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Hybrid atomic models for spectroscopic plasma diagnostics
We propose a hybrid approach to treating atomic structure and rates in collisional-radiative models, combining the completeness of highly averaged models with the accuracy of detailed models. The hybrid scheme supplements a small subset of coronally accessible fine structure levels with a complete set of configuration- and superconfiguration-averaged levels and produces spectra based on transitions among a mix of fine-structure and relativistic configuration-averaged levels. Convenient expressions are given for obtaining rates between the fine structure and averaged levels and a technique for propagating configuration interaction from the fine structure calculations to configuration averages is described. We present results from a trial hybrid model of germanium which demonstrate the accuracy of the hybrid model for charge state distributions and spectra
Monetary Resident Incentives: Effect on Patient Satisfaction in an Academic Emergency Department
Patient satisfaction most be a priority in emergency departments (EDs). The care provided by residents forms much of the patient contact in academic EDs
Chaos and localization in the wavefunctions of complex atoms NdI, PmI and SmI
Wavefunctions of complex lanthanide atoms NdI, PmI and SmI, obtained via
multi-configuration Dirac-Fock method, are analyzed for density of states in
terms of partial densities, strength functions (), number of principal
components () and occupancies (\lan n_\alpha \ran^E) of single
particle orbits using embedded Gaussian orthogonal ensemble of one plus
two-body random matrix ensembles [EGOE(1+2)]. It is seen that density of states
are in general multi-modal, 's exhibit variations as function of the
basis states energy and 's show structures arising from localized
states. The sources of these departures from EGOE(1+2) are investigated by
examining the partial densities, correlations between , and
\lan n_\alpha \ran^E and also by studying the structure of the Hamiltonian
matrices. These studies point out the operation of EGOE(1+2) but at the same
time suggest that weak admixing between well separated configurations should be
incorporated into EGOE(1+2) for more quantitative description of chaos and
localization in NdI, PmI and SmI.Comment: There are 9 figure
A Holder Continuous Nowhere Improvable Function with Derivative Singular Distribution
We present a class of functions in which is variant
of the Knopp class of nowhere differentiable functions. We derive estimates
which establish \mathcal{K} \sub C^{0,\al}(\R) for 0<\al<1 but no is pointwise anywhere improvable to C^{0,\be} for any \be>\al.
In particular, all 's are nowhere differentiable with derivatives singular
distributions. furnishes explicit realizations of the functional
analytic result of Berezhnoi.
Recently, the author and simulteously others laid the foundations of
Vector-Valued Calculus of Variations in (Katzourakis), of
-Extremal Quasiconformal maps (Capogna and Raich, Katzourakis) and of
Optimal Lipschitz Extensions of maps (Sheffield and Smart). The "Euler-Lagrange
PDE" of Calculus of Variations in is the nonlinear nondivergence
form Aronsson PDE with as special case the -Laplacian.
Using , we construct singular solutions for these PDEs. In the
scalar case, we partially answered the open regularity problem of
Viscosity Solutions to Aronsson's PDE (Katzourakis). In the vector case, the
solutions can not be rigorously interpreted by existing PDE theories and
justify our new theory of Contact solutions for fully nonlinear systems
(Katzourakis). Validity of arguments of our new theory and failure of classical
approaches both rely on the properties of .Comment: 5 figures, accepted to SeMA Journal (2012), to appea
Electron recombination with multicharged ions via chaotic many-electron states
We show that a dense spectrum of chaotic multiply-excited eigenstates can
play a major role in collision processes involving many-electron multicharged
ions. A statistical theory based on chaotic properties of the eigenstates
enables one to obtain relevant energy-averaged cross sections in terms of sums
over single-electron orbitals. Our calculation of the low-energy electron
recombination of Au shows that the resonant process is 200 times more
intense than direct radiative recombination, which explains the recent
experimental results of Hoffknecht {\em et al.} [J. Phys. B {\bf 31}, 2415
(1998)].Comment: 9 pages, including 1 figure, REVTe
Isotope shift in the electron affinity of chlorine
The specific mass shift in the electron affinity between ^{35}Cl and ^{37}Cl
has been determined by tunable laser photodetachment spectroscopy to be
-0.51(14) GHz. The isotope shift was observed as a difference in the onset of
the photodetachment process for the two isotopes. In addition, the electron
affinity of Cl was found to be 29138.59(22) cm^{-1}, giving a factor of 2
improvement in the accuracy over earlier measurements. Many-body calculations
including lowest-order correlation effects demonstrates the sensitivity of the
specific mass shift and show that the inclusion of higher-order correlation
effects would be necessary for a quantitative description.Comment: 16 pages, 6 figures, LaTeX2e, amsmat
Setting up a Common European Asylum System : Report on the application of existing instruments and proposals for the new system
The study assesses firstly the evaluation process of the first generation of asylum instruments while underlining the possibilities to improve it. It analyses secondly the asylum "acquis" regarding distribution of refugees between Member States, the eligibility for protection, the status of protected persons regarding detention and vulnerability, asylum procedures and the external dimension by formulating short-term recommendations of each area. Its last part is devoted to the long term evolution of the Common European Asylum System regarding the legal context including the accession of the EU to the Geneva Convention, the institutional perspectives including the new European Support Office, the jurisdictional perspective, the substantive perspective, the distributive perspective and the external perspective
Measurement and application of electron stripping of ultrarelativistic
New measurements of the stripping cross-section for ultrarelativistic
hydrogen-like lead ions passing through aluminium and silicon have been
performed at the Advanced Wakefield experiment at CERN. Agreement with existing
measurements and theory has been obtained. Improvements in terms of electron
beam quality and ion beam diagnostic capability, as well as further
applications of such an electron beam, are discussed
RADIO-FREQUENCY MULTIPACTING AS QUALITY CONTROL OF COATINGS FOR E-CLOUD SUPPRESSION
Abstract To mitigate electron cloud in particle accelerators a carbon coating with low SEY (Secondary Electron Yield) has been developed. In the case of the SPS (Super Proton Synchrotron), which belongs to the LHC injector chain, testing of the performance of coated beam pipes directly in the accelerator must cope with the schedule of the regular machine operation. For this reason an alternative tool based on RF induced multipacting in a coaxial configuration has been designed for ex-situ characterization of the main bending dipoles of the SPS. In this contribution we report the results obtained before and after coating for two 6.4 meter dipoles with different cross sections of the vacuum chambers. The multipacting is monitored by measuring the pressure rise and the RF reflected power. After coating, the power threshold to induce multipacting is strongly reduced indicating a lower propensity for electron cloud. The impact of the RF coupling on the sensitivity of the technique is discussed. EXPERIMENTAL SETUP A SPS dipole can be transformed into a coaxial resonator by stretching a tungsten wire within its beam pipe. The RF excitation is generated by a Vector Network Analyser, (VNA), amplified and injected through one extremity of the wire while the other extremity is short circuited. By choosing a frequency corresponding to one of the resonances of this system, most of the RF power injected is dissipated in the resonator and only a small fraction reflected. In case of multipacting, a cloud of electrons is generated and the RF power is strongly reflected by the resulting plasma. To determine the power threshold for multipacting we ramp up the RF power while monitoring the ratio between the reflected and input power in the VNA. In the absence of multipacting this ratio remains constant, but rises abruptly when the multiplication of electrons starts. To complement the RF diagnostic, the vacuum is monitored by a total pressure gauge and a Residual Gas Analyser (RGA). More details about the experimental set-up can be found in MEASUREMENT IN THE DIPOLES BEFORE AND AFTER COATING The propensity of the beam pipes to multipact depends on their geometry, the SEY of their internal surfaces and the applied magnetic field. In the SPS the vacuum chambers of the two main types of bending dipoles, MBA and MBB, are made of 316LN stainless steel and have almost rectangular cross sections, but different internal dimensions (see Before coating, the MBB dipole has a lower power threshold for multipacting, (~1 dBW), compared to that of the MBA, (~4 dBW), and a higher maximum of the ratio reflected/input power than the MBA. This higher propensity to multipact of the MBB is attributed to the difference in the geometry and is in agreement with the outcome of electron cloud simulations done by Rumol
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