Decays of 143La and 145Ce using KUR-ISOL

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.)