Experimental Study of β-delayed Neutron Emission Probability

β-delayed neutron emission is a very important decay mode for neutron-rich unstable nuclei. The branching ratio of delayed neutron in β decay, i.e. the β-delayed neutron emission probability (Pn) plays an important role in nuclear structure, nuclear astrophysics and nuclear energy applications. In the operation of a nuclear reactor, the β-delayed neutron is the crucial factor enabling a chain reaction of nuclear fuel to be controllable. Precise Pn values thus have significant impacts on the safety control of nuclear reactors, the reactor decay heat release, and nuclear waste management as well. Pn is also an indispensable input for network calculation of the rapid-neutron process (r-process) in nuclear astrophysics, which influences on the route of r-process and the final abundance distribution. With the rapid advance of large-scale domestic and international radioactive ion beam facilities toward to very neutron-rich isotopes far from the stability line, experimental measurement of their Pn values is becoming a highlighted topic in nuclear research frontier. This paper briefly introduces the current research status of β-delayed neutron emission probability and the measurement methods. Based on the existing international 3He neutron detector arrays, a design of our own Long Helium-3 Neutron Array (LHENA) is performed to conduct Pn experimental research at domestic radioactive isotope facilities.