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Muon system Survey are we at the right position? Follow up of last week’s presentation (updated version of March 22, 2012 with only the essential numbers…). Burkhard Schmidt Important feedback from Stefania and Giuseppe acknowledged. Strategy of alignment 2012.
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Muon system Surveyare we at the right position?Follow up of last week’s presentation(updated version of March 22, 2012 with only the essential numbers…) Burkhard Schmidt Important feedback from Stefania and Giuseppe acknowledged
Strategy of alignment 2012 • Understand survey 2012 and apply the right corrections based on the 2011 software alignment before the start of data-taking in order to bring M1-M3 to the optimal position • Avoid asymmetries between A- and C-side • Take M2 as reference to determine optimal position for M3 and M1. • Comments: • Keep in mind that the Muon stations cannot be closed fully due to the muon filters, which cannot be closed completely. • The resulting opening of M2 is about 8mm. • Stations M4 and M5 are less important and their position has not been optimized in the following.
Comparison of software alignments corrected for survey differences • The 1stand 2ndcolumn show a very similar tendency for the corrections in the SW alignment 2011 and the survey, so the differences (3rd column) are small. • The survey corrected software alignment for 2011 (3rdcolumn, light blue) is used for the analysis of the survey for 2012.
Muon system alignment in 2012 • The ideal position for the stations has been calculated using projectivity, based on the optimal offset for M2. • The corrections to be applied are the sum of those indicated in green (deviations form ideal) and blue (result of SW alignment 2011, survey corrected (cf. slide 4)). • Applying these on the measured offset for 2012 (4th column top), leads to the calculated offset (5th column top).
Muon system alignment in 2012 • The calculated corrections to optimize the position for the half-stations have of course some uncertainty (not estimated here).
Conclusions • Preliminary conclusions for 2012 based on this study are as follows: • The offset for M2 (A- and C-side) could be reduced to 7.7mm (was 8.5mm in 2011). • A opening of M1C by about 2.8mmis strongly supported by both, the survey and the analysis of the alignment data. Taking into account the slope between M2 and M3, this becomes about 3.5mm. • Also M1A needs to be opened by about 1.6mm. Taking into account the slope between M2 and M3, this becomes about 1mm. • M2+M3 A and C-side are in a good position and should not to be touched. M4 and M5 A and C-side are too opened, but we don’t care.