Minutes of the Jefferson Lab CLAS Collaboration Meeting
October 25-27, 2001
Next Meeting: February 28 - March 2, 2002 at Jefferson Lab, CEBAF Center
Five new Term Members were admitted. These are: Matt Bellis, RPI; Chris Gordon, Glasgow; Joseph Malone, Glasgow; Steffen Strauch, GWU; and Ulrike Thoma, JLab/Bonn.
The Off-Line Technical Working Group had its first formal meeting. Latifa Elouadrhiri was elected chair. The important function of this committee will be to improve the codes and the documentation so that calibration and cooking can be done more quickly and accurately, and so that new members of the Collaboration can become productive much sooner than at present. As a reminder, according to the Charter, each run group will designate an Analysis Coordinator who will meet with the Off-Line Working Group to assure coordination in this important effort.
One new CLAS Approved Analysis was accepted. "Inclusive electron scattering cross sections off the proton and neutron, and extraction of F2 moments", Maruo Taiuti and Mikhail Osipenko.
One new proposal to the January PAC was approved by the Multihadron Working Group. "Study of the coherent production of the vector mesons off the deuteron," spokespersons Stepan Stepanyan, Franz Klein, and Laird Kramer.
The meeting in general:
The meeting was attended by 61 members who signed an attendance sheet, and by at least a half dozen who did not.Bernard Mecking reviewed the progress and presented the run plan for the next year. Details of his presentation are contained in the copies of Bernard's view graphs. As pointed out by Bernard, the run plan was designed to accommodate installation of instrumentation, mostly in Hall A, and the instrumentation was not yet fully ready. Before the end of the day some of the assumptions about the readiness of the instrumentation were no longer valid, and thus the schedule may well be changed.
Swapan Chattopadhyay, Associate Director of Jefferson Laboratory for the Accelerator Division spoke about prospects for improvement of the accelerator. The push toward a fully operational 6 GeV will be slow, but steady. It is expected that operation at 5.7 GeV will become more reliable, but full, reliable 6 GeV operation may well take a few years, depending on budget. Modest improvements in polarization from the present 70 to 75% range to the 80 to 85% range can be expected. The bleed-through of beam from the Hall A bucket can be controlled with a single gun, but this mode of operation may impact the available polarization.
The run coordinators for the most recent runs g6c and g8a discussed their successes and problems. Run G6-c was largely successful, with the most frustrating problem being the frequent crash of one of the ROC's associated with the tagger. Run g8 had significant start-up problems with new apparatus (goniometer, crystal radiators, refurbished tagger), but once all the problems were worked out, the run proceeded smoothly. Ashot Gasparion talked about tests for the upcoming PRIMEX experiment. While this is not a CLAS experiment, the pair spectrometer they need to monitor their photon flux will provide a much better photon monitor for all future photon beam experiments run in CLAS. Elton Smith describe a much improved, web based on-line document system which should help data takers do their job efficiently. The final talk in the morning session was by Will Brooks, who describe a potential tagged electron pair system that could be used to determine where the drift chambers really are and what the magnetic field really is, thus hopefully eliminating many of the ad hoc empirical corrections now used.
The Thursday afternoon session was devoted to the longer range program with CLAS. The physics and the instrumentation needed to accomplish the physics were presented. Stepan Stepanyan talked about the DVCS program and Volkert Burkart explained the plans for the forward, small angle calorimeter that will be needed to make these highly rated measurement. Franz Klein and Mike Seeley discussed the program to measure double polarization variables and the frozen-spin polarized target needed to make these measurements.
On Friday morning we heard about some of the analysis now underway In spite of difficulties in fully understanding the CLAS detector progress continues to be made. It appears as if it will be difficult to explain all of the data without the inclusion of some new resonances. Hopefully, by the next Collaboration meeting the picture will be even clearer. We also heard from Maruo Taiuti concerning his request for a CLAS Approved Analysis (see above). His proposal had previously been approved by both the SoN and Multihadron Working groups, and was unanimously approved by written ballot by the entire CLAS Collaboration.
During the reports and business meeting Saturday morning, several notable points we brought out. There was a brief discussion of the rules on lead authors. The Charter states that the list of authors is to be alphabetical, except for the lead authors who will be listed in an order of their choosing. The charter does not define lead authors, which allows for the possibility of a large number of "lead authors." Should the few who actually wrote the paper be allowed to designate as many of their friends as they desire as lead authors, or should there be a limit, say two or three? There is a variety of opinion within our collaboration. The Chair announced he will entertain suggestions and comments, and make a report at the next Collaboration meeting.
We were pleased to learn from the service work committee that almost all of the institutions belonging to the CLAS Collaboration were determined to be sharing the service work on a reasonable basis.
The meeting adjourned at 12:20 pm.
Reported by Hall Crannell