Transition Probabilities in ${}^{134}\mathrm{Pr}$: A Test for Chirality in Nuclear Systems

Exited states in ${}^{134}\mathrm{Pr}$ were populated in the fusion-evaporation reaction ${}^{119}\mathrm{Sn}({}^{19}\mathrm{F},4n){}^{134}\mathrm{Pr}$. Recoil distance Doppler-shift and Doppler-shift attenuation measurements using the Euroball spectrometer, in conjunction with the inner Bismuth Germanate ball and the Cologne plunger, were performed at beam energies of 87 MeV and 83 MeV, respectively. Reduced transition probabilities in ${}^{134}\mathrm{Pr}$ are compared to the predictions of the two $\mathrm{\text{quasiparticle}}+\mathrm{\text{triaxial}}$ rotor and interacting boson fermion-fermion models. The experimental results do not support the presence of static chirality in ${}^{134}\mathrm{Pr}$ underlying the importance of shape fluctuations. Only within a dynamical context the presence of intrinsic chirality in ${}^{134}\mathrm{Pr}$ can be supported.

Figure 1

Partial level scheme of ${}^{134}\mathrm{Pr}$ from Ref. 16. Two nearly degenerate positive-parity bands, candidates for chiral partner bands, are indicated as Band 1 and Band 2.

Figure 2

Gated $\gamma$-ray spectra of ${}^{134}\mathrm{Pr}$ taken at four different distances. The summed spectra from all detectors positioned at the backward angle of 137.60° with respect to the beam axis are shown. On the left-hand side, the shifted and unshifted components of the ${11}_1^{+}\to {10}_1^{+}$ transition are presented, on the right-hand side, the shifted and unshifted components of the ${12}_1^{+}\to {10}_1^{+}$ transition are shown.

Figure 3

Experimentally determined and theoretically calculated $B(E2)$ and $B(M1)$ transition strengths in chiral candidate bands of ${}^{134}\mathrm{Pr}$. In the upper panels experimental $B(E2)$ and $B(M1)$ values for transitions in Band 1 and Band 2 are presented. In the second row, the results of TQPTR calculations are displayed. In the panels on the bottom the predictions of the IBFFM are presented.