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[en] The structure of proton-unbound states in 30S and 31S is important for determining the 29P(p,γ)30S and 30P(p,γ)31S reaction rates, which influence explosive hydrogen burning in classical novae. The former reaction rate in this temperature regime had been previously predicted to be dominated by two low-lying, unobserved, Jπ = 3+ and 2+ resonances in 30S. To search for evidence for these levels, the structure of 30S was studied using the 32S(p,t)30S reaction with a magnetic spectrograph. We provide an update on the status of the ongoing analysis and some preliminary results.
Journal
No abstract available
Source
Boer, J. de; Mang, H.J. (eds.); v. 1 p. 719; ISBN 0720402808; 
; 1973; North-Holland Publishing Company; Amsterdam; International conference on nuclear physics; Munich, Germany; 27 Aug 1973; Short communication only.
; 1973; North-Holland Publishing Company; Amsterdam; International conference on nuclear physics; Munich, Germany; 27 Aug 1973; Short communication only.
[en] Isotopic abundance ratios of 30Si/28Si found in presolar SiC grains of suspected nova origin agree qualitatively with proposed oxygen-neon (ONe) nova composition but fail to agree quantitatively with ejecta predictions made by hydrodynamic ONe nova models. The Astrophysical 30P(p,γ)31S reaction rate is a key quantity used in nova models that predict isotopic abundances produced during nucleosynthesis leading up to the outburst. Currently, there is a large uncertainty in the rate at nova temperatures (0.1 < T < 0.4 GK) causing the predicted 30Si abundance ratio to vary by a factor of 4. The 30P(p,γ)31S reaction rate can be determined indirectly by measuring triton momenta from 32S(d,t)31S reactions. 31S Resonant states measured up to 600 keV above the proton threshold of 6131 keV and within the Gamow window which contribute most significantly to the rate can then be used to re-evaluate the rate for nova temperatures and reduce the uncertainty.
Journal
Journal of Physics. Conference Series (Online); ISSN 1742-6596; ; v. 381(1); [4 p.]
; v. 381(1); [4 p.]
[en] C, N, O, F and P can be analyzed by instrumental photon activation analysis (IPAA) including decay curve analysis. The interference of 30P (T1/2 = 149.9 s) by 15O (T1/2 = 122.2 s) can be ruled out by direct positron measurement making use of the largely different maximum β+-energies of both nuclides (3.24 MeV and 1.73 MeV, respectively). Interference by carbon (11C) can be avoided by sub-threshold activation with 17 MeV bremsstrahlung. The short half-life of 30P allows a high productivity of the method. Reliability was demonstrated in the range of 0.2%-2% P (detection limit = 40 μg/g). Analysis of a certified reference material (BCR-CRM 063) yielded excellent agreement with the certified data. (author)
Journal
Journal of Radioanalytical and Nuclear Chemistry; ISSN 0236-5731; ; CODEN JRNCDM; v. 276(1); p. 251-255
; CODEN JRNCDM; v. 276(1); p. 251-255
[en] Whether isospin is conserved for states in a highly excited compound nucleus or not, gives information on the Coulomb interaction which affects the decay properties of the compound nucleus. The isospin-dependent level decay widths of 30P are calculated by means of Weidenmuller's statistical theory. It takes the isospin coupling coefficients into account for transmission coefficients as well as for the total number of decay channels. This constitutes the difference from that of the Hauser-Feshbach formula
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