@article{oai:repo.qst.go.jp:00084020,
 author = {Yoshihiro, Hase and Katsuya, Sato and Atsuya, Chiba and Yoshimi, Hirano and Kengo, Moribayashi and Kazumasa, Narumi and Yoshihiro, Hase and Katsuya, Sato and Atsuya, Chiba and Yoshimi, Hirano and Kengo, Moribayashi and Kazumasa, Narumi},
 issue = {3},
 journal = {Quantum Beam Science},
 month = {Aug},
 note = {The unique energy transfer characteristics of swift cluster ions have attracted the attention of many researchers working on the analysis or processing of material surfaces, but the effects on living organisms remain unclear. We irradiated B. subtilis spores with monomer and cluster proton beams and examined their lethality; the 2-MeV H2+ shows a clearly lower lethality than 340-keV H+, even though both have a comparable linear energy transfer. The 2-MeV H2+ dissoci-ates into a pair of 1-MeV H+ by losing the bonding electrons at the target surface. The estimated internuclear distance and the radial dose distribution suggest that the spread of deposited total energy over two areas separated by just several nanometers greatly diminishes beam lethality, and that the energy density in the very center of the trajectory, possibly within a 1-nm radius, has a great impact on lethality. We also performed a whole genome resequencing of the surviv-ing colonies to compare the molecular nature of mutations but failed to find a clear difference in overall characteristics. Our results suggest that cluster beams may be a useful tool for under-standing biological effects of high linear energy transfer radiation.},
 title = {Proton-Cluster-Beam Lethality and Mutagenicity in Bacillus subtilis Spores},
 volume = {5},
 year = {2021}
}