1. CERN EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH Louise Leduc1 14 October 2011 New materials for LHCb support systems L. Leduc, J. Chauré, G. Corti, M. Gallilee, R. Veness

2. CERN EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH Louise Leduc2 14 October 2011 1.Current layout 2.Material selection criteria – Optimization for transparency 3.New support system proposal 4.Testing 5.Safety OUTLINE

3. CERN EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH Louise Leduc3 14 October 2011 CURRENT LAYOUT The support system is a source of background signal Need to optimize -> the materials involved -> the geometry LhCb current layout: 8 stainless steel rods 8 stainless steel cables 2 aluminium collars 2 vespel rings

4. CERN EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH Louise Leduc4 14 October 2011 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/cm 2 or cm Metallic materialsPolymer 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

5. CERN EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH Louise Leduc5 14 October 2011 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 WIRE SYSTEM F

6. CERN EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH Louise Leduc6 14 October 2011 Flexible cables replaced by Vectran/Technora ropes WIRE SYSTEM – SOLUTION N°1 Spliced eye and vespel ring termination Vectran repeating unit [C 7 O 20 H 4 ] m -[C 11 O 2 H 6 ] n Technora repeating unit [C 14 O 2 N 2 H 10 ] m -[C 20 O 3 N 2 H 14 ] n Rigid rods replaced by carbon fiber reinforced epoxy tubes M46J High Modulus fibers (Toray) Lay up: [+-8°/90°/+-8°/+-8°/90°/+-8°] Gluing to aluminium termination with araldite Produced by Mateduc Composites Gluing to termination in CERN polymer lab: S. Clément Testing in CERN mechanical lab : A. Gerardin

7. CERN EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH Louise Leduc7 14 October 2011 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)

8. CERN EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH Louise Leduc8 14 October 2011 TRANSPARENCY Indicator for transparency: For the rope/rod 5 mm diameter y Caracteristic length Indicator of transparency I=d/λ x lxlx 0 R

9. CERN EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH Louise Leduc9 14 October 2011 TRANSPARENCY Indicator for transparency: For a tube ID= 14 mm; OD=18 mm Caracteristic length Indicator of transparency I=d/λ x lxlx 0 R y

10. CERN EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH Louise Leduc10 14 October 2011 COMPARISON OF SOLUTIONS Radiation length λ (mm) Caracteristic length d (mm) IGain in transparency Stress safety factor (termination) Current supports - Rods - cables 17.6 6.3 2.3 0.36 0.13 Solution 1 - CFRP tubes - ropes 230 >289 5.6 2.9 2.4e-2 <1.3e-2 93% 90% 2.9 >> Solution 2 - Aluminum tubes 70 6.9 5.4 9.8e-2 7.7e-2 73% 40% 2.4 2.0 → Much lighter solutions while keeping acceptable mechanical properties Performance of both solutions

11. CERN EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH Louise Leduc11 14 October 2011 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 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 Celazole160117390172 Vespel SP 216638

12. CERN EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH Louise Leduc12 14 October 2011 Volume optimization Reduced thickness of the ring Reduced number of fasteners Material optimization Currently stainless steel fasteners New solution ->Titanium fasteners Celazole is more transparent than Vespel INTERFACE RING Volume Optimization S2F Fasteners I Ring 75% 55% S3F Fasteners I Ring 62% 32% Radiation length (mm) Current support Fasteners I Ring 17.6 275 New supports Fasteners I Ring 35.6 325

13. CERN EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH Louise Leduc13 14 October 2011 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 -> October Creep tests: Synthetic ropes CFRP tubes (glue) Before and after bakeout (50°C) Possibility of accelerating creep rate by increasing temperature -> life time MECASEM SA in France Assembly tests Aluminum prototype for collar/attachment and interface ring Mock up of the chamber Wire system with a scale 1:3 TESTS

14. CERN EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH Louise Leduc14 14 October 2011 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 SAFETY ASPECTS

15. CERN EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH Louise Leduc15 14 October 2011 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.