Low Energy measurement of the ${}^{96}\mathrm{Zr}(\alpha ,n{)}^{99}\mathrm{Mo}$ reaction cross section and its impact on weak r-process nucleosynthesis

Abstract

Lighter heavy elements beyond iron and up to around silver can form in neutrino-driven ejecta in core-collapse supernovae and neutron star mergers. Slightly neutron-rich conditions favour a weak r-process that follows a path close to stability. Therefore, the beta decays are slow compared to the expansion time scales, and ($\alpha$,n) reactions become critical to move matter towards heavier nuclei. The rates of these reactions are calculated with the statistical model and their main uncertainty, at energies relevant for the weak r-process, is the $\alpha$+nucleus optical potential. There are several sets of parameters to calculate the $\alpha$+nucleus optical potential leading to large deviations for the reaction rates, exceeding even one order of magnitude. Recently the ${}^{96}$Zr($\alpha$,n)${}^{99}$Mo reaction has been identified as a key reaction that impacts the production of elements from Ru to Cd. Here, we present the first cross section measurement of this reaction at energies (6.22 MeV $\le$ E${}_{c.m.}$ $\le$ 12.47 MeV) relevant for the weak r-process. The new data provide a stringent test of various model predictions which is necessary to improve the precision of the weak r-process network calculations. The strongly reduced reaction rate uncertainty leads to very well-constrained nucleosynthesis yields for $Z=44-48$ isotopes under different neutrino-driven wind conditions.

References in corpus (33)

• GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
• Electromagnetic Counterparts of Compact Object Mergers Powered by the Radioactive Decay of R-process Nuclei
• Astrophysical Reaction Rates From Statistical Model Calculations
• Nucleosynthesis in neutrino-driven winds: I. The physical conditions
• Galactic Evolution of Sr, Y, Zr: A Multiplicity of Nucleosynthetic Processes
• Magnetorotationally driven Supernovae as the origin of early galaxy $r$-process elements?
• Identification of strontium in the merger of two neutron stars
• Electron-capture supernovae as the origin of elements beyond iron
• Neutron Star Mergers Might not be the Only Source of r-Process Elements in the Milky Way
• Production of Light Element Primary Process nuclei in neutrino-driven winds
• STARLIB: A Next-Generation Reaction-Rate Library for Nuclear Astrophysics
• The intermediate r-process in core-collapse supernovae driven by the magneto-rotational instability
• From Nuclei to the Cosmos: Tracing Heavy-Element Production with the Oldest Stars
• Nucleosynthesis in the Early Galaxy
• Further explorations of the alpha-particle optical model potential at low energies for the mass range A=45-209
• R-process Nucleosynthesis from Three-Dimensional Magnetorotational Core-Collapse Supernovae
• Neutrino-driven wind simulations and nucleosynthesis of heavy elements
• The Path to Improved Reaction Rates for Astrophysics
• Relevant energy ranges for astrophysical reaction rates
• How many nucleosynthesis processes exist at low metallicity?
• The activation method for cross section measurements in nuclear astrophysics
• Determination of 141Pr(alpha,n)144Pm cross sections at energies of relevance for the astrophysical p-process using the gamma-gamma coincidence method
• Stellar Abundances in the Early Galaxy and Two r-Process Components
• Impact of $(\alpha ,n)$ reactions on weak r-process in neutrino-driven winds
• Successful prediction of total $\alpha$-induced reaction cross sections at astrophysically relevant sub-Coulomb energies using a novel approach
• Nuclear physics uncertainties in neutrino-driven, neutron-rich supernova ejecta
• Nucleosynthesis of elements between Sr and Ag in neutron- and proton-rich neutrino-driven winds
• Investigation of $\alpha$-induced reactions on Sb isotopes relevant to the astrophysical $\gamma$-process
• Survey of astrophysical conditions in neutrino-driven supernova ejecta nucleosynthesis
• Role of ($\alpha$,n) reactions under $r$-process conditions in neutrino-driven winds revisited
• Measurement of the 187Re(α,n)190Ir reaction cross section at sub-Coulomb energies using the Cologne Clover Counting Setup
• alpha-induced reactions on 115In: cross section measurements and statistical model analysis
• Measurement of (alpha,n) reaction cross sections of erbium isotopes for testing astrophysical rate predictions

Cited by in corpus (9)

• Horizons: Nuclear Astrophysics in the 2020s and Beyond
• Constraining nucleosynthesis in neutrino-driven winds: observations, simulations and nuclear physics
• Measurement of the 91Zr(p,gamma)92mNb cross section motivated by type Ia supernova nucleosynthesis
• Optical potential for incident and emitted low-energy $\alpha$ particles. III. Non-statistical processes induced by neutrons on Zr, Nb, and Mo nuclei
• Measurements of the ${}^{96}$Zr($\alpha$,n)${}^{99}$Mo cross section for astrophysics and applications
• Measurement of $\beta$-particles to determine cross sections relevant to the weak r-process
• Bayesian Analysis of the ${}^{86}$Sr$(\alpha ,\alpha )$ Reaction to Constrain the ${}^{86}$Sr$(\alpha ,n)$ Cross Section at Astrophysical Energies
• The total neutron production from the alpha induced reaction on natural Zirconium
• Astrophysical Reaction Rates for Charged-Particle Induced Reactions on Proton-Rich Nuclides