MDI alignment progress - slac.stanford.edu · MDI alignment progress The pre-alignment of the...
27
MDI alignment progress The 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 2012 Fermilab, Sept 13, 2012
Transcript of MDI alignment progress - slac.stanford.edu · MDI alignment progress The pre-alignment of the...
MDI alignment progress The 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 2012
Fermilab,
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 charged
particles 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…..!
Instead: use space away from beam tube,
at larger R:
alignment in two steps:
- Reference Rings
- (double) anti // Rasniks
Monitor X,Y of (both) QD0 end ref’s with respect to RR
(with Rasniks)
to be calibrated
on 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
Steel
ball Zerodur rod (6 mm x 6 mm x 3500 mm
spoke support tube: flexo suspension
Inner spoke detail Outer spoke detail
Precision ring QD0 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 System
versus RasDif (TT1)
RasChain: interconnected Rasnik systems
for 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
