Introduction Stability of cryodipole geometry at warm During Cool down measurements in SM18

1. MARIC – 28th April 2004First experimental results on stability of cryodipoles with central support post blocked Introduction Stability of cryodipole geometry at warm During Cool down measurements in SM18 Conclusion By Fabien Seyvet, AT-CRI

2. Introduction • Reminder: Conclusion of the workshop of the 16th of March 2004 on LHC dipole geometry and stability [1] • Central foot blockage is implemented unless showstopper • Validation on 10 magnets via additional measurements • Geometry measurement during cold tests • First experimental results on cryodipoles with central foot blocked will be presented • At warm • During SM18 cold tests MARIC, 28th of April 2004, First experimental results on stability of cryodipoles with central support post blocked, by Fabien Seyvet

3. Initial proposed plan and validation status PROCESS STATUS Total of 38 Cryodipoles blocked at WP02 (cryost.) 17 cryodip. for validation 10 Cryodipole done, incl5 for validation (w. WP03) 2 transported and re-fidu. • PROPOSED PLAN [1] • For at least 10 validation magnets • Evaluation of stability for MD • Central foot blocked • Central foot not blocked • And comparison on the basis of several definite geometry criteria, at each step in the production process ITP20 industry meas. CM transport Wp01 geometry meas. Cryostating Wp03 fiducialisation Blocking Cold test SM18 Wp08 fiducialisation Cryodipole transport-> SMi2 Wp08b fiducialisation Tunnel Note: approx 30 unplanned Fidus done by team of Dominique M. MARIC, 28th of April 2004, First experimental results on stability of cryodipoles with central support post blocked, by Fabien Seyvet

4. Number of magnets Not Blocked, 30 magnets 4 Blocked, 5 magnets 3 2 1 -1 0 1 2 (dS) : Difference in sagitta between entry into cold tests (WP03) and after cold tests (WP08) (absolute value) [mm] Stability study using sagitta Sagitta variations before and after COLD TESTS *1 choice and definition of parameters agreed within team *2 Work presented is a courtesy of Elena W. et al. [2] MARIC, 28th of April 2004, First experimental results on stability of cryodipoles with central support post blocked, by Fabien Seyvet

5. Number of magnets Not Blocked, 16 magnets 4 3 2 Blocked, 2 magnets 1 (dS) :Difference in sagitta between fidu after cold tests (WP08) and arrival in SMi2 (WP08b) (absolute value) [mm] -1 0 1 2 Stability study using sagitta Sagittavariations before and after TRANSPORT*1 *2 MARIC, 28th of April 2004, First experimental results on stability of cryodipoles with central support post blocked, by Fabien Seyvet

6. Not blocked, 16 magnets Not blocked, 31 magnets 0.6 0.5 AVG and 1σof the max. difference between 2 steps (mm) 0.4 Blocked, 2 magnets *3 σ stat. made on 4 aper.will improved with time 0.3 Blocked, 5 magnets 0.2 0.1 Effect of TRANSPORT WP8 → WP8b Effect of COLD TESTS WP3→ WP8 - 0.1 Stability study using max difference Maximum difference between CM shapes (10th order poly fit, support posts superposed) *1 *2 MARIC, 28th of April 2004, First experimental results on stability of cryodipoles with central support post blocked, by Fabien Seyvet

7. Not blocked, 16 magnets 0.5 Not blocked, 31 magnets 0.4 AVG and 1σof the CM ext. displ. between 2 steps (mm) 0.3 Blocked, 5 magnets 0.2 Blocked, 2 magnets *3 0.1 Effect of TRANSPORT WP8 → WP8b Effect of COLD TESTS WP3→ WP8 - 0.1 Stability study of CM extremity wrt cryostat CM extremity displacements wrt cryostat fiducials (average of Lyra and Conn side) MARIC, 28th of April 2004, First experimental results on stability of cryodipoles with central support post blocked, by Fabien Seyvet

8. Stability study conclusions • Stability seems improved with central support blocked • Validation is not complete yet, more magnets will enable more precise statistics & Validation team is preparing a joint project note on subject MARIC, 28th of April 2004, First experimental results on stability of cryodipoles with central support post blocked, by Fabien Seyvet

9. CFB Vacuum Window MOLE Vacuum MRB Ref Quad 1 Ref Quad 2 FID M Vacuum Pump Top view Leica 1 Leica 2 Cool down measurement set-up in SM18 • Cryostat fiducials relative displacements (Leica measurement only) • Leica and magnetic measurement, with a MOLE [3] MARIC, 28th of April 2004, First experimental results on stability of cryodipoles with central support post blocked, by Fabien Seyvet

10. Cryostat fiducial M (middle) horizontal relative displacement during cool down MARIC, 28th of April 2004, First experimental results on stability of cryodipoles with central support post blocked, by Fabien Seyvet

11. MOLE measurement during cool down MARIC, 28th of April 2004, First experimental results on stability of cryodipoles with central support post blocked, by Fabien Seyvet

12. Stability of geometry – Cool down measurements in SM18 • Conclusion of cool down measurement done in SM18 • Center of cryostat moves horizontally by approx. 0.8 mm. This corresponds to an equivalent transient lateralforce on the cryostat of 21.2 kN on the central support (assumption of a simply supported beam).NOTE: In the machine, cool down is much slower. Less transient deformation expected. • Cold and warm magnetic axis measurement (done including reference quadrupoles) are encouraging, further in details investigation on the data is required AND already on-going . MARIC, 28th of April 2004, First experimental results on stability of cryodipoles with central support post blocked, by Fabien Seyvet

13. Loads on support posts • Maximum admissible permanent forces applied onto support posts [4] • Combined loading TESTED: 92kN axial comp. and 25kN guided shear (creep validated)Probably conservative • Maximum admissible transient forces applied onto support posts [4] • Pure loads TESTED: 175 kN compression OR 40 kN cantilever bending – Probably conservative (production serie control tests) OR 40 kN guided bending • One case tested at 92 kN axial comp. and 70 kN (guided bending) with no macroscopic permanent damage and no stiffness change [5] • Worst load case under operating conditions : • Adjustment to itp20 (conservative compared to blocking in place w/o CM deform.). Assuming 1.5 mm max, F=8.8 kN • Operating conditions loads: 92kN Axial comp. + <5 kN lat. Shear (interconnection loads) • TOTAL: 92 kN axial comp. + <13.8 kN lat. shear • Worst load case during transitory cool down in SM18 • One cryodipole measurement : Cryostat center moves approx. by 0.8 mm horizontally. Simply supported beam theory leads to a force of 21.2 kN. • Adjustment to itp 20, F=8.8 kN not included (done in SMI2 only) • TOTAL = 92 kN axial comp. + 21.2 kN laterally MARIC, 28th of April 2004, First experimental results on stability of cryodipoles with central support post blocked, by Fabien Seyvet

14. Support post loadingpreliminary conclusion c) Worst load case during transport • M. La China [6] suggests 35.7 kN laterally NOTE: 54 kN instead on ext. posts if central foot not blocked for 0.3 g centripetal accel. ! • Initial loading (adjustment to itp20) = 8.8 kN • TOTAL = 92 kN axial comp. + 44.5 kN laterally • CONCLUSION • Additional cool down measurement is required to quantify more statistically the force on the central support post AND further testing of the support will then be required with the corresponding load case to gain 100% confidence • Transport specification should be revised in conjunction with TS-SU to alleviate last point • No showstopper so far MARIC, 28th of April 2004, First experimental results on stability of cryodipoles with central support post blocked, by Fabien Seyvet

15. References [1] LHC-PROJECT-NOTE-340; 31 Mar 2004 , Executive summary of the workshop on LHC dipole geometry and stability and preparation for the implementation of changes. M. Bajko et al. [2] LHC-PROJECT-NOTE-XXX; Analysis of the geometry of LHC dipole cold mass, tools and support. Elena Wildner et al. [3] 18th International Conference on Magnet Technology; 2003; Magnetic alignment measurements at room and cryogenic temperature of LHC cryodipoles and associated correctors. M. Buzio et al. [4] WGA workshop, 16th march 2004, Admissible loads on support post; presentation by Vittorio Parma [5] Draft Test Report; 27.04.2004; Standard non destructive mechanical axial compression and shear testing of two damaged LHC Dipole GFRE support feet; M. Struik. [6] AT-MAS Technical Note 2000-XX, April 2004, Transversal inertial loads on lHC main bending dipole. M. La China et al. [7] LHC-PROJECT-NOTE 339; LHC Dipole Geometry Stability, 23-04-2004; Dominique M. et al. MARIC, 28th of April 2004, First experimental results on stability of cryodipoles with central support post blocked, by Fabien Seyvet

16. Acknowledgements • ST-SU: Dominique Missiaen, Monique Dupont, Pierre-Marie Fougeray and team • AT-MAS: Elena Wildner; Jerome Beauquis; Davide Tommasini; Jose Lopes; Logistics team • AT-MTM: Stephane San Filippo; Juan Garcia; Marco Buzio; Luca Bottura; Vinod Chohan; Mirco Coccoli; operators team • AB-ABP: Bernard Jeanneret • ST-IC: Bertrand Nicquevert; transport team • AT-CRI: Vittorio Parma; Michel Souchet; Charles Flament; • ICS: Logistics team MARIC, 28th of April 2004, First experimental results on stability of cryodipoles with central support post blocked, by Fabien Seyvet