ConstrainingAl26+presonances usingAl

Abstract

Si stellar reaction rate are discussed.

Angle-integrated measurements of the 26Al (d, n)27Si reaction cross section: a probe of spectroscopic factors and astrophysical resonance strengths

“…Considering the 11/2 − state at 7652 keV, corresponding to the resonance at 189 keV, the present data agree within errors, but give a relatively higher value, compared with the C 2 S(l = 1) value obtained for the state in the ( 3 He, d) study [14], and the study of the mirror analog state in the (d, p) reaction [15], assuming pure l = 1 transfer (see table 1). The weighted mean value of the resonance strength obtained from the two direct measurements of 45 +19 −17 μeV [6,7] implies C 2 S(l = 1) ≈ 0.1 (it is the l = 1 contribution that determines ωγ).…”

“…The upper limit on the (d, n) cross section to the 7590 keV state gives a C 2 S(l = 0) limit consistent with the limit obtained in the ( 3 He, d) study [14] 2 S(l = 3) components (0.02 and 0.07, respectively) that are more compatible with experiment. This would then imply that there is mixing between these theoretical states.…”

“…Using the present data this would require a dominant l = 2 component in the (d, n) transfer cross-section data with a value C 2 S(l = 2) ≈ 0.1. This would be consistent with the value obtained by Vogelaar et al in the ( 3 He, d) study assuming pure l = 2 transfer [14]. However, this is inconsistent with the shellmodel calculation which predicts approximately equal values for C 2 S(l = 0) ≈ 0.01 and C 2 S(l = 2) ≈ 0.01.…”

“…The 127 keV resonance is, however, at too low an energy, and has therefore too low a cross section for a direct measurement to be presently feasible. A ( 3 He, d) transfer reaction study on a 26 Al target set a (ldependent) limit on the spectroscopic factor C 2 S for the 127 keV resonance [14], and inferred an upper limit on its strength (since Γ γ Γ p , it is Γ p that determines the resonance strength, ωγ). In the work of Lotay et al [10] [9,10] were then used to estimate resonance strengths for the analog states in 27 Si.…”

Synthesis of the elements in stars: forty years of progress

“…However, the rate for T 9 р0.15 is quite uncertain, again because of the possibility of several unobserved lowenergy resonances. None of these states were detected in ( 3 He,d) measurements (Vogelaar, 1989, Vogelaar et al, 1996, but they have been treated theoretically by Champagne et al (1993). Although the results of these calculations seem justified, there is little in the way of experimental information (in particular, spins, parities, or spectroscopic factors) that would support them.…”