Distributions of neutron yields and doses around a water phantom bombarded with 290-MeV/nucleon and 430-MeV/nucleon carbon ions

Satoh, Daiki   ; Kajimoto, Tsuyoshi*; Shigyo, Nobuhiro*; Itashiki, Yutaro*; Imabayashi, Yoichi*; Koba, Yusuke*; Matsufuji, Naruhiro*; Sanami, Toshiya*; Nakao, Noriaki*; Uozumi, Yusuke*

Double-differential neutron yields from a water phantom bombarded with 290-MeV/nucleon and 430-MeV/nucleon carbon ions were measured at emission angles of 15, 30, 45, 60, 75, and 90 using the neutron-detection system constituting of liquid organic scintillators. The angular distributions of neutron yields and effective doses around the phantom were obtained by integrating the double-differential neutron yields and applying the fluence-to-effective dose conversion coefficients. The experimental data were compared with results of the Monte-Carlo simulation code PHITS. The PHITS results showed good agreement with the measured data. From the results, we concluded that the PHITS simulation is applicable to the dose estimation at carbon-therapy facilities.