Gießen 2007 – scientific programme
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HK: Fachverband Physik der Hadronen und Kerne
HK 21: Kern- und Teilchen-Astrophysik
HK 21.3: Talk
Tuesday, March 13, 2007, 17:30–17:45, E
Neutrino nucleosynthesis of the exotic nuclei 138La and 180Ta by charged current reactions* — •A. Byelikov for the LaTa collaboration — Institut für Kernphysik, TU Darmstadt
The nucleosynthesis of the exotic heavy odd-odd
nuclides 138La and 180Ta, amongst the rarest in nature,
is a long-standing problem. Both are shielded against the
r-process, and 138La is bypassed in the s-process, while
production of 180Ta may be possible through neutron capture
on the long-lived 179Ta [1]. The p-process has been suggested
as a source of 180Ta, but 138La is significantly
underproduced in all reasonable scenarios. Another possible source
are charged-current neutrino-nucleus reactions [2] of the type
(νe,e−) which would be dominated by the GT− response. The
main GT− resonance lies above the particle threshold and,
therefore, does not contribute. At present, the modelling is based
on (1p-1h) RPA calculations only, whose capability to describe the
response below the main GT resonance is questionable. However, the
corresponding GT− strength distributions can be measured with
high resolution even in heavy nuclei utilizing the (3He,t)
reaction at intermediate energies under 0∘. Measurements of
the 138Ba(3He,t)138La and
180Hf(3He,t)138Ta reactions have been performed at
RCNP, Osaka. The final B(GT) strength distributions and their
astrophysical implications are presented.
F. Käppeler et al., Phys. Rev. C 69, 055802 (2004).
A. Heger et al., Phys. Lett. B 606 258 (2005).
*Supported by the DFG through SFB 634 and 446 JAP-113/267/0-1.