ess.spectroscopy.indirect.conversion.rotate_to_sample_table_momentum_transfer#

ess.spectroscopy.indirect.conversion.rotate_to_sample_table_momentum_transfer(*, a3, lab_momentum_transfer, gravity)[source]#

Rotate the momentum transfer vector into the sample-table coordinate system

Here, the momentum transfer is defined as

\[\vec{Q} = \vec{k_i} - \vec{k_f}\]

Note

When a3 is zero, the sample-table and lab coordinate systems are the same. That is, Z is along the incident beam, Y is opposite the gravitational force, and X completes the right-handed coordinate system. The sample-table angle, a3, has a rotation vector along Y, such that a positive 90-degree rotation places the sample-table Z along the lab X.

Parameters:

  • a3 (Variable) – The rotation angle of the sample table around the laboratory Y axis

  • lab_momentum_transfer (Variable) – The momentum transfer in the laboratory coordinate system

  • gravity (Variable) – The gravity vector which indicates the vertical axis.

Returns:

Variable – The momentum transfer in the sample-table coordinate system.