12C and the triple-α reaction rate

Oliver Sølund Kirsebom

doi:10.1088/1742-6596/436/1/012072

Abstract

We briefly review the role of the triple-α reaction in astrophysics and discuss the uncertainties associated with the determination of the reaction rate. We summarize the results of three recent experimental studies of the breakup of the Hoyle state in 12C into three a particles, and we show how these results eliminate an often overlooked source of uncertainty in the determination of the triple-α reaction rate. Finally, we contemplate whether improved studies of the breakup of the Hoyle state can teach us something about the structure of the Hoyle state.

Highlights

The cross section of a nuclear reaction A + B → X + Y + . . . can be enhanced by many orders of magnitude if the compound nucleus, C = AB, has a state with the appropriate quantum numbers at an energy corresponding to the combined energy of the reactants, A and B; we speak of resonance in the channel A + B
The famous Hoyle state in 12C provides arguably the best example of this connection. Were it not for the tendency of nucleons to cluster into α particles, the Hoyle state would not exist, and without the Hoyle state little carbon would be produced in stars [1]. (And without carbon, we humans would not exist.)
Astrophysical importance The triple-α reaction, i.e. the fusion of three α particles into a 12C nucleus, plays a role in many astrophysical processes, but its great importance in astrophysics is to be attributed to two circumstances in particular: Firstly, it is the main mechanism behind stellar synthesis of carbon, essential to life as we know it on earth, and secondly, it is the mechanism by which the first generation of stars, created from the hydrogen and helium ashes of the Big Bang, were able to bridge the A = 5 and A = 8 mass gaps, allowing nucleosynthesis to proceed

Summary

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This article has been downloaded from IOPscience. Please scroll down to see the full text article. 2013 J. 10th International Conference on Clustering Aspects of Nuclear Structure and Dynamics

Introduction

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Findings

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