TPC meeting, Sardinia, 16-17 May 2004 Børge Svane Nielsen, NBI 1

Status of laser systemStatus of laser system

TPC meeting, Sardinia, 16-17 May 2004Børge Svane Nielsen

Niels Bohr Institute

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, NBI 2

Laser system principleLaser system principle

TPC meeting, Sardinia, 16-17 May 2004 Børge Svane Nielsen, NBI 3

Rod gluing and installationRod gluing and installation

1. Drill holes in short rods: done2. Mount mirror bundles in support rings: done3. Glue mirror support rings onto short rods: done4. Glue short rods into full length rods at CERN. done Scheduled to commence 20 October. alignment fixed during gluing, using green laser

5. Angle measurements on final rod possible in lab at CERN before installation, using same green laser done

6. Angle measurements possible again during rod installation in field cage, using same green laser done

7. Re-measurements with TPC in final orientation

TPC meeting, Sardinia, 16-17 May 2004 Børge Svane Nielsen, NBI 4

Full length rod gluingFull length rod gluing

All angle measurements recorded for construction database

Rods with pre-mounted laser mirrors were glued to full length TPC rods, usinggreen laser fitted with telescope to produce 20 mm beamfor precise alignment and angle measurements

TPC meeting, Sardinia, 16-17 May 2004 Børge Svane Nielsen, NBI 5

Green laser assemblyGreen 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

TPCend plate

TPC meeting, Sardinia, 16-17 May 2004 Børge Svane Nielsen, NBI 6

Laser rod installationLaser rod installationInstallation and re-measurements of all angles of central laser rays inside TPC field cage

before strip mounting

after strip mounting

Green laser beam

TPC meeting, Sardinia, 16-17 May 2004 Børge Svane Nielsen, NBI 7

Spots measurements in TPC field cage

Spots measurements in TPC field cage

Spot z movement due to strips

-6.0

-4.0

-2.0

0.0

2.0

4.0

6.0

8.0

1 5 9 13 17 21 25 29 33 37 41 45

Spot number (4 spots per rod)

Mo

vem

ent

(mm

)Spot Phi movement due to strips

-3.0

-2.0

-1.0

0.0

1.0

2.0

3.0

1 5 9 13 17 21 25 29 33 37 41 45

Spot number (4 spots per rod)

Mo

vem

ent

(mm

)

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 mountingof outer mylar strips.

Difference before/after stripmounting:- large, systematic deviations in z- smaller deviations in

TPC meeting, Sardinia, 16-17 May 2004 Børge Svane Nielsen, NBI 8

Bending of rodsBending 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 mmHalf number of supports (L=42 cm): f = 0.047 mm dZ (1.7m)=0.38 mmFinal 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)

TPC meeting, Sardinia, 16-17 May 2004 Børge Svane Nielsen, NBI 9

Status of quartz optics and mechanics

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 assemblyBending prism assembly

Safety tube

TPC meeting, Sardinia, 16-17 May 2004 Børge Svane Nielsen, NBI 10

3d CAD drawings of full system on endplates

3d CAD drawings of full system on endplates

CAD drawings transmitted to GSI

TPC meeting, Sardinia, 16-17 May 2004 Børge Svane Nielsen, NBI 11

TPC meeting, Sardinia, 16-17 May 2004 Børge Svane Nielsen, NBI 12

TPC meeting, Sardinia, 16-17 May 2004 Børge Svane Nielsen, NBI 13

Decision taken on beam height over endplates

Decision taken on beam height over endplates

Beam moves ”up” (away from endplate)by 4 mm at each beam splitter (2 times)

Minimum beam height over endplate is H=90 mm, due to flanges with rodsLaser tube must pass over TPC feet H 113 mm Chosen H = 113 mm height of top of last beam splitter box = 192 mmi.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

H

TPC meeting, Sardinia, 16-17 May 2004 Børge Svane Nielsen, NBI 14

Displacement of prism near TPC feet

Displacement of prism near TPC feet

Agreement with Y.Andres to displace2 prisms on each endcap, to avoid hittingthe TPC ’feet’

TPC meeting, Sardinia, 16-17 May 2004 Børge Svane Nielsen, NBI 15

DCS discussionsDCS 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.