Short timescale behavior of colliding heavy nuclei at intermediate energies

Abstract

An Antisymmetrized Molecular Dynamics model is used to explore the collision of ${}^{114}$Cd projectiles with ${}^{92}$Mo target nuclei at E/A=50 MeV over a broad range in impact parameter. The atomic number (Z), velocity, and emission pattern of the reaction products are examined as a function of the impact parameter and the cluster recognition time. The non-central collisions are found to be essentially binary in character resulting in the formation of an excited projectile-like fragment (PLF${}^{\ast }$) and target-like fragment (TLF${}^{\ast }$). The decay of these fragments occurs on a short timescale, 100$\le$t$\le$300 fm/c. The average excitation energy deduced for the PLF${}^{\ast }$ and TLF${}^{\ast }$ `saturates for mid-central collisions, 3.5$\le$b$\le$6 fm, with its magnitude depending on the cluster recognition time. For short cluster recognition times (t=150 fm/c), an average excitation energy as high as $\approx$6 MeV is predicted. Short timescale emission leads to a loss of initial correlations and results in features such as an anisotropic emission pattern of both IMFs and alpha particles emitted from the PLF${}^{\ast }$ and TLF${}^{\ast }$ in peripheral collisions.

19 pages, 17 figures