cyclotrons

vimeo

Cyclotone [Spin-up Finale] from Paul Prudence on Vimeo.

Real-time audio-visual performance work created in 2012.
Sound design and generative video synthesis by Paul Prudence.

Stills of the piece can be found here:
flickr.com/photos/transphormetic/sets/72157631734577958/with/8406356722/

Cyclotron [intro] can be found here:
vimeo.com/58144326

[ Authors ]
J.-C. David
[ Abstract ]
The spallation reactions are a type of nuclear reaction which occur in space by interaction of the cosmic rays with interstellar bodies. The first spallation reactions induced with an accelerator took place in 1947 at the Berkeley cyclotron (University of California) with 200 MeV deuterons and 400 MeV alpha beams. They highlighted the multiple emission of neutrons and charged particles and the production of a large number of residual nuclei far different from the target nuclei. The same year R. Serber describes the reaction in two steps: a first and fast one with high-energy particle emission leading to an excited remnant nucleus, and a second one, much slower, the de-excitation of the remnant. In 2010 IAEA organized a worskhop to present the results of the most widely used spallation codes within a benchmark of spallation models. If one of the goals was to understand the deficiencies, if any, in each code, one remarkable outcome points out the overall high-quality level of some models and so the great improvements achieved since Serber. Particle transport codes can then rely on such spallation models to treat the reactions between a light particle and an atomic nucleus with energies spanning from few tens of MeV up to some GeV. An overview of the spallation reactions modeling is presented in order to point out the incomparable contribution of models based on basic physics to numerous applications where such reactions occur. Validations or benchmarks, which are necessary steps in the improvement process, are also addressed, as well as the potential future domains of development. Spallation reactions modeling is a representative case of continuous studies aiming at understanding a reaction mechanism and which end up in a powerful tool.

[ Authors ]
Philip J.W. Moll, Nityan L. Nair, Tony Helm, Andrew C. Potter, Itamar Kimchi, Ashvin Vishwanath, James G. Analytis
[ Abstract ]
Dirac semi-metals show a linear electronic dispersion in three dimension described by two copies of the Weyl equation, a theoretical description of massless relativistic fermions. At the surface of a crystal, the breakdown of fermion chirality is expected to produce topological surface states without any counterparts in high-energy physics nor conventional condensed matter systems, the so-called “Fermi Arcs”. Here we present Shubnikov-de Haas oscillations involving the Fermi Arc states in Focused Ion Beam prepared microstructures of Cd$_3$As$_2$. Their unusual magnetic field periodicity and dependence on sample thickness can be well explained by recent theoretical work predicting novel quantum paths weaving the Fermi Arcs together with chiral bulk states, forming “Weyl orbits”. In contrast to conventional cyclotron orbits, these are governed by the chiral bulk dynamics rather than the common momentum transfer due to the Lorentz force. Our observations provide evidence for direct access to the topological properties of charge in a transport experiment, a first step towards their potential application.

[ Authors ]
F. Fuerst, K. Pottschmidt, H. Miyasaka, V. Bhalerao, M. Bachetti, S. E. Boggs, F. E. Christensen, W. W. Craig, V. Grinberg, C. J. Hailey, F. A. Harrison, J. A. Kennea, F. Rahoui, D. Stern, S. P. Tendulkar, J. A. Tomsick, D. J. Walton, J. Wilms, W. W Zhang
[ Abstract ]
We present spectral analysis of NuSTAR and Swift observations of Cep X-4 during its outburst in 2014. We observed the source once during the peak of the outburst and once during the decay, finding good agreement in the spectral shape between the observations. We describe the continuum using a powerlaw with a Fermi-Dirac cutoff at high energies. Cep X-4 has a very strong cyclotron resonant scattering feature (CRSF) around 30 keV. A simple absorption-like line with a Gaussian optical depth or a pseudo-Lorentzian profile both fail to describe the shape of the CRSF accurately, leaving significant deviations at the red side of the line. We characterize this asymmetry with a second absorption feature around 19 keV. The line energy of the CRSF, which is not influenced by the addition of this feature, shows a small but significant positive luminosity dependence. With luminosities between (1-6)e36 erg/s, Cep X-4 is below the theoretical limit where such a correlation is expected. This behavior is similar to Vela X-1 and we discuss parallels between the two systems.

Rencontre Hollande-Castro à Cuba : de quoi rire ?

See on Scoop.it - Politique : Place à la dure réalité et aux petits arrangements entres amis “AutreMent”

Au moins, il rit. Au moins ça. Il y a eu la fatigue du voyage, les confettis de l’empire avalés un par un, en chapelet, aéroport, gerbe, aéroport, gerbe, les préfets tout en blanc, les Martiniquaises endimanchées, il y a eu la gaffe de la dette d’Haïti, trop fort, la gaffe de la dette d’Haïti – quels naïfs tout de même ces Caraïbes, et dire qu’ils y ont cru, même cinq minutes –, il y a eu cette brassée de promesses qu’on sait qu’on ne tiendra pas, un cyclotron ici, un cyclotron là, il y a eu ce tourbillon dans lequel le temps fera le tri, et puis voici le point d’orgue, l’image que le temps gardera, la poignée de main au dictator Adidas Maximo, au monolithe, au Companero Survivante.


See on rue89.nouvelobs.com
ODYSSEO BY CAVALIA---IN THE REALM OF KUBRICK'S SPACE ODYSSEY

© Jim Clark

The Montreal-based spectacle concern, Cavalia, derives from a schism of sorts within the vastly successful Cirque du Soleil. Whereas the latter favors moments of incredible athleticism and contortion rather loosely bound to whimsical narrative, Cavalia is about very coherent fusion of dynamic instances to reveal an earthy cumulative wellspring. The performing horses constituting its most direct element are, in fact, only the most readily comprehended calling card for a multi-media cyclotron carrying us to depths of the sensual avant-garde.

The photo above entails bat-out-of-hell thundering motion, a human figure playing in concert with such dash; and the developmental elements of darkness, focused light and water.

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Aux Antilles, Hollande bataille pour le climat

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Dans le cadre de sa grande tournée caribéenne, François Hollande a parallèlement annoncé que la Martinique et la Guadeloupe seraient dotées chacune d’un cyclotron.



May 10, 2015 at 10:49AM
via Les Echos - actualité à la Une des Echos.fr http://ift.tt/1PakL8l