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Dan Irvine McMaster University

A Study of the 30 P(p, g ) 31 S Reaction via the 32 S(d,t) 31 S Reaction and its Astrophysical Relevance. Dan Irvine McMaster University. CAWONAPS 2010. Dec. 9-10. ( p , g ) Reaction on Phosphorus Isotope 30 P. 30 P( p , g ) 31 S plays an important role in stellar nucleosynthesis :

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Dan Irvine McMaster University

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  1. A Study of the 30P(p,g)31S Reaction via the 32S(d,t)31S Reaction and its Astrophysical Relevance Dan Irvine McMaster University CAWONAPS 2010 Dec. 9-10

  2. (p,g) Reaction on Phosphorus Isotope 30P 30P(p,g)31S plays an important role in stellar nucleosynthesis: At nova temperatures between 0.1 – 0.4 GK: • Influences the dominant nova nucleosynthetic path connected to the Si isotopic abundance ratios in presolar grains of nova origin • Influences the abundances of nova nucleosynthesis in the 30 ≤ A ≤ 40 region At X-ray burst temperatures between 0.4 – 1.5 GK: • Has a strong impact on the reaction flow and nucleosynthesis in the burst J. José et al., Ap. J. 612(2004)414 J. José et al., Ap. J. 560(2001)897 J . José et al, Ap. J. Supp. 189 (2010)204

  3. Classical Novae • Stellar explosions in close • binary systems consisting of a • White dwarf and a low mass • Main sequence star • Powered by thermonuclear • runaway on the surface of WD • Explosion: • energy released ~ 1045 ergs • Temperature0.1 – 0.4 GK • 10-5 – 10-4Msunof material ejected http://pntpm3.ulb.ac.be/Trento/talks/pdf/jjose.pdf

  4. Presolar Grains Dust grains condensed in stellar atmospheres: “frozen” samples of the stellar nucleosynthesis Possible sources: • Red Giants • AGB Stars • Supernovae • Classical Novae Nittler et al. Ap.J. 601(2005)L89 Nittler, Earth and Planetary Science Letts. 209(2003) 259) Properties: • Higher than solar 30Si/28Si ratio • Lower than solar 29Si/28Si ratio Amari et al. Ap.J. 551(2001)1065 José et al. Meteoritics & Planetary Sciences 42(2007)1135

  5. SiC Presolar Grains 30Si/28Si & 29Si/28Si abundance ratio in presolar grains of nova origin Dominant nova nucleosynthetic path Structure of WD and peak temperatures during the nova outburst J. José et al. Ap.J. 612(2004)414

  6. 30P(p,g) 31S in Novae 1st path: Increases the 30Si abundance through 30P(β+)30Si (beta decay) 29S 30S 31S 32S 2.572 s 187 ms 1.178 s 2nd path: Bypasses the production of 30Si The 30P(p, g)31S reaction determines what happens in nova nucleosynthesis beyond A  30 28P 29P 30P 31P 2.498 m 270.3 ms 4.142 s 27Si 28Si 29Si 30Si (p,g) (b+) (p,a)

  7. Reaction Rate Represents a quantitative measure for the nuclear reaction probabilities. Reaction: 30P(p,g)31S(Q-value = 6133.0 ± 1.5 keV) Resonant rate = 1.54*1011 (μT9)-3/2Σi (ω)i exp(-11.605*Ei/T9) ω = strength = a*b, where: a = (2Jf +1) / [(2Jp +1)(2Jt +1)] b = Γp Γ/ Γtotalfor (p,) reaction

  8. 30P(p,g)31S Reaction Rate 30P+p states in 31S up to about Ex  7 MeV contribute strongly to the 30P(p,g)31S rate Some of the known states lack firm spin-parity assignments The existence of unobserved states cannot yet be precluded The 30P(p,g)31S reaction rate is thus uncertain over the temperature range of astrophysical interest: 0.1 – 1.5 GK Need to study the 30P+p states in 31S 0.1 GK <= T <= 0.4 GK 30P+p Q = 6133 31S

  9. 30P(p,)31S via 32S(d,t)31S • 30P is unstable; currently no radioactive beam available • different transfer reactions are complementary

  10. Maier-Leibnitz-Laboratorium (MLL) 13 MV tandem

  11. The Q3D Spectrometer Ω ~ 14 msr (acceptance) ΔE/E ~ 2 x 10-4 (resolution) Δρ ~ 6 cm (dispersion) Maier-Leibnitz-Laboratorium (MLL) in Munich

  12. 32S(d,t)31SExperiment by the Q3D Spectrometer Dipole 3 Dipole 2 Detected in the multi-wire proportional counter (MWPC) and the scintillator Dipole 1 Target: 10.5 g/cm232S implanted into 55.9 g/cm2 99.9% enriched 12C 3H Ω ~ 14 msr (acceptance) ΔE/E ~ 2 x 10-4 (resolution) Δρ ~ 6 cm (dispersion) The Q3D spectrometer Maier-Leibnitz-Laboratorium (MLL) in Munich, Germany 24 MeV 0.5 – 1 eA 2H beam

  13. Q3D = 20 (preliminary) 32S(d,t)31S with the Q3D 6.7490 MeV 6.6368 MeV Contaminant Contaminant Beam: 1 A of 24 MeV deuterons Target: 32S implanted into isotopically pure 12C foil Energy resolution: 4 keV 4 days of beamtime (so far)  10, 15, 20 and 25 [Ex(31S) ~ 6 MeV] [Ex(31S) ~ 7 MeV]

  14. Future Work • Perform the final 32S(d,t) 31S experiment • at MLL (Munich) in February 2011 to: • Try a non-contaminated target to remove contaminant peaks • Obtain the cross sections at a few more angles • Obtain the spins and parities of the 31S states • Re-evaluate the 30P(p,g)31S reaction rate

  15. Alan A. Chen Kiana Setoodehnia Jun Chen Reiner Krücken Thomas Faestermann Shawn Bishop Anuj Parikh Clemens Herlitzius Vinzenz Bildstein Katrin Eppinger Olga Lepyoshkina Peter Maierbeck Ralf Hertenberger Hans-Friedrich Wirth

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