new materials for lhcb support systems l. leduc, j. chauré , g. corti, m. gallilee, r. veness

CERNEUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH

Louise Leduc 114 October 2011

New materials for LHCb support systemsL. Leduc, J. Chauré, G. Corti, M. Gallilee, R. Veness



1. Current layout

2. Material selection criteria – Optimization for transparency

3. New support system proposal

4. Testing

5. Safety

OUTLINE



CURRENT LAYOUT

The support system is a source of background signalNeed to optimize -> the materials involved

-> the geometry

LhCb current layout:• 8 stainless steel rods• 8 stainless steel cables• 2 aluminium collars• 2 vespel rings



NEW MATERIALSCriteria for selection:

1. Provide acceptable mechanical properties;

2. Reduce the traversed amount of matter

3. Improved radiation lengthThe 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 AUsually expressed in g/cm2 or cm

Metallic materials Polymer based materials

Stainless steel λ= 17.6 mmTitanium λ= 35.6 mmAluminum λ= 70 mmBeryllium λ= 354 mm

Carbon fiber reinforced epoxy λ= 230 mmKevlar λ= 280 mmEpoxy λ= 352 mm



Constraints on the design: axial force F when the chamber is evacuatedstiffness : the axial displacement should be limited-> axial stiffness should be high enough

Current solution: 8mm diameter stainless steel rods3mm stainless steel wires

WIRE SYSTEM

F



Flexible cables replaced by Vectran/Technora ropes

WIRE SYSTEM – SOLUTION N°1

Spliced eye and vespel ring termination

Vectran repeating unit[C7O20H4]m-[C11O2H6]n

Technora repeating unit[C14O2N2H10]m-[C20O3N2H14]n

Rigid rods replaced by carbon fiber reinforced epoxy tubesM46J High Modulus fibers (Toray)Lay up: [+-8°/90°/+-8°/+-8°/90°/+-8°]Gluing to aluminium termination with aralditeProduced by Mateduc CompositesGluing to termination in CERN polymer lab: S. ClémentTesting in CERN mechanical lab : A. Gerardin



Selected material: Aluminium design λ=70mm

Rigid wire geometry :Tube ID:15 mm, OD:20 mm

Flexible wire solution:Tube ID:3 mm, OD:8 mm

The solution will be screwed to termination

WIRE SYSTEM-SOLUTION N°2 (BACKUP)



TRANSPARENCY

Indicator for transparency:

For the rope/rod 5 mm diameter

y

Caracteristic length

Indicator of transparency I=d/λ

dxlRdR

x0./1

xlx

0 R



TRANSPARENCY

Indicator for transparency:

For a tube ID= 14 mm; OD=18 mm

Caracteristic length

Indicator of transparency I=d/λ

dxlRdR

x0./1

xlx

0 R

y



COMPARISON OF SOLUTIONS

Radiation length λ (mm)

Caracteristic length d (mm)

I Gain in transparency

Stress safety factor

(termination)

Current supports- Rods- cables

17.66.32.3

0.360.13

Solution 1- CFRP tubes- ropes

230>289

5.62.9

2.4e-2<1.3e-2

93%90%

2.9>>

Solution 2- Aluminum tubes- Aluminum tubes

7070

6.95.4

9.8e-27.7e-2

73%40%

2.42.0

→ Much lighter solutions while keeping acceptable mechanical properties

Performance of both solutions



Current solution:Material : graphite reinforced Vespel (polyimide )Aluminum ring for bake out

New solutionMaterial: Celazole [C20H12N4]Could be used during bakeout

Comparison of material properties

INTERFACE RING

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 172Vespel SP 21 66 38



Volume optimizationReduced thickness of the ringReduced number of fasteners

Material optimization Currently stainless steel fasteners New solution ->Titanium fastenersCelazole is more transparent than Vespel

INTERFACE RING

Volume OptimizationS2F Fasteners I Ring

75%55%

S3F Fasteners I Ring

62%32%

Radiation length (mm)Current support Fasteners I Ring

17.6275

New supports Fasteners I Ring

35.6325



Radiation testing organized by G. Spiezia (RP):LHCb calculated dose over 20 running years: 2MGyMaterials: Celazole & Vectran, technora ropes9 dose steps: 0-> 10 Mgy at dose rate of 70 kGy/hone additional step at 1 kGy/h to 500kGy -> to assess dose rate effectsRequired information: strength and stiffnessFraunhoffer Institute in Germany -> October

Creep tests:Synthetic ropesCFRP tubes (glue)Before and after bakeout (50°C)Possibility of accelerating creep rate by increasing temperature -> life timeMECASEM SA in France

Assembly testsAluminum prototype for collar/attachment and interface ringMock up of the chamberWire system with a scale 1:3

TESTS



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 Berylliumwrite a procedure of the assemblyrisk 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 ropesSafety team want to be present for the testsProcedure and risk assessment in case of fire

SAFETY ASPECTS



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

CONCLUSIONS

ACKNOWLEDGEMENTS

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.

new materials for lhcb support systems l. leduc, j. chauré , g. corti, m. gallilee, r. veness

Documents

nuclear research louise

current solution

flexible wire solution

mean length

materialsstainless steel

tube id

aluminium termination

aluminium design