From Hall A Wiki
Revision as of 12:57, 18 November 2008 by Jiang (→NEW as of 11/18/08: Production Run Plan, Xiaodong Jiang)
This is the run plan for transversity experiment
Pre-beam checklists txt file updated on 10/21/2008
Hall A floor plan layout for Transversity/d2n
NEW as of 11/18/08: Production Run Plan, Xiaodong Jiang
Production, basic principles.
Production, target transversely polarized, in-plane left/right and verticle up/down. And, reference cell runs H2 gas 110 psi, when plarized He3 cell need a recovery time.
Keep doing production runs as much as possible, limit controlled access whenever possible. Keep all HV and low-voltage settings and magnet settings stable. All changes need run coordinator's explicit approval.
BigBite gas Cherenkov, left arm RICH detector, and Compton related activities in the Hall should only happen during a planned down time.
Basic principles guiding the decisions for production run, changes include: i. HRS_L polarity change, equally split time between HRS_positive and HRS_negative polarity Set HRS_left to 2.35 GeV/c.
ii. Beam half-wave plate IN/OUT changes, equally split. Need to coordinate with Hall B.
iii. Moller measurement every week (or after major injector change). Prefer two back-to-back Moller measurements before/after the beam half wave plate changes.
iv. Whenever the polarized target is down or need a recovery, run reference cell H2 gas 110 psi, With the same configuration (and keep the same prescale factors) .
The "true target-spin-flip" should be turned off to prevent target polarization loss. However, the "Real-fake" target spin flip signal should be ON for false asymmetry measurements.
A run on BeO target (same as carbon multifoil), 10 minutes, should be taken once every two days, to verify tracking reconstruction (take all T5, 100-200 Hz T3 and T1 and T6, dead time doesn't matter). v. Special runs on continous commissioning of BB Cherenkov, left-arm RICH, etc can be taken once (or maybe twice) daily, 10-15 minutes each. This activity should be well coordinated, prefer to be during the polarized target's down time. Run coordinator's explicit approval is needed.
Day-to-day run plan, 11/18/2008, 11:00am,
1. Reestablish beam position after target movement failar.
2. Start polarized He3-cell production run, 12 uA beam, Target spin orientation: Transvers-in-plan, same as during the last week.
3. Around 6:00pm or so, when target experts recovered: Rotate target spin to: vertical up-down. Target laser need to be re-configured, target polarization need to be measured before and after.
During this time, we can run reference cell with H2 gas 110 psi, with the same configuration as in production (and keep the same prescale factors) . The "true target-spin-flip" should be turned off to prevent target polarization loss. However, the "Real-fake" target spin flip signal should be ON for false asymmetry measurements.
The nominal beam position on the reference cell need to be checked (and established), the procedure should be:
i. Move target to reference cell, run a lower current, 1uA or 2 uA. With the regular BPM position, regular raster setting (3*4 by MCC), record the scaler rates.
ii. Change raster size, to 5*5, and 6*6 (MCC setting) record scaler rates. If the scaler rates do not shot up dramatically, then it is fine, we are not hitting the cell walls.
Otherwise, we need to move the beam around by the same offsets in BPMA and BPMB until a spot can be found where the rates are stable for different raster settings.
Record the final BPM positions for bothe A and B. This is our reference cell production spot setting.
4. After the target spin rotation is completed, return back to production, 12 uA beam. Same running condition, prescale factors as during the day.
5. Keep production, watch out for target spin-flip and monitor target polarization.