Weekly Minutes 2008-03-28
From PrimExWiki
Primex Meeting Friday March 28, 2008
Present in person or phone: Mark, Ashot, Liping, Dustin, Rory, Dan, Lyang, Ilia, Aron, Eric, Tulio
Secretary: Liping
(1) Ashot reported the contact person’s meeting for Hall-B experiments on March 28. The current tentative beam schedule in Hall B for the next a few years is following: the 4He target experiment by Stephen et al. and DVCS experiment in 2009; Frozen spin target by Eugene et al. and HD Ice target by Volker et. al. in 2010; then PrimEx II and EG5 two-photon exchange experiments in 2011. Ashot raised several arguments to run PrimEx II before Frozen spin target experiment in 2010: (a) this is a textbook type of precision experiment requiring short beam time; (b) Experimental setup is ready to go; (c) A stand-alone collaboration need run the experiment as soon as possible in order to keep the collaboration alive. The decision is that we need work closely with this group in order to run PrimEx II in 2010. We may also write a letter to Larry and Volker in the future if it is needed.
(2) Eric updated his analysis result on pi0. He applied new form factors and Omega background subtraction in his analysis. The final number for the lifetime and the error budget were not shown at the meeting, however, he promised to submit it at the collaboration meeting. Liping suggested to study empty target data, use the same MC program to study Compton or Pairproduction data in order to verify how well we understand detection efficiency and acceptance, and study the model sensitivity of lifetime by varying the theoretical inputs. Ashot Suggested: show Omega background angular distribution, error budget, a plot of fitting for lifetime extraction, cross sections for C and Pb. Tulio suggested to Monte Carlo the background.
(3) Ilia updated his pi0 analysis. He showed the figures of fitting to yield and cross sections for both C and Pb targets. He also showed that the lifetime has no sensitivity on the invariant mass binning.
(4) Pawel reported his new result on pi0 cross section by using empty target data to model the background method and the kinematical constrain method. The Primakoff cross sections extracted from both methods look in agreement; however, the nuclear processes at larger angles are different from different methods. He will investigate this issue further in order to understand the causes.
(5) Collaboration meeting will start in the afternoon on April 4 and continue in the morning of April 5.
