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 22 February 20091M1 Alignment T.Schneider M1 Alignment

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 22 February 20092M1 Alignment T.Schneider Preparation of wall position

22 February 20093M1 Alignment T.Schneider Preparation of wall 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 22 February 20094M1 Alignment T.Schneider 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 22 February 20095M1 Alignment T.Schneider Alignment of A and C side in closed position

M1 closing

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

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

22 February M1 Alignment T.Schneider Translation 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 22 February M1 Alignment T.Schneider Transfer of reference system to open position

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 22 February M1 Alignment T.Schneider Balcony alignment

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 22 February M1 Alignment T.Schneider Alignment for X Y and horizontal level

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

22 February M1 Alignment T.Schneider 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.

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 22 February M1 Alignment T.Schneider Interlink of Front and Back alignment Side view top Side view bottom Back Front

22 February M1 Alignment T.Schneider Sequence for Alignment procedure Rich detector

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

22 February M1 Alignment T.Schneider Sequence for Alignment procedure M1 back side 2 nd 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

22 February M1 Alignment T.Schneider 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 2 nd step the far one