Infrared cyclotron resonances in InSb at megagauss magnetic fields

Cyclotron resonance was studied in reflection in InSb at room temperature using pulsed magnetic fields of up to 1.4 MG and laser-obtained wavelengths of 10.6 and 5.56 μ. At 10.6μ, four resonances were found while one resonance was found at 5.56 μ.     

Magnet design and beam dynamics in computed fields for the DC-350 cyclotron

The DC-350 is an isochronous cyclotron designed in the Flerov Laboratory of Nuclear Reaction (FLNR). It is intended for accelerating ions with a mass-to-charge ratio A/Z within an interval of 5–10 and with an energy of 3–12 MeV/u at the extraction radius. These ion beams will be used in nuclear and applied physics experiments. The paper describes the results of a 3D magnet simulation. The cyclotron magnet and IM90 analiziting-bend magnet of the axial injection channel are studied here. The influence of correction coils on the cyclotron magnet is calculated. All magnet fields were calculated by MERMAID 3D code [1]. The text was submitted by the authors in English.     

Doppler-shifted cyclotron, doppleron-phonon, and pseudo-doppleron-phonon resonances in indium

Ultrasonic investigations have been carried out in geometry of the experiment corresponding to acoustic analogy of the Faraday effect with the use of a super pure crystal like indium. Lowering the temperature from 4.2 K to 1.28 K has revealed new peculiarities of in the magnetic field dependences of absorption and phase velocity of circularly polarized ultrasonic waves. The peculiarities have been interpreted as manifestation of multiple doppleron-phonon and Doppler-shifted cyclotron resonances. The discovery of these resonances has changed interpretation of some anomalies observed in the previous experiments.     

Overlapping of resonances and stochasticity of electron trajectories in cyclotron masers

When an electromagnetic (EM) wave has a large amplitude and electrons have a large energy, the electron cyclotron frequency in the process of interaction with an EM wave can vary significantly. This can lead to overlapping of cyclotron resonances at different harmonics. It is shown that such an overlapping causes the stochasticity of electron orbits. Estimates show that this effect can be present in relativistic gyrodevices currently under development for driving future accelerators.     

On the excitation of ion cyclotron and electron cyclotron waves by beams of charged particles

The instabilities of the electrostatic waves of a hot plasma in a magnetic field, excited by beams of charged particles, have been studied in some special cases within the framework of the linear theory. We are interested in short-wavelength oscillations with a transverse wavelength compareable with the Larmore radius of ions or electrons, with frequencies in the vicinity of the harmonic cyclotron frequency of ions or electrons. Expressions have been derived for the increments of these instabilities in the case of a beam with an isotropic distribution function in the velocity space, as well as with an anisotropic distribution function. The influence of the beam temperature on the character of the instabilities and the conditions of formation of the instabilities are discussed, and the order of magnitude of the increments is estimated.The authors thanks J. Václavík and V. Kopecký for valuable discussions and comments.     

Nonlinear dynamics of charged particles interacting with combined ac-dc electromagnetic fields

A nonlinear Lorenz model describing interactions between charged particles and combined ac-dc electromagnetic fields is studied for various combinations of frequencies, field strengths and relative angle (θ) between the ac and dc magnetic fields. Strong directional effects on the magnitude and location of resonant particle motion are observed when θ is varied and the regular resonance windows in the aligned field (θ = 0) and linear version of the model studied previously by Durney etaal., break up to form irregular and less well pronounced regions of large and small particle displacements when nonlinearities are taken into account. The length of time takne to achieve resonant behaviour also becomes larger and more variable when nonlinearities are present. The possible relevance of these effects to interactions between electromagnetic fields and biological media is briefly discussed.     

Optical absorption resonances of trapped particles

We have previously shown the possibility of the existence of a one-photon resonance with homogeneous width in the center of an absorption line of trapped particles. The results of a detailed investigation of this resonance are given in the first part of the present paper. The second part is devoted to a two-photon resonance in a standing-wave field: the time of coherent interaction with the field is increased for trapped particles, which permits the elimination of transit resonance broadening.     

The production of high-momentum particles and resonances in pp collisions at the CERN intersecting storage rings

Data are reported on the momentum distributions of Λ, Λ (1520), φ (1020), $\text{Λ}\text{and}\text{p}$, inclusively produced between 1° and 2° with respect to one of the primary proton beams at the CERN Intersecting Storage Rings. In addition, the decay angular distribution of the Λ(1520), the ratio of the cross sections for the production of Σ^? (1385) and Σ⁺ (1385) and the ratios among different charge states of the pairs Λπ, ΛK, Δ⁺⁺ (1232)π and ππ have been measured. These data are confronted with current ideas on fragmentation.     

Shifts of resonances in the presence of time-separated fields

A shift of resonance in the presence of time-separated fields due to the curvature of the wavefront of the field pulses is revealed. A scheme for the observation of resonances that allows the shift related to the recoil effect to be completely eliminated is proposed.     

Ultranarrow optical resonances in the presence of time-separated fields

Saturated populations of the lower (ground) and upper states of a two-level system, which interact with two pairs of oppositely directed light pulses, are determined. The effect of recoil momentum related to the spontaneous decay of the upper level is taken into account.     

Relativistic resonances in combined magnetic and laser fields

We propose a mechanism for experimental investigation of relativistic effects in the laser-atom interaction with moderate (nonrelativistic) laser intensities that involves placing the system in a static magnetic field parallel to the laser's magnetic-field component. The resonantly induced relativistic motion of the atomic electron leads to a variety of novel phenomena: a relativistic dephasing leading to a ringlike spatial probability density, a counterintuitive window of relativistically enhanced motion, and a sequence of sawtooth-shaped resonances that may increase the harmonic generation.     

Dielectric function and plasma resonances of small metal particles

Using the simple model of electrons in a box, a dielectric function is derived which should be appropriate for small metal particles. This dielectric function is used to examine quantum size effects in the optical absorption spectra. For very small particles of uniform size and shape, the plasma resonance absorption should shift and broaden and should show fine structure corresponding to transitions between discrete conduction band energy levels. The size dependence of the shift and broadening was measured and found to be in quantitative agreement with theory.     

Intersubband cyclotron combined resonances in 2D systems with anisotropic and tilted valleys

Lineshape of intersubband transitions is calculated in a surface space-charge layer on semiconductor whose constant-energy surfaces are ellipsoids arbitrarily oriented with respect to the surface. The case when magnetic field is normal to the surface is considered. Combined intersubband cyclotron transitions are allowed when ellipsoids are tilted with respect to the surface. The depolarization effect affects the combined transition differently from the main transition.