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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Nuclear emulsions are applied to identify multi-MeV protons accelerated by an intense PW-class laser. Although nuclear emulsions, which record the three-dimensional trajectories of charged particles, feature high sensitivity and a sub-micron spatial resolution, they have never been used for the detection of laser-accelerated ions. This is because intense laser-matter interactions generate not only ions but also copious electrons, including secondary electrons induced by X-rays, which are recorded as background noise in a nuclear emulsion. Therefore, it is not a trivial task to identify ion tracks in a nuclear emulsion exposed to such extreme mixed radiation elds. Here, for the rst time, we have succeeded in identifying the signals from laser-accelerated protons in nuclear emulsions by suppressing the background noise signals through the use of desensitized development conditions, i.e., a developer solution with a pH of 7.3 and a development time of 25 min. The energy spectrum obtained from a stack of nuclear emulsion lms shows good agreement with that obtained from a stack of lms of the con- ventional solid-state nuclear track detector material CR-39, which is sensitive only to ions. An additional benchmark experiment with 100-MeV protons from a conventional accelerator apparatus con rms that nuclear emulsions have the potential to measure 100-MeV-class laser-accelerated protons.
Application of nuclear emulsions for the identification of multi-MeV protons in laser ion acceleration experiments
