Superscaling predictions for neutrino-induced charged-current charged pion production at MiniBooNE

Superscaling approximation (SuSA) predictions to neutrino-induced charged-current charged pion production in the \Delta-resonance region are explored under MiniBooNE experimental conditions. The results obtained within SuSA for the flux-averaged double-differential cross sections of the \pi+ production for the \nu_\mu+CH_2 reaction as a function of the muon kinetic energy and of the scattering angle, the cross sections averaged over the angle, the total cross section for the \pi+ production, as well as CC1\pi+ to CCQE cross section ratio are compared with the corresponding MiniBooNE experimental data. The SuSA predictions are in good agreement with data on neutrino flux average cross-sections, but a somewhat different dependence on the neutrino energy is predicted than the one resulting from the experimental analysis.Comment: 15 pages, 6 figures, accepted for publication in Physics Letters

X-ray magnetic circular dichroism in d and f ferromagnetic materials: recent theoretical progress. Part I

The curreThe current status of theoretical understanding of the x-ray magnetic circular dichroism (XMCD) of 4 f and 5 f compounds is reviewed. Energy band theory based upon the local spin-density approximation (LSDA) describes the XMCD spectra of transition metal compounds with high accuracy. However, the LSDA does not suffice for lanthanide compounds which have a correlated 4 f shell. A satisfactory description of the XMCD spectra could be obtained by using a generalization of the LSDA, in which explicitly f electron Coulomb correlation are taken into account (LSDA + U approach). As examples of this group we consider GdN compound. We also consider uranium 5 f compounds. In those compounds where the 5 f electrons are rather delocalized, the LSDA describes the XMCD spectra reasonably well. As example of this group we consider UFe₂. Particular differences occur for the uranium compounds where the 5 f electrons are neither delocalized nor localized, but more or less semilocalized. Typical examples are UXAl (X = Co, Rh, and Pt), and UX (X = S, Se, Te). The semilocalized 5 f ’s are, however, not inert, but their interaction with conduction electrons plays an important role. We also consider the electronic structure and XMCD spectra of heavy-fermion compounds UPt₃, URu₂Si₂, UPd₂Al3₃, UNi₂Al₃, and UBe₁₃ where the degree of the 5 f localization is increased in comparison with other uranium compounds. The electronic structure and XMCD spectra of UGe₂ which possesses simultaneously ferromagnetism and superconductivity also presented. Recently achieved improvements for describing 5 f compounds are discussed

X-ray magnetic circular dichroism in Co₂FeGa: First-principles calculations

The electronic structure and x-ray magnetic circular dichroism (XMCD) spectra of the Heusler alloy Co₂FeGa were investigated theoretically from first principles, using the fully relativistic Dirac linear MT-orbital (LMTO) band structure method. Densities of valence states, orbital and spin magnetic moments are analyzed and discussed. The origin of the XMCD spectra in the Co₂FeGa compound is examined. The calculated results are compared with available experimental data

X-ray magnetic circular dichroism in d and f ferromagnetic materials: recent theoretical progress. Part I

The current status of theoretical understanding of the x-ray magnetic circular dichroism (XMCD) of 3d compounds is reviewed. Energy band theory based upon the local spin-density approximation (LSDA) describes the XMCD spectra of transition metal compounds reasonably well. Examples which we examine in detail are XPt₃ compounds (with X = V, Cr, Mn, Fe, Co, and Ni) in the AuCu₃ structure, Heusler compounds Co₂MnGe, Co₂NbSn, and compounds with noncollinear magnetic structure IrMnAl and Mn₃ZnC. Recently achieved improvements for describing the electronic and magnetic structures of 3d compounds are discussed

Antiproton-nucleus electromagnetic annihilation as a way to access the proton timelike form factors

Contrary to the reaction pbar + p --> e+ e- with a high momentum incident antiproton on a free target proton at rest, in which the invariant mass M of the (e+ e-) pair is necessarily much larger than the (pbar p) mass, in the reaction pbar + d --> n e+ e- the value of M can take values near or below the (pbar p) mass. In the antiproton-deuteron electromagnetic annihilation, this allows to access the proton electromagnetic form factors in the time-like region of q^2 near the (pbar p) threshold. We estimate the cross section dsigma(pbar +d --> e+ e- n)/dM for an antiproton beam momentum of 1.5 GeV/c. We find that near the (pbar p) threshold this cross section is about 1 pb/MeV. The case of heavy nuclei target is also discussed. Elements of experimental feasibility are presented for the process pbar + d --> n e+ e- in the context of the Panda project.Comment: 14 pages, 11 figures. submitted to EPJ

Beam instability stabilization in hybrid plasma waveguide

The authors submit the results of investigations of the beam-plasma instability derangement in the hybrid plasma waveguide. The latter, placed into the longitudinal magnetic field, consists of a chain of cavities connected inductively and its passage channel is filled with plasma. In this plasma, the excitation of low-frequency oscillations that belong to the low-hybrid resonance range is examined. The investigations are carried out in the beam-plasma oscillator. The plasma is generated and maintained due to the beam-plasma discharge.Приведені результати дослідження зриву пучково-плазмової нестійкості у гібридному плазмовому хвилеводі, розміщеному в поздовжньому магнітному полі, що складається з ланцюга індуктивно зв’язаних резонаторів, пролітний канал якого заповнений плазмою, при збудженні низькочастотних коливань в його плазмі із області нижнєгібридного резонансу зовнішнім генератором. Гібридний плазмовий хвилевід використовується в пучково-плазмовому генераторі. Плазма створюється і підтримується за рахунок пучково-плазмового розряду.Приведены результаты исследования срыва пучково-плазменной неустойчивости в гибридном плазменном волноводе, помещенном в продольное магнитное поле, состоящем из цепочки индуктивно связанных резонаторов, пролетный канал которой заполнен плазмой, при возбуждении низкочастотных колебаний в его плазме из области нижнегибридного резонанса внешним генератором. Гибридный плазменный волновод используется в пучково-плазменном генераторе. Плазма образовывается и поддерживается за счет пучково- плазменного разряда.The authors are grateful to A.P. Tolstolugsky for the calculation of the spiral aerial, loaded with plasma and to L.D. Lobzov for the oscillator adjustment. S.S. Pushkarev’s help in the elaboration of the technique of registering the probing pulses in plasma with probes is gratefully acknowledged. We also wish to thank V.A. Buts for the discussion of the results and valuable suggestions in the course of the work fulfillment

Electronic structure and magneto-optical Kerr effect in UCuAs₂

The optical and magneto-optical (MO) spectra of the ternary compound UCuAs₂ are investigated theoretically from first principles, using the fully relativistic Dirac linear-muffin-tin-orbital band structure method. The electronic structure is obtained with the local spin-density approximation (LSDA), as well as with the so-called LSDA+U approach. Better agreement between the theoretically calculated and the experimentally measured MO Kerr spectra is found with the LSDA+U approximation. The origin of the Kerr rotation in the compound is examined

Features of behavior of electrons of plasma in open trap in condition of transverse input of powerful microwave pulses at ECR

It has been experimentally shown that the effect of oscillations of large amplitude on the frequency of electron cyclotron resonance on a plasma held by a magnetic trap leads to an effective acceleration of the plasma electrons and the formation of directed electron fluxes, which in turn stimulate repeated microwave oscillations. A consequence of such a process is the appearance of alternating pulses of microwave oscillations in time.Експериментально показано, що вплив коливань великої амплітуди на частоті електронноциклотронного резонансу на плазму, що утримується магнітною пасткою, призводить до ефективного прискорення електронів плазми і формування направлених потоків електронів, які, в свою чергу, збуджують повторні НВЧ-коливання. Наслідком такого процесу є поява імпульсів НВЧ-коливань, які чергуються в часі.Экспериментально показано, что воздействие колебаний большой амплитуды на частоте электронноциклотронного резонанса на плазму, удерживаемою магнитной ловушкой, приводит к эффективному ускорению электронов плазмы и формированию направленных потоков электронов, которые, в свою очередь, возбуждают повторные СВЧ-колебания. Следствием такого процесса является появление чередующихся во времени импульсов СВЧ-колебаний

Exitation of highnumber harmonics by non-relativistic oscillators

The results of experimental researches of a possibility of an effective of high numbers harmonics radiation by nonrelativistic oscillators are represented. The good qualitative consent of experimental and theoretical results are obtained. In experiment the millionth harmonic was excited. It is shown, that the investigated mechanism can be used for excitation optical and ultra-violet radiation

Electronic structure and x-ray magnetic circular dichroism in (Ge,Mn)Te diluted magnetic semiconductors

The electronic structure of the (Ge,Mn)Te diluted magnetic semiconductors was investigated theoretically from first principles, using the fully relativistic Dirac linear muffin-tin orbital (LMTO) band structure method. The electronic structure is obtained with the local spin-density approximation (LSDA) as well as the LSDA+U method. The x-ray magnetic circular dichroism (XMCD) spectra of (Ge,Mn)Te DMSs at the Mn L2,3 edges are investigated theoretically from first principles. The origin of the XMCD spectra in the compound is examined. The calculated results are compared with available experimental data