Effect of beam emittance on chromatic blur for proton radiography

The process of emittance increase in proton radiography is analyzed. A radiographic system is designed, and based on it the factors affecting emittance increase are studied with theoretical analysis and Monte Carlo simulation. The results show that the extracted emittance from the accelerator is neglectable for high energy proton radiography, and cannot be neglected for medium energy proton radiography. The extracted emittance could be reduced through decreasing the thickness of the diffuser and enhancing the focusing ability of the accelerator's extraction system. (authors)