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BE/ABP-SU/. Adjustment of 4 Drive Beam Quads positions on TM0 CLIC girders. BE/ABP-SU/. Contents. Introduction A priori data Fiducialisation Measurement devices Alignment procedures Supporting plate and shims Supporting plate equipped by screws Measurements results Conclusions.
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BE/ABP-SU/ Adjustment of 4 Drive Beam Quads positions on TM0 CLIC girders
BE/ABP-SU/ Contents Introduction A priori data Fiducialisation Measurement devices Alignment procedures Supporting plate and shims Supporting plate equipped by screws Measurements results Conclusions
BE/ABP-SU/ Introduction • The CLIC mock up, under assembly in the building 169, is at the moment composed by the supporting system of 2 modules Type 0 and recently by 4 Drive Beam Quads. • The goal of the measurements and adjustments performed early November was to align the 4 DBQ: 2 DBQ with respect to 1 girder axis. • Alignments were done according to the 2 methods proposed by Nick Gazis (either by wedging, or by using screws)
BE/ABP-SU/ A priori data Fiducialisation • Fiducialisation of Boostec girder in CMM Olivetti (accuracy MPE about 6 µm) • Fiducials on cradles not used during • DBQ alignment because of a • temperature about 23°C • Fiducialisation of the 4 DBQ (and associated BPM) in the CMM Leitz Infinity (accuracy MPE under 1 µm) Use of 4 fiducials during alignment • All components are mock-ups fiducialisation of the beam pipe
BE/ABP-SU/ A priori data Measurement devices • Fiducials CCR 1.5’’ holders glued on girders and DBQ • CCR 1.5’’ error of sphericity and centering less than 0.0001’’ (about 2.5 µm) • Laser tracker Leica AT401 accuracy about 7 to 10 µm rms in that kind of measurement volume
BE/ABP-SU/ Alignment procedures Supporting plate and shims • Vertical adjustment by 3 shims make DBQ unstable Using of 4 shims (not isostatic) • Lateral adjustment by using a mallet • Surprisingly not so bad! • Lateral gap between plate and girder doesn’t allow alignment disassembling of DBQ / plate, adjusting, assembling • Fixing the supporting plate to the girder by using screws creates lateral misalignment • Dynamic following of the fiducials during screwing • WARNING: Even after tightening, the DBQ can move if it is hit
BE/ABP-SU/ Alignment procedures Supporting plate equipped by screws • 3rd adjustment screw inaccessible • Vertical wedging • All lateral threads were out of range • Manually repairing in place • Mechanical part blocks the supporting plate • Longitudinal displacing • Lateral screws generate stress and misalignment • Return to first adjustment method
BE/ABP-SU/ Measurements results Z Z X X 3069 Y Y 3079 Final position of the DBQ beam pipe axis in the girder reference frame
BE/ABP-SU/ Conclusions • It’s a pity to accurately machine a supporting plate and to need to repair threads, to adjust lateral position (link DBQ / plate), etc. • Total alignment lasted about 4.5 days Now we could perform it again within 2 days. • Alignment tolerance of 20 µm is not respected for all DBQ. • We are limited by adjustment systems and not by measurement device. • If a new adjustment system is designed, we would like to take part to the mechanical design and we will be happy to try again to align DBQ.