Difference between revisions of "Spectrometer Optics First pass 48p8d"

Revision as of 18:19, 23 February 2016

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. 

Step R2: Delta Scan with Proton Elastic (without sieve slit)

• Time estimate: 3 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.

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

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.

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).
* At the same time have the Techs or A. Camsonne install the left HRS sieve-slit.  The right HRS sieve-slit remains off.
* 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  
* Take a run with the cross-wire target with 2x2 mm2 rastered beam, and verify that the beam is horizontally centered on the wire target using spot++.
* If the beam in not centered, then ask MCC to move the beam until the rastered beam spot is centered horizontally.
* Once beam is centered on the 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 wire target with raster off.
* Electron rates assume 200 μm of tungsten, 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.

• 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.