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Electron Impact Ionization Close to the Threshold: Classical Calculations
In this paper we present Classical Trajectory Monte Carlo (CTMC) calculations
for single and multiple electron ionization of Argon atoms and ions in the
threshold region. We are able to recover the Wannier exponents a for the
power-law behavior of the cross section s versus excess energy: the exact value
of the exponent as well as the existence of its saturation for multiple
ionization appear to be related to how the total binding energy is shared
between target electrons.Comment: 9 pages. To be published in Journal of Physics
The lifetime cost of a magnetic refrigerator
The total cost of a 25 W average load magnetic refrigerator using commercial
grade Gd is calculated using a numerical model. The price of magnetocaloric
material, magnet material and cost of operation are considered, and all
influence the total cost. The lowest combined total cost with a device lifetime
of 15 years is found to be in the range \^{+++}$ refrigeration unit. In a
rough life time cost comparison between the magnetic refrigeration device and
such a unit we find similar costs, the former being slightly cheaper, assuming
the cost of the magnet can be recuperated at end of life.Comment: 17 pages, 17 figure
Nets of Subfactors
A subtheory of a quantum field theory specifies von~Neumann subalgebras
\aa(\oo) (the `observables' in the space-time region \oo) of the
von~Neumann algebras \bb(\oo) (the `fields' localized in \oo). Every local
algebra being a (type \III_1) factor, the inclusion \aa(\oo) \subset
\bb(\oo) is a subfactor. The assignment of these local subfactors to the
space-time regions is called a `net of subfactors'. The theory of subfactors is
applied to such nets. In order to characterize the `relative position' of the
subtheory, and in particular to control the restriction and induction of
superselection sectors, the canonical endomorphism is studied. The crucial
observation is this: the canonical endomorphism of a local subfactor extends to
an endomorphism of the field net, which in turn restricts to a localized
endomorphism of the observable net. The method allows to characterize, and
reconstruct, local extensions \bb of a given theory in terms of the
observables. Various non-trivial examples are given.Comment: Plain TeX, 32 pages. Several unnecessarily restrictive assumptions
have been relaxed. Proposition 4.10. has been reformulated in a more natural
way. Sect. 3 has been rearranged and a too general statement has been
adjusted. Some further minor change
A Canonical Ensemble Approach to the Fermion/Boson Random Point Processes and its Applications
We introduce the boson and the fermion point processes from the elementary
quantum mechanical point of view. That is, we consider quantum statistical
mechanics of canonical ensemble for a fixed number of particles which obey
Bose-Einstein, Fermi-Dirac statistics, respectively, in a finite volume.
Focusing on the distribution of positions of the particles, we have point
processes of the fixed number of points in a bounded domain. By taking the
thermodynamic limit such that the particle density converges to a finite value,
the boson/fermion processes are obtained. This argument is a realization of the
equivalence of ensembles, since resulting processes are considered to describe
a grand canonical ensemble of points. Random point processes corresponding to
para-particles of order two are discussed as an application of the formulation.
A statistics of a system of composite particles at zero temperature are also
considered as a model of determinantal random point processes.Comment: 26pages, Some typos are corrected, to be published in Commun. Math.
Phy
Annular objective apertures improve resolution of electron microscopes
Hollow-cone illumination techniques, using an annular objective aperture located behind back focal plane of objective lens, increase image contrast and minimize chromatic aberrations
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