Design of the stacked CR-39 energy spectrometer for laser-accelerated protons exceeding 100 MeV from micron-size hydrogen cluster targets

In the present study, to measure the precise energy spectrum of laser-accelerated protons, we have designed the stacked detector using HARZLAS (TD-1) and energy moderators. As the energy moderator, we have applied polytetrafluoroethylene (PTFE), because the PTFE is the densest plastic material with smaller cross section of photonuclear reactions than metal materials. Particle and Heavy Ion Transport Code System (PHITS), which is the Monte Carlo simulation code, has been used for the optimization of the thickness of energy moderator. The thickness of PTFE has been determined as 1.8 mm to avoid a 20 MeV proton entering into the second layer. Therefore, the repetition of 0.9mm thick HARZLAS(TD-1) and 1.8 mm thick PTFE can obtain the accurate energy spectrum of laser-accelerated protons. In order to confirm the capability of the designed stacked detector, we have reconstructed the model energy spectrum in the PHITS code simulation. Figure 1 shows the comparison between the model spectrum and the calculated spectrum. From the results of this simulation, the obtained energy spectrum almost reconstructed the model energy spectrum. Thus, the designed stacked detector can be applied to laser-driven ion acceleration as the energy spectrometer for laser-accelerated protons.27th International Conference on Nuclear Tracks and Radiation Measurement