Open Systems Viewed Through Their Conservative Extensions

A typical linear open system is often defined as a component of a larger conservative one. For instance, a dielectric medium, defined by its frequency dependent electric permittivity and magnetic permeability is a part of a conservative system which includes the matter with all its atomic complexity. A finite slab of a lattice array of coupled oscillators modelling a solid is another example. Assuming that such an open system is all one wants to observe, we ask how big a part of the original conservative system (possibly very complex) is relevant to the observations, or, in other words, how big a part of it is coupled to the open system? We study here the structure of the system coupling and its coupled and decoupled components, showing, in particular, that it is only the system's unique minimal extension that is relevant to its dynamics, and this extension often is tiny part of the original conservative system. We also give a scenario explaining why certain degrees of freedom of a solid do not contribute to its specific heat.Comment: 51 page

On the Atomic Photoeffect in Non-relativistic QED

In this paper we present a mathematical analysis of the photoelectric effect for one-electron atoms in the framework of non-relativistic QED. We treat photo-ionization as a scattering process where in the remote past an atom in its ground state is targeted by one or several photons, while in the distant future the atom is ionized and the electron escapes to spacial infinity. Our main result shows that the ionization probability, to leading order in the fine-structure constant, $\alpha$, is correctly given by formal time-dependent perturbation theory, and, moreover, that the dipole approximation produces an error of only sub-leading order in $\alpha$. In this sense, the dipole approximation is rigorously justified.Comment: 25 page

CMS physics technical design report : Addendum on high density QCD with heavy ions

Peer reviewe

IR-SPECTROSCOPY OF PHENYLRADICALS IN HELIUMNANODROPLETS

Author Institution: Department of Physical Chemistry II, Ruhr-University Bochum, D-44780 Bochum, GermanyThe study of aryl radicals is of paramount importance for a different number of reasons. These reactive species are critical intermediates in reactions of explosives and combustion processes, in the generation and the deposition of soot and the formation of organic pollutants . Furthermore these species play an important role in the carcinogenesis and the photocyclic tumour therapy. Based on their high reactivity it is not possible to investigate those substances at room temperature. For this reason previous experimental studies were carried out by embedding the radicals in a low temperature argon matrix , . In the present experimental study we wanted to investigate phenyl radicals as a prototype for aryl radicals in helium nanodroplets. In contrast to measurements in an argon matrix (10 K) we were able to get temperatures as low as 0.37 K. Using azobenzene as a precursor the phenyl radicals are generated with the help of a home-made pyrolysis oven at temperatures in the 600 - 1100 K range. The optimization of the phenyl source was carried out by observing the efficiency of the pyrolysis according to changes of different experimental parameters. After obtaining formation of the reactive species and their incorporation into the ultracold helium droplets, the radicals were spectroscopically studied in the spectral region of 3045 cm$^{-1}$ - 3085 cm$^{-1}$