[en] The decay of ¹⁴³La has been investigated. Sources have been obtained from 2 isotope separators (ISERE, OSIRIS). 12 gamma rays, with the most intense at 620keV representing only 1.4% of decay, have been attributed to the ¹⁴³La decay. A level scheme has been found and compared with the one deduced from (d,p) and (n,γ) reactions on ¹⁴²Ce

[en] The decay of mass-separated ¹⁴³Ba to levels in ¹⁴³La has been investigated using γ-ray spectroscopy in both the singles and coincidence modes. Of 69 γ rays ascribed to the decay of ¹⁴³Ba, 59 were placed in a level scheme which represents the first information on excited states in ¹⁴³La. A total of 19 levels up to a maximum energy of 2347 keV were observed. The resulting level scheme is compared with that of ¹⁴¹La and systematics of odd-A La isotopes are discussed

[en] Accurate measurements of beta- and gamma-rays resulting from the decay of ¹⁴³La and ¹⁴⁵Ce are made with KUR-ISOL to develop their decay diagram. First, gamma-singles spectrometry is performed to determine the energy and intensity of gamma-rays resulting from the decay of ¹⁴³La and ¹⁴⁵Ce. About 30 and 7 peaks are newly identified for ¹⁴³La and ¹⁴⁵Ce, respectively, in their gamma-ray spectra. Another gamma-singles spectrometry is carried out using 60 cm³ Ge(Li) and LEPS detectors to determine 620 keV gamma-ray emission rate in the decay of ¹⁴³La. The emission rate is calculated at 4.23 and 4.62 percent from measurements made with Ge(Li) and LEPS, respectively. Gamma-gamma coincidence spectrometry is performed using a 60 cm³Ge(Li)-142 cm³Ge(Li) or a 60 cm³Ge(Li)-LEPS detector. LEPS is then applied to beta-singles spectrometry to determine the maximum energy of the gamma-rays from ¹⁴³La and ¹⁴⁵Ce within an error of about 20 keV. The beta-ray end point is determined from the measurements. Decay diagrams of ¹⁴³La and ¹⁴⁵Ce are constructed based on these results. The intensity and multipolarity of 18.9, 23.4 and 42.3 keV gamma-rays in the decay of ¹⁴³La are determined. Energy and intensity of gamma-rays of 2.8 MeV or above are also determined for ¹⁴³La. Three low energy levels of ¹⁴⁵Ce is examined in comparison to the decay diagram of ¹⁴³La. ¹⁴³Ce is found to have an energy level structure similar to that of other nuclides of N = 85. (Nogami, K.)

[en] A study of the beta decay of ¹⁴³Cs and ¹⁴³Ba fission products was undertalen by the use of two on-line mass-separators OSTIS and OSIRIS. Level schemes for ¹⁴³Ba and ¹⁴³La are deduced from gamma and conversion electron spectra, γ-γ and β-γ coincidences. Qβ values and ground state beta feedings were also measured. The nuclei ¹⁴³La and ¹⁴³Ba are tentavitely inserted in a systematic of odd-even nuclei around A = 143 and even-odd nuclei with 87 neutrons respectively. (orig.)

[en] The structures of odd-even ¹³⁹La, ¹⁴¹La, ¹⁴³La, ¹³⁹Cs, and ¹⁴¹Cs have been investigated by methods of gamma-ray singles, gamma-ray angular correlation, and conversion-electron spectroscopy at the National Bureau of Standards Research Reactor and the Tristan II on-line mass separator at Brookhaven National Laboratory. The systematics of these nuclei and others of the regions are discussed in terms of applicable models. Isotonic and isotopic progressions are also considered

[en] The yrast and near-yrast level scheme of light neutron-rich ¹⁴³La (Z=57, N=86) is reinvestigated and expanded and that of ¹⁴⁴La (N=87) is proposed for the first time by measuring prompt γ rays from the spontaneous fission of ²⁵²Cf at Gammasphere. Spins/parities are assigned to the lowest-lying levels of ^143,144La based on the early studies of β^- decay, and the assignments for high-spin levels of ^143,144La are made by measuring internal conversion coefficients and following the level systematics of the neighboring heavier La isotopes and even-even Ba and Ce nuclei. The B(E1)/B(E2) ratios, energy displacements δE(I) and rotational frequency ratios ω^-(I)/ω⁺(I) of the new parity-doublets of ^143,144La indicate that octupole deformations/correlations also develop in these nuclei. The band-crossings observed in a rotational frequency range of 0.31 to 0.34 MeV for the two even-parity bands in ¹⁴³La but being absent in ¹⁴⁴La are interpreted as due to alignment of a pair of i_13/2 neutrons in ¹⁴³La

[en] The high-spin levels in the neutron-rich ¹⁴³La nucleus have been investigated from the study of prompt γ rays in the spontaneous fission of ²⁵²Cf with the Gammasphere detector array. A new level scheme with spin up to 27/2 h has been established, and the collective bands have been identified for the first time. A set of opposite-parity bands connected by ΔI=1E1 crossing transitions gives evidence for octupole correlations. The results of B(E1)/B(E2) branching ratios indicate that the octupole correlations in ¹⁴³La are strong. The reflection-asymmetry shell model is applied to calculate the levels of the octupole bands of ¹⁴³La, and the calculated results are in good agreement with the experimental ones

[en] γ-singles and γ-γ coincidence measurements have been performed on samples of ¹⁴³La produced in thermal neutron induced fission of ²³⁵U. The nuclide was isolated by means of the on-line chemical separation system SISAK in combination with a gas jet recoil transportation (GJRT) system. From the decay of the strongest γ-lines, the half-life of ¹⁴³La has been determined to be 14.23 +- 0.14 min. A number of new γ-rays are reported, and a decay scheme involving many new levels has been derived. (author)

[en] On-line separations of fission products have up to now been obtained for most of the elements, but some elements, in particular rare earths, have not yet been separated. The off-line separations of rare-earths is reported. The fission products (F.P.) of a 10μg ²⁵²Cf source are stopped in a tantalum foil (10μm). Owing to their kinetic energy the F.P. go a few micrometer inside the tantalum foil. Without treatment, the foil is put directly inside the ion source of the ISERE isotope separator, which has been previously adjusted on the mass. After 10 min of collection, the activity is counted by gamma spectrometry. With this method of collection, the activity is counted by gamma spectrometry. With this method it was possible to study F.P. with half-lives greater than 10 min such as ¹⁴³ La. For lanthanum and cerium better yields were obtained, where the activity has been collected at the mass of the isotope-plus 16 (oxygen), while for europium a better yield was obtained at the mass of the element. (Auth.)

[en] The decay properties of ¹⁴³La and ¹⁴⁷Pr were investigated with Ge(Li), NaI(Tl) and plastic detectors in singles and coincidence modes with the help of a rapid paper electrophoresis. Twenty-three new γ-rays for ¹⁴³La and 9 new transitions for ¹⁴⁷Pr were observed and fairly precise decay schemes for ¹⁴³La including 5 new levels and for ¹⁴⁷Pr including 4 new levels were proposed. The half-lives of ¹⁴³La and ¹⁴⁷Pr are 14.14 +- 0.16 and 13.3 +- 0.4 min, and observed Qsub(β) values for ¹⁴³La and ¹⁴⁷Pr are 3.28 +- 0.10 and 2.77 +- 0.10 MeV, respectively. (author)