Important role of three-body repulsive force effect in nuclear reactions

¹ Department of Physics, Osaka City University, Osaka 558-8585, Japan
² RIKEN Nishina Center, RIKEN, Wako, Saitama 351-0198, Japan
³ Physics Section, Tsuru University, Tsuru, Yamanashi 402-8555, Japan

^a e-mail: furumoto@ocunp.hep.osaka-cu.ac.jp
^b e-mail: sakuragi@ocunp.hep.osaka-cu.ac.jp
^c e-mail: yamamoto@tsuru.ac.jp

Abstract

The effect of three-body force (TBF) is studied in nucleus-nucleus elastic scattering on the basis of Brueckner theory for nucleon-nucleon (NN) effective interaction (complex G matrix) in the nuclear matter. A new G matrix called CEG07 proposed recently by the present authors includes the TBF effect and reproduces a realistic saturation curve in the nuclear matter, and is shown to well reproduce proton-nucleus elastic scattering. The microscopic optical potential for nucleus-nucleus system is obtained by folding the G matrix with nucleon density distributions in colliding nuclei. We first analyze the ¹⁶O + ¹⁶O elastic scattering at E/A = 70 MeV in detail. The observed cross sections are nicely reproduced up to the most backward scattering angles only when the TBF effect is included. The effects of the three-body attraction (TBA) and three-body repulsion (TBR) are also analyzed. The TBR contribution has an important role in nucleus-nucleus elastic scattering. The CEG07 G matrix is also tested in the elastic scattering of ¹⁶O by the ¹²C, ²⁸Si and ⁴⁰Ca targets at E/A = 93.9 MeV, and in the elastic scattering of ¹²C by the ¹²C target at E/A = 135 MeV with a great success. The decisive effect of the TBF is clearly seen also in those systems.