Numerical Simulation of Multicomponent Ion Beam from Ion Sources

A program library for numerical simulation of a multicomponent charged particle beam from ion sources is presented. The library is aimed for simulation of high current, low energy multicomponent ion beam from ion source through beamline and realized under the Windows user interface for the IBM PC. It is used for simulation and optimization of beam dynamics and based on successive and consistent application of two methods: the momentum method of distribution function (RMS technique) and particle in cell method. The library has been used to simulate and optimize the transportation of tantalum ion beam from the laser ion source (CERN) and calcium ion beam from the ECR ion source (JINR, Dubna)

Cyclotron resonance in a two-dimensional electron gas with long-range randomness

We show that the the cyclotron resonance in a two-dimensional electron gas has non-trivial properties if the correlation length of the disorder is larger than the de Broglie wavelength: (a) the lineshape assumes three different forms in strong, intermediate, and weak magnetic fields (b) at the transition from the intermediate to the weak fields the linewidth suddenly collapses due to an explosive growth in the fraction of electrons with a diffusive-type dynamics.Comment: A few typos correcte

Perturbative fragmentation

The Berger model of perturbative fragmentation of quarks to pions is improved by providing an absolute normalization and keeping all terms in a (1-z) expansion, which makes the calculation valid at all values of fractional pion momentum z. We also replace the nonrelativistic wave function of a loosely bound pion by the more realistic procedure of projecting to the light-cone pion wave function, which in turn is taken from well known models. The full calculation does not confirm the (1-z)^2 behavior of the fragmentation function (FF) predicted in for $z>0.5$, and only works at very large z>0.95, where it is in reasonable agreement with phenomenological FFs. Otherwise, we observe quite a different z-dependence which grossly underestimates data at smaller z. The disagreement is reduced after the addition of pions from decays of light vector mesons, but still remains considerable. The process dependent higher twist terms are also calculated exactly and found to be important at large z and/or pT.Comment: 10 pages, 8 figure

Large Rapidity Gap Processes in Proton-Nucleus Collisions

The cross sections for a variety of channels of proton-nucleus interaction associated with large gaps in rapidity are calculated within the Glauber-Gribov theory. We found inelastic shadowing corrections to be dramatically enhanced for such events. We employ the light-cone dipole formalism which allows to calculate the inelastic corrections to all orders of the multiple interaction. Although Gribov corrections are known to make nuclear matter more transparent, we demonstrate that in some instances they lead to an opaqueness. Numerical calculations are performed for the energies of the HERA-B experiment, and the RHIC-LHC colliders.Comment: 19 page

Клинический случай поражения молнией

Atmospheric electricity damage as a result of lightning strike is a relatively rare condition in intensive care medicine, however it can be accompanied by high mortality and serious complications in the majority of survived patients.The objective was to demonstrate a clinical case of lightning injury and discussion of diagnostic and treatment aspects in this condition.Materials and Methods. 18-yr old patient was delivered to hospital after lightning strike. She lost consciousness, there was no breathing for a short time, and the witnesses provided artificial respiration and external cardiac compressions. On admission, the signs of shock were present in parallel with dopamine infusion, the skin was pale-grey and cold, with traces of thermal damage according to the type of contact with metal of various localization on the neck, scalp, front surface of the chest and abdominal wall, in the groin, on the left foot. The patient was hospitalized to ICU, therapeutic and diagnostic measures were started. We revealed decompensated lactic acidosis, biochemical signs of myocardial and muscle damage. The infusion therapy, analgesics, antibiotics, proton pump inhibitors, anticoagulants were administered. During the therapy in the first 6 hours, the signs of shock were attenuated, in 4 days, the patient was transferred to traumatological department in a stable state. After the transfer from the ICU, hearing decline as well as pain and sensory disturbances in the left foot are persisting.Conclusion. An integrated approach is required in the diagnosis, treatment, and rehabilitation of patients with lightning injury.Поражение атмосферным электричеством в результате удара молнии – состояние, достаточно редко встречающееся в реанимационной практике; вместе с тем, оно сопровождается высокой смертностью и серьезными осложнениями у значительной части выживших пациентов.Цель – демонстрация клинического наблюдения поражения атмосферным электричеством и обсуждение аспектов диагностики и лечения данной патологии.Материалы и методы. Пациентка 18 лет доставлена в стационар после поражения молнией на берегу. Отмечалась потеря сознания, кратковременно отсутствовало дыхание, свидетели происшествия проводили искусственное дыхание и наружный массаж сердца. При поступлении – признаки шока на фоне инфузии допамина, кожный покров бледно-серый, холодный, следы термического повреждения по типу соприкосновения с металлом различной локализации на шее, волосистой части головы, передней поверхности грудной клетки, брюшной стенке, в паховой области, на левой стопе. Госпитализирована в ОРИТ, начат комплекс мер диагностики и интенсивной терапии. Выявлены декомпенсированный метаболический ацидоз, биохимические признаки повреждения миокарда и мышечной ткани. Назначены инфузионная терапия, анальгетики, антибиотики, блокаторы протонной помпы, антикоагулянты. На фоне проводимого лечения в первые 6 часов явления шока купированы, через 4 суток в стабильном состоянии переведена в травматологическое отделение. После перевода из ОРИТ сохраняются нарушения слуха, боль и нарушения чувствительности в левой стопе.Заключение. Необходим комплексный подход в диагностике, лечении, реабилитации пациентов с поражением атмосферным электричеством

Diffractive gauge bosons production beyond QCD factorisation

We discuss single diffractive gauge bosons ($\gamma^*,\,W^{\pm},\,Z$) production in proton-proton collisions at different (LHC and RHIC) energies within the color dipole approach. The calculations are performed for gauge bosons produced at forward rapidities. The diffractive cross section is predicted as function of fractional momentum and invariant mass of the lepton pair. We found a dramatic breakdown of the diffractive QCD factorisation caused by an interplay of hard and soft interactions. Data from the CDF experiment on diffractive production of $W$ and $Z$ are well explained in a parameter free way.Comment: 28 pages, 10 figures; a clarification of absorptive corrections has been added, typos corrected; the published versio

Self-induced and induced transparencies of two-dimensional and three- dimensional superlattices

The phenomenon of transparency in two-dimensional and three-dimensional superlattices is analyzed on the basis of the Boltzmann equation with a collision term encompassing three distinct scattering mechanisms (elastic, inelastic and electron-electron) in terms of three corresponding distinct relaxation times. On this basis, we show that electron heating in the plane perpendicular to the current direction drastically changes the conditions for the occurrence of self-induced transparency in the superlattice. In particular, it leads to an additional modulation of the current amplitudes excited by an applied biharmonic electric field with harmonic components polarized in orthogonal directions. Furthermore, we show that self-induced transparency and dynamic localization are different phenomena with different physical origins, displaced in time from each other, and, in general, they arise at different electric fields.Comment: to appear in Physical Review

Gluon Shadowing in DIS off Nuclei

Within a light-cone quantum-chromodynamics dipole formalism based on the Green function technique, we study nuclear shadowing in deep-inelastic scattering at small Bjorken xB < 0.01. Such a formalism incorporates naturally color transparency and coherence length effects. Calculations of the nuclear shadowing for the \bar{q}q Fock component of the photon are based on an exact numerical solution of the evolution equation for the Green function, using a realistic form of the dipole cross section and nuclear density function. Such an exact numerical solution is unavoidable for xB > 0.0001, when a variation of the transverse size of the \bar{q}q Fock component must be taken into account. The eikonal approximation, used so far in most other models, can be applied only at high energies, when xB < 0.0001 and the transverse size of the \bar{q}q Fock component is "frozen" during propagation through the nuclear matter. At xB < 0.01 we find quite a large contribution of gluon suppression to nuclear shadowing, as a shadowing correction for the higher Fock states containing gluons. Numerical results for nuclear shadowing are compared with the available data from the E665 and NMC collaborations. Nuclear shadowing is also predicted at very small xB corresponding to LHC kinematical range. Finally the model predictions are compared and discussed with the results obtained from other models.Comment: 29 pages including 7 figures; Fig.7 modified, some references and corresponding discussion adde

Spectroscopic studies of defects in gamma- and neutron-irradiated magnesium aluminates spinel ceramics

The spectroscopic investigations of defects in optical spinel ceramics irradiated with gamma-rays from ⁶⁰Co source and mixed neutron-gamma field in WWR reactor to neutron fluences of 1·10¹³ and 5·10¹³ n/cm² were provided. The obtained data on the dose dependence of intensity of absorption bands in the visible range allow to identify the origin of optical centers formed under irradiation. Absorption in IR range indicates on the presence in ceramics carbon-related complexes that become active after irradiation. The registered EPR signal of g = (2.0174±0.0005) and width of (46.1±1.5) G which corresponds to HO₂⁻ or O₃⁻ radicals. The dependences of the investigated centers on annealing temperature of the irradiated spinel ceramics show unusual increase in intensity of absorption and steady-state radio-luminescence in the temperature range of 200…400 °C. The role of complexes of defects including anti-site defects in formation and healing of defects in different temperature ranges are analyzed taking into account different mobility of cations and anions and specific mechanism of radio-luminescence.Проведені спектроскопічні дослідження в оптичній кераміці шпінелі, опроміненій гамма-променями джерела ⁶⁰Co та змішаним гамма-нейтронним потоком у ВВР реакторі при потоках нейтронів 1·10¹³ та 5·10¹³ нейтр./см². Одержані дані із залежності інтенсивності смуг поглинання у видимій області дозволили ідентифікувати природу оптичних центрів, створених опромінюванням. Поглинання світла в інфрачервоній області вказує на присутність у кераміці комплексів, що містять вуглець та стають оптично активними після опромінення. Зареєстрований сигнал ЕПР з g = (2.0174 ±0.0005) і шириною (46.1±1.5) Гс, що відповідає HO₂⁻ - або O₃⁻ -радикалам. Залежність досліджених центрів від температури відпалу в опроміненій кераміці шпінелі демонструє незвичайне збільшення інтенсивності поглинання та стаціонарної люмінесценції в інтервалі температур 200…400 °C. Проаналізована роль комплексів дефектів, які включають дефекти антиструктури в створенні та відпалу дефектів у різних температурних областях з урахуванням різної рухливості катіонів та аніонів, а також специфіки механізму рентегнолюмінесценції.Проведены спектроскопические исследования оптической керамики шпинели, облученной гамма-квантами источника ⁶⁰Co и смешанным гамма-нейтронным потоком в реакторе ВВР при потоках нейтронов 1·10¹³ и 5·10¹³ нейтр./см². Полученные данные из зависимости интенсивности полос поглощения в видимой области позволили определить природу оптических центров, созданных облучением. Поглощение света в инфракрасной области указывает на присутствие в керамике углеродсодержащих комплексов, которые становятся оптически активными после облучения. Зарегистрированный сигнал ЭПР с g = (2.0174 ±0.0005) и шириной (46.1±1.5) Гс, соответствующий HO₂⁻ - или O₃⁻ -радикалам. Зависимость концентраций исследованных центров от температуры отжига в облученной керамике шпинели демонстрирует необычный рост интенсивности поглощения и стационарной люминесценции в интервале температур 200…400 °C. Проанализирована роль комплексов дефектов, которые включают дефекты антиструктуры в образовании и отжиге дефектов в различных температурных областях с учетом различной подвижности катионов и анионов, а также специфики механизма рентгенолюминесценции