Observation of the 3 evaporation channel in the complete hot-fusion reaction Mg + Cm leading to the new superheavy nuclide Hs

Hot-fusion反応Mg+Cmにおける3蒸発過程の観測; 新しい超重核種Hsの合成

Dvorak, J.*; Brchle, W.*; Chelnokov, M.*; Dllmann, Ch. E.*; Dvorakova, Z.*; Eberhardt, K.*; Jger, E.*; Krcken, R.*; Kuznetsov, A.*; 永目 諭一郎; Nebel, F.*; 西尾 勝久  ; Perego, R.*; Qin, Z.*; Schdel, M.*; Schausten, B.*; Schimpf, E.*; Schuber, R.*; Semchenkov, A.*; Thrle, P.*; Trler, A.*; Wegrzecki, M.*; Wierczinski, B.*; Yakushev, A.*; Yeremin, A.*

Dvorak, J.*; Brchle, W.*; Chelnokov, M.*; Dllmann, Ch. E.*; Dvorakova, Z.*; Eberhardt, K.*; Jger, E.*; Krcken, R.*; Kuznetsov, A.*; Nagame, Yuichiro; Nebel, F.*; Nishio, Katsuhisa; Perego, R.*; Qin, Z.*; Schdel, M.*; Schausten, B.*; Schimpf, E.*; Schuber, R.*; Semchenkov, A.*; Thrle, P.*; Trler, A.*; Wegrzecki, M.*; Wierczinski, B.*; Yakushev, A.*; Yeremin, A.*

Cm+Mg反応で生成する108番元素ハッシウム(Hs)同位体の生成断面積を迅速気相化学分離装置COMPACTを用いて測定した。入射重イオンMgのエネルギーを変化させCm(Mg, )反応の励起関数を求めたところ、比較的軽い重イオンとアクチノイドターゲットを組合せた反応、いわゆるHot-fusion反応での3蒸発過程が初めて観測された。この蒸発過程で生成する新しい超重核種Hsを同定することに成功した。

The analysis of a large body of heavy ion fusion reaction data with medium-heavy projectiles (6Z18) and actinide targets suggests a disappearance of the 3 exit channel with increasing atomic number of the projectile. Here, we report a measurement of the excitation function of the reaction Cm(Mg,)Hs and the observation of the new nuclide Hs produced in the 3 evaporation channel at a beam energy well below the Bass fusion barrier with a cross section comparable to the maxima of the 4 and 5 channels. This indicates the possible discovery of new neutron-rich transactinide nuclei using relatively light heavy ion beams of the most neutron-rich stable isotopes and actinide targets.