Large dynamic range small-angle diffractometer

Q-range macro for GEORGE

Macro written by J. Anselmino, May 2001

Q-RANGE serves four purposes: <nl&g

  • to define instrument settings for scattering (and transmission) measurements
  • to calculate the corresponding Q ranges and real-space dimensions
  • to execute setting commands directly by MAD
  • to optionally save the settings in MAD command files setting_1.cmd to setting_9.cmd and setting_t.cmd

How to proceed

Get the current instrument configuration ("Get Instrument Setting" button), select an existing setting file by choosing its radio button, or simply fill in your values in the fields "Wavelength", "Detector Distance" and "Offset", and select a Beamstop number button.

Push the "Calculate" button to display values for estimations of

  • the minimal and maximal distance (radius) of the scattered beam from the beam centre
  • the corresponding values for the momentum transfer Q
  • the corresponding values of the maximal and minimal dimensions in the sample that can be resolved with this setting.

Complete the setting information by choosing the collimation, the beamstop position Bx and By, the beam centre values X0 and Y0 (in pixels) and the detector rotation angle. We recommend that you use 99 for Bx and By if they have not been determined, and to leave the detector angle at 0.

Once all this done, you can use the "Send" command to execute the complete setting immediately by MAD that must be idle. 
Note that a necessary beamstop change will not be executed automatically for reasons of safety.

You can also use the "Save setting" button to write a MAD compatible command file named setting_n.cmd, with n = 0-9 or t: Type a value of 0 (for t, transmission setting) to 9 in the field to the right of the button. The MAD "beam" command will be commented in the command file.

NB: Unlike other warnings, the one concerning an inappropriate collimation value does not prevent you from storing a setting file nor sending the MAD commands!

Web document produced by Roland May, ILL Grenoble (last update: 18-Jun-2001)