Figure 1

Normalized level densities of ${}^{119}\mathrm{Sn}$ (upper panel) and ${}^{118}\mathrm{Sn}$ (lower panel) as a function of excitation energy. Our experimental data are marked with filled squares. The dashed lines are the BSFG predictions that are used for interpolation, scaled to coincide with $\rho (S_n)$ (open squares), which are calculated from neutron resonance data. The solid lines represent the discrete level densities obtained from counting the known levels. The arrows indicate the regions used to normalize the absolute values and the slope. The energy bins are 360 and 240 keV/ch for ${}^{118,119}\mathrm{Sn}$, respectively.Reuse & Permissions

Figure 2

Comparison of the BSFG model (dashed line) and the CT model (solid line) as interpolation means for the level density of ${}^{118}\mathrm{Sn}$. The arrows indicate the region of normalization. The parameters in the CT model ($T=0.86$ MeV and $E_0=-1.7$ MeV) have been found from a least ${\chi }^2$ fit to the data points in this region and from matching $\rho (S_n)$, and the parametrization is not intended to be appropriate elsewhere.Reuse & Permissions

Figure 3

(Upper panel) Experimental pseudo entropies $S_l$ of ${}^{119}\mathrm{Sn}$ (filled squares) and ${}^{118}\mathrm{Sn}$ (open squares) as a function of excitation energy. (Lower panel) The respective experimental entropy difference, $\Delta S={S_l}^{119}-{S_l}^{118}$, as a function of excitation energy. An average value of $\overline{\Delta S}(E)=1.7\pm 0.2\hspace{0.5em}{k}_B$ is obtained from a ${\chi }^2$ fit (dashed line) to the experimental data above $~$3 MeV.Reuse & Permissions

Figure 4

The Nilsson level scheme, showing single-particle energies as functions of quadrupole deformation ${\epsilon }_2$, for ${}^{118}\mathrm{Sn}$, which has ${\epsilon }_2=0.111$. The Nilsson parameters are set to $\kappa =0.070$ and $\mu =0.48$. The Fermi levels are illustrated as curled lines (${\lambda }_{\pi }$ for protons and ${\lambda }_{\nu }$ for neutrons).Reuse & Permissions

Figure 5

Level densities of ${}^{119}\mathrm{Sn}$ (upper panel) and ${}^{118}\mathrm{Sn}$ (lower panel) as a function of excitation energy. The solid lines are the theoretical predictions of the combinatorial BCS model. The squares are our experimental data.Reuse & Permissions

Figure 6

The average number of broken quasiparticle pairs $\langle N_{\mathit{qp}}\rangle$ (solid line) as a function of excitation enegy for ${}^{119}\mathrm{Sn}$ (upper panel) and ${}^{118}\mathrm{Sn}$ (lower panel), according to the combinatorial BCS model. Also shown is how this quantity breaks down into neutron pairs (dashed line) and proton pairs (dashed-dotted line).Reuse & Permissions

Figure 7

The impact of collective effects on the level density of ${}^{119}\mathrm{Sn}$ according to the combinatorial BCS model. The upper panel shows experimental level density (data points) compared with model calculations with collective effects (solid line) and without collective effects (dashed line). The lower panel shows the corresponding enhancement factor of the collective effects, $F_{\mathrm{coll}}$ (linear scale).Reuse & Permissions

Figure 8

The parity asymmetry function $\alpha$, according to the combinatorial BCS model, shown as a function of excitation energy for ${}^{119}\mathrm{Sn}$ (upper panel) and ${}^{118}\mathrm{Sn}$ (lower panel).Reuse & Permissions

Figure 9

Comparison of spin distributions in ${}^{118}\mathrm{Sn}$ at different excitation energies. The open squares are calculated from the combinatorial BCS model in Eq. (21), while the solid lines are the predictions of Gilbert and Cameron in Eq. (4). The spin distributions are normalized to 1.Reuse & Permissions

Figure 10

Normalized $\gamma$-ray strength functions as functions of $\gamma$-ray energy. The upper panels show ${}^{119}\mathrm{Sn}$ (left) and both present and previously published versions of ${}^{117}\mathrm{Sn}$ (right). The energy bins 120 and 240 keV/ch for ${}^{117,119}\mathrm{Sn}$, respectively. The lower panels show ${}^{118}\mathrm{Sn}$ (left) and ${}^{116}\mathrm{Sn}$ (right) with the energy bins of 360 and 120 keV/ch, respectively.Reuse & Permissions

Figure 11

The four normalized strength functions of ${}^{116-119}\mathrm{Sn}$ shown together.Reuse & Permissions

Figure 12

Comparison of theoretical predictions including pygmy fits with experimental measurements for ${}^{116-119}\mathrm{Sn}$. The total strengths (solid lines) are modeled as Gaussian pygmy additions to the GLO ($E1$ $+$ $M1$) baselines. The SLO ($E1$ $+$ $M1$) baselines are also shown, failing to reproduce the measurements for low $E_{\gamma }$. The arrows indicate the neutron separation energies $S_n$. (Upper left panel) Comparison of theoretical predictions of ${}^{119}\mathrm{Sn}$ with the Oslo measurements, ${}^{117}\mathrm{Sn}(\gamma ,n)$ from Utsunomiya et al. [29], ${}^{119}\mathrm{Sn}(\gamma ,x)$ from Fultz et al. [31], and ${}^{119}\mathrm{Sn}(\gamma ,n)$ from Varlamov et al. [30]. (Upper right panel) Comparison of theoretical predictions of ${}^{117}\mathrm{Sn}$ with the Oslo measurements, ${}^{117}\mathrm{Sn}(\gamma ,n)$ from Utsunomiya et al. [29], ${}^{117}\mathrm{Sn}(\gamma ,x)$ from Fultz et al. [31], ${}^{117}\mathrm{Sn}(\gamma ,x)$ from Varlamov et al. [32], and ${}^{117}\mathrm{Sn}(\gamma ,x)$ from Leprêtre et al. [33]. (Lower left panel) Comparison of theoretical predictions of ${}^{118}\mathrm{Sn}$ with the Oslo measurements multiplied with 1.8 (filled squares) (the measurements with the original normalization are also included as open squares), ${}^{116}\mathrm{Sn}(\gamma ,n)$ from Utsunomiya et al. [29], ${}^{118}\mathrm{Sn}(\gamma ,x)$ from Fultz et al. [31], ${}^{118}\mathrm{Sn}(\gamma ,x)$ from Varlamov et al. [32], and ${}^{118}\mathrm{Sn}(\gamma ,x)$ from Leprêtre et al. [33]. (Lower right panel) Comparison of theoretical predictions of ${}^{116}\mathrm{Sn}$ with the Oslo measurements, ${}^{116}\mathrm{Sn}(\gamma ,n)$ from Utsunomiya et al. [29], ${}^{116}\mathrm{Sn}(\gamma ,x)$ from Fultz et al. [31], ${}^{116}\mathrm{Sn}(\gamma ,x)$ from Varlamov et al. [32], and ${}^{116}\mathrm{Sn}(\gamma ,x)$ from Leprêtre et al. [33].Reuse & Permissions