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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 : - PowerPoint PPT Presentation
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A Study of the 30P(p,)31S Reaction via the 32S(d,t)31S Reaction and its
Astrophysical Relevance
Dan Irvine
McMaster University
CAWONAPS 2010 Dec. 9-10
(p) Reaction on Phosphorus Isotope 30P
30P(p)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
Classical Novae
Stellar explosions in close binary systems consisting of a White dwarf and a low mass Main sequence star
Powered by thermonuclearrunaway on the surface of WD
Explosion:• energy released ~ 1045 ergs• Temperature 0.1 – 0.4 GK• 10-5 – 10-4 Msun of material ejected
http://pntpm3.ulb.ac.be/Trento/talks/pdf/jjose.pdf
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 30Si/28Si ratio• Lower than solar 29Si/28Si ratio
Nittler, Earth and Planetary Science Letts. 209(2003) 259)
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
29S 30S 31S 32S
28P 29P 30P 31P
27Si 28Si 29Si 30Si
187 ms
270.3 ms
1.178 s
4.142 s
2.572 s2.498 m
(p
(p
(
1st path: Increases the 30Si abundancethrough 30P(β+)30Si (beta decay)
30P(p,) 31S in Novae
2nd path: Bypasses the production of30Si
The 30P(p,)31S reaction determines what happens in nova nucleosynthesis beyond A 30
Represents a quantitative measure for the nuclear
reaction probabilities.
Reaction: 30P(p31S (Q-value = 6133.0 ± 1.5 keV)
Resonant rate = 1.54*1011 (μT9)-3/2 Σi (ω)i exp(-11.605*Ei/T9)
ω = strength = a*b, where:
a = (2Jf +1) / [(2Jp +1)(2Jt +1)]
b = Γp Γ / Γtotal for (p,) reaction
Reaction Rate
30P(p,)31S Reaction Rate
30P+p states in 31S up to about Ex 7 MeV contribute strongly to the 30P(p,)31S rate
Some of the known states lack firm spin-parity assignments The existence of unobserved states cannot yet be precluded
The 30P(p)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
30P+p
Q = 6133
0.1
GK
<=
T <
= 0
.4 G
K
31S
Reaction Importance beam available Indirect approach
30P(p,)31Snucleosynthesis in novae beyond A ~ 30
NO32S(d,t)31S (Irvine et al.)
30P(p,)31S via 32S(d,t)31S
• 30P 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 10-4 (resolution)
Δρ ~ 6 cm (dispersion)
Maier-Leibnitz-Laboratorium (MLL) in Munich
32S(d,t)31S Experiment by the Q3D Spectrometer
Maier-Leibnitz-Laboratorium (MLL) in Munich, Germany
Ω ~ 14 msr (acceptance) ΔE/E ~ 2 x 10-4 (resolution)
Δρ ~ 6 cm (dispersion)The Q3D spectrometer
24 MeV 0.5 – 1 eA 2H beam
3H
Target: 10.5 g/cm2 32S implanted into 55.9 g/cm2 99.9% enriched 12C
Detected in the multi-wire proportional counter (MWPC) and the scintillator
Dipole 1
Dipole 2
Dipole 3
32S(d,t)31S with the Q3D
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
Q3D = 20(preliminary)
[Ex(31S) ~ 7 MeV] [Ex(31S) ~ 6 MeV]
Co
nta
min
ant
Co
nta
min
ant
6.63
68 M
eV
6.74
90 M
eV
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,)31S reaction rate
Alan A. ChenKiana Setoodehnia
Jun Chen
Ralf Hertenberger Hans-Friedrich Wirth
Reiner KrückenThomas Faestermann
Shawn BishopAnuj Parikh
Clemens HerlitziusVinzenz BildsteinKatrin Eppinger
Olga LepyoshkinaPeter Maierbeck