Dynamical density functional theory for interacting Brownian particles: stochastic or deterministic?

We aim to clarify confusions in the literature as to whether or not dynamical density functional theories for the one-body density of a classical Brownian fluid should contain a stochastic noise term. We point out that a stochastic as well as a deterministic equation of motion for the density distribution can be justified, depending on how the fluid one-body density is defined -- i.e. whether it is an ensemble averaged density distribution or a spatially and/or temporally coarse grained density distribution.Comment: 10 pages, 1 figure, to be submitted to Journal of Physics A: Mathematical and Genera

Altitude dependence of fluorescence light emission by extensive air showers

Fluorescence light is induced by extensive air showers while developing in the Earth's atmosphere. The number of emitted fluorescence photons depends on the conditions of the air and on the energy deposited by the shower particles at every stage of the development. In a previous model calculation, the pressure and temperature dependences of the fluorescence yield have been studied on the basis of kinetic gas theory, assuming temperature-independent molecular collision cross-sections. In this work we investigate the importance of temperature-dependent collision cross-sections and of water vapour quenching on the expected fluorescence yield. The calculations will be applied to simulated air showers while using actual atmospheric profiles to estimate the influence on the reconstructed energy of extensive air showers.Comment: 8 pages, 18 figures, to be published in Proc. 5th Fluorescence Workshop, El Escorial - Madrid, Sept. 200

Scientific Preparations for Lunar Exploration with the European Lunar Lander

This paper discusses the scientific objectives for the ESA Lunar Lander Mission, which emphasise human exploration preparatory science and introduces the model scientific payload considered as part of the on-going mission studies, in advance of a formal instrument selection.Comment: Accepted for Publication in Planetary and Space Science 51 pages, 8 figures, 1 tabl

Dependence of direct neutron capture on nuclear-structure models

The prediction of cross sections for nuclei far off stability is crucial in the field of nuclear astrophysics. We calculate direct neutron capture on the even-even isotopes $^{124-145}$Sn and $^{208-238}$Pb with energy levels, masses, and nuclear density distributions taken from different nuclear-structure models. The utilized structure models are a Hartree-Fock-Bogoliubov model, a relativistic mean field theory, and a macroscopic-microscopic model based on the finite-range droplet model and a folded-Yukawa single-particle potential. Due to the differences in the resulting neutron separation and level energies, the investigated models yield capture cross sections sometimes differing by orders of magnitude. This may also lead to differences in the predicted astrophysical r-process paths. Astrophysical implications are discussed.Comment: 25 pages including 12 figures, RevTeX, to appear in Phys. Rev.