Low-lying resonances of Be9Lambda : Faddeev calculation with Pade-approximants

Configuration space Faddeev equations are applied to describe the Be9Lambda low-lying resonances of the ground band in the alpha+alpha+Lambda cluster model. The method of analytical continuation in coupling constant is used.Comment: 4 pages, 3 Postscript figures, Talk at the 18th International IUPAP Conference on Few-Body Problems in Physics, Aug. 21-26, 2006, Santos, Brazi

Charged plasma interaction with a surface in crossed fields

Problems of non-linear dynamics and non-stationary behaviour of charged plasma interacting with secondary emission surfaces in crossed E×B-fields are discussed from the point of view of the investigation of new approaches for microwave electronic devices. Self-organisation of flows and formation of regular space structures due to the feedback at the emitting surface is shown. The results of computer simulations of electron clouds formation due to non-linear azimuthal instability inside coaxial systems embedded inside in external magnetic field under the condition of strong non-uniform secondary self-sustaining emission are described. The existence of quasi-stationary, rotating state of charged flow has been shown under conditions of conservation of full power and full momentum of the system. It is emphasised the dominant influence of a feedback due to non-uniform secondary emission on dynamics of plasma flow modulation and on arising of a leakage current across external magnetic field.Обговорюються проблеми нелінійної динаміки і нестаціонарного поводження зарядженої плазми, взаємодіючою з повторно-емісійною поверхнею в схрещених полях, з позиції дослідження нових підходів для пристроїв мікрохвильової електроніки. Показано можливість самоорганізації потоків і формування регулярних просторових структур, обумовлена зворотним зв'язком на емітувальній поверхні. Дано опис результатів чисельного моделювання формування електронних структур у коаксіальних системах, що знаходяться в зовнішньому магнітному полі, в умовах неоднорідної самопідтримної вторинної емісії. Показано можливість існування стаціонарно обертових станів в умовах збереження повної потужності і повного моменту системи. Звертається особлива увага на домінуючий вплив зворотного зв'язку і неоднорідності вторинної емісії на динаміку модуляції потоків і виникнення струмів витоку поперек зовнішнього магнітного поля.Обсуждаются проблемы нелинейной динамики и нестационарного поведения заряженной плазмы, взаимодействующей с вторично-эмиссионной поверхностью в скрещенных полях, с позиции исследования новых подходов для устройств микроволновой электроники. Показана возможность самоорганизации потоков и формирования регулярных пространственных структур, обусловленная обратной связью на эмитирующей поверхности. Дано описание результатов численного моделирования формирования электронных структур в коаксиальных системах, находящихся во внешнем магнитном поле, в условиях неоднородной самоподдерживающейся вторичной эмиссии. Показана возможность существования стационарно вращающихся состояний в условиях сохранения полной мощности и полного момента системы. Обращается особое внимание на доминирующее влияние обратной связи и неоднородности вторичной эмиссии на динамику модуляции потоков и возникновение токов утечки поперек внешнего магнитного поля

Selforganisation and dynamics peculiarities of intense electron beams in compact crossed fields systems

The review of the results of computer simulations of electron flow self-organisation inside magnetically isolated coaxial diodes (magnetron gun) is given. Magnetron guns of usual and inverted polarities are considered

Self-sustaining secondary emission in magnetron guns, beam modulation and feedbacks

This paper reports on computer simulations of an electron cloud formation inside a smooth-bore magnetron. Preliminary results were published in [1-3]. Computer simulations have been performed using 2.5D and 3D electromagnetic PIC code KARAT [4] for the magnetron diode (MD) with parameters close to experimental [5], and with an external voltage source V0(t) connected to MD via an RL-circuit. The yield of secondary electrons from the cathode takes into account the dependence of the yield on the energy of electrons and the angle between the direction of electron velocity and the perpendicular to the cathode surface, and also the threshold of secondary emission

Three-body halos. V. Computations of continuum spectra for Borromean nuclei

We solve the coordinate space Faddeev equations in the continuum. We employ hyperspherical coordinates and provide analytical expressions allowing easy computation of the effective potentials at distances much larger than the ranges of the interactions where only s-waves in the different Jacobi coordinates couple. Realistic computations are carried out for the Borromean halo nuclei 6He (n+n+\alpha) for J\pi = 0+-, 1+-, 2+- and 11Li (n+n+9Li) for (1/2)+-, (3/2)+-, (5/2)+-. Ground state properties, strength functions, Coulomb dissociation cross sections, phase shifts, complex S-matrix poles are computed and compared to available experimental data. We find enhancements of the strength functions at low energies and a number of low-lying S-matrix poles.Comment: 35 pages, 14 figure

Intrinsic tunneling spectroscopy: A look from the inside at HTSC

Layered structure of Bi-2212 high $T_c$ superconductor (HTSC), provides a unique opportunity to probe quasiparticle density of states inside a bulk single crystal by means of intrinsic (interlayer) tunneling spectroscopy. Here I present a systematic study of intrinsic tunneling characteristics of Bi-2212 as a function of doping, temperature, magnetic field and intercalation. An improved resolution made it possible to simultaneously trace the superconducting gap (SG) and the normal state pseudo-gap (PG) in a close vicinity of $T_c$ and to analyze closing of the PG at $T^*$. The obtained doping phase diagram exhibits a critical doping point for appearance of the PG and a characteristic crossing of the SG and the PG close to the optimal doping. All this points towards coexistence of two different and competing order parameters in Bi-2212.Comment: 4 pages, 5 figures, Presentation at M2S-Rio (May 2003), Subm. to Physica C. Note: A discussion of magnetic field dependencies is adde

Maxwell Equations in Complex Form of Majorana - Oppenheimer, Solutions with Cylindric Symmetry in Riemann S_{3} and Lobachevsky H_{3} Spaces

Complex formalism of Riemann - Silberstein - Majorana - Oppenheimer in Maxwell electrodynamics is extended to the case of arbitrary pseudo-Riemannian space - time in accordance with the tetrad recipe of Tetrode - Weyl - Fock - Ivanenko. In this approach, the Maxwell equations are solved exactly on the background of static cosmological Einstein model, parameterized by special cylindrical coordinates and realized as a Riemann space of constant positive curvature. A discrete frequency spectrum for electromagnetic modes depending on the curvature radius of space and three parameters is found, and corresponding basis electromagnetic solutions have been constructed explicitly. In the case of elliptical model a part of the constructed solutions should be rejected by continuity considerations. Similar treatment is given for Maxwell equations in hyperbolic Lobachevsky model, the complete basis of electromagnetic solutions in corresponding cylindrical coordinates has been constructed as well, no quantization of frequencies of electromagnetic modes arises.Comment: 39 page

Cluster models of Lambda-Lambda-6He and Lambda-9Be hypernuclei

Configuration space Faddeev calculations are performed for the binding energy of Lambda-Lambda-6He and Lambda-9Be bound states, here considered as alpha-Lambda-Lambda and alpha-alpha-Lambda clusters respectively, in order to study the dependence of the calculated binding energy on the alpha-Lambda potential input. For Lambda-Lambda-6He, using realistic interactions, the uncertainty in extracting the Lambda-Lambda S=L=0 interaction strength does not exceed 0.1 MeV, which is a fraction of the order of magnitude derived for other theoretical uncertainties. For Lambda-9Be, the dependence of the calculated binding energy on the alpha-Lambda potential is considerably larger, of order 1 MeV. Our results for Lambda-9Be suggest that the odd-state alpha-Lambda interaction is substantially reduced with respect to the even-state component.Comment: 16 pages, including 4 figures, typos corrected, slightly revised, accepted to Nuclear Physics

Preparation of facilities for fundamental research with ultracold neutrons at PNPI

The WWR-M reactor of PNPI offers a unique opportunity to prepare a source for ultracold neutrons (UCN) in an environment of high neutron flux (about 3*10^12 n/cm^2/s) at still acceptable radiation heat release (about 4*10^-3 W/g). It can be realized within the reactor thermal column situated close to the reactor core. With its large diameter of 1 m, this channel allows to install a 15 cm thick bismuth shielding, a graphite premoderator (300 dm^3 at 20 K), and a superfluid helium converter (35 dm^3). At a temperature of 1.2 K it is possible to remove the heat release power of about 20 W. Using the 4pi flux of cold neutrons within the reactor column can bring more than a factor 100 of cold neutron flux incident on the superfluid helium with respect to the present cold neutron beam conditions at the ILL reactor. The storage lifetime for UCN in superfluid He at 1.2 K is about 30 s, which is sufficient when feeding experiments requiring a similar filling time. The calculated density of UCN with energy between 50 neV and 250 neV in an experimental volume of 40 liters is about 10^4 n/cm^3. Technical solutions for realization of the project are discussed.Comment: 10 pages, more detail

Application of the hydrosurgery system and plasmajet for thoracoscopic debridement of pleural cavity in children with fibrinothorax

Introduction. Thoracoscopy became a favored modality in pediatric pleural empyema treatment. However, the factors affecting on outcome of thoracoscopic management remain unclear. Purpose of the study Demonstration of hydrosurgery system “Versajet” and the plasma unit “Plasmajet” during thoracoscopic treatment of children with pleural complications destructive pneumonia. Materials and methods. 377 patients with a pneumonia was treated at the Speransky Children’s Hospital in Moscow for the last 1 year. 62 patients (16.45%) from 377 required drainage of the pleural cavity. 14 patients from 1.6 to 15 years of age (mean, 3.2 ± 3.8) with pleural empyema were operated -Thoracoscopic pleural cavity sanitation with hydrosurgery system (Versajet-2) Hydrosurgery system is a surgical instrument based on the impact of high-speed jet of water on necrotic and inflamed tissues, combining the advantages of acute cleansing tissue and processing them by pulsating water jet. The design of the evacuation tube and its close proximity to the liquid jet creates a local vacuum, which effectively removes fibrin and liquid contents by Bernulli effect. Informed consent was obtained from parents, and the procedure received approval from the local ethics committee. Results. Recovery and rehabilitation was uneventful in 13 cases. 1 patient with empyema of the right pleural cavity and severe organic lesion of the central nervous system was treated in our hospital by thoracoscopic adhesiolysis. However, postoperative period was complicated by recurrence of pleural empyema and cortication of right lung. Rethoracoscopy was performed six days later after initial operation - thoracoscopic debridement of pleural cavity, decortications of the right lung by hydrosurgery system with good results after surgery. Mean operative time was 90 minutes (± 15 minutes). Drainage of the pleural cavity was removed 3-4 days after surgery. The childrens were discharged from the hospital on day 10 (± 1.2 days). After application of argon plasma coagulation has been achieved complete aerostasis in 2 patients, hemostasis - in 1 patient. Ultrasound and X-rays examination 4 months after surgery confirmed the absence of inflammation in the lung parenchyma and full lung reexpantion in all patients. Conclusions. Application Hydrosurgycal system during thoracoscopy, provide effective debridement of pleural cavity, decortications of the lung without damaging the lung parenchyma and create conditions for early rehabilitation of the compromised lung