Radiative neutron capture reaction rates for nucleosynthesis: The creation of the first r-process peak

Abstract

About half of the elements beyond iron are synthesized in stars by rapid-neutron capture process (r-process). The stellar environment provides very high neutron flux in a short time ($\sim$ seconds) which is conducive for the creation of progressively neutron-rich nuclei till the waiting point is reached after which no further neutron capture reactions proceed. At this point such extremely neutron-rich nuclei become stable via $\beta^-$ decay. A detailed understanding of the r-process remains illusive. In the present work, we explore the radiative neutron-capture (n,$\gamma$) cross sections and reaction rates around the r-process peak near mass number eighty. The inherent uncertainties remain large in some cases, particularly in case of neutron-rich nuclei. When the low-energy enhancement exists, it results in significant increase in the reaction rate for neutron-capture.