  The radiation and ionization energy loss are presented for single arm Monte
Carlo simulation for the GDH sum rule experiment in Hall-A at Jefferson Lab.
Radiation and ionization energy loss are discussed for $^{12}C$ elastic
scattering simulation. The relative momentum ratio $\frac{\Delta p}{p}$ and
$^{12}C$ elastic cross section are compared without and with Radiation Energy
Loss and a reasonable shape is obtained by the simulation. The total energy
loss distribution is obtained, showing a Landau shape for $^{12}C$ elastic
scattering. This simulation work will give good support for radiation
correction analysis of the GDH sum rule experiment.
