1. LiCAS train simulations (current status of work done at Oxford) Grzegorz Grzelak

2. Simulation Software Simulgeo: simulation and reconstruction software for optogeometrical systems. (L. Brunel, CMS note 1998/079) Many features: –Laser beams –CCD cameras –Mirrors –Distancemeters –... Description of mechanical support by grouping various objects into local frames

3. Simulation of single train 2 laser beams for SM 2 beam splitters per car 2 CCD cameras per car 4 internal FSI lines 2*6 external FSI lines -------------------------------- 1  m res. (all positions) 1  rad res. (all orientations) 1  m res. (all FSI and CCD) -------------------------------- Problem: Weak sensitivity to rotation Around z-axis (and y-coor. of the wall marker)

4. Single train (cont.) Even for very unrealistic assumption (0.1  m for CCD, 0.01  rad for relative alignment of two laser beams in SM)  Rotation around z-axis is still the weakest measurement !!!  Need to include the clinometre…

5. Single train + clinometre One axis tiltmetre (1  mrad res.) Now the position Along z-axis is The weakest parameter (this is OK)

6. Single train – no syst. errors In order to perform the Full simulation of longer Tunnel section the model must be simplified (CPU+MEMORY limit !) Here: the only source of errors comes from FSI and CCD (which are set to 1  m)  All output errors are scaled down by factor 2

7. More trains (15) 15 overlapping trains 2 wall markers in front of each car “boundary effect” at the ends of tunnel section  less overlap Surprise  Very steep growth of Transverse errors (x and y coord.) (can be explained even using much simpler model when drawing long line using short ruler)

8. Full simulation of 600 m tunnel 200  m over 600 m Seems to be feasible but very tough (REMEMBER: there are not systematic errors in this simulation) On the other hand: the relative misalignment of adjacent accelerator components are not so big  the points are strongly correlated !!!