MDI alignment progress The pre-alignment of the QD0’s Niels van Bakel, Bram Bouwens, Hubert...
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Transcript of MDI alignment progress The pre-alignment of the QD0’s Niels van Bakel, Bram Bouwens, Hubert...
MDI alignment progressThe pre-alignment of the QD0’s
Niels van Bakel, Bram Bouwens, Hubert Gerwig, Lau Gatignon,Harry van der Graaf, Henk Groenstege, Joris van Heijningen, Jan Koopstra,Helene Mainaud Durand,, Richard Rosing, Vivien Rude CERN, Nikhef
IWAA 2012Fermilab,
Sept 13, 2012
X
Y
X
Y
X
Y
Alignment of two objects:- omit Z- omit rotZ
Measure:- translation X- translation Y- rotX-rotY
-Equivalent to-4 points (X,Y)
Momentum Measurement of chargedparticles in the L3 experiment:Chamber Position Monitoring
• Lorentz Force:• Track Curvature measurement
Detector
Muon Particle Track
Detector
Detector
Direct measurement: two anti // Rasniks:
light source + image sensor
lens
… would only require path of sight of 20 mm2….…. along beampipe…..!
Monitor X,Y of (both) QD0 end ref’s with respect to RR(with Rasniks)
to be calibratedon 3D measuring machine
Rasnik Lines-of Sight
spokes
Reference Ring RR
Spoke
- length 3.5 m;- has only one function: to transfer radial position better than 1 μm
Material: Zerodur: thermal expansion coefficient < 0.2 x 10-6
Alignment is NOT influented by:
- (common) deformation of RRs (sag, spoke load)- temperature of individual RR- (common) deformation of spoke wheel (spoke weight compression)- temperature of individual spoke wheel
Spoke tip on RR side: contact definition < 0.1 μm
Steelball Zerodur rod (6 mm x 6 mm x 3500 mm
spoke support tube: flexo suspension
Inner spoke detailOuter spoke detail
Precision ringQD0 support tube
Volume reserved for support plate of Rasnik/Rasdif
Radial retraction for endcap opening
1983: 4QD Red Alignment System Nikhef (Rasnik)
1993: CCD Rasnik
2003: RasDif: long distance
Comparison Stretched Wire Systemversus RasDif (TT1)
RasChain: interconnected Rasnik systemsfor basic CLIC units of 2010 mm
MDI/QD0 alignment: vibrations
- new (green) semiconductor lasers- shielding- image analysis software
diffraction plate simulated measured
Thermal shielding of light path