Difference between revisions of "Spectrometer Optics"
From Hall A Wiki
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<td>7.3</td> | <td>7.3</td> | ||
| − | <td>3. | + | <td>3.056</td> |
<td>19.0</td> | <td>19.0</td> | ||
| − | <td>2. | + | <td>2.4</td> |
| − | <td> | + | <td>2533</td> |
| − | <td> | + | <td>670</td> |
| − | <td> | + | <td>10</td> |
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Revision as of 16:44, 16 October 2014
Procedure with Sieve-slit
- Time estimate: 1-2 hours
* A Hall A Tech may be required to install the 2-inch lead 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 9 out of 25 sieve holes have events (~ 0.146 mSr acceptance), and 9% 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 |
| 7.3 | 3.200 | 19.0 | 2.5 | 2455 | 15 | 110 |
| 7.3 | 2.019 | 19.0 | 1.6 | 3030 | 24 | 70 |
Alternative rates with 1-inch tungsten sieve slit: * Assumes that 49 out of the 63 holes are seen (~ 0.52 mSr acceptance); however, the acceptance is reduced by 85%,
since not all foils will see all holes. * Rates assume 5 carbon foils and 9% delta acceptance.
| Ebeam [GeV] | P0 [GeV/c] | θe [deg] | Q2 [GeV2] | W [GeV] | Rate [Hz] at 20 μA | minutes for 200k events at 20 μA |
| 7.3 | 3.056 | 19.0 | 2.4 | 2533 | 58 | 58 |
Procedure without Sieve-slit
- Next take a run at the following kinematics without the sieve-slit collimator.
- 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, 6 mSr acceptance, and 9% delta acceptance.
| Ebeam [GeV] | P0 [GeV/c] | θe [deg] | Q2 [GeV2] | W [GeV] | Rate [Hz] at 20 μA | minutes for 400k events at 20 μA |
| 7.3 | 3.056 | 19.0 | 2.4 | 2533 | 670 | 10 |
Elastic from Hydrogen
Elastic electron-proton measurement. Assuming a 15 cm LH2 target, a spectrometer acceptance of 6 msr and elastic from Eric's rate program to compute the cross-section. Taking data at 7.3 GeV with the given momentum restrictions is time consuming.
(Table borrowed from DVCS3 wiki page)
| Ebeam (GeV) | k' (GeV) | θe (deg) | Q2 (GeV2) | Rate [Hz] at 20 μA | minutes for 5.4k events at 20 μA |
| 7.3 | 3.2 | 33.4 | 7.7 | 1.5 | 60 |
| 5.5 | 3.2 | 28.7 | 4.3 | 15 | 6 |
