Results 1 - 10 of 489
Results 1 - 10 of 489. Search took: 0.09 seconds
|Sort by: date | relevance|
[en] Knowledge of the 17F(p,γ)18Ne reaction rate is important for understanding stellar explosions, but it was uncertain because the properties of an expected but previously unobserved 3+ state in 18Ne were not known. This state would provide a strong s-wave resonance for the 17F+p system and, depending on its excitation energy, could dominate the stellar reaction rate at temperatures above 0.2 GK. We have observed this missing 3+ state by measuring the 1H(17F,p)17F excitation function with a radioactive 17F beam at the ORNL Holifield Radioactive Ion Beam Facility (HRIBF). We find that the state lies at a center-of-mass energy of Er=599.8±1.5stat±2.0sys keV (Ex=4523.7±2.9keV) and has a width of Γ=18±2stat±1syskeV. The measured properties of the resonance are only consistent with a Jπ=3+ assignment
[en] The rate of the 17F(p,γ)18Ne reaction is important in various astrophysical events. A previous 17F(p,p)17F measurement identified a 3+ state providing the strongest resonance contribution, but the resonance strength was unknown. We have directly measured the 17F(p,γ)18Ne reaction using a mixed beam of 17F and 17O at ORNL. The resonance strength for the 3+ resonance in 18Ne was found to be ωγ=33±14(stat)±17(syst) meV, corresponding to a γ width of Γγ=56±24(stat)±30(syst) meV. An upper limit on the direct capture of S(E)≤65 keV b was determined at an energy of 800 keV
[en] The rate of the 17F(p,γ)18Ne reaction is of significant importance in astrophysical events like novae and x-ray bursts. A 3+ state in 18Ne predicted to dominate the rate was found at 599.8 keV using the 17F(p,p)17F reaction , but the resonance strength was unknown. For the first time, the 17F(p,γ)18Ne reaction has been measured directly with the Daresbury Recoil Separator, using a mixed beam of radioactive 17F and stable 17O from the HRIBF at ORNL. A γ width was found for the 599.8 keV resonance in 18Ne, and an upper limit on the direct capture S factor was determined at an intermediate energy of 800 keV.
[en] Many astrophysical events, such as novae and X-ray bursts, are powered by reactions with radioactive nuclei. Studying the properties of these nuclei in the laboratory can therefore further our understanding of these astrophysical explosions. The TwinSol separator at the University of Notre Dame has recently been used to produce intense (∼10"6 pps) beams of "1"7F. In this article, some of the first measurements with these beams are discussed. (paper)