Blur caused by container in proton radiography

In order to investigate the blur caused by the container in proton radiography, the expression of blurring FWHM of the container was deduced on the base of the multiple Coulomb scattering and the characteristic of the lens imaging system. The results show that the blurring FWHM is proportional to the distance between the object and the container and root mean square of container’s thickness, and inverse proportional to the proton momentum. The front wall and back wall of container will cause the blur. And on the same situation, the container made of aluminum has smaller blur than that of the iron one. The blurring FWHM of aluminum container (radius 200 cm , thickness 5 cm) is 1.30 mm, larger than the object’s. The analytic results agree with the simulation one by MC program.