Spectrometer Optics 1pass

From Hall A Wiki
Jump to: navigation, search

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
2.0 0.75 43.7 0.83 1.551 9.2 190

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 1.3106 43.7 -4
2.0 1.2854 43.7 -2
2.0 1.2602 43.7 0
2.0 1.2350 43.7 +2
2.0 1.2098 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
2.0 1.26022 43.7 1.40