Difference between revisions of "Spectrometer Optics 1pass"
From Hall A Wiki
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Revision as of 17:19, 17 March 2015
Contents
Procedure without Sieve-slit
- Time estimate: 4 hours
* Take a run at the following kinematics without the sieve-slit collimator. * Start with initial right HRS spectrometer tune with the SOS quad in place of right Q1. * If you need to increase the spectrometer momentum setting, make sure you cycle Q2 and Q3 as per the cycling procedure. * Rates assume 5 carbon foils, 5 mSr acceptance, and 8% delta acceptance. * A GMp expert will check the data quality and decide, if the right HRS tune needs to be adjusted to change the size of the acceptance. * This process will be repeated until the spectrometer tune is satisfactory.
| Ebeam [GeV] | P0 [GeV/c] | θe [deg] | Q2 [GeV2] | W [GeV] | Rate [Hz] at 20 μA | minutes for 260k events at 20 μA |
| 2.0 | 0.75 | 43.7 | 0.83 | 1.551 | 173 | 25 |
Procedure with Sieve-slit
- Time estimate: 3 hours
* Trained personnel will be required to install the 1-inch tungsten sieve-slit collimator onto the front face of the HRS. * Take a sieve slit run with the multi-foil carbon target for the inelastic kinematics in the table. * If you need to increase the spectrometer momentum setting, make sure you cycle Q2 and Q3 as per the cycling procedure. * Repeat the above with the beam position shifted so that you see a vertical shift by one row. * Rates assume 5 carbon foils, only 25 out of 63 sieve holes have events (~ 0.265 mSr acceptance), and 8% delta acceptance.
| Ebeam [GeV] | P0 [GeV/c] | θe [deg] | Q2 [GeV2] | W [GeV] | Rate [Hz] at 20 μA | minutes for 100k events at 20 μA |
| 1.9 | 0.75 | 43.7 | 0.79 | 1.500 | 10 | 160 |
Delta Scan with Proton Elastic
- Time estimate: 1-2 hours
* Trained personnel will be required to remove the 1-inch lead sieve-slit collimator onto the front face of the HRS. * Take a run with the 15 cm liquid hydrogen target for the elastic kinematics in the table. * There will be a time lapse between settings until the right dipole reaches the desired momentum and is stable. * If you need to increase the spectrometer momentum setting, make sure you cycle Q2 and Q3 as per the cycling procedure.
| Ebeam (GeV) | k' (GeV) | θe (deg) | ΔP (%) | Rate [Hz] at 20 μA | minutes for 10k events at 20 μA |
| 2.0 | 1.2659 | 43.7 | -4 | ||
| 1.9 | 1.2415 | 43.7 | -2 | ||
| 1.9 | 1.2172 | 43.7 | 0 | ||
| 1.9 | 1.1928 | 43.7 | +2 | ||
| 1.9 | 1.1685 | 43.7 | +4 |
Elastic from Hydrogen
- Time estimate: 1-2 hours
* If you need to increase the spectrometer momentum setting, make sure you cycle Q2 and Q3 as per the cycling procedure. * Elastic electron-proton measurement. Assuming a 15 cm LH2 target, a spectrometer acceptance of 5 msr and elastic from Eric's rate program
to compute the cross-section.
| Ebeam (GeV) | k' (GeV) | θe (deg) | Q2 (GeV2) | Rate [Hz] at 20 μA | minutes for 40k events at 20 μA |
| 1.9 | 1.2172 | 43.7 | 1.28 |
