International Nuclear Information System (INIS)

Negative ions have attractive features as drivers for inertial confinement fusion, because they will avoid electron cloud effects, and could be efficiently photodetached to neutrals after the final focus, which could also be beneficial in heating warm dense matter targets. The halogens have large electron affinities, and thus should be able to produce high current densities of relatively robust negative ions. Recent experiments comparing chlorine beams to argon beams using the same source, extraction optics, and diagnostics have demonstrated that Cl"- beams can be produced with similar emittance to Ar"+ beams, and with about 34 the current density from the same configuration. The observed effective beam temperature of about 13eV, and the similarity of current densities show that negative halogen ...

International Nuclear Information System (INIS)

I present an exact calculation of free-electron-laser (FEL) eigenmodes (fundamental as well as higher order modes) in the exponential-gain regime. These eigenmodes specify transverse profiles and exponential growth rates of the laser field, and they are self-consistent solutions of the coupled Maxwell-Vlasov equations describing the FEL interaction taking into account the effects due to energy spread, emittance and betatron oscillations of the electron beam, and diffraction and guiding of the laser field. The unperturbed electron distribution is assumed to be of Gaussian shape in four dimensional transverse phase space and in the energy variable, but uniform in longitudinal coordinate. The focusing of the electron beam is assumed to be matched to the natural wiggler focusing in both transverse planes. With these assumptions the eigenvalue problem can be reduced ...

International Nuclear Information System (INIS)

The electron beam ion source (EBIS) at Texas A and M University was constructed and is currently undergoing tests on the injection and transmission of the electron beam through the solenoid. Results of computer simulation of the electron beam are presented, as well as measurements of electron beam profiles using a pinhole beam analyzer.

Energy Technology Data Exchange (ETDEWEB)

A study of the electron beam dynamics in the linac is conducted for the FERMI free electron laser (FEL) founded for construction at the Sincrotrone Trieste.

CERN Document Server

There may be circumstances when a sector has to be partially or totally warmed-up to temperatures above 80 K, that is when thermal dilatation starts to play a role. Some equipment have been identify as presenting a risk, like the non-conform "plug-in" modules in the arcs. Because of motion induced by thermal dilatation, the electrical (ElQA) quality control may also have to be done again after cool-down. The main reason identified so far for partial warm-up is the required maintenance of the cooling towers and the cryogenics plants. There is also the request from the vacuum group to periodically warm-up the beam screen to temperatures in the 100 K region to release and pump-out the gas crysorbed on the surface of the beam screen. Observed and expected temperature conditions and statistics on failures of PIMs in sectors which have been warmed-up will be presented ...

International Nuclear Information System (INIS)

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.

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Energy Technology Data Exchange (ETDEWEB)

A case is reported of a 23-year old male with multiple glomus tumours that showed marked involution after he had electron beam therapy. (author).

Science.gov (United States)

... attachment tube which is sketched in Fig. 1. It is mounted inside a cylindrical evacuated tube. A beam of thermal electrons ...

Science.gov (United States)

Not Available

Energy Technology Data Exchange (ETDEWEB)

The properties of negative-ion beams are very important for designing negative-ion apparatus and applications of negative-ion beams, especially, electron detachment cross-sections at the interaction between negative-ion beams and gas particles in the transport system, and secondary-electron emission factors when negative ions are incident on solid surfaces. These properties of negative-ion beams were investigated experimentally as a function of the ion energy under 50 keV. The single electron detachment cross-sections are almost constant in the other of 10[sup -15] cm[sup 2] in this energy range, but double electron detachment cross-sections increase in proportion to the ion velocity and much smaller than the single one. As for the secondary-electron emission factor, the emission factors for ...

Energy Technology Data Exchange (ETDEWEB)

A method for conditioning electron beams is proposed, making use of the TM{sub 210} mode of microwave cavities, to reduce the axial velocity spread within the beam, in order to enhance gain in resonant electron beam devices, such as the free-electron laser (FEL). Effectively, a conditioner removes the restriction on beam emittance. The conditioner is analyzed using a simple model for beam transport and ideal RF cavities. Analysis of an FEL is employed to evaluate performance with reduced axial velocity spread. Examples of FELs are presented showing the distinct advantage of conditioning.

International Nuclear Information System (INIS)

The most propagated mechanisms of stimulated radiation of electron beam such as Cherenkov one-particle and collective effects, ondulator and magnetic bremsshrahlung radiations, Doppler anomalous effect, Thompson and Raman scattering and radiation are discussed. Relation of spontaneous radiation mechanisms of individual electron and stimulated radiation effects in electron beams has been elucidated, grounds of linear electrodynamics of radiative beam instabilities are stated, and main mechanisms of their nonlinear stabilization are elucidated as well. Various simulated processes in electron beams are considered from the unique point of view using a simple mathematical apparatus and such physical laws as conservation and Newton laws.

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 ...

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...contribution to global warming ...states i think impact of global warming ? and ...contributor to global warming ...

Science.gov (United States)

... electronic feedback system' connected to a Q switch ... The use of acousto-optic (AO) beam steering devices for BMDO (SDI) applications is very ...

International Nuclear Information System (INIS)

There is currently great interest in combining focused ion beam (FIB) and scanning electron microscopy technologies for advanced studies of polymeric materials and biological microstructures, as well as for sophisticated nanoscale fabrication and prototyping. Irradiation of electrically insulating materials with a positive ion beam in high vacuum can lead to the accumulation of charge, causing deflection of the ion beam. The resultant image drift has significant consequences upon the accuracy and quality of FIB milling, imaging and chemical vapour deposition. A method is described for suppressing ion beam drift using a defocused, low-energy primary electron beam, leading to the derivation of a mathematical expression to correlate the ion and electron beam energies and currents with other parameters ...

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.

International Nuclear Information System (INIS)

The description and results of the study on the free-electron laser (FEL) on 100 #mu#m, representing the first line of the FIAN multipurpose radiation complex, are presented. The electron beam with the energy of 6-8 MeV, once accelerated in a racetrack microtron and extracted into the FEL injection tract, is used for exciting this FEL. The system of the electron beam transport, injection and diagnostics are described. Additional works on increasing the beam emittance up to 0.4 A for one energy spread percent are carried out. The obtained electron beam parameters assure generation of the far infrared radiation in the FEL

Energy Technology Data Exchange (ETDEWEB)

This paper describes the effects of motion of beam components (quads, rf cavities and dipoles) on the beam and considers the properties of a compensation system from the perspective of users. The system departs from standard practice in considering active perturbation of the electron beam to verify beam corrections. The effects of local closed orbit perturbations to direct undulator beams at different experimental setups are also considered.

Energy Technology Data Exchange (ETDEWEB)

For over 50 years, electron beams have been an important modality for providing an accurate dose of radiation to superficial cancers and disease and for limiting the dose to underlying normal tissues and structures. This review looks at many of the important contributions of physics and dosimetry to the development and utilization of electron beam therapy, including electron treatment machines, dose specification and calibration, dose measurement, electron transport calculations, treatment and treatment-planning tools, and clinical utilization, including special procedures. Also, future changes in the practice of electron therapy resulting from challenges to its utilization and from potential future technology are discussed. (review)

International Nuclear Information System (INIS)

We discuss polarizing a proton beam in a storage ring, either by selective removal or by spin flip of the stored ions. Prompted by recent, conflicting calculations, we have carried out a measurement of the spin-flip cross section in low-energy electron-proton scattering. The experiment uses the cooling electron beam at COSY as an electron target. The measured cross sections are too small for making spin flip a viable tool in polarizing a stored beam. This invalidates a recent proposal to use co-moving polarized positrons to polarize a stored antiproton beam.

Energy Technology Data Exchange (ETDEWEB)

A simple device is described which is used to determine treatment distance and beam direction in electron therapy employing one collimation. A technique for the production of irregular field templates and localization films is given.

Science.gov (United States)

... predicting potential increases in human mortality due to global warming....

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...global warming situation is more than evaporation around ...background red ? which was the global warming the ...

CERN Document Server

In the beam pipe of the positron damping ring of the Next Linear Collider, electrons will be created by beam interaction with the surrounding vacuum chamber wall and give rise to an electron cloud. Several solutions are possible for avoiding the electron cloud, without changing the bunch structure or the diameter of the vacuum chamber. Some of the currently available solutions for preventing this spurious electron load include reducing residual gas ionization by the beam, minimizing beam photon-induced electron production, and lowering the secondary electron yield (SEY) of the chamber wall. We will report on recent SEY measurements performed at SLAC on TiN coatings and TiZrV non-evaporable getter thin films.

International Nuclear Information System (INIS)

Conversion electron studies of medium-heavy to heavy nuclear mass systems are important where the internal conversion process begins to dominate over gamma-ray emission. The use of a segmented detector array sensitive to conversion electrons has been used to study multiple conversion electron cascades from nuclear transitions. The application of the silicon array for conversion electron detection (SACRED) for in-beam measurements has successfully been implemented. (orig.). With 2 figs.

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.

Energy Technology Data Exchange (ETDEWEB)

Electromagnetic effects excited by intense relativistic electron beams in plasmas are investigated using a two-dimensional particle code. The simulations with dense beams show large magnetic fields excited by the Weibel instability as well as sizeable electromagnetic radiation over a significant range of frequencies. The possible relevance of beam plasma instabilities to the laser acceleration of particles is briefly discussed. 6 refs., 4 figs.

International Nuclear Information System (INIS)

The novolac type phenolic resins were synthesized and electron beam curing was carried out to the prepolymer obtained by the reaction of the phenolic resin and glycidyl meth acrylate in the presence of triethylbenzyl ammonium chloride. When the prepolymer and its mixtures with monomers were irradiated using electron beams at a dose rate of 3 Mrad/sec, the curing were completed at a dose 2.5 and 3 Mrad respectively. The effects of oxygen and that of hydroxyl group in the prepolymer on electron beam curing were also examined. (author).

Energy Technology Data Exchange (ETDEWEB)

Characterization of the electron beam's properties will be a major task after the upgrade of the Los Alamos Free-Electron Laser (FEL) Facility with a photoelectric injector (PEI) and increased acceleration capability to 40 MeV. Adjustments to the previous diagnostics package that address the lower beam emittance, higher energy, and wakefield source reduction issues will be discussed. 6 refs., 8 figs., 1 tab.

Energy Technology Data Exchange (ETDEWEB)

Relativistic electron beams are used for generating high power microwaves. These microwave sources require electron beam generators spanning significant ranges in voltage and impedance. The pulsed power technology used to generate these electron beams is presented. Electron beam generators that produce beams with pulse durations in the 10 ns to 100 ns regime consist of an energy storage section, pulse shaping section, and an electron beam diode. The energy storage section is either a Marx generator or capacitor bank-pulsed transformer. The pulse shaping is done with high-voltage transmission lines. The electron beam diode is usually a cold-cathode, space-charge-limited flow device. For longer pulses (approx.1 ..mu..s) ...

Energy Technology Data Exchange (ETDEWEB)

Methods and apparatus are described for efficient photodetachment and purification of negative ion beams. A method of purifying an ion beam includes: inputting the ion beam into a gas-filled multipole ion guide, the ion beam including a plurality of ions; increasing a laser-ion interaction time by collisional cooling the plurality of ions using the gas-filled multipole ion guide, the plurality of ions including at least one contaminant; and suppressing the at least one contaminant by selectively removing the at least one contaminant from the ion beam by electron photodetaching at least a portion of the at least one contaminant using a laser beam.

Energy Technology Data Exchange (ETDEWEB)

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.

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.

International Nuclear Information System (INIS)

For very low collision energies electron capture from excited hydrogen by multicharged ions is characterized by enormous cross sections, the predicted maximum being comparable to the geometric size of the Rydberg atom. The ion-atom merged-beams technique is being used to study these collisions for the variety of charge states and the wide range of energies (0.1 to 1000 eV/amu) accessible to the apparatus. A neutral D beam containing a Rydberg atom population proportional to 1/n"3 is produced by collisional electron detachment of 8 keV D"- in N_2 gas. An applied electric field results in the range (n=24--11) depending on the strength of the field applied. This beam is then merged with O"3"+ or O"5"+ ion beams at low relative collision velocities where the resultant beam-beam signal of D"+ due to electron loss is dominated ...

Energy Technology Data Exchange (ETDEWEB)

The polarization characteristics of spontaneous radiation from relativistic electrons moving through helical and planar wiggler fields are evaluated for imperfect beam injection. Maximum coherent gain in free-electron laser systems are seen to occur in optical fields having these polarization characteristics rather than those of the wiggler magnets. Coupling coefficients for an electron beam skewed at an angle to the optical mode are presented.

International Nuclear Information System (INIS)

The inelastic scattering of the beam and the residual gas molecules in RHIC could represent one of the limitations on the beam life time and emittance growth. This report covers the dominant central nuclear collisions influence on the beam lifetime and transverse emittance growth. The cross sections for the beam-gas electron radiative captures are an order of magnitude smaller. The capture cross sections include the radiative and non-radiative capture, and the capture from the electron-positron pair creation from the 'vacuum capture'.

Energy Technology Data Exchange (ETDEWEB)

This study investigated dose to bone tissue in electron beam therapy. Measurements were made using films and thermoluminescent dosimeters in a polystyrene phantom containing bone inhomogeneity for 15-MeV, 12-MeV, and 9-MeV electron beams. An increase in dose of approximately 18%, 12%, and 11%, for the three electron energies respectively, relative to the dose in polystyrene, was found for bone material having an electron density (relative to water) of 1.73. Measurements were also made using films for 15- and 9-Mev electrons in a phantom with a mandibular bone and teeth. A dose enhancement in bone of approximately 10% and 7%, respectively, for the two energies was found in the phantom where the electron density of bone was about 1.60. These results suggest that injury to bone is possible in those clinical situations where ...

Energy Technology Data Exchange (ETDEWEB)

The main subject of this thesis is the study of the hardronic final state in deep-inelastic electron-proton scattering. Theexperiment described in this thesis is performed with such a high resolution that the substructure of the proton is probed by the electron beam with a resolution of less than 10{sup -15} cm. (orig./HSI).

Science.gov (United States)

The Global Warming International Center (GWIC) is the international body disseminating information on global warming science and policy, serving both governamental, non-governamental ... ...

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.

Energy Technology Data Exchange (ETDEWEB)

Excessive irradiation due to unexpected leakage was found on a patient receiving electron beam therapy. The cause of this leakage was analyzed and the amount of leakage was measured for different electron beam energies. The highest leakage occurred with a 6 x 6 cm cone using a 12 MeV electron beam. The leakage dose measured along the side of the cone could be as great as 40%. Until the cones are modified or redesigned, it is advised that all patient setups be carefully reviewed to assure that no significant patient areas are in the side scatter region.

Energy Technology Data Exchange (ETDEWEB)

The production of polarized negative ion beams by ''collisional pumping'' is described. Collisional pumping utilizes repeated charge changing collisions in a thick electron-spin-polarized gas or vapor target to form a polarized fast atom beam. The polarized fast atom beam is then partially converted into a polarized negative ion beam in a vapor target. Analysis is presented for a hydrogen beam passing through either a thick polarized H atom target or a thick polarized alkali target. Large polarizations and large currents may be possible.

Energy Technology Data Exchange (ETDEWEB)

The development of high energy (> 150 keV) neutral beams for heating and fueling magnetic fusion devices depends on the ability to produce well-collimated negative ion beams. The double capture charge-exchange technique is a known, scalable method. In order to maximize the overall efficiency of the process and to achieve the desired beam characteristics, it is necessary to examine the optical qualities of the beams as well as the total efficiency of beam production. A combined modeling and experimental study of the angular scattering effects in negative ion formation and loss processes has therefore been undertaken.

International Nuclear Information System (INIS)

New non-collinear schemes are suggested for transverse velocity modulation of electron beams and for the generation of coherent spontaneous radiation by these transversely modulated beams. It is shown that due to the non-collinearity some orders of magnitude enhancement can be achieved for the coherent spontaneous radiation (CSR) power at both the fundamental and harmonic frequencies.

Energy Technology Data Exchange (ETDEWEB)

Recent experiments have explored the use of a free-electron laser (FEL) as a buncher for a microwave two-beam accelerator, and the subsequent driving of a standing-wave rf output cavity. Here the authors present a deeper analysis of the longitudinal dynamics of the electron bunches as they are transported from the end of the FEL and through the output cavity. In particular, the authors examine the effect of the transport region and cavity aperture to filter the bunched portion of the beam.

Energy Technology Data Exchange (ETDEWEB)

This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The main objective of this project was to engineer and procure an electron beamline compatible with the operation of a 1-kW free-electron laser (FEL). Another major task is the physics design of the electron beam line from the end of the wiggler to the electron beam dump. This task is especially difficult because electron beam is expected to have 20 kW of average power and to simultaneously have a 25% energy spread. The project goals were accomplished. The high-power electron design was completed. All of the hardware necessary for high-power operation was designed and procured.

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Energy Technology Data Exchange (ETDEWEB)

There are 13 Electron Beam Ion Sources in operation which produce highly charged ions, up to Th[sup 80+] and Xe[sup 53+]. Most of the sources are used to study these ions under electron impact or when recombining with gaseous or solid targets. That provides an insight into the atomic physics of these highly charged ions and into the physics of the plasma in which such ions can be found. This paper reviews the present knowledge of atomic processes, important in the production of such ions with an EBIS.

International Nuclear Information System (INIS)

A 10.6-micron wavelength free-electron laser (FEL) amplifier has been operated using a 45-MeV, 600-A electron beam from the Advanced Test Accelerator (ATA) and a 15.36-meter long electromagnetic wiggler. The peak small signal power gain was 27 dB(500). Gain guiding was observed to confine the amplified laser beam.

Energy Technology Data Exchange (ETDEWEB)

An array of multiwire proportional counters has been employed to image, in 'real-time', a collimated neutron beam produced at an electron linac facility. Test results are presented, along with a discussion of the advantages of this technique.

UK PubMed Central (United Kingdom)

In view of poor local control rates obtained with standard treatment, intraoperative radiation (IORT) using electrons was combined with external beam irradiation and surgical resection, with or without...Full Text Available

Science.gov (United States)

... of species extinctions in around the world if global warming continues unabated, according to a new study published ... ...

Science.gov (United States)

... of coastal marsh survival in the face of global warming and sea-level rise. It discusses sea-level ... ...

Science.gov (United States)

... different information resources that have to do with global warming and its effects in the state of Alabama. ... ...

International Nuclear Information System (INIS)

The feasibility of a high-energy electron cooling device has been studied through tests on a prototype of the electron device. The apparatus consists of a pulsed ((20-60) keV, 2#mu#s) electron gun, a drift region 1 m long and of a depressed collector for recovering the electron energy. Tests on beam optics and energy recovery have been performed, a high-energy recovery efficiency has been attained. Experimental results are discussed in this paper.

International Nuclear Information System (INIS)

The lifetime of the circulating electron beam in the Naval Research Laboratory modified betatron has been increased by more than 2 orders of magnitude with the addition of strong focusing windings to the device. The injected beam consistently spirals from the injector to the minor axis and is trapped. The #approx#0.5-kA trapped electron ring has been accelerated above 10 MeV from the injection energy of 0.5 to 0.6 MeV. The beam acceleration has been confirmed not only by the x-ray attenuation technique but also with the detection of photoneutrons.

International Nuclear Information System (INIS)

We investigate the chargino production process #gamma##gamma# #-># (W-tilde)"+(W-tilde)"- at high energy #gamma##gamma# colliders in the framework of the minimal supersymmetric standard model (MSSM). Here the high energy #gamma# beams are obtained by the backward Compton scattering of the laser flush by the electron in the basic linear TeV ee colliders. We consider the polarization of the laser photons as well as the electron beams. Appropriate beam polarization could be effective to enhance the cross section to for us extract the signal from the dominant background #gamma##gamma# #-># W"+W"-. (author).

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...global warming is going on we're gonna start to see that ...global warming ...offset the trend of global warming due to greenhouse gases so we gotta get this ...global warming ...the timing and just exactly how global warming will be feedback ...problem with global warming and that the increasing greenhouse gases substantially ...

International Nuclear Information System (INIS)

Coherent Smith-Purcell radiation, emitted from short-bunched electrons passing by a lamellar-type grating of aluminum, has been observed in the millimeter wave region. The energy of the electrons is either 42 MeV when they are accelerated by an L-band linear accelerator or 150 MeV accelerated by an S-band one. The intensity of the radiation is proportional to the square of the beam current. The radiation is linearly polarized, and the electric vector of the radiation is in the plane defined by the observing point and the beam trajectory. The intensity decreases with the beam height, i.e. the distance of the beam from the surface of the grating, in accordance with the modified Bessel function of zeroth order. copyright 1996 American Institute of Physics.

International Nuclear Information System (INIS)

A method using a focused ion beam (FIB) to prepare a silicon amorphous material is presented. The method involves the redeposition of sputtered material generated during the interaction of the Ga"+ ion beam with a silicon substrate material. The shape and dimensions of this amorphous material are self-organized and reproducible. The stability of this amorphous material under electron irradiation was investigated in the transmission electron microscopy (TEM). Electron irradiation can induce recrystallization of the amorphous material, resulting in the lateral and vertical growth, starting at an amorphous-crystalline interface, of polysilicon containing defects.

Energy Technology Data Exchange (ETDEWEB)

The ongoing upgrade of the Los Alamos Free-Electron Laser (FEL) Facility involves the addition of a photoelectric injector (PEI) and acceleration capability to about 40 MeV. The electron-beam and high-speed diagnostics provide key measurements of charge, beam position and profile, divergence emittance, energy (centroid, spread, slew, and extraction efficiency), micropulse duration, and phase stability. Preliminary results on the facility include optical transition radiation interferometer measurements of divergence (1 to 2 mrad), FEL extraction efficiency (0.6 {plus minus} 0.2%), and drive laser phase stability (< 2 ps (rms)). 10 refs.

Energy Technology Data Exchange (ETDEWEB)

Two patients are described in whom sunburn and electron beam radiodermatitis, respectively, were critical determinants in localizing the initial presentation of drug eruptions. In the first instance, a severe sunburn of the back and thighs was followed 7 months later by the appearance of a toxic epidermal necrolysis drug reaction to trimethoprim-sulfamethoxazole in the exact sites of the previous bullous sunburn reaction. In the second patient, a radiodermatitis of the left upper arm due to electron beam therapy for metastatic breast cancer was followed 7 weeks later by a codeine drug reaction confined to the area of the radiodermatitis. In both instances, oral rechallenge with the offending drug reproduced the eruption.

Energy Technology Data Exchange (ETDEWEB)

Recently Emma and Stupakov identified a fatal flaw in a Free Electron Laser (FEL) beam conditioning scheme. They showed that the conditioning is always accompanied by a projected transverse emittance growth that is so large as to make the beam conditioning completely impractical for short wavelength FELs. Furthermore, they provided a general proof along with evidence of computer simulation and reached a conclusion that any beam conditioner, regardless of the method, would suffer from the same constraints and limitations. In this paper, the author proposes an easy surgical removal of the fatal flaw by making a critical yet simple modification to the very scheme analyzed, thus resurrect the beam conditioning for short wavelength FELs. More generally, the also explain why a general search for removing have failed, why the concept and definition of beam ...

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 Science & Technology Center (ISTC)

Development of the Technology and Control of Electron-Beam Welding Procedure and Production of Full Scale Sector of Endcap CMS Hadron Calorimeter. Preparation for Mass Production.

International Nuclear Information System (INIS)

Paper presents conceptual design of free electron laser (FEL) complex for industrial applications. The FEL complex consists of three. FEL oscillators with the optical output spanning the infrared (IR) and ultraviolet (UV) wave-lengths (#lambda# = 0.3...20 #mu#m) and with the average output power 10 - 20 kW. The driving beam for the FELs is produced by a superconducting accelerator. The electron beam is transported to the FELs via three beam lines (125 MeV and 2 x 250 MeV). Peculiar feature of the proposed complex is a high efficiency of the. FEL oscillators, up to 20 %. This becomes possible due to the use of quasi-continuous electron beam and the use of the time-dependent undulator tapering.

Science.gov (United States)

Collective methods of ion acceleration using intense relativistic electron beams (IREB) have stimulated a great deal of interest in the past few years. The main virtue of an IREB collective ion accelerator is the high internal electric field strength. The primary drawback has been an insufficient ion energy gain or inadequate scaleability. An extensive study for generating a high quality electron beam has been done and is presented in Section 2. In Section 3 an intense ion injector study was conducted by the method of computer simulation. The last addition to the proposal was a design for producing a toroidal magnetic field. This field will be needed in a future study of high energy and high current electron beams.

International Nuclear Information System (INIS)

The present article outlines major features of the free electron laser (FEL) and reviews research and development of FEL. Relations among the oscillation frequency, electron beam parameters and wiggler parameters, the physical mechanism of amplification and the physical process of saturation are discussed to identify the difference between FEL and other lasers. The report also outlines techniques for accelerators which are used to generate high-quality, high-energy electron beams required for FEL experiments. Techniques to achieve a short wavelength, high output and high efficiency, and applications of FEL are also discussed. FEL consists of an electron accelerator, wiggler and optical resonator. In FEL, electron beams with a relativistic energy interact resonantly with an electromagnetic field to generate coherent ...

International Nuclear Information System (INIS)

A free-electron laser (FEL) user facility is discussed. The FEL, which will be operated as an oscillator, will be driven by the electron beam of the racetrack microtron (RTM) that is nearing completion. Variation of the electron kinetic energy from 17 MeV to 185 MeV will permit the FEL wavelength to be tuned from 200 nm to 10 #mu#m. Performance will be enhanced by the high brightness, low energy spread, and continuous pulse nature of the RTM electron beam. The authors are designing a new injector to increase the peak current of the RTM. A 3.6-m undulator is under construction, and the 9-m optical cavity is under design. The FEL will emit a continuous train of 3-ps pulses at 66 MHz with an average power of 10--200 W, depending on the wavelength, and a peak power of up to several hundred kW. An experimental area is being prepared with up to five stations for ...

International Nuclear Information System (INIS)

In a seeded high-gain free-electron laser (FEL), where a coherent laser pulse interacts with an ultrarelativistic electron beam, the seed laser pulse can be frequency chirped, and the electron beam can be energy chirped. Besides these two chirps, the FEL interaction introduces an intrinsic frequency chirp in the FEL even if the above-mentioned two chirps are absent. We examine the interplay of these three chirps. The problem is formulated as an initial value problem and solved via a Green function approach. Besides the chirp evolution, we also give analytical expressions for the pulse duration and bandwidth of the FEL, which remains fully longitudinally coherent in the high-gain exponential growth regime. Because the chirps are normally introduced for a final compression of the FEL pulse, some conceptual issues are discussed. We show that to get a short pulse duration, an energy ...

International Nuclear Information System (INIS)

Absolute, cascade-free excitation cross sections in an ion have been measured for the resonance "2S#->#"2P transition in Zn"+ using electron-energy-loss and merged electron-ion beams methods. Measurements were carried out at electron energies of below threshold to 6 times threshold. Comparisons are made with 2-, 5-, and 15-state close-coupling and distorted-wave theories. There is good agreement between experiment and the 15-state close-coupling cross sections over the energy range of the calculations.

Energy Technology Data Exchange (ETDEWEB)

In electron beam therapy, tissue overdose due to electrons backscattered from lead has been profusely studied. To quantify this dose enhancement effect, an electron backscatter factor (EBF) wasdefined as the ratio of dose at the tissue-inhomogeneity interface with and without the scatterer present. The dependence of the EBF on energy at the scatterer surface is not well known for energies lower than 3 MeV which is the most frequent clinical situation. In this work, we have done Monte Carlo calculations with the GEANT code to study EBF in lead at this energy range. The applicability of this code and the developed procedure for dose estimation has been experimentally verified. The dependence of the EBF on the beam energy incident on the scatterer has been studied for different nominal beam energies incident at the phantom's surface. The results show a ...

International Nuclear Information System (INIS)

The proposal made in this paper refers to a free electron laser FEL with small-period electromagnet undulator in SASE regime and a FEL transverse optical klystron in the amplifier regime. The relativistic electron beam source for this FEL is the 7 MeV electron linac of the National Institute for Laser, Plasma and Physics Radiation (NILPRP) in Bucharest. The paper presents the main features of the design and performance of both FELs and discusses the improvements which must be made to the accelerator in order to use it as a free electron source concerning the injection system of electrons and formation of accelerated electron beam. The findings show that this FEL can be employed as a coherent radiation source in the IR range. (author)

Energy Technology Data Exchange (ETDEWEB)

In this note we describe a conceptual design of a part ofthe electron beam delivery system for FERMI@Elettra free electron laser(FEL) located between the end of the linac and the entrance to the FEL.This part includes the emittance diagnostic section, the electron beamswitchyard for two FELs called spreader and matching sections. The designmeets various constrains imposed by the existing and planned buildingboundaries, desire for utilization of existing equipment and demands forvarious diagnostic instruments.

International Nuclear Information System (INIS)

In the convolution/superposition method of photon beam dose calculations, inhomogeneities are usually handled by using some form of scaling involving the relative electron densities of the inhomogeneities. In this paper the accuracy of density scaling as applied to primary electrons generated in photon interactions is examined. Monte Carlo calculations are compared with density scaling calculations for air and cork slab inhomogeneities. For individual primary photon kernels as well as for photon interactions restricted to a thin layer, the results can differ significantly, by up to 50%, between the two calculations. However, for realistic photon beams where interactions occur throughout the whole irradiated volume, the discrepancies are much less severe. The discrepancies for the kernel calculation are attributed to the scattering characteristics of the electrons and the consequent ...

Energy Technology Data Exchange (ETDEWEB)

The effect of electron and ion beam irradiation on the Sisub(LVV) Auger spectra of SiO/sub 2/, Si/sub 3/N/sub 4/ and Si-oxynitride films was measured by the relative intensity of the 92 eV signal, characteristic for the formation of 'free' silicon during irradiation. While in Si-oxynitride the beam effects were almost negligible, some damage was found in Si/sub 3/N/sub 4/, but SiO/sub 2/ appeared to be extremely sensitive for electron and ion beam irradiation. By low energy electron loss spectroscopy of ion bombarded SiO/sub 2/ and Si/sub 3/N/sub 4/ films new electron states due to broken Si-O and Si-N bonds could be determined within the band gap of the insulators. The measured energy losses were interpreted by means of electron energy level schemes of the amorphous films.

International Nuclear Information System (INIS)

The crabbing of an incident photon beam from a laser, and the electron beam with which it interacts at the conversion point, is shown to have the same efficiency as in head-on Compton scattering, but with the advantages of a crossing geometry. The resulting #gamma#-ray beam is also crabbed, which allows for a crossing collision point, while maintaining the luminosity at the same value it would have in a head-on collision.

International Nuclear Information System (INIS)

The crabbing of an incident photon beam from a laser, and the electron beam with which it interacts at the conversion point, is shown to have the same efficiency as in head-on Compton scattering, but with the advantages of a crossing geometry. The resulting #gamma#-ray beam is also crabbed, which allows for a crossing collision point, while maintaining the luminosity at the same value it would have in a head-on collision. ((orig.)).

International Nuclear Information System (INIS)

We present our plans for a Monte-Carlo code simulating all possible combinations of (electromagnetic) interactions between colliding electron, positron, and both high-energy and laser photon beams, based, on the ABEL code for beam-beam interaction. The implementation and first results for the laser-e"- interaction 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.

Energy Technology Data Exchange (ETDEWEB)

An electronically controllable apparatus is described which modulates a continuous wave laser beam so as to produce an output beam consisting of coherent ''pulses'' that are electronically controllable as to both pulse repetition rate and pulse width. The apparatus includes two acoustic devices positioned so that the laser beam passes through them in sequence, and apparatus or for passing sound waves through the devices to frequency shift the laser radiation as well as to diffract it. Each acoustic device such as generates sound waves containing a group of frequencies which result in spaced pulses. The spreading of a laser beam at which emanates from the first acoustic device is countered by the second acoustic device to produce a collimated, coherently pulsed, laser beam.

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 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 ...

International Nuclear Information System (INIS)

The necessity of the electron beam machine characterization via dose measurement is discussed. It includes a measurement of comprehensive dose distribution (at known X and Z axis) for verification of the machine performance. The acquired data were then used to develop the irradiation parameters such as energy, current, distance, conveyor speed, exposure rate and depth inside product to be irradiated. These parameters will be used as a guide for the routine irradiations. (Author)

Energy Technology Data Exchange (ETDEWEB)

A low voltage FEL operating at 130 kV which can be run cw with a continuous electron beam current level up to 12 mA has been constructed for the X-Band microwave range (8-12 GHz). In this poster, we will report on the dependence on time, after the electron beam is switched on, of the growth and competition of those longitudinal modes in the cavity having nett gain.

Energy Technology Data Exchange (ETDEWEB)

Electron beam therapy applied to a lymph node metastasis from a squamous cell carcinoma was followed by the development of histologically and immunologically typical bullous pemphigoid, the lesions being initially strictly confined to the irradiation area. This observation suggests that the bullous pemphigoid antigen may be altered or unmasked by electron beam radiotherapy, leading subsequently to the production of autoantibodies. The disease in this case effectively responded to the administration of tetracycline and niacinamide, a therapeutic regimen described recently.

Energy Technology Data Exchange (ETDEWEB)

Recent development in application of a focused ion beam (FIB) technique to preparation of thin foil specimens for transmission electron microscopy (TEM) observation has been reviewed. Combined technique of FIB/TEM enables one to analyze those microstructures which have been almost impossible or very difficult to analyze so far. (author)

International Nuclear Information System (INIS)

When polarized electrons traverse a region where the laser light is focused their polarization varies even if their energy and direction of motion are not changed. This effect is due to interference of the incoming electron wave and an electron wave scattered at zero angle. Equations are obtained which determine the variation of the electron-density matrix, and their solutions are given. The change in the electron polarization depends not only on the Compton cross section but on the real part of the forward Compton amplitude as well. It should be taken into account, for example, in simulations of the e#->##gamma# conversion for future #gamma##gamma# colliders. (orig.).

International Nuclear Information System (INIS)

Nike is a recently completed multi-kilojoule krypton fluoride (KrF) laser that has been built to study the physics of direct drive inertial confinement fusion. This paper describes in detail both the pulsed power and optical performance of the largest amplifier in the Nike laser, the 60 cm amplifier. This is a double pass, double sided, electron beam-pumped system that amplifies the laser beam from an input of 50 J to an output of up to 5 kJ. It has an optical aperture of 60 cm x 60 cm and a gain length of 200 cm. The two electron beams are 60 cm high x 200 cm wide, have a voltage of 640 kV, a current of 540 kA, and a flat top power pulse duration of 250 ns. A 2 kG magnetic field is used to guide the beams and prevent self-pinching. Each electron beam is produced by its own Marx/pulse forming line system. The amplifier ...

International Nuclear Information System (INIS)

The NRL Long Pulse Induction Linac is being employed in a Free Electron Laser (FEL) experiment. The authors present results of beam transport and focusing experiments as well as measurements of the output radiation generated by various magnetic wigglers. The electron gun of the accelerator presently has a 17-cmdiam. cold cathode which is located in a nearly zero magnetic field (B /SUB z/ less than or equal to 5 G). The gun voltage is flat to within approx. = + or - 5% for 1.5 #mu#sec with this graphite brush cathode. The beam is focused by a series of solenoidal coils as it propagates through the 4-m-long accelerator."2 A solenoidal field which can be varied from 1-10 kG confines the beam in the FEL interaction region. Previous experiments were limited by poor beam transport, focusing, and matching into the relatively large solenoidal field in the FEL region. By ...

International Nuclear Information System (INIS)

Consensus reached in the last few years that fourth generation light source will most likely be a X-ray or a UV coherent source based on single-pass high-gain free electron laser (FEL), such as Self Amplified Spontaneous Emission (SASE), or seeded high-gain harmonic-generation (HGHG) free electron lasers. High-gain (>10"7) required for single-pass FEL puts great constrain on the quality of electron beam, and demands detailed distribution information of electron beam in six-dimension. The typical accelerator system for single-pass FEL consists of a photocathode RF gun injection system, a linac and magnetic bunch compressors, and a long undulator. The major challenges in beam diagnostics for single-pass FEL are to characterize the pico-seconds high-brightness electron beam in six-dimension produced ...

International Nuclear Information System (INIS)

The electron-beam qualities with and without free electron laser (FEL) oscillations were investigated in the compact storage ring NIJI-IV. The peak-electron density in a bunch was suppressed by beam instabilities, so that it was limited to about 1.0 x 10"1"7 m"-"3. The maximum FEL gain estimated for 215 and 300 nm using a well-known one-dimension theory was about 2.8% and 4.6%. The cavity loss at 300 nm was evaluated to be about 2% from the threshold beam current. The bunch length and energy spread with FEL oscillations increased by 1.3 times or more due to bunch heating. The ratio of the FEL gain to a cavity loss estimated from the beam qualities with and without FEL oscillations was almost in accord with the ratio evaluated directly with the measured data of the FEL gain and the cavity loss. (author)

International Nuclear Information System (INIS)

The localized Pt deposition on Si by 30 keV Ga"+ focused ion beam (FIB), 10 keV electron beam (EB) or dual beams (FIB and EB) using precursor gas has been compared by analysis using a 300 keV Be"2"+ microprobe with a beam spot size of 80 nm. The distribution of deposited Pt, Ga from the ion beam itself, and C from the precursor gas was obtained at and nearby the deposited areas by micro-RBS spectra and RBS mapping. All of the beam processed areas showed a uniform Pt distribution at the deposited areas. The amount of Pt atoms increased with the increase in ion or electron dose due to the decomposition of precursor gas. The thickness of Pt layer by EB is considerably less than that by FIB due to the reduced deposition rate. Ga atoms from the center of processed areas partly redeposited at and nearby the FIB processed areas ...

International Nuclear Information System (INIS)

Electron beams as a source of directed energy are under study at the Lawrence Livermore National Laboratory (LLNL). An intense 10-kA, 50-MeV, 50-ns full-width half-maximum, pulsed electron beam is generated by the prototype Advanced Test Accelerator (ATA) at the Laboratory's Site 300. Whenever the electron beam is stopped in materials, intense radiation is generated. Estimates based on available data in the literature show that for materials such as lead, photon radiation (x ray, gamma, bremsstrahlung) levels can be as large as 10"4 roentgens per pulse at 1 m in the zero-degree direction (i.e., the electron-beam direction). Neutrons, which are emitted isotropically, are produced at a level of 10"1"3 n/m"2 per pulse. Depending upon the number of pulses and the shielding geometry, the accumulated dose is potentially lethal to personnel and ...

International Nuclear Information System (INIS)

The main features and advantages of a new low energy nuclear spectroscopic method, the in-beam spectroscopy are described. Results of in-beam spectroscopic experiments performed at the Institute of Nuclear Research (ATOMKI, Debrecen, Hungary) are summarized. Gamma spectra of in-beam produced odd-odd nuclei were measured, gamma-energies were determined. Measurement of gamma-gamma coincidences led to the construction of energy level schemes of the investigated nuclei. Internal conversion electron spectroscopy was used to determine the multipolarities of transitions. A few spectra and level schemes are presented to illustrate the review. Theoretical interpretation of experimental results are briefly summarized. (D.Gy.).

Energy Technology Data Exchange (ETDEWEB)

A high power (200KV), intense current density, low emittance (71mmmrad), high brightness (8x10{sup 10}A/m rad) electron beam was generated in the 10cm long, high-voltage-resistive multi-gap hollow cathode pseudospark chamber filled with 15pa nitrogen and driven by an improved pulse line accelerator. The beam was ejected with the 1mm diameter, the 2.2KA beam current, and the 400ns pulse length, and could propagated 20cm in the drift tube. At a distance of 5cm from the anode it penetrated consecutively an acid-sensitive discoloring film and a 0.05mm-thick copper foil both stuck closely, left 0.6mm and 0.3mm holes on them, respectively. That 10 shots on an acid-sensitive film produced a hole of 1.6mm at 7cm downstream of anode showed its good repeatability. After 60 shots the pseudospark discharge chamber was disassembled and observed that almost no destructive damage traces left on the surfaces of its ...

CERN Document Server

Aims: The production of saturated organic molecules in hot cores and corinos is not well understood. The standard approach is to assume that, as temperatures heat up during star formation, methanol and other species evaporate from grain surfaces and undergo a warm gas-phase chemistry at 100 K or greater to produce species such as methyl formate, dimethyl ether, and others. But a series of laboratory results shows that protonated ions, typical precursors to final products in ion-molecule schemes, tend to fragment upon dissociative recombination with electrons rather than just ejecting a hydrogen atom. Moreover, the specific proposed reaction to produce protonated methyl formate is now known not to occur at all. Methods: We utilize a gas-grain chemical network to probe the chemistry of the relatively ignored stage of hot core evolution during which the protostar switches on and the temperature of the surrounding gas and dust rises from 10 K to ...

International Nuclear Information System (INIS)

Purpose: A retrospective analysis was undertaken to determine the indications for, the efficacy of, and the long-term complications of two courses of total skin electron beam therapy for mycosis fungoides. Methods and Materials: A retrospective analysis of 15 patients with the pathologic diagnosis of mycosis fungoides treated in the Department of Radiation Oncology at Stanford University Medical Center between 1968 and 1990 was performed. All patients received two courses of high-dose electron beam therapy to the skin. The mean dose for the total skin treatment for the first course was 32.6 Gy and 23.4 Gy for the second course of treatment. Results: Following the first course of total skin electron beam therapy, 11 of 15 had a complete response, with a mean duration of 11.6 months. All patients received adjuvant therapies between the first and second courses of ...

International Nuclear Information System (INIS)

In the framework of the Low Emittance Gun (LEG) project, high gradient acceleration of a low emittance electron beam will be necessary. In order to achieve this acceleration, a -500 kV, 250 ns FWHM, pulse will be applied between two electrodes. Those electrodes should sustain the pulsed field without arcing, must not outgas and must not emit electrons. Ion back bombardment, and dark current will be damaging to the electron source as well as for the low emittance beam. Electrodes of commercially available OFE copper, aluminium, stainless steel (SS), titanium and molybdenum were tested, following different procedures including plasma glow discharge cleaning.

ScienceCinema

...march and my hope is that global warming because i believe it is real and i believe we have ...global warming ...system of energy which does not produce the global warming guess they should be here ? ...

International Nuclear Information System (INIS)

The principle and history of free-electron laser (FEL), first evidenced in 1977, the relationship between FEL wavelength and output power, the high-power FEL driven by the superconducting linac, the X-ray FEL by the linac, and the medical use are described. FEL is the vacuum oscillator tube and essentially composed from the high-energy linac, undulator and light-resonator. It utilizes free electrons in the vacuum to generate the beam with wavelength ranging from microwave to gamma ray. The first high-power FEL developed in Japanese Atomic Energy Research Institute (JAERI) is based on the development of superconducting linac for oscillating the highest power beam. In the medical field, applications to excise brain tumors (in US) and to reconstruct experimentally blood vessels in the pig heart (in Gunma University) by lasing and laser coagulator are in progress with examinations to remove intra-vascular ...

Energy Technology Data Exchange (ETDEWEB)

During the previous 9 months the major part of the Fusion-FEM has been constructed. The 2 MV Insulated Core Transformer, the electron gun, the accelerator, the focusing lenses and the undulator have been tested on-site. In the present - temporary - set-up, the electron beam line consists of a 12 A, 80 keV thermionic electron gun, a 2 MeV dc accelerator, beam transport optics, the undulator and a collector. The gun is mounted in the high voltage terminal, which is now at -2 MV, and the undulator and mm-wave system am at ground potential outside the SF{sub 6}-filled pressure tank. This so-called inverse set-up allows easy access to the larger part of the beam line, the undulator and the mm-wave system, which is important in the conditioning phase. The decelerator and depressed collector am not yet installed. The design of the electron ...

International Nuclear Information System (INIS)

Focused ion beam (FIB) milling is a powerful and versatile tool for the maskless fabrication of structures and devices at micro- and nanometer scales. The approach is based on the milling and deposition capabilities of a focused ion beam, where the latter is achieved by ion-beam-assisted decomposition of a metalorganic gas precursor of the specific material that has to be deposited. The combination of FIB and scanning electron microscopy in the same unit (so-called dual-beam unit) further expands the capabilities of the approach by the possibility of performing electron-beam-assisted deposition and inspection. Permalloy nanowires with electrical contacts patterned by FIB-Pt deposition were prepared in the dual-beam unit. Various types of notches to pin magnetic domain walls were additionally fabricated by means of FIB. The fabrication ...

ScienceCinema

...policy issues global warming global climate change ? there's a famous hockey ...global warming the greatest hopes for betray them and kind of forgotten ...

International Nuclear Information System (INIS)

The authors report on observations of plasma wave turbulence generated during electron beam injections, spacecraft potential variations, and neutral gas emissions of the CHARGE 2 sounding rocket experiment. The payload was flown in a mother/daughter configuration, with the two sub-payloads electrically connected by an insulated, conducting tether. While tethered, the two platforms were separated, drifting apart in a direction perpendicular to both the magnetic field and to the spacecraft velocity, reaching a maximum distance of 426 m at the end of the flight. The mother carried a high-voltage (HV) system (0-460 V), biasing the mother negative relative to the daughter. The operation of the HV bias system simulated the motional emf induced in larger orbiting space structures like the Tethered Satellite System 1 (TSS 1) space shuttle mission scheduled for the spring of 1992. In addition, the mother carried an electron ...

International Nuclear Information System (INIS)

We report on the first measurements of the z-dependent evolution of electron-beam microbunching as revealed through coherent transition radiation (CTR) measurements in a visible self-amplified spontaneous emission free-electron laser experiment. The increase in microbunching was detected by tracking the growth of the visible CTR signals as generated from insertable metal mirrors/foils after each of the last three undulators. The same optical imaging diagnostics that were used to track the z-dependent intensity of the undulator radiation (UR) were also used to track the electron beam/CTR information. Angular distribution, beam size, and intensity data were obtained after each of the last three undulators in the five-undulator series, and spectral information was obtained after the last undulator. The exponential growth rate of the CTR was found to be very similar to that of the UR ...

Science.gov (United States)

Intrinsic spherical aberrations of electron lenses have been the major resolution limiting factor in electron microscopes for several decades. While effective correctors have recently been implemented, an alternative to correct these aberrations is to circumvent them by scaling down lens dimensions by several orders of magnitude. We have fabricated electrostatic lenses exhibiting one micrometer diameter apertures and evaluated their beam forming properties against predictions from numerical ray tracing simulations. It turns out that it is routinely possible to shape a paraxial low-energy electron beam by such micron-sized lenses. Beam profiles have been measured both at a distant detector as well as in a plane close to the lens. It is shown that the lens can form a parallel beam extending no more than 800 nm from the optical axes at a ...

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.

Energy Technology Data Exchange (ETDEWEB)

Measurements of the double-electron-capture process in which a positive ion of iodine becomes a negative ion in a single collision with a magnesium atom are reported between 20 and 90 keV. The cross section is comparable to that for the rare gases and not as large as might be expected from a two-valence-electron atom. This process is probably insignificant in the production of negative ion beams using a magnesium-vapor target.

International Nuclear Information System (INIS)

The invention refers a procedure of radiation dose control in irradiated tissues during electron-beam therapy. It aims at meeting the planned radiation dose for diseased tissues and taking care of the healthy ones. Therefore, the dose distribution required is determined before irradiation in consideration of such factors as energy-dependence of detector sensitivity, self-absorption within the tissue, and relative biological effectiveness. Furthermore, the expected intensity distribution of secondary quantum radiation excited in the irradiated tissue is calculated. A radiation detector for local resolution is used for registration. During irradiation the calculated intensity distribution is compared with the measured one. The invention is applicable in radiation therapy with monoenergetic electron beams.

International Nuclear Information System (INIS)

Polyester WPC (wood-polymer composite) systems are one of the promising materials for multiple uses increasing the mechanical properties, provided that their dimensional stability can be improved. Possibility was pursued for the improvement in the dimensional stability of the polyester WPC systems prepared by electron beam irradiation. The impregnation of the mixture of polyester and monomer into both oven-dried beech veneers and preswollen wood was followed by mutual irradiation process. Polymerization was carried out at total dosage of 6 Mrad to the respective surfaces of samples by an electron beam accelerator, and the reaction was completed by heating at 80 deg C for 24 hr. The dimensions of the samples were measured primarily in the tangential direction, and their dynamic modulus and loss modulus were measured by a Rheovibron DDV-2 and the vibrating reed method. The results and the discussion are ...

International Nuclear Information System (INIS)

A previous analysis aimed at underlining the importance of the relativistic electron beam quality for the performances of a Free Electron Laser (FEL) is continued in the paper by the study of the influence of the undulator field (wiggler) parameters and of the optical beam (and/or optical cavity) quality on the operation of a FEL. The importance of parameters such as K, #lambda#_u, g of the undulator, F, P_L, #nu#_c of the optical beam, and L, L_o_p_t and L_c_r of the optical cavity for the characteristics of the input radiation as P_o_u_t, G_o_p_t, and #eta# are analyzed and some relations between these parameters that will give the possibility to estimate the corresponding values are given. Some proposal for the design of a compact FEL in IR-spectral region, with #lambda# #approx# 230 #mu#m are given. (Author).

Energy Technology Data Exchange (ETDEWEB)

One of the main challenges for a high energy {gamma}{gamma} collider is the high repetition rate required for the laser-electron-beam collisions to convert into high energy gamma beams. State-of-the-art, high power lasers have a much lower repetition rate than that of the electron pulses. It is therefore highly desirable that the same laser pulse can be reused. As an example, for NLC where beams collide at 120 Hz, within each collision cycle there are 90 electron bunches separated by 1.4 ns between successive bunches. We show, by invoking a recently invented laser optical box, that the laser pulses can be reused for the entire train of bunches within each collision cycle. ((orig.)).

International Nuclear Information System (INIS)

An electron moving over the surface of a diffraction grating will transfer a part of its kinetic energy to radiation via a velocity synchronous coupling with a slow space harmonic component of the field. Since the phase velocity of a slow space harmonic is less than the speed of light, the slow components decay exponentially, or evanesce, with distance above the grating and the evanescence scale is determined by the product of the relative velocity, #beta#, the relative energy, #gamma#, and the wavelength #lambda#. Thus, in the relativistic regime, good electron - grating coupling can be maintained at beam heights that are greater than the emitted wavelength. In order to explore this regime a series of experiments have been carried out with moderately energetic beams and an experiment with the 70-MeV beam at the Accelerator Test Facility is in the planning stage. The work has two ...

Energy Technology Data Exchange (ETDEWEB)

The Front End Enclosure (FEE) of the Linac Coherent Light Source (LCLS) is a shielding housing located between the electron dump area and the first experimental hutch. The upstream part of the FEE hosts the commissioning diagnostics for the FEL beam. In the downstream part of the FEE, two sets of grazing incidence mirror and several collimators are used to direct the beam to one of the experimental stations and reduce the bremsstrahlung background and the hard component of the spontaneous radiation spectrum. This paper addresses the beam loss assumptions and radiation sources entering the FEE used for the design of the FEE shielding using the Monte-Carlo code FLUKA. The beam containment system prevents abnormal levels of radiations inside the FEE and ensures that the beam remains in its intended path is also described.

International Nuclear Information System (INIS)

We explore a novel phenomenon of focused ion beam (FIB) induced bending of carbon nanopillars or cantilever structures. The bending occurs towards the ion beam during scanning. The explanation of this bending has been sought on the basis of a model which considers temperature rise and gradients caused by the impinging ion beam. The process is controllable and reversible, which makes it highly suitable for in situ manipulation to make desired 3D shapes by the piecewise bending of the nanopillars and cantilever structures during their fabrication using electron beam or FIB chemical vapor deposition (EB-CVD or FIB-CVD). Its usefulness in the fabrication of nanosize mechanical components has been demonstrated by making a branch structure from a single cantilever.

Energy Technology Data Exchange (ETDEWEB)

The Holifield Radioactive Ion Beam Facility (HRIBF) now under construction at the Oak Ridge National Laboratory will use the 25-MV tandem accelerator for the acceleration of radioactive ion beams to energies appropriate for research in nuclear physics; negative ion beams are, therefore, required for injection into the tandem accelerator. Because charge exchange is an efficient means for converting initially positive ion beams to negative ion beams, both positive and negative ion sources are viable options for use at the facility; the choice of the type of ion source will depend on the overall efficiency for generating the radioactive species of interest. A high-temperature version of the CERN-ISOLDE positive ion source has been selected and a modified version of the source designed and fabricated for initial use at the HRIBF because of its low emittance, relatively high ionization ...

Energy Technology Data Exchange (ETDEWEB)

In the previous paper, we have derived a dispersion relation for the free electron laser (FEL) gain in the exponential regime taking account the diffraction and electron`s betatron oscillation. Here, we compare the growth rates obtained by solving the dispersion relation with those obtained by simulation calculation for the waterbag and the Gaussian models for the electron`s transverse phase space distribution. The agreement is found to be good except for the limiting case where the Rayleigh length is much longer than the gain length (1-D limit). We also generalize the analysis to the case where the electron beam cross section is elliptical as is usually the case in storage rings, and derive the first-order dispersion relation.

International Nuclear Information System (INIS)

Free-electron laser (FEL) amplifiers have demonstrated high efficiencies and high output power at microwave wavelengths. However, measurements and simulations have indicated that the present level of phase stability for these devices is not sufficient for driving linear accelerators. Fluctuations in the diode voltage, which is needed to accelerate the electron beam, are the largest cause of the shifts in the phase of the output power. Pulse-power technology cannot keep the voltage fluctuations less than 1/4%. However, we have found a scheme that will make the output phase much less sensitive to these fluctuations by exploiting the traveling wave nature of the FEL interaction. In this paper we study the phase stability issue by analyzing the dispersion relation for an axial FEL, in which the rf field is transversely wiggled and the electron trajectories are purely longitudinal. The advantage of using the ...

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 ...

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 ...

Energy Technology Data Exchange (ETDEWEB)

Two types of switched electrode electronics beam position monitors are in use at Jefferson Lab. Together they provide accurate beam position to the control system for beam intensities between 50 nA and 2 mA. One version, called the linac style, has a switching frequency of 125 kHz. The other, called the transport type, has a switching frequency of 7 kHz. The basic system provides information to the control system at a 1 Hz update rate. The systems are regularly used to measure the AC component of beam position and energy as well as suppress this motion as part of a fast feedback system. Position data produced by the system are also acquired on an event by event basis as part of the nuclear physics program in two of the experimental halls. This paper will focus on the AC characteristics of the system. These characteristics are affected by analog filter frequencies and a time delay ...

Energy Technology Data Exchange (ETDEWEB)

High energy radiation was studied as a means for destroying hazardous organic chemical wastes. Tests were conducted at bench scale with a {sup 60}Co source, and at full scale (387 l/min) with a 1.5 MV electron beam source. Bench scale tests for both benzene and phenol included 32 permutations of water quality factors. For some water qualities, as much as 99.99% of benzene or 90% of phenol were removed by 775 krads of {sup 60}Co irradiation. Full scale testing for destruction of benzene in a simulated waste-water mix showed loss of 97% of benzene following an 800 krad dose and 88% following a 500 krad dose. At these loss rates, approximately 5 Mrad of electron beam irradiation is required to reduce concentrations from 100 g/l to drinking water quality (5 {mu}g/l). Since many waste streams are also inhabited by bacterial populations which may affect filtering operations, the effect of irradiation on those ...

CERN Document Server

The simple device for scanning image is described. It has much in common with usual TV camera, with an electron beam replaced by an optical one. After the general description of the device, we present a simple experimental illustration.

Energy Technology Data Exchange (ETDEWEB)

A Bragg waveguide consisting of multiple dielectric layers with alternating index of refraction becomes an excellent option to form electron accelerating structure powered by high power laser sources. It provides confinement of a synchronous speed-of-light mode with extremely low loss. However, laser field can not be coupled into the structure collinearly with the electron beam. There are three requirements in designing input coupler for a Bragg electron accelerator: side-coupling, selective mode excitation, and high coupling efficiency. We present a side coupling scheme using a distributed grating-assisted coupler to inject the laser power into the waveguide. Side coupling is achieved by a grating with a period on the order of an optical wavelength. The phase matching condition results in resonance coupling thus providing selective mode excitation capability. The coupling efficiency is limited by ...

International Nuclear Information System (INIS)

Electron beam therapy of lesions such as cutaneous metastatic carcinoma and reticulum cell sarcoma is performed via multiple portals for a wide irradiation field. However, the dose distribution in border areas is generally uneven, resulting in hot and cold dose areas depending on the intervals of the portals. We performed electron irradiation by the pendulum technique, especially on curved areas, and evaluated the technique in various respects. Pendulum electron beam irradiation is indicated when the length of the cone must be reduced in order to deliver the target volume near the skin surface as well as to avoid the occurrence of hot spots deep in the body. We prepared a 15cm rotating cone by cutting a 30cm fixed irradiation cone. The modification posed no disadvantages in terms of extent and flatness of the beam, or stability during rotation. After determining ...

Science.gov (United States)

... relaxation and a sense of well-being. Warm whirlpool baths, molten paraffin application to the hands and ...

Science.gov (United States)

This fact sheet summarizes the potential impact of climate change as it relates to public health in California....

ScienceCinema

...of the and global warming signal so ...

ScienceCinema

...carbon dioxide in the atmosphere contributes to global warming anything that could ...

Energy Technology Data Exchange (ETDEWEB)

A design of a compact free-electron laser (FEL), generating ultra-fast, high-peak flux, XUV pulses is presented. The FEL is driven by ahigh-current, 0.5 GeV electron beam from the Lawrence Berkeley National Laboratory (LBNL) laser-plasma accelerator, whose active acceleration length is only a few centimeters. The proposed ultra-fast source (~;;10 fs) would be intrinsically temporally synchronized to the drive laser pulse, enabling pump-probe studies in ultra-fast science. Owing to the high current (>10 kA) of the laser-plasma-accelerated electron beams, saturated output fluxes are potentially greater than 10^13 photons/pulse. Devices based both on self-amplified spontaneous emission and high-harmonic generated input seeds, to reduce undulator length and fluctuations, are considered.

International Nuclear Information System (INIS)

A variable-dispersion electron spectrometer is being installed for use by the Stanford Superconducting Accelerator in conjunction with its Free Electron Laser program. The system has been designed to operate with electron beam energies from 20 MeV to 200 MeV, with a maximum energy resolution of 0.01% FWHM. The maximum energy acceptance is approximately #+-# 5%, as determined by the bending magnet aperture. Resolution is controlled by adjusting the focal conditions at the entrance to a 90 degree bending magnet, while the dispersion is controlled by changing the magnitude and polarity of the field in a quadrupole magnet which immediately follows the bending magnet. 4 refs., 5 figs.

Energy Technology Data Exchange (ETDEWEB)

Electron energy loss (EEL) spectroscopy and high angle annular dark field (HAADF) imaging in aberration-corrected electron microscopes are powerful techniques to determine the chemical composition and structure of materials at atomic resolution. We have implemented Smart Acquisition, a flexible system of scanning transmission electron microsocpy (STEM) beam position control and EELS collection, on two aberration-corrected dedicated cold field emission gun (FEG) STEMs located at SuperSTEM, Daresbury Laboratory. This allows the collection of EEL spectra from spatially defined areas with a much lower electron dose possible than existing techniques such as spectrum imaging.

International Nuclear Information System (INIS)

The term Smith-Purcell free electron laser can be employed generally to describe any coherent radiation source in which a diffraction grating is used to couple an electron beam with the electromagnetic field. To date, most practical developments of this concept have focused on devices which operate in the millimeter spectral regime. In this paper construction of a Smith-Purcell free-electron laser operating in the far-infrared (FIR) region using a novel resonator cavity design and the electron beam from a low energy (0.5-5 MeV) radio-frequency accelerator will be discussed. A tunable source in this region would have many applications and since the beam energy is low, the small size and low overall cost of such a device would make it a laboratory instrument. Current projects which are progressing towards developing a FIR source are the ...

International Nuclear Information System (INIS)

Smith-Purcell (S-P) radiation is produced when electrons graze the surface of a grating. Calculations based on the theory of diffraction radiation show that, given severe restrictions on e"--beam quality, S-P radiation is highly efficient. Efficient S-P x-ray generation requires relativistic e"- beams having a transverse momentum and dimension whose product approaches the Heisenberg uncertainty limit.

CERN Document Server

Lead tungstate crystals doped with small fractions of praesodynium or molybdenum have been tested in beams of high-energy electrons. The goal of these tests was to study the effects of such dopants on the capability to separate the signal components deriving from the Cherenkov and scintillation light generated by the beam particles. These studies were carried out in view of the possible application of such crystals in dual-readout calorimeters.

Energy Technology Data Exchange (ETDEWEB)

The working group reviewed the main difficulties foreseen in doing physics at a gamma-gamma collider. They discussed the requirements for the detector, calculated some of the signal and background rates, compared methods of measuring luminosity, looked at how to get the laser beams in, investigated ways of sweeping aside the electrons and considered ways of disposing of the used beams. No overwhelming obstacles were found but important questions still need to be answered. ((orig.)).

International Nuclear Information System (INIS)

A family of industrial irradiators is being developed by AECL to cover an electron-beam energy range from 5 to 18 MeV at beam powers between 20 and 250 kW. The IMPELA family of irradiators is designed for push button, reliable operation. The major irradiator components are modular, allowing for later upgrades to meet increased demands in either electron or X-ray mode. Interface between the control system, irradiator availability and dose quality assurance is in conformance with the most demanding specifications. The IMPELA irradiators use a klystron-driven, standing-wave, L-band accelerator structure with direct injection from a rugged, triode electron gun. Direct control of the accelerating field during the beam pulse ensures constant output beam energy, independent of beam power. The first member of the family, the IMPELA 10/50 (10 MeV, 50 ...

International Nuclear Information System (INIS)

Structural changes of a Ni-P amorphous alloy under focused-ion-beam (FIB) irradiation have been examined using transmission electron microscopy. On the irradiated plane, the formation of crystallographically orientated nanosized crystals (NCs), with the particle size of approximately 10 nm, was observed. A series of electron diffraction analyses have revealed that NCs have a face-centered-cubic (fcc) structure and the following orientation relationships between the NCs and the FIB direction were found. These are, irradiated plane//(111)_f_c_c and FIB direction//_f_c_c.

International Nuclear Information System (INIS)

Mass spectrometry was instrumental in the discovery of the fullerenes and the characterization of their special structure (truncated icosahedron). High resolution and high sensitivity mass spectrometry in combination with a crossed molecular beam/electron beam ion source is used here to study a further, very unique property of singly and multiply charged fullerene ions (up to Z=7), i.e. their strong resilience towards decomposition via sequential C_2 evaporation and via Coulomb explosion, respectively. (author).

International Nuclear Information System (INIS)

Electron beam therapy has often been used for radiation therapy of carcinomas of the buccal mucosa, though side effects, including stomatitis and dermatitis, are known to exist. We experimented using the additional back scatter and transit with the phantom under a lead plate within the irradiation field, in order to better focus the dose on the target volume moreover, we fabricated a mouthpiece fitted with a lead plate shaped to the target volume, and with respect to the influence of the mouthpiece on stomatitis and dermatitis, obtained good clinical results. (author).

Energy Technology Data Exchange (ETDEWEB)

Comparison of dosimetry measured in a noncylindrical Rando-Alderson phantom by two-field, four-field, and six-field total-skin electron-beam therapy (TSEBT) techniques with our dual-field rotational (DFR) technique reveals a superior dosimetry for the latter. Our technique of dual-field rotational DFR-TSEBT is described in detail, and its advantages and indications for the primary management of cutaneous T-cell lymphoma (CTCL) and Kaposi's sarcoma (KS) are discussed.

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 ...

International Nuclear Information System (INIS)

The KAERI compact far-infrared (FIR) free-electron laser (FEL) has been operated successfully in the wavelength range of 97-150 #mu#m. It is the first demonstration of FEL lasing by using a magnetron-based classical microtron. We developed a high precision undulator consisting of 80 periods, with each period being 25 mm. The field strength of the undulator can be changed from 4.5 to 6.8 kG with an amplitude deviation of only 0.05% in r.m.s value. The kinetic energy of the electron beam is 6.5 MeV. The average current and pulse duration of the electron beam macropulses are 45 mA and 5.5 #mu#s, respectively. The measured power of the FEL with the electron beam parameters was more than 50 W for a FIR macropulse having a duration of 4 #mu#s. The spectral width of the FEL was measured to be 0.5% of the central wavelength. The FEL system, aside ...

Energy Technology Data Exchange (ETDEWEB)

Propagation of an intense charged particle beam pulse through a background plasma is a common problem in astrophysics and plasma applications. The plasma can effectively neutralize the charge and current of the beam pulse, and thus provides a convenient medium for beam transport. The application of a small solenoidal magnetic field can drastically change the self-magnetic and self- electric fields of the beam pulse, thus allowing effective control of the beam transport through the background plasma. An analytic model is developed to describe the self-magnetic field of a finite- length ion beam pulse propagating in a cold background plasma in a solenoidal magnetic field. The analytic studies show that the solenoidal magnetic field starts to infuence the self-electric and self-magnetic fields when ?ce > ?pe?b, where ?ce = e?/mec is the ...

Energy Technology Data Exchange (ETDEWEB)

A technique capable of measuring the electron energy fluence spectra in a scattering medium was designed. These measurements were performed by setting a bremsstrahlung conversion target on the surface of a phantom, at an intermediate depth, and at a depth equal to electron mean range. The bremsstrahlung produced by the deceleration of electrons in the target was passed through an air channel in the phantom and passed forward by a pinhole collimator into a Na(Tl) detector. The measured pulse height data were unfolded to correct for the distortion of the spectrometer system by using the FORIST unfolding code. The unfolded bremsstrahlung spectra represent the electron energy fluence spectra convolution with the bremsstrahlung produced in the target. To generate the electron energy fluence spectra, the unfolded bremsstrahlung spectra were deconvoluted by using the MAZE2 unfolding code. ...

International Nuclear Information System (INIS)

Stimulated bremsstrahlung in an undulating electric field in the lasing beam direction (electric wiggler) was shown to be possible from the quantum- mechanical viewpoint. Herein, this possibility is scrutinized from the viewpoint of classical electrodynamics. It is found that if stimulated bremsstrahlung in a transverse undulating magnetic field (magnetic wiggler) occurs, stimulated bremsstrahlung in the electric wiggler must also occur. We further show that a free electron laser (FEL) using a magnetic wiggler to provide a catalyzer field for stimulated bremsstrahlung cannot serve as a practical FEL operating in the soft x-ray region from both theoretical and experimental viewpoints. On the other hand, the authors demonstrate that the FEL using a traveling wake field in a two-beam elliptical pill-box cavity is well suited as a source of coherent radiation in the soft x-ray region.

Energy Technology Data Exchange (ETDEWEB)

A unique beam of pulsed electrons has been developed using the 19-MeV, 700-kA Hermes-III accelerator. The extended planar-anode diode is used to extract at large radius an annular electron beam from the accelerator and inject the resulting beam at small angle into a low-pressure gas cell, where the beam is rapidly charge neutralized and almost current neutralized. Under these conditions, the beam propagates nearly ballistically to a focus downstream of injection, where objects can be placed for irradiation and study. For a focal length of 78 cm, measurements with a segmented calorimeter show that this configuration can deliver an energy deposition of 200 J/g [20 Mrad] over a useful area of 70 cm{sup 2} and a 4-cm depth in graphite in 25 ns. Increasing the injection angle by reducing the AK gap permits higher doses over smaller areas to be ...

International Nuclear Information System (INIS)

Localized beam-processed areas using chemical reactions induced by a 30 keV Ga"+ focused ion beam (FIB) with and without I_2 (etching) and (CH_3)_3CH_3C_5H_5Pt gases (Pt deposition) have been analyzed using a 300 keV Be"2"+ microprobe with a beam spot size of 50-80 nm. The analyzed results have been compared with energy dispersive X-ray (EDX) analysis using an electron beam. The EDX analysis only indicated incorporated impurities at high fluence such as Ga, Pt and C, while microprobe RBS analysis could detect residual iodine with low concentration which couldn't be detected by EDS analysis because of the lower sensitivity of the EDX analysis for heavy atoms.

International Nuclear Information System (INIS)

Nanometre-sized materials, like nanowires, nanoparticles or nanobelts, are gaining huge interest as building blocks of modern electronic nanodevices. Their fabrication feasibility has been demonstrated in the last years, and different routes are already well established in order to synthesize these materials. However, the assessment of their electrical properties is still a challenging issue, due to the difficulty to perform a precise nanolithography process allowing the access to such small structures. The fabrication of metallic contacts with precision in the nanometre range is necessary, as well as achieving a flexible system that allows to contact individual structures. Such a system could be a dual-beam Focused Ion Beam instrument, which combines Scanning Electron Microscopy (SEM) and Focused Ion Beam (FIB) in one machine, able to assist deposition of materials with nanometre ...

Science.gov (United States)

The ratio of the proton's electric to magnetic form factor, G{sub E}/G{sub M}, can be extracted in elastic electron-proton scattering by measuring cross sections, beam-target asymmetry, or recoil polarization. Separate determinations of G{sub E}/G{sub M} by cross sections and recoil polarization observables disagree for Q{sup 2}>1 (GeV/c){sup 2}. Measurement by a third technique might uncover an unknown systematic error in either of the previous measurements. The beam-target asymmetry has been measured for elastic electron-proton scattering at Q{sup 2} = 1.51 (GeV/c){sup 2} for target spin orientation aligned perpendicular to the beam momentum direction. This is the largest Q{sup 2} at which G{sub E}/G{sub M} has been determined by a beam-target asymmetry experiment. The result, {mu}G{sub E}/G{sub M}=0.884{+-}0.027{+-}0.029, is compared to previous ...

International Nuclear Information System (INIS)

Electron probe microanalysis (EPMA) offers high sensitivity and high accuracy in quantitative measurements of chemical compositions and mass coverages. Owing to the low detection limits of the wavelength-dispersive technique, monolayers with mass coverages of about 0.05 pg cm z can be detected. Assuming a density of 5 g cm--3 this corresponds to a thickness of 0.1 nm. With these advantages in mind, EPMA was extended to depth profile analysis in the sub-micron range using a surface removal technique. The present paper shows how depth profile analysis can be improved by combining EPMA and the focused ion beam (FIB) technique. The focused ion beam system uses a Ga+ ion beam. The ion beam allows the milling of defined geometries on the nanometer scale, so that very shallow bevels with exactly defined angles in relation to the surface can be obtained. Low surface damage is expected due ...

Energy Technology Data Exchange (ETDEWEB)

Free-electron-laser (FEL) oscillators require a train of high-brightness bunches. Conventional subharmonic bunchers are currently used with rf linacs to generate pulse trains, but the resulting dilution of the transverse phase space and lower beam brightness are unacceptable for high-performance FELs. Recent developments suggest that photoemitters of high quantum efficiency combined with rapid acceleration can produce pulse trains of higher brightness than has been achieved before.

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 be placed either 16 or ...

International Nuclear Information System (INIS)

Among the investigations conducted on the space shuttle flight STS 3 March 1982 was an experiment in which a 1-keV, 100-mA electron gun was pulsed at 3.25 and 4.87 kHz. The resultant waves were measured with a broadband plasma wave receiver. At the time of flight the experimental setup was unique in that the electron beam was square wave modulated and that the shuttle offered relatively long times for in situ measurements of the ionospheric plasma response to the VLF pulsing sequences. In addition to electromagnetic response at the pulsing frequencies the waves exhibited various spectral harmonics as well as the unexpected occurrence of satellite lines around those harmonics. Both phenomena occurred with a variety of different characteristics for different pulsing sequences.

Energy Technology Data Exchange (ETDEWEB)

Time-resolved characterizations of electron beams using optical transition radiation (OTR) as a prompt conversion mechanism have recently been extended on the Los Alamos Free-electron Laser (FEL) facility 40-MeV linac. Two key timescales for rf-linac driven FELs are the micropulse (10 ps) and the macropulse (5 {mu}s to 1 ms). In the past we have used gated, intensified cameras to select a single or few micropulses (25 to 400 ns gate width) out of the pulse train to evaluate submacropulse effects. Recently, we have obtained some of the first measurements of micropulse bunch length (7 to 10 ps) and submacropulse spatial position and profile using OTR and a Hamamatsu streak camera. Additionally, micropulse elongation effects and head-to-tail transverse kicks are reported as a function of charge.

Energy Technology Data Exchange (ETDEWEB)

The technical complexity of intraoperative radiotherapy (IORT) requires modification of the standard physical and dosimetric methods used in external electron beam therapy. At the National Cancer Institute, a number of technical innovations have been integrated into ongoing clinical studies of IORT. These include: (1) an electron beam applicator system that is significantly different from other IORT systems and includes customized squircle applicators; (2) peripheral dose shields; (3) a modified surgical table replacing the standard radiation treatment couch; and (4) routine use of multiple IORT fields that necessitates field matching. The IORT applicator system and related devices and techniques are dosimetrically characterized in detail both for use in the IORT program and in order to illustrate many useful facets of electron dosimetry.

Energy Technology Data Exchange (ETDEWEB)

Time-resolved characterizations of electron beams using optical transition radiation (OTR) as a prompt conversion mechanism have recently been extended on the Los Alamos Free-electron Laser (FEL) facility 40-MeV linac. Two key timescales for rf-linac driven FELs are the micropulse (10 ps) and the macropulse (5 [mu]s to 1 ms). In the past we have used gated, intensified cameras to select a single or few micropulses (25 to 400 ns gate width) out of the pulse train to evaluate submacropulse effects. Recently, we have obtained some of the first measurements of micropulse bunch length (7 to 10 ps) and submacropulse spatialposition and profile using OTR and a Hamamatsu streak camera. Additionally, micropulse elongation effects and head-to-tail transverse kick effects are reported as a function of charge.

Energy Technology Data Exchange (ETDEWEB)

The multi-faceted research effort of the EBIT (Electron Beam Ion Trap) program in N-Division of the Physics and Space Technology Department at Lawrence Livermore National Laboratory (LLNL) continues to contribute significant results to the physical sciences from studies with low energy very highly charged heavy ions. The EBIT program attracts a number of collaborators from the US and abroad for the different projects. The collaborations are partly carried out through participating graduate students demonstrating the excellent educational capabilities at the LLNL EBIT facilities. Moreover, participants from Historically Black Colleges and Universities are engaged in the EBIT project. This report describes EBIT work for 1995 in atomic structure measurements and radiative transition probabilities, spectral diagnostics for laboratory and astrophysical plasmas, ion/surface interaction studies, electron-ion interactions studies, ...