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α - particle Optical Potential for astrophysical studies M. Avrigeanu and V. Avrigeanu

α - particle Optical Potential for astrophysical studies M. Avrigeanu and V. Avrigeanu "Horia Hulubei" National Institute for Physics & Nuclear Engineering, Bucharest, Romania α - OMP extended analysis: 50<A<209 , E ~ 8-50 MeV

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α - particle Optical Potential for astrophysical studies M. Avrigeanu and V. Avrigeanu

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  1. α - particle Optical Potential for astrophysical studies • M. Avrigeanu and V. Avrigeanu • "Horia Hulubei" National Institute for Physics & Nuclear Engineering, Bucharest, Romania • α- OMP extended analysis: 50<A<209, E~8-50 MeV • Analysis of α elastic scattering angular distributions @ energies >BC • Analysis of (α,γ), (α,n), and (α,p) reaction data @ energies <BC 28th Int. Workshop. on Nuclear Theory Rila Mountains 2009

  2. a-nucleus OMP: OPEN QUESTIONS • OMPs from (a,a0)@Ea>80 MeV: DO NOT DESCRIBE (a,a0) @Ea<40 MeV • [Nolte+, Phys. Rev. C 36, 1312 (1987)] • OMPs from (x,a) @Ea<40 MeV:DO NOT DESCRIBE (α,α0) reactions • - astrophysical interest • - applied interest: He damage effects • [Avrigeanu+, Phys.Rev. C 49, 2136(1994)] • [Avrigeanu+, Nucl.Phys. A764,246(2006)] ! ? Marilena Avrigeanu 28th Int. Workshop. on Nuclear Theory Rila Mountains 2009 2

  3. a-nucleus OMP: OPEN QUESTIONS • OMPs from (a,a0)@Ea>80 MeV: DO NOT DESCRIBE (a,a0) @Ea<40 MeV • [Nolte+, Phys. Rev. C 36, 1312 (1987)] • OMPs from (x,a) @Ea<40 MeV:DO NOT DESCRIBE (α,α0) reactions • - astrophysical interest • - applied interest: He damage effects • [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 • [Avrigeanu+, Nucl.Phys. A723,104(2003)] • [Avrigeanu+, Phys.Rev C 73,038801(2006)] Marilena Avrigeanu 28th Int. Workshop. on Nuclear Theory Rila Mountains 2009 3

  4. Nuclear Model Calculations • OPTICAL MODEL: prime tool for all cross section calculations • Phenomenological OMP - still extensively used - while itsuncertaintiescritically depend on: - particular alpha-nucleus system -incident energy -precision of analyzed data • Microscopic OPs:reduced uncertainties (e.g., OM ambiguities) • Pure elastic scattering OP analysis SCAT2 [O. Bersillon] - phenomenological OP + semi-microscopic (DF) OP (local version) • Coupled Reaction Channel (CRC) FRESCO-2003 [I.J. Thompson] - elastic transfer among weakly bound systems • Composite system equilibration - Geometry Dependent Hybrid (GDH) preequilibrium-emission model • - Hauser-Feshbach (HF)statistical model • STAPRE-H95 [V. Avrigeanu, M. Avrigeanu] (updated) 28th Int. Workshop. on Nuclear Theory Rila Mountains 2009

  5. Microscopic Real Optical Potential [ M.A. et al. : Nucl. Phys. A 723 (2003)104 ] Marilena Avrigeanu 28th Int. Workshop. on Nuclear Theory Rila Mountains 2009 5

  6. α-particle elastic-scattering analysis to 50<A<124 @ E<50 MeV At. Data Nucl. Data Tables 95 (2009) 501 50<A<124 28th Int. Workshop. on Nuclear Theory Rila Mountains 2009

  7. DF-real & phenomenological imaginary potential for A~60 @ E<50 MeV UDF WV,WD 28th Int. Workshop. on Nuclear Theory Rila Mountains 2009 7

  8. Phenomenological optical potential for E<30 MeV 28th Int. Workshop. on Nuclear Theory Rila Mountains 2009

  9. Real Potential Volume Integral Marilena Avrigeanu 28th Int. Workshop. on Nuclear Theory Rila Mountains 2009 RIPL-3, IAEA-Vienna, 10-14 December 2007 9

  10. Local OMP parameter sets Marilena Avrigeanu 28th Int. Workshop. on Nuclear Theory Rila Mountains 2009 RIPL-3, IAEA-Vienna, 10-14 December 2007 10

  11. Local OMP parameter sets Marilena Avrigeanu 28th Int. Workshop. on Nuclear Theory Rila Mountains 2009 11

  12. ROP: (I) Settling OM-parametrization: α-particle elastic scattering @ E<20 MeV 28th Int. Workshop. on Nuclear Theory Rila Mountains 2009

  13. α-particle elastic scattering & induced reactions @ E<50 MeV ROP: A<124 E2=0.9 BC OMPs from (α,α0) @ Eα>BC (elastic scattering) DO NOT DESCRIBE (α,x) reactions@ Eα<BC E2=0.9 BC E2=0.9 BC E2=0.9 BC 28th Int. Workshop. on Nuclear Theory Rila Mountains 2009

  14. ROP: (II) Settling OM-parametrization: α-particle induced reactions at E<Bc 28th Int. Workshop. on Nuclear Theory Rila Mountains 2009

  15. ROP: (II) Settling OM-parametrization: α-particle induced reactions at E<Bc 28th Int. Workshop. on Nuclear Theory Rila Mountains 2009

  16. ROP: (II) Latest check for α-particle induced reactions at E<Bc (12 June 2009) [ ADNDT 95 (2009) 501; Phys.Rev. C 79 (2009) 027601 ] 28th Int. Workshop. on Nuclear Theory Rila Mountains 2009

  17. α-particle elastic-scattering analysis to 50<A<209 @ E<50 MeV At. Data Nucl. Data Tables 95 (2009) 501 50<A<124 Extension up to A=209 28th Int. Workshop. on Nuclear Theory Rila Mountains 2009

  18. DF-real & phenomenological imaginary potential for A ≥ 132 @ E<30 MeV UDF WD & WV 28th Int. Workshop. on Nuclear Theory Rila Mountains 2009

  19. Local OMP parameter sets: A>124 28th Int. Workshop. on Nuclear Theory Rila Mountains 2009

  20. Phenomenological optical potential for A ≥ 132 @ E<30 MeV 28th Int. Workshop. on Nuclear Theory Rila Mountains 2009

  21. α-particle elastic scattering & induced reactions @ E<50 MeV ROP: EXTENDED VR=41.75 + 0.7*Z/A1/3 + 321/ E1/2 aR=0.631 + 0016*Z/A1/3 – 0.001*Z/A1/3 E2 E2< E<26.5 aR=0.631 + 0016*Z/A1/3 – 0.001*Z/A1/3 E E>26.5 aR=0.684 - 0016*Z/A1/3 + (0.00026*Z/A1/3 – 0.0026)E E2=0.9 BC 28th Int. Workshop. on Nuclear Theory Rila Mountains 2009

  22. ROP - Extended ROP 28th Int. Workshop. on Nuclear Theory Rila Mountains 2009

  23. α-particle elastic scattering & induced reactions @ E<50 MeV ROP: EXTENDED VR=41.75 + 0.7*Z/A1/3 + 321/ E1/2 aR=0.631 + 0016*Z/A1/3 – 0.001*Z/A1/3 E2 E2< E<26.5 aR=0.631 + 0016*Z/A1/3 – 0.001*Z/A1/3 E E>26.5 aR=0.684 - 0016*Z/A1/3 + (0.00026*Z/A1/3 – 0.0026)E WD=1.5+0.5 E2=0.9 BC 28th Int. Workshop. on Nuclear Theory Rila Mountains 2009

  24. EXTENDED ROP: (II) Settling OM-parametrization: σ(α,X) at E<Bc 28th Int. Workshop. on Nuclear Theory Rila Mountains 2009

  25. EXTENDED ROP: (II) Settling OM-parametrization: σ(α,X) at E<Bc 28th Int. Workshop. on Nuclear Theory Rila Mountains 2009

  26. Conclusions • Extension ofa-nucleusOMP analysisbelow BC • (α,α) data basis(α,x) data basis • A=50-209, E~8-50 MeV • - comparison with BARC (2006) • Description ofα elasticscatteringa. d.@ energies >BC • Description of (α,x)reaction cross sections @ energies ~ 8 MeV • α-nucleus OMP in theincident channel @ energies< BC • - constant aR (Ecm/BC ~0.9)← (α,α) analysis • - increasing WD from 0-4 MeVto WD(Ecm/BC ~0.9)←(α,α) analysis Thank you ! 28th Int. Workshop. on Nuclear Theory Rila Mountains 2009

  27. 28th Int. Workshop. on Nuclear Theory Rila Mountains 2009

  28. 28th Int. Workshop. on Nuclear Theory Rila Mountains 2009

  29. Sensitivity to other model parameters: gamma parameterization 28th Int. Workshop. on Nuclear Theory Rila Mountains 2009

  30. 28th Int. Workshop. on Nuclear Theory Rila Mountains 2009

  31. Thank you ! 28th Int. Workshop. on Nuclear Theory Rila Mountains 2009

  32. 28th Int. Workshop. on Nuclear Theory Rila Mountains 2009

  33. OMPs describinga-emission: not suitable for a induced reactions ? ! Marilena Avrigeanu 28th Int. Workshop. on Nuclear Theory Rila Mountains 2009 RIPL-3, IAEA-Vienna, 10-14 December 2007 33

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