Calibrating Cavity BPMs (Invasive)

Go to lclshome  > UND BPMs > Cavity BPM Calibration...

This launches the Main display.  From here, you can open user interfaces and diagnostic displays.

  • From Cavity BPM Calibration - Main, launch the Calibration Data Acquisition...display.
  • Select the BPMs and planes you want to acquire data for by clicking individual boxes or using the Select all..., Deselect all... buttons.
  • Set the scan range (0.2 mm is the default).
  • Open the Acquire calibration data... display, which will prompt you to confirm by pressing the Start scan button.

This launches a matlab script which will turn off the UND launch feedback, move undulator girders and/or LTU correctors (depending on which BPMs you've selected), acquire data, and return the UND launch feedback to its initial state.  The scan will take <1 hr (exact time depends on the number of BPMs selected).  This requires beam to the main dump for the duration of the scan.  If beam to the dump is interrupted during the scan, the script will pause and wait for your input before resuming.

At the end of the scan, you will be prompted to implement a calibration.  You have three choices: implement full calibration (type 'y'), implement partial calibration (type 'p'), do not implement the calibration (type 'n').  If you choose a partial calibration, you will then need to go to the Plot/Implement Saved Data... display, select the BPMs/planes you want to implement a calibration for, and then type 'go' at the matlab prompt.

At the end of the scan, the calculated calibration parameters will be printed to the console and the X/Y scale changes will be plotted.  Please put these in the physics logbook.

Implementing Saved Calibration Data (INVASIVE)

  • From Cavity BPM Calibration - Main, launch the Plot/Implement Calibration Data... display.
  • Select the BPMs and planes you want to implement a calibration for by clicking individual boxes or using the Select all..., Deselect all... buttons.
  • Open the Implement calibration... display, which will prompt you to confirm by pressing the Calibrate button.

This opens matlab, prompts you to choose a saved data file, then implements the saved calibration parameters for the BPMs you have chosen.

Plotting Saved Data (NOT INVASIVE)

You can also plot saved calibration data.

  • From Cavity BPM Calibration - Main, launch the Plot/Implement Calibration Data... display.
  • Press the Load File and Plot Data button.

This opens matlab, prompts you to choose a saved data file, then plots the calibration data from that file.

Plotting Summary of Saved Data (NOT INVASIVE)

You can also plot just the X and Y scaling factor changes.

  • From Cavity BPM Calibration - Main, launch the Plot/Implement Calibration Data... display.
  • Press the Load File and Plot Summary button.

This opens matlab, prompts you to choose a saved data file, prints a list of results and plots the X and Y scaling factor changes.

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