Negative-parity high-spin states and a possible magnetic rotation band in ${}_{59}{}^{135}\mathrm{Pr}_{76}$

Excited states in ${}^{135}\mathrm{Pr}$ have been investigated using the reaction ${}^{123}\mathrm{Sb}({}^{16}\mathrm{O},4n){}^{135}\mathrm{Pr}$ at an incident beam energy of 82 MeV. The partial level scheme has been established for negative-parity states with addition of new $\gamma$-ray transitions. The directional correlation and polarization measurements have been performed to assign spin parity for most of the reported $\gamma$-ray transitions. At high spin, a negative-parity dipole band $\left(\mathrm{\Delta }I=1\right)$ has been reported along with the observation of new crossover $E2$ transitions. Tilted Axis Cranking (TAC) calculations have been performed by considering a three-quasiparticle (3qp) configuration $\pi {\left(h_{11/2}\right)}^1\otimes \nu {\left(h_{11/2}\right)}^{-2}$ and a five-quasiparticle (5qp) configuration $\pi {\left(h_{11/2}\right)}^1{\left(g_{7/2}\right)}^2\otimes \nu {\left(h_{11/2}\right)}^{-2}$ for the lower and upper parts of the band, respectively. The observed results are compared with the results of the theoretical (TAC) calculations.

Figure 1

The partial level scheme of ${}^{135}\mathrm{Pr}$ deduced from the present work. New transitions are marked with an asterisk $(*)$.

Figure 2

(a),(c) Sum of gated $\gamma \text{−}\gamma$ coincidence spectra. (b),(d) Sum of double-gated spectrum with 844 keV and 373, 660, 854, and 1000 keV (see text for explanation).

Figure 3

(a),(c) Sum of gated $\gamma \text{−}\gamma$ coincidence spectra. (b),(d) Sum of double-gated spectrum with 424 keV and 373, 660, 854, and 1000 keV. (Transitions belonging to band 3 are marked in italics in all the spectra). The contaminant transitions are marked with an asterisk (*).

Figure 4

Coincidence spectra showing the crossover transitions in band 3 (marked with a “+” sign).

Figure 5

(a) Comparison of the $I\left(\hslash \right)$ vs $\hslash \omega$ behavior with TAC calculations. (b) Experimental and calculated $B\left(M1\right)/B\left(E2\right)$ ratios as functions of $I\left(\hslash \right)$ for band 3.

Figure 6

$I\left(\hslash \right)$ vs $\hslash \omega$ behavior of dipole bands in ${}^{135}\mathrm{Pr}$ and ${}^{137}\mathrm{Pr}$.

Figure 7

Variation of observed $B\left(M1\right)/B\left(E2\right)$ ratios as functions of $I\left(\hslash \right)$ for dipole bands in ${}^{135}\mathrm{Pr}$ and ${}^{137}\mathrm{Pr}$.

Figure 8

Experimental energy vs spin $I\left(\hslash \right)$ for dipole bands in ${}^{135}\mathrm{Pr}$ and ${}^{137}\mathrm{Pr}$. The fitted lines are guides for seeing the band crossings.