New22Ne(?,n)25Mg-resonances at very low energies relevant for the astrophysical s-process

Abstract

Abstract:The ~2Ne (a, n)

Photoexcitation of astrophysically important states inMg26. II. Ground-state-transition partial widths

“…[27] the one state observed above the neutron-separation energy at 111 54 keV is J = 1 + . This state has long been suspected of being natural parity [20] and several experiments have attempted to observe this state by 22 Ne(α,n) 25 Mg [11,12,14,16] with only upper limits reported. The two states at E x = 10805.7 (7) −B ] fit was found to reproduce the distribution well over the entire branching ratio parameter space.…”

“…Several experiments have been performed making direct measurements of the 22 Ne(α,n) 25 Mg [9][10][11][12][13][14] and 22 Ne(α,γ ) 26 Mg [13,15] reactions. These measurements have been unable to access the astrophysical energy region because of the relatively high α penetrability through the Coulomb barrier as well as unwanted background from cosmic rays and beam induced reactions.…”

Probing astrophysically important states in theMg26nucleus to study neutron sources for thesprocess

“…Considerable efforts have been made in the past to perform direct measurements of the 22 Ne(α,n) 25 Mg ( [43], [44], [45], [46], [47] and [48]) and the 22 Ne(α, γ) 26 Mg ( [47] and [49]) reactions. Unfortunately, in the astrophysical region of interest, α-penetrability is largely suppressed by the Coulomb barrier and very difficult to measure because of the cosmic and beam-induced background in the detector materials.…”

Resonance neutron-capture cross sections of stable magnesium isotopes and their astrophysical implications

“…Despite several attempts to measure the reaction cross section [52][53][54][55], these experiments failed to reach the low α energies of astrophysical relevance, mostly because cosmic-ray induced background starts to dominate the experimental signatures below E α = 0.5 MeV. A series of indirect measurements via α-particle transfer reactions have been performed to overcome this limitation [56,57].…”