Does a bypass of the <sup>56</sup>Ni rp-process waiting point exist?
COFFEE_KLATCH · Invited
Abstract
The rp-process path depends heavily on the nuclear properties of proton-rich nuclei as well as the temperature-density trajectory of the X-ray burst. Often, branching points occur when proton captures and β decays have similar time-scales. The canonical rp-process path flows through the major waiting point at 56Ni, but recent work has suggested that, depending on the conditions of the X-ray burst, a bypass can form beginning with the 55Ni(p,γ) reaction. A strong bypass would allow material to move towards heavier nuclei faster, decreasing the A = 55-60 content of the resultant rp-process ashes, altering the thermal structure of the neutron star crust. Experimental work determining the important resonance states in 56Cu as well as the measurement of the previously highly-uncertain 56Cu mass have constrained the 55Ni(p,γ)56Cu rate significantly. Experimental results and rp-process network calculations will be presented to demonstrate the effect of the bypass. Future work aimed at reducing the remaining reaction rate uncertainties will also be presented.
*This work was conducted with the support of Michigan State University, the National Science Foundation under Grants No. PHY-1102511, PHY1713857, PHY10-68217, PHY14-04442, PHY08-22648, and PHY14-30152, as well as by the US Department of Energy, Office of Science, Office of Nuclear Physics under award number DESC0015927. GRETINA was funded by the U.S. DOE Office of Science. Operation of the array at NSCL is supported by NSF under Cooperative Agreement PHY11-02511 (NSCL) and DOE under Grant No. DE-AC02-05CH11231 (LBNL). This work has also been supported by a DAAD P.R.I.M.E. fellowship with funding from the German Federal Ministry of Education and Research and the People Programme (Marie Curie Actions) of the European Unions Seventh Framework Programme FP7/2007/2013) under REA Grant Agreement No. 605728.
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Presenters
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Wei Jia Ong
- Argonne National Laboratory