@article{oai:repo.qst.go.jp:00076014,
 author = {Asai, Takafumi and Kanasaki, Masato and Jinno, Satoshi and Kitagawa, Nobuko and Shutoh, Nobumichi and Kodaira, Satoshi and Yamauchi, Tomoya and Oda, Keiji and Morishima, Kunihiro and Fukuda, Yuuji and Takafumi, Asai and Satoshi, Kodaira and Yuji, Fukuda},
 journal = {High Energy Density Physics},
 month = {Apr},
 note = {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.},
 pages = {44--50},
 title = {Application of nuclear emulsions for the identification of multi-MeV protons in laser ion acceleration experiments},
 volume = {32},
 year = {2019}
}