Goniometer calibration on TOPAZ

[Vickie Lynch]

The TOPAZ goniometer calibration is currently using an ISAW algorithm for finding and refining the goniometer offsets (in chi, phi, omega). This algorithm works very well and reliable. We found that well calibrated goniometer zero positions are critical to high quality structure refinements due to stitching a substantial number of settings together in a quantitative manner.

However, trying the same calibration to find and refine goniometer offsets in Mantid does not give us a number unless the offset is very large. The Mantid algorithm does not have sufficient sensitivity.

This should be straight forward: A well working algorithm exists in ISAW and it is only necessary to copy the algorithm into the Mantid framework to produce the same results.

We need to use this calibration every time we change sample environment and swop goniometers. We will do this more frequently from the next cycle on when we have an ambient and a cryogenic goniometer.

For the corrections the runs TOPAZ_10116 - TOPAZ_10127 were used. The settings were verified with TOPAZ_ 10220 to 10231.

Xiaoping has the done the data reduction, calculated the offsets and has the details. For further details please contact Xiaoping.

[Vickie Lynch]

Refs #10199 use same cost function as ISAW

Changeset: 0cd3ae9e217d9d1736083b2b4e1bbed4cac0b2b3

[Vickie Lynch]

Revert "Refs #10199 use same cost function as ISAW"

This reverts commit 0cd3ae9e217d9d1736083b2b4e1bbed4cac0b2b3.

Changeset: 22c434b6ef0dc3fcfa7b47db51731aeac8024a54

[Vickie Lynch]

Revert "Revert "Refs #10199 use same cost function as ISAW""

This reverts commit 22c434b6ef0dc3fcfa7b47db51731aeac8024a54.

Changeset: 36fc1f8da9120a97dcf81ffe3a066f124b665393

[Stuart Campbell]

This ticket has been transferred to github issue ​11041