Characterization of superdeformed bands in ${}^{62}\mathrm{Zn}$

Combined data from four fusion-evaporation reaction experiments were utilized to investigate deformed and superdeformed structures in ${}_{30}^{62}{\mathrm{Zn}}_{32}$. Combination of the Gammasphere $\gamma$-ray spectrometer and ancillary particle detection systems allowed for the connection of rotational bands to well-known, low-lying excited states in ${}^{62}\mathrm{Zn}$, as well as spectroscopy of discrete high-spin states reaching excitation energies of $E_x=42.5$ MeV. Four well- or superdeformed bands in ${}^{62}\mathrm{Zn}$ are characterized and described by means of cranked Nilsson-Strutinsky calculations.

Figure 1

Partial decay scheme of ${}^{62}\mathrm{Zn}$. Energy values are given as kilo-electron volts, and the widths of the arrows correspond to the relative intensities of the $\gamma$ rays.

Figure 2

(a) $\gamma$-ray spectrum in coincidence with any combination of two of the 1993-, 2214-, 2439-, 2690-, 2939-, and 3234-keV transitions of SD1 taken from $\mathtt{data\; set\; 1}$. (b) $\gamma$-ray spectrum generated from $\mathtt{data\; set\; 2}$ by coincidence requirements on the 2214-, 2439-, 2690-, 2939-, 3234-, and 3579-keV transitions in SD1. $\gamma$-ray labels are kilo-electron volts, the binning is 4 keV per channel, and an asterisk or italic labeling indicates lines from the lower part of the ${}^{62}\mathrm{Zn}$ decay scheme in Fig. 1.

Figure 3

A sample of $\gamma$-ray spectra taken from $\mathtt{data\; set\; 1}$. (a) Spectrum in coincidence with any combination of the 2309-, 2565-, and 2816-keV and the 1842-, 2058-, 2309-, 2565-, 2816-, and 3051-keV transitions of SD2. (b) Spectrum in coincidence with any combination of the 2180-, 2485-, 2832-, and 3299-keV and the 1860-, 1962-, 2180-, 2485-, 2832-, and 3299-keV transitions of WD1. (c) Spectrum in coincidence with the 5388-keV decay-out transition and any of the 2375-, 2616-, 2849-, and 3118-keV transitions of SD3. See text and caption to Fig. 2 for more details.

Figure 4

Schematic illustration of configurations considered for interpretation of the observed SD bands in ${}^{62}\mathrm{Zn}$. Filled circles indicate particles and open circles indicate holes relative to the spherical $Z=N=28$ gap. The $2p_{3/2}$ and $1f_{5/2}$ subshells are coupled to indicate that they mix strongly and are therefore treated as one entity in the configuration assignment. The $I_{\max }$ value given below each configuration is the maximum spin value that can be formed for the pure configuration according to the Pauli principle.

Figure 5

Comparison between experimentally observed structures and cranked Nilsson-Strutinsky predictions for rotational bands in ${}^{62}\mathrm{Zn}$, with the absolute energy scale fixed according to Ref. [32]. Top panels illustrate experimental energies relative to the rotating liquid drop (rld) energy, where the bands are labeled according to Fig. 1. Middle panels show the selected calculated bands. Bottom panels plot the energy difference between the predictions and the observations. Signature $\alpha =0$ is represented by filled symbols; $\alpha =1$, by open symbols. Solid (dashed) lines represent positive (negative) parity.

Figure 6

$J^{(2)}$ moments of inertia vs. rotational frequency for both observed and calculated rotational bands in ${}^{62}\mathrm{Zn}$.