高速中性子照射の反跳効果を利用したSr-85を内包した金属フラーレンの生成に関する研究

Synthesis of endohedral 85-Sr metallofullerene by nuclear recoil using high energy neutron

宮下 由香*; 秋山 和彦*; 初川 雄一; 只井 智浩*; 千葉 和喜*; 佐藤 祐太*; 久冨木 志郎*

Miyashita, Yuka*; Akiyama, Kazuhiko*; Hatsukawa, Yuichi; Tadai, Tomohiro*; Chiba, Kazuki*; Sato, Yuta*; Kubuki, Shiro*

高い比放射能を持つ放射性金属内包フラーレンを得るため、これまで核反応の反跳効果を利用した多くの実験が行われてきた。しかし荷電粒子核反応を用いた場合標的フラーレン分子への放射線損傷が大きく金蔵内包フラーレンの生成率は極めて小さいことが知られている。一方高速中性子核反応では直接フラーレンケージを構成する炭素原子核に衝突する際の損傷のみを考慮すればよく、より効率的に放射性金属内包フラーレンの生成が期待される。本研究では14MeVの高速中性子によるSr(n,2n)Sr反応の反跳効果を用いてSr@Cの生成を試みた。標的とするストロンチウム塩としてそれぞれ密度の異なるSr(NO)(2.99g/cm)とSrCO(2.08g/cm)を用いてSr@Cの生成率を評価した。

To obtain an endohedral metallofullerenes with high specific radioactivity using nuclear recoil phenomena, many experiments have been performed so far. However, production yield of metallofullerene by nuclear recoil using high LET radiation was found to be very small because radiation damages to targeted fullerene molecule were not negligible. In order to increase the yield of radioactive metallofullerenes, it is very promising to employ the recoil of nuclear reaction by fast neutron from the viewpoint of reducing the radiation damage. In this session, we will report the synthesis of Sr@C using nuclear recoil of Sr (n,2n) Sr reaction by 14 MeV fast neutron. Mixture of C with strontium salts such as Sr(NO) and SrCO were employed for the target materials. These samples were irradiated by fast neutron in Fusion Neutronics Source at Japan Atomic Energy Agency. After the irradiation, CS, aniline, and HCl were passed through the irradiated samples on the filter to dissolve C, Sr@C, and strontium salts, respectively. The -ray from these solutions were measured by Ge detector. As a result, about 0.75% of radioactivity was observed in the aniline solution from SrCO sample. This result strongly suggests that Sr@C was efficiently produced by fast neutron irradiation of SrCO/C target.