Roman Pot Alignment

This page describes the SW tools contributing to the alignment of the TOTEM Roman Pots. The key modules are

  1. data formats (TotemAlignment/RPDataFormats),
  2. track-based alignment (TotemAlignment/RPTrackBased) and
  3. profile alignment (TotemAlignment/RPProfiles)

Track-based alignment

RPStraightTrackAligner

... to be written

Alignment file format (XML)

The file consists of a list of tags, each tag describes an alignment correction of an element, according to this table:

tag element
rp Roman Pot
det Si sensor
The alignment corrections are additive, that is the full correction for a Si sensor is obtained by combining the corrections from the det and the corresponding rp tag.

An element identified by its id attribute, which gives the decimal ID. The alignment correction is described by the attributes summarized in the following table:

attribute meaning
sh_r shift in the read-out direction (only for det tags)
sh_x shift in x direction
sh_y shift in y direction
sh_z shift in z direction
rot_z rotation about the z axis
The z axis follows the beam, x points outside the LHC ring, y goes up. The shift parameters are given in micrometers, the rotation ones in miliradians. For every attribute, there is an associated one with _e suffix, giving the uncertainty of the parameter.

ModifySingularModes

This plugin can be used to change the values of the singular modes (i.e. those that cannot be determined by the track-based alignment):

  • unit shift in x (de_x parameters)
  • unit shift in y (de_y parameters)
  • unit rotation about z (de_rho parameters)
The shift/rotation parameters are specified at two z positions (z1 and z2) parameters.

An example config file can be found in TotemAlignment/RPTrackBased/python/ModifySingularModes_example.py.

The input and output parameters give the file names of input and output alignment XML files.

Profile alignment

... to be written

-- JanKaspar - 07-Sep-2010

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Topic revision: r4 - 2012-03-27 - JanKaspar
 
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