Abstract
Neutron induced total reaction cross-sections for various nuclei have a serious mystery. At the low
incident energies, the cross sections fall off to zero. This behavior contradicted the naive expectation based on
the nature of nuclear 2-body forces and had been a mystery for many years. For solving this mystery, we
incorporated the quantum condition that the excited states are sparse in the low-energy region into the
Internuclear Cascade model. As a result, the model incorporating this quantum condition successfully
reproduced the experimental results and solved a long-standing mystery. This quantum condition is absolutely
essential for neutron injection, but it is increasingly being confirmed that it is necessary for other projectiles as
well.
