[en] In a series of ⁴⁸Ti bombardments of ¹⁴⁴Sm the decay energy of the ¹⁸⁹Bi^m πs_1/2α transition that proceeds to the πs _1/2 ground state of ¹⁸⁵Tl was measured to be 7.30(4) MeV. This result establishes the excitation energy of ¹⁸⁹Bi^m as ¹⁹⁰(40) keV rather than the adopted 92(10)-keV value. Our data indicate a leveling off in excitation energy at N ∼ 106 for the s_1/2 intruder state in odd-A Bi isotopes rather than a continued drop at that neutron number as inferred by Coenen et al. in their discussion of intruder state systematics in the Pb region

No abstract available

[en] In a series of ⁴⁸Ti bombardments of ¹⁴⁴Sm the decay energy of the ¹⁸⁹Bi^m (πs_1/2) α transition that proceeds to the (πs_1/2) ground state of ¹⁸⁵Tl was measured to be 7.30(4) MeV. This result establishes the excitation energy of ¹⁸⁹Bi^m as 190(40) keV rather than the adopted 92(10)-keV value. Our data indicate a leveling off in excitation energy at N∼106 for the s_1/2 intruder state in the odd-A Bi isotopes rather than a continued drop at that neutron number as inferred by Coenen et al. in their discussion of intruder state systematics in the Pb region. Consequences of this discrepancy for the adopted excitation energy of the πs_1/2 isomer in ¹⁸⁷Bi are discussed

[en] In a series of ⁴⁸Ti bombardments of ¹⁴⁴Sm the decay energy of the ¹⁸⁹Bi^m (πs_1/2) α transition that proceeds to the πs_1/2 ground state of ¹⁸⁵Tl was measured to be 7.30(4) MeV. This result establishes the excitation energy of ¹⁸⁹Bi^m as 190(40) keV rather than the adopted 92(10)-keV value. Our data thus indicate a leveling off in excitation energy at N ∼ 106 for the s_1/2 intruder state in odd-A Bi isotopes

No abstract available

[en] Angular distribution data for α particles emitted in the enhanced decay of on-line oriented neutron deficient isotopes ^189,191,193Bi near mid-shell (N=104) are presented. They give additional support for the recent finding that anisotropic α emission in enhanced decays from near-spherical nuclei is mainly determined by nuclear structure effects. (authors)

[en] Alpha-decay properties of the isotope ¹⁹¹At were investigated for the first time and the decay properties of ¹⁹³At and ¹⁹⁵At were studied with improved accuracy. The nuclei were produced in fusion-evaporation reactions of ⁵⁴Fe and ⁵⁶Fe ions with ¹⁴¹Pr and ¹⁴²Nd targets. The fusion products were separated in-flight using the gas-filled recoil separator RITU and implanted into a position-sensitive silicon detector. The isotopes were identified using position, time and energy correlations between the implants and subsequent alpha decays. New information concerning the low-lying states in the corresponding alpha-decay daughter nuclei ¹⁸⁷Bi, ¹⁸⁹Bi and ¹⁹¹Bi was also gained using alpha-gamma coincidences. (orig.)

[en] The neutron-deficient isotope ¹⁸⁹Bi has been studied at the University of Jyvaeskylae using alpha-decay, isomer and prompt gamma-ray spectroscopy. The structure of ¹⁸⁹Bi can be understood by the coupling of an unpaired proton to the ¹⁸⁸Pb core, in which spherical, prolate, and oblate shapes were found to coexist. Improved data on alpha-decay and prompt gamma-ray spectroscopy have been obtained, giving further insight into the shape coexistence phenomenon in the neutron-deficient lead region

[en] New microsecond isomers in the neutron-deficient isotopes ^189g,190Bi have been identified after in-flight separation by the velocity filter SHIP. The evaporation residues were identified on the basis of delayed recoil- γ/X-ray, recoil- γ/X-ray- α and excitation function measurements. The systematics of the [ π1i _13/2]13/2 ⁺ excited states in the odd-mass Bi nuclei is discussed. (orig.)

[en] This thesis is devoted to the study of very neutron deficient nuclei in the lead region of the nuclear chart and more precisely to the investigation of the single particle states and collective properties of the ^187,189Bi isotopes by gamma-ray spectroscopy. These nuclei were produced via fusion-evaporation reaction induced by a krypton beam on a silver target. In this mass region, the cross section for producing these nuclei are very low, of the order of a few micro-barns, making experimental studies very difficult. The identification of the nuclei was done using the very powerful RDT (Recoil Decay Tagging) technique, based on the selection of the isotopes through their characteristic alpha-particle decays. The experiments were performed at the university of Jyvdskyla (Finland) with the facility combining the gamma-ray spectrometer JUROSPHERE and the magnetic gas-filled separator RITU. Isomeric states were observed in both nuclei and their life-times measured. The systematics of individual proton states in odd-mass bismuth isotopes have been reproduced with a shell model up to 20 neutrons away from the valley of stability. Furthermore, rotational bands, a signature of collective nuclear motion, have been established for the first time in these nuclei. The interpretation of these results led to the conclusion that ^187,189Bi have a prolate shape at low excitation energy, unlike the heavier bismuth isotopes which have been interpreted to have oblate deformation, implying a shape transition in this mass region. Hartree-Fock-Bogolyubov calculations are consistent with the experimental indication of shape coexistence, as seen in the neighbouring even-even lead nuclei. (author)