1. FLUKA Meeting Milan Jul 2010 francesco.broggi@mi.infn.it Work in the frame of the LHC Phase II Upgrade Previous work was dedicated to the study of the energy deposition in the low-  inner triplet and its best layout (A.Ferrari, F.Cerutti, A. Mereghetti, C.Hoa, E. Wildner …..) Phase I : L= 2-3 x10 34 cm -2 s -1 (NbTi) Phase II : L=10 35 cm -2 s -1 (Nb 3 Sn) SIT Project Superconductor Irradiation Test

2. Outline Why Irradiation tests ? Beam needs Beam availability Geometry/energy deposition activation and cooling (no soldering) Soldering (negative) effect Next: Thermal analysis DPA analysis

3. The magnetic elements close to the LHC IP will undergo to a heavy radiation load ( At phase II it will be 10 times the the nominal one, being the Luminosity 10 times higher) Ways of reducing the radiation load are the optimization of the optics, larger aperture magnets (100-200 mm with Nb 3 Sn technology), liners, protections, ….

4. It is necessary to do irradiation tests on Nb 3 Sn cable samples, in order to predict the behaviour/degradation “spot” and old data about the radiation damage un Nb 3 Sn ~1 MeV E dNdE (part.coll. -1 cm -2 ) The neutron energy fully covers a wide interval, down to thermal energies Spectra in Q2a 100 … 200 MeV From F.Cerutti, A Mereghetti neutrons damage conductor photons damage insulators protons have lower effects ?

5. From L. Bottura slides at EuCARD workshop on insulator irradiation, CERN, December 2, 2009

8. Beam Sources (with cryogenic irradiation facility) NEUTRONS: Reactors (Atominstitut in Wien, TRIGA) Secondary Neutrons from p on Be (at the cyclotron of the Kurchatov Institute) PROTONS : Cyclotron at Kurchatov Insitute

9. p beam p on Be Ep = 30 MeV Spot size = 2 cm FWHM Be target (Cylinder) r = 5 cm, h = 2 cm 10 runs with 10 6 particles each Neutron/prError % Forward1.344E-022.692E-01 Side3.107E-035.656E-01 Back1.016E-023.114E-01

10. p on Be Values already multiplied for the energy, to have directly the number of neutrons/proton “Double differential” spectrum integrated spectrum (over angles)

11. With 20  a p current a total flux of 1.6x10 12 n/s will be avalilable (fw) from such a target Reactor fluxes ~ 10 13 - 10 14 n/cm 2 s p on Be Atominstitut reactor will provide n beam

12. The Sample Holder Ti5 Nb 3 Sn cable SimpleGeo Plot

13. Ep = 30 MeV ; Spot size = 2 cm FWHM Cooling LHe, LN 2, H 2 O (closer beam origin in case of LN 2 and H 2 O) Cut-offs = 100 keV for hadrons, and 10 keV for electrons, positrons and photons Ti5 Sample HolderNb 3 Sn CableCoolant LHe 1.16 x 10 -2  0.01%2.65 x 10 -3  0.03%1.56 x 10 -2  0.008% LN 2 1.18 x 10 -2  0.01%2.64 x 10 -3  0.02%1.54 x 10 -2  0.007% H2OH2O 9.40 x 10 -3  0.01%2.35 x 10 -3  0.02%1.82 x 10 -2  0.003% Energy deposition (GeVpr -1 ) 10 runs with 10 7 particles each Energy Deposition

14. H2OH2O LN 2 LHe bin dimensions = 1 x 1 x 1 mm 3 Energy Deposition Maps The energy/power deposed in the sample holder is about 230 J/s (40% of the primary beam). The beam spot is larger than the sample holder

15. Energy Deposition Maps LHe H2OH2O LN 2 bin dimensions = 0.1 x 0.5 x 0.5 mm 3 p beam cable p beam origin

16. Problem. The sample moves during the critical current measurements Solution (under discussion). Mechanically fix the Nb 3 Sn sample with a Sn-Pb soldering Ti5 Nb 3 Sn cable

17. Solution (only proposed) : Fix the sample with a soldering Is it reliable ? Solution ? The soldering composition is 60% Sn and 40% Pb. It is, on average, similar to Cu. 30 MeV p beam target As from literature the range of 30 MeV protons in Cu is 1.44 g/cm 2 so it is 1.6 mm being 8.96 g/cm 3 the Cu density

18. Energy Deposition Maps LHe H2OH2O LN 2 bin dimensions = 0.1 x 0.5 x 0.5 mm 3 p beam cable p beam origin soldering The energy deposition occurs in the soldering and not in the cable

19. Activation and Cooling Questions: Can be “used” such an object ? Are precautions needed ? What ?

20. Residual Nuclei Ti sample holder (lower part only) Soldering t=0t=1ht=7d

21. Temperature increase (the irradiation must not melt the cable or the sample holder) Adiabatic Hypothesis Unphysical number The specific heat at 4 K is the crucial value The adiabatic hypothesis is not valid, so thermal conductivity and thermal exchange must be taken into account. Thermal model has been developed (F.Liberati), but a thermal analysis is necessary, to have most reliable evaluations.

22. What’s Next ? Find mechanical solution better than the soldering Thermal analysis (provide the adapted USRBIN output as ANSYS input) Benchmarking of the simulations with the irradiation tests DPA evaluation (FLUKA pre-release)