Fall 2016 LHRS optic plans

Step L1: Procedure with Sieve-slit

• Time estimate: 6 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 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.
* 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 60 μA	minutes at 60 μA	Good Electrons
Optics	2.217	1.0	Off	17.5	0.20	1.72	540	32	1M events
15 cm LH2	2.217	1.0	3x3 mm2	17.5	0.20	1.72	4600	10.0	2.7M events

Step L2: 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 1.86 GeV2.

Ebeam (GeV)	k' (GeV)	Raster	θe (deg)	ΔP (%)	Rate [Hz] at 60 μA	minutes at 60 μA	Good Electrons
2.217	1.277	3x3 mm2	17.5	-4	650	10	390k events
2.217	1.253	3x3 mm2	17.5	-2	650	10	390k events
2.217	1.228	3x3 mm2	17.5	0	650	20	780k events
2.217	1.204	3x3 mm2	17.5	+2	650	10	390k events
2.217	1.179	3x3 mm2	17.5	+4	650	10	390k events

Step L3: Dummy Target Runs

• Go back to the ΔP = 0% elastic setting. Make sure the L-HRS P0 = 1.228 GeV.
• Move the target to "15 cm Dummy"
• Take R-HRS run with same setting as previous step.
• Take data with this setting for 1 hour

Ebeam (GeV)	k' (GeV)	Raster	θe (deg)	ΔP (%)	Rate [Hz] at 40 μA	hours at 40 μA	Good Electrons
2.217	1.228	3x3 mm2	17.5	0	19.5	1	70k events

Step L4: 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 9 carbon foils or 1 single carbon foil, 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 60 μA	minutes at 60 μA	Good Electrons
Optics	2.217	1.0	173.808	17.5	1.51	1.287	250	15	220k events
Single Carbon	2.217	1.0	173.808	17.5	1.51	1.287	56	15	50k events