Investigation of shape isomeric states in actinides

The γ-decay of the 236U shape isomer at EII=(2.75±0.01) MeV has been observed, as reported last year. The ratio of γ-decay to delayed fission - the competing process - has been determined to ΓFγ/ΓFf=8±3. Four different cascades depopulating the shape isomer are found and investigated in detail. With regard to that, the excitation function and the γ-γ angular correlation are discussed. With the same method it is also possible to search for other shape isomers, e.g. in the thorium isotopes. First results in a 232Th(d,p)233Th experiment show an isomeric state with an excitation energy of EII=2.8 MeV and a halflive of t1/2=17 ns, which might be a good candidate for a shape isomer in 233Th. (orig.)