[en] The neutron deficient ¹²³Ba and ¹²⁵Ba isotopes obtained in the ¹¹⁴Sn(¹²C, 3n)¹²³Ba and ¹¹⁷Sn(¹²C, 4n)¹²⁵Ba reactions have been studied with Ge(Li) detectors. The most intense γ-rays assigned to ¹²⁵Ba were confirmed in experiment performed with mass-separated sources obtained by spallation reaction from CeO₂ (separation of barium fraction) and Ta (direct isobars separation of A=125) targets irradiated with 660 MeV protons. Beta-gamma delayed coincidence has been measured using NE 102 and Ge(Li) detectors. On the basis of gamma intensities and energy sums the decay schemes are proposed for ¹²³Ba and ¹²⁵Ba. (author)

No abstract available

[en] Current results fall into two categories: those problems which are largely completed and are in preparation for journal publication (decay of /sup 201m,g/Po); lifetimes of g/sub 7/2/ intruder states in ¹⁰⁹Ag; orbital electron capture ratios and decay energy of ²⁰⁷Bi and those problems which are in the midst of active or initial investigation (decay of /sup 187m,g/Au, decay of ²⁰¹²⁰³At; decay of ¹²⁵Ba; and IBFA model computations). Results are presented and discussed

No abstract available

[en] Complete text of publication follows. Octupole correlations in atomic nuclei are due to the interaction between orbitals of opposite parity, whose angular momenta differ by 3ℎ, lying in the proximity of the Fermi surface. In general, this situation occurs when the Fermi level is found between an intruder orbital and the normal-parity subshell. Experimental fingerprints of octupole correlations, such as alternate-parity bands linked by enhanced E1 transitions, very collective E3 transitions, and parity doublets in odd nuclei, are in fact long established in the proximity of both the double octupole shell closures Z = 56, N = 88 (corresponding to the nucleus ¹⁴⁴Ba) and Z = 56, N = 56 (corresponding to the so far unidentified-and perhaps unbound-nucleus ¹¹²Ba). Octupole features of Ba nuclei situated between these two regions were studied. The γ decay of the nuclei ^124,125Ba has been investigated by means of the EUROBALL spectrometer, coupled to the DIAMANT array of charged-particle detectors, using the reaction ⁶⁴Ni+⁶⁴Ni at E_beam = 255 and 261 MeV. In the nucleus ¹²⁵Ba six new E1 transitions have been found to link opposite-parity bands currently interpreted as μd_5/2(+g_7/2), μh_11/2 structures. The previously unknown J^π = 3^- level in the nucleus ¹²⁴Ba has also been identified; its excitation energy is accurately reproduced by a microscopic calculation including octupole correlations. Both issues are bolstered by sizable B(E1)/B(E2) ratios. (author)

[en] The level properties in the low energy region of ^125,127Ba were studied through the decays of ^125,127La by using the JAERI on-line mass separator (JAERI-ISOL). The half-lives of the excited states and the internal conversion coefficients were determined for the first time by the β-γ delayed coincidence technique and by conversion electron measurements, respectively. The half-life of the long-lived isomeric state of ¹²⁷Ba (1.93 s) was determined by spectrum multiscaling measurements. Although the detailed decay schemes have been proposed, no evidence of a parity doublet has been observed. The level properties with respect to the transition probabilities are well interpreted by the Nilsson model

[en] The γ decay of the nuclei ^124,125Ba has been investigated with the EUROBALL array, using the reaction ⁶⁴Ni+⁶⁴Ni at E_beam = 255 and 261 MeV. Six new E1 transitions have been found in the nucleus ¹²⁵Ba, suggesting a significant role of octupole correlations in the origin of its parity doublets. The J^π = 3^- level of the nucleus ¹²⁴Ba has been identified for the first time. Its excitation energy is in very good agreement with a prediction based on a microscopic model including octupole interactions

[en] The high spin states of ¹²⁵Ba populated via the ¹⁰⁹Ag(¹⁹F, 3n) reaction are measured by using a BGO Compton suppressed HPGe detector array. The negative and positive parity bands built respectively on the h_11/2 and g_7/2 neutron hole states are extended to 35/2^- and 23/2⁺. Backbending occurs in both signature branches of the negative band at the frequencies close to that of the ¹²⁴Ba yrast band. An onset of backbending in the positive band has been seen

[en] High-spin levels in ¹²⁵Ba have been produced in the ¹¹⁶Sn(¹²C,3n) reaction and studied by in-beam spectroscopic methods. Two strongly populated band structures are observed. The odd-parity one is based on a 7/2^- state and can be explained as the result of the coupling between an hsub(11/2) neutron-hole and a prolate type triaxial core. The even-parity band, built on a 7/2⁺ state, corresponds to collective excitations associated with a neutron-hole in the gsub(7/2) shell. Comparisons with heavier odd-A Ba isotopes and discussions are made in the framework of the triaxial core model

No abstract available