LHCb support system upgrade L. Leduc, J. Chauré, M. Gallilee, R. Veness 24-06-2011 L. Leduc

OUTLINE Current layout Material selection criteria – Optimization for transparency New support system proposal Testing Safety 24-06-2011 L. Leduc

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 24-06-2011 L. Leduc

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 24-06-2011 L. Leduc

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 24-06-2011 L. Leduc

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 24-06-2011 L. Leduc

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 24-06-2011 L. Leduc

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 24-06-2011 L. Leduc

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 24-06-2011 L. Leduc

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 24-06-2011 L. Leduc

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 24-06-2011 L. Leduc

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 24-06-2011 L. Leduc

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 24-06-2011 L. Leduc

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 24-06-2011 L. Leduc

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 ? 24-06-2011 L. Leduc

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 24-06-2011 L. Leduc

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 24-06-2011 L. Leduc

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 24-06-2011 L. Leduc

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 24-06-2011 L. Leduc

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. 24-06-2011 L. Leduc