Sebastian Kuhn

Overview:  I discussed the result of the Readiness Review (basically a delay of one month) and the resulting new schedule for the CLAS Physics program. We lost most of our 1.833 GeV running time. After some discussion (during and after the meeting), we decided to change 7 days of 4 GeV running and 10 days of 3 GeV running to 2.03 GeV, to maintain our fraction of low-energy running at roughly 50%. Other issues discussed: The "helicity scheme" (see email discussion) and the trigger. We might want to use a tighter trigger (1 photoelectron threshold for the Cerenkov, separate thresholds for inner calorimeter and total sum, TOF and, if possible, 2^nd level). This needs to be studied using E1 data.

Dan Sober

Real Photon Part: Dan reminded us of the proposed parameters and expected results for the real photon part of EG1. It seems that with 2 "ideal" days (100% efficient) one can do a publishable experiment on the asymmetry E1. We will use the 2.03 GeV running at the end for that purpose.

Don Crabb

Polarized Target: Don reported on the acceptance test at Oxford Instr. and future work. Target is cooled down and leaktight in the EEL and acceptance test here seems to be on schedule. Don and Mike Seely will produce a detailed task list for the next 2 months by the beginning of May.

Marco Anghinolfi

Genoa Report: Marco reported on (and showed) the final stick design with NMR coils. After optimization, TE signals for the deuteron could be measured. All looks well! Some discussion on 12C background target. We need 0.6 g/cm2, evenly distributed throughout an "authentic" target cell.

Dan Carman

Møller Update: Dan reported on the status of the Møller polarimeter. His talk has been overtaken by the most recent events (not his fault): The latest test run on Sunday April 26 was a smashing success; the measured polarization behaved exactly as expected. The polarimeter should be perfected in time for the July run of g1 (see the new schedule).

Volker Burkert

Beam Line Hardware: Volker reported progress on the rastering scheme and other beam line elements. The rastering apparatus will be tested in the EEL in May/June. Everything is on track for an August run.

Ralph Minehart

Møller Background Studies with GSIM: Ralph reported on the UVa simulation of Møller background. The lead shield design has been optimized and the background should be less than for normal (unpolarized) running. See Dale Conwell's report.

Dave Doughty

Trigger: Dave presented the Level 2 trigger status. It looks like if we require only 4 hits per DC region and only 2 out of 3 regions, the trigger will be nearly 100% efficient, help a lot with data rate reduction, and can be ready for our run.

Mark Ito

EPICS: Mark gave an overview over the structure of EPICS applications and some of the challenges one faces when introducing new devices.

Arne Freyberger

Slow Controls and DAQ Interface: Arne discussed the integration of several devices into the CLAS control/DAQ system. The Polarimeter poses the largest amount of (unidentified) labor so far. Karen White might be able to make the individual EPICS drivers happen, but Arne beliefs we need an overall GUI for non-experts (which may be done by Sergei, I believe). Sergei will also work on the integration of the Møller DAQ. The Beam raster system also requires a lot of EPICS work, which will be supplied by Scott Higgins (acc. Div.).

There are presently 3 ways envisioned to normalize to beam intensity. The Faraday cup scaler can be used, but should have 100x higher sensitivity. The nA-BPMs need to be synchronized with helicity reversal and integrated in the data stream (should we also use scalers here?) Finally, we could have a thin foil as dedicated Møller luminosity target.

Dieter Cords

Data acquisition: Dieter discussed the work underway to increase the data rate (no numbers mentioned) and to integrate helicity information and beam counters into the DAQ. The helicity state is read for every event using a trigger latch. We still need to make sure we receive BOTH optical fiber helicity signals and synchronize scalers with them. Also, there may be a problem reading in the nA BPMs since their electronics lives on the space frame. Overall optimism!

Short Reports

Mehmet Bektasoglu showed preliminary results from a comparison between GSIM and actual E1 data for inclusive electron scattering. A normalization error (meanwhile corrected) prevented direct comparison, but shapes look simular. (Note: Stepan Stepanyan reported similar work at the N* meeting the next day, with good agreement). I argued that this work is important to be ready for dilution factor measurements (and for planning purposes).

all

Next meeting: Tentative plan right now is to have the next EG1 meeting on Thursday, June 4 (day before the CLAS collaboration meeting). Send in your availability and any known conflicts.