Radiochemical study of the kinematics of multi-nucleon transfer reactions in Ca + Cm collisions 10% above the Coulomb barrier

クーロンバリヤーを10%超えるエネルギーにおけるCa + Cmの多核子移行反応運動学の放射化学的研究

Gtz, M.*; Gtz, S.*; Kratz, J. V.*; Dllmann, Ch. E.*; Mokry, Ch.*; Runke, J.*; Thrle-Pospiech, P.*; Wiehl, N.*; Schdel, M.; Ballof, J.*; Dorrer, H.*; Grund, J.*; Huber, D.*; Jger, E.*; Keller, O.*; Krier, J.*; Khuyagbaatar, J.*; Lens, L.*; Lommel, B.*; Mendel, M.*; Moody, K. J.*; Scharrer, P.*; Schausten, B.*; Shaughnessy, D. A.*; Schmitt, M.*; Steiner, J.*; Trautmann, N.*; Yakushev, A.*; Yakusheva, V.*

Gtz, M.*; Gtz, S.*; Kratz, J. V.*; Dllmann, Ch. E.*; Mokry, Ch.*; Runke, J.*; Thrle-Pospiech, P.*; Wiehl, N.*; Schdel, M.; Ballof, J.*; Dorrer, H.*; Grund, J.*; Huber, D.*; Jger, E.*; Keller, O.*; Krier, J.*; Khuyagbaatar, J.*; Lens, L.*; Lommel, B.*; Mendel, M.*; Moody, K. J.*; Scharrer, P.*; Schausten, B.*; Shaughnessy, D. A.*; Schmitt, M.*; Steiner, J.*; Trautmann, N.*; Yakushev, A.*; Yakusheva, V.*

Ca + Cmの多核子移行反応の運動学を多層捕集箔法と放射化学分離法を用いて調べた。過去の研究で、生成核の同位体分布の幅が、標的よりも重い同位体より軽い同位体の方が広いことが知られており、標的よりも軽い同位体の方がエネルギーロスの大きな衝突の成分が多いためと解釈されてきた。しかし、本研究で両者の平均的な全運動エネルギー損失、すなわち平均励起エネルギーの大きさが測定され、両者に大きな違いがないことが明らかになった。このことは過去の解釈と矛盾するため、本研究では、高い励起エネルギーを持って生成される標的よりも重い同位体は核分裂によって失われる、という新しい解釈を提案した。

The kinematics of multi-nucleon transfer reactions in the Ca + Cm collisions were investigated using a stacked-foil technique and radiochemical separations. In previous studies, isotopic distributions of the products of below-target isotopes were found to be broader than those of above-target isotopes, which had been interpreted as larger contributions of strongly dumped collisions in the productions of below-target isotopes than above-target ones. However, in the present study, the average total kinetic energy loss (TKEL), and thus, the average excitation energies were determined for both below-target and above-target isotopes, and they were found to be similar. This contradicts the previous interpretation, and thus, a new interpretation has been proposed; highly excited above-target products are lost by fission.