Run1 - January 2015

Journal of shift summaries an important comments

Wednesday, Jan 14

• DAY
• SWING

Thursday, Jan 15

Friday, Jan 16

Saturday, Jan 17

Sunday, Jan 18

Monday, Jan 19

Experiment Goals and Plans

Tasks which have been studied or completed are shown below in bold face.

Prep Work (through Tuesday Jan 13)

1. Make a photocathode – SL5247-1 made about ~one week ago; QE low at low bias but ~1.8% at 130kV
2. Test IHA2D00 – the Aurora card was replaced to fix POT sampling and CAMAC wiring fixed for gain
3. Hi-Pot IP – 3D01 hi-potted, but still bad so moved to Dig#11 holding supply and 3D00 on Dig#12 monitors beam line only
4. CHL 2K cooldown – 1/13 successful cool down completed
5. Install laser – first beam test of Hall C laser with division by two rep rate
6. Test laser RF trigger – Riad is using Hall A laser as reference; appears to be 499/2^N
7. Verify beam line layout – completed
8. Build elegant deck – completed and stored at ~grames/elegant/MOTT/
9. Build qsUtility config file – completed, see below...

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

1. Restore beam to FC2 @ 6.3 MeV/c - 1/14 task was completed and summarized in link title
2. Mott test: DAQ FADC/TDC synchronization and event separation with 62MHz; results suggest beam=62MHz and trigger=31MHz OK
3. Electron bunchlength and transmission from 0-10 uA
4. Quad center BPMs for momentum measurement
5. Tested harp IHA2D00 and it works
6. Scale cryounit for p=5.487 MeV/c and minimize energy spread - 1/14 see entry for link initial setup
7. Tried bunchlength script - didn't coverge, but looks like with more time can work
8. Precisely measure beam momentum
9. Measure beam emittance
10. Measure energy spread
11. 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 contact people

Joe's cell

757-344-0188

How to reach the Mott logbook

Mott logbook is here

How to know who's on shift

How to be a shift worker

Beam Driver = Shift Leader

1. Control delivered beam, especially adjusting PITA with IHWP=IN/OUT
2. Make sure FSD (BCM, Target) protection is used
3. Monitor beam loss and vacuum levels
4. Save and document settings
5. Write shift summary in logbook

DAQ Driver

1. Configure/Start/Stop DAQ
2. Monitor event rates and maintain dead time <5%
3. Coordinate run start/stop
4. COPY run information into standard excel sheet

Analysis Driver

1. Decode, analyze and inspect runs
2. COPY run information into standard excel sheet
3. Determine number of events needed for IHWP=IN and OUT

How to measure emittance

Beam Setup

1. We measure the beam emittance and Twiss at entrance of MQJ0L02 by varying MQJ0L02 and observing response on harp IHA0L03
2. To simplify matters we turn off the intervening quadrupoles (MQJ0L02A = MQJ0L03A =MQJ0L03 = 0)
3. Obviously, make sure beam can transports from MQJ0L02 to IHA0L03 w/ those quads off (use BPM's and viewers)
4. 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

1. We use program named qsUtility to automatically to make the measurements and analyze the data
2. 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
3. qsUtility is documented here

qsUtility assumes v=c

1. 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

Note quads used for centering

1. MQJ0L02 = IPM0L02
2. MQJ0L03 = IPM0L03
3. MQD5D00 = IPM5D00
4. MQD5D01 = IPM5D01

Center quads

1. Mike Spata suggests standard dithering, as we do for solenoids
2. When complete update the BPM .SOF field and log result

Momentum measurement

1. Excite minimum number of correctors and record values
2. Set or measure BL using calculation on MDL0L02 control screen
3. Make note of BL for zeroing IPM0L02-IPM0L03 and IPM5D00-IPM5D01 with (intervening quads OFF, correctors OFF or recorded)
4. Calculate momentum from KE as p = sqrt [T*(2m+T)], so T = 5.0 MeV => p 5.487 MeV/c
5. Calculate fraction KE spread as dT/T = (T+2m)/(T+m) * dp/p, so dT/T=1.09 * dp/p @ T=5.0

How to use Elegant files

Elegant files for 2D, 3D, 5D, 0L regions

1. locate /grames/elegant/MOTT/mott3/
2. set mott3.ele beamline to be either 0L, 2D, 3D, 5D
3. set mott3.ele emittance, Twiss and momentum spread

To run

1. Copy files to local area
2. Interactively: Start IEE from terminal and then load elegant file: /grames/elegant/MOTT/mott3/mott3.ele
3. Command: From terminal execute elegant mott3.ele