a study of the 30 p(p, ) 31 s reaction via the 32 s(d,t) 31 s reaction and its astrophysical...

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