Experimental upper limit for a γ branch from the²³⁶U shape isomer

Abstract

Delayed gamma -particle coincidences following the reaction 235U(d,p)236U at Ed=11 MeV were recorded in order to search for a gamma decay of the 236U( tau =165 ns) shape isomer. An experimental upper limit was determined for the branching ratio ranging from Gamma gamma / Gamma f<4.5 at Egamma =0.5 MeV to gamma gamma / Gamma f<1.5 at Egamma =2.5 MeV for a single gamma cascade. This result for 236U appears to be at variance with the observed gamma branching intensity of the 238U shape isomer.