TRT L2 Alignment
The TRT L2 alignment has been done in serveral ways and there are two lingering issues.
1) TRT L2 alignment cannot resolve A/C local misalignment.
2) Different geometries are reached depending on weather Si information is used or not.
Click here for details about the TRT Only L2 Alignment.
Click here for details about the TRT L2 alignment with combined tracks.
L2 Alignments in the db
There are several L2 TRT alignments in the db
Click here for details
Comparing TRT L2 Alignments
When summing over all cosmic tracks, standard monitoring plots are inconclusive as two which set of constants are to be preferred. (although the coherent elliptical distortion is a result of the alignment with combined tracks) The current alignment "blessed" by the alignment group is the L2 using the combined tracks in 5DoF which is very similar the one in 3DoF.
Important to determine which is better, if the TRT-Only, this seems to point to some for of elliptical deformation in the Si. The following represent the differences in TRT L2 Alignment parameters (at least the translations) when aligning in 3DoF with TRT only tracks vs combined tracks.
Effort to compare L2 geometries presented here.
This needs more documentation. It looks like there is a residual effect (at L2?) that is bigger than the differences between the L2 alignment sets.
