Measurement of the decay branching ratios of the {alpha}-unbound states in {sup 19}Ne and the {sup 15}O({alpha},{gamma}) reaction rate

Journal Article · Fri May 15 04:00:00 EDT 2009 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PHYSREVC.79.055805· OSTI ID:21286984

Tan, W P; Goerres, J; Beard, M; Couder, M; Couture, A; Falahat, S; Fisker, J L; Lamm, L; LeBlanc, P J; Lee, H Y; O'Brien, S; Palumbo, A; Stech, E; Strandberg, E; Wiescher, M ^[1]

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1. Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556 (United States)

The breakout reaction {sup 15}O({alpha},{gamma}){sup 19}Ne from the hot CNO cycle is critical to understanding explosive astrophysical phenomena such as x-ray bursts. In spite of considerable past experimental effort via indirect methods, this reaction rate remained mostly uncertain until our recent measurement [Phys. Rev. Lett. 98, 242503 (2007)] of the eluding {alpha}-decay branching ratios of the near-threshold states in {sup 19}Ne, particularly the critical level at 4.03 MeV. In this paper, we present more details of and deeper insights into the measurement and the uncertainties of the experimental results. The {alpha}-unbound states in {sup 19}Ne were populated via the reaction {sup 19}F({sup 3}He,t), and the {alpha}-decay branch was observed from t-{alpha} coincidences using a low-energy particle detection array and the TWINSOL facility at the University of Notre Dame. In particular, the measured branching ratio of the 4.03-MeV state is 2.9{+-}2.1x10{sup -4}. In combination with previous measurements of the lifetimes of these states, a new experimental reaction rate of {sup 15}O({alpha},{gamma}){sup 19}Ne is proposed and discussed in the astrophysical scenario. Further experimental investigations are necessary to reduce the remaining uncertainties.

• OSTI ID: 21286984
• Journal Information: Physical Review. C, Nuclear Physics, Journal Name: Physical Review. C, Nuclear Physics Journal Issue: 5 Vol. 79; ISSN 0556-2813; ISSN PRVCAN
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ALPHA DECAY
ASTROPHYSICS
BRANCHING RATIO
CNO CYCLE
FLUORINE 19
GAMMA DECAY
HELIUM 3
LIFETIME
MEV RANGE 01-10
NEON 19
NUCLEAR REACTIONS
OXYGEN 15
REACTION KINETICS
X RADIATION