Messung und Analyse von Winkelverteilung und Wirkungsquerschnitt der Reaktion F19(p,?0)O16 im Energiebereich 0,4 bis 0,72 MeV

Abstract

Total and differential cross section from F TM (p, %) 016 has been studied at effective proton energies 0,485; 0,55; 0,60; 0,64; 0,676; 0,72MeV. In this range of energy the angular distribution shows a pronounced energy dependence. An analysis of the results has made it possible to determine the state of the known resonance at 0,72 MeV. Moreover, the existence of some weak broad resonances below 0,7MeV could be gathered from the angular distribution. This is in agreement with earlier considerations made by GERJUOY.

A proposed direct measurement of cross section at Gamow window for key reaction 19F(p,α) 16O in Asymptotic Giant Branch stars with a planned accelerator in CJPL

“…This conclusion disagrees with the older measurement [20], where the existence of two resonances with J π =1 − and 0 + had been reported at E cm ∼0.4 MeV. Actually, additional resonances might be populated in 20 Ne [32]. A recent experiment [33] measured the 19 F(p,α 0 ) 16 O astrophysical S (E)-factor by indirect means of the Trojan Horse method, and found that the largest rate difference, about 70%, occurs at temperatures relevant for post-AGB stars (∼0.1 GK), exceeding the upper limit set by the previous uncertainties [28].…”

“…The Gamow window is only partially covered by the unpublished data of Lorentz-Wirzba [29], which were utilized [30,31] later to evaluate the astrophysical factor in the zero and finite-range Distorted Wave Born Approximation (DWBA) approaches. These data support a strong suppression of compound 20 Ne decay to the ground state of 16 O at E cm ∼0.14-0.6 MeV. However, these results were not included in the NACRE compilation as possible systematic errors affecting the absolute normalization might lead * Refer to five proposals submitted to NSFC in 2014, W.P.…”

“…=461 keV [20]. The Gamow window is only partially covered by the unpublished data of Lorentz-Wirzba [29], which were utilized [30,31] later to evaluate the astrophysical factor in the zero and finite-range Distorted Wave Born Approximation (DWBA) approaches.…”

Investigation of the19F(p, α)16O reaction in the THM framework

“…The astrophysical factor was then extrapolated to low energies assuming a dominant contribution of the non-resonant part [16]. This conclusion disagrees with older measurements in [15], where the existence of two resonances with J π = 1 − and 0 + had been reported at E cm ∼ 0.4 MeV. It is worth noting that additional resonances might be populated in 20 Ne as they are permitted by their quantum numbers [25].…”

“…In the NACRE compilation [16], containing the most recent cross-section measurements, the recommended 19 F(p, α 0 ) 16 O astrophysical S(E)-factor, which is the dominant channel at astrophysical energies, was obtained from several works [15,22,14,23,13,24], with the lowest-energy direct data reaching 461 keV center-of-mass energy [15]. The Gamow window is only partially covered by the unpublished data of [18], which have been used in [19,20] to evaluate the astrophysical factor in the zeroand finite-range DWBA approaches, respectively.…”