1. CENTRO ATOMICO BARILOCHE - ARGENTINA

2. MODELING AND MEASUREMENTS OF NEUTRONIC PROPERTIES OF NEW CRYOGENIC NEUTRON MODERATORS CENTRO ATOMICO BARILOCHE - ARGENTINA J.R. Granada, F. Cantargi, S. Petriw, J. Dawidowski Centro Atómico Bariloche Comisión Nacional de Energía Atómica & CONICET ARGENTINA

3. CENTRO ATOMICO BARILOCHE - ARGENTINA NyR - SOME RESEARCH ACTIVITIES Total Cross Section Measurement and Calculation (subthermal to epithermal range) [+T] Neutron Diffraction [+T] Deep Inelastic Neutron Scattering [+T] Non Destructive Hydrogen Content Determination Scattering Kernels for Hydrogeneous Materials

4. CENTRO ATOMICO BARILOCHE - ARGENTINA Scattering Kernels for Hydrogeneous Materials Previous Related Experience: THE SYNTHETIC SCATTERING FUNCTION [J.R. Granada, Phys.Rev. B 31, 4167 (1985)]

5. ANGULAR DISTRIBUTIONS Experiment performed at the Orphee reactor (λ=0.7045 Ả) TOTAL CROSS SECTIONS Light water and plexiglass at room temperature

6. DIFFUSION PARAMETERS Pulse decay time for a traditional “Hokkaido configuration” DIFFUSION PARAMETERS Decay constant of heavy water at room temperature J.Nucl.Mat. 139, 158 (1986)

7. Multiple scattering corrections to the observed spectra (MARI experiment) Phys.Rev. B 58, 706 (1998)

8. CENTRO ATOMICO BARILOCHE - ARGENTINA

9. SYNTHETIC SCATTERING KERNELS Phys.Rev. B 31, 4167 (1985) CENTRO ATOMICO BARILOCHE - ARGENTINA

11. Cross sections calculated through ‘synthetic model’ compared with exp. data at different temperatures Cryogenic Moderators

12. CENTRO ATOMICO BARILOCHE - ARGENTINA Development of New Cold Neutron Moderators (Main objective of the ACoM collaboration) SCATTERING KERNELS FOR ADVANCED MODERATOR MATERIALS

13. CENTRO ATOMICO BARILOCHE - ARGENTINA NJOY Calculations Synthetic Frequency Spectrum Combination of experimental and synthetic contributions  Continuous part associated to traslational and rotational motions of the molecular system  Vibrational modes (discretes)

14. NJOY (library ENDF)  scattering mass Scattering proc SFS Gaussian approx. 100 phonons S(Q  ) [SFS] LEAPR S(Q  ) [SFS]  (E) kernels [SFS] integrals library ACE [SFS] THERMRACER

15. Solid Methane: applications of the SFS concept

16. Solid Methane: using SFS Neutron spectra at different temps calculated with MCNP using SFS´based libraries. Neutron spectra at different temps calculated with MCNP using SFS´based libraries.

17. Light Water Ice Cross Sections obtained from SFS

18. Clathrate Neutron X-sections and spectra calculated with the use of a Synth. Frequency Spectrum

19. Clathrate Clathrate, Methane and Ice at 20K

20. Cross sections calculated through ‘synthetic model’ compared with exp. data at different temperatures Cryogenic Moderators

21. Neutron spectra from moderator substances at different temperatures (calculated) Cryogenic Moderators

22. Calculated spectra of typical cryogenic moderators for the “Hokkaido Configuration”

23. CENTRO ATOMICO BARILOCHE - ARGENTINA SCATTERING KERNELS FOR ADVANCED MODERATOR MATERIALS Latest Development of New Cold Neutron Moderators

24. CENTRO ATOMICO BARILOCHE - ARGENTINA Neutron Scattering Kernel for Solid Methane in phase II Rolando Granada Centro Atomico Bariloche ARGENTINA

25. CENTRO ATOMICO BARILOCHE - ARGENTINA

26. The scattering law of a molecular system R lν (t) denotes the position of the atom v within the molecule l, can be written as the sum of inter (l  l´)- and intra (l  l´)- molecular contributions (also referred to as the outer and inner terms, respectively). The intermediate scattering function is

27. CENTRO ATOMICO BARILOCHE - ARGENTINA Carbon selfHydrogen self Interference caused by Proton spin correlations g Г = 1 for disordered molecules = 3 for ordered molecules

28. CENTRO ATOMICO BARILOCHE - ARGENTINA Calculated components of σ T (E) for CH 4 II at 4K CH 4 II

29. CENTRO ATOMICO BARILOCHE - ARGENTINA Comparison of calculated σ T (E) with experimental data of Grieger et al. J.Chem.Phys.109,3161 (1998) CH 4 II

30. CENTRO ATOMICO BARILOCHE - ARGENTINA Temperature dependence of σ T at low energies caused by spin correlations Open circles: this work Closed circl.: Grieger exper. Lines: Ozaki calculations CH 4 II

31. CENTRO ATOMICO BARILOCHE - ARGENTINA

32. Neutron Cross Section Libraries for Aromatic Systems of interest as Cold Neutron Moderators F. Cantargi, J.R. Granada, L.A. Rodríguez Palomino, S. Petriw, M.M. Sbaffoni Centro Atomico Bariloche ARGENTINA

33. CENTRO ATOMICO BARILOCHE - ARGENTINA Good moderator for a cold neutron source  good resistance to radiation (S.Kulikov, E. Shabalin, V. Melikhov, E. Kulagin, Proceedings of the ICANS-XVI Meeting, Neuss, Germany, 2003)  high protonic density  low-energy excitations (I. Natkaniec, Proceedings of the ACoM6 Meeting, ESS-FZ Julich, 2002)  easy handling MESITYLENE

34. CENTRO ATOMICO BARILOCHE - ARGENTINA Low energy part of our adopted SFS

35. CENTRO ATOMICO BARILOCHE - ARGENTINA (Phase III) Experiments using the Bariloche LINAC

36. CENTRO ATOMICO BARILOCHE - ARGENTINA Experiments using the Bariloche LINAC

37. CENTRO ATOMICO BARILOCHE - ARGENTINA Calculated Spectra for the Methyl derivatives of Benzene

38. CENTRO ATOMICO BARILOCHE - ARGENTINA Comparison of Mesitylene and Mixture with standard moderators

39. CENTRO ATOMICO BARILOCHE - ARGENTINA Thank you!

40. CENTRO ATOMICO BARILOCHE - ARGENTINA

41. 25 MeV e-LINAC

43. 73 cm total height; 50 cm diameter; 38 cm moderator height. Stainless steel. Zircaloy-4 windows Cryogenic Moderators

44. Cryo-Moderator contained in succession of zircalloy-4 containers Cryogenic Moderators

45. CENTRO ATOMICO BARILOCHE - ARGENTINA