GDA

Owned by Liam Perera
Last updated: Jul 17, 2024
4 min read

GDA is a user interface for the beamline. It provides a streamlined interface for all experiment operations and data acquisition.

It is organised into perspectives, which allow the user to switch between different modes of operation, e.g. diffraction and tomography. Each perspective is logically arranged into different tabs, which split up the functionality.

Start GDA by typing the following in a user workstation terminal:

gda client

 

The following window will initiate momentarily.

image-20240628-125330.png

The typical workflow is:

  1. Start the Experiment

  2. Center your sample

  3. Work out the best exposure for the diffraction and imaging detectors

  4. Create single or multiple scan recipes using the optimal parameters

  5. Run the scan/s

DASHBOARD: SETUP PANEL

Purpose: Set up and optimise collection and sample centering.

  1. Experiment name – This is an ID under which all scans will be grouped. Experiment must be started to collect data.

  2. Acquisition Type – Diffraction or Imaging

  3. Beam Selector – Diffraction or Imaging

  4. EH Shutter – Open/Closed

  5. GTS Positions.

Left box is set value in mm, right box is step value in mm (can be changed). Motion is stepped using up/down arrows.

  1. Cameras
    Exposure time is optimised here. Camera streams are turned on using green button. Bright green is on. Red means fault.
    Imaging Camera – 0.001 to 1.9 sec
    Diffraction Camera – 1-60 seconds.
    image-20240716-104244.png IMPORTANT – if changing diffraction camera exposure time – turn off monitor before making the change.

image-20240716-103951.png

 

CAMERA STREAMS

Purpose: to display a live camera stream (diffraction or imaging)

 

Imaging:

  1. Default stream tab is a jpeg stream – do not use this for centering/optimising exposure.

  2. Click cameras button in Setup panel and this will open a new ‘Camera Configuration’ Tab.
    Note: when pressing Cameras button – new stream tab can open elsewhere

  3. Set detector to imaging or diffraction camera and stream to Epics PV Access.

  4. If shutter is open and camera is on this should produce live stream of sample.

  5. A histogram is available to aid understanding.

 

 

SCAN CONFIGURATION: TOMOGRAPHY

Purpose: Set up scan recipes. Once saved these can be re-run at any point for any sample/experiment.

Diffraction

  1. Name: eg Diffraction_Spot

  2. Acquisitions: Diffraction, Point and Shoot, Diffraction Tomography, Beam Selector.

  3. Geometry:

    1. Point, Line or Grid or use draw tool.

    2. X,Y Positions in pixels

    3. Number of points (if line or grid)

  4. Step/Continuous: Beam movement between scans. Usually always stepped.

  5. Alternating – speeds up collection if doing grid – but make note for correlating scan no with image.

  6. Exposure: in seconds. 1-30 seconds

  7. Post processing: Configure to dawn post processing.

  8. Saved Definitions: Scans that are saved will be found here. Simply select the scan, the parameters will load into panel and then click run to submit the scan.

 

A scan is submitted using the Run button.

 

 

 

Purpose: reports status of job queue including past and ongoing scans. Returns error messages if scan fails.

Scans are submitted using the Run button in the Configuration panel above the queue.

Stop job - The stop button can be used or you can right click any running or submitted job and select stop or pause job.

Rerunning Jobs - if you right click any job you can select re-run job at which point you specify how many times it will be submitted.

Errors - The Message column will return whether a scan completed or failed. It will give an error message that is used to diagnose the reason for failing. Common Errors: