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Spring 2016 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)

Operation Guide

Instructions for shift workers to run Compton.

  1. Pre-check:
    1. HV on/off? -> Compton#High Voltage Controls
    2. [Experts only]: Correct parameters for run in integratingDAQ.flags and compton.params?
  2. Start CODA:
In compton@compton: startcoda
A few new Terminal windows and a GUI pop up.
LT CODAgui.png
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).
  1. In top, select: Platform > Connect
  2. 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.
  3. In bottom, click on "Download" button
  4. In bottom, click on "Prestart" button
  5. When ready to start run, click "Start" button. Most runs are typically ~2 hours.
  6. When ready to stop run, click "End" button
To close CODA and kill all related processes, type kcoda.
  1. Run Compton analysis:
    1. In compton@compton: cd /home/franklin/CompMon/
    2. Run analysis software: compmon [insert run number here, no brackets]
    3. Open ROOT: root lnkCompMon.output
    4. Run desired C script located in CompMon directory: .x [insert scriptname here, no brackets]. Currently, we are interested in seeing the raw asymmetry, so run .x plotAsymSpectrum.C.
    5. Sip and admire.


Electronics, etc.

Photon Detector Table

For controls, troubleshooting: Compton Photon Detector

High Voltage Controls

Know the HV channel and navigate to the GUI: HV Control GUI

Laser System

Real time o-scope signals

Make sure laser flipping is on

Turning off the laser

IOC reboot

Accessing the laser hutch in the hall

Laser and Locking troubleshooting

Software & Data Analysis

Relevant files, scripts, etc.

Helicity controls

From within NewTools controls (see first few steps in Compton Photon Detector Compton GUI section):

  1. On far right of JTabs menu, there are "master" controls. Find and click on Tools Screen.
  2. Go to the helicity controls. (The default is delayed, so be careful of this.)

Current Scripts

As a brief check, run plotAsymSpectrum.C.


Compton Meetings

See last list entry for most recent meeting.

Current Compton Experts

Expert Phone
Dave Gaskell x6092
Alexandre Camsonne x5064
Ciprian Gal x6235

Expert Information

For expert monitoring and troubleshooting information please visit Compton Expert Information.

Old Compton page (pre-Spring 2016)

See Pre-Spring 2016 Compton

Last edit on 2016 06 07, by Gaskelld