Nuclear level density and $\gamma$-ray strength function of ${}^{43}$Sc

The nuclear level density and the $\gamma$-ray strength function have been determined for ${}^{43}\mathrm{Sc}$ in the energy range up to 2 MeV below the neutron separation energy using the Oslo method with the $46\mathrm{Ti}$$(p,\alpha )$${}^{43}\mathrm{Sc}$ reaction. A comparison to ${}^{45}\mathrm{Sc}$ shows that the level density of ${}^{43}\mathrm{Sc}$ is smaller by an approximately constant factor of two. This behavior is well reproduced in a microscopic, combinatorial model calculation. The $\gamma$-ray strength function increases at low $\gamma$-ray energies, a feature which has been observed in several nuclei but which still awaits theoretical explanation.

Figure 1

Alpha spectra from the $46\mathrm{Ti}$($p,\alpha$)${}^{43}\mathrm{Sc}$ reaction: Oslo data from one particle telescope (black solid line), data from Abou-Zeid et al. scaled by a factor of 10 (blue dashed line, from Ref. [8]), and the Abou-Zeid data folded with a Gaussian of 700 keV FWHM and scaled by a factor of 40 (red line).

Figure 2

Experimental level density for ${}^{43}\mathrm{Sc}$. The experimental curve (blue steps) is normalized to discrete levels (green steps, fit in green region) and to proton resonance spacings (cyan diamond) extrapolated using a BSFG model (red line, fit in the red region).

Figure 3

Level-density comparison. The experimental level density for ${}^{43}\mathrm{Sc}$ (blue steps) is compared to the experimental level density of ${}^{45}\mathrm{Sc}$ (red steps) [2] and to combinatorial model calculations for these two nuclei (blue and red lines for ${}^{43}\mathrm{Sc}$ and ${}^{45}\mathrm{Sc}$, respectively), see text. In addition, BSFG calculations are included for ${}^{43}\mathrm{Sc}$ and ${}^{45}\mathrm{Sc}$ (blue and red dashed lines, respectively).

Figure 4

$\gamma$-ray strength function for ${}^{43}\mathrm{Sc}$. The experimental curve (blue steps) is shown together with the $\gamma$-ray strength function for ${}^{45}\mathrm{Sc}$ (red steps). The normalization data point from ${}^{46}$Sc is also shown (cyan diamond).