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M. Avrigeanu , V. Avrigeanu , A. Obreja , and F.L. Roman

n_TOF 2007 Annual Meeting, Bari, 28-30 Nov. 2007. Contribution on neutron total and capture cross sections for Os isotopes. M. Avrigeanu , V. Avrigeanu , A. Obreja , and F.L. Roman “Horia Hulubei ” National Institute for Physics & Nuclear Engineering, Bucharest, Romania

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M. Avrigeanu , V. Avrigeanu , A. Obreja , and F.L. Roman

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  1. n_TOF 2007 Annual Meeting, Bari, 28-30 Nov. 2007 Contribution on neutron total and capture cross sections for Os isotopes • M. Avrigeanu, V. Avrigeanu, A. Obreja, and F.L. Roman • “Horia Hulubei” National Institute for Physics & Nuclear Engineering, Bucharest, Romania • http://tandem.nipne.ro/~dante/, http://fp6.cordis.lu/fp6/partners/RCN 49105 • Origin: DOM potential for Hf-Ta-W, E<100 MeV[Nucl. Phys. A765,1(2006)] • Check for Os isotopes (SPRT method): n_TOFS0 data[ND-2007 #519] • Questions on Gg0 data in RIPL-2 [ used for normalization of fE1(Eg) ] • Additional case: n_TOF capture data for186,187,188Os [PoS(NIC-IX)055] • α-nucleus OMP in the incident channel @ energies <12 MeV[EFFDOC-1022] • Analysis of (α,g), (α,n), and (α,p) reaction data [A~50, 63, 96, 112] n_TOF Collaboration Annual Meeting, Bari, 28-30 Nov. 2007

  2. 1. Results for 180,183,183,184,186W isotopes: n_TOF Collaboration Annual Meeting, Bari, 28-30 Nov. 2007

  3. [Nucl. Phys. A765, 1 (2006)] Flowchart of model calculations • EMPIRE-II v.2.19[ECIS95/SCAT2, DEGAS, MSD-TUL/MSC-H, HF] • st, sR, sCC, sabs - Tl(E) neutron deformed optical potential- p-, a- spherical optical potentials - EMPIRE-specific level density, Nmax< 40 - DEGAS [g=A/13 MeV-1, K=100 MeV3] - PCROSS • TALYS-0.64 [+ Arjan Koning] • STAPRE-H.6 (v.2006) [SCAT2, GDH, HF]- p-, a- spherical optical potentials - BSFG, E*<Bn: (a,D) D0-, Nmax-fit a(E*), E*>Bn: Junghans/Koning/Chadwick (1998) I/Ir: 0.5(g.s.)-0.75(Bn)-1(15 MeV)[Nucl. Phys. A730, 255 (2004)] - GDH + gFGM(e), AK(p,h), fK(p,h,E,F1(l,Ei) [Phys.Rev. C 58,295 (1998)] + Jp-conservation[Z.Phys. A 329,177(1988); 335,299(1990)] + medium energy l-effects[Phys. Rev. C54, 2538 (1996)] EFF/EAF Meeting, NEA, 22.5.2006

  4. Optical model potentials • Neutrons (n+182,183,184,186W, 181Ta, 178Hf):SPRT analysis(added in EMPIRE-II output) • P.G. Young+ (1990) [as RIPL-2 in EMPIRE-II] (local) • J.P. Delaroche, as in NEANDC-253”U”, OECD/NEA-DB, 1989 (local) • P.G. Young, NEANDC-222”U”, OECD/NEA-DB, 1986 (global: II-A, II-B) • P.G. Young+ (1990) - modified (local) • RIPL-2/P.G. Young+ (1986) - modified (local) • P.G. Young, OECD/NEA-DB (1986) – II-A: modified (global, E<100) • Protons (p+181Ta) • R.L. Walter and P.P. Guss, Rad. Effects 92, 1079 (1986) (global) • N. Yamamuro, NDST-1988, Mito, Japan, p.489 (global) • Walter-Guss (1986) - modified (p+181Ta) • Walter-Guss (1986) –p+180Hf • Alphas • V. Avrigeanu, P.E. Hodgson, M. Avrigeanu, Phys.Rev.C 49,2137(1994) (global) • M.Avrigeanu, W. von Oertzen, V.Avrigeanu, Nucl. Phys. A 754, 246 (2006) n_TOF Collaboration Annual Meeting, Bari, 28-30 Nov. 2007

  5. Optical model potential SPRT analysis for 183,183,184,186W isotopes n_TOF Collaboration Annual Meeting, Bari, 28-30 Nov. 2007

  6. Comparison of calculated and experimental neutron total cross sections for 178Hf, 181Ta, and 182,183,184,186W isotopes n_TOF Collaboration Annual Meeting, Bari, 28-30 Nov. 2007

  7. Optical model potential SPRT analysis for Os isotopes n_TOF Collaboration Annual Meeting, Bari, 28-30 Nov. 2007

  8. [Nucl. Phys. A765,1(2006)] 2. g-ray strength functions for A~180 • Modified energy-dependent Breit-Wigner (EDBW) model28,29: fE1(Eg) • Comparison of experimental20,30 and the calculated average radiative widths • Gg0 (meV) used for normalization of fE1(Eg) capture data description 20A.V. Ignatyuk, at http://161.5.7.5/RIPL-2/resonances/ . 28D.G. Gardner and F.S. Dietrich, Report UCRL-82998, LLNL-Livermore, 1979. 29M. Avrigeanu, V. Avrigeanu, G. Cata, and M. Ivascu, Rev. Roum. Phys. 32, 837 (1987). 30R.L. Macklin, D.M. Drake, and E.D. Arthur, Nucl. Sci. Eng. 89, 98 (1983). n_TOF Collaboration Annual Meeting, Bari, 28-30 Nov. 2007

  9. Comparison of calculated and measured neutron capture cross sections of 181Ta and 180,182-184,186W isotopes n_TOF Collaboration Annual Meeting, Bari, 28-30 Nov. 2007

  10. Comparison of calculated and measured neutron capture cross sections of 176,177,178,179,180Hf and 181Ta isotopes n_TOF Collaboration Annual Meeting, Bari, 28-30 Nov. 2007

  11. Nuclear Level Density parameters for 187,188Os × (~10) smaller uncertainty in BSFG parameters ( D-fixed ) Cumulative number of levels against excitation energy for 187,188Os and corresponding BSFG model parameters n_TOF Collaboration Annual Meeting, Bari, 28-30 Nov. 2007

  12. Nuclear Level Density parameters for 187,189Os smaller ‘scattering’ of a-values Cumulative number of levels against excitation energy for 187,189Os and corresponding BSFG model parameters n_TOF Collaboration Annual Meeting, Bari, 28-30 Nov. 2007

  13. [Nucl. Phys. A765,1(2006)] Level density parameter systematics • [ J. Nucl. Sci. Tech. Suppl. 2, 746 (2002) ] • [ Nucl. Phys. A730, 255 (2004) ] • http://tandem.nipne.ro/~vavrig/ n_TOF Collaboration Annual Meeting, Bari, 28-30 Nov. 2007

  14. Comparison of calculated and measured neutron capture cross sections of 186,187Os isotopes n_TOF Collaboration Annual Meeting, Bari, 28-30 Nov. 2007

  15. [ ND-2007 # 291 ] 3. a-nucleus OMP: OPEN QUESTIONS • phenomenological OMP - still extensively used • no global OMP parameter set for a-particles that: [RIPL, Report IAEA-TECDOC-1034, IAEA, Vienna, 1998; http://www-nds.iaea.or.at/ripl/] • describes a-particle scattering from many nuclei • over wide range of energies • with good accuracy • uncertainties of OMP parameterscritically depend on: • particular alpha-nucleus system • incident energy • precision of analyzed data • OMPs from (a,a0) @Ea>80 MeV: DO NOT DESCRIBE (a,a) @Ea<40 MeV • [Nolte+, Phys. Rev. C 36, 1312 (1987)] • OMPs from (a,a0) @Ea<40 MeV:DO NOT DESCRIBE (x,a) reactions • [Avrigeanu+, Phys.Rev. C 49, 2136(1994)] • [Avrigeanu+, Nucl.Phys. A764,246(2006)] • OMPs from (a,a0) @13<Ea<40 MeV:DO NOT DESCRIBE (a,x) reactions @Ea<12 MeV n_TOF Collaboration Annual Meeting, Bari, 28-30 Nov. 2007

  16. Improper use of OMP describinga-emission: not suitable for (a,x) @ Ea~25 MeV n_TOF Collaboration Annual Meeting, Bari, 28-30 Nov. 2007

  17. OMPs describinga-emission: not suitable for (a,a0) @ Ea~25 MeV ? ! n_TOF Collaboration Annual Meeting, Bari, 28-30 Nov. 2007

  18. Use of OMP describing(a, a) @ Ea>14 MeV : not suitable for (a,x) @ Ea<12 MeV(1/2) n_TOF Collaboration Annual Meeting, Bari, 28-30 Nov. 2007

  19. Use of OMP describing(a, a) @ Ea>14 MeV : not suitable for (a,x) @ Ea<12 MeV (2/2) n_TOF Collaboration Annual Meeting, Bari, 28-30 Nov. 2007

  20. [ ND-2007 # 291 ] Data basis of OMP analysis for A~50 - 124 @ E<50 MeV (ROP2007) Re-analysis (post-2003): n_TOF Collaboration Annual Meeting, Bari, 28-30 Nov. 2007

  21. [ ND-2007 # 291 ] Microscopic Real Optical Potential n_TOF Collaboration Annual Meeting, Bari, 28-30 Nov. 2007

  22. [ ND-2007 # 291 ] Actual extension to A~60 @ E<20 MeV: DF-real & phenomenological imaginary potential for A~60 @ E<50 MeV UDF WV,WD n_TOF Collaboration Annual Meeting, Bari, 28-30 Nov. 2007

  23. [ ND-2007 # 291 ] Phenomenological optical potential for A~60,90,120 @ E<50 MeV n_TOF Collaboration Annual Meeting, Bari, 28-30 Nov. 2007

  24. [ ND-2007 # 291 ] Model Calculations • OPTICAL MODEL: prime tool for all cross section calculations • Phenomenological OMP (global parameter sets):still extensively used • Microscopic OPs:reduced uncertainties (e.g., OM ambiguities) • Pure elastic scattering OP analysis SCAT2 [O. Bersillon] - phenomenological OP + semi-microscopic (DF) OP (local version) Phys. Rev. C62 (2000) 017001 Nucl. Phys. A693 (2001) 616 Eur. Phys. J. A12 (2001) 399 Int. J. of Mod. Phys. E, 11 (2002) 249 Nucl. Phys. A723 (2003) 104 Nucl. Phys. A 759 (2005) 327 Nucl. Phys. A 764 (2006) 246 • Coupled Reaction Channel (CRC) FRESCO-2003 [I.J. Thompson] • Composite system equilibration - Geometry Dependent Hybrid (GDH) preequilibrium-emission model • - Hauser-Feshbach(HF)statistical model • STAPRE-H95 [V. Avrigeanu, M. Avrigeanu] (updated) n_TOF Collaboration Annual Meeting, Bari, 28-30 Nov. 2007

  25. [ ND-2007 # 291 ] Accurate OMP for description of a-induced reactions:(a,n) @ Ea<12MeV, A~50 (1/3) n_TOF Collaboration Annual Meeting, Bari, 28-30 Nov. 2007

  26. [ ND-2007 # 291 ] Accurate OMP for description of a-induced reactions:(a,n) @ E<12 MeV, A~50 (2/3) n_TOF Collaboration Annual Meeting, Bari, 28-30 Nov. 2007

  27. Accurate OMP for description of a-induced reactions:(a,n) @ E<12 MeV, A~50 (3/3) n_TOF Collaboration Annual Meeting, Bari, 28-30 Nov. 2007

  28. Accurate OMP for description of a-induced reactions: (a,x) @ Ea<12MeV , A~63 (a,a) (a,g) n_TOF Collaboration Annual Meeting, Bari, 28-30 Nov. 2007

  29. [Analysis for the Pd, Sn, and Te stable isotopes of neutron total cross sections ] Koning-Delaroche(2003) OMP: +(10-15)% sT for Pd isotopes n_TOF Collaboration Annual Meeting, Bari, 28-30 Nov. 2007

  30. [Analysis for the Pd, Sn, and Te stable isotopes of (1/2) neutron capture cross sections ] n_TOF Collaboration Annual Meeting, Bari, 28-30 Nov. 2007

  31. [Analysis for the Pd, Sn, and Te stable isotopes of (2/2) neutron capture cross sections ] EDBW model normalization: n_TOF Collaboration Annual Meeting, Bari, 28-30 Nov. 2007

  32. Accurate OMP for description of a-induced reactions: (a,x) @ Ea<12MeV, A~96 n_TOF Collaboration Annual Meeting, Bari, 28-30 Nov. 2007

  33. Accurate OMP for description of a-induced reactions: (a,x) @ Ea<12MeV , A~112 n_TOF Collaboration Annual Meeting, Bari, 28-30 Nov. 2007

  34. Conclusions • Extension ofa-nucleusOMP analysisbelow BC for A>60 • (α,α) data basis (α,x) data basis • Analysis for the Pd, Sn, and Te stable isotopes of: • - neutron total cross sections • - neutron capture cross sections • Description of (α,g), (α,n), and (α,p) reaction cross section on A~50, 63, 96 and 112@ energies < 12 MeV • α-nucleus OMP in the incident channel @ energies < BC : • - constant aR(Ecm/BC ~0.9) from (α,α) analysis • - increasing WD from 0-4 MeV to WD(Ecm/BC ~0.9) from (α,α) analysis n_TOF Collaboration Annual Meeting, Bari, 28-30 Nov. 2007

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