Delayed Neutron Emission Probability Measurements

摘要

Some neutrons are emitted from fission fragments several seconds to several minutes after fission occurs. These delayed neutrons play a key role for the conduct and in safety aspects of nuclear reactors [1]. But the probabilities to emit such neutrons (P_n) are not well known. A summary of different database and compilation of P_n values is presented to show these discrepancies and uncertainties. Experiments are carried out at the Lohengrin mass spectrometer (at Institut Laue Langevin in Grenoble) and at the ISOLDE facility (CERN) in order to measure some P_n values. Two different techniques are used: either by using gamma-rays detection or neutron emission detection. These two techniques and some preliminary results are presented.