Pair decay width of the Hoyle state and carbon production in stars

TL;DR

This paper presents a precise measurement of the pair decay width of the Hoyle state in carbon-12, improving the accuracy of data crucial for stellar nucleosynthesis models in supernovae and giant stars.

Contribution

It introduces a new, highly accurate measurement of the Hoyle state's pair decay width using electron scattering and a model-independent analysis, reducing previous uncertainties significantly.

Findings

Measured Gamma_pi as (62.3 +- 2.0) micro-eV.

Reduced uncertainty in decay width by over three times.

Provides data essential for supernova and stellar nucleosynthesis modeling.

Abstract

Electron scattering off the first excited 0+ state in 12C (the Hoyle state) has been performed at low momentum transfers at the S-DALINAC. The new data together with a novel model-independent analysis of the world data set covering a wide momentum transfer range result in a highly improved transition charge density from which a pair decay width Gamma_pi = (62.3 +- 2.0) micro-eV of the Hoyle state was extracted reducing the uncertainty of the literature values by more than a factor of three. A precise knowledge of Gamma_pi is mandatory for quantitative studies of some key issues in the modeling of supernovae and of asymptotic giant branch stars, the most likely site of the slow-neutron nucleosynthesis process.