Page History

 Communications

- Running since this morning 9AM with 2 spills, 3 spills available since 2.30PM. Currently taking tagged photons from 1GeV e beam
- 60K evts of 2.5GeV e taken for reference after shutdown
- Sh became inefficient and empty events were triggering the si tagger; S3 is now isntalled as a veto over the S2 light-guide (Nicola M)
- verified feasibility of 500MeV beam: rate is ok but beam is larger, will have to verify if S3 veto is ok and final tagging rate
  running smoothly since yesterday, 2 CU positions completed at 2.5Gev, both tagged and full bream photons, 2 position completed at 1GeV tagged, currently running tagged photons at 0.5GeV with CU at 0 angle; 3rd position tagged photon by tonight, 3rd position full-brem at 2.5GeV for the owl shift
- dump position: last night understood that 1GeV beam and 0.5GeV  beam have larger divergence and some photons hit the dump; larger statistics for the 1Gev tagged photons was requested to compensate; the same was observed today with straight e in the CU, displaying a clear cut in the beam spot. The effect is larger with photons as the brem - induced divergence (scales as m/p)  adds to the larger e beam divergenve. We removed the last pb brick wall from the dump, increasing the dump-beam distance to 11cm still keeping the unradiated beam within 23cm Pb (>6 moliere radii) when the magnet is ON
- discussion for definition of 4th CU position: current agreement is to simulate albedo gammas by shooting gammas at 145 degrees in the tower 3 CAL; the impact point would be half way in the CAL, as having gammas too close to the TKR would give too poor an energy resolution, while shooting from the bottom of the CAL side would result in very few events making their way to the TKR. Philippe is concerned that we also get some tagged gammas in such configuration to cross-check the energy as the CU energy measurement would be very poor; suggestions were made to evaluate the possibility of placing the ACD tile currently on top on the side of tower 3, to be able to run background rejection cuts similar to the LAT ones. Luca to evaluate time to move ACD tile and contact Bill and Steve to check if this position is ok, or they feel other configurations should come before.

 Online&DAQ Report

 OfflineReport

- Philippe presented plots from test sync runs with e which show how events with no energy in the cal point to the dump as measured by the 1st arm of the tagger
- Berrie showed plots from full-brem runs which have less conversion in the top and thick layers wrt to the MC

 Program

- agreed program here
- reduce shifters for owl to 2 for the next 3 nights as running full-brem is simple 

 Notes 

 Communications

- Running since this morning 9AM with 2 spills, 3 spills available since 2.30PM. Currently taking tagged photons from 1GeV e beam
- 60K evts of 2.5GeV e taken for reference after shutdown
- Sh became inefficient and empty events were triggering the si tagger; S3 is now isntalled as a veto over the S2 light-guide (Nicola M)
- verified feasibility of 500MeV beam: rate is ok but beam is larger, will have to verify if S3 veto is ok and final tagging rate
- CU position 2 defined as x=200, Y=0, Z=-48, angle = 30
 

 Online&DAQ Report

DAQ synchronization lost once, tagged photon run stopped and restarted with no event loss

 OfflineReport

- Philippe reported on analysis of tagger calibration runs, tagger energy resolution same as what measured and presented by Nicola yesterday; one of the analyzed runs appear as 1.12GeV e in the rcReport, while the actual energy was 1.125, Luca B believe there is an issue with trunctation which the database people should address at SLAC (Eduardo to check)
- Eric working on the setting of the VETO threshold for the ACD 

 Online&DAQ Report

 OfflineReport

 Program

- agreed program here
- reduce shifters for owl to 2 for the next 3 nights as running full-brem is simple 

 Notes