AstrophysicalSfactor ofC12(α,γ)16

Abstract

The spectrum of low energy beta-delayed alpha-particle emission of ,6 N was measured with high sensitivity; e.g., at £a«l MeV, a sensitivity for a beta-decay branching ratio in the range of 10 ~9 (to 10 ~1 0 ) was achieved. We used previous theoretical work of Ji, Filippone, Humblet, and Koonin to extract from these data the astrophysical p-wave S factor for the 12 C(a,y) 16 0 capture reaction, and find SfiOOO) =95 ± 16(stat) ± 28(syst) keVb. This result is crucial, for example, for understanding the last stages of a massive star before a supernova. PACS numbers: 23.60.+e, 25.55.Ci, 27.20.+n, 95.30.Cq

Synthesis of the elements in stars: forty years of progress

“…The spectra measured by the TRIUMF (Buchmann et al, 1993;Azuma et al, 1994) and Yale/Connecticut (UConn) (Zhao et al, 1993) groups are generally in good qualitative agreement. However, questions have been raised on both sides about important experimental details, such as the shape of the low-energy peak in the Yale/UConn measurement, the shape of the high-energy peak in the TRIUMF data compared to an earlier measurement (Neubeck, Schober, and Wä ffler, 1974), and the effect of target-thickness corrections on comparisons of the two measurements.…”

“…b. ␤-delayed ␣ spectrum from the decay of 16 N At least three groups (Buchmann et al, 1993;Zhao et al, 1993;Zhao et al, 1995) have measured the delayed ␣ spectrum from the ␤ decay of 16 N down to energies low enough to see the secondary maximum attributed to the presence of the subthreshold 1 Ϫ state. Some of these new spectral measurements have been included in the fitting along with direct measurements of the E1 cross section, in order to better constrain the parameters (in particlular, the reduced ␣ width) of the subthreshold state.…”

AstrophysicalSfactor of theC12(α,γ)O16An1, Chen2, Ma3 et al. 2015Phys. Rev. C23080View full textAdd to dashboardCite

“…= 3 and 4 MeV, where the calculation underestimates total cross-section. The latest results of [27], and Zhao 1993: [28], together with the decomposition into p-(dashed line) and f-wave (dotted line) contributions. For comparison, the best fits of Tang 2010: [26], Azuma 1994: [27], and Schürmann 2012: [40] scaled by the corresponding coefficients are shown.…”

“…Included in this analysis are the three independent α spectra data of Refs. [25][26][27][28], and the normalization for probability spectrum is used in the practice to reduce the influence of systematical errors. Fig.…”

“…To investigate the specific role of the 16 O nucleus for the S factor, a wealth of experimental data have been accumulated over the past few decades, including the precise measurements of total cross-section of 12 C(α, γ) 16 O [7][8][9][10], γ-ray angular distributions of ground state transition [11][12][13][14][15][16][17][18][19][20][21][22], cascade transitions [8,12,23,24], β-delayed α spectra for 16 N [25][26][27][28], transfer reaction [29][30][31], elastic scattering 12 C(α, α) 12 C [32][33][34][35][36] and additional particle reaction 16±16 Kunz [15] 165±50 76±20 85±30 4±4 Brune [29] 159 101±17 42…”