Genetic diversity of Sclerocarya birrea subspecies birrea populations in Burkina Faso detected by RAPDs

Sclerocarya birrea, multipurpose plant is characteristic of the Sahel-Sudanian savanna and is widespread in West Africa. Although this species has a high socio-economic importance, its genetic organization was not well characterized in Burkina Faso. In this study, the intra and interpopulation genetic diversity of S. birrea was determined by random amplified polymorphic deoxyribonucleic acid (RAPD) markers. We found a high average of intra population genetic diversity (He = 0.20) among S. birrea populations. The species populations were also characterized by their low genetic differentiation (Gst = 0.24), indicating a significant exchange of genes flow between populations. The whole population was clustered into four groups without reference of site and climatic zone. The Mantel test suggested that genetic distances between populations were not correlated to geographic distances. Our results strongly suggest that the structure and the level of this species’ genetics diversity may be due to its mode of dissemination involving ruminants.Key words: Genetic, variation, Sclerocarya birrea subspecies birrea, populations, RAPDs markers, Burkina Faso

Opportunities for TeV Laser Acceleration

A set of ballpark parameters for laser, plasma, and accelerator technologies that define for electron energies reaching as high as TeV are identified. These ballpark parameters are carved out from the fundamental scaling laws that govern laser acceleration, theoretically suggested and experimentally explored over a wide range in the recent years. In the density regime on the order of 10^{16} cm^{-3}, the appropriate laser technology, we find, matches well with that of a highly efficient high fluence LD driven Yb ceramic laser. Further, the collective acceleration technique applies to compactify the beam stoppage stage by adopting the beam-plasma wave deceleration, which contributes to significantly enhance the stopping power and energy recovery capability of the beam. Thus we find the confluence of the needed laser acceleration parameters dictated by these scaling laws and the emerging laser technology. This may herald a new technology in the ultrahigh energy frontier.Comment: 16 pages, 2 figures, 1 table, submitted to AIP Conference Proceeding

Coulomb implosion mechanism of negative ion acceleration in laser plasmas

Coulomb implosion mechanism of the negatively charged ion acceleration in laser plasmas is proposed. When a cluster target is irradiated by an intense laser pulse and the Coulomb explosion of positively charged ions occurs, the negative ions are accelerated inward. The maximum energy of negative ions is several times lower than that of positive ions. The theoretical description and Particle-in-Cell simulation of the Coulomb implosion mechanism and the evidence of the negative ion acceleration in the experiments on the high intensity laser pulse interaction with the cluster targets are presented.Comment: 4 page

Transverse Dynamics and Energy Tuning of Fast Electrons Generated in Sub-Relativistic Intensity Laser Pulse Interaction with Plasmas

The regimes of quasi-mono-energetic electron beam generation were experimentally studied in the sub-relativistic intensity laser plasma interaction. The observed electron acceleration regime is unfolded with two-dimensional-particle-in-cell simulations of laser-wakefield generation in the self-modulation regime.Comment: 10 pages, 5 figure

Lorentz-Abraham-Dirac vs Landau-Lifshitz radiation friction force in the ultrarelativistic electron interaction with electromagnetic wave (exact solutions)

When the parameters of electron - extreme power laser interaction enter the regime of dominated radiation reaction, the electron dynamics changes qualitatively. The adequate theoretical description of this regime becomes crutially important with the use of the radiation friction force either in the Lorentz-Abraham-Dirac form, which possess unphysical runaway solutions, or in the Landau-Lifshitz form, which is a perturbation valid for relatively low electromagnetic wave amplitude. The goal of the present paper is to find the limits of the Landau-Lifshitz radiation force applicability in terms of the electromagnetic wave amplitude and frequency. For this a class of the exact solutions to the nonlinear problems of charged particle motion in the time-varying electromagnetic field is used.Comment: 14 pages, 5 figure

Soft X-ray harmonic comb from relativistic electron spikes

We demonstrate a new high-order harmonic generation mechanism reaching the `water window' spectral region in experiments with multi-terawatt femtosecond lasers irradiating gas jets. A few hundred harmonic orders are resolved, giving uJ/sr pulses. Harmonics are collectively emitted by an oscillating electron spike formed at the joint of the boundaries of a cavity and bow wave created by a relativistically self-focusing laser in underdense plasma. The spike sharpness and stability are explained by catastrophe theory. The mechanism is corroborated by particle-in-cell simulations

Observation of Burst Intensification by Singularity Emitting Radiation generated from relativistic plasma with a high-intensity laser

Coherent x-rays via the Burst Intensification by Singularity Emitting Radiation (BISER) mechanism are generated from relativistic plasma in helium gas target. A broad modulation of the BISER spectrum, which is significantly wider than the harmonic order, is observed and characterized. In particular, we found that the modulation period can be as large as 41 eV

Stability improvement of a laser-accelerated electron beam and the pulse width measurement of the electron beam

Laser wakefield acceleration has the possibility to generate an ultrashort electron beam of the order of femtoseconds or less. In applications of these laser accelerated electron beams, stable and controllable electron beams are necessary. A high stability electron bunch is generated by laser wakefield acceleration with the help of a colliding laser pulse (optical injection). Stable and monoenergetic electron beams have been generated in the self-injection scheme of laser acceleration by using a Nitrogen gas jet target. The electron interaction with the laser field results in transverse oscillations of the electron beam. From the electron oscillation period dependence on the electron energy we find that the electron beam width is equal to 1.7 fs (rms).В процессе ускорения кильватерными волнами возможна генерация сверхкоротких электронных пучков фемтосекундной длительностью. Для приложений требуются электронные пучки с воспроизводимыми и котролируемыми параметрами. Оптическая инжекция, использующая сталкивающиеся лазерные импульсы, обеспечивает высокую воспроизводимость параметров пучков ускоренных электронов. Моноэнергетические пучки электронов с воспроизводимыми параметрами были получены при «самоинжекции» в кильватерную волну в экспериментах, использующих в качестве мишени струю азота. Взаимодействие электронов с излучением лазерного импульса приводит к поперечным осцилляциям электронного пучка. Анализ наблюдаемой в эксперименте зависимости периода осцилляций от энергии электронов позволяет найти длительность электронного пучка, равную 1.7 фс.В процесі прискорення кільватерними хвилями можлива генерація надкоротких електронних пучків фемтосекундної тривалості. Для додатків потрібні електронні пучки з відтворюючими і котролюючими параметрами. Оптична інжекція, що використовує зіштовхуючі лазерні імпульси, забезпечує високу відтворюваність параметрів пучків прискорених електронів. Моноенергетичні пучки електронів з відтворюваними параметрами були отримані при «самоінжекції» в кільватерну хвилю в експериментах, в яких в якості мішені використовувалася струмінь азоту. Взаємодія електронів з випромінюванням лазерного імпульсу призводить до поперечних осциляцій електронного пучка. Аналіз спостерігаючої в експерименті залежності періоду осциляцій від енергії електронів дозволяє знайти тривалість електронного пучка, яка дорівнює 1.7 фс