1. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand LHCb Vertex Detector System: Status Report J.F.J. van den Brand Subatomic Physics Group, VUA - NIKHEF Milan design Optimized design mechanics vacuum system cooling system Summary

2. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand Mechanics: “TP” design Side flange Bending hinges Detector support and cooling Bellows (22000 signal wires) Support frame Si detector moves by 30 mm only two positions: open or closed !! See LHCb 99-042/VELO top half = bottom half

3. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand Milan design VELO Design: Single flange XY table CO 2 cooling WF suppressors Second. vacuum Studied assembly alignment To do further design FEA

4. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand Detector and support frame both halves on same side VD easier to mount and position in the tank install complete VD at once the two halves are no longer interchangeable

5. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand Vacuum vessel Employ top flange Easier installation Shorter cables Length 2000 mm Width 1200 mm

6. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand Top flange 770 1900 Lift 600 Length 1500 mm Distance from ceiling 1900 mm Install using wires Baking to 60 o C? Regenerate NEGs after every access to Si detectors

7. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand Optimized System 1250 1820 2150 1450 Total length: 1750 Two detector boxes Baking up to 150 o C Decouple access to Si detectors

8. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand Support system bellows chain/belt cooling/bake out gearbox 1:40 ball spindle 16x2  5 mm linear bearing 2x 30 +5 motor Microswitches at out position LVDTs Steel frame Alignment: –2 planes –3 points each –define IP

9. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand Support system Alignment pins for reproducible coupling reproducible positioning

10. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand Vessel Installation Move bellows to in-position Install vessel from top Align vessel Mount vessel to frame Mount bellows Pump-outs visible

11. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand Install 2nd-Vacuum Vessel Remove upstream flange Need 2 m access Rectangular bellows –60 mm stroke –normal 35 mm –lateral 6 mm Fabrication –Palatine, Bird –Calorstat, MB –cost

12. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand Vacuum vessel / Positioning system Moving parts not in vacuum Thin vacuum container Special bellows construction Secundary vacuum Primary vacuum

13. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand After installation Detector system separated from vacuum system functionality Mount positioning system to detector housing Install –pump-out, valves –turbos, damping

14. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand Connect inner system to motion drives Mount M8 through side flanges

15. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand Detector Installation Install detector halfs from sides Decouple detectors from box Tooling needed

16. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand VELO Assembly Detectors mounted

17. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand Wakefield suppressors Mount screens after mounting 2nd vacuum container Mount through top flanges –seal with view ports? Upstream: mount with large flange off WF screens 420 910 IP

18. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand Wakefield suppressor: downstream Up/downstream suppressors are identical Material: CuBe Length: 179 mm Thickness: 100  m 16 segments Mounting to box non-trivial

19. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand Wakefield suppressors Segments deform differently during movement Coating needed on suppressors Press-fit to beam pipe structure Anneal CuBe, deform, harden at 400 o C

20. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand Detector Mounting Install Modules 3D alignment Mount References

21. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand Thin Vacuum foil Beryllium expensive: k$ 500 per container Aluminum –welding 250  m Al is possible –press-shaping being developed FEA ongoing

22. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand Thin Vacuum foil Labour intensive: press, anneal, etc. welding 250  m Al is possible Extensive prototyping program Chiel Bron CP?!

23. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand Thin Vacuum foil Increase radius: 10  20 mm to avoid folding Crystal structure is affected Employ Al with magnesium alloy Deform at higher temperature: 150 - 200 o C

24. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand Foil design ongoing (continued)

25. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand Foil design ongoing

26. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand Control of Vacuum System Group active with experience at former NIKHEF accelerator Propose meeting in Q1 2001

27. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand Vacuum Tests Self-regulating valve behaves as advertized Various gas flows have been characterized

28. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand Vacuum constraints LHC: beam life time: static density of 10 -7 mbar  2 m (H 2 300K)  0.01 % of LHC limit for integrated density ( 2.7 10 6 cm  1.6 10 9 molecules/cm 3 ) beam stability: dynamic effects must be taken into account LHCb: 10 -7 mbar  1.2 m (H 2 300K)  1.5 % of LHCb nominal luminosity Difficult to achieve with silicon detectors, electronics and signal wires directly in LHC vacuum !  differential pumping. (rough!) See LHCb 99-045/VELO

29. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand Static pressure in VD Consider outgassing by: assuming outgassing rates of: (mbar l s -1 cm -2 )  11 m 2 Kapton (signal wires, pumped 40 hours) 10 -7 H 2 O  2.3 m 2 Al housing (per half) 10 -10 H 2  1.5 m 2 bellows (per half) 10 -9 H 2  8 m 2 SS vessel10 -10 H 2 Pumps in detector volume:  140 l/s (per half) H 2 O Pumps in tank:  4000 l/s H 2 Bypass tube: 200 mm  4 mm pumped in the middle. Calculate using a static flow model. Result: 1 10 -4 mbar in detector volume 1 10 -8 mbar in VD tank 2 10 -8 mbar l s -1 from det. vol. to VD tank

30. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand S ummary table: (Data are approximate. Q LHCb_total = estimate for the full vertex detector, i.e. both halves.) Item Outgassing rate of itemQ LHCb_total [mbar l s -1 ] Kapton foil, after 40 hrs pumping 1 E-7 mbar l s -1 cm -2 n/a sample Kapton flat cable QPI 3 E-5 mbar l s -1 130 E-4 male/female pair of PEEK D-type 25-pin connectors6 E-6 mbar l s -1 / pair 50 E-4 male/female pair of stand. D-type 25-pin connectors1 E-5 mbar l s -1 / pair 100 E-4 Liverpool carbon-fiber Si support 1 E-8 mbar l s -1 cm -2 ~ 1 E-4 Outgassing measurements Continue: measure all unknown outgassing rates of components in a detector station

31. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand Dynamic Vacuum Beam-induced particle bombardment  desorption, emission Ions, photons, electrons energies up to keV Local pressure runaway (ion/electron-induced desorption) Local static charge increase (electron multipacting) LHC beam instability See Adriana Rossi’s presentation

32. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand Dynamic Vacuum (continued) Perhaps a solution: use coating of surfaces by Ti advantages: low  SEY, low , local pumping Design issues: better surfaces ? (NEG ?) in-situ coating required or not ? thickness of layer needed ? what re-coating rate ? affordable cathode temperature in-situ ? wake field / RF properties ? side effects ? (peeling,...) We need ,  for: different materials surface conditions (un)baked, saturated, activated, etc. different impact energy spectra Data available only in a few months ! (Mahner et al.)

33. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand Cooling system with mixed-phase CO 2 *

34. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand CO 2 Cooling Tests Cooling system -30 o C 40 W/module

35. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand CO 2 gas-liquid storage tank 57.3 bar at 20  C CO 2 supply line compresssor P [W] flow restrictions cooling lines gas only pressure (temperature) regulating valve heat to 20  C Mixed-phase CO 2 Cooling system See LHCb 99-046/VELO cool to 20  C supply line expansion valve

36. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand CO 2 Cooling Tubes Cooling tubes 1.1 (0.9) mm S.St. Welding and brazing

37. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand FEA ongoing

38. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand Tests ongoing

39. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand RF tests at NIKHEF Simulation with MAFIA First 3 measured eigenmodes: 220 MHz 270 MHz 380 MHz Outlook: Eigenmodes Short range effects; Z/n Electric field inside secondary vacuum Picture 1 of tank removed Picture 2 of tank removed

40. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand Wake field Suppressor Central cooling line Temperature sensors (2 per station, 4 wires per measurement

41. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand Detector Modules Number of planes: 25 Discuss Liverpool delivers modules 40 W, 1 m cable, 50 % isolation thickness, 10 - 15 K  T, radiative cooling 44 pins, 440 / module

42. vrije Universiteit amsterdam CERN, November 27, 2000 VELO System J.F.J. van den Brand Summary Design is based on secondary vacuum system –Beryllium option: costly and uncertain –needs approval for TDR Current design –allows baking up to 150 o C –decouples Si detectors from primary vacuum system –employs venting with Argon –cooling based on CO 2 in gas-liquid phase Self-regulating valves behave as advertised Wakefield excitation under study Need information on dynamic vacuum effects Propose meeting on control issues (e.g. NIKHEF)