1. Nuclear Level Densities of Residual Nuclei from evaporation of 64 Cu Moses B. Oginni Ohio University SNP2008 July 9, 2008

2. List of Collaborators S. M. Grimes, C. R. Brune, T. N. Massey A. V. Voinov A. S. Adekola, Z. Heinen D. Carter, D. Jacobs, J. O’Donnell Andreas Heinz (Yale University)

3. Outline Introduction Experiments and facilities Results Outlook and Conclusion

4. Introduction 4 The study of NLD based on Bethe’s idea.[*] 2 assumptions: - non-interacting fermions - single particle states are equidistant in energy. * H. A. Bethe, Phys. Rev. 50, 336 (1936)

5. MODEL PARAMETERS FOR NLD 5 General pattern for level density parameter is given as: ROHRAl-Quraishi [**] ** S.I. Al-Quraishi et al, Phys. Rev. C63, 065803(2001). a = 0.071*A + V V = 1.64 A ≤ 38 V = 3.74 38 < A ≤ 69 V = 6.78 69 < A ≤ 94 V = 8.65 94 < A < 170 a = 0.108*A + 2.4 A ≥ 170 [*] * G. Rohr, Z Phys. A – Atoms and Nuclei 318, 299 – 308 (1984). α = 0.1062, β = 0.00051 α = 0.1068, γ = 0.0389

6. Experiments 6 6 Li + 58 Fe 7 Li + 57 Fe 64 Cu p + 63 Ni n + 63 Cu α + 60 Co 6 Li + 55 Mn 61 Ni p + 60 Co n + 60 Ni α + 57 Fe

7. Edwards Accelerator Facility 7

8. beam Target Si 2m flight path Scheme of experimental set-up for charge- particle spectra measurements Edward’s Accelerator Lab, Ohio University N 8

9. Particle ID 9 TOF and E information were used to separate the charged particles. PSD and E information were used to separate the neutrons and the photons.

10. Calibrations 10 Charged Particle Energ y Calibration -elastic scattering of Li6 on Gold -elastic scattering of Li7 on Gold -elastic scattering of d on Gold -alpha source of 3 known peaks Neutron Efficiency Calibration -Using the result of Al27(d,n) reaction from Massey et al. (Nucl. Sci. and Eng.,129,175-179(1998)) as standard.

11. Angular distributions 11 Angular distribution of compound nuclear reaction is expected to be symmetric about 90 degree.

12. Proton Spectrum (I) 12

13. Proton Spectrum (II) 13

14. Alpha Spectrum (I) 14

15. Alpha Spectrum (II) 15

16. Proton Spectrum (III) 16 6 Li + 58 Fe 7 Li + 57 Fe α + 60 Co 6 Li + 55 Mnp + 60 Co

17. Deuteron Spectrum (I) 17

18. Deuteron Spectrum (II) 18

19. Break Up Study 6 Li  α + d (Q = -1.47MeV) α + n + p (Q = -3.70MeV) 5 He + p (Q = -4.59MeV) 7 Li  α + t (Q = -2.47MeV) α + d + n (Q = -8.72MeV) 5 He + d (Q = -9.61MeV) 6 He + p (Q = -9.98MeV) α + 2n + p (Q = -10.95MeV) 5 He + n + p (Q = -11.84MeV) Is the break up a 1-step process or a 2-step process ? 6 Li  6 Li*  … 7 Li  7 Li*  …

20. Energy Levels of 6 Li and 7 Li * http://www.tunl.duke.edu/ Energy levels of 6 Li Energy levels of 7 Li

21. Neutron Spectrum (I) 21

22. Neutron Spectrum (II) 22

23. Future Prospects 23 Test data with other models aside Fermi-gas Quantify the contributions of break up to our evaporation spectra. Other experiments under study are : ExperimentsZ-Zо 0 2 4

24. Conclusion 24 Rohr systematic appears to describe well protons spectra but did not do well with alpha spectra because of break-up contributions. We believe that the alpha spectra up to 8MeV cannot be used for estimating level density because of the break up contribution Our analysis shows that tentative LD parameters can be assigned as follows: 63 Ni: a = 8.21/MeV, δ = 1.51MeV 63 Cu: a = 8.21/MeV, δ = 1.51MeV 60 Co: a = 8.00/MeV, δ = 0.00MeV

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28. EXTRA SLIDES

29. Optical Parameters