Laser Design Review, CERN, 27 Jan 2003 Børge Svane Nielsen, NBI 1 TPC Laser system Functions of the system Basics of the design Construction tolerances and alignment Lab tests at NBI Status of system components Production status and installation Design Review, CERN, 27 January 2003 Børge S. Nielsen, J.J. Gaardhøje, N. Lindegaard and Jørn Westergaard Niels Bohr Institute A. Lebedev, Brookhaven National Laboratory
TPC Laser system. Design Review, CERN, 27 January 2003 Børge S. Nielsen, J.J. Gaardhøje, N. Lindegaard and Jørn Westergaard Niels Bohr Institute A. Lebedev, Brookhaven National Laboratory. Functions of the system Basics of the design Construction tolerances and alignment - PowerPoint PPT Presentation
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Functions of the system Basics of the design Construction tolerances and alignment Lab tests at NBI Status of system components Production status and installation
Design Review, CERN, 27 January 2003Børge S. Nielsen, J.J. Gaardhøje, N. Lindegaard
limited space between TPC and space frame move beam transport 10º from vertical plane adds 2 mirrors on shaft side + modifies beam transport on muon side
attach 50 mm pipe on outside of TPC permanently
special prismspecial prism
”knee” in beam transport on shaft side”knee” in beam transport on shaft side
”standard” prism”standard” prism
Muon sideMuon side
Shaft sideShaft side
We are currently considering to move back into the vertical planeWe are currently considering to move back into the vertical plane
Remote setup and monitoring of laser CCD cameras for beam positioning: entrance mirrors on end plates end points on end plates end of laser rods Remote beam manipulation: 4 mirrors in laser hut 1 entrance mirror on each end plateData taking:
Test + special calibration runs: trigger from laser trigger laser ( several μs @ 10 Hz) Normal physics runs: low rate trigger from laser
Construction tolerances and alignment accuracy (1)
Construction tolerances and alignment accuracy (1)
What is known precisely and ’absolutely’ during construction? (100-150 m)
pad plane z and wire z and x/y position central electrode z position
Well measured relative to each other (100-150 m, 0.05 mrad): internal dimensions and angles in micro-mirror bundles micro-mirror bundles in support rings bundle support rings in uninstalled rods
Less well measured or prone to move during handling (500 m, 0.2 mrad):
rod positions relative to ROCs, central electrode and ALICE x,y,z
Construction tolerances and alignment accuracy (2)
Construction tolerances and alignment accuracy (2)
’Internal alignment’ and iterations (offline analysis) : electrons from central electrode ’absolute’ z electrons from ROC pad plane and wires ’absolute’ z, x/y laser tracks close to outer rods good relative alignment laser tracks are straight lines iterate to best ’absolute’ positions of laser rays track time variations
Additional alignment relative to end plates with horizontal and loaded TPC (100-200 m, 0.05 mrad):
measure rod / micro-mirror bundle positions by survey through rods (fiducial marks useful) measure some beams near inner cylinder with HeNe laser after rod installation
1 mm quartz fibrescut at 45º, polished, coated7 micro-mirrors/bundle
All 60 bundles produced and delivered in September 2002, but problems with surface quality on some mirrors and mechanical precision on some cups preliminary: 46 accepted based on surface quality most of these will be accepted after being
Notes and presentations: http://www.nbi.dk/~borge/tpclaser/
Rod system: Micro-mirror bundles: ready ~1 Feb 2003 Mirror support rings produced Mirror testing: ongoing, fall 2002 + beginning 2003 Rod production at CERN: spring 2003
Optics system: Principle design: done Detailed design: spring 2003 Production and installation: mid 2003 - spring 2004
Commissioning: Together with TPC chambers: 2nd half 2004 + 2005