$^{18}$O($p$,$\gamma$)$^{19}$F resonance strength measurement at low energies

ORAL

Abstract

As a 0.4M$_{\bigodot}$ $\leq$ M $\leq$ 8M$_{\bigodot}$ approaches the end of its stellar evolution, it will enter the asymptotic giant branch (AGB) stage and ascend the giant branch one final time. During the AGB stage, a star experiences significant mass loss, and grain condensation occurs in the stellar atmosphere. A subset of presolar oxide grains recovered from comet and meteorite samples can be attributed to this stellar environment; these grains feature $^{18}$O depletion that cannot be explained by existing AGB stellar models. An extra mixing process referred to as ``cool bottom processing" (CBP) was proposed by Wasserburg et al. (1995) for low-mass AGB stars. The $^{18}$O depletion observed in these presolar grains may result from the $^{18}$O+$p$ process during CBP. A low energy, unobserved, narrow resonance exists within the ($p$,$\gamma$) reaction that may affect thermonuclear reaction rates near the CBP temperature regime. Though the E$_{R}^{lab}$ = 95 keV resonance strength ($\omega\gamma$) has been constrained previously, measurements at the Laboratory for Experimental Nuclear Astrophysics (LENA) have improved the resonance strength upper limit. The effect this improvement has on $^{18}$O($p$,$\gamma$)$^{19}$F thermonuclear reaction rates will be discussed.

*This work was supported in part by the US Department of Energy under Contract no. DE-FG02-97ER41041. Additional support was provided for M. Q. Buckner by the DOE NNSA Stewardship Science Graduate Fellowship under Grant no. DE-FC52-08NA28752.

Authors

  • Matthew Buckner

    • TUNL, UNC
  • Christian Iliadis

    • The University of North Carolina
    • TUNL, UNC
  • John Cesaratto

    • TUNL, UNC
  • Chris Howard

    • TUNL, UNC
  • Thomas Clegg

    • TUNL, UNC
  • Arthur Champagne

    • The University of North Carolina
    • TUNL, UNC
  • Stephen Daigle

    • TUNL, UNC