Difference between revisions of "Fall 2016 LHRS optic plans"

Revision as of 19:51, 15 October 2016

Step L1: Procedure with Sieve-slit

• Time estimate: 1 hour

* 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 9 carbon foils, only 37 out of 155 sieve holes per foil have events (~ 0.41 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.
* Adjust the prescale factors to keep the DAQ deadtime below 10%.
* Before moving on to the next target, a GMp expert will determine online how many good electron events have been collected. 

Step L2: Delta Scan with Proton Elastic (with sieve slit)

• Time estimate: 1.5 hours

* Keep the 1-inch tungsten sieve-slit collimator on the front face of the left HRS.
* Take runs with the 15 cm liquid hydrogen target for the elastic kinematics in the table.
* Wait until the left 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.
* Adjust the prescale factors to keep the DAQ deadtime below 10%.
* The Q2 for these settings is 0.41 GeV2.

Step L3: Dummy Target Runs

• Go back to the ΔP = 0% elastic setting. Make sure the L-HRS P0 = 1.998 GeV.
• Move the target to "15 cm Dummy"
• Take L-HRS run with same setting as previous step.
• Take data with this setting for 10 minutes

Step L4: Proton Elastic Kinematics

• Time estimate: 1 hour

* Trained personnel will be required to remove the 1-inch tungsten sieve-slit collimator from the front face of the HRS.
* Hall A Technical staff will need to move the left HRS from 17.5 degrees to 42 degrees.
* If you need to increase the spectrometer momentum setting, make sure you cycle Q2 and Q3 as per the cycling procedure.
* Elastic electron rates assume 15 μA on 15 cm LH2 target, 5 mSr acceptance.
* Use the following prescale factors: ps1=1, ps2=1, ps3=1, ps8=100. All other triggers should have zero prescale factor.
* The 15 cm dummy and carbon pointing runs need to be taken at the elastic setting.  So keep the momentum as is. 
* A GMp expert will check the data quality.