Development of the program LISE: application to fusion–evaporation

Resonances in19Ne with relevance to the astrophysically important18F(p,Mountford1, Murphy2, Achouri3 et al. 2012Phys. Rev. C

“…The center of mass excitation functions for the 18 15 O channel because of the contamination due to 4 He ions present in the beam. Furthermore, despite the good intrinsic energy resolution determined from the Monte Carlo simulations, the limited statistics have required that the spectra are binned at 25 keV (CM).…”

“…Key reasons for the high flux are that this isotope is produced relatively abundantly, and its lifetime of ∼158 minutes is well matched to the timescale for nova ejecta to become transparent to gamma-ray emission. There remains however a large uncertainty on the absolute flux, and by implication the detectability distance for novae, because of uncertainty in the rates of the nuclear reactions producing and destroying 18 F. Of these, the reaction which contributes the most uncertainty to the final abundance of 18 F is that of 18 F(p,α) 15 O. It is this reaction which is the focus of the present work.…”

“…The target then consisted of 55 ± 4 µm of low density PTFE (CH 2 polymer), thick enough to stop the beam, but thin enough to allow light ions to escape. Protons and alpha particles, emitted from 18 F(p,p) 18 F and 18 F(p,α) 15 O reactions in the target, were detected in a 50 mm × 50 mm double sided silicon strip detector (Micron Semiconductors Ltd. type-W [9]) located 248 ± 1 mm downstream of the target. Carbon ions were also observed from 18 F( 12 C, 12 C) 18 F scattering.…”

“…Energy losses in the degrader, the target and in detector dead layers were based on SRIM2008.04 [12]. The algorithm was then applied to each event to generate center of mass energy spectra for the 18 F(p,p) 18 F and 18 F(p,α) 15 O reactions. The resulting spectra are presented in Figure 3.…”

“…In the energy region of interest, several states in 19 Ne may make resonant contributions to the 18 F(p,α) 15 O reaction rate (see [2] for a recent summary). S-and p-wave resonances just above and below the 18 F+p threshold at 6411 keV have proven difficult to measure, although some recent progress has been made [3].…”