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Study of Nuclear Level Density and γ-Strength Function in 90Zr, 196Pt, and 197Pt

Byun, Youngshin

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2013, Doctor of Philosophy (PhD), Ohio University, Physics and Astronomy (Arts and Sciences).
Nuclear level density and γ-strength functions have been investigated with two independent experimental methods; one is the evaporation method for 90Zr by the (d,n) reaction on 89Y and the other one is the Oslo method for 196Pt and 197Pt by the (p,pγ) and (d,pγ) reactions on 196Pt, respectively. The experimental cross sections of 89Y(d,n) were compared with EMPIRE calculations. Comparison indicates that the energy dependence of the neutron evaporation cross sections is consistent with the one from theoretical calculation but the magnitude of our experimental data points is lower than calculations by a factor of 2. In the measured cross section, broad peaks are also observed at the outgoing neutron energies of 8.5-10 MeV and 10-11.5 MeV for the bombarding deuteron energies of 6 and 7.5 MeV, respectively. These peaks might be produced due to strongly populated states 0+, 4-, and 5- of 90Zr via direct reactions. The experimental level density of 90Zr is compared with the Fermi-gas and the constant temperature models. We also found the step structure located at Ex = 4 MeV, resulting from the breaking of Cooper pairs. The measured strength function of 197Pt was compared to the experimental data of 198Au taken from Ref. [1]. The extracted parameters of the pygmy resonance for 197Pt show good agreement with the ones for 198Au, implying that both nuclei have the similar nuclear structure. However, several pronounced lines due to contamination by the aluminum exposed to a proton beam in the 196Pt(p,pγ) reaction are found in the coincidence matrix of 196Pt. The new coincidence matrix, which is free of those Al peaks, was obtained by putting a gate on the 2+ to 0+ γ-transition populating the ground state of 196Pt. As a result, consistent results were obtained between 197Pt and 196Pt data. Comparing to theoretical models, we can conclude that the Lorentzian with the energy dependent damping width with the varying temperature and the generalized Lorentzian model with the constant temperature reproduce the measured γ-strength functions for 197Pt and 196Pt well.
Steven Grimes, PhD (Advisor)
Alexander Voinov, PhD (Advisor)
Douglas Green, PhD (Committee Member)
Carl Brune, PhD (Committee Member)
Daniel Phillips, PhD (Committee Member)
148 p.

Recommended Citations

Citations

  • Byun, Y. (2013). Study of Nuclear Level Density and γ-Strength Function in 90Zr, 196Pt, and 197Pt [Doctoral dissertation, Ohio University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1384464244

    APA Style (7th edition)

  • Byun, Youngshin. Study of Nuclear Level Density and γ-Strength Function in 90Zr, 196Pt, and 197Pt. 2013. Ohio University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1384464244.

    MLA Style (8th edition)

  • Byun, Youngshin. "Study of Nuclear Level Density and γ-Strength Function in 90Zr, 196Pt, and 197Pt." Doctoral dissertation, Ohio University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1384464244

    Chicago Manual of Style (17th edition)