2020/10/12 by J. Bishop, G. V. Rogachev, S. Ahn +19
Physics and Astronomy · #Algorithm #Alpha decay #Alpha particle #Atomic physics #Beta decay #Branching fraction #Component (thermodynamics) #Gamma spectroscopy #High-Energy Particle Collisions Research #Nuclear physics #Nuclear physics research studies #Physics #Quantum Chromodynamics and Particle Interactions #Quantum mechanics #Sensitivity (control systems) #Spectroscopy #State (computer science) #nucl-ex
paper · pdf · doi:10.1103/physrevc.102.041303
published as Phys. Rev. C 102, 041303(R) (2020)
openalex publication_date 2020/10/12 · arxiv created 2020/12/15 · arxiv updated 2020/12/16 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Background: The structure of the Hoyle state, a highly \ensuremathα-clustered state at 7.65 MeV in 12C, has long been the subject of debate. Understanding if the system comprises of three weakly interacting \ensuremathα particles in the 0s orbital, known as an \ensuremathα-condensate state, is possible by studying the decay branches of the Hoyle state.Purpose: The direct decay of the Hoyle state into three \ensuremathα particles, rather than through the 8Be ground state, can be identified by studying the energy partition of the three \ensuremathα particles arising from the decay. This paper provides details on the breakup mechanism of the Hoyle stating using a new experimental technique.Method: By using \ensuremathβ-delayed charged-particle spectroscopy of 12N using the Texas active target time-projection chamber, a high-sensitivity measurement of the direct 3\ensuremathα decay ratio can be performed without contributions from pileup events.Results: A Bayesian approach to understanding the contribution of the direct components via a likelihood function shows that the direct component is <0.043% at the 95% confidence level. This value is in agreement with several other studies, and, here, we can demonstrate that a small nonsequential component with a decay fraction of about 10^\ensuremath-4 is most likely.Conclusion: The measurement of the nonsequential component of the Hoyle state decay is performed in an almost medium-free reaction for the first time. The derived upper limit is in agreement with previous studies and demonstrates sensitivity to the absolute branching ratio. Further experimental studies would need to be combined with robust microscopic theoretical understanding of the decay dynamics to provide additional insight into the idea of the Hoyle state as an \ensuremathα condensate.