Direct cross-section measurement of the weak r-process 88Sr(α,n)91Zr reaction in ν-driven winds of core collapse supernovae
arxiv(2024)
摘要
About half of the heavy elements beyond iron are known to be produced by the
rapid neutron capture process, known as r-process. However, the astrophysical
site producing the r-process is still uncertain. Chemical abundances observed
in several cosmic sites indicate that different mechanisms should be at play.
For instance, the abundances around silver measured in a subset of metal-poor
stars indicate the presence of a weak r-process. This process may be active in
neutrino-driven winds of core collapse supernovae where (α,n)
reactions dominate the synthesis of Z 40 elements in the expelled materials.
Scarcely measured, the rates of (α,n) reactions are determined from
statistical Hauser-Feshbach calculations with α-optical-model
potentials, which are still poorly constrained. The uncertainties of the
(α,n) reaction rates therefore make a significant contribution to the
uncertainties of the abundances determined from stellar modeling. In this work,
the ^88Sr(α,n)^91Zr reaction which impacts the weak r-process
abundances has been probed at astrophysics energy for the first time; directly
measuring the total cross sections at astrophysical energies of 8.37 - 13.09
MeV in the center of mass (3.8 - 7.5 GK). Two measurements were performed at
ATLAS with the electrically-segmented ionization chamber MUSIC, in inverse
kinematics, while following the active target technique. The cross sections of
this α-induced reaction on ^88Sr, located at the shell closure N =
50, have been found to be lower than expected, by a factor of 3, despite recent
statistical calculations validated by measurements on neighboring nuclei. This
result encourages more experimental investigations of (α,n) reactions,
at N = 50 and towards the neutron-rich side, to further test the predictive
power and reliability of such calculations.
更多查看译文
AI 理解论文
溯源树
样例
生成溯源树,研究论文发展脉络
Chat Paper
正在生成论文摘要