Detection of nuclear-decay γ rays provides a sensitive thermometer of nova nucleosynthesis. The most intense γ-ray flux is thought to be annihilation radiation from the β+ decay of F18, which is destroyed prior to decay by the F18(p,α)O15 reaction. Estimates of F18 production had been uncertain, however, because key near-threshold levels in the compound nucleus, Ne19, had yet to be identified. We report the first measurement of the F19(He3,tγ)Ne19 reaction, in which the placement of two long-sought 3/2+ levels is suggested via triton-γ-γ coincidences. The precise determination of their resonance energies reduces the upper limit of the rate by a factor of 1.5-17 at nova temperatures and reduces the average uncertainty on the nova detection probability by a factor of 2.1.
Publication Source (Journal or Book title)
Physical Review Letters
Hall, M., Bardayan, D., Baugher, T., Lepailleur, A., Pain, S., Ratkiewicz, A., Ahn, S., Allen, J., Anderson, J., Ayangeakaa, A., Blackmon, J., Burcher, S., Carpenter, M., Cha, S., Chae, K., Chipps, K., Cizewski, J., Febbraro, M., Hall, O., Hu, J., Jiang, C., Jones, K., Lee, E., O'Malley, P., Ota, S., Rasco, B., Santiago-Gonzalez, D., Seweryniak, D., Sims, H., Smith, K., Tan, W., Thompson, P., & Thornsberry, C. (2019). Key Ne 19 States Identified Affecting γ-Ray Emission from F 18 in Novae. Physical Review Letters, 122 (5) https://doi.org/10.1103/PhysRevLett.122.052701