Fine structure in the α decay of 179Hg and 177Au

AbstraktAbstract

The alpha-decay fine structure of 179Hg and 177Au was studied by means of decay spectroscopy. Two experiments were performed at the Accelerator Laboratory of the University of Jyv & auml;skyl & auml; (JYFL), Finland, utilizing the recoil separator RITU and a digital data acquisition system. The heavy-ion induced fusion-evaporation reactions 3682Kr + 44100Ru and 3888Kr + 4292Mo were used to produce the 179Hg and 177Au nuclei, respectively. Studying the evaporation residues (ER, recoils)-alpha 1-alpha 2 correlations and alpha-gamma coincidences, a new alpha decay with E alpha = 6156(10) keV was observed from 179Hg. This decay populates the (9/2-) excited state at an excitation energy of 131.3(5) keV in 175Pt. The internal conversion coefficient for the 131.3(5) keV transition de-exciting this state was measured for the first time. Regarding the 177Au nucleus, a new alpha decay with E alpha = 5998(9) keV was observed to populate the 156.1(6) keV excited state in 173Ir. Two de-excitation paths were observed from this excited state. Moreover, a new 215.7(13) keV transition was observed to depopulate the 424.4(13) keV excited state in 173Ir. Properties of the 179Hg and 177Au alpha decays were examined in a framework of reduced widths and hindrance factors. For clarity and simplicity, the spin and parity assignments (e.g. J pi) are presented without brackets throughout the text.

The alpha-decay fine structure of 179Hg and 177Au was studied by means of decay spectroscopy. Two experiments were performed at the Accelerator Laboratory of the University of Jyv & auml;skyl & auml; (JYFL), Finland, utilizing the recoil separator RITU and a digital data acquisition system. The heavy-ion induced fusion-evaporation reactions 3682Kr + 44100Ru and 3888Kr + 4292Mo were used to produce the 179Hg and 177Au nuclei, respectively. Studying the evaporation residues (ER, recoils)-alpha 1-alpha 2 correlations and alpha-gamma coincidences, a new alpha decay with E alpha = 6156(10) keV was observed from 179Hg. This decay populates the (9/2-) excited state at an excitation energy of 131.3(5) keV in 175Pt. The internal conversion coefficient for the 131.3(5) keV transition de-exciting this state was measured for the first time. Regarding the 177Au nucleus, a new alpha decay with E alpha = 5998(9) keV was observed to populate the 156.1(6) keV excited state in 173Ir. Two de-excitation paths were observed from this excited state. Moreover, a new 215.7(13) keV transition was observed to depopulate the 424.4(13) keV excited state in 173Ir. Properties of the 179Hg and 177Au alpha decays were examined in a framework of reduced widths and hindrance factors. For clarity and simplicity, the spin and parity assignments (e.g. J pi) are presented without brackets throughout the text.