CLAS Meeting Minutes, February 2004

  1. Volker Burkert gave the CLAS status summary
  2. Andrew Hutton gave the accelerator summary. He discussed beam delivery statistics (about 100%), beam quality problems (beam shoulder problems in Hall B have been studied and we should see improvement, especially now that they have BPMs that can see the Hall B beam) and beam energy issues (Isabel cost us several cavities, but we will be able to run at 5.7 GeV in Spetember [although with a higher trip rate]. A new cryomodule will be installed in Spring 2005 that should get us to 6.0 GeV.)
  3. CLAS business meeting:
  4. Ludyvine Morand presented her deep omega production analysis p(e,e'w).
  5. Marco Mirazita presented the search for theta+/lambda on d and 3He. gamma d -> theta+ lambda -> K+ (n) pi- p and gamma 3He -> theta+ lambda p -> ppp pi+ pi- pi-. These are very low statistics data. If we are allowed to combine several channels and both d and 3He targets, then the peak is 26 counts over a background of 26.
  6. Theta+ shootout
  7. Ken Hicks presented the results of his gamma p -> K+K+X looking for cascade peaks. There is some controversy over whether the peak at 1860 MeV seen by CERN NA49 is real. Ken doesn't see it in his data.
  8. Matt Bellis presented his data on two pion photoproduction from the proton, looking for missing resonances. He fit lots of partial waves to his very comprehensive data set and does not see evidence for new states (although his results are quite sensitive to many known states).
  9. Victor Mokeev presented his model of real and virtual two pion production from the proton. It includes many resonant and nonresonant channels. He showed that it is consistent with both Marco Ripani's electroproduction data and Matt Bellis's photoproduction data when he includes a new state (or a drastically modified existing state) at 1720 MeV. The photoproduction data is consistent with this new state since a) most of the strength in this region is nonresonant and b) there is a cancellation between the resonant terms and the interference between the resonant and nonresonant terms.
  10. Boris Ishkanov presented plans for the CLAS data database.
  11. Vipuli Dharmawardane presented the eg1 (polarized electrons on polarized p and d targets) results, concentrating on the inclusive channels.
  12. Alexei Klimenko presented the results for electron scattering from a high momentum neutron in deuterium d(e,e'p_s).
  13. Working Group Reports
  14. Curtis Meyer presented his kinematical fitting routine. The idea is to use our prior knowledge of particle masses and other constraints to optimize kinematics within each event. This should improve peak widths. When applied to peaks, if it broadens the peak then something is wrong. Peaks in low statistics samples must be robust to be believed.
  15. Cole Smith presented his Low Q^2 N -> Delta and P_11 studies. He extracted sigma_LT and sigma_TT from the data. The sigma_LT' (beam spin asymmetry) appears to be sensitive to the Roper P_11(1440) for very forward angle pions.
  16. Simon Taylor presented the radiative decays of hyperons. The old data was sparse and/or inconsistent. Hyperon radiative decay is sensitive to the quark wave function. He extracted the radiative decay widths for cascade(1385) and lambda(1520) decays to lambda+gamma. This is a VERY difficult measurement because the statistics are poor and the backgrounds are large.
  17. Coordinating Committee Report - Larry Weinstein: