Constraining the Neutron Capture Rate for <sup>90</sup>Sr through β-Decay into the Short-Lived <sup>91</sup>Sr Nucleus
ORAL
Abstract
The slow (s) and rapid (r) neutron capture processes have long been considered to produce nearly the entirety of elements above Fe, but when comparing their yields with spectroscopic data, inconsistencies in abundance arise in the Z=40 region. These differences are expected to be attributable to the intermediate (i) neutron capture process.
Working in weak i-process neutron densities on the order of 1013 neutrons/cm3, the 90Sr(n,γ)91Sr capture reaction has a negative correlation to the production of Zr, possibly explaining the discrepancy between the observed and predicted elemental abundances of Zr in i-process environments such as CEMP-i stars.
I will discuss the β-Oslo analysis of 91Sr to reduce uncertainties in the 90Sr(n,γ)91Sr reaction, measured via the β-decay of 91Rb into 91Sr with the SuN total absorption spectrometer at the NSCL in 2018. By measuring both γ-ray and excitation energies, a coincidence matrix was produced to perform the Oslo analysis, providing experimental information on the Nuclear Level Density (NLD) and γ-ray Strength Functions (γSF), two critical components in limiting the uncertainty of the neutron capture cross section when it cannot be directly measured. This constrained uncertainty will allow us to better characterize the contribution of 90Sr to the i process and make progress in explaining observed abundances in suspected i-process stellar environments.
Working in weak i-process neutron densities on the order of 1013 neutrons/cm3, the 90Sr(n,γ)91Sr capture reaction has a negative correlation to the production of Zr, possibly explaining the discrepancy between the observed and predicted elemental abundances of Zr in i-process environments such as CEMP-i stars.
I will discuss the β-Oslo analysis of 91Sr to reduce uncertainties in the 90Sr(n,γ)91Sr reaction, measured via the β-decay of 91Rb into 91Sr with the SuN total absorption spectrometer at the NSCL in 2018. By measuring both γ-ray and excitation energies, a coincidence matrix was produced to perform the Oslo analysis, providing experimental information on the Nuclear Level Density (NLD) and γ-ray Strength Functions (γSF), two critical components in limiting the uncertainty of the neutron capture cross section when it cannot be directly measured. This constrained uncertainty will allow us to better characterize the contribution of 90Sr to the i process and make progress in explaining observed abundances in suspected i-process stellar environments.
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Presenters
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Beau Greaves
- Univ of Guelph