Speaker
Description
Abstract: X-ray superbursts are powered by runaway thermonuclear burning deep inside the crust of a neutron star, for which the pycnonuclear fusion of neutron-rich isotopes is an important heat source. A major source of uncertainty in models of superbursts stems from nuclear cross sections for the fusion of neutron-rich isotopes, which cannot currently be measured. To help constrain astrophysical models, the $^{16}$C + $^{12,13}$C fusion reaction was measured at Argonne National Laboratory's ATLAS facility. A 220-MeV radioactive beam of 16C was produced by the RAISOR (RAdioactive Ion SeparatOR) facility and delivered with a rate of 1,200 pps and beam purity of 50-80%. The reactions were measured by MUSIC (MUlti-Sampling Ionization Chamber), an active target detector filled with methane or $^{13}$C-enriched methane gas at 400 Torr. The $^{16}$C + $^{12,13}$C cross sections were measured for EC.M. less than and approx. equal to 25 MeV. This is the most neutron-rich carbon fusion system that has been studied experimentally to date. The experimentally measured cross sections for these two fusion reactions and comparisons to current fusion models will be presented. This work is supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under contract number DE-AC02-06CH11357, grant No. DE-FG02-96ER40978, and grant No. DE-SC0026091. This research used resources of ANL's ATLAS facility, which is a DOE Office of Science User Facility.