Cross-section measurement of 9Be(γ,n)8Be and implications for α+α+n→9Be in the r process


Journal Article

Models of the r process are sensitive to the production rate of 9Be because, in explosive environments rich in neutrons, α(αn,γ) 9Be is the primary mechanism for bridging the stability gaps at A=5 and A=8. The α(αn,γ)9Be reaction represents a two-step process, consisting of α+α→8Be followed by 8Be(n,γ)9Be. We report here on a new absolute cross-section measurement for the 9Be(γ,n)8Be reaction conducted using a highly efficient, 3He-based neutron detector and nearly monoenergetic photon beams, covering energies from Eγ=1.5 MeV to Eγ=5.2 MeV, produced by the High Intensity γ-ray Source of Triangle Universities Nuclear Laboratory. In the astrophysically important threshold energy region, the present cross sections are 40% larger than those found in most previous measurements and are accurate to ±10% (95% confidence). The revised thermonuclear α(αn,γ)9Be reaction rate could have implications for the r process in explosive environments such as type II supernovae. © 2012 American Physical Society.

Full Text

Duke Authors

Cited Authors

  • Arnold, CW; Clegg, TB; Iliadis, C; Karwowski, HJ; Rich, GC; Tompkins, JR; Howell, CR

Published Date

  • April 3, 2012

Published In

Volume / Issue

  • 85 / 4

Electronic International Standard Serial Number (EISSN)

  • 1089-490X

International Standard Serial Number (ISSN)

  • 0556-2813

Digital Object Identifier (DOI)

  • 10.1103/PhysRevC.85.044605

Citation Source

  • Scopus