Theoretical calculations for the laser Compton scattering gamma ray photon flux were carried out by taking into account
various parameters;the measured and theoretical net fluxes agreed well with each other.Calculations for the laser alignment accuracies showed that the separation between the electron and laser beam axes and the beam cross angle between them are required to be less than 0.2 mm and 0.2 mrad,respectively,to suppress the reduction of the maximum photon flux in less than 10%. The alignment accuracy we realized was at least 1.0 mm in the parallel displacement and 1.0 mrad in the angle displacement agains the electron beam.We concluded that the optimum laser
focus position for maximizing gamma ray generation can be accurately predicted by the theoretical calculations obtained in
this study.