The coulomb glory effect in collisions of antiprotons with heavy ions

The Coulomb glory effect in the back scattering of antiprotons with energies of from 100 eV to 3 keV from a bare nucleus of uranium and from uranium ions with closed shells is considered in terms of nonrelativistic and relativistic quantum theory. The appearance of Coulomb glory in collisions with multiply charged ions is caused by nucleus charge screening by filled electron shells. In scattering from a bare nucleus, the effect appears because of the screening properties of the vacuum polarization potential.     

Radiative losses of alpha particles on heavy ions in fusion plasma

A new channel of radiative losses in fusion plasma with impurities of multielectron ions associated with their excitation by fast alpha particles has been studied. It has been shown that this loss channel for tungsten impurity is comparable with standard radiative losses of plasma electrons.     

The two-dimensional coulomb gas in the critical region

We consider the two-dimensional Coulomb gas in the critical region. To avoid the well-known collapse of the system below a certain temperature, the Coulomb interaction is cut inside a core radius. By analysis of the pair correlation function we find that this system exhibits a phase transition with a critical point. Below the critical temperature the ions are unable to shield each other, and they all may be considered as bound in neutral dipolar pairs. The density of dipolar pairs affects the critical temperature. In the critical region we obtain explicit results, and we are able to extract the leading singular behavior of the pair correlation function.     

Electron acceleration via collisions with ions in plasma under the action of a relativistically strong laser field

Electron-ion collisions in plasma in a strong electromagnetic field are considered in the ultrarelativistic limit (in which the vector potential A is such that a = eA/mc ² ? 1). Expressions relating the electron drift coordinates and momentum to those in the laboratory frame are obtained using exact canonical transformations with allowance for adiabatic effects. The appearance of ultrafast particles with a maximum energy proportional to the third power of the laser pulse vector potential is predicted. Expressions for the energy (and number) distribution function of such high-energy (hot) electrons appearing as a result of electron-ion collisions are obtained. These distribution functions obey a power law, which agrees with the results recently obtained by Mangles et al. [1] in experiments with a petawatt laser.     

Possibility of observing dark matter via the gyromagnetic Faraday effect

If dark matter consists of cold, neutral particles with a nonzero magnetic moment, then, in the presence of an external magnetic field, a measurable gyromagnetic Faraday effect becomes possible. This enables direct constraints on the nature and distribution of such dark matter through detailed measurements of the polarization and temperature of the cosmic-microwave background radiation.     

Charge states of heavy ions, as determined from the parameters of solar energetic particle spectra

The charge states of He, C, O, and Fe ions are determined for 51 gradual solar energetic particle (SEP) events of solar cycle 23 using the parameters of the particle energy spectra consisting of two power-law regions separated by the so-called knee. Experimental data from the GOES satellites (protons) and ULEIS (all particles) and SIS (H, C, O, Fe ions) instruments are employed. The charge states of the heavy ions are found to be independent of the SEP event magnitude and particle energy (in the interval of 0.3 to 30 MeV/nucleon).     

Fullerene formation in the tracks of energetic ions

Abstract

Chromatographic analyses of solvent extracts from graphite bombarded with 130MeV/amu ¹⁶¹Dy²²⁺ ions, and polyimide (kapton) bombarded with 5 MeV ⁶Li¹⁺ ions, give clear evidence for the in situ synthesis of buckminsterfullerene -C₆₀. The role played by the production of highly confined, dense assemblies of energetic electrons in this phase change is discussed.     

Effects of the diffusive acceleration of particles by shock waves in the primordial matter of the solar system

The effects of the shock wave diffusive acceleration of particles are considered in the case of formation of isotopic relations of the anomalous Xe-HL component of xenon in relic grains of nanodiamonds in chondrites. It is shown that this component could be formed and captured simultaneously with the nanodiamond synthesis in the conditions of the explosive shock wave propagation from supernova outbursts. The specificity of isotopic composition of Xe-HL is due to the high hardness of the spectrum of nuclear-active particles at the shock wave front and its enrichment with heavy isotopes. The spallogenic nature of both the anomalous and normal components of xenon is ascertained, and the role of the subsequent evolutionary processes in the change of their isotopic systems is shown. Experimental evidence of the formation of the power law spectrum of particles with the spectral index γ ∼ 1 by the supersonic turbulence during the carbon-detonation supernova SnIa explosion is obtained; this perhaps opens new perspectives in studying the problem of the origin of cosmic rays. It is shown that at the stage of free expansion of the explosive shock wave, the degree of compression of the matter at the wave front was σ = 31 (the corresponding Mach number M ∼ 97); this led to a 31-fold increase of the magnetic field as well as of the maximum energy of accelerated particles, so that even the energy of protons reached ∼ 3 × 10¹⁵ eV, i.e., the “knee” region.     

Mean velocity of particles ejected from various polycrystalline metal surfaces by sputtering with high energetic noble gas ions

Preliminary results of the measurements are presented. The mean velocity was determined in dependence on the ion energy and showed a characteristic decrease at a certain ion energyE _o which is in accordance with a proposition of Seitz on the influence of inelastic energy losses. Additional measurements were carried out using a thermocouple as an universal radiation detector and they showed a corresponding increase in radiation power at the same energy value.     

Test mass charging simulation of ASTROD I due to solar energetic particles at 0.5 AU

Maintaining the geodesic motion of the test mass is vital to ASTROD I space mission. However,the electrostatic charging of the test mass due to cosmic rays and solar energetic particles will result in Coulomb and Lorentz forces and consequently influence the test mass motions. To estimate the size of these effects,a credible simulation of test mass charging processes is critically required. Using the GEANT4 software toolkit,we have modeled the charging processes and predict how the ASTROD I test mass will charge positively at a rate of 217370 e + /s,due to solar energetic particles(SEPs) at～0.5 AU caused by the largest SEPs event on 29,September,1989. In addition to Monte Carlo uncertainty,an error of ±30% in the net charging rates was added to account for uncertainties in the spectra,physics and geometry models.     

Quantum manipulation of trapped ions in two dimensional coulomb crystals

We show that a large number of ions forming a 2D Coulomb crystal provides an almost ideal system for scalable quantum computation and quantum simulation. In particular, the coupling of the internal states to the motion of the ions transverse to the crystal plane allows one to implement two-qubit quantum gates. We analyze in detail the decoherence induced by anharmonic couplings, and show that very high gate fidelities can be achieved with current experimental setups.     

Angular distribution of copper atoms sputtered with energetic ions

Measurements of the angular distribution of copper atoms which are sputtered by noble gas ions within the energy range between 0.1 and 1 MeV have been carried out for different angles of ion incidence. The hemisphere over the target surface could be studied with a microphotometer inside the sputtering chamber and the distributions can be plotted in tri-dimensional diagrams. The results are in principle similar to those obtained at lower energies. The angle of maximum emission varies with ion energy and with the angle of incidence and can be related to the sputtering yield.     

Low-frequency sheath instability in a non-Maxwellian plasma with energetic ions

Spontaneous low-frequency oscillations have been observed in the circuit of a positively biased electrode when the ambient nonuniform plasma is irradiated by a microwave pulse of short duration, which is approximately equal to the ion-plasma period. The instability with its characteristic frequency below the ion-plasma frequency is driven by an accelerated ion component interacting with the sheath of the electrode. A qualitative model of the instability is suggested.     

Surface morphology changes of graphite irradiated with energetic helium ions

Implantation of helium ions into graphite has been found to produce surface features, which are discussed in terms of radiation damage as a function of depth into the material. Annealing and electron microscope studies show these surface features to be still well defined after annealing at 1500°C. The suggested interpretation is consistent with the large surface stress found in the surface layers of implanted materials.     

Kinetic theory of a system of coulomb particles in the weakly relativistic approximation

An analysis is made of the connection between the relativistic analogs of the Vlasov and Landau equations obtained by Bogolyubov's method and the corresponding relativistic kinetic equations. The H theorem is considered in the weakly relativistic approximation.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 99–101, May, 1980.We thank L. M. Kovrizhnykh, A. A. Rukhadze, I. P. Pavlotskii, and A. S. Sakharov for valuable discussions.