Nuclear level density and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>γ</mml:mi></mml:math>-ray strength function of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Ni</mml:mi><mml:mprescripts/><mml:none/><mml:mn>63</mml:mn></mml:mmultiscripts></mml:math>
V. W. Ingeberg, Peter G. Jones, L. Msebi, S. Siem, M. Wiedeking, A. A. Avaa, M. V. Chisapi, E. A. Lawrie, K. L. Malatji, L. Makhathini, S. P. Noncolela, O. Shirinda
Abstract
The nuclear level density (NLD) and $\ensuremath{\gamma}$-ray strength function ($\ensuremath{\gamma}\mathrm{SF}$) of $^{63}\mathrm{Ni}$ have been investigated using the Oslo method. The extracted NLD is compared with previous measurements using particle evaporation and those found from neutron resonance spacing. The $\ensuremath{\gamma}\mathrm{SF}$ was found to feature a strong low-energy enhancement that could be explained as $M1$ strength based on large-scale shell model calculations. Comparison of $\ensuremath{\gamma}\mathrm{SFs}$ measured with the Oslo method for various $\mathrm{Ni}$ isotopes reveals systematic changes to the strength below $5\phantom{\rule{0.222222em}{0ex}}\mathrm{MeV}$ with increasing mass.