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User name E.Chudakov
Log entry time 18:13:44 on January 13, 2009
Entry number 255865
keyword=Moller results, spin danceMoller results on Jan 13 11:20-16:30
Tuning took 1h 10m.- There was no energy lock..
- The raster was ON.
- For the beam energy current - see the chart attached.
| # | Wien angle | beam | runs | target | Ptarget% | Pbeam% |
|---|---|---|---|---|---|---|
| 1 | 30° | 0.58 µA | 13055-13058 | 5 | 7.97 | -81.7±0.3±2.0 |
| 2 | 30° | 0.80 µA | 13059-13060 | 5 | 7.97 | -81.1±0.3±2.0 |
| 3 | 50° | 0.80 µA | 13061-13064 | 5 | 7.97 | -90.8±0.3±2.0 |
| 4 | 70° | 0.80 µA | 13065-13068 | 5 | 7.97 | -88.4±0.3±2.0 |
| 5 | -30° | 0.80 µA | 13070-13073 | 5 | 7.97 | -9.4±0.3±2.0 |
| 6 | 54° | 0.80 µA | 13074-13077 | 5 | 7.97 | -91.0±0.3±2.0 |
| 7 | 54° | 0.80 µA | 13079-13082 | 4 | 7.44 | -90.5±0.2±2.0 |
| 8 | 54° | 0.55 µA | 13083-13086 | 3 | 7.62 | -88.0±0.2±2.0 |
| 9 | 54° | 0.55 µA | 13087-13090 | 2 | 8.21 | -90.8±0.2±2.0 |
| 10 | 30° | 0.80 µA | 13091-13094 | 5 | 7.97 | -82.3±0.2±2.0 |
| average 6,7,9 | 54° | average the targets | -90.8±0.1±2.0 | |||
| 2,3,4,5 | dance | 0.80 µA | maximum at 54±1.° | 5 | 7.97 | -91.0±0.2±2.0 |
| best | 30° | scaled to all targets | -82.1±0.3±2.0 | |||
Spin Dance Results
In Hall A, the spin is parallel at a Wien angle of 54±1.°. From this, assuming symmetric linacs, we derive the energy per linac of 583.35 MeV, which gives the Hall A energy of 5.899 GeV. This is about 7 MeV higher than the measured energy. The difference might be caused by a linacs' disbalance. The spin would be parallel at 15.5° in Hall B (5 passes) and at 23° in Hall C (4 passes) . The sum of squares of the longitudinal polarizations in all 3 halls would be maximized at about 30°.
A large chi2 of the spin dance fit (20/NDF) is likely caused by an energy instability,
which affects the measurements at large spin angles (far from 54°).
Figure 1
Figure 2
