Acceleration of background gas ions induced by Coulomb explosion of clusters

Kanasaki, Masato; Jinno, Satoshi*   ; Sakaki, Hironao; Faenov, A.*; Pikuz, T. A.*; Nishiuchi, Mamiko; Kiriyama, Hiromitsu; Kando, Masaki; Kondo, Kiminori; Matsui, Ryutaro; Morishima, Kunihiro*; Scullion, C.*; Smyth, A. G.*; Alonso, A.*; Doria, D.*; Borghesi, M.*; Watanabe, Yukinobu; Oda, Keiji*; Yamauchi, Tomoya*; Kishimoto, Yasuaki; Fukuda, Yuji

In the previous laser-driven ion acceleration experiment using cluster-gas target, we have only focused on the high energy ions with energies of multi-tens of MeV. In order to reveal synergetic interplay between the Coulomb explosion of clusters and the background gas ions, we have measured protons (background gas ions) separately from carbon and oxygen ions (clusters) by using magnetic spectrometer with CR-39 track detectors. We have found that the number of carbon and oxygen ions decrease sharply at 1 MeV/n. On the other hand, the protons show the Maxwell-Boltzmann energy distribution. Based on the experimental results, the acceleration mechanism of background gas ions induced by Coulomb explosion of clusters can be discussed with the help from numerical simulations.