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

(p  ) Reaction on Phosphorus Isotope 30 P 30 P(p  ) 31 S 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

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 ~ ergs Temperature 0.1 – 0.4 GK – M sun of material ejected

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

SiC Presolar Grains 30 Si/ 28 Si & 29 Si/ 28 Si 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

29 S 30 S 31 S 32 S 28 P 29 P 30 P 31 P 27 Si 28 Si 29 Si 30 Si 187 ms ms s s s m (p  (p  (( 1 st path: Increases the 30 Si abundance through 30 P(β + ) 30 Si (beta decay) 30 P(p,  ) 31 S in Novae 2 nd path: Bypasses the production of 30 Si The 30 P(p,  ) 31 S reaction determines what happens in nova nucleosynthesis beyond A  30

Represents a quantitative measure for the nuclear reaction probabilities. Reaction: 30 P(p  31 S (Q-value = ± 1.5 keV) Resonant rate = 1.54*10 11 (μT 9 ) -3/2 Σ i (ω  ) i exp( *E i /T 9 ) ω  = strength = a*b, where: a = (2J f +1) / [(2J p +1)(2J t +1)] b = Γ p Γ  / Γ total for (p,  ) reaction Reaction Rate

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

ReactionImportancebeam availableIndirect approach 30 P(p,  ) 31 S nucleosynthesis in novae beyond A ~ 30 NO 32 S(d,t) 31 S (Irvine et al.) 30 P(p,  ) 31 S via 32 S(d,t) 31 S 30 P is unstable; currently no radioactive beam available different transfer reactions are complementary

Maier-Leibnitz-Laboratorium (MLL) 13 MV tandem

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

32 S(d,t) 31 S Experiment by the Q3D Spectrometer Maier-Leibnitz-Laboratorium (MLL) in Munich, Germany  Ω ~ 14 msr (acceptance) ΔE/E ~ 2 x (resolution) Δρ ~ 6 cm (dispersion) The Q3D spectrometer 24 MeV 0.5 – 1 e  A 2 H beam 3H3H Target: 10.5  g/cm 2 32 S implanted into 55.9  g/cm % enriched 12 C Detected in the multi- wire proportional counter (MWPC) and the scintillator Dipole 1 Dipole 2 Dipole 3

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

Future Work Perform the final 32 S(d,t) 31 S 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 31 S states Re-evaluate the 30 P(p,  ) 31 S reaction rate

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