Resonance escape probability

In nuclear physics, resonance escape probability ${\displaystyle p}$ is a probability of that a neutron transits slow down from fission to thermal energies. Otherwise, it is captured by a nuclear resonance, in a process called resonance absorption, and does not produce nuclear fission. The probability of absorption is called resonance factor ${\displaystyle \psi }$, and their sum is ${\displaystyle p+\psi =1}$[1].

While in general the higher is neutron energy, the lower is the probability of absorption, for some energies, called resonance energies, resonance factor is very high. These energies depend on the properties of heavy nuclei. Resonance escape probability is highly determined by heterogeneous geometry of a reactor[1].

Resonance escape probability appears in four factor formula and six factor formula. To compute it, neutron transport theory is used.