  A statistical theory of light nucleus reaction (STLN) is proposed to describe
both neutron and light charged particle induced nuclear reactions with 1p-shell
light nuclei involved. The dynamic of STLN is described by the unified
Hauser-Feshbach and exciton model, of which the angular momentum and parity
conservations are considered in equilibrium and pre-equilibrium processes. The
Coulomb barriers of the incident and outgoing charged particles, which
seriously influence the open reaction channels, could be reasonably considered
in the incident channel and the different outgoing channels. In kinematics, the
recoiling effects in various emission processes are taken strictly into
account. Taking $^9$Be(p, xn) reaction as an example, we calculate the
double-differential cross sections of outgoing neutrons and charged particles
using PUNF code in the frame of STLN. The calculated results agree very well
with the existing experimental neutron double-differential cross sections at
$E_p=18$ MeV, and indicate that PUNF code is a powerful tool to set up file-6
in the reaction data library for the light charged particle induced nuclear
reactions with 1p-shell light nuclei involved.
