Spectrometer Optics First pass 48p8d
From Hall A Wiki
If you have questions call Vince Sulkosky or Kalyan Allada, Numbers are on white board
Integration with LHRS plan
|LHRS step||RHRS step||Approximate beam time||Goals||Status|
|L1 (sieve)||R1 (sieve)||14h||20 uA DIS with sieve slit on optics foils, single carbon and LH2||Completed|
|L2 (sieve)||3h||Delta Elastic on LH2, 1 uA||Completed|
|L3 (no sieve)||(no sieve)||3h||Elastic on carbon (Needs A. Camsonne as sieve operator)||In Progress|
|R2 (no sieve)||4-5h||Delta Elastic on LH2, 20 uA|
|R3 (no sieve)||1h||Elastic dummy|
|L1 (sieve)||R1 (sieve)||4h||20 uA DIS with sieve slit on 4 cm dummy (Needs A. Camsonne as sieve operator)|
|R4 (no sieve)||1h||DIS on dummy and optics||Dropped|
|L4 (sieve)||R5 (no sieve)||1h|| Tungsten wire
(Needs D. Mekins as wire operator)
Step R1: Procedure with Sieve-slit
- Time estimate: 12 hours
* 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 5 carbon foils, only 37 out of 155 sieve holes per foil have events (~ 0.4 mSr acceptance), and 8% delta acceptance. * Electron rates assume 2 aluminum foils, only 43 out of 155 sieve holes per foil have events (~ 0.47 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. * 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 20 μA||hours at 20 μA||Good Electrons|
|Carbon single foil||2.301||0.75||Off||48.74||1.18||1.617||2.2||1.3||10.3k events|
|15 cm LH2||2.301||0.75||2x2 mm2||48.74||1.18||1.617||20.0||1.3||96k events|
|4 cm Dummy||2.301||0.75||1x1 mm2||48.74||1.18||1.617||1.8||4||25k events|
Step R2: Delta Scan with Proton Elastic (without sieve slit)
- Time estimate: 3-4 hours
* Trained personnel will be required to remove the 1-inch tungsten sieve-slit collimator from the front face of the HRS. * Take runs 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. * Rate estimates only include elastic electrons and does not include rate from inelastic events or from the target endcaps. * The Q2 for these settings is 1.96 GeV2.
|Ebeam (GeV)||k' (GeV)||Raster||θe (deg)||ΔP (%)||Rate [Hz] at 20 μA||minutes at 20 μA||Good Electrons|
|2.301||1.304||2x2 mm2||48.74||-4||176||20||210k events|
|2.301||1.279||2x2 mm2||48.74||-2||176||20||210k events|
|2.301||1.254||2x2 mm2||48.74||0||176||50||500k events|
|2.301||1.229||2x2 mm2||48.74||+2||176||20||210k events|
|2.301||1.203||2x2 mm2||48.74||+4||176||20||210k events|
Step R3: Dummy Target Runs
- Go back to the ΔP = 0% elastic setting. Make sure the R-HRS P0 = 1.254 GeV.
- Move the target to "15 cm Dummy"
- Take R-HRS run with same setting as previous step. We need at least 100 k events.
- Take data with this setting for 1 hour
|Ebeam (GeV)||k' (GeV)||Raster||θe (deg)||ΔP (%)||Rate [Hz] at 20 μA||hours at 20 μA||Good Electrons|
|2.301||1.254||2x2 mm2||48.74||0||13.2||1||50k events|
Step R4: Procedure without Sieve-slit
- Time estimate: 1 hour
* 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. * Electron rates assume 5 carbon foils or 2 Al dummy foils, 5 mSr acceptance, and 8% delta acceptance. * A GMp expert will check the data quality.
|Target||Ebeam [GeV]||P0 [GeV/c]||Right Q1 Current [A]||θe [deg]||Q2 [GeV2]||W [GeV]||Rate [Hz] at 20 μA||minutes at 20 μA||Good Electrons|
|4 cm Dummy||2.301||0.75||153.36||48.74||1.18||1.617||37.4||22||50k events|
Step R5: Cross-wire Target Run
- Time estimate: 5 hours (includes access to install wire target and left HRS Sieve-slit)
* After the above runs are completed, ask for the target group (call Dave Meekins) to insert the cross-wire target (we are not allowed to do it). * Target expert will need to go to the Hall and manually move the target in position, so ask for controlled access before starting this step * At the same time have the Techs or A. Camsonne install the left HRS sieve-slit. The right HRS sieve-slit remains off. * Take a run with the cross-wire target with 2x2 mm2 rastered beam, and verify that the beam is centered on the cross-wire target using spot++. * If the beam in not centered, then ask MCC to move the beam until the rastered beam spot is centered on the wires. * Once beam is centered on the cross-wire target, have MCC turn off the raster. Make sure the spectrometers still have rates above cosmics by checking
the scaler rates. * Take a run with the with raster off for both LHRS and RHRS. * Electron rates assume 200 μm of tungsten. For LHRS, the rate is only for the central hole of the sieve slit (~ 0.023 mSr acceptance), and 8% delta acceptance. * A GMp expert will determine when enough good electron events have been collected.
|Spectrometer||Target||Sieve Slit||Raster||Ebeam [GeV]||P0 [GeV/c]||θe [deg]||Q2 [GeV2]||W [GeV]||Rate [Hz] at 1 μA||minutes at 1 μA||Good Electrons|
|Right HRS||200 μm tungsten wire||OUT||Off||2.301||0.75||48.74||1.18||1.617||3.28||30||5.9k events|
|Left HRS||200 μm tungsten wire||IN||Off||2.301||1.0||16.63||0.19||1.769||1.3||30||2.3k events|
- After finishing this step ask for Controlled access and call the target expert to move the wire-target out of the way. Also call Hall-A Tech on-call to remove the R-HRS sieve-slit.