10,144 research outputs found
Cyclotrons with Fast Variable and/or Multiple Energy Extraction
We discuss the principle possibility of stripping extraction in combination
with reverse bends in isochronous separate sector cyclotrons (and/or FFAGs). If
one uses reverse bends between the sectors (instead of drifts) and places
stripper foils at the sector exit edges, the stripped beam has a reduced
bending radius and it should be able to leave the cyclotron within the range of
the reverse bend - even if the beam is stripped at less than full energy.
We are especially interested in -cyclotrons, which allow to double the
charge to mass ratio by stripping. However the principle could be applied to
other ions or ionized molecules as well. For the production of proton beams by
stripping extraction of an -beam, we discuss possible designs for three
types of machines: First a low-energy cyclotron for the simultaneous production
of several beams at multiple energies - for instance 15 MeV, 30 MeV and 70 MeV
- thus allowing to have beam on several isotope production targets. In this
case it is desired to have a strong energy dependence of the direction of the
extracted beam thus allowing to run multiple target stations simultaneously.
Second we consider a fast variable energy proton machine for cancer therapy
that should allow extraction (of the complete beam) at all energies in the
range of about 70 MeV to about 250 MeV into the same beam line. And third, we
consider a high intensity high energy machine, where the main design goals are
extraction with low losses, low activation of components and high reliability.
The price that has to be paid for these advantages is an increase in size
and/or in field strength compared to proton machines with standard extraction
at the final energy.Comment: 10 pages, 9 figure
Minkowski Spacetime and QED from Ontology of Time
Classical mechanics, relativity, electrodynamics and quantum mechanics are
often depicted as separate realms of physics, each with its own formalism and
notion. This remains unsatisfactory with respect to the unity of nature and to
the necessary number of postulates. We uncover the intrinsic connection of
these areas of physics and describe them using a common symplectic Hamiltonian
formalism. Our approach is based on a proper distinction between variables and
constants, i.e. on a basic but rigorous ontology of time. We link these concept
with the obvious conditions for the possibility of measurements. The derived
consequences put the measurement problem of quantum mechanics and the
Copenhagen interpretation of the quantum mechanical wavefunction into
perspective. According to our (onto-) logic we find that spacetime can not be
fundamental. We argue that a geometric interpretation of symplectic dynamics
emerges from the isomorphism between the corresponding Lie algebra and the
representation of a Clifford algebra. Within this conceptional framework we
derive the dimensionality of spacetime, the form of Lorentz transformations and
of the Lorentz force and fundamental laws of physics as the Planck-Einstein
relation, the Maxwell equations and finally the Dirac equation.Comment: 36 pages, 3 figures, several typos corrected, references with title
Old Game, New Rules: Rethinking The Form of Physics
We investigate the modeling capabilities of sets of coupled classical
harmonic oscillators (CHO) in the form of a modeling game. The application of
simple but restrictive rules of the game lead to conditions for an isomorphism
between Lie-algebras and real Clifford algebras. We show that the correlations
between two coupled classical oscillators find their natural description in the
Dirac algebra and allow to model aspects of special relativity, inertial
motion, electromagnetism and quantum phenomena including spin in one go. The
algebraic properties of Hamiltonian motion of low-dimensional systems can
generally be related to certain types of interactions and hence to the
dimensionality of emergent space-times. We describe the intrinsic connection
between phase space volumes of a 2-dimensional oscillator and the Dirac
algebra. In this version of a phase space interpretation of quantum mechanics
the (components of the) spinor wave-function in momentum space are abstract
canonical coordinates, and the integrals over the squared wave function
represents second moments in phase space. The wave function in ordinary
space-time can be obtained via Fourier transformation. Within this modeling
game, 3+1-dimensional space-time is interpreted as a structural property of
electromagnetic interaction. A generalization selects a series of Clifford
algebras of specific dimensions with similar properties, specifically also 10-
and 26-dimensional real Clifford algebras.Comment: 23 pages, no figure
A New Look at Linear (Non-?) Symplectic Ion Beam Optics in Magnets
We take a new look at the details of symplectic motion in solenoid and
bending magnets and rederive known (but not always well-known) facts. We start
with a comparison of the general Lagrangian and Hamiltonian formalism of the
harmonic oscillator and analyze the relation between the canonical momenta and
the velocities (i.e. the first derivatives of the canonical coordinates). We
show that the seemingly non-symplectic transfer maps at entrance and exit of
solenoid magnets can be re-interpreted as transformations between the canonical
and the mechanical momentum, which differ by the vector potential.
In a second step we rederive the transfer matrix for charged particle motion
in bending magnets from the Lorentz force equation in cartesic coordinates. We
rediscover the geometrical and physical meaning of the local curvilinear
coordinate system. We show that analog to the case of solenoids - also the
transfer matrix of bending magnets can be interpreted as a symplectic product
of 3 non-symplectic matrices, where the entrance and exit matrices are
transformations between local cartesic and curvilinear coordinate systems.
We show that these matrices are required to compare the second moment
matrices of distributions obtained by numerical tracking in cartesic
coordinates with those that are derived by the transfer a matrix method.Comment: 7 pages, 2 figure
California Health Care Market Report 2005
Examines relationships among providers, physicians, hospitals, and patients, differences in the way physicians and hospitals organize, and factors that have prompted hospitals, medical groups, and health plans to redefine their relationships
Israel\u27s Transboundary Water Disputes
As water is necessary to the function of life, it is imperative to understand the role of water in the politically turbulent Middle East. This paper will focus on Israel’s water disputes with her neighbors and how such disputes have either led to military confrontation, have been partially resolved, and otherwise continue to exist. As populations in the region are expected to increase, the need for water, already in short supply, will be magnified. Thus negotiations to settle water disputes and provide for equitable distribution of the water resources will become more contentious. This legal analysis of Israel’s water disputes will hopefully provide some guidance to the settlement of such issues in Israel’s future peace negotiations with the Syrians and Palestinians
International Outsourcing, the Nature of Tasks, and Occupational Stability – Empirical Evidence for Germany
Using a large administrative data set of individual employment histories in Germany, this paper studies how international outsourcing affects the individual risk of leaving the occupation. Moreover, a rich data set on tasks performed in occupations is used to better characterize the sources of worker vulnerability. While international service outsourcing is associated with an increase in overall stability, the impact of international material outsourcing is slightly negative. These effects, however, are not uniform but depend on the nature of tasks performed in the occupation. Higher intensities of non-routine and interactive tasks are associated with a more beneficial (or less adverse) impact of international outsourcing on occupational stability.Occupational stability, international outsourcing, duration analysis
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