Energy Technology Data Exchange (ETDEWEB)

Abstract not provided

International Nuclear Information System (INIS)

Elise is a heavy ion induction linear accelerator that will demonstrate beam manipulations required in a driver for inertial fusion energy. With a line charge density similar to that of heavy ion drivers, Elise will accelerate a #>=# 1 gs beam pulse of K"+ ions from an initial energy of 2 MeV to a final energy #>=# 5 MeV. In the present design, the Elise electrostatic quadrupoles (ESQ) will have a 2.33 cm radius aperture operating at #+-#59 kV. The half-lattice periods range from 21 cm to 31 cm. The entire machine will be approximately 30 m long, half of that is the induction accelerator and the remaining half is the injector (including the Marx generator) and the matching section. Elise will be built in a way that allows future expansion into the full ILSE configuration, therefore it will have an array of four ESQ focusing channels capable of transporting up to a total of 3.2 ...

CERN Document Server

Background information on the high energy physics program and the proposed Stanford linear electron accelerator project

Energy Technology Data Exchange (ETDEWEB)

A general model for wakefield-generated instabilities in linear accelerators, originally developed for cumulative beam breakup [1], is applied to the resistive wall instability. The general solution for various bunch charge distributions and application to various accelerator configurations are presented.

International Nuclear Information System (INIS)

The linearized collective Schroedinger equation for nuclear quadrupole surface vibrations incorporates a new spin degree of freeedom with a spin value of 3/2. We use this equation to describe the low energy spectrum of certain even-odd Ir nuclei which have a spin 3/2 in their ground state. For that purpose we explicitly introduce collective spin-dependent potentials which simulate the interaction of the valence nucleon with the core. The linearized Schroedinger equation is transformed into an effective Schroedinger equation with collective spin-dependent potentials. Already collective spin-orbit couplings of SO(3) and SO(5) type are sufficient to reproduce the lowest excited states of even-odd Ir nuclei. (orig.).

Energy Technology Data Exchange (ETDEWEB)

The paper outlines the basic problems concerning creation of electron-positron linear colliders, as well as their present-day status. More details on the question can be found in the proceedings of recent workshops on linear colliders contained in the References. ((orig.)).

International Nuclear Information System (INIS)

The Schroedinger equation for nuclear quadruple surface vibrations is linearized with the consequence that a new spin degree of freedom appears in the wave function of the linearized equation. This spin is called collective spin and has a value of 3/2. The linearized Schroedinger equation for quadrupole vibrations is used for the description of certain collective aspects of even-odd "1"8"7","1"8"9","1"9"1Ir nuclei which have a spin 3/2 in their ground state. As a potential we use the #gamma#-soft collective potential of the neighboring even-even nuclei, which is inserted into the linearized Schroedinger equation via a scalar coupling. This leads to a collective spin-dependent fine structure splitting of the energy levels governed by a collective SO(5) spin-orbit coupling and a correction to the kinetic energy. Further, we consider explicitly spin-dependent potentials which ...

Science.gov (United States)

Linearly polarized laser radiation accelerates electrons to very high velocities and these electron form a sheath layer on the rear side of thin targets where preferentially protons are accelerated. When mass-limited targets are used, the lateral transport of the absorbed laser energy is reduced and the accelerating field is enhanced. For targets consisting of two ion species, heavier ions facilitate formation of quasi-monoenergetic bunch of lighter ions. For circularly polarized light, fast electron production is suppressed by the absence of the oscillatory component of the ponderomotive force. Ions are accelerated on the front side by the separation field and very thin foil can be accelerated as one massive quasi-neutral block. As all ion species acquire the same velocity, this acceleration mechanism is preferred for heavier ions.

CERN Multimedia

"American dominance in the study and development of high-energy particle physics may be seriously compromised, according to a report issued by the National Academy of Sciences, unless efforts are made to ensure that the next high-energy particle accelerator - the International Linear Collider (ILC) - will be constructed in the U.S.

Science.gov (United States)

An almost linear optimization problem of importance in vibration isolation has been identified and algorithms were developed to minimize the forced vibrational response of structural systems. The constraints can be either displacements of accelerations. T...

British Library Electronic Table of Contents (United Kingdom)

In Korea, the Proton Engineering Frontier Project (PEFP) is building a proton linear accelerator facility with energy up to 100MeV and a beam current of 20mA. In this study, a radiation field after shutdown in the accelerator facility of the PEFP was evaluated for the purpose of the radiation shielding by using MCNPX code. A facility modeling was performed for the accelerator tunnel building, accelerator chain, target rooms and beam experiment hall. And radiation source terms were evaluated in the facility. With this facility, model and radiation source terms, the concentration of 41Ar was evaluated and the cooling time satisfying regulation in Korea was calculated.

International Nuclear Information System (INIS)

The applicability of Broyden's second method for accelerating the convergence of self-consistent electronic-structure calculations based on the linearized augmented-plane-wave method is discussed in terms of a W(001) surface calculation. It is found that its use results in a significant improvement in the convergence of the calculation, and based on this it is concluded that its use should increase the size of the systems for which such calculations are feasible.

Energy Technology Data Exchange (ETDEWEB)

The requirements for transporting high-current, negative-ion beams are presented with particular emphasis on applications involving negative-hydrogen-ion beams. In addition to the usual matching and steering problems, particular attention must be paid to beam emittance growth in the transport system. Depending on the application, a number of approaches have been developed using both magnetic and electric lenses. I discuss the design considerations for transporting and matching these beams to radiofrequency quadrupole accelerators, and present a survey of the various types of beamlines now used for negative-ion beams.

Energy Technology Data Exchange (ETDEWEB)

The requirements for transporting high-current, negative-ion beams are presented with particular emphasis on applications involving negative-hydrogen-ion beams. In addition to the usual matching and steering problems, particular attention must be paid to beam emittance growth in the transport system. Depending on the application, a number of approaches have been developed using both magnetic and electric lenses. I discuss the design considerations for transporting and matching these beams to radiofrequency quadrupole accelerators, and present a survey of the various types of beamlines now used for negative-ion beams.

British Library Electronic Table of Contents (United Kingdom)

We describe a method for the analysis of multi-site phosphorylation in serine/threonine (Ser/Thr)-rich protein sequences. Site-specific mutagenesis was used to introduce tryptic cleavage sites in the serine glutamine/threonine glutamine cluster domain (SCD) of the human checkpoint protein kinase (Chk2). The mutant proteins were shown to autophosphorylate on residues that are inducibly phosphorylated when mammalian cells are exposed to ionizing radiation (serine 33/35, serine 516, threonine 68 and threonine 432). Five Ser/Thr clusters within the SCD were flanked by arginine or lysine residues to produce tryptic peptides for nanospray liquid chromatography (nanoLC)/linear quadrupole ion trap Fourier transform ion cyclotron resonance mass spectrometry. Phosphorylation sites were assigned usin...

Energy Technology Data Exchange (ETDEWEB)

The SciDAC2 accelerator project at SLAC aims to simulate an entire three-cryomodule radio frequency (RF) unit of the International Linear Collider (ILC) main Linac. Petascale computing resources supported by advances in Applied Mathematics (AM) and Computer Science (CS) and INCITE Program are essential to enable such very large-scale electromagnetic accelerator simulations required by the ILC Global Design Effort. This poster presents the recent advances and achievements in the areas of CS/AM through collaborations.

Science.gov (United States)

We discuss elastic electron-deuteron (ed) scattering beyond the Born approximation. The reaction amplitude contains six generalized form factors, but only three linearly independent combinations of them (generalized charge, quadrupole, and magnetic form factors) contribute to the reaction cross section in second-order perturbation theory. We examine the two-photon exchange and find that it includes two types of diagrams, where two virtual photons are interacting with the same nucleon and where the photons are interacting with different nucleons. It is shown that the two-photon-exchange amplitude is strongly connected with the deuteron wave function at short distances.

Energy Technology Data Exchange (ETDEWEB)

The superconducting magnets and associated cryogenic components in A-sector represent the initial phase of installation of the Fermilab superconducting accelerator, designed to accelerate proton beams to energies of 1 TeV. Installation of the magnets, comprising one-eighth of the ring, was completed in December, 1981. Cooldown and power tests took place in the first half of 1982, concurrent with main ring use for 400 GeV high energy physics. The tests described in this paper involved 151 cryogenic components in the tunnel: 94 dipoles, 24 quadrupoles, 25 spool pieces, 3 feed cans, 4 turn-around boxes and 1 bypass. Refrigeration was supplied by three satellite refrigerators, the Central Helium Liquefier, and two compressor buildings. The magnets were powered by a single power supply.

Energy Technology Data Exchange (ETDEWEB)

A linear induction accelerator that produces a beam of energetic heavy ions (T -- 10 GeV, A -- 200 amu) is a prime candidate as a driver for an inertial fusion power plant. Some early perceptions were that heavy-ion drive fusion would not be cost-competitive with other power sources because of the high cost of the accelerators. However, improved understanding of the physics of heavy-ion transport and acceleration (supported by experimental results), combined with advances in accelerator technology, have resulted in accelerator design costs -- 50% of previous estimates. As a result, heavy-ion drive fusion power plants are now projected to be cost-competitive with other conceptual fusion power plants. A brief formulation of transport and acceleration physics is presented here, along with a description of the induction Linac cost optimization ...

International Nuclear Information System (INIS)

Initial design parameters and early operational results of a 50 MeV high brightness electron linear accelerator are described. The system utilizes a radio frequency electron gun operating at a frequency of 2.856 GHz and a nominal output energy of 4.5 MeV followed by two, 2#pi#/3 mode, disc loaded, traveling wave accelerating sections. The gun cathode is photo excited with short (6 psec) laser pulses giving design peak currents of a few hundred amperes. The system will be utilized to carry out infra-red FEL studies and investigation of new high gradient accelerating structures.

Energy Technology Data Exchange (ETDEWEB)

A dielectric-wall linear accelerator is improved by a high-voltage, fast rise-time switch that includes a pair of electrodes between which are laminated alternating layers of isolated conductors and insulators. A high voltage is placed between the electrodes sufficient to stress the voltage breakdown of the insulator on command. A light trigger, such as a laser, is focused along at least one line along the edge surface of the laminated alternating layers of isolated conductors and insulators extending between the electrodes. The laser is energized to initiate a surface breakdown by a fluence of photons, thus causing the electrical switch to close very promptly. Such insulators and lasers are incorporated in a dielectric wall linear accelerator with Blumlein modules, and phasing is controlled by adjusting the length of fiber optic cables that carry the laser light to the insulator surface. 12 figs.

International Nuclear Information System (INIS)

The automatic real-time system operating at the LU-10 linac and providing measurements of the parameters such as the beam current (average and pulse values), the electron energy, the linear density distribution of beam current, and also the conveyor speed is described in the paper.

British Library Electronic Table of Contents (United Kingdom)

We report acceleration of electrons moving in free space near an active Nd:YAG slab. The power of a non-relativistic beam of electrons has increased by more than 30% when the medium was excited. It is demonstrated experimentally that the energy gained by the electrons is linearly proportional to the energy stored in the medium. Moreover, the energy gain traces closely the population inversion inferred by monitoring the spontaneous radiation.

International Nuclear Information System (INIS)

Present-day requirements for radiotherapy equipment are considered. The recently developed linacs of LUE-5, LUE-25, LUE-15MM models, as well as a newly designed unified series of medical linacs of LUER-5M, LUER-20M, LUER-40M models are described in brief. The main scientific and technical problems that were solved during their construction, namely, development of accelerating structures, a radiation head, dosimetry equipment, a programming unit, a magnetic mirror etc. are described.

Science.gov (United States)

Investigations have been conducted to determine the feasibility of using collisional cooling for reducing the energy spreads and, consequently, the emittances of negative-ion beams. We have designed a gas-filled RF-quadrupole ion cooler equipped with provisions for retarding energetic negative ion beams to energies below thresholds for electron detachment at injection and for re-acceleration to high energies after the cooling process. The device has been used to cool O{sup -} and F{sup -} ion beams with initial energy spreads, {Delta}E > 10 eV to final energy spreads, {Delta}E {approx} 2 eV FWHM. Overall transmission efficiencies of {approx}14% for F{sup -} beams have been obtained. Experimental results show that electron detachment is the major loss mechanism for negative ions.

CERN Document Server

A quantitative description is presented of the non-linear current-voltage response in superconducting niobium cavities for accelerator application. It is based on a fit for a large sample of data from cavity tests of different kind. Trial functions for the surface resistance describing this non-linear relation are established by a least square data fit. Those trial functions yielding the best fit are quantitatively explained by basic physics.

British Library Electronic Table of Contents (United Kingdom)

An Otto cycle engine with internal and external irreversibilities of friction and heat leakage, in which the heat transfer between the working fluid and the environment obeys linear phenomenological heat transfer law [q ?? ?(T ?1)], is studied in this paper. The optimal piston motion trajectory for maximizing the work output per cycle is derived for the fixed total cycle time and fuel consumed per cycle. Optimal control theory is applied to determine the optimal piston trajectories for the cases of with and without piston acceleration constraint on each stroke and the optimal distribution of the total cycle time among the strokes. The optimal piston motion with acceleration constraint for each stroke consists of three segments, including initial maximum acceleration and final maximum decel...

Energy Technology Data Exchange (ETDEWEB)

The purpose of this paper is to present a summary of new methods, employing Lie algebraic tools, for characterizing beam dynamics in charged-particle optical systems. These methods are applicable to accelerator design, charged-particle beam transport, electron microscopes, and also light optics. The new methods represent the action of each separate element of a compound optical system, including all departures from paraxial optics, by a certain operator. The operators for the various elements can then be concatenated, following well-defined rules, to obtain a resultant operator that characterizes the entire system. This paper deals mostly with accelerator design and charged-particle beam transport. The application of Lie algebraic methods to light optics and electron microscopes is described elsewhere (1, see also 44). To keep its scope within reasonable bounds, they restrict their treatment of accelerator design and ...

CERN Document Server

The design of a small injection linac for a compact medical synchrotron is discussed. The linac design is based on interdigital H-type (IH) drift-tube structure with alternative phase focusing (APhF). A high acceleration rate and an absence of magnetic lenses inside drift-tubes reduce the cost and length of APhF-IH linac in comparison with HIMAC linac based on Alvarez structure with magnet quadrupoles inside drift-tubes. To reduce effects of emittance growth, the RFQ structure is used in front of the APhF linac. In such linac layout, the current transmission of a carbon beam can reach up to 90-100%. In this report, the basic parameters of whole linac are presented, while the design of APhF structure is considered in details. Two reference designs of 4 MeV/u 200 MHz APhF linacs with different voltage distributions along the whole tank have been generated and analyzed numerically. For the first design, a constant voltage distribution along the ...

Energy Technology Data Exchange (ETDEWEB)

Particle physics is driven by five great topics. Neutrino oscillations and masses are now at the fore. The standard model with extensions to supersymmetry and a Higgs to generate mass explains much of the field. The origins of CP violation are not understood. The possibility of extra dimensions has raised tantalizing new questions. A fifth topic lurking in the background is the possibility of something totally different. Many of the questions raised by these topics require powerful new accelerators. It is not an overstatement to say that for some of the issues, the accelerator is almost the experiment. Indeed some of the questions require machines beyond our present capability. As this volume attests, there are parts of the particle physics program that have been significantly advanced without the use of accelerators such as the subject of neutrino oscillations and many aspects of the particle-cosmology interface. At this ...

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

CERN Document Server

We provide a both qualitative and quantitative comparison among different approaches aimed to solve the problem of non-linear diffusive acceleration of particles at shocks. In particular, we show that state-of-the-art models (numerical, Monte Carlo and semi-analytical), even if based on different physical assumptions and implementations, for typical environmental parameters lead to very consistent results in terms of shock hydrodynamics, cosmic ray spectrum and also escaping flux spectrum and anisotropy. Strong points and limits of each approach are also discussed, as a function of the problem one wants to study.

Energy Technology Data Exchange (ETDEWEB)

Interesting developments in linear accelerators have been attained over the past 45 years. The status of linear accelerators and future possibilities are described in context of demanding applications and technology maturity. Features of industrial or `factory`-type applications are high availability, economic operations, low investment cost and ease of running a facility. All features have been demonstrated in one manner or another at large operating facilities for the research community; within a different context that has been argued in the past to be not as demanding as for `factory` installation. In addition, comments are made relative to intense beam power levels and choices that can be made for power levels below 10 MW, on the assumption that a cw beam is required. 1 fig., 1 tab.

Energy Technology Data Exchange (ETDEWEB)

The Large Hadron Collider (LHC), under construction at CERN, uses superconducting magnets operating at a temperature of 1.9 K to guide the circulating particles. A specific feature of the main magnets (dipoles and quadrupoles) is the two-in-one design with two magnetic channels in one common retaining structure. Indeed, the accelerator is made of two rings, mechanically linked, that have to be simultaneously aligned during the installation in the already existing LEP tunnel. The assembly tolerances of the LHC main magnets have been reconsidered to take into account the tight constraints on geometry. The dipoles are bent to follow closely the curvature of the circulating particles and to make a larger mechanical aperture available for the circulating particles. In order to minimise the geometrical errors the dipole assembly procedure is assisted by high precision survey measurements based on laser trackers. By this we hope to reduce to {+-} 1 mm ...

Energy Technology Data Exchange (ETDEWEB)

Studies have been conducted to determine the feasibility of using collisional cooling for reducing emittances and energy spreads in negative-ion beams to levels commensurate with effective isobaric purification with conventional high-resolution electromagnetic isobar separators as required for use at the Holifield Radioactive Ion Beam Facility (HRIBF). We have designed a gas-filled radio frequency quadrupole ion cooler equipped with provisions for retarding energetic negative-ion beams to energies below thresholds for electron detachment at injection and for re-acceleration to initial energies after the cooling process. The device has been used to cool several ion beams with initial energy spreads, {delta}E>10 eV to final energy spreads, {delta}E{approx}2 eV FWHM, including O{sup -} and F{sup -}. Overall transmission efficiencies of {approx}14% for F{sup -} beams have been obtained. Experimental results show that electron detachment is ...

International Nuclear Information System (INIS)

The project on the free electron laser (FEL) of continuous action of the IR-range with the average power of 100 kW for conducting photochemical studies is described. The electron energy recovery by means of a linear accelerator-recuperator (AR) is applied in the FEL. The FEL and AR basic parameters are presented. It is supposed that the above project will be accomplished in two stages: the first order FEL-AR stage and the full-scale FEL-AR one. The possibilities of applying these facilities are indicated

Energy Technology Data Exchange (ETDEWEB)

This paper describes a simple analysis procedure that transforms a set of beamline orbit data into a set of harmonic orbits of first, second, and third order or higher. Each harmonic orbit can be studied individually to identify errors of the specific order with minimum interference from other orders. Effectively these are orbits caused by kicks, due to harmonic errors, propagated through linear lattice. Examples from accelerator study will be presented. The application and inherent limitations of this analysis procedure are discussed.

Energy Technology Data Exchange (ETDEWEB)

The authors present design methodology and initial experimental results for a high power microwave switch. The switch is designed for application to the pulse compression system associated with the Next Linear Collider Test Accelerator (NLCTA). The switch is based on the excitation of a plasma layer within a silicon wafer by either a laser or an electron beam. They investigate problems associated with high power operation of such a switch. They explore solutions to the problems of thermal runaway, avalanche breakdown, photo-emission, and secondary emission.

Science.gov (United States)

This report presents highlights of activities in the Acceleartor Technology (AT) Division from April through December 1978. The report is divided into 10 sections to cover work done by the four groups that make up AT Division (AT-1, AT-2, AT-3, and AT-4). Section I is a brief summary of the whole report. Sections II through VI describe work done by At-1, the Linac Technology Group. Subjects covered are the Pion Generation for Medical Irradiation Program, the Electronuclear Fuel-Producing Accelerator Program, the Gyrocon rf Amplifier Program, the Electron Linear Accelerator Program, and the Free Electron Laser Program. Section VII covers the Linear Accelerator Beam Dynamics development, and Sec. VIII deals with work with the H/sup -/ Ion Source. Most of the work in Secs. VII and VIII was done by AT-2, the Special Projects Group, although work on factors influencing emittance growth ...

Energy Technology Data Exchange (ETDEWEB)

The Two-Beam Accelerator (TBA) consists of a long high-gradient accelerator structure (HGS) adjacent to an equal-length Free Electron Laser (FEL). In the FEL, a beam propagates through a long series of undulators. At regular intervals, waveguides couple microwave power out of the FEL into the HGS. To replenish energy given up by the FEL beam to the microwave field induction accelerator units are placed periodically along the length or the FEL. In this manner it is expected to achieve gradients of more than 250 MV/m and thus have serious option for a 1 TeV /times/ 1 TeV linear collider. The state of present theoretical understanding of the TBA is presented with particular emphasis upon operation of the ''steady-state'' FEL, phase and amplitude control of the rf wave, and suppression of sideband instabilities. Experimental work has focused upon the development of a ...

Energy Technology Data Exchange (ETDEWEB)

A calculation is presented of spontaneous radiation emitted by an electron beam passing through a continuously rotating quadrupole magnetic undulator. It is shown that radiation spectrum emitted in forward direction of beam propagation has four peaks, corresponding to four betatron frequencies. Utilizing the Madey theorem, a stimulated emission is calculated and presented as gain versus frequency curves, for different values of the quadrupole magnetic field. A free-electron laser operating at two or three radiation frequencies with a quadrupole magnetic wiggler is suggested.

International Nuclear Information System (INIS)

... excitation experimental data gamma radiation mev range 01-10 parity

Energy Technology Data Exchange (ETDEWEB)

The Linac Coherent Light Source (LCLS) is a SASE x-ray Free-Electron Laser (FEL) based on the final kilometer of the Stanford Linear Accelerator. Such an FEL requires a high energy, high brightness electron beam to drive the FEL instability to saturation. When fed by an RF-photocathode gun, and modified to include two bunch compressor chicanes, the SLAC linac will provide such a high quality beam at 14 GeV and 1-{micro}m normalized emittance. In this paper, we report on recent linac studies, including beam stability and tolerances, longitudinal and transverse feedback systems, conventional and time-resolved diagnostics, and beam collimation systems. Construction and installation of the injector through first bunch compressor will be completed by December 2006, and electron commissioning is scheduled to begin in January of 2007.

Energy Technology Data Exchange (ETDEWEB)

The authors report experimental results on a high gradient 17 GHz RF photocathode gun. The photocathode RF gun is a novel electron beam source intended to meet the requirements set by future high-energy linear colliders and next generation free electron lasers. A coupled pair of pillbox TM{sub 010}-like resonators is excited by sidewall coupled microwaves at 17 GHz. A picosecond ultraviolet laser pulse illuminates one wall of the structure at the axis of symmetry. Electrons are released by the photoelectric effect and are accelerated by the electric field of the microwaves in the cavity. The high frequency of operation raises the RF breakdown limit allowing strong electric fields to be used. In turn, the intense fields result in rapid acceleration of the electrons to relativistic speeds and reduced space charge induced emittance growth.

Energy Technology Data Exchange (ETDEWEB)

The construction and the development of a UV free electron laser have been started under the cooperation of Nihon U, KEK, PNC, ETL and Tohaku U. The project requires a 100MeV S-band electron linear accelerator to expand the oscillation of FEL using fundamental mode to the UV region. The injection system consists of a thermionic RF-gun with a LaB cathode and an {alpha} magnet for magnetic bunching. We are studying to reduce the back-bombardment electrons to realize the macropulse length of 20{mu}sec. Electron beams, up to the energy of 100MeV, are injected into the optical oscillators. Changing the accelerating energy and/or undulator parameters, this system will cover the range from infrared to ultraviolet for the applications in various fields.

Energy Technology Data Exchange (ETDEWEB)

Recent studies in elementary particle physics have made the need for an e{sup +}e{sup -} linear collider able to reach energies of 500 GeV and above with high luminosity more compelling than ever [1]. Observations and measurements completed in the last five years at the SLC (SLAC), LEP (CERN), and the Tevatron (FNAL) can be explained only by the existence of at least one particle or interaction that has not yet been directly observed in experiment. The Higgs boson of the Standard Model could be that particle. The data point strongly to a mass for the Higgs boson that is just beyond the reach of existing colliders. This brings great urgency and excitement to the potential for discovery at the upgraded Tevatron early in this decade, and almost assures that later experiments at the LHC will find new physics. But the next generation of experiments to be mounted by the world-wide particle physics community must not only find this new physics, they must find out what it ...

International Nuclear Information System (INIS)

We present the design, analysis, and results of the high brightness electron beam experiments currently under investigation at Sandia National Laboratories. The anticipated beam parameters are the following: energy 12 MeV, current 35 endash 40 kA, rms radius 0.5 mm, and pulse duration 40 ns full width at half-maximum. The accelerator is SABRE, a pulsed linear inductive voltage adder modified to higher impedance, and the electron source is a magnetically immersed foilless electron diode. 20 endash 30 T solenoidal magnets are required to insulate the diode and contain the beam to its extremely small-sized (1 mm) envelope. These experiments are designed to push the technology to produce the highest possible electron current in a submillimeter radius beam. Design, numerical simulations, and experimental results are presented. copyright 1997 American Institute of Physics.

CERN Document Server

Homogeneity for highly asymmetric fields has been studied for a Siemens PRIMUS linear accelerator. The flattening filter has a radius smaller than the primary collimator one, creating inhomogeneities that affect large fields in areas far from the collimator axis, and asymmetric fields with large offset. Profiles and absolute dose have been measured in fields with two jaws at maximal position (20 cm) and the other two at maximal overtravel (10 cm.), corresponding to 10 x 10 fields with extreme offset. Profiles have a remarkable gradient decreasing towards the beam edge, making these fields unsuitable for treatments. Results show that the design of the primary collimator and flattening filter assembly has direct consequences in homogeneity. This can have clinical consequences for treatments involving fields that include these inhomogeneous areas. Comparisons with the treatment planning system (Philips Pinnacle) calculations, that computes under ...

Energy Technology Data Exchange (ETDEWEB)

During this reporting period, the work supported under DOE Grant No. FG02-87ER40326.A003 has resulted in one publication, two papers submitted to Phys. Rev. C for publication, and one paper presented at a professional meeting. During this period, modifications were made to the interactive R-Matrix fitting computer program DSIG to include the total radiation widths in the R-Matrix calculation of the cross section. The R-Matrix analyses of n+{sup 90}Zr and n+{sup 208}Pn have already begun.

Energy Technology Data Exchange (ETDEWEB)

The Linac Coherent Light Source (LCLS) is a SASE x-ray Free-Electron Laser (FEL) based on the final kilometer of the Stanford Linear Accelerator. One of the most critical diagnostic devices is the bunch length monitor (BLM), which is to be installed right after each compressor utilizing coherent radiation from the last bending magnet. We describe the components and the optical layout of such a BLM. Based on the setup geometry, we discuss some issues about the coherent radiation signal.

International Nuclear Information System (INIS)

PEFP(Proton Engineering Frontier Project) is developing beamlines for various application fields by using the high current 100MeV proton linear accelerator. Beamlines were characterized and categorized by the beam energy, average currents, and irradiation conditions. Among these beamlines the TR104 is designed for the basic science and the research of the aerospace. Before the construction and installation of beamlines, we try to practice and prepare the detail process of installation by the precedent study of TR104 beamline in KAERI site. By this work installation process was checked and confirmed for the same condition of the PEFP site

International Nuclear Information System (INIS)

The Anisotropic Analytical Algorithm (AAA) is a new pencil beam convolution/superposition algorithm proposed by Varian for photon dose calculations. The configuration of AAA depends on linear accelerator design and specifications. The purpose of this study was to investigate the accuracy of AAA for an Elekta SL25 linear accelerator for small fields and intensity modulated radiation therapy (IMRT) treatments in inhomogeneous media. The accuracy of AAA was evaluated in two studies. First, AAA was compared both with Monte Carlo (MC) and the measurements in an inhomogeneous phantom simulating lung equivalent tissues and bone ribs. The algorithm was tested under lateral electronic disequilibrium conditions, using small fields (2x2 cm"2). Good agreement was generally achieved for depth dose and profiles, with deviations generally below 3% in lung inhomogeneities and below 5% at interfaces. However, the ...

International Nuclear Information System (INIS)

The present report addresses several aspects of the free electron laser (FEL) and accelerator, including their features, potentials, mechanisms, beams emitted from undulator, FEL produced by helical mangnetic field, major problems with FEL, etc. In FEL, relativistic electron beams interact with an electromagnetic field with periodically changing intensity to produce coherent electromagnetic waves with variable wavelength. The capability of varying its wavelength represents the greatest advantage over conventional lasers. Any periodic magnetic field can serve as a wiggler. A wiggler can be used both in an amplifier and oscillator. A periodic magnetic field used may be either of a parallel type or of a helical type. The polarization of emitted beams depends on the shape of the magnet regardless of whether its field is parallel or helical. An equation is derived in the report which expresses the wavelength of an electromagnetic wave produced by an undulator. An ...

CERN Document Server

We propose an innovative linear accelerating structure, particularly suited for hadrontherapy applications. Its two main features are compactness and good power efficiency at low beam velocities: the first is achieved through a high working frequency and a consequent high accelerating gradient, the second is obtained by coupling several H-mode cavities together. The structure is called CLUSTER, which stands for "Coupled-cavity Linac USing Transverse Electric Radial field". In order to compare the performance of this structure with other hadrontherapy linac designs involving high frequencies, a conceptual study has been performed for an operating frequency of 3 GHz. Moreover a proof of principle has been obtained through RF measurements on a prototype operating at 1 GHz. An accelerator complex using a CLUSTER linac is also considered for protontherapy purposes. The whole complex is called cyclinac and is ...

International Nuclear Information System (INIS)

The effects of extended source-to-surface distance (SSD) on the electron beam dose profiles were evaluated for various electron beam energies - 6, 9, 12, 15 and 20 MeV - and the accuracy of various output correction methods was analysed on a Mitsubishi linear accelerator using a radiation field analyser (RFA). The dose fall-off region of the central axis depth-dose curves was nearly independent for SSDs up to 120 cm where as in the build-up region, a marginal reduction of surface dose was observed, particularly for lower energies and for smaller field sizes. Effective SSDs and virtual source distances were evaluated for field sizes ranging from 5x5 to 15x15 cm"2 for various energies. Curve fitting was done with the measured outputs with various equations and coefficients were evaluated. The accuracy of the derived output correction factors by effective SSD, virtual source distance and curve-fit methods was assessed by evaluating correlation ...

CERN Document Server

In the CLIC main linac it is very important to minimise the trajectory excursion and consequently the emittance dilution in order to obtain the required luminosity. Several algorithms have been proposed and lately the ballistic method has proved to be very effective. The trajectory method described in this Note retains the main advantages of the latter while adding some interesting features. It is based on the separation of the unknown variables like the quadrupole misalignments, the offset and slope of the injection straight line and the misalignments of the beam position monitors (BPM). This is achieved by referring the trajectory relatively to the injection line and not to the average pre-alignment line and by using two trajectories each corresponding to slightly different quadrupole strengths. A reference straight line is then derived onto which the beam is bent by a kick obtained by moving the first quadrupole. The ...

Energy Technology Data Exchange (ETDEWEB)

The MTX explored the plasma heating effects of 140 GHz microwaves from both Gyrotrons and from the IMP FEL wiggler. The Gyrotron was long pulse length (0.5 seconds maximum) and the FEL produced short-pulse length, high-peak power, single and burst modes of 140 GHZ microwaves. Full-power operations of the IMP FEL wiggler were commenced in April of 1992 and continued into October of 1992. The Experimental Test Accelerator H (ETA-II) provided a 50-nanosecond, 6-MeV, 2--3 kAmp electron beam that was introduced co-linear into the IMP FEL with a 140 GHz Gyrotron master oscillator (MO). The FEL was able to amplify the MO signal from approximately 7 kW to peaks consistently in the range of 1--2 GW. This microwave pulse was transmitted into the MTX and allowed the exploration of the linear and non-linear effects of short pulse, intense power in the MTX plasma. Single pulses were used to explore and gain ...

Energy Technology Data Exchange (ETDEWEB)

The results that can be expected by e{gamma} and {gamma}{gamma} colliders in future are summarized. e{gamma} and {gamma}{gamma} colliders have many fine possibilities, and are the economical selection for utilizing future e{sup +}e{sup -} colliders more effectively. e{gamma} and {gamma}{gamma} colliders were proposed by former USSR researchers at the beginning of 1980s, but recently, the prospect of realizing future e{sup +}e{sup -} collision type linear accelerator projects has become high, they have become to be considered seriously as the option of remodeling them. The high energy photon beam of e{gamma} and {gamma}{gamma} colliders is obtained by causing Compton reverse scattering, irradiating laser beam to the electron beam of e{sup +}e{sup -} accelerators. The production of {gamma}-beam is explained. As for the physics noteworthy in e{gamma} colliders, abnormal gauge coupling, the formation of Higgs particles, excited ...

Energy Technology Data Exchange (ETDEWEB)

Short communication.

International Nuclear Information System (INIS)

Short communication.

Energy Technology Data Exchange (ETDEWEB)

The Fermilab Steering Group has developed a plan to keep U.S. accelerator-based particle physics on the pathway to discovery, both at the Terascale with the LHC and the ILC and in the domain of neutrinos and precision physics with a high-intensity accelerator. The plan puts discovering Terascale physics with the LHC and the ILC as Fermilab's highest priority. While supporting ILC development, the plan creates opportunities for exciting science at the intensity frontier. If the ILC remains near the Global Design Effort's technically driven timeline, Fermilab would continue neutrino science with the NOVA experiment, using the NuMI (Neutrinos at the Main Injector) proton plan, scheduled to begin operating in 2011. If ILC construction must wait somewhat longer, Fermilab's plan proposes SNuMI, an upgrade of NuMI to create a more powerful neutrino beam. If the ILC start is postponed significantly, a central feature of the ...

International Nuclear Information System (INIS)

A new foilless diode with a non-magnetically immersed cathode was recently designed and built for the Sandia Recirculating Linear Accelerator (RLA). Because there is also no radial component of electric field at the cathode, the electron beam starts almost parallel and is matched to a solenoidal transport system with minimum increase in divergence and radius. The electrode emission surface is specified by an area covered with felt which undergoes explosive electron emission at low electrical field stresses (60 kV/cm). The 1.7 MV, 4.8-kA produced beam is transported 1.5 meters to the injection region of the racetrack via a system of solenoids and focusing coils. The maximum transverse velocity component at injection point (1.5 m downstream from the cathode surface) is #beta# perpendicular = 0.03 and the radius r = 2.8 cm which give a quite small beam emittance #epsilon# = 0.08 rad-cm. Three- dimensional numerical simulations suggest that ...

International Nuclear Information System (INIS)

A prototype electron applicator system providing circular and rectangular fields for use in intraoperative electron beam therapy with a Varian Clinac 18 linear accelerator has been fabricated. The dosimetric properties of this system for a variety of electron-beam energies, applicator sizes, and x-ray collimator settings was documented. Significant findings include: (a) surface dose values are in excess of 90% for electron energies of 12 MeV and above; (b) for the 18-MeV beam, the deepest depth where the central axis dose is 90% of its maximum value is in excess of 50 mm for circular applicators whose diameters are in excess of 5 cm; and (c) the treatment time to deliver 1000 rads ''given dose'' (at a given dose rate of 300 MU/min) is on the order of 3--4 min. Cross-field behavior is acceptable for the intended application and x-ray contamination is less than 4% for any applicator/electron energy combination. A system for irregular field ...

International Nuclear Information System (INIS)

In support of Stockpile Stewardship activities, accelerated aging tests on a plutonium alloy enriched with 7.3 at.% of "2"3"8Pu is underway using dilatometry at 35, 50, and 65 deg. C and immersion density measurements of materials stored at 50 deg. C. Changes in density are expected from radiation damage in the lattice and helium in-growth. After 25 equivalent years of aging, the dilatometry data shows that the alloys at 35 deg. C have expanded in volume by 0.11-0.12% and have started to exhibit a near linear expansion behavior primarily caused by the helium accumulation. The average He-to-vacancy ratio from tested specimens was determined to be around 2.55. The model for the lattice damage and helium in-growth accurately represents the volume swelling at 35 deg. C. The density converted from the dilatometry corresponds well to the decreasing density trend of reference plutonium alloys as a function of time.

Energy Technology Data Exchange (ETDEWEB)

The use of linear accelerators in radiotherapy is of great importance in Medicine, and according to international recommendations the electron beam dosimetry has to be performed using plane-parallel ionization chambers, previously calibrated in standard gamma radiation fields at accredited laboratories. In this work, calibration methods of plane-parallel ionization chambers used in dosimetry procedures of high energy electron beams of clinical accelerators were presented, tested and intercompared. The experiments were carried out using gamma radiation beams of {sup 60} Co at the Calibration Laboratory of Clinical Dosemeters at IPEN and electron beams od 4 to 16 MeV at the Radiotherapy Department of Hospital Israelita Albert Einstein, Sao Paulo. A method was chosen to be established at IPEN. Proposals of the calibration procedure, calibration certificate and data sheets are presented. (author)

CERN Document Server

We have measured $p_t$-dependent two-particle number correlations on azimuth and pseudorapidity for eleven centralities of $\\sqrt{s_{NN}} = 62$ and 200~GeV Au-Au collisions at STAR. 2D fits to these angular correlations isolate the azimuth quadrupole amplitude, denoted $2 v_2^2 \\{ 2D \\} ( p_t )$, from localized same-side correlations. Event-plane $v_2 ( p_t )$ measurements within the STAR TPC acceptance can be expressed as a sum of the azimuth quadrupole and the quadrupole component of the same-side peak. $v_2 \\{ 2D \\} ( p_t )$ can be transformed to reveal quadrupole $p_t$ spectra which are approximately described by a fixed transverse boost and universal L\\'evy form nearly independent of centrality. A parametrization of $v_2 \\{ 2D \\} ( p_t )$ can be factored into centrality and $p_t$-dependent pieces with a simple $p_t$ dependence above 0.75 GeV/c. Results from STAR are compared to published ...

International Nuclear Information System (INIS)

The studies using phantoms confirmed that the reduction of electron beam energy and minimization of X-ray contamination could be achieved when electron beam was interposed by an acrylic plate placed 20 cm anterior to a patient. Four patients of mycosis fungoides were treated with 8 MeV electron beam of a linear accelerator at UOEH Hospital from October 1981 to December 1986. Two of them were treated with this technique by placing 2 cm thick acrylic plate anterior to the patients and satisfactory results were obtained. Cutaneous lesions subsided remarkably with the dosage of 2000 cGy given in 2 months. Leucopenia due to bone marrow suppression was mild and the patients tolerated the treatment well. (author).

International Nuclear Information System (INIS)

In the past decade, considerable progress has been made on reducing the seismic response of structures through seismic isolation. Application of seismic-isolation techniques to nuclear power facilities is currently being investigated. This paper presents an analysis of the effect of long period motions on a seismic-isolated nuclear structure. Preliminary analysis indicates that long-period earthquake motions increase structural accelerations and relative displacements between the upper and lower mats. Relative displacement between the mats can be represented by spectral displacement at the frequency of the structure, and can be effectively reduced by increasing viscous damping in the isolator. The isolated structure behaves as a system with one degree of freedom. Future analysis of seismic effects on seismic-isolated structures should include the linear and nonlinear effects of soil-structure interactions. 3 refs., 12 figs., 3 tabs.

Science.gov (United States)

Because of its small cross section, the 88Sr(n,g) reaction is an important bottleneck during s-process nucleosynthesis. Hence, an accurate determination of this rate is needed to better constrain the neutron exposure in s-process models and to more fully exploit the recently discovered isotopic anomalies in certain meteorites. We have completed the resonance analysis of our new and improved measurements of the neutron capture and total cross sections for 88Sr made at the Oak Ridge Electron Linear Accelerator (ORELA). We describe our experimental procedures and resonance analysis, compare our results to previous data, and discuss their astrophysical impact.

Energy Technology Data Exchange (ETDEWEB)

It has been recently suggested by Arkani-Hamed, Dimopoulos and Dvali that gravity may become strong at energies not far above the electroweak scale and thus remove the hierarchy problem. Such a scenario can be tested at both present and future accelerators since towers of Kaluza-Klein gravitons and associated scalar fields now play an important phenomenological role. In this paper we examine several processes for their sensitivity to a low scale for quantum gravity including deep inelastic ep scattering at DESY HERA, high precision low energy {nu}N scattering, Bhabha and Mo/ller scattering at linear colliders and both fermion and gluon pair production at {gamma}{gamma} colliders. {copyright} {ital 1999} {ital The American Physical Society}

International Nuclear Information System (INIS)

It has been recently suggested by Arkani-Hamed, Dimopoulos and Dvali that gravity may become strong at energies not far above the electroweak scale and thus remove the hierarchy problem. Such a scenario can be tested at both present and future accelerators since towers of Kaluza-Klein gravitons and associated scalar fields now play an important phenomenological role. In this paper we examine several processes for their sensitivity to a low scale for quantum gravity including deep inelastic ep scattering at HERA, high precision low energy #nu#N scattering, Bhabha and Moller scattering at linear colliders and fermion pair production at #gamma##gamma# colliders

British Library Electronic Table of Contents (United Kingdom)

During the last few decades, accuracy in photon and electron radiotherapy has increased substantially. This is partly due to enhanced linear accelerator technology, providing more flexibility in field definition (e.g. the usage of computer-controlled dynamic multileaf collimators), which led to intensity modulated radiotherapy (IMRT). Important improvements have also been made in the treatment planning process, more specifically in the dose calculations. Originally, dose calculations relied heavily on analytic, semi-analytic and empirical algorithms. The more accurate convolution/superposition codes use pre-calculated Monte Carlo dose "kernels" partly accounting for tissue density heterogeneities. It is generally recognized that the Monte Carlo method is able to increase accuracy even furt...

Energy Technology Data Exchange (ETDEWEB)

Making use of a back-to-back type double fission chamber and a lead slowing-down spectrometer driven by a 46 MeV electron linear accelerator, the fission cross sections of Am-241, Am-242m and Am-243 have been measured relative to that of U-235 from 0.1 eV to 10 keV with the energy resolution of about 40 % full width at half maximum. Each of the measured result has been compared with (1) the evaluated nuclear data in ENDF/B-VI and JENDL-3.2, and (2) the existing experimental data, whose evaluated and measured data were broadened by the energy resolution function of the spectrometer.

Energy Technology Data Exchange (ETDEWEB)

In the rf-driven free-electron laser (FEL) at the Los Alamos National Laboratory, there are two pulsed-power rf modulators as sources for two tandem, side-coupled 20-MeV linear accelerators. The rf power used to control the cavity fields is supplied by two 5.5-MW modulating anode klystrons operating at a center frequency of 1300.2 MHz. The modulation of the 125 kV klystron is achieved by using a triode switch tube that provides a pulse width up to 300 ..mu..s and a pulse repetition rate up to 10 Hz. This paper describes the present configuration of these two duplicate systems and presents plans for meeting the requirements of future rf FEL experiments at Los Alamos. 12 refs., 5 figs.

International Nuclear Information System (INIS)

To investigate the 2D/1D fusion core analysis method, a 1D neutron transport problem solver, PEACH-ID, is developed. It is a code of method of characteristics (MOC), both the usual fiat-source step characteristics (SC) scheme and linear source (LS) approximation scheme are adopted for tracking calculation along the neutron flying trajectory. Exponential function interpolation table and fission source extrapolation are adopted as two major methods to accelerate the computational process. Numerical results demonstrate that PEACH-1D is accurate and efficient, and the proposed LS scheme is able to handle quite larger mesh division and deserves much more application in the MOC codes. (authors)

Energy Technology Data Exchange (ETDEWEB)

In the case of total skin electron therapy without the beam guide, the electron beam is scattered just outside the gantry exit, dose uniformity in the field is broken, and dose is spread outside the light field. The aims of this study were to measure the mean energy of the off-axis incident electron beam without the beam guide and to establish a reference for the clinical situation. For the measurement, a 4 MeV electron beam was selected among several energies from the linear accelerator. A scintillating fiber beam energy monitor measured the mean energy of the incident electron beam. This energy monitor is a small, light-weight piece of equipment composed of a wedge absorber, scintillation fiber, and photodiode. We found the relationship between electron energy and the indicated value of the energy monitor by means of the estimation of correction factors for five different kinds of electron energy. The preferable linear ...

CERN Document Server

A Bragg curve ionization chamber for acceleration mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

The previous 58Ni and 60Ni set of resonance parameters (ENDF/B-VII-0, JEFF-3, etc.) was based on the SAMMY analysis of Oak Ridge National Laboratory neutron transmission, scattering cross section and capture cross section measurements by C. M. Perey et al. The present results were obtained by adding to the SAMMY experimental data base the capture cross sections measured recently at the Oak Ridge Linear Electron Accelerator by Guber et al. and the Geel Electron Linear Accelerator very high-resolution neutron transmission measurements performed by Brusegan et al. A complete resonance parameter covariance matrix (RPCM) was obtained from the SAMMY analysis of the experimental database. The data sets were made consistent, when needed, by adjusting the neutron energy scales, the normalization coefficients, and the background corrections. The RPCM allows the calculation of the cross section uncertainties due ...

International Nuclear Information System (INIS)

During the last few decades, accuracy in photon and electron radiotherapy has increased substantially. This is partly due to enhanced linear accelerator technology, providing more flexibility in field definition (e.g. the usage of computer-controlled dynamic multileaf collimators), which led to intensity modulated radiotherapy (IMRT). Important improvements have also been made in the treatment planning process, more specifically in the dose calculations. Originally, dose calculations relied heavily on analytic, semi-analytic and empirical algorithms. The more accurate convolution/superposition codes use pre-calculated Monte Carlo dose 'kernels' partly accounting for tissue density heterogeneities. It is generally recognized that the Monte Carlo method is able to increase accuracy even further. Since the second half of the 1990s, several Monte Carlo dose engines for radiotherapy treatment planning have been introduced. To enable the use of a ...

Energy Technology Data Exchange (ETDEWEB)

The Linac Coherent Light Source (LCLS) is an X-ray free-electron laser (FEL) project based on the SLAC linac [1]. With its nominal set of electron beam, focusing and undulator parameters, it is designed to achieve SASE saturation at an undulator length of about 100 m with an average power of 10 GW. In order to keep the electron beam focused in the undulators, a FODO lattice is integrated along the entire length of the undulators. Nominally, the quadrupole strengths are chosen to produce nearly constant betafunction and beam size along the undulator, optimized for the FEL interaction in the exponential growth regime. Since these quadrupoles are electromagnetic, it is possible to adjust the individual quadrupole strength to vary the betafunction and the beam size along the undulator, tailoring the FEL interaction in the start-up and the saturation regimes. In this paper, we present simulation studies of the tapered ...

Energy Technology Data Exchange (ETDEWEB)

The main physical processes allowing negative ion production by surface sputtering for further acceleration in tandem acceleration are briefly reviewed. The sputtering yield and the probability of negative ion ejection are discussed. The properties of negative ion beams for an efficient acceleration in tandem accelerators are also discussed, with an emphasis on space charge problems. The main features and performances of the heavy negative ion injector of the Bucharest tandem accelerator are given.

British Library Electronic Table of Contents (United Kingdom)

Solid molecular orthohydrogen exhibits orientational order at low temperatures. The orthohydrogen molecules, which are quadrupoles, order in the Pa3 structure. We have simulated this ordering, and explored the behaviour under dilution by spherical parahydrogen molecules.

Energy Technology Data Exchange (ETDEWEB)

We discuss the algebraic structure of the generator coordinate method for triaxial quadrupole collective motion. The collective solutions are classified according to the representations of the permutation group of the intrinsic axes. Our method amounts to an approximate angular-momentum projection. We apply it to a study of the spherical-to-deformed-shape transition in light even strontium isotopes {sup 78-88}Sr. We find that triaxial configurations play a significant role in explaining the structure of the transitional isotopes {sup 80-82}Sr. (orig.).

International Nuclear Information System (INIS)

Properties of unique parity states in odd-proton (_7_7Ir, _7_9Au) and odd-neutron nuclei (_7_8Pt) are investigated in the framework of the interacting boson-fermion approximation model. The core (boson)-particle (fermion) interaction is represented by a quadrupole-quadrupole interaction and an exchange term, which takes into account the effects of the Pauli exclusion principle. The even-even core nucleus is described in terms of the IBA-1 hamiltonian. The change in the properties of the corresponding odd-A nuclei can be interpreted in terms of a transition of the core hamiltonian between the O(6) and SU(3) limiting cases. (orig.).

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

Energy Technology Data Exchange (ETDEWEB)

Portal verification images were generated from the photon contamination in electron beams produced by a linear accelerator during treatment of patients receiving high-energy electron radiation therapy (8-14 MeV). An experimental storage phosphor system was used to record the images and display them on laser-printed film. Images were obtained from four or more treatment fractions from 21 cases of head and neck cancer. Precision in field placement was estimated by determining the position of a selected anatomic landmark relative to the center of the field for each series of images. The average standard deviation in the field-position measurements was 3.8 mm. Several procedural problems were also detected and corrected after review of the verification images. The results indicate that the emphasis placed on monitoring and control of field-positioning error in high-energy electron treatments should be similar to the emphasis placed on this aspect ...

Energy Technology Data Exchange (ETDEWEB)

Beyond a great number of applications in mineral process, the hydrocyclone separation has been used recently in an increasing number of fields, such as: environmental engineering, petrochemical engineering, food engineering, electrochemical engineering, pulp bioengineering, processes and paper industries, among others. Nowadays, the produced water is treated and then reinjected in the surface and also in return to the formation. In the offshore platforms, the produced water can be directly discarded in the ocean, since the dispersed phase concentration (oil) is according to Brazilian regulating agency limits. The basic principle used in hydrocyclone separation is the centrifugal sedimentation machine: the suspended particles are submitted to centrifugal acceleration, which separates them from the fluid. The basic geometry of a hydrocyclone consists of four parts: a cylindrical section for feeding, a conical section for swirling, an overflow and an under flow. The ...

Energy Technology Data Exchange (ETDEWEB)

Power system stabilizers (PSSs) are used to enhance damping of power system oscillations through excitation control of synchronous generator. The objective of the PSS is to generate a stabilizing signal, which produces a damping torque component on the generator shaft. Conventional PSSs are designed with the phase compensation technique in the frequency domain and include the lead-lag blocks whose parameters are determined according to a linearized power system model. The performance of conventional PSSs (CPSSs) depends upon the generator operating point and the system parameters, but a reasonable level of robustness can be achieved depending on the tuning method. This paper presents a new three-dimensional PSS (3D PSS), which uses rotor speed deviation, rotor acceleration and load angle deviation as input signals. The 3D PSS attempts to return the generator to the state-space origin, based on the generator's trajectory in state-space ...

Energy Technology Data Exchange (ETDEWEB)

The standing-wave free-electron laser (FEL) differs from a conventional linear-wiggler microwave FEL in using irises along the wiggler to form a series of standing-wave cavities and in reaccelerating the beam between cavities to maintain the average energy. The device has been proposed for use in a two-beam accelerator (TBA) because microwave power can be extracted more effectively than from a traveling-wave FEL. The standing-wave FEL is modeled in the continuum limit by a set of equations describing the coupling of a one-dimensional beam to a TE{sub 01} rectangular-waveguide mode. Analytic calculations and numerical simulations are used to determine the time variation of the reacceleration field and the prebunching required so that the final microwave energy is the same in all cavities. The microwave energy and phase are found to be insensitive to modest spreads in the beam energy and phase and to errors in the reacceleration field and the ...

Energy Technology Data Exchange (ETDEWEB)

Wonderful opportunities await particle physics over the next decade, with the coming of the Large Hadron Collider at CERN to explore the 1-TeV scale (extending efforts at LEP and the Tevatron to unravel the nature of electroweak symmetry breaking) and many initiatives to develop our understanding of the problem of identity: what makes a neutrino a neutrino and a top quark a top quark. Here I have in mind the work of the B factories and the Tevatron collider on CP violation and the weak interactions of the b quark; the wonderfully sensitive experiments at Brookhaven, CERN, Fermilab, and Frascati on CP violation and rare decays of kaons; the prospect of definitive accelerator experiments on neutrino oscillations and the nature of the neutrinos; and a host of new experiments on the sensitivity frontier. We might even learn to read experiment for clues about the dimensionality of spacetime. If we are inventive enough, we may be able to follow this rich menu with the ...

International Nuclear Information System (INIS)

The fission cross section of /SUP 242m/ Am has been measured from 0.005 eV to 20 MeV using time-of-flight techniques at the Oak Ridge Electron Linear Accelerator. A hemispherical plate fission ionization chamber with five pairs of plates contained three deposits totaling 507 #mu#g of /SUP 242m/ Am, one deposit of 168 #mu#g "2"3"5U, and a ''weightless'' deposit of "2"5"2Cf, which served as a monitor of chamber performance. The fission of "2"3"5U, served as the cross-section standard for energies above 101 keV while "6Li(n,#alpha#), normalized to "2"3"5U fission in the 7.8- to 11.0-eV interval, served as a shape standard below 101 keV. Approximately 360 h of data were obtained at a flight path distance of 9.1 m, primarily with 40-ns bursts. Particular attention was paid to correction of backgrounds, especially inscattered-neutron-induced events. The fission resonance integral was found to be 1800 + or - 65 b.

Energy Technology Data Exchange (ETDEWEB)

Perforated thermoplastic masks are used to provide patients immobilization. This procedure inserts a material in the path of the radiation beam, that attenuates and modifies the beam fluence and flatness. The present study evaluates the increase in skin dose as a result of using thermoplastic masks. Relative doses were measured on the surface of a solid water phantom, in the presence and absence of masks. These masks were stretched according to deformation patterns observed in clinical routine. The measurements were obtained with a plane-parallel chamber (Markus type 23343) and radiochromic film (EBT Gafchromic) for 6MV X-rays from a linear accelerator, and for a radiation beam from a cobalt therapy unit. The results showed that thermoplastic masks, whose thickness varied between 2 and 3 mm, increased the dose on the surface by a factor of 3. Due to the variations in the skin dose distribution, clinical procedures were suggested to minimize ...

International Nuclear Information System (INIS)

The authors have designed and constructed four types of electron-beam diodes for the new 4-MV RLA injector: a non-immersed foilless diode, a magnetically immersed foilless diode, a foil diode and an ion-focused foilless diode, They are tailored to fit the new injector cavity. The design goals were to produce high quality 10-kA to 20-kA electron beams with a #beta# perpendicular smaller than 0.2 and a beam radius of the order of 2 cm. These beams will be matched to the RLA IFR channel so #beta# perpendicular must be equal to or smaller than the square root of the ratio of the beam current versus Alfven current for f_e = 1. A reentrant anode geometry was selected for the injector cavity design, because it offers substantial savings on the required amount of feromagnetic cores. The inner radius of the outside shell, now only 30 cm, would have been twice as large (60 cm) if a coaxial non-reentrant geometry had been adopted. The shape of the anode and cathode electrodes were carefully ...

Energy Technology Data Exchange (ETDEWEB)

A silicon capacitive accelerometer was fabricated to detect subsurface elastic waves by using micromachining technology. Characteristics required for it call for capability of detecting acceleration with amplitudes from 0.1 to 1 gal and flat amplitude characteristics in frequency bands of 10 Hz to several kHz. For the purpose of measuring transition phenomena, linear phase characteristics in the required bands must be guaranteed, cross sensitivity must be small, and resistance to water, pressure and heat is demanded. Sensitivity of the sensor is determined finally by noise level in a detection circuit. The sensor`s minimum detection capability was 40 mgal in the case of the distance between a weight and an electrode being 3 {mu}m. This specification value is a value realizable by the current micromachining technology. Dimensions for the weight and other members were decided with the natural frequency to make band width 2 kHz set to 4 kHz. ...

CERN Document Server

Modified gravity theories may provide an alternative to dark energy to explain cosmic acceleration. We argue that the observational program developed to test dark energy needs to be augmented to capture new tests of gravity on astrophysical scales. Several distinct signatures of gravity theories exist outside the linear regime, especially owing to the screening mechanism that operates inside halos like the Milky Way to ensure that gravity tests in the solar system are satisfied. This opens up several decades in length scale and new classes of galaxies at low-redshift that can be exploited by surveys. While theoretical work on models of gravity is in the early stages, we can already identify new regimes which cosmological surveys could target to test gravity. These include: 1. A small scale component that focuses on the interior and vicinity of galaxy and cluster halos. 2. Spectroscopy of low redshift galaxies, especially galaxies smaller than ...

International Nuclear Information System (INIS)

Purpose/Objective: With the advent of computed tomography and magnetic resonance imaging, the three dimensional representation of the patient anatomy has become an invaluable resource for better diagnosis and delineation of the target volume and sensitive structures in radiation therapy. Although the therapeutic linear accelerator industry has made available highly sophisticated equipment, the aggressiveness in dose prescription and delivery has to be complimented by accurate dose computation methods. We have adopted a convolution/superposition algorithm for the calculation of absolute dose that fully accounts for the external shape and internal structure of the patient for photon treatment radiotherapy. In this paper, we will discuss the principles of the convolution algorithm and we will show how the computed dose compares to clinically relevant treatment techniques. Materials and Methods: A computer controlled data acquisition system and a ...

International Nuclear Information System (INIS)

A Siemens Mevatron KV2 accelerator installed at the Royal Adelaide Hospital employs cylindrical solid-walled electron cones for some electron collimation. The cones being used at present result in treatment fields that do not always conform with the International Electrotechnical Commission (IEC) Standards (particularly at high energies). The aim of this project was to simulate the existing cones using Monte Carlo methods in order to evaluate potential cone modifications required to overcome the field irregularities. Simulations were performed using the EGS4 (Electron Gamma Shower version 4, distribution II) Monte Carlo code installed on a DEC Alpha workstation at the University of South Australia. To rigorously simulate the existing electron cones it was necessary to also simulate various components within the treatment head of the linear accelerator. Results of simulations for existing cones were found to be consistent ...

International Nuclear Information System (INIS)

In radiotherapy treatment planning, convolution/superposition algorithms currently represent the best practical approach for accurate photon dose calculation in heterogeneous tissues. In this work, the implementation, accuracy and performance of the FFT convolution (FFTC) and multigrid superposition (MGS) algorithms are presented. The FFTC and MGS models use the same 'TERMA' calculation and are commissioned using the same parameters. Both models use the same spectra, incorporate the same off-axis softening and base incident lateral fluence on the same measurements. In addition, corrections are explicitly applied to the polyenergetic and parallel kernel approximations, and electron contamination is modelled. Spectra generated by Monte Carlo (MC) modelling of treatment heads are used. Calculations using the MC spectra were in excellent agreement with measurements for many linear accelerator types. To speed up the calculations, a number of ...

International Nuclear Information System (INIS)

A scheme for on-line tuning of a fuzzy-logic power system stabilizer is presented. firstly, a fuzzy-logic power system stabilizer is developed using speed deviation and accelerating power as the controller input variables. The inference mechanism of fuzzy-logic controller is represented by a decision table, constructed of linguistic IF-THEN rules. The Linguistic rules are available from experts and the design procedure is based on these rules. It assumed that an exact model of the plant is not available and it is difficult to extract the exact parameters of the power plant. Thus, the design procedure can not be based on an exact model. This is an advantage of fuzzy logic that makes the design of a controller possible without knowing the exact model of the plant. Secondly, two scaling parameters are introduced to tune the fuzzy-logic power system stabilizer. These scaling parameters are the outputs of another fuzzy-logic system, which gets the operating conditions ...

Science.gov (United States)

Spline functions associated with a general linear differential operator L which interpolate prescribed data with respect to arbitrary linear functionals are investigated. (Author)

Energy Technology Data Exchange (ETDEWEB)

RHIC 8 cm aperture dipole magnets and quadrupole cold masses are being built for Brookhaven National Laboratory (BNL) by Northrop Grumman Corporation at a production rate of one dipole magnet and two quadrupole cold masses per day. This work was preceded by a lengthy Technology Transfer effort which is described elsewhere. This paper describes the tooling which is being used for the construction effort, the production operations at each workstation, and also the use of trend plots of critical construction parameters as a tool for monitoring performance in production. A report on the improvements to production labor since the start of the programs is also provided. The magnet and cold mass designs, and magnetic test results are described in more detail in a separate paper.

International Nuclear Information System (INIS)

Optimization of radiation shielding for a medium energy accelerator with 60 MeV alpha ions is carried out using the cost-benefit approach. Cost optimum shield thicknesses are estimated for different operating conditions of the accelerator. (author). 5 refs, 1 tab.

Energy Technology Data Exchange (ETDEWEB)

Ion acceleration has now been demonstrated with the IFA-2 collective ion accelerator system. The IFA-2 system is described, photoionization experiments are summarized, and ion results are presented. Using a 1 MeV electron beam and a 30 cm acceleration length, IFA-2 has produced 5 MeV H/sup +/, 10 MeV D/sup +/, and 20 MeV He/sup + +/. This means that accelerating fields of 33 MV/m over 30 cm have been achieved with a controlled collective accelerator for the first time.

International Nuclear Information System (INIS)

The major projects of the Los Alamos National Laboratory's Accelerator Technology Division are discussed, covering activities that occurred during the first six months of calendar 1982.

International Nuclear Information System (INIS)

Nucleon decay of underbarrier one-quasiparticle states with large angular momentum in soft spherical nuclei is considered. It is shown that energy dependences of differential probabilities of nucleon decay to the ground (0"+) and first excited (2"+) states of daughter nucleus differ qualitatively from each other due to strong interaction between quasiparticles and low-lying quadrupole states.

Energy Technology Data Exchange (ETDEWEB)

The method of double microwave--radio-frequency resonance has been used to obtain spectra of the 2/sub 11/reverse arrow2/sub 12/ and 3/sub 21/reverse arrow3/sub 22/ transitions in HCOOD, DCOOH, and HCOOH molecules. The constants of the quadrupole bond of the deuterons have been determined, magnetic interactions being taken into acocunt. A comparison with results of previous studies is given.

Energy Technology Data Exchange (ETDEWEB)

In this letter we report a clear and unambiguous observation of the out-of-plane quadrupole magnetic field suggested by numerical simulations in the reconnecting current sheet in the Magnetic Reconnection Experiment (MRX). Measurements show that the Hall effect is large in collisionless regime and becomes small as the collisionality increases, indicating that the Hall effect plays an important role in collisionless reconnection.

Energy Technology Data Exchange (ETDEWEB)

An add-on multileaf collimator for electrons (eMLC) has been developed that provides computer-controlled beam collimation and isocentric dose delivery. The design parameters result from the design study by Gauer et al (2006 Phys. Med. Biol. 51 5987-6003) and were configured such that a compact and light-weight eMLC with motorized leaves can be industrially manufactured and stably mounted on a conventional linear accelerator. In the present study, the efficiency of an initial computer-controlled prototype was examined according to the design goals and the performance of energy- and intensity-modulated treatment techniques. This study concentrates on the attachment and gantry stability as well as the dosimetric characteristics of central-axis and off-axis dose, field size dependence, collimator scatter, field abutment, radiation leakage and the setting of the accelerator jaws. To provide isocentric irradiation, the eMLC can ...

Science.gov (United States)

No Abstract Available

CERN Document Server

A last look at the green field, in the triangular wedge of land stray radiation near the CERN accelerators.

KoreaScience (Korea)

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KoreaScience (Korea)

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International Nuclear Information System (INIS)

In the procedure of the hydraulic control system analysis, a linearized approximate equation described by the first order term of Taylor's series has been widely used. Such a linearized equation is effective just near the operating point. In this study, the authors estimate computational errors in the process of applying the existing linearized equation stated above. For evaluating the computational accuracy in practical applications of the linearized equations, dynamic behaviors of hydraulic control systems are investigated through simulations with several kinds of representative hydraulic systems and the linearized equations suggested in this study.

International Nuclear Information System (INIS)

The current status of research and development in the realm of physics and technology of collective ion acceleration in systems with a virtual cathode (VC) is reviewed. Three major acceleration methods and devices developed on their basis are considered: reflex triodes and their modifications, gas-filled vircators, and vacuum vircators with a Luce diode. Experimental data are outlined and the principal physical models interpreting these data are described. New ion acceleration techniques whose realization involves the production and disappearance of the VC are also discussed. All methods of collective ion acceleration are compared and the possible ways for the further development of this promising scientific field are highlighted. (reviews of topical problems)

Energy Technology Data Exchange (ETDEWEB)

This study reports the observation of the decays B{sup 0}{yields}D{sup (*)+}{sub S}{pi}{sup -} and B{sup 0}{yields}D{sup (*)-}K{sup +} in a sample of 230 x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} events collected with the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} storage ring, located at the Stanford Linear Accelerator Center. The branching fractions {beta}(B{sup 0} {yields} D{sup +}{sub S}{pi}{sup -}) = (1.3 {+-} 0.3 (stat) {+-} 0.2 (syst)) x 10{sup -5}, {beta}(B{sup 0} {yields} D{sup +}{sub S}K{sup +}) = (2.5 {+-} 0.4 (stat) {+-} 0.4 (syst)) x 10{sup -5}, {beta}(B{sup 0}{yields}D{sup (*)+}{sub S}{pi}{sup -}) = (2.8 {+-} 0.6 (stat) {+-} 0.5 (syst)) x 10{sup -5}, and {beta}(B{sup 0}{yields}D{sup (*)-}K{sup +}) = (2.0 {+-} 0.5 (stat) {+-} 0.4 (syst)) x 10{sup -5} are measured. The significance of the measurements to differ from zero are 5, 9, 6, and 5 standard deviations, respectively. This is a first observation of the ...

International Nuclear Information System (INIS)

Stereotactic radiosurgery (SRS) precisely delivers high-dose radiation to a small target (usually less than 3-4 cm in diameter), in a single session with steep dose-fall, employing various radiation methods. SRS provides good tumor control for small brain metastases from various primary cancers, with minimal untoward effects on surrounding normal brain. This excellent tumor control prevents neurological death and maintains good activity of daily life. Although surgery with whole-brain radiation therapy (WBRT) remains an important option for patients with a solitary brain metastasis, SRS with or without WBRT should be considered in patients with a limited number of small tumors and a good prognosis. Many reports, as well as both retrospective and prospective reviews, have shown WBRT before or after SRS to improve local control and reduce new distant lesion emergence. However, upfront WBRT does not improve survival. There are two major delivery techniques, Gamma Knife (GK; Elekta AB, ...

International Nuclear Information System (INIS)

As a series of estimations of population doses and of risk estimates from medical exposures in Japan, the malignancy significant dose (MSD) and the fatal malignant risk from beam therapy were estimated based on a nationwide survey of radiotherapeutic treatments, using a malignancy significant factor and a weighting factor determined from the data on the cancer mortality among the atomic bomb survivors in Nagasaki. The effective dose was defined as a sum of the product of the weighting factor and the organ or tissue doses with respect to the malignant diseases. The organ or tissue doses were determined with ionization chambers placed at the positions of their center in a MixDp-phantom simulated lung tissues by a block of cork, using a telecobalt unit, a conventional X-ray unit and a medical linear accelerator. The organ or tissue doses were categorized into three dose components; namely 1) dose from useful beams; 2) scattered radiation dose from ...

International Nuclear Information System (INIS)

The study of tropospheric kinetics underlies global change because key greenhouse gases are photochemically active. Modeling of tropospheric chemistry on a global scale is essential because some indirect greenhouse gases are short-lived and interact in a non-linear fashion. It is also extremely challenging, however; the global change grid is extensive in both the physical and temporal domains, and critical lower atmospheric species include the organics and their oxidized derivatives, which are numerous. Several types of optimization may be incorporated into kinetics modules to enhance their ability to simulate the complete lower atmospheric gas phase chemical system. (1) The photochemical integrator can be accelerated by avoiding matrix and iterative solutions and by establishing families. Accuracy and mass conservation are sacrificed in the absence of iteration, but atom balancing is restorable post hoc. (2) Chemistry can be arranged upon the ...

International Nuclear Information System (INIS)

The implementation of a three-dimensional conformal radiotherapy facility in the radiotherapy department of the Heinrich Heine University is described. Complex radiotherapy techniques with commercially available networked systems are introduced to improve clinical work. Over 18 month we have gained clinical experience with a PHILIPS Multileaf Collimator (MLC) mounted on a SL 25 linear accelerator. For a limited period the MLC was used as a conventional blocking device. The standard MLC-shapes are controlled with a stand-alone computer system. In addition, a three-dimensional treatment planning system (3-D-TPS / TMS-Radix, Helax AB) based on convolution/superposition algorithms was recently installed. Treatment optimization is achieved using static field arrangements with complete volumetric computerized tomographic patient data for 3-D-TPS. Conformal adaptation of the 95%-isodose to the Planning Target Volume (PTV, ICRU 50) results in ...

International Nuclear Information System (INIS)

Increasing frequency of skin cancer, mycosis fungoides, Kaposi sarcoma etc, it need to treatment dose planning for total skin electron beam (TSEB) therapy. Appropriate treatment planning for TSEB therapy is needed to give homogeneous dose distribution throughout the entire skin surface. The energy of 6 MeV electron from the 18 MeV medical linear accelerator was adapted for superficial total skin electron beam therapy. The energy of the electron beam was reduced to 4.2 MeV by a 0.5cmx90cmx180cm acryl screen placed in a feet front of the patient. Six dual field beam was adapted for total skin irradiation to encompass the entire body surface from head to toe simultaneously. The patients were treated behind the acryl screen plate acted as a beam scatterer and contained a parallel-plate shallow ion chamber for dosimetry and beam monitoring. During treatment, the patient was placed in six different positions due to be homogeneous dose distribution ...

International Nuclear Information System (INIS)

Purpose: To report our clinical experiences with on-board imager (OBI) kV image verification for cranial stereotactic radiosurgery (SRS) and radiotherapy (SRT) treatments. Methods and Materials: Between January 2007 and May 2008, 42 patients (57 lesions) were treated with SRS with head frame immobilization and 13 patients (14 lesions) were treated with SRT with face mask immobilization at our institution. No margin was added to the gross tumor for SRS patients, and a 3-mm three-dimensional margin was added to the gross tumor to create the planning target volume for SRT patients. After localizing the patient with stereotactic target positioner (TaPo), orthogonal kV images using OBI were taken and fused to planning digital reconstructed radiographs. Suggested couch shifts in vertical, longitudinal, and lateral directions were recorded. kV images were also taken immediately after treatment for 21 SRS patients and on a weekly basis for 6 SRT patients to assess any intrafraction changes. ...

International Nuclear Information System (INIS)

The purpose of this study is to evaluate the accuracy of dose calculations by three algorithms. Depth dose, OPF (Output Factor) and dose profiles were measured in a heterogeneous phantom. These values were also calculated by three algorithms of the Batho power law (BPL), Equivalent-Tissue Air Ratio (ETAR) and Convolution superposition (CS). The data were obtained for 4, 6 and 10 MV photon beams with a linear accelerator (Varian 21EX). Field size ranged from 3 x 3 cm"2 to 10 x 10 cm"2. Dose profiles of beam penumbra were also measured by a 0.125 ml ionization chamber at the point of 8, 13 and 18 cm from the surface of the phantom at intervals of 1 mm. Differences between measured and calculated depth doses were within 2% in BPL and CS, but depth doses were overestimated in ETAR. OPFs were also overestimated with the error of more than 4% in ETAR. Absorbed dose calculated by CS were in agreement with the values measured by the ionization chamber. ...

KoreaScience (Korea)

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KoreaScience (Korea)

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Science.gov (United States)

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British Library Electronic Table of Contents (United Kingdom)

In this paper linear and nonlinear models of spacecraft attitude dynamics equations and gravity gradient moments are investigated. In addition, effects of gravity gradient moments on attitude dynamics of the satellite are studied. The purpose of this paper is to present a comparison between nonlinear and linear models of spacecraft attitude dynamics and gravity gradient moments in order to determine divergence of linear approximation from the nonlinear model. Simulation results indicate that designer of spacecraft attitude control subsystem should be meticulous in applying linear approximation of equations especially in low earth orbits. Consequently, finding an upper bound for small angle to keep the linear model valid and precise enough would be a vital part of using linear approximation...

CERN Document Server

A total of 50 000 tonnes of low-carbon steel sheet has been ordered for the LHC main magnets. After three years of production, about 10 000 tonnes of steel sheet have been produced by Cockerill-Sambre Groupe Usinor. This paper gives a summary of the manufacturing process and improvements implemented as well as an overview of the difficulties encountered during this production. Preliminary statistics obtained for the mechanical and magnetic steel properties are presented. (6 refs).

CERN Document Server

An anisotropic power spectrum will have a clear signature in the 21cm radiation from high- redshift hydrogen. We calculate the expected power spectrum of the intensity fluctuations in neutral hydrogen from before the epoch of reionization, and predict the accuracy to which future experiments could constrain a quadrupole anisotropy in the power spectrum. We find that the Square Kilometer Array will have marginal detection abilities for this signal at z~17 if the process of reionization has not yet started; reionization could enhance the detectability substantially. Pushing to higher redshifts and higher sensitivity will allow highly precise (percent level) measurements of anisotropy.

Energy Technology Data Exchange (ETDEWEB)

The schematic model is extended to open-shell nuclei. The quasiparticle random-phase approximation plus core polarization are used to calculate multipole matrix elements M/sub n/ and M/sub p/. Calculated trends in the ratio of deformation parameters ..beta../sub n//..beta../sub p/ are compared with experimental ratios for several sets of isotopes and isotones. The systematics indicate a rather abrupt change toward equality of ..beta../sub n/ and ..beta../sub p/ when N or Z is changed from a closed-shell value.

Energy Technology Data Exchange (ETDEWEB)

A model of a solid disordered ortho-parahydrogen mixture with infinite long-range interaction J/sub ij/ between orthomolecules distributed in accordance with a normal law with first moment J/sub 0/ is investigated. It is shown that the introduction of an external electric field gradient ..gamma.. can give rise to a phase transition to an orientational phase. The possible existence of an orientational glass phase is established. The influence of the degeneracy of the hydrogen orthomolecules on the low-temperature thermal properties of these systems is demonstrated, and a condition of stability of the replica-symmetric solution is established. At low temperatures, this solution is stable for a large value of ..gamma.. or J/sub 0/.nctio

International Nuclear Information System (INIS)

Lifetimes have been measured in the #pi#h_9_/_2 (yrast) and #pi#i_1_3_/_2 (excited) bands in the nuclei "1"8"1Ir and "1"8"7Au using the Recoil Distance Method (RDM). The results clearly indicate that the #pi#i_1_3_/_2 band exhibits an increased deformation over the #pi#h_9_/_2 band, in keeping with the premise that the delayed crossing in this band is due to enhanced quadrupole deformation. (author). 3 refs, 1 fig, 2 tab.

International Nuclear Information System (INIS)

The high-spin states in transitional odd-mass nuclei are studied in terms of an odd quasi-particle coupled to an asymmetric rotor with a variable moment of inertia (VMI). In order to take into account the VMI, the basis states are expanded in terms of the core eigenfunctions. Excitation energies, quadrupole moments, magnetic moments, B(E2) values and B(M1) values are calculated and compared with the experimental data for nuclei in Au and La regions. On comparison with other descriptions it is found that the treatment with VMI provides a more satisfactory explanation of the data. (Auth.).

International Nuclear Information System (INIS)

Differential cross sections have been measured for the elastic and inelastic scattering of 104 MeV alpha-particles from "9"0,"9"2Zr. The experimental data are analyzed in terms of coupled channels on the basis of a flexible anharmonic vibrator model and using different parametrizations of the radial shape of the extended optical potential. The results favour the squared Saxon-Woods type for the real part. Additionally to a radial momentum analysis of the real potentials a semimicroscopic folding model has been invoked for extracting isoscalar quadrupole and hexadecapole transition rates. (orig.).

UK PubMed Central (United Kingdom)

We describe the lethal, recessive accelerated-cell-death11 Arabidopsis mutant (acd11). Cell death in acd11 exhibits characteristics of animal apoptosis...Full Text Available

International Nuclear Information System (INIS)

A simple beam-forming system is described for the electrostatic accelerator of the Scientific-Research Institute of Nuclear Physics of Moscow State University. The system allows the beam to be focused on targets at various distances for a conductor potential of from 1 to 4 MV and beam currents of up to 35 #mu# A.

Science.gov (United States)

The major projects of the Los Alamos National Laboratory's Accelerator Technology Division are discussed, covering activities that occurred during the first six months of calendar 1982.

UK PubMed Central (United Kingdom)

OBJECTIVE: To increase cost-efficiency while maintaining the standard of medical care, an accelerated surgical stay program for patients having breast surgery was instituted. SUMMARY BACKGROUND DATA:...Full Text Available

International Nuclear Information System (INIS)

... beam monitoring betatrons delay circuits errors fluctuations gamma radiation

International Nuclear Information System (INIS)

(Sep 1973). United Kingdom Sinanoglu, O. Luken, W. Yale Univ., New Haven,

International Nuclear Information System (INIS)

The motivation for using a tandem electrostatic accelerator as an electron accelerator for a free electron laser (FEL) is presented. The adaptation of the HVEC EN tandem at the Weizmann Institute for this purpose, electron beam optics and nonlinear FEL computation relevant for this FEL realization are described. In the tandem configuration the terminal is held at a positive potential. The electron beam is accelerated from ground potential to the terminal in one beam tube and then decelerated down the other beam tube. The FEL wiggler and cavity are at the terminal. Due to the beam energy recovery this scheme produces a high power beam at the terminal with a small investment in electrical power. (orig.).

International Nuclear Information System (INIS)

(Jun 1984). United States Clough, RL Gillen, KT Sandia Nat'l Laboratories

British Library Electronic Table of Contents (United Kingdom)

Tthe acceleration of a liquid from a cylindrical container by the products of instantaneous detonation of a superimposed explosive charge (implosion method) is studies numerically in a two-dimensional formulation. Analytical formulas for the asymptotic velocities of liquid expansion and acceleration of the container body were obtained using numerical calculations in a one-dimensional approximation. The effect of the fracture of the body on the velocity of liquid expansion was studied in a two-dimensional formulation.

International Nuclear Information System (INIS)

The original purpose of this research was an investigation into the use of slow space charge waves on weakly relativistic electron beams for ion acceleration. The work had three main objectives namely, the development of a suitable ion injector, the growth and study of the properties of slow space charge waves on an electron beam, and a combination of the two components parts into a suitable proof of principle demonstration of the wave accelerator. This work focusses on the first two of these objectives.

Energy Technology Data Exchange (ETDEWEB)

The dielectric wall accelerator (DWA) system being developed at the Lawrence Livermore National Laboratory (LLNL) uses fast switched high voltage transmission lines to generate pulsed electric fields on the inside of a high gradient insulating (HGI) acceleration tube. High electric field gradients are achieved by the use of alternating insulators and conductors and short pulse times. The system is capable of accelerating any charge to mass ratio particle. Applications of high gradient proton and electron versions of this accelerator will be discussed. The status of the developmental new technologies that make the compact system possible will be reviewed. These include, high gradient vacuum insulators, solid dielectric materials, photoconductive switches and compact proton sources.

Energy Technology Data Exchange (ETDEWEB)

Compact dielectric wall (DWA) accelerator technology is being developed at the Lawrence Livermore National Laboratory. The DWA accelerator uses fast switched high voltage transmission lines to generate pulsed electric fields on the inside of a high gradient insulating (HGI) acceleration tube. Its high electric field gradients are achieved by the use of alternating insulators and conductors and short pulse times. The DWA concept can be applied to accelerate charge particle beams with any charge to mass ratio and energy. Based on the DWA system, a novel compact proton therapy accelerator is being developed. This proton therapy system will produce individual pulses that can be varied in intensity, energy and spot width. The system will be capable of being sited in a conventional linac vault and provide intensity modulated rotational therapy. The status of the developmental new ...

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

International Nuclear Information System (INIS)

The possibility to transform the future linear e"+e"-colliders into the #gamma#e and #gamma##gamma# colliders with approximately the same energies and luminosities was shown earlier. Their properties are compared from the point of view of possible physical investigations on them. 10 refs.; 1 tab.

UK PubMed Central (United Kingdom)

This article compared conceptual and empirical strengths of alternative methods for estimating racial disparities using non-linear models of health care access. Three methods were presented...Full Text Available

Science.gov (United States)

... Effect of checkpointing and queueing on program performance ... and a large class of stochastic linear ... problem is intrinsically related to K-terminal ...

International Nuclear Information System (INIS)

The control valve for a large steam turbine must be operated linearly to be run by an automatic control system in a power plant. It is, however, found that the flow increase is much greater for a given valve position change near the closed end of travel than it is near the open end. Accordingly, the desired linearization will be achieved if the valve is opened less near the closed end of travel and greater near the open end. The previous way for linearization was to utilize the cams, which is called the mechanical hydraulic control (MHC). The MHC was afterward improved by producing the nonlinear electric compensation to the nonlinear system of control valves, viz. the electro hydraulic control (EHC)

Science.gov (United States)

... The ultimate compressive strength was measured, and values for Young's modulus were calculated from the linear portion of the test curve. ...

Energy Technology Data Exchange (ETDEWEB)

Non-linear autoregressive Markov regime-switching models are intuitive. Time-series approaches for the modelling of electricity spot prices are frequently proposed. In this paper, such models are compared with an ordinary linear autoregressive model with regard to their forecast performances. The study is carried out using German daily spot-prices from the European Energy Exchange in Leipzig. Four non-linear models are used for the forecast study. The results of the study suggest that Markov regime-switching models provide better forecasts than linear models. (author)

Science.gov (United States)

... Both effects are undoubtedly caused by the ahaping of the spool valve flow characteristics The linear region of response corresponds to ...

Energy Technology Data Exchange (ETDEWEB)

A simple arrangement of standard horizontal coaxial Ge(Li) detectors with the aim of constructing a Compton linear-polarimeter was tested. High polarization sensitivity and detection efficiency were achieved. The characteristics of the polarimeter and analysis of the observed quantities in terms of the linear-polarization mixing coefficient Hsub(l)(LL') are described.

Science.gov (United States)

In this communication we propose a method to implement an all-optical astable multivibrator using the non-linear material based switches and logic gates. The scheme can operate in real time. The delay time can achieve ps(pico-second). The pulse duration can be made very low and may cross the THz easily by selecting proper material and laser source.

International Nuclear Information System (INIS)

The analysis of elastic and inelastic scattering of #alpha# particles with energy of 50 MeV by nuclei with mass numbers A=54-124 and of "3He particles by the nucleus "6"4Ni is given in the framework of the optical model. The parameters of multipole deformations for lower states are determined. The parameters for quadrupole and octupole deformations of the potential for the nucleus "1"1"2Sn are extracted, the values of the hexadecupole deformation #beta#_4 of the potential for nuclei "9"4Zr, "1"2"0","1"2"4Sn are found. Information is extracted on the ratio of deformation parameters for the neutron and proton components in lower collective states (2_1"+, 3_1"-) of nuclei with A=90-124.

Energy Technology Data Exchange (ETDEWEB)

The Muon Ionization Cooling Experiment (MICE) focusing solenoid magnets focus the muon beam within the MICE cooling channel on a liquid or solid absorber that is within the warm bore of solenoid. The focusing magnet has a warm bore of 470 mm. his magnet consists of two coils 210-mm long that is separated by an aluminum mandrel that is 200 mm long. Each of the coils has its own leads. The coils may be operated in either the non-flip mode (solenoid mode with both coils at the same polarity) or the lip mode (quadrupole focusing mode where both coils are at opposite polarity). This report describes the focusing solenoid magnet design that will be built by the vendor. The progress on the construction of the first of the focusing magnets will also be discussed in this report. Ultimately three of these magnets will be built. These magnets will be cooled using a pair 1.5 W (at 4.2 K) pulse tube coolers.

British Library Electronic Table of Contents (United Kingdom)

The crystal structure of Ca2RuD6 has been determined by neutron powder diffraction: space group Fm3m, K2PtCl6 structure, as found for other hexahydride salts of group 8 metals with alkaline earth or lanthanide counter ions. No structural phase transition was observed between 340K and 50K. The deuterium nuclear quadrupole coupling constant, 54.7kHz, leads to an ionic character of the Ru-D bond of 76%. The known trends in the behaviour of A2MH6 salts are interpreted in terms of the ionization energies of the cation and the central metal atom.

International Nuclear Information System (INIS)

Measurements are made on the principal magnetic susceptibilities and anisotropies of praseodymium selenate octahydrate single crystals in the temperature range 90 to 300 K. Although the effective magnetic moment is close to the free ion value, the anisotropy is quite high at room temperature. A least sequares fit of the Curie-Weiss law to the observed average susceptibility yields -36.5 K as the paramagnetic Curie temperature. An analysis of the results with a crystal field (CF) of D_4 symmetry, explains the observed results quite well. The CF and the spin-orbit interaction matrix is block diagonalized in the complete 33 dimensional basis of the "3H term in order to obtain the Stark energies and their eigenstates. Intermediate coupling effects are also considered. The ground state being a singlet, the g-factors are absent. Some predictions on the electronic heat capacity and the electronic quadrupole splitting are made in the light of the proposed CF. (author).

Energy Technology Data Exchange (ETDEWEB)

A sensitivity study that used the particle tracking code PARMELA was performed on the Advanced Free-Electron Laser (AFEL). The tolerances on the alignment of the beam-line elements and the magnetic-field strengths were examined. Two base-line configurations were determined at the beginning of the study. The electron beam was then matched into the wiggler. The optimized beam-line parameters were varied independently and their sensitivities were judged with the criterion that the free-electron laser (FEL) effective-detuning parameter should not fluctuate more than 10%. The results of this study set the specifications for the alignment, for the sensitivity of the steering magnets, and for the accuracy of the magnetic field in the quadrupoles and dipoles. 5 figs., 3 figs., 3 tabs.

Energy Technology Data Exchange (ETDEWEB)

More than 2,500 Moessbauer spectroscopic studies on minerals have been published since 1960. These papers contain approximately 8,000 sets of Moessbauer mineral data on at least 400 different minerals. This information has been compiled into a database that includes isomer shifts, quadrupole splittings, and magnetic hyperfine interactions at room, liquid nitrogen, and liquid helium temperatures. The database provides a profile of the Moessbauer research performed to date on minerals, including type and locality of minerals investigated, significance of the studies and results, and location of the research facilities. The data and information are available both in printed and magnetic form.With the establishment of this resource, the Moessbauer Effect Data Center has begun a systematic evaluation of the Moessbauer mineral data. It is anticipated that this resource can be used for the identification of minerals as powder X-ray diffraction data is.

CERN Document Server

We present a new set of 3.5 Post-Newtonian equations in which Newtonian hydrodynamics is coupled to the nonconservative effects of gravitational radiation emission. Our formalism differs in two significant ways from a similar 3.5 Post-Newtonian approach proposed by Blanchet (1993, 1997). Firstly we concentrate only on the radiation-reaction effects produced by a time-varying mass-current quadrupole $S_{ij}$. Secondly, we adopt a gauge in which the radiation-reaction force densities depend on the fourth time derivative of $S_{ij}$, rather than on the fifth, as in Blanchet's approach. This difference makes our formalism particularly well-suited to numerical implementation and could prove useful in performing fully numerical simulations of the recently discovered $r$-mode instability for rotating neutron stars subject to axial perturbations.

Energy Technology Data Exchange (ETDEWEB)

The control valve for a large steam turbine must be operated linearly to be run by an automatic control system in a power plant. It is, however, found that the flow increase is much greater for a given valve position change near the closed end of travel than it is near the open end. Accordingly, the desired linearization will be achieved if the valve is opened less near the closed end of travel and greater near the open end. The previous way for linearization was to utilize the cams, which is called the mechanical hydraulic control (MHC). The MHC was afterward improved by producing the nonlinear electric compensation to the nonlinear system of control valves, viz. the electro hydraulic control (EHC). This paper addresses the principle of linearization.

Energy Technology Data Exchange (ETDEWEB)

Radiation-and-thermal-combined degradation of ethylene-propylene rubber (EP rubber) and chlorosulfonated polyethylene (CSM) as cable insulating and jacketing materials were evaluated by accelerated aging tests and a method to assess the lifetime of these materials under practical application was studied. EP rubber and CSM of experimental formulation were degraded at accelerated rates, that are 50 [approx] 1000 times the degradation rate under a standard condition (1Gy/h, 50degC). The degradation was investigated by measuring the tensile properties. In the accelerated aging tests, rates of elongation decrease owing to degradation for both EP rubber and CSM were in proportion to increase in accelerated rate. Behaviors of elongation changes showed little difference with accelerated rate. EP rubber lifetime estimated from sequential aging test had a tendency to extend beyond that from ...

Energy Technology Data Exchange (ETDEWEB)

A study was conducted under the auspices of the Coordinating Research Council, Inc. (CRC) to assess the potential effects of gasoline octane quality on vehicle acceleration performance. Twelve participating laboratories, representing both the oil and the automotive industries, tested a total of 182 vehicles as part of the 1989 CRC Octane Number Requirement Survey. The vehicles consisted of 78 with electronic knock control systems and 104 without. All testing was performed using the 1989/1990 CRC FBRU fuel series. The results showed that acceleration performance of vehicles with knock sensors was significantly affected by gasoline octane quality. Octane effects on acceleration performance were most pronounced at maximum-throttle (detent) conditions and at octane levels below the vehicles' octane requirements; however, some knock-sensor vehicles did show improved acceleration performance with ...

Energy Technology Data Exchange (ETDEWEB)

This paper describes the results obtained from two large experimental facilities built at Sandia National Laboratories in Albuquerque, NM. FLAME (Flame Acceleration Measurements and Experiments) is a large horizontal rectangular channel designed to study flame acceleration, transition to detonation, simulation of combustion in containment geometries, component heating, and other problems in hydrogen combustion relevant to reactor safety. The Heated Detonation Tube has been designed to study detonations in hydrogen-air-steam mixtures. Both facilities have been in operation for just over a year. 12 figures.

Energy Technology Data Exchange (ETDEWEB)

Analytical and numerical calculations are presented for a reflexing electron beam type of collective ion accelerator. These results are then compared to those obtained through experiment. By constraining one free parameter to experimental conditions, the self-similar solution of the ion energy distribution agrees closely with the experimental distribution. Hence the reflexing beam model appears to be a valid model for explaining the experimental data. Simulation shows in addition to the agreement with the experimental ion distribution that synchronization between accelerated ions and electric field is phase unstable. This instability seems to further restrict the maximum ion energy to several times the electron energy.

Science.gov (United States)

and propels the projectile to a velocity sufficient to reach ..... CLF3 + N2 4 .... 5 inches or greater accelerates a finned projectile to the veloc ...

Science.gov (United States)

We study a two-level atom in interaction with a real massless scalar quantum field in a spacetime with a reflecting boundary. The presence of the boundary modifies the quantum fluctuations of the scalar field, which in turn modifies the radiative properties of atoms. We calculate the rate of change of the mean atomic energy of the atom for both inertial motion and uniform acceleration. It is found that the modifications induced by the presence of a boundary make the spontaneous radiation rate of an excited inertial atom oscillate near the boundary and this oscillatory behavior may offer a possible opportunity for experimental tests for geometrical (boundary) effects in flat spacetime. While for accelerated atoms, the transitions from ground states to excited states are found to be possible even in a vacuum due to changes in the vacuum fluctuations induced by both the presence of the boundary and the acceleration of atoms, ...

International Nuclear Information System (INIS)

... SBBN), Recife, PE (Brazil) INIS-BR--9282 108 p. PARTICLE ACCELERATORS

CERN Document Server

Particle accelerators are constructed and operated for a wide variety of applications. In particle physics - the branch of physics that studies the elementary constituents of matter and forces between them - high energy accelerators are used to look deep into the structure of matter. Medical particle accelerators are used for example in medicine to treat tumours [31], in imaging techniques such as Positron Emission Tomography (PET) [24], or for the radio-isotopes production. They also serve in many other industrial branches, e.g. geology, radiocarbon dating [39], molecular complex spectroscopy, lithography, food preservation etc. The eld of accelerator technology draws knowledge and expertise from a wide range of scientic disciplines and uses the latest technical knowledge. The incomplete list of covered disciplines includes mathematics, physics, electronics, computing, electromagnetic eld technology, ...

Energy Technology Data Exchange (ETDEWEB)

A compact proton accelerator for medical applications is being developed at Lawrence Livermore National Laboratory. The accelerator architecture is based on the dielectric wall accelerator (DWA) concept. One critical area to consider is the switch region. Electric field simulations and thermal calculations of the switch area were performed to help determine the operating limits of rmed SiC switches. Different geometries were considered for the field simulation including the shape of the thin Indium solder meniscus between the electrodes and SiC. Electric field simulations were also utilized to demonstrate how the field stress could be reduced. Both transient and steady steady-state thermal simulations were analyzed to find the average power capability of the switches.

CERN Multimedia

The next generation of particle accelerator is currently being designed at CERN. An understanding of the market forces in the computer industry will play a crucial role in the success of the project.

Energy Technology Data Exchange (ETDEWEB)

This volume is based on the proceedings of the CERN Accelerator School's course on Applied Geodesy for Particle Accelerators held in April 1986. The purpose was to record and disseminate the knowledge gained in recent years on the geodesy of accelerators and other large systems. The latest methods for positioning equipment to sub-millimetric accuracy in deep underground tunnels several tens of kilometers long are described, as well as such sophisticated techniques as the Navstar Global Positioning System and the Terrameter. Automation of better known instruments such as the gyroscope and Distinvar is also treated along with the highly evolved treatment of components in a modern accelerator. Use of the methods described can be of great benefit in many areas of research and industrial geodesy such as surveying, nautical and aeronautical engineering, astronomical radio-interferometry, metrology of ...

International Nuclear Information System (INIS)

An overview of different Ion Beam Analysis (IBA) techniques is given. Examples of applications of the PIXE techniques to various types of samples are presented. (author)

International Nuclear Information System (INIS)

Full text: A semiempirical algorithm for absorbed dose calculation at off-axis points in irregular beams was implemented. It is well known that semiempirical methods are very useful because of their easy implementation and its helpfulness in dose calculation in the clinic. These methods can be used as independent tools for dosimetric calculation in many applications of quality assurance. However, the applicability of such methods has some limitations, even in homogeneous media, specially at off axis points, near beam fringes or outside the beam. Only methods derived from tissue-air-ratio (TAR) or scatter-maximum-ratio (SMR) have been devised for those situations, many years ago. Despite there have been improvements for these manual methods, like the Sc-Sp ones, no attempt has been made to extend their usage at off axis points. In this work, a semiempirical formalism was introduced, based on the works of Venselaar et al. (1999) and Sanz et al. (2004), aimed to the Sc-Sp separation. This ...

International Nuclear Information System (INIS)

This paper extends the development of a new formulation of the theory of tachyons to encompass the dynamics of tachyons. Energy and momentum are discussed along with the proper mass of a tachyon. The transformation of force in extended relativity (ER) is derived. Acceleration in ER is also discussed, as well as the relationship between force and acceleration. Two simple examples relating to the motion of a charged tachyon are discussed, followed by a brief explanation of why tachyons cannot emit Cerenkov radiation in a vacuum. 13 refs., 3 figs.

Energy Technology Data Exchange (ETDEWEB)

Neutral beam systems for the next generation of magnetic fusion devices will be based on negative ions. Developments are progressing steadily, and large negative ion-based systems are under preparation for JT60-U and LHD, and are being considered for ITER. An overview of the physics of the production, acceleration and neutralization of large negative ion beams is given. The present state of the art in R and D is also surveyed. (Author).

International Nuclear Information System (INIS)

The salient features of the near-infrared free-electron laser (FEL) that is under construction at the new Darmstadt superconducting 130-MeV electron accelerator are discussed. Special attention is given to the layout and the parameters of the accelerator, the layout of the planned FEL experiment, the characteristics of the electron gun, the subharmonic chopper-buncher system, and the hybrid undulator system of the Darmstadt FEL. A comparison of the planned Darmstadt FEL with conventional lasers, with respect to the pulse and wavelength region, is presented. 15 refs.

International Nuclear Information System (INIS)

The structure of the P-2, S-1 accelerator mode with one step, S-1, on double period, P-2 for systems, described by the Harper mapping as well as by standard mapping, is analyzed. Detailed analysis of stability criteria is given and comparison with the results of numerical analysis is performed. Three-period compression of the P-2, S-1 island is revealed in the standard mapping. Refs. 7, figs. 7.

CERN Document Server

High energy muon colliders, such as the TeV-scale conceptual designs now being considered, are found to produce enough high energy neutrinos to constitute a potentially serious off-site radiation hazard in the neighbourhood of the accelerator site. A general characterization of this radiation hazard is given, followed by an order-of-magnitude calculation for the off-site annual radiation dose and a discussion of accelerator design and site selection strategies to minimize the radiation hazard.

Energy Technology Data Exchange (ETDEWEB)

This annual report describes research activities which have been performed with the JAERI tandem accelerator and the Van de Graaff accelerator from April 1, 2000 to March 31, 2001. Summary reports of 46 papers, and lists of publication, personnel and cooperative research with universities are contained. (author)

Energy Technology Data Exchange (ETDEWEB)

Accelerated aging tests such as high temperature burn-in, which are in current use on Bendix Kansas City Division's (BKC) purchased small and medium scale integrated circuits, were evaluated to determine if they are effective and necessary to ensure the required reliability. A theoretical analysis, a literature search, and a study of lot acceptance results were used to assess the value of integrated circuit burn-in.

Energy Technology Data Exchange (ETDEWEB)

An electron accelerator unit is described for electron beam therapy, comprising: a source of an electron beam; means for finally directing at least a portion of the beam to a therapy site, the directing means being mechanically independent of, and electrically isolated from, the source, and having a target area; and means for aligning the source with the directing means, the aligning means comprising means for projecting at least one beam of light from the source toward the target area.

UK PubMed Central (United Kingdom)

Using an anti-receptor mAb that blocks the attachment of echovirus 7 and related viruses (echoviruses 13, 21, 29 and 33), we have isolated a complementary DNA clone that encodes the human decay-accelerating...Full Text Available

CERN Document Server

We argue that the occurrence of late-time acceleration can conveniently be described by first-order general relativity covariantly coupled to fermions. Dark energy arises as a gravitationally driven BCS condensate of fermions which forms in the early universe. At late times, the gap and chemical potential evolve to have an equation of state with effective negative pressure, thus naturally leading to acceleration.

Science.gov (United States)

The accelerating flow of a lighter continuous phase through a heavier one is considered. Small nonuniformities grow into large ones due to the Rayleigh-Taylor instability. An experiment exemplifying the large bubble formation due to Rayleigh-Taylor instability was performed and simulated using the PHOENICS 84 computer code. The same numerical procedure was applied to the two-phase flow in a gun barrel. It shows that the acceleration provided by the movement of the projectile can cause initial nonuniformities to grow with time.

International Nuclear Information System (INIS)

A bibliography is presented of unclassified published and in-house technical material written by members of the Accelerator Technology Division, Los Alamos National Laboratory, since its inception in January, 1978. The author and subject concordances in this report provide cross-reference to detailed citations kept in a computer database and a microfilm file of the documents. The citations include an abstract and other notes, and can be searched for key words and phrases.

CERN Document Server

An S-brane solution with two non-composite electric branes and a set of l scalar fields is considered. The intersection rule for branes corresponds to the Lie algebra A_2. The solution contains five factor spaces with the fifth one interpreted as ``our'' 3-dimensional space. It is shown that there exists a time interval where accelerating expansion of ``our'' 3-dimensional space is compatible with small enough value of effective gravitational ``constant'' variation.

International Nuclear Information System (INIS)

The author discusses the accelerated aging tests performed using Hondo and Maya as aging resids with a commercial large pore hydrotreating catalyst. The results from these tests were compared with those obtained under a normal full life test. The test resid was a sample of a typical refinery charge and the activities for sulfur and vanadium removal were determined at 720"0F after successive brief periods of exposure to the heavier oils.