Difference between revisions of "Fall 2016 LHRS optic plans"
From Hall A Wiki
(→Step L4: Proton Elastic Kinematics) |
(→Step L4: Proton Elastic Kinematics) |
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* Take one hour on the optics target. | * Take one hour on the optics target. | ||
* <b>A GMp expert will check the data quality.</b> | * <b>A GMp expert will check the data quality.</b> | ||
| − | + | * <b>1st Pass (E<SUB>beam</SUB> = 2.2 GeV)</b> Time estimate: 19 days @ 60 μA | |
| − | + | ||
| − | + | ||
| − | * <b> | + | |
<table border="1" style="width:80%"> | <table border="1" style="width:80%"> | ||
<tr> | <tr> | ||
| Line 180: | Line 177: | ||
<td>θ<SUB>e</SUB> [deg]</td> | <td>θ<SUB>e</SUB> [deg]</td> | ||
<td>Q<SUP>2</SUP> [GeV<SUP>2</SUP>]</td> | <td>Q<SUP>2</SUP> [GeV<SUP>2</SUP>]</td> | ||
| − | <td> Electron Rate [Hz] at | + | <td> Electron Rate [Hz] at 60 μA</td> |
| − | <td><b>PAC days</b> at | + | <td><b>PAC days</b> at 60 μA</td> |
</tr> | </tr> | ||
<tr> | <tr> | ||
<td>15 cm LH2</td> | <td>15 cm LH2</td> | ||
| − | <td> | + | <td>3 x 3 mm<sup>2</sup></td> |
| − | <td> | + | <td>2.217</td> |
| − | <td> | + | <td>1.366</td> |
| − | <td> | + | <td>42.0</td> |
| − | <td> | + | <td>1.57</td> |
| − | <td> | + | <td>1700</td> |
<td>19 (for 29k events)</td> | <td>19 (for 29k events)</td> | ||
</tr> | </tr> | ||
Revision as of 18:56, 8 October 2016
Contents
Step L1: Procedure with Sieve-slit
- Time estimate: 1 hour
* Trained personnel will be required to install the 1-inch tungsten sieve-slit collimator onto the front face of the HRS. * If you need to increase the spectrometer momentum setting, make sure you cycle Q2 and Q3 as per the cycling procedure. * Take sieve-slit runs with the multi-foil carbon target (optics) for the inelastic kinematics in the table. * Electron rates assume 9 carbon foils, only 37 out of 155 sieve holes per foil have events (~ 0.41 mSr acceptance), and 8% delta acceptance. * Electron rates assume 15 cm LH2 target, only 45 out of 155 sieve holes have events (~ 0.49 mSr acceptance), and 8% delta acceptance. * Adjust the prescale factors to keep the DAQ deadtime below 10%. * Before moving on to the next target, a GMp expert will determine online how many good electron events have been collected.
| Target | Ebeam [GeV] | P0 [GeV/c] | Raster | θe [deg] | Q2 [GeV2] | W [GeV] | Rate [Hz] at 60 μA | minutes at 60 μA | Good Electrons |
| Optics | 2.217 | 1.0 | Off | 17.5 | 0.20 | 1.72 | 540 | 32 | 1M events |
| 15 cm LH2 | 2.217 | 1.0 | 3x3 mm2 | 17.5 | 0.20 | 1.72 | 4600 | 10.0 | 2.7M events |
Step L2: Delta Scan with Proton Elastic (with sieve slit)
- Time estimate: 1.5 hours
* Keep the 1-inch tungsten sieve-slit collimator on the front face of the left HRS. * Take runs with the 15 cm liquid hydrogen target for the elastic kinematics in the table. * Wait until the left 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. * Rate estimates only include elastic electrons and does not include rate from inelastic events or from the target endcaps. * Adjust the prescale factors to keep the DAQ deadtime below 10%. * The Q2 for these settings is 0.41 GeV2.
| Ebeam (GeV) | k' (GeV) | Raster | θe (deg) | ΔP (%) | Rate [Hz] at 10 μA | minutes at 10 μA | Good Electrons |
| 2.217 | 2.078 | 3x3 mm2 | 17.5 | -4 | 10,000 (2500 Hz with ps = 4) | 10 | 1M events |
| 2.217 | 2.038 | 3x3 mm2 | 17.5 | -2 | 10,000 (2500 Hz with ps = 4) | 10 | 1M events |
| 2.217 | 1.998 | 3x3 mm2 | 17.5 | 0 | 10,000 (2500 Hz with ps = 4) | 10 | 1M events |
| 2.217 | 1.958 | 3x3 mm2 | 17.5 | +2 | 10,000 (2500 Hz with ps = 4) | 10 | 1M events |
| 2.217 | 1.918 | 3x3 mm2 | 17.5 | +4 | 10,000 (2500 Hz with ps = 4) | 10 | 1M events |
Step L3: Dummy Target Runs
- Go back to the ΔP = 0% elastic setting. Make sure the L-HRS P0 = 1.998 GeV.
- Move the target to "15 cm Dummy"
- Take L-HRS run with same setting as previous step.
- Take data with this setting for 10 minutes
| Ebeam (GeV) | k' (GeV) | Raster | θe (deg) | ΔP (%) | Rate [Hz] at 10 μA | minutes at 10 μA | Good Electrons |
| 2.217 | 1.998 | 3x3 mm2 | 17.5 | 0 | 460 | 10 | 270k events |
Step L4: Proton Elastic Kinematics
- Time estimate: 1 hour
* Trained personnel will be required to remove the 1-inch tungsten sieve-slit collimator from the front face of the HRS. * Hall A Technical staff will need to move the left HRS from 17.5 degrees to 42 degrees. * If you need to increase the spectrometer momentum setting, make sure you cycle Q2 and Q3 as per the cycling procedure. * Elastic electron rates assume 15 μA on 15 cm LH2 target, 5 mSr acceptance. * Use the following prescale factors: ps1=1, ps2=1, ps3=1, ps8=100. All other triggers should have zero prescale factor. * The 15 cm dummy runs need to be taken at the elastic setting. So keep the momentum as is for this run. * For the optics pointing run, decrease the spectrometer momentum to 0.85 GeV/c. The right dipole will need about 1.5 hours to settle. * Take one hour on the optics target. * A GMp expert will check the data quality.
- 1st Pass (Ebeam = 2.2 GeV) Time estimate: 19 days @ 60 μA
| Target | Raster | Ebeam [GeV] | P0 [GeV/c] | θe [deg] | Q2 [GeV2] | Electron Rate [Hz] at 60 μA | PAC days at 60 μA |
| 15 cm LH2 | 3 x 3 mm2 | 2.217 | 1.366 | 42.0 | 1.57 | 1700 | 19 (for 29k events) |
| Optics | Off | 8.517 | 0.85 | 48.75 | 4.93 | 6.9 | 1 hour (for 24k events) |
| 15 cm Dummy | 2 x 2 mm2 | 8.517 | 2.081 | 48.75 | 12.08 | ---- | 1 hour |
