Procedure with Sieve-slit
* 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 |
3.056 |
19 |
2.4 |
2533 |
16 |
105 |
| 7.3 |
2.019 |
19 |
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 100k events at 20 μA |
| 7.3 |
2.918 |
22.8 |
2.33 |
2403 |
20 |
85 |
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 200k events at 20 μA |
| 7.3 |
2.918 |
22.8 |
2.33 |
2403 |
230 |
15 |
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 |
