Run1 - January 2015

Shift Responsibilties

Schedule

Duties

Beam Driver

Beam setup: gun + laser + spin + beam to Mott
BCM & target motion FSDs enabled 
Vacuum levels reasonable
Magnet and RF setup saved
PITA adjusted for IHWP IN/OUT

DAQ Driver

Start/Stop DAQ entering correct run information
Monitor event rates and maintain dead time <5%
Coordinate run start/stop with Beam and Analysis Drivers

Analysis Driver

Runs decoded, analyzed and promptly inspected
Run # and information logged onto run sheets
Elastic events counted for IHWP=IN/OUT

Experiment Goals and Plans

Prep Work (through Tuesday Jan 13)

1. Make a photocathode – SL5247-1 made
2. Test IHA2D00 – wires & stroke good, but data file odd vs. others
3. Hi-Pot IP – FE’r potted, but high again, vac readback not good
4. CHL 2K cooldown – maybe early, Monday Jan 12th
5. Install laser – Tue or Wed
6. Test laser RF trigger – after laser installed (1V, 10ns @ RF)
7. Verify beam line layout –documented below
8. Build elegant deck – working
9. Build qsUtility config file –documented below

Injector Setup and Mott Checkout (Wed Jan 14 - Fri Jan 16)

1. Restore beam to FC2 @ 6.3 MeV/c
2. Mott test: DAQ FADC/TDC synchronization
3. Mott test: event separation and transmission at 62MHz acceptable
4. Quad center BPMs for momentum measurement
5. Test harp IHA2D00 if ready for energy spread measurement
6. Scale cryounit for p=5.487 MeV/c and minimize energy spread
7. Precisely measure beam momentum
8. Measure beam emittance
9. Measure energy spread
10. Calibrate BCM to FC2

Mott Setup and Systematics Testing (Sat Jan 17)

1. Setup good orbit to Mott
2. Set PMT HV
3. Set PMT energy thresholds
4. Set polarization vertically
5. Calibrate PITA vs IHWP IN/OUT
6. Finalize orbit w/ instrumental asymmetry, TOF and spectra
7. Adjust target offsets per vertical instrumental asymmetry
8. Measure dump rate fraction to determine run times
9. Measure dead-time vs. rate
10. Measure asymmetry vs. beam current
11. Measure asymmetry vs. time (stability)
12. Measure asymmetry vs. spot size
13. Measure asymmetry vs. energy spread

Target Foil Extrapolation (Sat Jan 17 - Mon Jan 19)

14 foils to study + 1 thru hole

spectra – with typical low ~2 MeV energy threshold
statistics – possibly higher ~3 MeV threshold to reduce dump events

Deadtime

Semi-int mode we use w/ FADC/TDC/scalar is ~5% @ 1500 Hz

Inelastic fraction

Worst case ~200 Hz/det  (best case ~25 Hz/det) 
Energy threshold will be defined to set this value
Time veto is tricky and too risky at 62 MHz

Assuming I=5uA, R<1500Hz, 200Hz/det background

28 hours * 1.2 / 8 = 4-5 shifts
dP/P sets N_elastic (using 1σ analysis cut of all 4 det)
Measurement of of inelastic (dump) events figures into run time

Procedures

How to measure emittance

Beam Setup

We measure the beam emittance and Twiss at entrance of MQJ0L02 by varying MQJ0L02 and observing response on harp IHA0L03
To simplify matters we turn off the intervening quadrupoles (MQJ0L02A = MQJ0L03A =MQJ0L03 = 0)
Obviously, make sure beam can transports from MQJ0L02 to IHA0L03 w/ those quads off (use BPM's and viewers)
The configuration changes MQJ0L02 B for 21 K1 values (-3.0, -3.2, … , -5.8, -6.0); this takes ~45 minutes, so a smaller data set could be used too

qsUtility

We use program named qsUtility to automatically to make the measurements and analyze the data
The measurement configuration file is here and can also be used as a template /cs/prohome/apps/q/qsUtility/pro/fileio/config/IHA0L03_jmg1.xml
qsUtility is documented here

qsUtility assumes v=c

One must scale the Energy [MeV] entry box as the tool uses this formula B'L [G] = K1[1/m^2] * L[m] * E[MeV] * 10/0.2998

How to measure momentum

Before using absolute BPM's perform centering procedure to adjacent quadrupoles

MQJ0L02 = IPM0L02
MQJ0L03 = IPM0L03
MQD5D00 = IPM5D00
MQD5D01 = IPM5D01
Mike Spata suggests standard dithering, as we do for solenoids
When complete update the BPM .SOF field and log result

Beam steering

Earth’s field is likely too strong to turn zero intervening correctors
Excite minimum number of correctors and record values
p = sqrt [T*(2m+T)] so T = 5.0 MeV =>  p 5.487 MeV/c
Check me: dT/T = (T+2m)/(T+m) * dp/p so dT/T=1.09 * dp/p @ T=5.0
Use the BL calculation on the control screen of MDL0L02