1 TU Darmstadt, Germany — 2 Osaka University, Japan — 3 iThemba LABS, South Africa —
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Transcript of 1 TU Darmstadt, Germany — 2 Osaka University, Japan — 3 iThemba LABS, South Africa —
A. Byelikov1, T. Adachi2, H. Fujita3, Y. Fujita2, A. Heger4, Y. Kalmykov1, K. Langanke5,
G. Martínez-Pinedo5, PvNC1, R. Neveling3, A. Richter1, A. Shevchenko1,
Y. Shimbara2, F.D. Smit3, A. Tamii6, S.E. Woosley7 and M. Yosoi6
1TU Darmstadt, Germany — 2Osaka University, Japan — 3iThemba LABS, South Africa —
4LANL, USA, 5GSI Darmstadt, Germany — 6RCNP Osaka, Japan — 7UC Santa Cruz, USA
Neutrino Nucleosynthesis of Exotic, Odd-Odd Nuclei 138La and 180Ta
Peter von Neumann-Cosel Institut für Kernphysik, Technische Universität Darmstadt
S-DALINAC
TU DARMSTADT
Motivation
Neutrino nuclesynthesis of 138La and 180Ta
High resolution measurement of GT strength
Astrophysical implications
Outline
180Ta
138La
Exotic Nuclides
Nucleosynthesis of 138La
s-process r-process p-process
Production through Neutrino Processes
Neutral current reactions: 139La(,′n)138La 181Ta(,′n)180Ta
Charged current reactions: 138Ba(e,e)138La 180Hf(e,e)180Ta
Complete stellar evolution in massive stars with improved RPA calculations for -nucleus reactions
A. Heger et al., Phys. Lett. B 606 (2005) 258
138La: pure process production by cc reactions
Different Production Processes of 138La
180Ta: 50% process, 50% p process
Theoretical Prediction
Low neutrino energies small q L = 0 GT strength
RPA predicts main GT resonance well above neutron threshold Predictions for the low-lying strength are questionable
Experimental Requirements
(e,e) Gamow-Teller strength (p,n) or (3He,t)
Gamow-Teller part narrow angle cut around 0°
Intermediate energies (100 – 400 MeV/u)simple one-step reaction mechanism
spin – isospin response enhanced
(3He,t) reaction at RCNP
138La Spectrum
Target: 138BaCO4 embedded in polyvinylalcohol
RCNP
GT Strength Distribution in 138La
Cumulative Strength in 138La
B(GT–)exp 117% B(GT–)theo at 7.47 MeV
Cumulative Strength in 180Ta
B(GT–)exp 276% B(GT–)theo at 6.64 MeV
1
138La yield
Yields of 138La and 180Ta for a 15 M Star
solar
2
3
4
2
180Ta yield
solar
4
6
8
-process
ch. curr. 8 MeV
neut. curr.
ch. curr. 4 MeV
Branching ratio to 180Ta isomer about 35%
Conclusions
GT strength in 138La and 180Ta below particle threshold extracted
138La is essentially produced in the process
180Ta at least partially produced in the process
Full results: A. Byelikov et al., PRL 98, 082501 (2007)