a study of the 30 p(p, ) 31 s reaction via the 32 s(d,t) 31 s reaction and its astrophysical...
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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
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(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
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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
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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)
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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
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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
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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
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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
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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
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Maier-Leibnitz-Laboratorium (MLL)
13 MV tandem
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The Q3D Spectrometer
Ω ~ 14 msr (acceptance) ΔE/E ~ 2 x 10-4 (resolution)
Δρ ~ 6 cm (dispersion)
Maier-Leibnitz-Laboratorium (MLL) in Munich
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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
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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
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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
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Alan A. ChenKiana Setoodehnia
Jun Chen
Ralf Hertenberger Hans-Friedrich Wirth
Reiner KrückenThomas Faestermann
Shawn BishopAnuj Parikh
Clemens HerlitziusVinzenz BildsteinKatrin Eppinger
Olga LepyoshkinaPeter Maierbeck