Electromagnetic transitions between giant resonances within a continuum-RPA approach

A general continuum-RPA approach is developed to describe electromagnetic transitions between giant resonances. Using a diagrammatic representation for the three-point Green's function, an expression for the transition amplitude is derived which allows one to incorporate effects of mixing of single and double giant resonances as well as to take the entire basis of particle-hole states into consideration. The radiative widths for E1 transition between the charge-exchange spin-dipole giant resonance and Gamow-Teller states are calculated for ^{90}Nb and ^{208}Bi nuclei. The importance of the mixing is stressed.Comment: 10 pages, 2 figures, uses elsart.st

Spatial distribution of atmospheric methane over Lake Baikal surface

Methane is the most important of organic substance in the atmosphere, and its concentration significantly exceeds the concentration of other organic compounds. The contribution from methane to the greenhouse effect is about 30 % of that from carbon dioxide. On the global scale, natural sources of methane are wetlands, rice fields, cattle, biomass burning, as well as gas-hydrates.The discovery of natural methane gas-hydrates sparked the increased interest in gashydrates and was followed by a series of investigations, by which enormous fuel reserves were discovered in the form of gas-hydrates stored in the bottom of the world ocean. Gas-hydrates attract a lot of scientific attention, not only because they can be used as fuel and chemical raw material, but also in the context of possible emissions of the methane into the atmosphere. Gas-hydrate crystals in Lake Baikal have been found quite recently. Lake Baikal is a convenient object for the investigation of gas hydrates and of gas vents at the lake floor. The aim of this work was to find anomalies in the methane distribution in the atmosphere over Lake Baikal surface using a high-sensitivity laser methane detector.The methane detector employs a GaInPAs diode laser as a source of radiation. The diode laser operates in the range from 6000 to 6080 cm-1 (1.645-1.666 µm), which includes rather strong absorption lines of methane. The detector was calibrated by a nitrogen-methane mixture with a methane concentration of 2.0 ppm. The detection limit (standard deviation) was 0.037 ppm, and time constant of the methane detector on the whole (with the allowance for the pump productivity and cell volume) was 99 s (spatial resolution of 450 m).The measurements of the methane content in the atmosphere over Lake Baikal were conducted by means of continuous air sampling from a height of 2-10 m above the water level from aboard R/V Vereshchagin in the periods of 10-16 August 2003 and of 16-24 June 2004. The coordinates of the measurement points were determined by the shipboard GPS system.Analysis of the data obtained in the course of the August 2003 expedition has shown that the methane concentration in near-surface air all along Lake Baikal averaged 2.001(0.16) ppm ; the standard deviation did not exceed 0.2 ppm. A distinctive and considerable (5.5 ppm) anomaly was observed near a shallow-water seep near the Selenga River inflow. Methane concentration distribution in near-surface air along the vessel’s track of 15 August 2003 showed a sharp peak that was limited in space and time.The average methane concentration in near-surface air over the South and Central Baikal Basins during the June 2004 expedition was 1.91(0.07) ppm and distinctive and considerable (more than 2.4 ppm) anomalies were observed at six areas in the Central Baikal Basin. Methane concentration distribution in near-surface air along the vessel’s tracks of 16-24 June 2004 was similar to the one obtained in 2003, with sharp peaks that were limited in space and time. Maximum air methane concentration (30 ppm) was detected near the Selenga shallow-water seep. In contrast to data obtained in August 2003 in the areas of visible methane escapes (Selenga River inflow and Babushkin village) groups of closely set methane escapes were observed. The distinctive and considerable (4 ppm) peak of the near-surface air methane concentration was observed near Mishicha, at a water depth of about 1000 m.The direct measurements of methane fluxes are very important for assessment of global fluxes of methane from water surface to the atmosphere. These measurements were carried out on vessel board for the first time. The most intensive fluxes (maximum methane flux was 2.12 E-9 kg/s m2) were observed near Babushkin village, where also maximum values of methane concentrations in near-surface water were detected. The typical magnitude of methane flux in most areas was within the limits of 1-3 E-12 kg/s m2. We also observed small inverse metha

Precision doublet of magnetic quadrupole lenses for ion beam formation

The precision doublet of magnetic quadrupole lenses is presented. The doublet yoke and poles made from a single piece of soft magnetic iron. Doublet manufacturing technology provides of alignment of the geometric axes in the lenses with an accuracy of a few microns. The doublet geometry was chosen to obtain the maximum magnetic induction at the poles for a given radius of the lens aperture as a result of numerical simulation. An experimental study of the doublet properties was carried out using a setup for field reconstruction technique for magnetic quadrupole lenses. The relative position of the physical axes of the lenses (the geometrical location of points with zero magnetic induction) and the magnitudes of the parasitic multipole field components were determined.Розглянуто прецизійний дублет магнітних квадрупольних лінз. Ярмо і полюса дублета виготовлені з цілісного шматка магнітом’якого заліза. Технологія виготовлення дублета забезпечує співвісність геометричних осей в лінзах з точністю до декількох мікрометрів. Геометрія дублета була обрана з метою отримання максимальної магнітної індукції на полюсах для заданого радіуса апертури лінзи в результаті чисельного моделювання. Експериментальне дослідження властивостей дублета проводилося на установці для відновлення поля в магнітних квадрупольних лінзах. Визначено відносне положення фізичних осей лінз (геометричне розташування точок з нульовою магнітною індукцією) і величини паразитних мультипольних компонент поля.Рассмотрен прецизионный дублет магнитных квадрупольных линз. Ярмо и полюса дублета изготовлены из цельного куска магнитомягкого железа. Технология изготовления дублета обеспечивает соосность геометрических осей в линзах с точностью до нескольких микрометров. Геометрия дублета была выбрана с целью получения максимальной магнитной индукции на полюсах для заданного радиуса апертуры линзы в результате численного моделирования. Экспериментальное исследование свойств дублета проводилось на установке для восстановления поля в магнитных квадрупольных линзах. Определены относительное положение физических осей линз (геометрическое расположение точек с нулевой магнитной индукцией) и величины паразитных мультипольных компонент поля

Vector proton beam writing system

Vector method for scanning with focused beam of megaelectronvolt-energy in proton-beam writing is described. Vector proton-beam writing method was proven experimentally to have numerous advantages over raster method. Focused beam size and shape are measured by scanning standard copper mesh for e-beam microscopy. Prospectives of hardware and software upgrade are regarded. Vector proton-beam writing technology can be used in many appli-cations, including X-ray optics, electronics prototyping, microrobotics, microfluidics, photonics and microstructure fabrication in new materials.Дано опис векторного методу сканування сфокусованим пучком мегаелектронвольтних енергій в протонно-променевій літографії. Експериментально доведено, що векторний метод протонно-променевої літографії має ряд переваг перед растровим методом. Визначення форми та розмірів сфокусованого пучка здійснюється за рахунок сканування стандартної мідної сітки для електронної мікроскопії. Розглянуті подальші шляхи вдосконалення обладнання та програмного забезпечення. Технологія векторної протонної літографії може бути використана в багатьох застосуваннях, включно з рентгенівською оптикою, прототипуванням електроніки, мікроробототехнікою, рідинними мікроструктурами (мікрофлюїдика), фотонікою і створенням мікроструктур у нових матеріалах

High resolution probe-forming system with spherical aberration correction for nuclear microprobe

A probe-forming system based on a separate orthomorphic quadruplet of magnetic quadrupole lenses with a short working distance is considered, allowing the system demagnification to be significantly increased. Three magnetic octupole lenses are used to correct spherical aberrations. The parameters of the octupole corrector are calculated using the matricant method. The focusing properties of the system are determined by means of a probe formation optimization process based on the value of the maximum reduced collimated acceptance. The calculations performed showed the feasibility of such a probe forming system for microanalysis and proton beam writing technique.Розглянуто зондоформуючу систему на базі розподіленого ортоморфного квадруплету магнітних квадрупольних лінз з малою робочою відстанню, що дозволило значно збільшити коефіцієнти зменшення. Для корекції сферичних аберацій застосовуються три магнітні октупольні лінзи. Розрахунок параметрів октупольного коректора виконується методом матрицантів. Фокусуючі властивості системи визначаються за рахунок оптимізації процесу формування зонда на основі величини максимального приведеного колімованого аксептансу. Проведені розрахунки показали, що така система може бути реалізована для застосування в методиках мікроаналізу та протонно-променевої літографії

Using of proton beam writing techniques for fabrication of micro difraction gratings

To obtain micrometric gratings with a high aspect ratio by lithographic technique, it is proposed to use a proton beam focused in a line and electromagnetic scanning in the transverse direction to irradiate the resistive material. Numerical modeling is carried out to optimize the parameters of the probe forming system for this task. The calculations were confirmed during the experimental implementation of the proposed technique. A grating from the 23.4×2060 μm lines was made.Для виробництва мікродифракційних граток з великим аспектним співвідношенням методом літографії запропоновано застосувати для опромінення фоторезисту протонний пучок, сфокусований в лінію, та електромагнітне сканування в поперечному напрямку. Проведене чисельне моделювання з оптимізації параметрів ЗФС для даної задачі. Розрахунки підтверджено при експериментальній реалізації запропонованого методу, виготовлено гратку зi смугами розмірами 23,4×2060 мкм.Для получения микродифракционных решеток с высоким аспектным соотношением методом литографии предложено использовать для облучения фоторезиста протонный пучок, сфокусированный в линию, и электромагнитное сканирование в поперечном направлении. Проведено численное моделирование по оптимизации параметров ЗФС для данной задачи. Расчеты подтверждены при экспериментальной реализации предложенного метода, получена решетка из полос размерами 23,4×2060 мкм

Non-Linear Vibrations in Nuclei

We have perfomed Time Dependant Hartree-Fock (TDHF) calculations on the non linear response of nuclei. We have shown that quadrupole (and dipole) motion produces monopole (and quadrupole) oscillations in all atomic nuclei. We have shown that these findings can be interpreted as a large coupling between one and two phonon states leading to large anharmonicities.Comment: 4 pages, 3 figure

Self-consistent approach for excitons in quantum wells

We introduce a computationally efficient approach to calculating the characteristics of excitons in quantum wells. In this approach we derive a system of self-consistent equations describing the motion of an electron-hole pair. The motion in the growth direction of the quantum well in this approach is separated from the in-plane motion, but each of them occurs in modified potentials found self-consistently. The approach is applied to shallow quantum wells, for which we obtained an analytical expression for the exciton binding energy and the ground state eigenfunction. Our results are in excellent agreement with standard variational calculations, but require greatly reduced computational effort.Comment: RevTeX4, 13 pages, 4 figures, submitted to Phys. Rev B Changed content, added references, correct typo

Организационно–методическое обеспечение занятий керлингом у студентов вуза.

Статья описывает структуру и содержание организационно–методического обеспечения занятий керлингом у студентов вуза. Рассказывается о совершенствовании содержания физического воспитания студентов в вузе. Действующая программа по физическому воспитанию студентов в вузе имеет определенный регламентированный характер. Она не позволяет мотивировать студен-тов на активные занятия физической культурой спортом. В учебных заведениях Европы культивируется различные нетрадиционные двигательные формы: софтбол, гольф, дартс, крокет, карбол, пляжный волейбол, стритбол и керлинг. В вузах России студенты не современны в спортивно–оздоровительных движениях, которые популярны в мировой практике. Данное исследование рассматривает интеграцию физического воспитания студентов России и Европы. Ключевые слова (словосочетания): керлинг, физическое воспитание студентов, структура и содержание организационно–методического обеспечения занятий. = The article describes the structure and content of the organizational–methodical provision of training curling students of university. Improving the content of physical education of students in the university has been discussed. The operating program has the certain regulated character in physical education of students. It does not allow motivating students to the active exercises and sports. The European universities cultivate different non–conventional motive forms like softball, golf, darts, croquet, carbol, beach volleyball, street ball and curling. Students of universities of Russia don’t use modern sports movement that are popular in the world. The present research regards the integration of physical education students in Russia and Europe.Key words (expressions): curling, physical education of students, the structure and content of the or-ganizationally–methodical provision of training

Клиническое исследование отечественного фибринселективного тромболитического препарата Фортелизин® (III фаза)

The clinical trial of fibrinselective thrombolytic agent Fortelyzin® (III phase) showed the comparative efficacy and safety with Actilyse® in patients with acute myocardial infarction and obtained data permitted to recommend it for clinical usage.Проведенное исследование лекарственного препарата Фортелизин®, вводимого болюсно и болюсно-инфузионно у больных с острым инфарктом миокарда с подъемом сегмента ST, показало сравнимую с Актилизе® эффективность и безопасность исследуемого препарата и позволило рекомендовать его для медицинского применения