- 1 The Hall A Compton
- 2 Shift Workers' Operation Guide
- 3 Information for Compton Experts
- 4 Compton Meetings
- 5 Current Compton Experts
- 6 Expert Information
- 7 Old Compton page (pre-Spring 2016)
The Hall A Compton
The Compton polarimeter is used to (non-invasively) monitor polarization of the incoming electron beam. It has three major components: an optics table with a laser that can lock to a Fabry-Perot cavity, an electron detector, and a photon detector to count scattered electrons and photons, respectively.
Last edit: LThorne 02:08, 24 February 2016 (UTC)
Shift Workers' Operation Guide
Start a Compton run every two hours.
The Compton DAQ is located in the back room in the Counting House. All commands are done from compton@compton.
If CODA is not already running:
- Kill CODA first, then start it up again:
$ kcoda $ startcoda
- A few new Terminal windows and a GUI pop up.
- Let "top" refer to the bar with named menu options near the top of the GUI (ex: Platform, Sessions, etc). Let "bottom" refer to the bar below "top" that contains a line of buttons (hover over them to reveal their labels; starting with "Configuration" on the left).
- In top, select: Platform > Connect
- In bottom, click on "Configuration" button.
- If configuration listed in the "Run Parameters" box is not FADC_prod: in top, select Configurations > Cool and change it to FADC_Prod.
- In bottom, click on "Download" button
- In bottom, click on "Prestart" button
- When ready to start run, click "Start" button. Typical run duration: 2 hours. Type in any Start Of Run comments in the box. Click "OK" (even if you left comments blank!).
- When ready to stop run, click "End" button. Type in any End Of Run comments in the box. Click "OK" (even if you left comments blank!).
Information for Compton Experts
- HV on/off? -> Compton#High Voltage Controls
- Rebooting components: Compton Reboot
- [Experts only]: Correct parameters for run in integratingDAQ.flags and compton.params
- Primary Lead Collimator
- Presently left fully open at 20 mm diameter.
- This is a 10 cm long collimator with inserts which can reduce aperture down to 10 mm or 5 mm in diameter.
- Synchrotron Shields
- For PREX-II a single 0.25 mm lead foil (painted) is taped to the front of the photon detector.
- Compton Jaws
- Remote access for experts can be found at 
- Note, for the duration of the PREX-II running period, the Compton Tungsten Collimator System ("Compton Jaws") will not be used. It should be left it is's parked position of:
aperture = 1.5 mm y center = -46.0 mm
Detector Positioning System
- Centering Beam & Photon Detector
- Refer to section [Compton Photon Detector Centering Procedure] for more info.
- For controls, troubleshooting: Compton Photon Detector
- Home position of photon detector table:
|Date||X [mm]||Y [mm]||Comment|
High Voltage Controls
- HV Control GUI
- GUI can only be accessed once per person. We share this GUI with Moller Polarimeter.
LED System (Linearity Measurement System)
- Will add info on MiniMegan soon
Taking an LED run:
- Find parameter file GUI:
$ cd /home/compton/franklin/ $ ComptonConfig
- Click "Pulser On, Pulser Trigger" on parameter file. Click "Apply", then "Done" to close GUI.
- Go to CODA. Start a new run to apply the settings. (This does not need to be a long run. You may end it immediately.)
- Start your LED run.
- When you go back to normal Compton runs: don't forget to turn the pulser off and do a short run to update the parameter file settings!
Software & Data Analysis
Relevant files, scripts, etc.
Run Compton analysis:
$ cd /home/compton/online/CompMon
Run analysis software:
$ ./compmon <run number, no brackets>
$ root -l /data/cmuwork/rootfiles/Fall2016/compmon_<run number, no brackets>.root
Run desired C script located in CompMon directory.
Some useful analysis scripts:
- /home/compton/lthorne/CompMon/plotAsymSpectrum.C: Quick and dirty view of asymmetry histograms, cavity and BCM limits.
- /home/compton/lthorne/CompMon/buildQuartets.C and buildQuartetsPlot.C: For constructing multi-run asymmetry plots.
- Run instructions are given in the comments at the beginning fo the file.
- /home/compton/lthorne/CompMon/BCMCal/calibration<runNumber>,C: BCM calibration scripts for specific runs.
- /home/compton/lthorne/CompMon/plotAccQuartets.C: plots sum, difference histograms for beam off, laser on, laser off for Acc0, Acc4.
- /home/compton/franklin/CompMon/plotPulser.C: peek at DAQ pulser channels, including info on 'variable' and 'delta' for channel 13.
Link to list of good Compton runs:
List of runs with comments, so know which ones were not junk.
Juan Carlos Google Docs: Runlist (Email Juan Carlos if you want to granted write permission)
From within NewTools controls (see first few steps in Compton Photon Detector Compton GUI section):
- On far right of JTabs menu, there are "master" controls. Find and click on Tools Screen.
- Go to the helicity controls. (The default is delayed, so be careful of this.)
As a brief check, run plotAsymSpectrum.C.
See last list entry for most recent meeting.
- Meetings before 2014
- 2014 Meetings
- 2015 Meetings
- 2016 Meetings
- 2017 Meetings
- Monday, February 12, 2018, 11:00 am EST - Compton Electron Detector
- Monday, February 19, 2018, 11:00 am EST - Compton Electron Detector
- Thursday, May 10, 2018, 10:00 am EDT - Compton
- Thursday, May 24, 2018, 10:00 am EDT - Compton
- Thursday, June 14, 2018, 10:00 am EDT - Compton
- Thursday, July 5, 2018, 10:00 am EDT - Compton
- Thursday, July 19, 2018, 10:00 am EDT - Compton
- Thursday, August 9, 2018, 10:00 am EDT - Compton
- Thursday, August 23, 2018, 10:00 am EDT - Compton
- Thursday, September 6, 2018, 10:00 am EDT - Compton
- Wednesday, September 19, 2018, 11:00 am EDT - Compton
- Wednesday, October 17, 2018, 11:00 am EDT - Compton
- Wednesday, November 7, 2018, 11:00 am EST - Compton
- Wednesday, November 28, 2018, 11:00 am EST - Compton
- Wednesday, December 12, 2018, 11:00 am EST - Compton
- Wednesday, January 9, 2019, 11:00 am EST - Compton
- Wednesday, January 23, 2019, 11:00 am EST - Compton
- Wednesday, February 6, 2019, 11:00 am EST - Compton
- Wednesday, February 27, 2019, 11:30 am EST - Electron Detector
- Wednesday, March 20, 2019, 11:00 am EST
- Wednesday, April 17, 2019, 11:00 am EDT
- Wednesday, May 1, 2019, 11:00 am EDT
- Wednesday, May 8, 2019, 11:00 am EDT
- Wednesday, May 22, 2019, 11:00 am EDT
- Wednesday, May 29, 2019, 11:00 am EDT
- Wednesday, June 5, 2019, 11:00 am EDT
- Wednesday, June 12, 2019, 2:30 pm EDT
Current Compton Experts
|Juan Carlos Cornejo (Photon Detector)||x5282|
For expert monitoring and troubleshooting information please visit Compton Expert Information.
Code can be found on github: https://github.com/JeffersonLab/HallA_CompMon JC says:
The Makefile is ancient (since it has to work on old systems too) but there is an easy "fix". In the src/config.d directory, create a file similar to cornejo_compton_jlab.conf but modify the paths respectively. Then run ./config config.d/<your_config_file> It will update the silly Makefile accordingly
Some old data and examples can be found on
Old Compton page (pre-Spring 2016)
Last edit on 2019 06 24, by Cornejo