AN ISOMERIC STATE OF Nd$sup 13$$sup 9$

A tantalum target was irradiated with 600-Mev protons on a cyclotron, and a Nd fraction was isolated 4 to 5 hours after thc irradiation. The conversion electron spectrum was taken over an energy region of 15 to 900 kev on a magnetic spectrograph having a resolution of 0.08%. All the conversion electron lines were ascribed to the decay o Nd/sup 139/ (T/sub 1/2/ = 5.5 hrs). On comparing the experimental value with the theoretical values for the difference in energy of the conversion electrons for the 232.5-kev transition, it was established that all the transitions except the 232.5-kev transition occur in the Pr nucleus. It was found that the 232.5-kev transition is of the M4 type. Thus, the existence of an isomeric state of Nd/sup 139*/ with an energy of 232.5 kev can be considered as established. Similar isomeric states exist in the four neighboring isotopes of Te/sup 131/*/, Xe/sup 133*/, f the conversion electrons from the 232.5- and 113.8-kev gamma transitions, it is estimated that only 18% or less of the transitions take place through the isomeric state of Nd/sup 139*/ to the ground state, and most of the disintegrations take place by BETA conversion to excited levels inmore » Pr/sup 139/. (TTT)« less