Probing r-process production of nuclei beyond ²⁰⁹Bi with gamma rays

We estimate gamma-ray fluxes due to the decay of nuclei beyond ²⁰⁹Bi from a supernova or a supernova remnant assuming that the r-process occurs in supernovae. We find that a detector with a sensitivity of ∼10^-7 γ cm^-2 s^-1 at energies from ∼40 keV to ∼3 MeV may detect fluxes due to the decay of ²²⁶Ra, ²²⁹Th, ²⁴¹Am, ²⁴³Am, ²⁴⁹Cf, and ²⁵¹Cf in the newly discovered supernova remnant near Vela. In addition, such a detector may detect fluxes due to the decay of ²²⁷Ac and ²²⁸Ra produced in a future supernova at a distance of ∼1 kpc. Because nuclei with mass numbers A > 209 are produced solely by the r-process, such detections are the best proof for a supernova r-process site. Further, they provide the most direct information on yields of progenitor nuclei with A > 209 at r-process freeze-out. Finally, detection of fluxes due to the decay of r-process nuclei over a range of masses from a supernova or a supernova remnant provides the opportunity to compare yields in a single supernova event with the solar r-process abundance pattern.