Absolute determination of the {sup 22}Na(p,{gamma}){sup 23}Mg reaction rate in novae

Journal Article · Tue Mar 15 00:00:00 EDT 2011 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PHYSREVC.83.034611· OSTI ID:21499505

Sallaska, A L; Wrede, C; Garcia, A; Storm, D W; Brown, T A. D.; Snover, K A ^[1]; Ruiz, C; Ottewell, D F; Buchmann, L; Vockenhuber, C; Hutcheon, D A; Caggiano, J A ^[2]; Jose, J ^[3]

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1. Department of Physics, University of Washington, Seattle, Washington 98195-1560 (United States)
2. TRIUMF, Vancouver, BC V6T 2A3 (Canada)
3. Departament Fisica i Enginyeria Nuclear (UPC) and Institut d'Estudis Espacials de Catalunya (IEEC), E-08034 Barcelona (Spain)

Gamma-ray telescopes in orbit around the earth are searching for evidence of the elusive radionuclide {sup 22}Na produced in novae. Previously published uncertainties in the dominant destructive reaction, {sup 22}Na(p,{gamma}){sup 23}Mg, indicated new measurements in the proton energy range of 150 to 300 keV were needed to constrain predictions. We have measured the resonance strengths, energies, and branches directly and absolutely by using protons from the University of Washington accelerator with a specially designed beam line, which included beam rastering and cold vacuum protection of the {sup 22}Na implanted targets. The targets, fabricated at TRIUMF-ISAC, displayed minimal degradation over a {approx}20 C bombardment as a result of protective layers. We avoided the need to know the absolute stopping power, and hence the target composition, by extracting resonance strengths from excitation functions integrated over proton energy. Our measurements revealed that resonance strengths for E{sub p}=213, 288, 454, and 610 keV are stronger by factors of 2.4-3.2 than previously reported. Upper limits have been placed on proposed resonances at 198, 209, and 232 keV. These substantially reduce the uncertainty in the reaction rate. We have re-evaluated the {sup 22}Na(p,{gamma}) reaction rate, and our measurements indicate the resonance at 213 keV makes the most significant contribution to {sup 22}Na destruction in novae. Hydrodynamic simulations including our rate indicate that the expected abundance of {sup 22}Na ejecta from a classical nova is reduced by factors between 1.5 and 2, depending on the mass of the white-dwarf star hosting the nova explosion.

• OSTI ID: 21499505
• Journal Information: Physical Review. C, Nuclear Physics, Journal Name: Physical Review. C, Nuclear Physics Journal Issue: 3 Vol. 83; ISSN 0556-2813; ISSN PRVCAN
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ACCELERATORS
ALKALINE EARTH ISOTOPES
BARYON REACTIONS
BARYONS
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
CHARGED-PARTICLE REACTIONS
CROSS SECTIONS
DECAY
DIFFERENTIAL CROSS SECTIONS
DWARF STARS
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
ENERGY RANGE
EVEN-ODD NUCLEI
EXCITATION FUNCTIONS
EXPLOSIONS
FERMIONS
FORECASTING
FUNCTIONS
GAMMA DECAY
GAMMA RADIATION
HADRON REACTIONS
HADRONS
IONIZING RADIATIONS
ISOTOPES
KEV RANGE
KEV RANGE 100-1000
KINETICS
LIGHT NUCLEI
MAGNESIUM 23
MAGNESIUM ISOTOPES
MASS
NUCLEAR DECAY
NUCLEAR REACTIONS
NUCLEI
NUCLEON REACTIONS
NUCLEONS
ORBITS
PROTON REACTIONS
PROTONS
RADIATIONS
RADIOISOTOPES
REACTION KINETICS
RESONANCE
SECONDS LIVING RADIOISOTOPES
SIMULATION
SODIUM 22 TARGET
STARS
STOPPING POWER
TARGETS
WHITE DWARF STARS