1. LHCb support system upgrade
L. Leduc, J. Chauré, M. Gallilee, R. Veness
L. Leduc

2. OUTLINE Current layout
Material selection criteria – Optimization for transparency
New support system proposal
Testing
Safety
L. Leduc

3. CURRENT LAYOUT LhCb current layout: 8 stainless steel rods
8 stainless steel cables
2 aluminium collars
2 vespel rings
The support system is a source of background signal
Need to optimize -> the materials involved
-> the geometry
L. Leduc

4. Polymer based materials Carbon fiber reinforced epoxy λ= 230 mm
NEW MATERIALS
Criteria for selection:
1. Provide acceptable mechanical properties;
2. Reduce the traversed amount of matter
3. Improved radiation length
The radiation length λ of a material is the mean length (in cm) of matter over which a high energy electron has its energy reduced by the factor 1/e.
λ depends on both Z and A
Usually expressed in g/cm2 or cm
Metallic materials
Polymer based materials
Stainless steel λ= 17.6 mm
Titanium λ= 35.6 mm
Aluminum λ= 70 mm
Beryllium λ= 354 mm
Carbon fiber reinforced epoxy λ= 230 mm
Kevlar λ= 280 mm
Epoxy λ= 352 mm
L. Leduc

5. WIRE SYSTEM F Constraints on the design:
axial force F when the chamber is evacuated
stiffness : the axial displacement should be limited
-> axial stiffness should be high enough
Current solution:
8mm diameter stainless steel rods
3mm stainless steel wires F
L. Leduc

6. WIRE SYSTEM – SOLUTION N°1
Flexible cables replaced by Vectran/Technora ropes
Spliced eye close to the beampipe
Adjustable fitting at the magnet yoke
Technora repeating unit
[C14O2N2H10]m-[C20O3N2H14]n
Vectran repeating unit
[C7O20H4]m-[C11O2H6]n
Mechanical tests:
A. Gerardin
J. Chauré, M. Guinchard
L. Leduc

7. WIRE SYSTEM – SOLUTION N°1
Rigid rods replaced by carbon fiber reinforced epoxy tubes
M46J High Modulus fibers (Toray)
Lay up: [+-8°/90°/+-8°/+-8°/90°/+-8°]
Epoxy glue
Aluminum termination
Ansys simulations to optimize the joint strength
Currently under production Mateduc Composites
Will be glued to termination in CERN polymer lab
S. Clément
Will be tested in CERN mechanical lab
A. Gerardin
L. Leduc

8. WIRE SYSTEM – SOLUTION N°1
Indicator for transparency:
For the rope For the CFRP tube d d
d = 5 mm
ID = 14 mm
ID = 18 mm
d = 11.3 mm
→ I = d/λ
Low Value = Good
L. Leduc

9. WIRE SYSTEM – SOLUTION N°1
Performance of solution n°1
Radiation length λ (mm) I
Gain in transparency
Axial displacement (mm)
Stress safety factor
(termination)
Current supports
Rods
cables
17.6
0.45
0.17
1.2(S2F)/0.75(S3F)
New supports
CFRP tubes
ropes
230
>289
5e-2
<1.7e-2
89%
90%
1.4(S2F)/0.98(S3F)
2.9
3.8
→ Much lighter solution while keeping the acceptable mechanical properties
L. Leduc

10. WIRE SYSTEM-SOLUTION N°2 (BACKUP)
Solution n°2 is currently under investigations with LHCb
Selected material: Aluminium design λ=70mm
Rigid wire geometry (two possibilities):
A) Tube ID:14 mm, OD:20 mm
Rod diameter: 12 mm
Gain in transparency: 62%
B) Flat strip dimensions: thickness 8mm, length 18mm
Gain in transparency: 75%
→ The geometry in under assessment with LHCb
Flexible wire solution:
Rod diameter: 2 mm
Coupled in series with 20 cm stainless steel cable at the magnet yoke
Gain in transparency: 83%
The selected solution will be welded to its termination
L. Leduc

11. COLLAR/ATTACHMENT SYSTEM
Current solution
Aluminum 6082 T6
Aluminum attachment system
Stainless steel screws
Applied forces do not cross at the midplane
→ Moment induced on the beampipe
L. Leduc

12. COLLAR/ATTACHMENT SYSTEM
New solution
Material: Beryllium Instrument grade
The attachment system is integrated to the collar
No moment applied on the beampipe
Comparison of mechanical properties
Two geometries currently under assessment by LHCb for the physics point of view.
Strength (MPa)
Radiation length (mm)
Be I 220 FH
340
354
Al 6082 T6
240 70
L. Leduc

13. Under Assessment by LHCb
COLLAR/ATTACHMENT SYSTEM
Design work with J. Chauré
Solution n°1
Solution n°2
Collar based on F.Tarnowski preliminar work
Same attachment system than solution n°1
Thickness 2mm
Thickness of the ring 13 mm
Solution n°1 has 30 % less volume than solution n° 2
But solution n° 2 offers less material close to the beampipe
Under Assessment by LHCb
L. Leduc

14. COLLAR/ATTACHMENT SYSTEM
Mechanical performance of collar n° 2 without attachment system
Stress safety factor
Volume reduction
S2F collar
Current
Collar n°2
2.1
4.1
15.4%
S3F collar
2.5
22%
→ Much lighter solution while keeping the same mechanical efficiency
We expect the same trend with the integrated attachment system
Selected supplier
ExoTec Precision in Taunton, UK
Manufacture an aluminum prototype collar for tests
L. Leduc

15. INTERFACE RING Current solution:
Material : graphite reinforced Vespel (polyimide )
Aluminum ring for bake out
New solution
Material: Celazole [C20H12N4]
Could be used during bakeout
Comparison of material properties
Tensile strength
(MPa) at room temperature
Tensile Strength (MPa) at 250°C
Compression strength (MPa) at room temperature
Compression strength (MPa)
At 250 °C
Celazole
160
117
390
172
Vespel SP 21 66 38 ?
L. Leduc

16. INTERFACE RING Volume optimization
Reduced thickness of the ring -> volume reduction
Reduced number of fasteners
Material optimization
Currently stainless steel fasteners
New solution ->Titanium fasteners
Celazole is more transparent than Vespel
Volume Optimization
S2F
Fasteners
I Ring
75%
55%
S3F
62%
32%
Radiation length (mm)
Current support
Fasteners
I Ring
17.6
275
New supports
35.6
325
L. Leduc

17. Modified Von Mises stress after bakeout
INTERFACE RING
Two steps for calculation:
Step 1: steady state thermal analysis → Step 2 : static structural analysis
Modified Von Mises stress after bakeout
S3F support
Stress safety factor: 3
L. Leduc

18. TESTS Radiation testing organized by G. Spiezia (RP):
LHCb calculated dose over 20 running years: 2MGy
Materials: Celazole & Vectran, technora ropes
9 dose steps: 0-> 10 Mgy at dose rate of 70 kGy/h
one additional step at 1 kGy/h to 500kGy -> to assess dose rate effects
Required information: strength and stiffness
Fraunhoffer Institute in Germany -> September
Creep tests:
Synthetic ropes
CFRP tubes (glue)
Before and after bakeout (50°C)
Possibility of accelerating creep rate by increasing temperature -> life time
Independent Polymer Technology in England -> August (duration 1 month)
Assembly tests
Aluminum prototype for collar/attachment and interface ring
Mock up of the chamber
Wire system with a scale 1:3
L. Leduc

19. SAFETY ASPECTS
Ongoing discussion with J. Gulley, P. Silva and D.D Phan from safety
risk assessment of using → Beryllium collar/attachment system
→ Synthetic simple braid ropes
Use of Beryllium
write a procedure of the assembly
risk assessment (drop or scratch of the item, …)
procedure in case of hazards
ex: scratch of a piece
→ stop the handling
→ dismanteling
→ use of a glove box
Use of synthetic ropes
Safety team want to be present for the tests
Procedure and risk assessment in case of fire
L. Leduc

20. CONCLUSIONS ACKNOWLEDGEMENTS
The proposed system is lighter than the current one: from 90% (wire) to 65% (fasteners)
Safety is being carefully included in the design
Back up solutions are proposed, that are lighter than the current system
ACKNOWLEDGEMENTS
R. Veness, M. Gallilee, J. Chauré, G. Corti, M. Karacson, M. Guinchard, H. Rambeau, H. Kos, P. Coly, P. Lepeule, C. Loureaux, G. Foffano, S. Clément, G. Kirby, J. Gulley, P. Silva, D.D Phan, G. Spiezia.
L. Leduc