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Mechanical structure of SVD2

Mechanical structure of SVD2. Y.Yamada (KEK) at SVD internal review on Feb. 2nd, 2001 http://yamadapc1.kek.jp/~yamaday/BELLE/SVD2/doc/svdreview_010202. Detector layout Mechanical structure end ring, outer cover and support cylinder Assembly procedure Support structure on CDC

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Mechanical structure of SVD2

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  1. Mechanical structure of SVD2 Y.Yamada (KEK) at SVD internal review on Feb. 2nd, 2001 http://yamadapc1.kek.jp/~yamaday/BELLE/SVD2/doc/svdreview_010202 • Detector layout • Mechanical structure • end ring, outer cover and support cylinder • Assembly procedure • Support structure on CDC • Man power and Schedule

  2. Detector layout (Radii are 30, 45 and 60 mm in SVD1.)

  3. Inner radius • Number of layers depends on beampipe radius • Routbp = Rinbp + dRbp(=1.5 mm ) • dRbp = 0.5 mm (inner Be) + 0.5 mm (PF200) + 0.25 mm(outer Be) + 0.25 mm (gold) • RinSVD = Routbp+1 mm (11 mrad tilting) + 1 mm (production tolerance) + 1 mm (gap) • R1st layerSVD < 15 mm for no dead region in   • Rinbp < 10.5 mm : five layers • Rinbp > 10.5 mm : four layers

  4. Outer radius • CDC : cathode part  small cell chamber • CDC inner radius : R = 77 mm  102 mm • SVD • outer cover : • R = 75 mm  100 mm • outermost layer : • R = 60 mm  90 mm

  5. Design features • Same concept with SVD1 • end rings for ladders • outer cover and support cylinder for main structure • clam shell division at assembly with beam pipe • New features • Full acceptance of BELLE : 17º < q < 150º (23º < q < 140º in SVD1) • not straight ladder using flex circuit • super-layer structure for first and second layer in five layer design • CFRP for end ring • DSSD is cooled down to 15 degree C • no inner cover • replaceable inner end ring • more number of ladders : 32 (SVD1)  60(SVD2 5 layer) • longer ladder : 37cm (SVD1 3rd layer)  65 cm (SVD2 5th layer) • Minimum number of variations on ladder parts • three (narrow, normal and wide) DSSDs, two (normal and wide) hybrids, • narrow one-DSSD half ladders for 1st layer, • normal one-DSSD, two-DSSD and three-DSSD half ladders for 2nd/3rd/4th layer, • wide three-DSSD half ladders for for 5th layer

  6. Mechanical structure of SVD2 • Four or Five layers of DSSD ladders are supported by the end rings • which is made of Aluminum and CFRP, • Forward and backward end rings are connected by the outer cover • which is made of 0.5mm-t CFRP, • end rings and outer cover are supported by forward and backward • support cylinders which is made of 2.5mm-t CFRP, • support cylindersare supported by the end plates of CDC.

  7. Structure of SVD1 DSSD ladder end ring outer cover beam pipe support cylinder

  8. Outer cover and support cylinder stiff cylinder : EI = 1 x 104 Nm2 SVD1 outer cover (R=7.5cm, 1.5 mm-t) support cylinder (2.5mm-t) • CFRP • Mitsubishi-chemical Co. • E = 200 GPa • CTE = 1x10-6 m/m/°K • 220 W/m/°K SVD1 SVD1

  9. FEM analysis (SVD1) Gravitational sag is ~ 6 microns

  10. End ring • Backward end ring • inner ring for 2nd layer • outer rings for 3rd/4th/5th layer • Forward end ring • inner ring for 1st/2nd super-layer • outer rings for 3rd/4th/5th layer

  11. Forward end rings • outer ring • Al ring • for 3rd/4th/5th layer • CFRP cone • Flange for support • cooling tube • inner ring • Al ring for • 1st/2nd super-layer • (or 2nd layer) • CFRP cone • Flange for support • cooling tube

  12. Forward end rings super layer for 1st/2nd layer 3rd layer 4th layer 5th layer

  13. Backward end rings 5th layer 4th layer 3rd layer 2nd layer

  14. Support flange (forward) CDC endplate side end ring side

  15. Thermal property • At start of operation (or a experiment) • Si DSSD : 0.65 m  3 ppm/°   10 ° ~ 20 mm • CFRP Outer cover : 0.7 m  1 ppm/°   15 ° ~ +10 mm • Al end ring : 0.02 m  24 ppm/°   15 ° ~  7 mm •  should be absorbed by sliding mechanism of ladder Temperature control system during operation was installed last summer. temperature of heat sink Before control : ±3.5° after control : ±1.0° •  No deformation • in a experiment time (hours)

  16. Ladder support scheme • ladder (hybrid) is fixed on end ring surfaces • fixed rigidly on backward end ring • fixed on forward end ring with sliding mechanism • using precisely (±10 mm) machined pins and holes 2.0 mm- pin in 3.5 mm- hole in heatsink with special spring 3.5 mm- pin in 3.5 mm- hole in heatsink

  17. ladder support in SVD1 • backward hybrid is aligned by • 5 mm brass pin • 5 mm hole in heatsink • 5 mm hole in end ring. 5 mm pin 5 mm hole SVD1 5 mm hole SVD1 • Forward hybrid is aligned by • 3 mm brass pin • 5 mm hole in heatsink with special spring • 3 mm hole in end ring •  allow sliding of ladder • in Z without R-f motion M3 screw with gull wing spring for fixing hybrid 3 mm pin 3 mm hole 5 mm hole with special spring SVD1 SVD1

  18. Property of ladder sliding (SVD1) • If we push ladder from backward side • sliding occurs around D=20 microns • (or dT=10 °C or f=7kgf). • bowing of ladder is 10 microns • at maximum with the ribs of BN • (1mm thick and 7mm high).

  19. Backward hybrid • backward hybrid is aligned by • 3.5 mm brass pin • 3.5 mm hole in heatsink • 3.5 mm hole in end ring. heatsink M3 screw with gull wing spring for fixing hybrid 3.5 mm diameter brass pin in 3.5 mm hole in end ring and heatsink

  20. Forward hybrid • Forward hybrid is aligned by • 2 mm brass pin • 3.5 mm hole in heatsink with special spring • 2 mm hole in end ring •  allow sliding of ladder in Z direction without R-f motion heatsink M3 screw with gull wing spring for fixing hybrid 2 mm diameter brass pin in 2 mm hole in end ring and 3.5 mm hole in heatsink

  21. Assembly procedure • Machining end rings on jig using NC machine • Mounting ladders on end rings • Dividing into two clam shells • Assemble inner and outer end rings with support flange • Assemble two clam shells with support cylinders • and beam pipe

  22. machining of end ring SVD1 1/8 inch Cu tube is glued on end ring with silver epoxy. SVD1 Forward/backward end rings are machined on the jig simultaneously to keep forward/backward surfaces parallel. Accuracy is 10 ~ 20 microns.

  23. mounting ladders SVD1 SVD1 End ring with ladder mount jig on assembly bench SVD1

  24. Final assembly SVD1 SVD1 attach outer covers with temp. supports assemble with support cylinder/beampipe SVD1 SVD1 division into two clam shells

  25. Support structure on CDC SVD is supported at three points on forward/backward flange of CDC independently from heavy beam pipe. · · · diaphragm which allows Z motion only backward forward

  26. Recent modification change of connector on hybrid due to increase of lines (34  51) • thickness increased(1.0  3.2) mm  5 layers = 11 mm •  large modification of structure required (not yet done)

  27. Task list in near future • modification due to change of connector (one month) • confirmation of interferences using 3D-CAD • simulation on strength and temperature • prototyping ladders and support structure (three months) • design of support mechanism on CDC including beam pipe • design of assembly tools • .....

  28. Man power and schedule • Design, drawing and assembly : • KEK(Y.Yamada, J.Suzuki, S.Koike, A.Satpathy and others) • Machining : • KEK machine shop and others • Measurement and installation : • KEK, Niigata, Tokyo, Osaka, TIT, NTU and others • Temporary schedule for installation in Aug. 2002 • Prototyping by spring 2001 • Final drawing by summer 2001 • Machining by end of 2001 • Ladder mounting by early 2002 • Final assembly by spring 2002

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