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Status of laser system. Work and developments since October 2003: Assembly of full length laser rods Rod installation and measurements Status of quartz optics Status of mechanics Placement of equipment on the endplates DCS discussions. TPC meeting, Sardinia, 16-17 May 2004
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Status of laser system Work and developments since October 2003: • Assembly of full length laser rods • Rod installation and measurements • Status of quartz optics • Status of mechanics • Placement of equipment on the endplates • DCS discussions TPC meeting, Sardinia, 16-17 May 2004 Børge Svane Nielsen Niels Bohr Institute Børge Svane Nielsen, NBI
Laser system principle Børge Svane Nielsen, NBI
Rod gluing and installation • Drill holes in short rods: done • Mount mirror bundles in support rings: done • Glue mirror support rings onto short rods: done 4. Glue short rods into full length rods at CERN. done Scheduled to commence 20 October. alignment fixed during gluing, using green laser • Angle measurements on final rod possible in lab at CERN before installation, using same green laser done • Angle measurements possible again during rod installation in field cage, using same green laser done • Re-measurements with TPC in final orientation Børge Svane Nielsen, NBI
Full length rod gluing Rods with pre-mounted laser mirrors were glued to full length TPC rods, using green laser fitted with telescope to produce 20 mm beam for precise alignment and angle measurements All angle measurements recorded for construction database Børge Svane Nielsen, NBI
Green laser assembly Green laser has been fitted with telescope to produce 20 mm beam was used for full length rod gluing and (with 90 prism) for installation of rods in FC should be used again to re-measure angles with horizontal TPC TPC end plate Børge Svane Nielsen, NBI
Laser rod installation Installation and re-measurements of all angles of central laser rays inside TPC field cage before strip mounting after strip mounting Green laser beam Børge Svane Nielsen, NBI
Spots measurements in TPC field cage After installation in the TPC, the central narrow laser beam spots were measured relative to the inner rods (dR=1.7 m). Measured before/after mounting of outer mylar strips. • Difference before/after strip • mounting: • large, systematic deviations • in z • - smaller deviations in Børge Svane Nielsen, NBI
Bending of rods Michi: bending of rod in the middle between supports due to strips: f (mm) = (Q L3) / (384 E J), J=π/64 ( D4 – d4 ) Original parameters (L=21 cm): f = 0.003 mm dZ (1.7m)=0.02 mm Half number of supports (L=42 cm): f = 0.047 mm dZ (1.7m)=0.38 mm Final macrolon tube dim. (L=42 cm): f = 0.079 mm dZ (1.7m)=0.64 mm Looks consistent with measurements of mirror bundle 2 and 3, but clearly much worse for mirror bundles 1 and 4 ( 5 mm) Børge Svane Nielsen, NBI
Status of quartz optics and mechanics • Quartz components (prisms, beam splitters, mirrors etc) for end-plates and laser hut received and tested needed coating re-work at factory: imminent re-delivery • Design progressing on opto-mechanical supports on end-plates Production of prism assemblies ongoing in NBI workshop Beam splitter holders bought and ready Beam splitter assembly Bending prism assembly Safety tube Børge Svane Nielsen, NBI
3d CAD drawings of full system on endplates CAD drawings transmitted to GSI Børge Svane Nielsen, NBI
Decision taken on beam height over endplates Beam moves ”up” (away from endplate) by 4 mm at each beam splitter (2 times) H Minimum beam height over endplate is H=90 mm, due to flanges with rods Laser tube must pass over TPC feet H 113 mm Chosen H = 113 mm height of top of last beam splitter box = 192 mm i.e. full height (200 mm) up to SSW needed at splitter (and prism) boxes; upper part of the tube is about 135 mm from endplates (65 mm ”left”) Need this info into CAD drawings at GSI Børge Svane Nielsen, NBI
Displacement of prism near TPC feet Agreement with Y.Andres to displace 2 prisms on each endcap, to avoid hitting the TPC ’feet’ Børge Svane Nielsen, NBI
DCS discussions DCS: • laser remote control: Spectron ’standard’ communication • 3-axis adjusters control: New Focus iPico system • cameras: USB web cameras (like ITS alignment) Collaboration with D. Beck (GSI) and M.Cherney (Creighton U): • looking into equipment sensitivity of magnetic field and radiation • drivers for laser and 3-axis adjusters to be written for PVSII • LabVIEW interface to USB cameras, with pictures and parameters • communicated to PVSII through DIM or shared files • Operator or automatic beam steering in PVSII script • Work has starting at GSI. Børge Svane Nielsen, NBI