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Present: Pawel Ambrozewicz, Ilya Larin, Yelena Prok, Eugene Pasyuk, Mike Wood, Aram Teymurazyan, Li Xi-qiao, Liyang, Ashot Gasparian, Sergey Gevorkyan, Liping Gan, Dustin Woolford, Matthew Reece

On phone: Dan Sober, Tulio Rodrigues

Contents 1 Review of last meeting's minutes 2 Matthew's report on the detector alignment 3 Tulio's report on the cascade calculations regarding the π0 photoproduction on 12C 4 Analysis Notes Series 5 Xi-qiao Li has arrived from China to Jlab and will start working on data analysis 6 Upcoming October DNP meeting 7 Next Collaboration Meeting 8 Next Time

Review of last meeting's minutes

We reviewed the minutes of the Jun 15, 2007 weekly meeting as recorded by Dustin Woolford

Matthew's report on the detector alignment

Matthew presented his progress report on the detector alignment. See his talk at [[1]] The goal of this study is to know precisely the beam direction and its position on HyCal. During the study it was determined that the electron beam is affected by a magnetic field between BPM1 and BPM2, so these 2 devices cannot be used to determine the beam path. Eugene mentioned that this result is not surprising since the orbital locks are continuously changing the beam position. He suggested using 2C24 (radiator) and the gamma-profiler as 2 fixed points to determine the beam path, and then check it with the HyCal data. During this discussion a long-standing issue was resolved: the markings on the gamma-profiler correspond to the MIDDLE of the scintillators.

Tulio's report on the cascade calculations regarding the π⁰ photoproduction on 12C

Tulio posted a note with the update on investigation of the systematic errors associated with the inputs of his Monte Carlo calculations. See his talk at [[2]]. Some of the highlights:

1. The result on NI differential cross section using PWIA is consistent with the existing world data within one standard deviation
2. The systematic error (difference between the data and PWIA model) is the largest at small polar π⁰ angles, ~ 30% at 1 degree, but the absolute values of the cross section do not differ by more than 0.1 μbarn/radian.
3. The cross sections are strongly dependent on the π⁰ energy cuts, so that the double differenrtial cross sections need to be used to account properly for energy losses in the real data

Analysis Notes Series

Mark will create an analysis notes series for the reference purposes, with the access to the notes protected by a password.

Xi-qiao Li has arrived from China to Jlab and will start working on data analysis

Upcoming October DNP meeting

Three abstracts (from Eric, Pawel and Yelena) should be submitted by July 2.

Next Collaboration Meeting

Updated analysis notes should be submitted before July 10.

Next Time

1. Next secretary : Matthew
2. One agenda item: Discussion of technical papers