Calculation Of The 12C+a Capture Cross Section at Stellar Energies

Abstract

The 12C(0:, y) 160 cross section is calculated at stellar energies, using R-matrix parameters obtained by fitting consistently the 12C+", scattering phase shifts and the ",-spectrum from 16N f:l-decay. This limits the 12C+", channel radius to the range 5-7 fm. The S-factor at Eo< = 400 keV is calculated to lie in the range 0·05-0,33 MeV.b.

Further measurement of the beta-delayed alpha-particle emission of 16N

“…Barker [4,5] proposed the use of the β-delayed α-particle emission spectrum of 16 N to constrain S E1 , the p-wave component of the astrophysical cross section factor. At the time of these calculations [4,5], a single β-delayed α-particle emission spectrum with very high statistics ( > 36 million counts) existed. These data were measured at Mainz [8,9,10] in a successful measurement of the parity violating 1.281 MeV α-particle decay.…”

“…α-particles emitted from the continuum of 16 O populated by the β-decay of 16 N) has been predicted to provide a constraint on the cross section of this reaction [4,5,6,7], but it requires a measurement of a β-decay of 16 N with a sensitivity for a Branching Ratio (BR) of the order of 10 −9 . In particular, the low energy portion of the alpha-particle spectrum has been predicted to be sensitive to the reduced α-particle width of the bound 1 − state in 16 O; however, it cannot directly determine the mixing phase in the 12 C(α, γ) 16 O reaction of the two interfering states at 7.12 MeV and 9.58 MeV in 16 O.…”

β-delayed α decay of 16N and the 12C(α,γ)16O cross section at astrophysical energies: A new experimental approach

“…In 1971, Barker [7] proposed an experimental method to investigate the C+α. Information about the E 1 component of the astrophysical factor can be extracted from the height of the peak located at roughly E c.m.…”

“…Di Pietro 2) , P. Figuera 2) , M. Gulino 2,3) , M. La Cognata 2) , M. Lattuada 1,2) , C. Spitaleri 1,2) , H. Yamaguchi , S. Kubono 5) , Y. Wakabayashi 5) , T. Hashimoto 6) , N. Iwasa 7) , Y. Okoda 7) , K. Ushio 7) , T. Teranishi 8) , M. Mazzocco 9) , C. Signorini 9) , D. Torresi O. Carbon and oxygen abundance depends on the relative cross section of the reaction and on stellar temperature and density.…”

Nuclear astrophysics with secondary (Radioactive) beams

“…We emphasize that these predictions were published approximately five years prior to the observation of the anomaly interference structure around 1.1 MeV [13,9]. The previously measured beta-delayed alpha-particle emission of 16 N [19] was analyzed using R-matrix theory by Barker [20] and lately by Ji, Filippone, Humblet and Koonin [21]. They conclude that the data measured at higher energies is dominated by the quasi bound 1 − state in 16 O at 9.63 MeV and shows little sensitivity to the interference with the bound 1 − state.…”