A measurement of Γrad/Γ for the 7.654 MeV state of 12C and the rate of the stellar 3α reaction

Markham, R.G.; Austin, Sam M.; Shahabuddin, M.A.M.

doi:10.1016/0375-9474(76)90458-9

Cited by 38 publications

(18 citation statements)

References 12 publications

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“…The radiative branching ratio has been determined to be À rad =À ¼ 4:12ð11Þ Â 10 À4 [6], so, to a good approximation, À ' À . The largest source of uncertainty in the evaluation of the reaction rate is the radiative width, À rad , which is determined from the combined measurement of the radiative branching ratio, À rad =À; the e þ e À pair-decay branching ratio, À =À; and the e þ e À pair-decay width, À .…”

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confidence: 99%

Improved Limit on DirectαDecay of the Hoyle State

et al. 2012

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The current evaluation of the triple-reaction rate assumes that the decay of the 7.65 MeV, 0 þ state in 12 C, commonly known as the Hoyle state, proceeds sequentially via the ground state of 8 Be. This assumption is challenged by the recent identification of two direct -decay branches with a combined branching ratio of 17ð5Þ%. If correct, this would imply a corresponding reduction in the triple-reaction rate with important astrophysical consequences. We have used the 11 Bð 3 He; dÞ reaction to populate the Hoyle state and measured the decay to three particles in complete kinematics. We find no evidence for direct -decay branches, and hence our data do not support a revision of the triple-reaction rate. We obtain an upper limit of 5 Â 10 À3 on the direct decay of the Hoyle state at 95% C.L., which is 1 order of magnitude better than a previous upper limit.

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confidence: 99%

Improved Limit on DirectαDecay of the Hoyle State

et al. 2012

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“…duced a promising result. Using the two break-up reactions 12 C( 4 He, 4 He + 4 He + 4 He) 4 He and 9 Be( 4 He, 4 He + 4 He + 4 He) n at 4 He beam energies between 22 and 30 MeV, excited states in 12 C that decay via the 8 Be ground-state were reconstructed. In both cases a state at 13.3 MeV was observed with angular distributions indicative of a I π = 4 + resonance.…”

Section: Hoyle-state Excitations: Recent Experimental Resultsmentioning

confidence: 99%

“…Figure 6. Spectrum from the 9 Be( 4 He, 4 He + 4 He + 4 He)n reaction at 26 MeV (dots). The fit to the data is given by the blue line and includes a 'new' peak at 13.3 MeV as well as the known natural parity states in 12 C selected by their decay through the 8 Be ground state.…”

Section: Hoyle-state Excitations: Recent Experimental Resultsmentioning

confidence: 99%

“…Examples include the symmetric 12 C-12 C cluster resonance in 24 Mg [8] and the well developed 16 O- 4 He structure of 20 Ne [9]. Alpha particles are by far the most ubiquitous sub-units within cluster states, arising from their strongly bound nature; the particle threshold at 19.81 MeV makes the α particle the most robust composite nucleus in the entire Segrè chart.…”

Section: Clustering and The Hoyle Statementioning

confidence: 99%

“…For example, it is not sufficient to produce 12 C in an excited state, but a significant route to the ground state is required. In the case of the Hoyle state, a 0.04% radiative branching ratio to bound states has been determined [4]. The dominant decay process undergone by the Hoyle state, as outlined above, is via the ground-state of 8 Be, with a limit on the direct disintegration into three α particles having recently been reported as <5×10 −3 [5].…”

Section: Introductionmentioning

confidence: 99%

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Who plays in the Hoyle band?

Kokalova

2014

EPJ Web of Conferences

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Abstract. The Hoyle state in 12 C was discovered over 50 years ago in 1957 and strongly influences the rate of the triple-alpha process in stars. Recently, significant experimental and theoretical effort has been invested to understand, in detail, its unorthodox structure. In particular, identification of excitations of the Hoyle state has been a key goal. This paper addresses the current progress with an emphasis on possible members of the Hoyle band and the structure implications.

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Bibliography

Jaklovsky¹

1981

Preparation of Nuclear Targets

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A measurement of Γrad/Γ for the 7.654 MeV state of 12C and the rate of the stellar 3α reaction

Cited by 38 publications

References 12 publications

Improved Limit on DirectαDecay of the Hoyle State

Improved Limit on DirectαDecay of the Hoyle State

Who plays in the Hoyle band?

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