Decay ofEu145

Abstract

The decay scheme of ${\mathrm{Eu}}^{145}$ was studied by means of the techniques of beta and gamma spectroscopy. The half-life was measured to be 5.93\ifmmode\pm\else\textpm\fi{}0.1 days. Thirty-three gamma transitions were identified by means of NaI and germanium gamma detectors and 180\ifmmode^\circ\else\textdegree\fi{} magnetic spectrometers. Gamma-gamma coincidences were performed using both NaI and germanium detectors. Most of the transitions were incorporated into the decay scheme in a consistent manner. The multipolarity of several gamma transitions was determined from measurement of conversion coefficients, and a positron spectrum containing two branches was observed. The level scheme of ${\mathrm{Sm}}^{145}$ contains a first excited state at 0.895 MeV and a second excited state at 1.437 MeV. Above 1.5 MeV, the level density greatly increases. Levels with both even and odd parities were observed, and the energy between the ground states of ${\mathrm{Eu}}^{145}$ and ${\mathrm{Sm}}^{145}$ was determined to be about 2.75 MeV. Systematics for the first excited states of nuclei with even proton number and a neutron number near 82 are presented.