Diamond thin Film Detectors for Beam Monitoring Devices

Diamonds offer radiation hard sensors, which can be used directly in primary beams. Here we report on the use of a polycrystalline CVD diamond strip sensor as beam monitor of heavy ion beams with up to 2.10^9 lead ions per bunch. The strips allow for a determination of the transverse beam profile to a fraction of the pitch of the strips, while the timing information yields the longitudinal bunch length with a resolution of the order of a few mm.Comment: 6 pages, 7 figures, to appear in the Proceedings of the Hasselt Diamond Workshop (Hasselt, Belgium, Feb. 2006), v4: accidentally submitted figure, appearing at end, remove

Entropy optimisation for distributed detection systems

In the general framework of data fusion, detection theory allows to distinguish a finite set of situations from observations . Bayes and Neyman-Pearson criteria are generally used in order to develop optimal detection rules . Nevertheless, in some applications (in particular when the a priori probabilities Pjj = 0, 1 of the hypotheses are uncertain or when one of them is near zero), it could be interesting to consider the optimisation of the quantity of information which is relevant for the detection problem . This approach could be used in digital communication problems where the information quantity sent is more interesting than the information itself . For such systems, an entropy based criterion seems to be of interest . Using such a criterion, we recall the entropy optimisation results for centralised detection networks . Within the framework of parallel distributed detection, we suggest to optimise the local detectors without taking into account the fusion problem, that we optimize separately. The main interest of this approach is that its implementation is simple . We recall then the results of the simultaneous optimisation of the local detectors and of the fusion operator. We also use an informational criterion for the optimisation of serial distributed networks . Finally, the different optimisation results are compared on an illustrative example . This allows to underline the very interesting robustness properties with respect to rare events of the informational approach, as opposed to the classical one .Dans le contexte général de la fusion de données, la théorie de la détection permet de discriminer de façon optimale, à partir d'observations, un nombre fini de situations. Classiquement, les critères de Bayes et de Neyman-Pearson sont utilisés dans la littérature. Pourtant, dans certaines applications (en particulier lorsque les probabilités a priori Pj j = 0.1 des hypothèses sont mal connues, ou si l'une d'entre elles est proche de zéro), il pourrait s'avérer intéressant de baser le problème d'optimisation sur la quantité d'information pertinente pour le problème de détection. Cette approche pourrait notamment s'adapter aux problèmes de communication numérique où l'on s'intéresse davantage à la quantité d'information transmise, plutôt qu'à l'information elle-même. Pour de tels systèmes, un critère entropique peut être intéressant. En utilisant un tel critère, nous rappelons les résultats de l'optimisation entropique des architectures de détection centralisée. Dans le cadre de la détection décentralisée parallèle, nous proposons d'optimiser les détecteurs locaux sans prendre en compte le problème de la fusion, que nous optimisons séparément. L'intérêt principal de cette approche est qu'elle offre une solution simple à mettre en œuvre. Nous rappelons alors les résultats de l'optimisation simultanée des détecteurs locaux et de l'opérateur de fusion. Nous proposons également d'utiliser le critère informationnel dans le cadre de l'optimisation d'une architecture décentralisée série. Enfin, une comparaison des résultats de l'optimisation de toutes ces architectures sur un exemple illustratif nous permet de mettre en évidence des propriétés très intéressantes de robustesse vis-à-vis d'événements rares de l'approche informationnelle, contrairement à l'approche classique

Effect of differences in proton and neutron density distributions on fission barriers

The neutron and proton density distributions obtained in constrained Hartree-Fock-Bogolyubov calculations with the Gogny force along the fission paths of 232Th, 236U, 238U and 240Pu are analyzed. Significant differences in the multipole deformations of neutron and proton densities are found. The effect on potential energy surfaces and on barrier heights of an additional constraint imposing similar spatial distributions to neutrons and protons, as assumed in macroscopic-microscopic models, is studied.Comment: 5 pages in Latex, 4 figures in ep

Stability of bubble nuclei through Shell-Effects

We investigate the shell structure of bubble nuclei in simple phenomenological shell models and study their binding energy as a function of the radii and of the number of neutron and protons using Strutinsky's method. Shell effects come about, on the one hand, by the high degeneracy of levels with large angular momentum and, on the other, by the big energy gaps between states with a different number of radial nodes. Shell energies down to -40 MeV are shown to occur for certain magic nuclei. Estimates demonstrate that the calculated shell effects for certain magic numbers of constituents are probably large enough to produce stability against fission, alpha-, and beta-decay. No bubble solutions are found for mass number A < 450.Comment: 9 pages and 9 figures in the eps format include

Statistical fluctuations for the fission process on its decent from saddle to scission

We reconsider the importance of statistical fluctuations for fission dynamics beyond the saddle in the light of recent evaluations of transport coefficients for average motion. The size of these fluctuations are estimated by means of the Kramers-Ingold solution for the inverted oscillator, which allows for an inclusion of quantum effects.Comment: 12 pages, Latex, 5 Postscript figures; submitted to PRC e-mail: [email protected] www home page: http://www.physik.tu-muenchen.de/tumphy/e/T36/hofmann.htm

Evidence for the Jacobi shape transition in hot 46Ti

The gamma-rays from the decay of the GDR in 46Ti compound nucleus formed in the 18O+28Si reaction at bombarding energy 105 MeV have been measured in an experiment using a setup consisting of the combined EUROBALL IV, HECTOR and EUCLIDES arrays. A comparison of the extracted GDR lineshape data with the predictions of the thermal shape fluctuation model shows evidence for the Jacobi shape transition in hot 46Ti. In addition to the previously found broad structure in the GDR lineshape region at 18-27 MeV caused by large deformations, the presence of a low energy component (around 10 MeV), due to the Coriolis splitting in prolate well deformed shape, has been identified for the first time.Comment: 8 pages, 4 figures, proceedings of the COMEX1 conference, June 2003, Paris; to be published in Nucl. Phys.

Accelerated Event-by-Event Neutrino Oscillation Reweighting with Matter Effects on a GPU

Oscillation probability calculations are becoming increasingly CPU intensive in modern neutrino oscillation analyses. The independency of reweighting individual events in a Monte Carlo sample lends itself to parallel implementation on a Graphics Processing Unit. The library "Prob3++" was ported to the GPU using the CUDA C API, allowing for large scale parallelized calculations of neutrino oscillation probabilities through matter of constant density, decreasing the execution time by a factor of 75, when compared to performance on a single CPU.Comment: Final Update: Post submission update Updated version: quantified the difference in event rates for binned and event-by-event reweighting with a typical binning scheme. Improved formatting of reference

A Dirac-Hartree-Bogoliubov approximation for finite nuclei

We develop a complete Dirac-Hartree-Fock-Bogoliubov approximation to the ground state wave function and energy of finite nuclei. We apply it to spin-zero proton-proton and neutron-neutron pairing within the Dirac-Hartree-Bogoliubov approximation (we neglect the Fock term), using a zero-range approximation to the relativistic pairing tensor. We study the effects of the pairing on the properties of the even-even nuclei of the isotopic chains of Ca, Ni and Sn (spherical) and Kr and Sr (deformed), as well as the $N$=28 isotonic chain, and compare our results with experimental data and with other recent calculations.Comment: 43 pages, RevTex, 13 figure

Leishmania Promastigotes Lack Phosphatidylserine but Bind Annexin V upon Permeabilization or Miltefosine Treatment

The protozoan parasite Leishmania is an intracellular pathogen infecting and replicating inside vertebrate host macrophages. A recent model suggests that promastigote and amastigote forms of the parasite mimic mammalian apoptotic cells by exposing phosphatidylserine (PS) at the cell surface to trigger their phagocytic uptake into host macrophages. PS presentation at the cell surface is typically analyzed using fluorescence-labeled annexin V. Here we show that Leishmania promastigotes can be stained by fluorescence-labeled annexin V upon permeabilization or miltefosine treatment. However, combined lipid analysis by thin-layer chromatography, mass spectrometry and 31 P nuclear magnetic resonance (NMR) spectroscopy revealed that Leishmania promastigotes lack any detectable amount of PS. Instead, we identified several other phospholipid classes such phosphatidic acid, phosphatidylethanolamine; phosphatidylglycerol and phosphatidylinositol as candidate lipids enabling annexin V staining.FAZIT (AW)Research Training Group 1121 of the German Research FoundationCarlsberg FoundationCenter for Synthetic Biology at Copenhagen UniversityUNIK research initiative of the Danish Ministry of Science, Technology and Innovatio