LIMITS ON THE HALF-LIFE OF THE SHAPE ISOMER IN U-239

With a neutron-capture experiment the shape isomer in U-239 was sought via delayed gammagamm-coincidences. From the negative result it is co ncluded that the isomeric half life T1/2 is larger than 0.25 mus, and that the intermediate structure in the fission cross section of U- 238 has to be interpreted as prompt fission in contradiction to some theo retical expectations. This leads also to the assumption, that the para metrization of the fission barrier of U-239 in terms of parabolic segm ents is not valid.