Setting the UB Matrix

The UB matrix describes how reciprocal lattice coordinates are oriented on the diffractometer. The B matrix is determined by the lattice constants and converts (h, k, l) from reciprocal lattice units to Cartesian reciprocal-space coordinates. The U matrix describes how the crystal is mounted relative to the diffractometer sample circles.

orGUI provides two complementary workflows:

Manual reflection setting

The user selects known reference reflections in detector images, assigns hkl values, and calculates U from one or more measured reflections. This is the most transparent workflow and is the best way to diagnose detector, scan-axis, or indexing problems.

Automatic UB setting

orGUI streams through the scan images, detects a sharp Bragg-like peak, assigns candidate hkl values, builds a one-reflection trial U matrix, confirms that matrix with another predicted Bragg peak, and optionally adds more validated reflections.

• Manual Reflection Setting
  • Reference-Reflection Method
  • Reflection Edit Controls
  • Adding Calculated Bragg Reflections Manually
  • Expert Matrix Editing
  • Validation
  • Reference-Reflection Mismatch Coloring
• Automatic UB Setting
  • Prerequisites
  • Overview of the Automatic Workflow
  • Automatic Bragg Options
  • Status Dialog and Additional Reflections
  • What Is Added to the Reflection Table
  • Failure Modes and Practical Checks