Very high rotational frequencies and band termination in 73Br

Rotational bands in 73Br have been investigated up to spins of 65/2 using the EUROBALL III spectrometer. One of the negative-parity bands displays the highest rotational frequency 1.85 MeV reported to date in nuclei with mass number greater than 25. At high frequencies, the experimental dynamic moment of inertia for all bands decrease to very low values, indicating a loss of collectivity. The bands are described in the configuration-dependent cranked Nilsson-Strutinsky model. The calculations indicate that one of the negative-parity bands is observed up to its terminating single-particle state at spin 63/2. This result establishes the first band termination case in the A = 70 mass region.Comment: 6 pages, 6 figures, submitted to Phys. Rev. C as a Rapid Communicatio

Lifetime measurements in 80^{80}Br and a new region for observation of chiral electromagnetic selection rules

Level lifetimes for the candidate chiral doublet bands of 80Br were extracted by means of the Doppler-shift attenuation method. The absolute transition probabilities derived from the lifetimes agree well with the M1 and E2 chiral electromagnetic selection rules, and are well reproduced by the triaxial particle rotor model calculations. Such good agreements among the experimental data, selection rules of chiral doublet bands and theoretical calculations are rare and outstanding in researches of nuclear chirality. Besides odd-odd Cs isotopes, odd-odd Br isotopes in the A≈ 80 mass region represent another territory that exhibits the ideal selection rules expected for chiral doublet bands

Absolute E1 and E2 transition rates in 110^{110}Cd

The lifetimes of several states in $^{110}$Cd have been determined by means of the generalized centroid-shift method. The reaction $^{108}$Pd($\alpha$,2n) has been used and the following results were obtained: T$_{1/2}$(2879 keV) $=$ 0.60 $\pm$ 0.10 ns, T$_{1/2}$(3029 keV) $=$ 0.30 $\pm$ 0.10 ns, T$_{1/2}$(3056 keV) $=$ 2.25 $\pm$ 0.10 ns, T$_{1/2}$(3611 keV) $=$ 0.45 $\pm$ 0.10 ns. Electric dipole and quadrupole transitions are discussed in terms of octupole and quadrupole collectivity. The odd-spin sequence of the semi-aligned structure $\nu$(h$_{11/2}$d$_{5/2}$) has been established with the band-head at J$^{\pi}$ $=$ $7^-_2$ identified as a new two-quasiparticle isomer, the lower-lying 5$^-_{1,2}$ states being of two-quasiproton character. to 0pt Nuclear Reaction: $^{108}$Pd($\alpha$,2n), E = 27 MeV,; measured E$_{\gamma}$, I$_{\gamma}$, $\gamma$-r.f. Deduced: T$_{1/2}$, B($\alpha$L) in $^{110}$Cd. Ge detectors. Generalized centroid-shift analysis