量研学術機関リポジトリ「QST-Repository」は、国立研究開発法人 量子科学技術研究開発機構に所属する職員等が生み出した学術成果(学会誌発表論文、学会発表、研究開発報告書、特許等)を集積しインターネット上で広く公開するサービスです。 Welcome to QST-Repository where we accumulates and discloses the academic research results(Journal Publications, Conference presentation, Research and Development Report, Patent, etc.) of the members of National Institutes for Quantum Science and Technology.
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Laser plasma proton acceleration, where it was recently reported that near-100-MeV proton acceleration was demonstrated, offers the potential to realize a compact and cost-effective accelerator in the future. Because it can generate an extreme electric field that is over six orders of magnitude higher than that of a conventional radio-frequency accelerator apparatus. To understand the underlying physics of the acceleration process and increase maximum proton energy, precise measurement of both the energy spectrum and the two-dimensional distribution is required. Against this background, we have developed a new measurement method for laser-accelerated sub-GeV-class protons using the nuclear emulsion. Based on the Multiple Coulomb Scattering (MCS) method in an Emulsion Cloud Chamber (ECC), which is a stack of nuclear emulsion films and scatterer plates, the incident energies were inversely evaluated by the scattering angle. The proof-of-principle experiment has been conducted with the Heavy-Ion Medical Accelerator in Chiba (HIMAC) to verify that the ECC is able to identify sub-GeV protons with the MCS method. Combined with a technique of machine learning, a new measurement method has been developed to obtain an energy spectrum of laser-accelerated sub-GeV protons by the ECC with the MCS method.