In nuclear physics, resonance escape probability p {\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 ψ {\displaystyle \psi } , and their sum is p + ψ = 1 {\displaystyle p+\psi =1} [1].