Projectile Fragmentation of $^{86}$Kr at 64 MeV/nucleon

TL;DR

This study measured fragmentation cross sections of $^{86}$Kr at 64 MeV/nucleon on Be and Ta targets, revealing discrepancies with existing models and highlighting the need for nuclear property data for accurate predictions of neutron-rich isotope production.

Contribution

It provides new experimental cross section data for $^{86}$Kr fragmentation and evaluates the limitations of current empirical models like EPAX for predicting neutron-rich isotope production.

Findings

EPAX overestimates production of neutron-rich isotopes

Cross-section ratios vary with fragment mass, contrary to simple models

Adjusting EPAX parameters did not improve prediction accuracy

Abstract

We measured fragmentation cross sections produced using the primary beam of $^{86}$Kr at 64 MeV/nucleon on $^9$Be and $^{181}$Ta targets. The cross sections were obtained by integrating the momentum distributions of isotopes with 25<Z<36 measured using the RIPS fragment separator at RIKEN. The cross-section ratios obtained with the $^{181}$Ta and $^{9}$Be targets depend on the fragment masses, contrary to the simple geometrical models. We compared the extracted cross sections to EPAX; an empirical parameterization of fragmentation cross sections. Predictions from current EPAX parameterization severely overestimate the production cross sections of very neutron-rich isotopes. Attempts to obtain another set of EPAX parameters specific to the reaction studied here, to extrapolate the neutron-rich nuclei more accurately have not been very successful, suggesting that accurate predictions of production cross sections of nuclei far from the valley of stability require information of nuclear properties which are not present in EPAX.