Log entry time 07:54:17 on June 28, 2010

Entry number 328891

Followups:

• 328894 06/28/10 08:17 Markowitz VDC current readout not working

Swing Shift Summary: June 26, 2010

Shift Crew

• Pete Markowitz
• Aidan Kelleher
• Eli Piazetsky

Event Summary

• 00:00 Shift started with no beam, Bogdan working on RHRS detectors. MCC thought to be several hours from beam.
• 00:25 Markowitz, Kelleher go downstairs to work on wiring up S2m. Vince comes in to fix clock for scalers. 00:09 Out of hall, MCC ready to deliver beam.
• 01:09 First beam in hall. MCC tuning. Put in Tantalum target but see no rate(?) T1 and T2 are about 10% greater than cosmic with 0.5uA. Head scratchings, magnet checks, etc.
• 02:47 Move to thick carbon target. See T2~3 KHz with 1 uA.
• 03:00 Access to fix TDC spectra. Bogdan reverses earlier cable change and TDC spectra are no longer empty.
• Q1 current oscillations return. Tried trick from last shift (turn off regulation, set current to proper value, turn on regulation) but that no longer works. Since we are not doing optics, small oscillations may be tolerable now but day shift should ask a tech to look at this.
• 03:49 Septum back on, running thick carbon and spectra no longer empty.
• 03:59 Move to Tantalum. Still no rate. Maybe the Ta target is gone? Rates stay about cosmic rates (T1~1KHz, T2~140 Hz, T5=T1~1KHz).
• 04:21 Move to Pb-D1. Healthy rate (T1~16 KHz, T2~8.9KHz) with 1 uA.
• 04:45 Septum off for access. Bogdan will put gas cerenkov into T5 trigger. T1 is S2m, T2 is S0, and T5 is T1 currently. Sergei has a nice plot showing positrons in the lead glass detector.
• 05:55 Out of hall, septum back on. T5 should now have the gas cerenkov in coincidence with T2, the S0 trigger (T1 is out of the T5 trigger now). Ask for 1 uA on the Pb-D1 target.
• 06:03 Ask MCC to take away beam while we analyze run 1282, to keep radiation in hall low. Run 1282 should have T5 as positron rate.
• 06:10 Beam off rates are 0.5 Hz for T5, 400 Hz for T2. With 1 uA on the Pb-D1, we saw T2~14KHz and T5~532Hz. I.e., after subtracting cosmics, the pion rates are about 7.3KHz and the positron rates about about 532 Hz, or a ratio of ~24:1 if this was a good trigger.
• 06:20 Move the thick carbon target to check ratio of rates there. Run 1283, 1uA on the thick carbon. Rates are 2.3KHz for T2 (with ~400 Hz being cosmics), 14Hz for T5 giving a ratio of 140:1.
• 06:35 HV were changed. Move back to Pb-D1. Run 1284 is with the new gas cerenkov HV.
• 06:40 Move to thick carbon and start run 1285.
• 07:07 Change gas cerenkov HV again. Move target to PbD1, start run 1286
• 07:15 More HV changes. Start moving to 12C thick, but reconsider and stay on Pb-D1. Start run 1287.
• 07:30 More HV changes. Run 1288.
• 07:40 Final HV changes. Run 1289. At end, ask for hall to go to controlled access for day shift.

Issues that need sumpin'

• End of run statements give essentially zero for BCM average current values. Maybe something is not calibrated? Runs have also been very short too.
• Q1 current/field oscillates. Swing shift had thought this was fixed but apparently not.
• Tantalum target foil is probably gone.
• Spot is not working.