Issues with Alignment of "transposed" detectors using the KFA

[YannickDieter]

Issues in detector alignments of "transposed" detectors were observed with the Kalman Filter Alignment resulting in diverging alignment parameters.

A transposition results into the following possible euler angles ('xyz'):

• [-pi, 0, -pi / 2.0]
• [pi, 0, -pi / 2.0]
• [0, pi, pi / 2.0]
• [0, -pi, pi / 2.0]

None of these starting values results into a successful alignment using the KFA.

The proposed solution is either to:

• transpose your data before the actual analysis or,
• use the regular alignment which might lead to a residual offset in one direction

NB: The problem seems to be a rotation of alpha or beta by +- pi. The Alignment of heavily rotated devices could be confirmed

[YannickDieter]

@cbespin Can you report your findings here, too?