β-Delayed Proton Decays of ¹⁴⁰Tb and ¹⁴¹Dy as Well as the Spin and Parity of ¹⁴³Dy

Abstract: ¹⁴⁰Tb and ¹⁴¹Dy were produced via fusion evaporation in the reaction ⁴⁰Ca+¹⁰⁶Cd. Their β-delayed proton decays were studied by means of “p-γ” coincidence in combination with a He-jet tape transport system, including half-lives, proton energy spectra, γ-transitions following the proton emissions, and the branching ratios to the low-lying states in the grand-daughter nuclei. The ground-state spins and parities of 140Tb and 141Dy were extracted as 7^± and 9/2^±, respectively, by fitting the experimental data with a statistical model calculation. The configuration-constrained nuclear potential energy surfaces (NPES) of ¹⁴⁰Tb and ¹⁴¹Dy were calculated by using the Woods-Saxon Strutinsky method, which indicate the ground-state spins and parities of ¹⁴⁰Tb and ¹⁴¹Dy to be 7⁺and 9/2^－, respectively. In addition, the configuration-constrained NPES of ¹⁴³Dy was also calculated by using the same method. From the NPES a 1/2⁺ ground state and a 11/2^－ isomer with the excitation energy of 198keV were found. The calculated results are consistent with our experimental data on the decay of ¹⁴³Dy reported in Eur. Phys. J., 2003, A16: 347—351.