Isomeric State ofWi181

Abstract

An isomeric state of ${\mathrm{W}}^{181}$ is excited by a ($\gamma , n$) reaction on ${\mathrm{W}}^{182}$ using the x-ray beam of the Iowa State College 75-Mev synchrotron. The energy and half-life of the isomeric state are found to be 366±4 kev and 14.4±0.3 microseconds, respectively. A measurement of the $K$-shell conversion coefficient yields a value of 0.30±0.03. These experimental data suggest that the transition is of mixed multipole order, $28\%E1+72\%M2\mathrm{}$. This assignment is in agreement with the transition probabilities computed from Nilsson's wave functions for the first excited state and the ground state of the ${\mathrm{W}}^{181}$ nucleus.