Vrije Universiteit amsterdam Milan, September 25, 2000 VELO System J.F.J. van den Brand LHCb Vertex Detector System: Status Report J.F.J. van den Brand

vrije Universiteit amsterdam Milan, September 25, 2000 VELO System J.F.J. van den Brand

LHCb Vertex Detector System:Status Report

J.F.J. van den BrandSubatomic Physics Group, VUA - NIKHEF

• Review of TP design mechanics, vacuum system, cooling system.

• Requirements more cooling power,

intermediate Y positions of two halves

• Milestones


Mechanics: “TP” design

Side flange

Bending hinges

Detector support and cooling

Bellows (22000signal wires)

Support frame

Si detector

moves by 30 mmonly two positions:open or closed !!

See LHCb 99-042/VELO

top half = bottom half


Requirements on VD designVELO workshop in Amsterdam (April ‘00):

• Top/bottom halves should have intermediate steps (not only open/closed), with `relaxed’ overall position accuracy (0.3 mm). Only useful if we can acquire meaningful data in intermediate positions ! trigger algorithm

• Higher cooling power required (20 W/module 40 W/module) to accommodate for backup solution SCTA/velo. Should be no problem for CO2 cooling system, but is it realistic at all ?

thermal modeling needed


Modified design

VELO Design:

• Single flange • XY table•CO2 cooling•WF suppressors•Second. vacuum•Studied

• assembly• alignment

•To do• further design• FEA


Vacuum tank• new FEA required (probably additional ribs are needed)• flange will be on inside of LHC ring • solves lack of space issue on outside of ring• all feedthroughs on the same big flange • all cables and repeater cards on same side (present choice of feedthrough limits total number of pins to about 25,000 !!)


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


Detector Mounting

Install Modules

3D alignment

Mount References


Wake field Suppressor

Central cooling line

Temperature sensors (2 per station, 4 wires per measurement


Wake field Suppressor

Welding tests: 250 m Al

FEA: Beryllium


Foil design options (continued)






CO2 Cooling Tubes

Cooling tubes

1.1 (0.9) mm S.St.

Welding and brazing


CO2 Cooling Tests

Cooling system

-30o C

40 W/module


Detector Assembly

• External reference marks• Wires fed through 7 bellows• Structure connects to frame


Support frames• No more problems of bending: stiff, stable structure• XY-table can move down enough to allow insertion of complete detector (tilting mechanism no longer needed)• frames not any longer `in our way’ (more accessibility to critical items of VD)


Support frames

• FEA studies ongoing• Connect to outside• Allows vacuum tests


Support frames

• How to mount?• How to align?• Vacuum testing?• Cabling?• Rigidity?


Support frames

• Wake field screens• 3-point support• Alignment• XY table

• 5 mm, - 25 mm• Reset switches• LVDTs• Step motors


Support frames

•S.St. vacuum vessel•Exit foil by CERN

• RICH conflict?• Mounting RF shield?• Coating - Au, ..• z = 970 mm

• Acceptance• 300 mrad (hor.)• 250 mrad (vert.)• from IP• zero bunchlength


Support frames

• Steel frame• Fill with sand• Dimensions

• 1630 mm• 1500 mm• 1200 mm

• Align frame within 1 - 2 mm• Fix frame


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


Vacuum Tests


Vacuum Tests


TP design

center frame

New design

Sideways accessibility (1)

Side wake field suppressors

Ti evaporatorNo room onthe sides !


Sideways accessibility (2)• More access to critical WF suppressor• Much room left on one side of the tank 2ary vacuum pumps (pumping on the detector boxes is more efficient) if required, a Ti eva- porator with much more favorable design conditions


Cooling system with mixed-phase CO2

Phase diagram CO2

1

10

100

-80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50

Temperature [°C]

Pre

ssur

e [b

ar]

vapor

liquidsolidgas

critical point

triple point

*

Documents

Vrije Universiteit amsterdam Milan, September 25, 2000 VELO System J.F.J. van den Brand LHCb Vertex Detector System: Status Report J.F.J. van den Brand