Direct photon production from hadronic sources in high-energy heavy-ion collisions

The low $p_T$ direct photon production from a variety of the hadronic sources is studied within the microscopic HSD transport approach for p+C, p+Pb and Pb+Pb collisions at 160 A GeV. The direct photon emission from elementary hadronic scatterings as well as meson-meson bremsstrahlung are incorporated. The influence of in-medium effects such as a collisional broadening of the vector-meson spectral functions on the photon emission rate is found to be hardly observable in the final spectra which are dominated by bremsstrahlung type processes. The uncertainties in the subtraction of the 'background' from the photon decay of hadronic resonances inside the hot and dense fireball is investigated, additionally. Our findings are relevant for the interpretation and extraction of experimental data on direct photon production at low $p_T$.Comment: 25 pages, 10 figures, to be published in Phys. Rev.

Femtosecond energy transfer between chromophores in allophycocyanin trimers

Ultrafast energy-transfer processes in allophycocyanin (APC) trimers from Mastigocladus laminosus have been examined by a femtosecond absorption technique. Isotropic absorption recovery kinetics with τ=440±30 fs were observed in APC trimers at 615 nm. In APC monomers such a fast process was not observed. The anisotropy in both samples was constant and close to 0.4 during the first few picoseconds. The results are consistent with a model of the APC trimer in which the two APC chromophores have different absorption spectra with maxima about 600 and 650 nm. The transfer of energy from the 600 nm chromophore to the 650 nm chromophore occurs in 440 fs and is dominated by the Förster dipole—dipole energy-transfer mechanism

ПРОИСХОЖДЕНИЕ И СТРОЕНИЕ НИЖНЕЙ КОРЫ ОКЕАНОВ И ЗАДУГОВЫХ МОРЕЙ: СВИДЕТЕЛЬСТВА ПО ВПАДИНЕ МАРКОВА (СРЕДИННО-АТЛАНТИЧЕСКИЙ ХРЕБЕТ) И ВОЙКАРСКОЙ ОФИОЛИТОВОЙ АССОЦИАЦИИ (ПОЛЯРНЫЙ УРАЛ)

The Markov Deep (the axial part of the slow-spreading Mid-Atlantic Ridge, 6°N, Sierra Leone oceanic core complex) and the Paleozoic Voikar ophiolite association (Polar Urals) formed in the back-arc sea conditions. In both cases, the lower crust of a close structure was formed on the basements composed ofdepleted peridotites of the ancient lithospheric mantle. The available data show that the composition of the lower crust of the oceans and back-arc seas is dominated by layeredmafic-ultramafic intrusions originating from the MORB melts, and suggest a similar asthenospheric source of magmas. Sills and dykes formed from other magma sources represent the second structural element of the lower oceanic crust: in case of the ocean, mainly ferrogabbroids originating from specific melts with the OIB involvement, and, in case of the back-sea sea, gabbro-norites of the supra-subduction calc-alkaline series. In both cases, the upper crust originates frombasaltic flows that occurred later and are associated with new episodes in the tectonic development. According to [Sharkov, 2012], the development of slow-spreading ridges takes place in discrete impulses and non-simultaneously along their entire length. Furthermore, oceanic core complexes (OCC) in their axial parts are the ridge segments, where spreading is resumed. At the OCC stage, newly formed basalt melts move upwards from the magma generation zone into fractures (dykes) through the lithospheric mantle, and the thickness of the lower crust is built up by sills. As spreading develops in this area, the crust becomes thicker from below due to underplating in form of large layered intrusions. The newly formed restites, in their turn, cause an increase in the lithospheric mantle thickness from below. Apparently, the lower crust formed in the back-arc seas according to a similar scenario, although complicated by the processes taking place in the subduction zone.На примере впадины Маркова (осевая часть медленно-спредингового Срединно-Атлантического хребта, 6° с.ш., внутренний океанический комплекс Сьерра-Леоне) и палеозойской Войкарской офиолитовой ассоциации (Полярный Урал), формировавшейся в условиях задугового моря, показано, что в обоих случаях нижняя кора имеет сходное строение и формировалась на фундаменте, сложенном деплетированными перидотитами древней литосферной мантии. Согласно имеющимся данным, ведущую роль в составе нижней коры океанов и задуговых морей играют расслоенные мафит-ультрамафитовые интрузивы, произошедшие из расплавов типа MORB, что предполагает сходный астеносферный источник магм. Вторым элементом строения нижней океанической коры являются силлы и дайки, образовавшиеся за счет других источников магм. В случае океана они сложены преимущественно феррогабброидами, произошедшими за счет специфических расплавов с участием OIB, а в задуговом море – габбро-норитами надсубдукционной известково-щелочной серии. Верхняя кора в обоих случаях образована более поздними излияниями базальтов, связанными с новыми эпизодами развития этих тектонических структур. Как было показано ранее [Sharkov, 2012], развитие медленно-спрединговых хребтов происходит дискретными пульсами и не одновременно по всей их длине. При этом внутренние океанические комплексы (ВОК) в их осевых частях как раз и представляют cобой сегменты хребта, где происходит возобновление спрединга. На стадии формирования ВОК новообразованный базальтовый расплав поднимается из зоны генерации магм по трещинам (дайкам) сквозь литосферную мантию и наращивает существующую нижнюю кору в форме силлов, а по мере развития на данном участке зоны спрединга - снизу, путем андерплейтинга в форме крупных расслоенных интрузивов; новообразованные реститы, в свою очередь, наращивают снизу литосферную мантию. Образование нижней коры в задуговых морях, по-видимому, происходило по сходному сценарию, но осложнялось процессами в зоне субдукции.

High energy density physics with intense ion and laser beams

We will present the status and perspectives of High Energy Density Physics (HEDP) with intense heavy ion beams as a tool to induce extreme states of matter..

VIOLATION OF INFORMATION ECOLOGY IN MEDIA SPACE

The extreme “pollution” of the global information space has a negative impact on the social well-being of the population for media space is a kind of social space covered by the media. It is necessary to create an effective system of legal protection and social guarantees so that any citizen can receive minimal social protection and be protected from the negative impact of the adverse ecology of the mass media. Not everyone who is experiencing intense exposure to the media is aware of its negative effects including “fatigue syndrome”. To prevent it, D. Lewis proposes the following algorithm: use all information technologies of business and everyday communication; improve the methods of studying and processing data; set the right priorities for their analysis and use [26]. All media and actors that interact with them must master information culture, for which it is necessary to train specialists in the field of media ecology who are aware of the influence of media and social technologies on people’s feelings, thoughts, values and behavior. So far, experts on media ecology do not have a sufficient theoretical basis for conducting sociological research and identifying how the media forces the audience to structure what it sees, hears and feels in a certain way. Today’s media (especially electronic) can have a violent and undesirable effect - this is not only a psychological but also a philosophical, social and cultural problem that affects both children and adults. “Information anarchy” leads not only to moderate negative consequences but in some cases to “information ecocide” - destruction of traditional information and the media. Countering the contamination of the information environment should include the following steps: development of requirements for the content creation; monitoring of the collection, storage, processing and destruction of information; development of criteria for assessing the use of information. It is necessary to introduce a single rating system for information products, which will allow users to evaluate the quality of information sources according to the following criteria: purity of information; work on creating content; source coverage; quality (completeness) of information; sources of specific data sets; social-demographic characteristics of potential users

Ion stopping in dense plasma target for high energy density physics

The basic physics of nonrelativistic and electromagnetic ion stopping in hot and ionized plasma targets is thoroughly updated. Corresponding projectile-target interactions involve enhanced projectile ionization and coupling with target free electrons leading to significantly larger energy losses in hot targets when contrasted to their cold homologues. Standard stoppping formalism is framed around the most economical extrapolation of high velocity stopping in cold matter. Further elaborations pay attention to target electron coupling and nonlinearities due to enhanced projectile charge state, as well. Scaling rules are then used to optimize the enhanced stopping of MeV/amu ions in plasmas with electron linear densities nel ~ 10 18 -10 20 cm -2 . The synchronous firing of dense and strongly ionized plasmas with the time structure of bunched and energetic multicharged ion beam then allow to probe, for the first time, the long searched enhanced plasma stopping and projectile charge at target exit. Laser ablated plasmas (SPQR1) and dense linear plasma columns (SPQR2) show up as targets of choice in providing accurate and on line measurements of plasma parameters. Corresponding stopping results are of a central significance in asserting the validity of intense ion beam scenarios for driving thermonuclear pellets. Other applications of note feature thorium induced fission, novel ion sources and specific material processing through low energy ion beams. Last but not least, the given ion beam-plasma target interaction physics is likely to pave a way to the production and diagnostics of warm dense matter (WDM)

Multiply charged ions from iodine laser-produced plasma of medium- and high-Z targets

Maximum charge states of ions registered in the far expansion zone from laser-produced plasma of Al, Co, Ni, Cu, Ta, W, Pt, Au, Pb, and Bi are presented. The Thomson parabola spectrometer was used to display a general view of the ion species of an expanding plasma while detailed ion charge-energy spectra were determined by the cylindrical electrostatic ion energy analyzer. The current densities of highly charged ion groups above 20 mA/cm2 were measured by use of an ion collector at a distance of 1 m from the target. The photodissociation iodine laser system PERUN (λ = 1.315 μm, power density up to 1015 W cm−2) was employed as a drive