Timescales of Quantum Equilibration, Dissipation and Fluctuation in Nuclear Collisions

• Published in: Physical review letters Vol. 124; no. 21; pp. 1 - 212504
• Main Authors: Simenel, C., Godbey, K., Umar, A. S.
• Format: Journal Article
• Language: English
• Published: College Park American Physical Society 29-05-2020; American Physical Society (APS)
• Subjects: Angular momentum; Balancing; Collisions; equilibration; Fragments; Kinetic energy; NUCLEAR PHYSICS AND RADIATION PHYSICS; Nuclei (nuclear physics); Protons; quasifission; TDHF; Time dependence; timescales
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/PhysRevLett.124.212504

Understanding the dynamics of equilibration processes in quantum systems as well as their interplay with dissipation and fluctuation is a major challenge in quantum many-body theory. The timescales of such processes are investigated in collisions of atomic nuclei using fully microscopic approaches. Results from time-dependent Hartree-Fock and time-dependent random-phase approximation calculations are compared for 13 systems over a broad range of energies. The timescale for full mass equilibration (∼2×10−20  s) is found to be much larger than timescales for neutron-to-proton equilibration, kinetic energy, and angular momentum dissipations which are on the order of 10−21  s. Fluctuations of mass numbers in the fragments and correlations between their neutron and proton numbers build up within only a few 10−21 s. This indicates that dissipation is basically not impacted by mass equilibration, but is mostly driven by the exchange of nucleons between the fragments.