Measurement of Prompt Neutron Decay Constant on Uranium-Plutonium Metal Assembly

The prompt neutron decay constant α of the Uranium-Plutonium metal assembly was meas-ured with Rossi-α technique at delay critical and sub-critical conditions,and then α_c is obtained.The relation-ship between α with reactivity and α is analyzed with detector counts reciprocal.The comparison shows that the direct measured result under delay critical condition is 0.835±0.005/μs,which error is 1/6 of that from Rossi-a and extrapolation methods.