J. G. Ross

The influence of low-energy resonances on the reaction rate of 18O(α, γ)22Ne☆

Abstract The 18 O( 6 Li,d) 22 Ne α-transfer reaction has been used to study the level structure of 22 Ne around the α-threshold and to identify natural-parity states in that excitation range. The 18 O(α, γ) 22 Ne reaction has been studied in the energy range between 340 and 800 keV to determine the existence of possible resonances and to investigate their influence on the reaction rate of 18 O(α, γ) 22 Ne.

Explosive hydrogen burning of 31P

Abstract Proton threshold states in 36 Ar have been studied via the reactions 35 Cl( 3 He, d) 36 Ar, 32 S( 6 Li, d) 36 Ar, 32 S(α, γ) 36 Ar, 35 Cl(p, γ) 36 Ar and 35 Cl(p, α) 32 S to investigate their influence on a possible SC1 reaction cycle in explosive hydrogen burning. Three new states in 36 Ar have been observed in the ( 3 He, d) reaction at E x = 8806, 8887 and 8923 keV. Deuteron angular distributions were measured for 14 states near the 35 Cl+p threshold and were analyzed with DWBA calculations. Values of transferred orbital angular momenta, spectroscopic factors and proton partial widths were determined. Gamma-ray spectra have been measured at ten (p, γ) resonances. Three new resonances were observed at E R = 311, 416 and 627 keV, corresponding to 36 Ar states at E x = 8806, 8909 and 9117 keV, respectively. Excitation and resonance energies, γ-ray branching ratios and resonance strengths are presented. The astrophysical implications of our results for explosive hydrogen burning of 35 Cl are discussed.

Lifetimes of levels in [sup 20]F

The {sup 20}F levels at excitation energies between 2.5 and 3.5 eV are the mirror states of {sup 20}Na just above the proton threshold. Knowledge of the lifetime of the {sup 20}F levels allows the determination of the {gamma}-widths of the resonances in the {sup 19}Ne(p,{gamma}) reaction and calculatation of their resonance strengths. The states were populated using the {sup 19}F(d,p){sup 20}F reaction at E(d)= 2 MeV. The protons were detected in two Si-detectors and the {gamma}-rays were observed in a Ge detector in coincidence with the protons. Lifetime were deduced from the observed Doppler shifts and these results will be compared with results from a previous experiment.

The reaction rate for 31S(p,γ)32Cl and its influence on the SiP‐cycle in hot stellar hydrogen burning

The 31S(p, γ)32Cl reaction rate has been measured for 3He energies between 22.5 and 25 MeV at forward angles. Excitation energies and spin‐parities of the observed levels in 32Cl are derived. These data are used to calculate flow patterns of nuclear reactions in the mass range A=22–26 for temperatures and densities of astrophysical interest. (AIP)