which means different acceptance for different polarities.
Relative tagging ratio corrections might be as large as 0.7% for "most problem run group". Its contribution to flux error budget (i.e. its error) is estimated as 0.3%.
Ilya asked a technical question about flux corrections already applied. The answer was: Rel. tagging ratio correction is included in prim_ana package in a run by run basis. Clock triggers frequency is also already corrected in prim_ana. Corrections were applied in the CVS directory more than half year ago.
Lines on page 6 of the presentation are for +/-1% deviations from the mean.
In TAC analysis hits in TAC were selected within +/-5ns time window. Hardware energy cut for TAC was set at the level of few hundred MeV, exact value must be written somewhere in logbook.
Error budget summary slide (page 11 of the presentation): General recommendation was to change estimations like "small", "negligible" to exact values no matter how small they really are.
Eugene asked few questions concerning Aram's analysis note: What is the absolute TAC efficiency and how it is possible to measure it? What is a probability for an accidental hit to appear within working time window (assuming poissonian distribution of hits)? On the page 9 of the presentation number of hits VS time distribution is given. There are obvious flat and curved regions on the plot. Flat region is used for the flux analysis. The suggestion is to prove quantitatively (not only qualitatively) that used region is really flat.
Summary: Ashot: "Nice job is done, Aram!" Eugene: "Needs to be published in NIM", first time for the flux measurement with such a high precision level.
General conclusion: Ready to publish a (separate) paper about flux determination (with few minor things to do possibly remained).
Other businesses:
Next week: Ilya is scheduled for pi0 analysis overview. The note is not updated yet, Ilya promised to do it ASAP.
PrimEx collaboration meeting date is not fixed yet. The possible range is between middle of March and first week of April. The possible days are either Friday or Monday (supposed to be one day meeting).
There is still no consensus on Friday meeting time. Looks like there is no time which would fit everyone's schedule. Therefore it is decided for now to use the current time (3:30).
