Spectrometer Optics

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Procedure without Sieve-slit

  • Time estimate: 4 hours
* Take a run at the following kinematics without the sieve-slit collimator on the multi-foil carbon target.
* 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, 6 mSr acceptance, and 9% 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 300k events at 20 μA
3.8 1.002 33.0 1.23 2.214 316 16

Procedure with Sieve-slit

  • Time estimate: 1-2 hours
* Trained personnel will be required to install the 1-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 25 out of 63 sieve holes have events (~ 0.265 mSr acceptance), and 9% delta acceptance.
* Note: if the right HRS minimum angle is 35 degrees instead of 33 degrees, then the rate will be ~ 50 Hz instead.
Ebeam [GeV] P0 [GeV/c] θe [deg] Q2 [GeV2] W [GeV] Rate [Hz] at 20 μA minutes for 90k events at 20 μA
3.8 1.002 33.0 1.23 2.214 17 90

Delta Scan with Hydrogen Elastic

  • Time estimate: 2-3 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
3.8 2.39025 33.0 -4 6 30
3.8 2.34429 33.0 -2 6 30
3.8 2.29832 33.0 0 6 30
3.8 2.25235 33.0 +2 6 30
3.8 2.20639 33.0 +4 6 30

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) e' (GeV) θe (deg) Q2 (GeV2) Rate [Hz] at 20 μA minutes for 20.6k events at 20 μA
3.8 2.29832 33.0 2.82 6 60
2.056 1.706 25.0
2.056 1.192 48.7