Comparison between Proton Radiography Images Using a High-power Femtosecond Laser and a Tandem Van de Graaff Accelerator

Abstract

We performed two experiments of proton radiography by using protons generated by a femtosecond laser and by a Tandem Van de Graaff accelerator to compare their image characteristics. In the laser experiment, the maximum energy of the protons was about 1.8 MeV, and they had a broad energy distribution. The protons in the accelerator experiment were monoenergetic with an energy of 1.8 MeV. In order to evaluate the radiography images, we used a step wedge phantom and a character-type phantom. A CR-39 solid state nuclear track detector (SSNTD) was used as a radiography screen. The radiography images were obtained by using an optical microscope. As a result of the comparison and evaluation of the two experiments' radiography images, protons from the femtosecond laser were found to be more useful than protons from the accelerator. If good proton radiography images are to be obtained using CR-39, utilizing a certain proton energy distribution rather than monoenergetic protons is efficient.