Dresden 2013 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 64: Struktur und Dynamik von Kernen
HK 64.4: Vortrag
Donnerstag, 7. März 2013, 15:00–15:15, HSZ-301
Nuclear Excitation by a Strong Zeptosecond Laser Pulse: Theoretical Expectations — Adriana Pálffy and •Hans A. Weidenmüller — Max-Planck-Institut für Kernphysik, Heidelberg
At the Nuclear Physics Pillar of the Extreme Light Infrastructure, efforts are under way to generate a multi-MeV zeptosecond laser beam [1]. Which reactions may occur when such a laser pulse hits a medium–weight or heavy target nucleus? The laser pulse consists of N ≲ 104 coherent photons and the nuclear response is characterized by the excitation rate N Γdip with the dipole width Γdip ≈ 5 keV, and by the spreading width Γ↓≈ 5 MeV. While the perturbative regime was addressed in Ref. [2], here we focus on the quasi-adiabatic regime N Γdip ≈ Γ↓ where the compound nucleus is excited to several 100 MeV above yrast.
We have developed a new approach [3] to nuclear level densities at high excitation energy and extended it beyond the constant-spacing model for the single-particle energies. This allows us to give a semi-quantitative description of the quasi-adiabatic process. The target nucleus is excited up to several hundred MeV energies close to the maximum of the level density. Photon-induced nucleon emission and neutron evaporation populate a range of daughter nuclei above the valley of stability. We expect that experimental data will shed light on the energy dependence of the level density at high excitation energies, and on the structure of proton-rich nuclei.
[1] G. Mourou and T. Tajima, Science 331 (2011) 41.
[2] H. A. Weidenmüller, Phys. Rev. Lett. 106 (2011) 122502.
[3] A. Pálffy and H. A. Weidenmüller, Phys. Lett. B (2012) in press.