High-Resolution Study of Isobaric Analog Resonances inNa23

Abstract

Excitation functions for the elastic scattering of protons by 22 Ne have been measured at 90°, 105°, 120°, 135°, 150°, and 160° from 0.8 to 3.13 MeV, and for the reaction 22 Ne(^') 22 Ne* (first excited state), at 90°, 120°, and 150° from 2.0 to 3.13 MeV, with an average energy resolution of about 250 eV. Spins, parities, and partial and total widths have been extracted for the large majority of the 76 resonances observed. Two isobaric analog states, those of the sixth and seventh excited states of 23 Ne, have been identified. Both analogs are evidenced as fragmentations of the broad T > states into enhancement of the background T< states. A sum rule applied to the individual fine-structure widths implies spectroscopic factors in agreement with those extracted from (d,p) stripping measurements on 22 Ne.

Thermonuclear rate for theF19(α,p)Ugalde1, Azuma2, Couture3 et al. 2008Phys. Rev. C284331View full textAdd to dashboardCite

“…This second possibility does not produce fluorine. The alternative 18 O(p, α) 15 N(α, γ ) 19 F capture reaction is the main fluorine production link in this scenario. The abundance of 15 N depends sensitively on the hydrogen abundance in the intershell region.…”

“…Fluorine nucleosynthesis in AGB stars takes place in the hydrogen-helium intershell region where the 14 N ashes from the preceding CNO burning are converted to 18 F by α-particle captures (a similar reaction path is followed by Wolf-Rayet stars). The unstable 18 F isotope decays with a half-life of 109.8 min to 18 O.…”

“…The unstable 18 F isotope decays with a half-life of 109.8 min to 18 O. Both a proton or an α-particle can be captured by 18 O.…”

“…The unstable 18 F isotope decays with a half-life of 109.8 min to 18 O. Both a proton or an α-particle can be captured by 18 O. In the former case, 4 He and 15 N are being produced, whereas in the latter case 22 Ne is formed.…”

“…Additional protons may be mixed into the region when the convective envelope penetrates the intershell region at the end of the third dredge-up (TDU). 14 C produced by this reaction provides a second link for the production of 18 O via 14 C(α, γ ) 18 O.…”