Model independent reconstruction of impact parameter distributions for intermediate energy heavy ion collisions

Abstract

We present a model-independent method to reconstruct the impact parameter distributions of experimental data for intermediate energy heavy ion collisions, adapted from a recently proposed approach for ultra-relativistic heavy ion collisions. The method takes into account the fluctuations which are inherent to the relationship between any experimental observable and the impact parameter in this energy range. We apply the method to the very large dataset on heavy ion collisions in the energy range 20-100 MeV/nucleon obtained with the INDRA multidetector since 1993, for two observables which are the most commonly used for the estimation of impact parameters in this energy range. The mean impact parameters deduced with this new method for "central" collisions selected using typical observable cuts are shown to be significantly larger than those found when fluctuations are neglected, and as expected the difference increases as bombarding energy decreases. In addition, we will show that this new approach may provide previously inaccessible experimental constraints for transport models, such as an estimation of the extrapolated mean value of experimental observables for b = 0 collisions. The ability to give more realistic, model-independent, estimations of the impact parameters associated to different experimental datasets should improve the pertinence of comparisons with transport model calculations which are essential to better constrain the equation of state of nuclear matter.

14 pages, 7 figures. Revised version accepted for publication in Physical Review C

References in corpus (23)

• GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
• Transport-theoretical Description of Nuclear Reactions
• Nuclear Matter and its Role in Supernovae, Neutron Stars and Compact Object Binary Mergers
• A systematic description of evaporation spectra for light and heavy compound nuclei
• Understanding transport simulations of heavy-ion collisions at 100 and 400 AMeV: Comparison of heavy ion transport codes under controlled conditions
• Unified description of fission in fusion and spallation reactions
• Comparison of heavy-ion transport simulations: Collision integral in a box
• Directed and elliptic flow in Au + Au at intermediate energies
• Bifurcations in Boltzmann-Langevin One Body dynamics for fermionic systems
• Unified Description of Nuclear Stopping in Central Heavy-ion Collision from 10$A$ MeV to 1.2$A$ GeV
• Multifragmentation process for different mass asymmetry in the entrance channel around the Fermi energy
• Relating centrality to impact parameter in nucleus-nucleus collisions
• Measurements of sideward flow around the balance energy
• Model-independent tracking of criticality signals in nuclear multifragmentation data
• Transition from participant to spectator fragmentation in Au+Au reaction between 60 AMeV and 150 AMeV
• Isospin diffusion in semi-peripheral ${}^{58}Ni$ + ${}^{197}Au$ collisions at intermediate energies (I): Experimental results
• Reconstructing the impact parameter of proton-nucleus and nucleus-nucleus collisions
• Full distribution of clusters with universal couplings and in-medium effects
• Investigation of collective radial expansion and stopping in heavy ion collisions at Fermi energies
• Bimodality - a general feature of heavy ion reactions
• Impact parameter smearing effects on isospin sensitive observables in heavy ion collisions
• One-body Langevin dynamics in heavy-ion collisions at intermediate energies
• Study and validation of a new "3D Calorimetry" of hot nuclei with the HIPSE event generator