Preparation of wall position Alignment of A and C side in closed position

1. M1 Alignment Preparation of wall position Alignment of A and C side in closed position Creation of reference system Translation of reference system to open position Balcony alignment Alignment system for X, Y and horizontal level Interlink of Front and Back alignment Sequence for Alignment procedures Conclusion for the M1 alignment system M1 Alignment T.Schneider

2. Preparation of wall position End of last year we had a first look on the absolute position of the M1 A and C side Looking on the beam pipe position we had to lift both sides up by about 4cm With the help of the survey team we measured the beam supporting the walls M1 Alignment T.Schneider

3. Preparation of wall position M1 Alignment T.Schneider

4. Alignment of A and C side in closed position The walls were put in a kind of “close to closed” position (25cm) With the help of a plump we aligned the inner edges of both sides vertically M1 Alignment T.Schneider

5. Alignment of A and C side in closed position The system has been closed totally The beam pipe cut out was well adjusted in X and Y around the beam pipe This position is the starting point for our alignment. About the shape of the walls we do not care so much. We need a kind of reference system visible in open and closed position M1 Alignment T.Schneider

6. M1 closing

8. Translation of reference system to open position M1 Alignment T.Schneider

9. Translation of reference system to open position M1 Alignment T.Schneider

10. Translation of reference system to open position M1 Alignment T.Schneider

11. Transfer of reference system to open position After the opening of the system (working position) the reference system has been brought again into vertical position. This we have been done by adjusting the outer fixation screw of the walls. The resulting difference in Y has to be taken into account (A=-3.25mm,C=-4mm) For the translation in height (Y) of Survey coordinate system to the physics one a correction of 43.6mm (depending on Z of M1) is given M1 Alignment T.Schneider

12. Balcony alignment Using this reference system we were able to measure the end of chamber fixation rail positions All front side top and back side bottom positions were measured . Some additional ones (back top) were used for crosschecking. These coordinates once translated to absolute values for the closed position were the starting point for Wander to do the balcony alignment for the close chambers M1 Alignment T.Schneider

14. Alignment for X Y and horizontal level Alignment bars with precise holes at the nominal chamber centers positions (X) have been machined 4 different types are need These bars will be fixed and well aligned on the top and bottom of the walls Precision rods will be inserted into these holes Thin wires fixed between these rods will built a kind of grid system for the X–position of the chamber centers Additional square bars on top of these rods will guarantee good reflection for the Y laser distance measurement With help of additional traces on the chambers we will be able to align the horizontal level of each chamber M1 Alignment T.Schneider

15. Alignment for X Y and horizontal level Alignment steps: Y-alignment measurement with laser meter to top and bottom square block Horizontal level alignment with precision water level X-alignment with help of wire grid M1 Alignment T.Schneider

16. Alignment for X Y and horizontal level Calibration of new laser meter The new laser meter mode has a 0.1 mm digit compared to 1mm from the old one. It has been compared to an interferometer of the SU group. We should include a linear correction for the Y-measurement. M1 Alignment T.Schneider

17. Interlink of Front and Back alignment Side view top Important point is to interlink together Front and Back alignment in the best way possible The bottom front area is unfortunately not accessible for any survey measurement For the top bars we will link directly front and back together . This is done via additional rods passing the wall For the bottom of the wall this is unfortunately not possible due to the cable routing already done. For the bottom front ones we will also pass the wall with precision rods give access for the survey measurement Front Back Side view bottom M1 Alignment T.Schneider

18. Sequence for Alignment procedure Rich detector M1 Alignment T.Schneider

19. Sequence for Alignment procedure M1 Back side 1st step: M1 in open position Alignment of B/C/D column M1 Alignment T.Schneider

20. Sequence for Alignment procedure M1 back side 2nd step : Calorimeter in open position and M1 more or less closed Alignment of A-column The access to the chamber crosses is good The walls have to be re-aligned for the horizontal level M1 Alignment T.Schneider

21. Conclusion for the M1 Alignment system • Improvements for the M1 alignment: • Permanent reference system on the wall easy visible for survey • Good interlink in-between reference system and alignment system • Precision (+-0.1mm) alignment bars on top and bottom of the wall • Front and back alignment will be well interlinked • The new laser meter has one digit better resolution (1mm=>0.1mm). Measurement to top and bottom • The reflection surface for the Y-measurement has been improved • We have no more free hanging plumbs but a more precise and stable wire grid for the X alignment • Chamber cross quality has improved • Alignment with nacelle to reach each chamber • Inner part Front very bad access (not possible to climb down) • Faraday cages in the way for Y and X alignment • First align close layer and then in a 2nd step the far one M1 Alignment T.Schneider