Development of a Telescope for Medium-Energy Gamma-ray Astronomy

Science.gov (United States)

Sunter, Stan

2012-01-01

Since the launch of AGILE and FERMI, the scientific progress in high-energy (Eg greater than approximately 200 MeV) gamma-ray science has been, and will continue to be dramatic. Both of these telescopes cover a broad energy range from approximately 20 MeV to greater than 10 GeV. However, neither instrument is optimized for observations below approximately 200 MeV where many astrophysical objects exhibit unique, transitory behavior, such as spectral breaks, bursts, and flares. Hence, while significant progress from current observations is expected, there will nonetheless remain a significant sensitivity gap in the medium-energy (approximately 0.1-200 MeV) regime; the lower end of this range remains largely unexplored whereas the upper end will allow comparison with FERMI data. Tapping into this unexplored regime requires significant improvements in sensitivity. A major emphasis of modern detector development, with the goal of providing significant improvements in sensitivity in the medium-energy regime, focuses on high-resolution electron tracking. The Three-Dimensional Track Imager (3-DTI) technology being developed at GSFC provides high resolution tracking of the electron-positron pair from gamma-ray interactions from 5 to 200 MeV. The 3-DTI consists of a time projection chamber (TPC) and 2-D cross-strip microwell detector (MWD). The low-density and homogeneous design of the 3-DTI, offers unprecedented sensitivity by providing angular resolution near the kinematic limit. Electron tracking also enables measurement of gamma-ray polarization, a new tool to study astrophysical phenomenon. We describe the design, fabrication, and performance of a 30x30x30 cm3 3-DTI detector prototype of a medium-energy gamma-ray telescope.

Nuclear structure studies by the scattering of medium-energy electrons. Progress report, September 1, 1984-August 31, 1985

International Nuclear Information System (INIS)

Peterson, G.A.; Hicks, R.S.

1985-09-01

The University of Massachusetts Medium Energy Nuclear Physics Group reports the status of its experimental and theoretical programs. An overview of projects in elastic and quasi-elastic electron scattering which have been completed in the past year is given. Projects which have been designed and which will soon be started are described as well. Descriptions of the theoretical models for nucleon-nucleon interactions, nuclear structure, electromagnetic interactions, and weak interactions are given as well. Listings of the literature of the group are given

[Medium energy physics at Syracuse University: Technical progress report

International Nuclear Information System (INIS)

Souder, P.A.

1986-01-01

The primary focus of research has been an experiment at the MIT-Bates Linear Accelerator Center to measure the spin-dependence of elastic scattering of electrons from carbon. The Syracuse University Medium Energy Physics Group is also part of a collaboration which will measure the tensor polarization of deuterons scattered by electrons. Finally, analysis has been completed for an experiment at LAMPF in which the first observation of the exotic ion μ + e - e - was made. 17 refs., 18 figs., 2 tabs

Experimental medium energy physics: Annual progress report June 1987--May 1988

International Nuclear Information System (INIS)

1988-01-01

This report discusses progress in experimental medium energy physics at Carnegie Mellon University. Some of the topics covered are: search for the ξ(2230); hyperon-antihyperon production studies; relativistic proton-nucleus and heavy ion-nucleus collisions; H dibaryon physics; hypernuclear physics research; pion physics; H particle experiment design and development; and electron scattering

A real-time low energy electron calorimeter

International Nuclear Information System (INIS)

Mod Ali, N.; Smith, F.A.

1999-01-01

A real-time low energy electron calorimeter with a thin film window has been designed and fabricated to facilitate a reliable method of dose assessment for electron beam energies down to 200 keV. The work was initiated by the Radiation Physics Group of Queen Mary and Westfield College in collaboration with the National Physical Laboratory (NPL), Teddington. Irradiations were performed on the low and medium electron energy electron accelerators at the Malaysian Institute for Nuclear Technology Research (MINT). Calorimeter response was initially tested using the on-line temperature measurements for a 500-keV electron beam. The system was later redesigned by incorporating a data-logger to use on the self-shielded 200-keV beam. In use, the final version of the calorimeter could start logging temperature a short time before the calorimeter passed under the beam and continue measurements throughout the irradiation. Data could be easily retrieved at the end of the exposure. (author)

A Pair Production Telescope for Medium-Energy Gamma-Ray Polarimetry

Science.gov (United States)

Hunter, Stanley D.; Bloser, Peter F.; Depaola, Gerardo; Dion, Michael P.; DeNolfo, Georgia A.; Hanu, Andrei; Iparraguirre, Marcos; Legere, Jason; Longo, Francesco; McConnell, Mark L.;

Medium-Energy Nuclear Data Library (MENDLIB): Phase 1

International Nuclear Information System (INIS)

Siciliano, E.R.; Arthur, E.D.

1987-10-01

This document describes an initial step towards the formation of a computerized on-line data library, which would contain published medium-energy experimental data, and which would serve the basic and applied needs of the medium-energy nuclear physics community. The data emphasized in this project will be from measured charged-particle and meson induced nuclear scattering and reactions; an area for which no such data base presently exists. Access to the data will be through a menu-driven program in a user-friendly environment. The project is divided into three phases: Phase 1 involves compilation of Clinton P. Anderson Meson Physics Facility (LAMPF) data from nucleon and pion induced reactions, Phase 2 includes nucleon and pion data from other medium-energy facilities, and Phase 3 includes electron, light-ion, and possibly kaon and anti-nucleon data. The initial goals, the manner in which they would be pursued, and the resources needed to implement Phase 1 (the pilot phase) are discussed in detail. Possible expansion of Phase 1 to attain the envisioned goals of Phase 2 and 3 are briefly outlined. During all stages of the project, input from the community will be sought via the various facility user groups and the American Physical Society Division of Nuclear Physics. It is proposed that the Applied Nuclear Science Group (T-2) of the Los Alamos National Laboratory oversees the development and implementation of this project, and the LAMPF VAX computers be used as the host computers for on-line access

A Harmonic Kicker Scheme for the Circulator Cooler Ring in the Proposed Medium Energy Electron-Ion Collider

Energy Technology Data Exchange (ETDEWEB)

Nissen, Edward W.; Hutton, Andrew M.; Kimber, Andrew J.

2013-06-01

The current electron cooler design for the proposed Medium Energy Electron-Ion collider (MEIC) at Jefferson Lab utilizes a circulator ring for reuse of the cooling electron bunch up to 100 times to cool the ion beams. This cooler requires a fast kicker system for injecting and extracting individual bunches in the circulator ring. Such a kicker must work at a high repetition rate, up to 7.5 to 75 MHz depending on the number of turns in the recirculator ring. It also must have a very short rise and fall time (of order of 1 ns) such that it will kick an individual bunch without disturbing the others in the ring. Both requirements are orders of magnitude beyond the present state-of-the-art as well as the goals of other on-going kicker R&D programs such as that for the ILC damping rings. In this paper we report a scheme of creating this fast, high repetition rate kicker by combining RF waveforms at multiple frequencies to create a kicker waveform that will, for example, kick every eleventh bunch while leaving the other ten unperturbed. We also present a possible implementation of this scheme as well as discuss its limitations.

Medium-energy physics program. Progress report, February 1--April 1, 1976

Energy Technology Data Exchange (ETDEWEB)

Dunn, E. (comp.)

1976-09-01

A quarterly report on the medium-energy physics program at LAMPF is given. Topics covered include: (1) engineering support; (2) accelerator support; (3) accelerator systems development; (4) injector systems; (5) electronic instrumentation and computer systems; (6) accelerator operations; (7) experimental areas; (8) beam line development; (9) large-spectrometer systems; (10) research; (11) nuclear chemistry; (12) practical applications of LAMPF; and (13) management. (PMA)

Medium-energy physics program. Progress report, February 1--April 1, 1976

International Nuclear Information System (INIS)

Dunn, E.

1976-09-01

A quarterly report on the medium-energy physics program at LAMPF is given. Topics covered include: (1) engineering support; (2) accelerator support; (3) accelerator systems development; (4) injector systems; (5) electronic instrumentation and computer systems; (6) accelerator operations; (7) experimental areas; (8) beam line development; (9) large-spectrometer systems; (10) research; (11) nuclear chemistry; (12) practical applications of LAMPF; and (13) management

Medium properties and total energy coupling in underground explosions

International Nuclear Information System (INIS)

Kurtz, S.R.

1975-01-01

A phenomenological model is presented that allows the direct calculation of the effects of variations in medium properties on the total energy coupling between the medium and an underground explosion. The model presented is based upon the assumption that the shock wave generated in the medium can be described as a spherical blast wave at early times. The total energy coupled to the medium is then simply the sum of the kinetic and internal energies of this blast wave. Results obtained by use of this model indicate that the energy coupling is more strongly affected by the medium's porosity than by its water content. These results agree well with those obtained by summing the energy deposited by the blast wave as a function of range

On the fine structure of medium energy electron fluxes in the auroral zone and related effects in the ionospheric D-region

Directory of Open Access Journals (Sweden)

J. K. Hargreaves

2010-05-01

Full Text Available This study is based on measurements of trapped and precipitated electrons of energy >30 keV and >100 keV observed by polar orbiting environmental satellites during overpasses of the imaging riometer at Kilpisjärvi, Finland. The satellites are in sun-synchronous orbits of about 850 km altitude, recording the electron fluxes at 2-s time resolution. The riometer measures the radiowave absorption at 38.2 MHz, showing the spatial pattern within a 240 km field of view. The analysis has focussed on two areas. Having found a close correlation between the radiowave absorption and the medium-energy electron fluxes during satellite overpasses, empirical relationships are derived, enabling one quantity to be predicted from the other for three sectors of local time. It is shown that small-scale variations observed during a pass are essentially spatial rather than temporal. Other properties, such as the spectra and the relation between precipitated and trapped components, are also considered in the light of the theory of pitch angle scattering by VLF waves. It is found that the properties and behaviour depend strongly on the time of day. In the noon sector, the precipitated and trapped fluxes are highly correlated through a square law relationship.

Influence of bone and fat on dose distribution in electron beams in a semi-infinite medium

International Nuclear Information System (INIS)

Sordo, A.

1983-12-01

Hitherto, physical and theoretical aspects of the influence of heterogeneities in radiotherapy by electron beams had not been enough considered. We have developped an experimental method which permitted us to analyze the effect of the hard bone and the fat on the depth dose distributions when an infinite medium is irradiated by high energy electron beams. We have incorporated the KR. HOGSTROM's algorithm in a treatment planning system (TP11; AECL). This algorithm sums the dose distribution of individual pencil beams. A comparison between calculated and measured isodose lines obtained in a heterogeneous medium, shows us the performance and limits of this algorithm [fr

Heavy quark energy loss in nuclear medium

International Nuclear Information System (INIS)

Zhang, Benr-Wei; Wang, Enke; Wang, Xin-Nian

2003-01-01

Multiple scattering, modified fragmentation functions and radiative energy loss of a heavy quark propagating in a nuclear medium are investigated in perturbative QCD. Because of the quark mass dependence of the gluon formation time, the medium size dependence of heavy quark energy loss is found to change from a linear to a quadratic form when the initial energy and momentum scale are increased relative to the quark mass. The radiative energy loss is also significantly suppressed relative to a light quark due to the suppression of collinear gluon emission by a heavy quark

Development of the Advanced Energetic Pair Telescope (AdEPT) for Medium-Energy Gamma-Ray Astronomy

Science.gov (United States)

Hunter, Stanley D.; Bloser, Peter F.; Dion, Michael P.; McConnell, Mark L.; deNolfo, Georgia A.; Son, Seunghee; Ryan, James M.; Stecker, Floyd W.

2011-01-01

Progress in high-energy gamma-ray science has been dramatic since the launch of INTEGRAL, AGILE and FERMI. These instruments, however, are not optimized for observations in the medium-energy (approx.0.3< E(sub gamma)< approx.200 MeV) regime where many astrophysical objects exhibit unique, transitory behavior, such as spectral breaks, bursts, and flares. We outline some of the major science goals of a medium-energy mission. These science goals are best achieved with a combination of two telescopes, a Compton telescope and a pair telescope, optimized to provide significant improvements in angular resolution and sensitivity. In this paper we describe the design of the Advanced Energetic Pair Telescope (AdEPT) based on the Three-Dimensional Track Imager (3-DTI) detector. This technology achieves excellent, medium-energy sensitivity, angular resolution near the kinematic limit, and gamma-ray polarization sensitivity, by high resolution 3-D electron tracking. We describe the performance of a 30x30x30 cm3 prototype of the AdEPT instrument.

Secondary electron emission from Au by medium energy atomic and molecular ions

CERN Document Server

Itoh, A; Obata, F; Hamamoto, Y; Yogo, A

2002-01-01

Number distributions of secondary electrons emitted from a Au metal surface have been measured for atomic and molecular ions of H sup + , He sup + , C sup + , N sup + , O sup + , H sup + sub 2 , H sup + sub 3 , HeH sup + , CO sup + and O sup + sub 2 in the energy range 0.3-2.0 MeV. The emission statistics obtained are described fairly well by a Polya function. The Polya parameter b, determining the distribution shape, is found to decrease monotonously with increasing emission yield gamma, revealing a surprising relationship of b gamma approx 1 over the different projectile species and impact energies. This finding supports certainly the electron cascading model. Also we find a strong negative molecular effect for heavier molecular ions, showing a significant reduction of gamma compared to the estimated values using constituent atomic projectile data.

Medium energy electron cooling R and D at Fermilab -- Context and status

International Nuclear Information System (INIS)

MacLachlan, J.A.

1996-05-01

Electron cooling at the proposed Recycler 8 GeV storage ring has been identified as a key element in exploiting the capacity of the Fermilab Main Injector for an additional factor of ten in Tevatron luminosity above the goal for the next collider run, ultimately to > 10 33 cm -2 s -1 . The most basic requirement for increased luminosity is a large stack of antiprotons cooled to emittance comparable to that of the proton beam. Although electron cooling is inferior to the stochastic technique for cooling large emittance beams, its rate is practically independent of the antiproton intensity. For cooling intense beams of low or moderate emittance, electron cooling excels. The realization of electron cooling for 8 GeV antiprotons requires major extension of existing practice in electron energy and length of the cooling interaction region. It will require 4.3 MeV dc electron beam maintaining high quality and precise collinearity with the antiprotons over a 66 m straight section. The initial goal of the R and D project is 200 mA electron current in about three years; the plan is to reach 2 A over the following three years

Wakefields generated by electron beams passing through a waveguide loaded with a slightly dispersive active medium

Directory of Open Access Journals (Sweden)

Andrey V. Tyukhtin

2007-05-01

Full Text Available The wakefields of a relativistic electron beam passing through a waveguide loaded with an active medium with weak resonant dispersion are considered. For the calculations in this paper, the parameters of the medium are those of a solution of fullerene (C_{60} in a nematic liquid crystal that exhibits activity in the X-band. It is shown that several of the TM accelerating modes can be amplified for the geometries under consideration; structures in which higher order modes are amplified exhibit essential advantages as PASERs. In particular, the amplification of the highest mode occurs in a structure loaded with a rather thick active medium layer that maximizes the energy stored by the active medium.

Medium modifications of vector mesons

International Nuclear Information System (INIS)

Pant, L.M.

2004-01-01

The omega photoproduction in nuclear medium with the ELSA facility at Bonn and the present status of the HADES collaboration to investigate the in-medium hadron properties in proton, heavy ions and hadron induced reactions at GSI, Darmstadt are presented. Efforts are under way to utilise the electron beam at Indore for experimental hadron physics in order to step into the intermediate energy nuclear physics regime. The skeletal outline of the high energy electron beam now available at CAT, Indore is discussed

Interaction of low-energy electrons and positrons with condensed matter: Stopping powers and inelastic mean free paths from optical data

International Nuclear Information System (INIS)

Ashley, J.C.

1989-01-01

An ''optical-data model'' is described for evaluating energy loss per unit pathlength and inelastic mean free path for low-energy electrons and positrons (approx lt 10 keV) from optical data on the medium of interest. Exchange between the incident electron and electrons in the medium is included. Results from the optical-data model are compared with previous theoretical calculations. 15 refs., 6 figs., 2 tabs

Evaluating the Benefits of Electronic Commerce in Small and Medium Enterprises

Directory of Open Access Journals (Sweden)

Peter Marshall

2002-05-01

Full Text Available This paper outlines and analyses the behaviours of small and medium enterprises with respect to the evaluation of electronic commerce investments, and the subsequent realisation of the anticipated benefits from those investments. The responses of executives who participated in the study suggested that on-going involvement in electronic commerce did not come cheaply. Nonetheless, our study suggests that there were generally ad hoc approaches to evaluation of the proposed electronic commerce investments, almost non-existent post-implementation reviews, few measures of success, and generally speaking, there was little evidence of there being proactive management of the realisation of benefits of those investments. Perhaps not surprisingly, the group interviewed seemed somewhat disappointed with the outcomes of their electronic commerce initiatives. The implications of these findings are discussed, particularly for countries where small and medium enterprises contribute a large proportion of total economic activity, and where thus it is vital for small and medium enterprises to successfully engage in electronic commerce if the country is to derive the benefits of the new economy.

The DHG sum rule measured with medium energy photons

International Nuclear Information System (INIS)

Hicks, K.; Ardashev, K.; Babusci, D.

1997-01-01

The structure of the nucleon has many important features that are yet to be uncovered. Of current interest is the nucleon spin-structure which can be measured by doing double-polarization experiments with photon beams of medium energies (0.1 to 2 GeV). One such experiment uses dispersion relations, applied to the Compton scattering amplitude, to relate measurement of the total reaction cross section integrated over the incident photon energy to the nucleon anomalous magnetic moment. At present, no single facility spans the entire range of photon energies necessary to test this sum rule. The Laser-Electron Gamma Source (LEGS) facility will measure the double-polarization observables at photon energies between 0.15--0.47 MeV. Either the SPring8 facility, the GRAAL facility (France), or Jefferson Laboratory could make similar measurements at higher photon energies. A high-precision measurement of the spin-polarizability and the Drell-Hearn-Gerasimov sum rule is now possible with the advent of high-polarization solid HD targets at medium energy polarized photon facilities such as LEGS, GRAAL and SPring8. Other facilities with lower polarization in either the photon beam or target (or both) are also pursuing these measurements because of the high priority associated with this physics. The Spin-asymmetry (SASY) detector that will be used at LEGS has been briefly outlined in this paper. The detector efficiencies have been explored with simulations studies using the GEANT software, with the result that both charged and uncharged pions can be detected with a reasonable efficiency (> 30%) over a large solid angle. Tracking with a TPC, which will be built at LEGS over the next few years, will improve the capabilities of these measurements

Charge-equilibrium and radiation of low-energy cosmic rays passing through interstellar medium

Science.gov (United States)

Rule, D. W.; Omidvar, K.

1977-01-01

The charge equilibrium and radiation of an oxygen and an iron beam in the MeV per nucleon energy range, representing a typical beam of low-energy cosmic rays passing through the interstellar medium, is considered. Electron loss of the beam has been taken into account by means of the First Born approximation allowing for the target atom to remain unexcited, or to be excited to all possible states. Electron capture cross sections have been calculated by means of the scaled Oppenheimer-Brinkman-Kramers approximation, taking into account all atomic shells of the target atoms. Radiation of the beam due to electron capture into the excited states of the ion, collisional excitation and collisional inner-shell ionization of the ions has been considered. Effective X-ray production cross sections and multiplicities for the most energetic X-ray lines emitted by the Fe and O beams have been calculated.

Radiosensitivity of chlorella after medium energy accelerated electron irradiation; Radiosensibilite des chlorelles aux electrons acceleres de moyenne energie

Energy Technology Data Exchange (ETDEWEB)

Roux, J C [commissariat a L' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

1966-06-01

The survival curves (capability of multiplication) of chlorella pyrenoidosa after irradiations can be used for soft electrons (0.65 and 1 MeV), hence penetrating into only 2 to 4 millimeters of water: the algae are laying on porous membranes and the doses are calculated from the power of the electron beam measured by the electric current on a metallic target or by Fricke's dosimetry. With these techniques, it is showed and discussed the part of anoxia in the radioprotection (magnitude or reduction of the dose calculated from the slope of survival curves: 2.5 ) that is more important than the restoration studied by the fractionation of the dose. The 0.65 and 1 MeV electrons have a biologic effect lesser than 180 keV X-rays (RBE - relative biological efficiency - calculated on the slope of survival curves is 0.92 in aerated irradiation, 0.56 in the deoxygenated irradiation). (author) [French] Les courbes de survie clonale (capacite de multiplication) de chlorella pyrenoidosa apres irradiation sont realisables meme avec des electrons peu energetiques (0.65 et 1 MeV), donc peu penetrants, par l'irradiation d'algues deposees sur membrane filtrante et grace au calcul de la dose a partir de l'energie du faisceau mesure par le courant que celui-ci cree dans une cible metallique ou par dosimetrie de Fricke. Par ces techniques, on a montre et discute le role de l'anoxie dans la radioprotection des chlorelles (facteur de reduction de la dose calcule sur la pente des courbes de survie de 2.5) qui est plus important que le pouvoir de restauration etudie par le fractionnement de la dose. Les electrons utilises ont un effet biologique moins grand que les rayons X de 180 keV (l'efficacite biologique relative - EBR - calculee sur la pente des courbes de survie est de 0.9 en presence d'air, 0.6 en presence d'azote)

Medium-energy charged-particle data for evaluation

International Nuclear Information System (INIS)

Pearlstein, S.

1989-01-01

Medium-energy charged particles incident on targets can cause a variety of nuclear reactions. Charged-particle transport calculations require access to a large body of cross-section data, which results in interest in an evaluated charged-particle data library. Developing an evaluated data library can involve several steps. An index to the literature on measurements and theory is useful to locate information relevant to data evaluation. A computerized compilation of measurements facilitates the intercomparison of different experiments and the determination of how well data are known. Nuclear models, based on theory or phenomenological evidence, are compared with experiment and, where validated, are used to fill in regions where experimental data are not available. Finally, the selected data are placed into computer-readable formats for use in transport calculations. Specialized indexes to bibliography help the scientist to keep up with his field and catch up with new subjects of interest. Several indexes are relevant to medium-energy nuclear data. In addition, these data are covered in several reports not issued on a regular basis. The technical area of medium-energy charged-particle data is maturing. From isolated measurements and theories, a comprehensive approach toward establishing a validated data base extending from low to high energies is emerging

Precompound decay models for medium energy nuclear reactions

International Nuclear Information System (INIS)

Blann, M.

1989-11-01

The formulations used for precompound decay models are presented and explained in terms of the physics of the intranuclear cascade model. Several features of spectra of medium energy (10--1000 MeV) reactions are summarized. Results of precompound plus evaporation calculations from the code ALICE are compared with a wide body of proton, alpha, and heavy ion induced reaction data to illustrate both the power and deficiencies of predicting yield of these reactions in the medium energy regime. 23 refs., 13 figs

The Role of Low-Energy Electrons in Astrochemistry: A Tale of Two Molecules

Science.gov (United States)

Arumainayagam, Chris; Cambell, Jyoti; Leon Sanche, Michael Boyer, and Petra Swiderek.

2016-06-01

In the interstellar medium, UV photolysis of ice mantles encasing dust grains is thought to be the mechanism that drives the synthesis of “complex” molecules. The source of this reaction-initiating UV light is assumed to be local because externally-sourced UV radiation cannot pass through the ice-containing dark, dense molecular clouds. Externally sourced cosmic rays (Emax ~ 1020 eV), in addition to producing UV light within these clouds, also produce large numbers of low-energy (≤ 20 eV) secondary electrons. The goal of our studies is to understand the low-energy electron-induced processes that occur when high-energy cosmic rays interact with interstellar ices. Using electron stimulated desorption (ESD), post-irradiation temperature-programmed desorption (TPD), and infrared reflection absorption spectroscopy (IRAS), we have investigated the radiolysis initiated by electrons in condensed methanol and ammonia at ~ 90 K under ultrahigh vacuum (1×10-9 Torr) conditions. We have identified fifteen low-energy (≤ 20 eV) electron-induced methanol radiolysis products, many of which have been previously identified as being formed by methanol UV photolysis in the interstellar medium. We have also found evidence for the electron-induced formation from ammonia of hydrazine (N2H4), diazene (N2H2), cyclotriazane/triazene (N3H3) and triazane (N3H5). We have investigated the reaction yields’ dependence on film thickness, irradiation time, incident current, electron energy, and metal substrate. These results provide a basis from which we can begin to understand the mechanisms by which methanol and ammonia can form more complex species in cosmic ices. Studies such as ours may ultimately help us better understand the initial stages of the genesis of life.

Gamma-ray astronomy in the medium energy (10-50 MeV) range

International Nuclear Information System (INIS)

Kniffen, D.A.; Bertsch, D.L.; Palmeira, R.A.R.; Rao, K.R.

1977-01-01

Gamma-ray astronomy in the medium energy (10-50 MeV) range can provide unique information with which to study many astrophysical problems. Observations in the 10-50 MeV range provide the cleanest window with which to view the isotropic diffuse component of the radiation and to study the possible cosmological implications of the spectrum. For the study of compact sources, this is the important region between the X-ray sky and the vastly different γ-ray sky seen by SAS-2 and COS-B. To understand the implications of medium energy γ-ray astronomy to the study of the galactic diffuse γ-radiation, the model developed to explain the high energy γ-ray observations of SAS-2 is extended to the medium energy range. This work illustrates the importance of medium energy γ-ray astronomy for studying the electromagnetic component of the galactic cosmic rays. To observe the medium energy component of the intense galactic center γ-ray emission, two balloon flights of a medium energy γ-ray spark chamber telescope were flown in Brazil in 1975. These results indicate the emission is higher than previously thought and above the predictions of the theoretical model

BSRF-3B3 Medium Energy X-ray Beamline and Its Application for XAFS Research

International Nuclear Information System (INIS)

Ma Chenyan; Cui Mingqi; Zhou Kejin; Zhao Yidong; Tian Yulian; Wu Ziyu; Zheng Lei; Zhu Jie; Zhao Jia; Chen Kai; Sun Lijuan

2007-01-01

A new medium X-ray beamline 3B3 covering energy from 1.2 keV up to 6.0 keV was built at Beijing Synchrotron Radiation Facility (BSRF) in 2005. With perfect capability of high monochromaticity, good focus and low harmonics, it could be applied to study metrology, optic component characteristics and medium X-ray absorption spectroscopy (XAS). A simple XAFS apparatus has been set up and some measurements such as S, P, Cl, Ca, Al, Mg K-edge X-ray absorption fine structure (XAFS) in their compounds have also been carried out. The results show that it is feasible to do XAFS research at 3B3 beamline under present condition. The fabrication of a more delicate medium XAFS spectrometer is underway including transmission, fluorescence and electronic yield modes

Diagnosis and dynamics of low energy electron beams using DIADYN

International Nuclear Information System (INIS)

Marghitu, S.; Oproiu, C.; Toader, D.; Ruset, C.; Grigore, E.; Marghitu, O.; Vasiliu, M.

2008-01-01

The paper presents original results concerning electron beam diagnosis and dynamics using DIADYN, a low energy (10 - 50 kV), medium intensity (0.1 - 1 A) laboratory equipment. A key stage in the operation of DIADYN is the beam diagnosis, performed by the non-destructive, modified three-gradient method (MTGM). We concentrate on the better use of experimental and computational techniques, in order to improve the consistency of the results. At present, DIADYN is equipped with a hot filament vacuum electron source (VES), consisting of a convergent Pierce diode, working in a pulse mode. Since the plasma electron sources (PES) have a longer lifetime and produce higher beam currents, we discuss the possibility to replace the VES with a PES. Special attention is given to VES results in a functioning regime typical for a low energy glow discharge PES. (authors)

Diagnosis and dynamics of low energy electron beams using DIADYN

Energy Technology Data Exchange (ETDEWEB)

Marghitu, S [Electrostatica, ICPE-CA S.A., Spaiul Unirii 313, Sector 3, RO-74204 Bucharest (Romania); Oproiu, C; Toader, D; Ruset, C; Grigore, E [National Institute for Laser, Plasma and Radiation Physics, PO Box MG-36, 409 Atomistilor Street, RO-76900 Bucharest-Magurele (Romania); Marghitu, O [Institute for Space Sciences, INCDLPFR, PO Box MG-23, RO-76911 Bucharest-Magurele (Romania); Vasiliu, M [Politehnica University, 313 Splaiul Independentei, RO-060032, Bucharest (Romania)

2008-07-01

The paper presents original results concerning electron beam diagnosis and dynamics using DIADYN, a low energy (10 - 50 kV), medium intensity (0.1 - 1 A) laboratory equipment. A key stage in the operation of DIADYN is the beam diagnosis, performed by the non-destructive, modified three-gradient method (MTGM). We concentrate on the better use of experimental and computational techniques, in order to improve the consistency of the results. At present, DIADYN is equipped with a hot filament vacuum electron source (VES), consisting of a convergent Pierce diode, working in a pulse mode. Since the plasma electron sources (PES) have a longer lifetime and produce higher beam currents, we discuss the possibility to replace the VES with a PES. Special attention is given to VES results in a functioning regime typical for a low energy glow discharge PES. (authors)

Stopping power and energy loss cross section of a point charge penetrating through a dense medium of bound electrons

International Nuclear Information System (INIS)

Belkacem, A.; Sigmund, P.; Odense Univ.

1989-01-01

We have derived the dielectric function ε(k,ω) in the Lindhard approximation for a medium consisting of electrons individually bound by harmonic forces. The dielectric function is expressible in terms of a hypergeometric series and approaches well-known results in the limits of negligible binding, large momentum transfer, and long wavelength, respectively. The stopping power of a moving point charge scales very well with the shifted resonance frequency α 0 = (ω O 2 + ω P 2 ) 1/2 (ω O = oscillator frequency; ω P = plasma frequency) that follows from classical dispersion theory. The results differ noticeably from free-electron behavior even at rather high electron density. The discrete excitation levels of an isolated harmonic oscillator are increasingly shifted and broadened with increasing electron density. 15 refs., 2 figs

Ion-induced particle desorption in time-of-flight medium energy ion scattering

Science.gov (United States)

Lohmann, S.; Primetzhofer, D.

2018-05-01

Secondary ions emitted from solids upon ion impact are studied in a time-of-flight medium energy ion scattering (ToF-MEIS) set-up. In order to investigate characteristics of the emission processes and to evaluate the potential for surface and thin film analysis, experiments employing TiN and Al samples were conducted. The ejected ions exhibit a low initial kinetic energy of a few eV, thus, requiring a sufficiently high acceleration voltage for detection. Molecular and atomic ions of different charge states originating both from surface contaminations and the sample material are found, and relative yields of several species were determined. Experimental evidence that points towards a predominantly electronic sputtering process is presented. For emitted Ti target atoms an additional nuclear sputtering component is suggested.

In-medium effects around the Fermi energy

Directory of Open Access Journals (Sweden)

Lopez O.

2015-01-01

Full Text Available We study nuclear stopping in central collisions for heavy-ion induced reactions in the Fermi energy domain (15-100 AMeV. Using the large dataset provided by the 4π array INDRA, we determine that stopping can be directly related to the transport properties in the nuclear medium. By looking specifically at protons, we present a comprehensive body of experimental results concerning the mean free path, the nucleon-nucleon cross-section and in-medium effects in nuclear matter.

Auroral electron energies

International Nuclear Information System (INIS)

McEwan, D.J.; Duncan, C.N.; Montalbetti, R.

1981-01-01

Auroral electron characteristic energies determined from ground-based photometer measurements of the ratio of 5577 A OI and 4278 A N 2 + emissions are compared with electron energies measured during two rocket flights into pulsating aurora. Electron spectra with Maxwellian energy distributions were observed in both flights with an increase in characteristic energy during each pulsation. During the first flight on February 15, 1980 values of E 0 ranging from 1.4 keV at pulsation minima to 1.8 keV at pulsation maxima were inferred from the 5577/4278 ratios, in good agreement with rocket measurements. During the second flight on February 23, direct electron energy measurements yielded E 0 values of 1.8 keV rising to 2.1 keV at pulsation maxima. The photometric ratio measurements in this case gave inferred E 0 values about 0.5 keV lower. This apparent discrepancy is considered due to cloud cover which impaired the absolute emission intensity measurements. It is concluded that the 5577/4278 ratio does yield a meaningful measure of the characteristic energy of incoming electrons. This ratio technique, when added to the more sensitive 6300/4278 ratio technique usable in stable auroras can now provide more complete monitoring of electron influx characteristics. (auth)

Charge equilibrium and radiation of low-energy cosmic rays passing through interstellar medium

International Nuclear Information System (INIS)

Rule, D.W.; Omidvar, K.

1979-01-01

The charge equilibrium and radiation an oxygen and an iron beam in the MeV per nucleon energy range, representing a typical beam of low-energy cosmic rays passing through the interstellar medium, are considered. Electron loss of the beam has been taken into account by means of the first Born approximation allowing for the target atom to remain unexcited, or to be excited to all possible states. Electron-capture cross sections have been calculated by means of the scaled Oppenheimer-Brinkman-Kramers approximation, taking into account of atomic shells of the target atoms and capture into all excited states of the projectile. The capture and loss cross sections are found to be within 20%--30% of the existing experimental values for most of the cases considered. Radiation of the beam due to electron capture into the excited states of the ion, collisional excitation, and collisional inner-shell ionization, taking into account the fluorescence yield of the ions has been considered. Effective X-ray production cross sections and mutliplicities for the most energetic X-ray lines emitted by the Fe and O beams have been calculated, and error estimates made for the results

Charge equilibrium and radiation of low-energy cosmic rays passing through interstellar medium

Science.gov (United States)

Rule, D. W.; Omidvar, K.

1979-01-01

The charge equilibrium and radiation of an oxygen and an iron beam in the MeV per nucleon energy range, representing a typical beam of low-energy cosmic rays passing through the interstellar medium, are considered. Electron loss of the beam has been taken into account by means of the first Born approximation, allowing for the target atom to remain unexcited or to be excited to all possible states. Electron-capture cross sections have been calculated by means of the scaled Oppenheimer-Brinkman-Kramers approximation, taking into account all atomic shells of the target atoms and capture into all excited states of the projectile. The capture and loss cross sections are found to be within 20%-30% of the existing experimental values for most of the cases considered. Radiation of the beam due to electron capture into the excited states of the ion, collisional excitation, and collisional inner-shell ionization, taking into account the fluorescence yield of the ions, has been considered. Effective X-ray production cross sections and multiplicities for the most energetic X-ray lines emitted by the Fe and O beams have been calculated, and error estimates made for the results.

Time-domain electromagnetic energy in a frequency-dispersive left-handed medium

International Nuclear Information System (INIS)

Cui Tiejun; Kong Jinau

2004-01-01

From Maxwell's equations and the Poynting theorem, the time-domain electric and magnetic energy densities are generally defined in the frequency-dispersive media based on the conservation of energy. As a consequence, a general definition of electric and magnetic energy is proposed. Comparing with existing formulations of electric and magnetic energy in frequency-dispersive media, the new definition is more reasonable and is valid in any case. Using the new definition and staring from the equation of motion, we have shown rigorously that the total energy density and the individual electric and magnetic energy densities are always positive in a realistic artificial left-handed medium (LHM) [R. A. Shelby, D. R. Smith, and S. Schultz, Science 292, 77 (2001)], which obeys actually the Lorentz medium model, although such a LHM has negative permittivity and negative permeability simultaneously in a certain frequency range. We have also shown that the conservation of energy is not violated in LHM. The earlier conclusions can be easily extended to the Drude medium model and the cold plasma medium model. Through an exact analysis of a one-dimensional transient current source radiating in LHM, numerical results are given to demonstrate that the work done by source, the power flowing outwards a surface, and the electric and magnetic energy stored in a volume are all positive in the time domain

Spin effects in medium-energy electron-3He scattering

International Nuclear Information System (INIS)

van den Brand, J.F.J.; Alarcon, R.; Bauer, T.

1998-01-01

New physics can be accessed by scattering polarized electrons from a polarized 3 He internal gas target. It is discussed how the asymmetries for the reactions 3 vector He(vector e,e'), 3 vector He(vector e,e'p), 3 vector He(vector e,e'n), 3 vector He(vector e,e'd), and 3 vector He(vector e,e'pn) may provide precise information on the S' and the D-wave parts of the 3 He ground-state wave function, the neutron form factors, and the role of spin-dependent reaction mechanism effects. The experiment uses up to 900 MeV (polarized) electrons from the AmPS storage ring in Amsterdam, Netherlands, in combination with large acceptance electron and hadron detectors. (orig.)

Lowest-energy cage structures of medium-sized (ZnO){sub n} clusters with n = 15 − 24

Energy Technology Data Exchange (ETDEWEB)

Tang, Lingli; Sai, Linwei [School of Mathematical Sciences, Dalian University of Technology, Dalian 116024, China and College of Advanced Science and Technology, Dalian University of Technology, Dalian 116024 (China); Zhao, Jijun, E-mail: zhaojj@dlut.edu.cn [College of Advanced Science and Technology, Dalian University of Technology, Dalian 116024, China and Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Dalian University of Technology), Ministry of Education, Dalian 116024 (China); Qiu, Ruifeng [School of Mathematical Sciences, Dalian University of Technology, Dalian 116024 (China)

2015-01-22

Fullerene-like cage structures of medium-sized (ZnO){sub n} clusters with n = 15 − 24 were generated by spiral algorithm and optimized using density functional theory calculations. Most of these lowest-energy cage structures contain only four-membered and six-membered rings, whereas eight-membered rings were found in the lowest-energy cages of (ZnO){sub n} (n = 19, 20, 23, 24). Our best cage configurations either reproduce or prevail the previously reported ones. The size-dependent electronic properties were also discussed.

Radiosensitivity of chlorella after medium energy accelerated electron irradiation

International Nuclear Information System (INIS)

Roux, J.C.

1966-06-01

The survival curves (capability of multiplication) of chlorella pyrenoidosa after irradiations can be used for soft electrons (0.65 and 1 MeV), hence penetrating into only 2 to 4 millimeters of water: the algae are laying on porous membranes and the doses are calculated from the power of the electron beam measured by the electric current on a metallic target or by Fricke's dosimetry. With these techniques, it is showed and discussed the part of anoxia in the radioprotection (magnitude or reduction of the dose calculated from the slope of survival curves: 2.5 ) that is more important than the restoration studied by the fractionation of the dose. The 0.65 and 1 MeV electrons have a biologic effect lesser than 180 keV X-rays (RBE - relative biological efficiency - calculated on the slope of survival curves is 0.92 in aerated irradiation, 0.56 in the deoxygenated irradiation). (author) [fr

Medium Access Control in Energy Harvesting - Wireless Sensor Networks

DEFF Research Database (Denmark)

Fafoutis, Xenofon

Focusing on Wireless Sensor Networks (WSN) that are powered by energy harvesting, this dissertation focuses on energy-efficient communication links between senders and receivers that are alternating between active and sleeping states of operation. In particular, the focus lies on Medium Access...

Medium energy probes and nuclear structure

International Nuclear Information System (INIS)

Ginocchio, J.N.

1984-01-01

In this paper we explore two topics. The first topic is the marriage of medium energy reaction theory with the interacting boson model of nuclei in such a way that the multiple scattering is summed to all orders. The second topic is an exactly solvable potential model which gives realistic shell model eigenfunctions which can be used to calculate static and transition nuclear densities. (orig./HSI)

Trapped electron decay by the thermally-assisted tunnelling to electron acceptors in glassy matrices. A computer simulation study

International Nuclear Information System (INIS)

Feret, B.; Bartczak, W.M.; Kroh, J.

1991-01-01

The Redi-Hopefield quantum mechanical model of the thermally-assisted electron transfer has been applied to simulate the decay of trapped electrons by tunnelling to electron acceptor molecules added to the glassy matrix. It was assumed that the electron energy levels in donors and acceptors are statistically distributed and the electron excess energy after transfer is dissipated in the medium by the electron-phonon coupling. The electron decay curves were obtained by the method of computer simulation. It was found that for a given medium there exists a certain preferred value of the electronic excess energy which can be effectively converted into the matrix vibrations. If the mismatch of the electron states on the donor and acceptor coincides with the ''resonance'' energy the overall kinetics of electron transfer is accelerated. (author)

Medium Energy Industrial Electron Beam Accelerator (ILU-EBA) at Navi Mumbai for technology demonstration and commercial operations

International Nuclear Information System (INIS)

Benny, P.G.; Khader, S.A.; Sarma, K.S.S.

2017-01-01

BARC in early nineties installed a unique high pulse-powered electron beam accelerator of energy 2 MeV, (for the first time in India), in Trombay for developing industrial applications. The accelerator was capable of delivering powered electron beams up to 20kW average beam power (with 1200kW peak pulse power) with energy range from 1 to 2 MeV. Several applications have been developed and commercially exploited in the field of polymer cross linking, degradation, crystalline alterations etc. In addition, applications pertaining to the environmental remediation using electron beams were also worked out. The facility has been relocated at Navi Mumbai a decade ago operated under BARC safety regulatory body and was developed into a technology demonstration cum commercial plant with several product handling gadgets to evaluate the feasibility of different EB treatment processes for the industry viz. waste water treatment, polymer modifications, recycling to name a few

The use of low energy electron accelerator for processing of liquid matter in Indonesia

International Nuclear Information System (INIS)

Danu, Sugiarto

2003-01-01

Activities of radiation processing in Indonesia covering various fields are reviewed. The low and medium energy electron accelerator specially designed for radiation processing of liquid materials is introduced. P3TIR-BATAN is mostly engaged in radiation processing in general with Co-60 source and electron accelerators (300 keV, 50 mA and 2 MeV, 10 mA). A private company, Gajah Tunggal, has an accelerator of 500 keV, 20 mA. The use of low energy electron accelerator to irradiate liquid matter matter such as natural rubber latex, polysaccharides, starch, chitosan and other natural polymers in Indonesia are reported and future program of national research cooperation between government institutions and private companies are described. (S. Ohno)

Track structure analysis illustrating the prominent role of low-energy electrons in radiobiological effects of low-LET radiations

International Nuclear Information System (INIS)

Nikjoo, H.; Goodhead, D.T.

1991-01-01

Monte Carlo track structure methods have been used to illustrate the importance of low-energy electrons produced by low-LET radiations. It is shown that these low-energy secondary electrons contribute substantially to the dose in all low-LET irradiations and are particularly efficient at producing highly localized clusters of atomic damage which may be responsible for a major part of the biological effectiveness of low-LET radiations. The data generated by Monte Carlo track structure techniques and by earlier semi-analytical methods based on the LET concept have been compared in terms of cumulative and differential fractions of total dose absorbed as a function of electron energy. The data show that low-energy secondary electrons account for up to nearly 50% of the total dose imparted to a medium when irradiated with electrons or photons. (author)

High-Energy Electron Beam Application to Air Pollutants Removal

International Nuclear Information System (INIS)

Ighigeanu, D.; Martin, D.; Manaila, E.; Craciun, G.; Calinescu, I.

2009-01-01

The advantage of electron beam (EB) process in pollutants removal is connected to its high efficiency to transfer high amount of energy directly into the matter under treatment. Disadvantage which is mostly related to high investment cost of accelerator may be effectively overcome in future as the result of use accelerator new developments. The potential use of medium to high-energy high power EB accelerators for air pollutants removal is demonstrated in [1]. The lower electrical efficiencies of accelerators with higher energies are partially compensated by the lower electron energy losses in the beam windows. In addition, accelerators with higher electron energies can provide higher beam powers with lower beam currents [1]. The total EB energy losses (backscattering, windows and in the intervening air space) are substantially lower with higher EB incident energy. The useful EB energy is under 50% for 0.5 MeV and about 95% above 3 MeV. In view of these arguments we decided to study the application of high energy EB for air pollutants removal. Two electron beam accelerators are available for our studies: electron linear accelerators ALIN-10 and ALID-7, built in the Electron Accelerator Laboratory, INFLPR, Bucharest, Romania. Both accelerators are of traveling-wave type, operating at a wavelength of 10 cm. They utilize tunable S-band magnetrons, EEV M 5125 type, delivering 2 MW of power in 4 μ pulses. The accelerating structure is a disk-loaded tube operating in the 2 mode. The optimum values of the EB peak current IEB and EB energy EEB to produce maximum output power PEB for a fixed pulse duration EB and repetition frequency fEB are as follows: for ALIN-10: EEB = 6.23 MeV; IEB =75 mA; PEB 164 W (fEB = 100 Hz, EB = 3.5 s) and for ALID-7: EEB 5.5 MeV; IEB = 130 mA; PEB = 670 W (fEB = 250 Hz, EB = 3.75 s). This paper presents a special designed installation, named SDI-1, and several representative results obtained by high energy EB application to SO 2 , NOx and VOCs

Medium-energy ion reflection from solids

CERN Document Server

Mashkova, ES

1985-01-01

``Medium-Energy Ion Reflection from Solids'' analyses the results of experimental, theoretical and computer investigations on the process of scattering of ions by solid surfaces. Surface scattering is a relatively young and rapidly developing branch of the physics of atomic collisions and the literature on this subject has rapidly grown.As the first monograph devoted specifically to surface scattering of ions, this book is directed at scientists involved in ion-solid interaction studies.

Energy dissipation during an explosion in a porous elasto-plastic medium

Energy Technology Data Exchange (ETDEWEB)

Lovetskii, E.E.; Maslennikov, A.M.; Fetisov, V.S.

1979-01-01

A study is made of the redistribution of energy from camouflage blasting in a saturated porous medium. The study is undertaken with the aid of a numerical solution to a system of hydrodynamic equations, that account for shear strength of the substance under investigation. A study is made of the energy characteristics of explosion, their dynamic development, the influence of strength parameters of the medium, and porosity on these characteristics. A mechanism that is associated with the impact compression of matter is identified as the basic mechanism of energy dissipation for dry porous media. Water saturation of pores brings the energy characteristics of the explosion close to the explosion in a monolith. 12 references, 5 figures, 1 table.

Medium and high energy electron beam processing system

Energy Technology Data Exchange (ETDEWEB)

Kashiwagi, Masayuki [Nissin-High Voltage Co., Ltd., Kyoto (Japan)

2003-02-01

Electron Beam Processing System (EPS) is a useful and powerful tool for industrial irradiation process. The specification of EPS is decided by consideration to irradiate what material with how thick and wide, how much dose, how to handle, in what atmosphere. In designing an EPS, it is necessary to consider safety measure such as x-ray shielding, ozone control and interlock system. The initial costs to install typical EPS are estimated for acceleration voltages from 500 kV to 5 MV, including following items; those are electron beam machine, x-ray shielding, auxiliary equipment, material handling, survey for installation, ozone exhaust duct, cooling water system, wiring and piping. These prices are reference only because the price should be changed for each case. The price of x-ray shielding should be changed by construction cost. Auxiliary equipment includes window, cooling blower, ozone exhaust blower and SF6 gas handling equipment. In installation work at site, actual workers of 3 - 4 persons for 2 months are necessary. Material handling system is considered only rolls provided in the shielding room as reference. In addition to the initial installation, operators and workers may be required to wear a personal radiation monitor. An x-ray monitor of suitable design should be installed outside the shield room to monitor x-ray level in the working area. (Y. Tanaka)

EELOSS: the program for calculation of electron energy loss data

International Nuclear Information System (INIS)

Tanaka, Shun-ichi

1980-10-01

A computer code EELOSS has been developed to obtain the electron energy loss data required for shielding and dosimetry of beta- and gamma-rays in nuclear plants. With this code, the following data are obtainable for any energy from 0.01 to 15 MeV in any medium (metal, insulator, gas, compound, or mixture) composed of any choice of 69 elements with atomic number 1 -- 94: a) Collision stopping power, b) Restricted collision stopping power, c) Radiative stopping power, and d) Bremsstrahlung production cross section. The availability of bremsstrahlung production cross section data obtained by the EELOSS code is demonstrated by the comparison of calculated gamma-ray spectrum with measured one in Pb layer, where electron-photon cascade is included implicitly. As a result, it is concluded that the uncertainty in the bremsstrahlung production cross sections is negligible in the practical shielding calculations of gamma rays of energy less than 15 MeV, since the bremsstrahlung production cross sections increase with the gamma-ray energy and the uncertainty for them decreases with increasing the gamma-ray energy. Furthermore, the accuracy of output data of the EELOSS code is evaluated in comparison with experimental data, and satisfactory agreements are observed concerning the stopping power. (J.P.N.)

Scattering amplitude and shift in self-energy in medium

International Nuclear Information System (INIS)

Mallik, S.

2002-01-01

Two simple proofs are presented for the first order virial expansion of the self-energy of a particle moving through a medium, characterised by temperature and/or chemical potential(s). One is based on the virial expansion of the self-energy operator itself, while the other is based on the analysis of its Feynman diagrams in configuration space. (orig.)

Technical Support Document: 50% Energy Savings Design Technology Packages for Medium Office Buildings

Energy Technology Data Exchange (ETDEWEB)

Thornton, Brian A.; Wang, Weimin; Lane, Michael D.; Rosenberg, Michael I.; Liu, Bing

2009-09-01

This Technical Support Document (TSD) describes the process and methodology for development of the Advanced Energy Design Guide for Medium Offices (AEDG-MO or the Guide), a design guidance document which intends to provide recommendations for achieving 50% energy savings in medium office buildings that just meet the requirements of ANSI/ASHRAE/IESNA Standard 90.1-2004, Energy Standard for Buildings Except Low-Rise Residential Buildings.

General theory for environmental effects on (vertical) electronic excitation energies.

Science.gov (United States)

Schwabe, Tobias

2016-10-21

Almost 70 years ago, the first theoretical model for environmental effects on electronic excitation energies has been derived. Since then, several different interpretations and refined models have been proposed for the perichromic shift of a chromophore due to its surrounding medium. Some of these models are contradictory. Here, the contributing terms are derived within the framework of long-range perturbation theory with the least approximations so far. The derivation is based on a state-specific interpretation of the interaction energies and all terms can be identified with individual properties of either the chromophore or the surroundings, respectively. Further, the much debated contribution due to transition moments coupled to the environment can be verified in the form of a non-resonant excitonic coupling to the dynamic polarizabilities in the environment. These general insights should clarify discussions and interpretations of environmental effects on electronic excitations and should foster the development of new models for the computation of these effects.

Electron energy-loss spectroscopy

International Nuclear Information System (INIS)

Egerton, R.

1997-01-01

As part of the commemorative series of articles to mark the hundredth anniversary of the discovery of the electron, this article discusses electron energy-loss spectroscopy. The physical and chemical properties of materials can be studied by considering the energy that electrons use as they travel through a solid, often in conjunction with other analytical techniques. The technique is often combined with electron diffraction and high-resolution imaging and can be used to provide elemental identification down to the atomic scale. (UK)

Magnetic energy analyser for slow electrons

International Nuclear Information System (INIS)

Limberg, W.

1974-08-01

A differential spectrometer with high time and energy resolution has been developed using the principle of energy analysis with a longitudinal homogeneous magnetic field. This way it is possible to measure the energy distribution of low energy electrons (eV-range) in the presence of high energy electrons without distortions by secondary electrons. The functioning and application of the analyzer is demonstrated by measuring the energy distributions of slow electrons emitted by a filament. (orig.) [de

The Role of Low-Energy (less than 20 eV) Electrons in Astrochemistry: A Tale of Two Molecules

Science.gov (United States)

Arumainayagam, Chris

2016-07-01

In the interstellar medium, UV photolysis of ice mantles encasing dust grains is thought to be the mechanism that drives the synthesis of "complex" molecules. The source of this reaction-initiating UV light is assumed to be local because externally-sourced UV radiation cannot pass through the ice-containing dark, dense molecular clouds. Externally sourced cosmic rays (E_{max} ˜10^{20} eV), in addition to producing UV light within these clouds, also produce large numbers of low-energy (≤ 20 eV) secondary electrons. The goal of our studies is to understand the low-energy electron-induced processes that occur when high-energy cosmic rays interact with interstellar ices. Using electron stimulated desorption (ESD), post-irradiation temperature-programmed desorption (TPD), and infrared reflection absorption spectroscopy (IRAS), we have investigated the radiolysis initiated by electrons in condensed methanol and ammonia at ˜90K under ultrahigh vacuum (1 × 10^{-9} Torr) conditions. We have identified fifteen low-energy electron-induced methanol radiolysis products, many of which have been previously identified as being formed by methanol UV photolysis in the interstellar medium. We have also found evidence for the electron-induced formation from ammonia of hydrazine (N_2 H_4), diazene (N_2 H_2), cyclotriazane/triazene (N_3 H_3) and triazane (N_3 H_5). We have investigated the reaction yields' dependence on film thickness, irradiation time, incident current, electron energy, and metal substrate. These results provide a basis from which we can begin to understand the mechanisms by which methanol and ammonia can form more complex species in cosmic ices. Studies such as ours may ultimately help us better understand the initial stages of the genesis of life.

Studies in medium energy physics

International Nuclear Information System (INIS)

Green, A.; Hoffmann, G.W.; McDonough, J.; Purcell, M.J.; Ray, R.L.; Read, D.E.; Worn, S.D.

1991-12-01

This document constitutes the (1991--1992) technical progress report and continuation proposal for the ongoing medium energy nuclear physics research program supported by the US Department of Energy through special Research Grant DE-FG05-88ER40444. The experiments discussed are conducted at the Los Alamos National Laboratory's (LANL) Clinton P. Anderson Meson Physics Facility (LAMPF) and the Alternating Gradient Synchrotron (AGS) facility of the Brookhaven National Laboratory (BNL). The overall motivation for the work discussed in this document is driven by three main objectives: (1) provide hadron-nucleon and hadron-nucleus scattering data which serve to facilitate the study of effective two-body interactions, test (and possibly determine) nuclear structure, and help study reaction mechanisms and dynamics; (2) provide unique, first-of-a-kind ''exploratory'' hadron-nucleus scattering data in the hope that such data will lead to discovery of new phenomena and new physics; and (3) perform precision tests of fundamental interactions, such as rare decay searches, whose observation would imply fundamental new physics

Observations of the scatter-free solar-flare electrons in the energy range 20-1000 keV

Science.gov (United States)

Wang, J. R.; Fisk, L. A.; Lin, R. P.

1971-01-01

Observations of the scatter-free electron events from solar active region McMath No. 8905 are presented. The measurements were made on Explorer 33 satellite. The data show that more than 80% of the electrons from these events undergo no or little scattering and that these electrons travel only approximately 1.5 a.u. between the sun and the earth. The duration of these events cannot be accounted fully by velocity dispersion alone. It is suggested that these electrons could be continuously injected into interplanetary medium for a time interval of approximately 2 to 3 minutes. Energy spectra of these electrons are discussed.

The inelastic scattering of medium energy α particles

International Nuclear Information System (INIS)

Crut, M.

1960-01-01

The aim of this work is to find out what are the properties of the so-called 'anomalous states' in medium weight nuclei. These states preferentially excited in the inelastic scattering of medium energy charged particles have an excitation energy at about 4 MeV for nuclei with Z ≤ 29 and in the range 2-3 MeV for high Z nuclei. From a combination of angular distribution data in the elastic and inelastic scattering of 30 MeV α particles, and correlation data between inelastic α particles and deexcitation γ rays, we show that for even-even nuclei, we can attribute spin 3 and parity minus to these 'anomalous states'. This is quite in agreement with the interpretation of these levels suggested by Lane as due to collective octupole oscillations. We give a resume of the theories used in the analysis of the data and a description of the experimental set-up. (author) [fr

electron energy-loss spectroscopy

International Nuclear Information System (INIS)

Egerton, R.

1997-01-01

As part of a commemorative series of articles to mark the hundredth anniversary of the discovery of the electron, this article describes the use of electron energy-loss spectroscopy. The physical and chemical properties of materials can be studied by considering the energy that electrons use as they travel through a solid, often in conjunction with other analytical techniques. The technique is often combined with electron diffraction and high-resolution imaging and can be used to provide elemental identification down to the atomic scale. 6 figs

Evaluation at the medium energy region for Pb-208 and Bi-209

International Nuclear Information System (INIS)

Fukahori, Tokio; Pearlstein, S.

1991-01-01

Medium energy nuclear data in the 1--1000 MeV range is necessary to accelerator applications which include spallation neutron sources for radioactive waste treatment and accelerator shielding design, medical applications which include isotopes production and radiation therapy, and space applications. For the design of fission and fusion reactors, the nuclear data file for neutrons below 20 MeV is available and well evaluated. Evaluated nuclear data for protons and data in the medium energy region, however, have not been prepared completely. Evaluation in the medium energy region was performed using the theoretical calculation code ALICE-P or experimental data. In this paper, the evaluation of neutron and proton induced nuclear data for Pb-208 and Bi-209 has been performed using ALICE-P, empirical calculations and new systematics for the fission cross section. The evaluated data are compiled for possible inclusion in the ENDF/B-VI High Energy File. 204 refs., 51 figs., 9 tabs

Distribution of separated energy and injected charge at normal falling of fast electron beam on target

CERN Document Server

Smolyar, V A; Eremin, V V

2002-01-01

In terms of a kinetic equation diffusion model for a beam of electrons falling on a target along the normal one derived analytical formulae for distributions of separated energy and injected charge. In this case, no empirical adjustable parameters are introduced to the theory. The calculated distributions of separated energy for an electron plate directed source within infinite medium for C, Al, Sn and Pb are in good consistency with the Spencer data derived on the basis of the accurate solution of the Bethe equation being the source one in assumption of a diffusion model, as well

Distribution of separated energy and injected charge at normal falling of fast electron beam on target

International Nuclear Information System (INIS)

Smolyar, V.A.; Eremin, A.V.; Eremin, V.V.

2002-01-01

In terms of a kinetic equation diffusion model for a beam of electrons falling on a target along the normal one derived analytical formulae for distributions of separated energy and injected charge. In this case, no empirical adjustable parameters are introduced to the theory. The calculated distributions of separated energy for an electron plate directed source within infinite medium for C, Al, Sn and Pb are in good consistency with the Spencer data derived on the basis of the accurate solution of the Bethe equation being the source one in assumption of a diffusion model, as well [ru

NaI(Tl) electron energy resolution

CERN Document Server

Mengesha, W

2002-01-01

NaI(Tl) electron energy resolution eta sub e was measured using the Modified Compton Coincidence Technique (MCCT). The MCCT allowed detection of nearly monoenergetic internal electrons resulting from the scattering of incident 662 keV gamma rays within a primary NaI(Tl) detector. Scattered gamma rays were detected using a secondary HPGe detector in a coincidence mode. Measurements were carried out for electron energies ranging from 16 to 438 keV, by varying the scattering angle. Measured HPGe coincidence spectra were deconvolved to determine the scattered energy spectra from the NaI(Tl) detector. Subsequently, the NaI(Tl) electron energy spectra were determined by subtracting the energy of scattered spectra from the incident source energy (662 keV). Using chi-squared minimization, iterative deconvolution of the internal electron energy spectra from the measured NaI(Tl) spectra was then used to determine eta sub e at the electron energy of interest. eta sub e values determined using this technique represent va...

Medium-term energy hub management subject to electricity price and wind uncertainty

International Nuclear Information System (INIS)

Najafi, Arsalan; Falaghi, Hamid; Contreras, Javier; Ramezani, Maryam

2016-01-01

Highlights: • A new model for medium-term energy hub management is proposed. • Risk aversion is considered in medium-term energy hub management. • Stochastic programing is used to solve the medium-term energy hub management problem. • Electricity price and wind uncertainty are considered. - Abstract: Energy hubs play an important role in implementing multi-carrier energy systems. More studies are required in both their modeling and operating aspects. In this regard, this paper attempts to develop medium-term management of an energy hub in restructured power systems. A model is presented to manage an energy hub which has electrical energy and natural gas as inputs and electrical and heat energy as outputs. Electricity is procured in various ways, either purchasing it from a pool-based market and bilateral contracts, or producing it from a Combined Heat and Power (CHP) unit, a diesel generator unit and Wind Turbine Generators (WTGs). Pool prices and wind turbine production are subject to uncertainty, which makes energy management a complex puzzle. Heat demand is also procured by a furnace and a CHP unit. Energy hub managers should make decisions whether to purchase electricity from the electricity market and gas from the gas network or to produce electricity using a set of generators to meet the electrical and heat demands in the presence of uncertainties. The energy management objective is to minimize the total cost subject to several technical constraints using stochastic programming. Conditional Value at Risk (CVaR), a well-known risk measure, is used to reduce the unfavorable risk of costs. In doing so, the proposed model is illustrated using a sample test case with actual prices, load and wind speed data. The results show that the minimum cost is obtained by the best decisions involving the electricity market and purchasing natural gas for gas facilities. Considering risk also increases the total expected cost and decreases the CVaR.

Can Low Energy Electrons Affect High Energy Physics Accelerators?

International Nuclear Information System (INIS)

Cimino, Roberto

2004-01-01

The properties of the electrons participating in the build up of an electron cloud (EC) inside the beam-pipe have become an increasingly important issue for present and future accelerators whose performance may be limited by this effect. The EC formation and evolution are determined by the wall-surface properties of the accelerator vacuum chamber. Thus, the accurate modeling of these surface properties is an indispensible input to simulation codes aimed at the correct prediction of build-up thresholds, electron-induced instability or EC heat load. In this letter, we present the results of surface measurements performed on a prototype of the beam screen adopted for the Large Hadron Collider (LHC), which presently is under construction at CERN. We have measured the total secondary electron yield (SEY) as well as the related energy distribution curves (EDC) of the secondary electrons as a function of incident electron energy. Attention has been paid, for the first time in this context, to the probability at which low-energy electrons (<∼ 20 eV) impacting on the wall create secondaries or are elastically reflected. It is shown that the ratio of reflected to true-secondary electrons increases for decreasing energy and that the SEY approaches unity in the limit of zero primary electron energy

High efficiency charge recuperation for electron beams of MeV energies

International Nuclear Information System (INIS)

MacLachlan, J.A.

1996-05-01

Electron cooling of ion beams with energies of some GeV per nucleon requires high-quality electron beams of MeV energies and currents as high as several amperes. The enormous beam power dictates that the beam current be returned to the high voltage terminal which provides the accelerating potential. The beam is returned to a carefully designed collector within the terminal and biased a few kV positive with respect to it. Thus the load on the HV supply is only the accelerating potential times the sum of the beam current loss and the current used to maintain a graded potential on the accelerating structure. If one employs an electrostatic HV supply like a Van de Graaff with maximum charging current of a few hundred microA, the permissible fractional loss is ∼ 10 -4 . During the 15 years or so the concept of medium energy electron cooling has been evolving, the need to demonstrate the practicability of such high efficiency beam recovery has been recognized. This paper will review some experimental tests and further experiments which have been proposed. The design and status are presented for a new re-circulation experiment at 2 MV being carried out by Fermilab at National Electrostatics Corp

Inelastic proton scattering at medium energy

International Nuclear Information System (INIS)

Love, W.G.

1980-01-01

Some of the most essential characteristics of the nucleon-nucleon interaction for probing nuclear structure at bombarding energies between 100 and 800 MeV are considered. With a local representation of the on-shell N-N t-matrix, data for a variety of specific transitions at IUCF and LAMPF energies are discussed with an emphasis on the nuclear structure information sampled by proton scattering. The importance of incorporating constraints on nuclear structure imposed by electron scattering is stressed. Some rather unique aspects of the (p,n) reaction at intermediate energies are discussed in terms of its energy dependence and nuclear structure sum rules. 11 figures

ρ-meson self-energy and dielectron emissivity in an isospin-asymmetric pion medium

International Nuclear Information System (INIS)

Titov, A.I.; Gulamov, T.I.; Kaempfer, B.

1996-01-01

The ρ-meson self-energy in an isospin-asymmetric pion gas at finite temperature and charged-pion chemical potential is evaluated. We utilize a conventional effective π-ρ Lagrangian and the functional integral representation of the partition function in the second order in the ρππ coupling constant. We analyze the ρ-meson polarization operator and its dependence on the invariant mass M and spatial momentum parallel p parallel of the ρ meson. The pole positions and the values of the imaginary parts of the self-energy for different polarization states have different functional dependences on M and parallel p parallel. The corresponding dielectron rate (calculated from the imaginary part of the in-medium ρ-meson propagator) shows a distinctive asymmetry when the momentum t=p + -p - is perpendicular or parallel to p, where p ± are the e ± momenta of the electron pair. copyright 1996 The American Physical Society

Medium energy measurements of n-n parameters. Progress report, January 1-December 31, 1985

International Nuclear Information System (INIS)

1986-01-01

This document constitutes a progress report (1985-86) for the ongoing medium energy nuclear physics research program. A major part of the work has been and will continue to be associated with research done at the Nucleon Physics Laboratory (NPL) at the Los Alamos Meson Physics Facility (LAMPF). The aim of the experimental program is the determination of the nucleon-nucleon amplitudes at medium energy. The required data include both elastic and inelastic experiments, and in addition the measurement of polarization and polarization transfer parameters. We have been emphasizing single pion production measurements using polarized proton beams, and expect that our present data base will provide stringent tests of theoretical models. With the development of the LAMPF high intensity polarized proton source, we expect that a reasonably intense beam of medium energy polarized neutrons will become available, and are planning a series of experiments utilizing polarized neutrons to determine the importance of the I = 0 reaction amplitudes at medium energies

Electron Linacs for High Energy Physics

International Nuclear Information System (INIS)

Wilson, Perry B.

2011-01-01

The purpose of this article is to introduce some of the basic physical principles underlying the operation of electron linear accelerators (electron linacs). Electron linacs have applications ranging from linacs with an energy of a few MeV, such that the electrons are approximately relativistic, to future electron-positron linear colliders having a collision energy in the several-TeV energy range. For the most part, only the main accelerating linac is treated in this article.

Introduction to electron beam processing

Energy Technology Data Exchange (ETDEWEB)

Kawakami, Waichiro [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

1994-12-31

The contents are general features in the irradiation of polymers, electron beam machines - low energy, medium energy, high energy; application of EB machine in industries, engineering of EB processing, dosimetry of EB (electron beam) safe operation of EB machine, recent topics on EB processing under development. 3 tabs., 4 figs., 17 refs.

Introduction to electron beam processing

International Nuclear Information System (INIS)

Waichiro Kawakami

1994-01-01

The contents are general features in the irradiation of polymers, electron beam machines - low energy, medium energy, high energy; application of EB machine in industries, engineering of EB processing, dosimetry of EB (electron beam) safe operation of EB machine, recent topics on EB processing under development. 3 tabs., 4 figs., 17 refs

Calculated sputtering and atomic displacement cross-sections for applications to medium voltage analytical electron microscopy

International Nuclear Information System (INIS)

Bradley, C.R.; Zaluzec, N.J.

1987-08-01

The development of medium voltage electron microscopes having high brightness electron sources and ultra-high vacuum environments has been anticipated by the microscopy community now for several years. The advantages of such a configuration have been discussed to great lengths, while the potential disadvantages have for the most part been neglected. The most detrimental of these relative to microcharacterization are the effects of electron sputtering and atomic displacement to the local specimen composition. These effects have in the past been considered mainly in the high voltage electron microscope regime and generally were ignored in lower voltage instruments. Recent experimental measurements have shown that the effects of electron sputtering as well as radiation induced segregation can be observed in conventional transmission electron microscopes. It is, therefore, important to determine at what point the effects will begin to manifest themselves in the new generation of medium voltage analytical electron microscopes. In this manuscript we present new calculations which allow the individual experimentalist to determine the potential threshold levels for a particular elemental system and thus avoid the dangers of introducing artifacts during microanalysis. 12 refs., 3 figs

Refinement of the AdEPT Medium-Energy Gamma-Ray Science

Data.gov (United States)

National Aeronautics and Space Administration — We propose to explore the theoretical framework for the relatively unexplored field of medium energy (5--200 MeV) gamma-ray astronomy for a mission concept...

Medium energy charged particle spectrometer

International Nuclear Information System (INIS)

Keppler, E.; Wilken, B.; Richer, K.; Umlauft, G.; Fischer, K.; Winterhoff, H.P.

1976-10-01

The charged particle spectrometer E8 on HELIOS A and B will be described in some detail. It covers proton energies from 80 keV to 6 MeV, electrons from 20 keV to 2 MeV, and positrons from 150 to 550 keV. Its flight performance will be discussed. From examples of measurements the capability of the instrument will be demonstrated. (orig.) [de

Void formation in NiTi shape memory alloys by medium-voltage electron irradiation

International Nuclear Information System (INIS)

Schlossmacher, P.; Stober, T.

1995-01-01

In-situ electron irradiation experiments of NiTi shape memory alloys, using high-voltage transmission electron microscopes, result in amorphization of the intermetallic compound. In all of these experiments high-voltages more than 1.0 MeV had to be applied in order to induce the crystalline-to-amorphous transformation. To their knowledge no irradiation effects of medium-voltage electrons of e.g. 0.5 MeV have been reported in the literature. In this contribution, the authors describe void formation in two different NiTi shape memory alloys, resulting from in-situ electron irradiation, using a 300 kV electron beam in a transmission electron microscope. First evidence is presented that void formation is correlated with the total oxygen content of the alloys

Transport calculation of medium-energy protons and neutrons by Monte Carlo method

International Nuclear Information System (INIS)

Ban, Syuuichi; Hirayama, Hideo; Katoh, Kazuaki.

1978-09-01

A Monte Carlo transport code, ARIES, has been developed for protons and neutrons at medium energy (25 -- 500 MeV). Nuclear data provided by R.G. Alsmiller, Jr. were used for the calculation. To simulate the cascade development in the medium, each generation was represented by a single weighted particle and an average number of emitted particles was used as the weight. Neutron fluxes were stored by the collisions density method. The cutoff energy was set to 25 MeV. Neutrons below the cutoff were stored to be used as the source for the low energy neutron transport calculation upon the discrete ordinates method. Then transport calculations were performed for both low energy neutrons (thermal -- 25 MeV) and secondary gamma-rays. Energy spectra of emitted neutrons were calculated and compared with those of published experimental and calculated results. The agreement was good for the incident particles of energy between 100 and 500 MeV. (author)

MEGA - A next generation mission in Medium Energy Gamma-Ray Astronomy

International Nuclear Information System (INIS)

Kanbach, Gottfried

2001-01-01

A Medium Energy Gamma-Ray Astronomy (MEGA) detector is being developed and proposed for a small satellite mission. MEGA intends to improve the sensitivity at medium γ-ray energies (0.4-50 MeV) by at least an order of magnitude with respect to past instruments. Its large field of view will be especially important for the discovery of transient sources and for conducting all-sky surveys. Key science objectives for MEGA are the investigation of cosmic high-energy accelerators and of nucleosynthesis sites with γ-ray lines. The large-scale structure of the galactic and cosmic diffuse background is another important goal for this mission. MEGA records and images γ-ray events by completely tracking Compton and pair creation interactions in a stack of double sided Si-strip track detectors and 3-D resolving CsI calorimeters

High-energy electron diffraction and microscopy

CERN Document Server

Peng, L M; Whelan, M J

2011-01-01

This book provides a comprehensive introduction to high energy electron diffraction and elastic and inelastic scattering of high energy electrons, with particular emphasis on applications to modern electron microscopy. Starting from a survey of fundamental phenomena, the authors introduce the most important concepts underlying modern understanding of high energy electron diffraction. Dynamical diffraction in transmission (THEED) and reflection (RHEED) geometries is treated using ageneral matrix theory, where computer programs and worked examples are provided to illustrate the concepts and to f

Surface characterization by energy distribution measurements of secondary electrons and of ion-induced electrons

International Nuclear Information System (INIS)

Bauer, H.E.; Seiler, H.

1988-01-01

Instruments for surface microanalysis (e.g. scanning electron or ion microprobes, emission electron or ion microscopes) use the current of emitted secondary electrons or of emitted ion-induced electrons for imaging of the analysed surface. These currents, integrating over all energies of the emitted low energy electrons, are however, not well suited to surface analytical purposes. On the contrary, the energy distribution of these electrons is extremely surface-sensitive with respect to shape, size, width, most probable energy, and cut-off energy. The energy distribution measurements were performed with a cylindrical mirror analyser and converted into N(E), if necessary. Presented are energy spectra of electrons released by electrons and argon ions of some contaminated and sputter cleaned metals, the change of the secondary electron energy distribution from oxidized aluminium to clean aluminium, and the change of the cut-off energy due to work function change of oxidized aluminium, and of a silver layer on a platinum sample. The energy distribution of the secondary electrons often shows detailed structures, probably due to low-energy Auger electrons, and is broader than the energy distribution of ion-induced electrons of the same object point. (author)

One electron reduction of acridine orange studied in aqueous micellar medium using pulse radiolysis technique

International Nuclear Information System (INIS)

Goel, Anjali; Guha, S.N.

1994-01-01

Absorption spectrum, decay and formation kinetics of semi reduced species formed by the reaction of hydrated electron (e aq - ) with acridine orange (AO) were evaluated in sodium lauryl sulphate (SLS) micellar medium. Fluorescence and absorption properties of AO were also studied in this micellar system. The results were compared with those in homogenous aqueous medium. (author). 2 refs., 2 figs

Detailed Monte Carlo simulation of electron elastic scattering

International Nuclear Information System (INIS)

Chakarova, R.

1994-04-01

A detailed Monte Carlo model is described which simulates the transport of electrons penetrating a medium without energy loss. The trajectory of each electron is constructed as a series of successive interaction events - elastic or inelastic scattering. Differential elastic scattering cross sections, elastic and inelastic mean free paths are used to describe the interaction process. It is presumed that the cross sections data are available and the Monte Carlo algorithm does not include their evaluation. Electrons suffering successive elastic collisions are followed until they escape from the medium or (if the absorption is negligible) their path length exceeds a certain value. The inelastic events are thus treated as absorption. The medium geometry is a layered infinite slab. The electron source could be an incident electron beam or electrons created inside the material. The objective is to obtain the angular distribution, the path length and depth distribution and the collision number distribution of electrons emitted through the surface of the medium. The model is applied successfully to electrons with energy between 0.4 and 20 keV reflected from semi-infinite homogeneous materials with different scattering properties. 16 refs, 9 figs

Medium energy hadron scattering from nuclei

International Nuclear Information System (INIS)

Ginocchio, J.N.; Wenes, G.

1986-01-01

The Glauber approximation for medium energy scattering of hadronic projectiles from nuclei is combined with the interacting boson model of nuclei to produce a transition matrix for elastic and inelastic scattering in algebraic form which includes coupling to all the intermediate states. We present closed form analytic expresions for the transition matrix elements for the three dynamical symmetries of the interacting boson model; that is for, a spherical quadrupole vibrator, a γ unstable rotor, and both prolate and oblate axially symmetric rotors. We give examples of application of this formalism to proton scattering from 154 Sm and 154 Gd. 27 refs., 5 figs., 1 tab

Local energy equation for two-electron atoms and relation between kinetic energy and electron densities

International Nuclear Information System (INIS)

March, N.H.

2002-08-01

In early work, Dawson and March [J. Chem. Phys. 81, 5850 (1984)] proposed a local energy method for treating both Hartree-Fock and correlated electron theory. Here, an exactly solvable model two-electron atom with pure harmonic interactions is treated in its ground state in the above context. A functional relation between the kinetic energy density t(r) at the origin r=0 and the electron density p(r) at the same point then emerges. The same approach is applied to the Hookean atom; in which the two electrons repel with Coulombic energy e 2 /r 12 , with r 12 the interelectronic separation, but are still harmonically confined. Again the kinetic energy density t(r) is the focal point, but now generalization away from r=0 is also effected. Finally, brief comments are added about He-like atomic ions in the limit of large atomic number. (author)

A Flexible Power Electronics Configuration for Coupling Renewable Energy Sources

Directory of Open Access Journals (Sweden)

Mattia Filippini

2015-05-01

Full Text Available A combination of series, parallel and multilevel power electronics has been investigated as a potential interface for two different types of renewable energy sources and in order to reach higher power levels. Renewable energy sources are typically dispersed in a territory, and sources, like wind and solar, allow small to medium-scale generation of electricity. The configuration investigated in this article aims at adapting the coupling solution to the specific generation characteristics of the renewable energy source to make it fit the electrical network. The configuration consists of a combination of three-phase multilevel converters and single-phase inverters, which are designed to provide flexibility, high power quality and high efficiency. A detailed analysis and simulation is performed to identify the properties in conjunction with the electrical grid requirements and the potential challenges encountered during operation. An optimized operation example of wind generation combined with solar PV generation is presented to exemplify the flexibility and benefits of the proposed configuration.

Space-time picture of relativistic propagation of medium energy hadrons through nuclei

International Nuclear Information System (INIS)

Bleszynski, M.; Jaroszewicz, T.

1985-01-01

Relativistic virtual pair creation effects in hadron-nucleus scattering at medium energies are discussed. A close analogy is found between these effects (particle propagation backwards in time) and some of noneikonal correlations to the Glauber theory, arising from particle propagation backwards in space. In multiple scattering both effects appear only for configurations involving overlapping scatterers and lead to the non-additivity of phase shifts. The proper-time path-integral formalism is found to provide an intuitive geometrical picture of these phenomena. The relativistic corrections are estimated to be of the order k/(aE/sup 2/), k being the particle momentum, E its energy, and a the target size. At medium energies they are comparable to noneikonal corrections, of order 1/(ak). Both effects vanish at high energy, when particle propagation in space-time can be described by means of geometrical optics

Inelastic collisions of medium energy atomic elements. Qualitative model of energy losses during collisions

International Nuclear Information System (INIS)

Pustovit, A.N.

2006-01-01

A new approach to the theoretical description of energy losses of atomic particle of medium energy during their interaction with the substance is proposed. The corner-stone of this approach is the supposition that all of the collision processes have inelastic nature during particle movement through the substance, while the calculation of the atomic particles braking is based on the law of their dispersion and the laws of energy and momentum conservation at the inelastic collisions. It is shown that inelastic atomic collision there are three dispersion zones for the only potential interaction with different laws, which characterize energy losses. The application conditions of this approach are determined [ru

Diffusion of Electronic Commerce in Small and Medium Enterprises

Directory of Open Access Journals (Sweden)

Robyn Lawson

2002-05-01

Full Text Available Using the Internet for electronic business has become an area of action for the Australian Government. This paper presents research results from two regional areas which indicate that while most manufacturing SMEs use email, very few are involved in elecronic commerce activities. Major barriers are concern about security and privacy of transactions, cost of consultants, and lack of IT expertise of staff. Employing people with appropriate knowledge has been added to current training methods such as on-the-job training. Results from the two regional areas are found to be consistent. Comparisons between small and medium organisations highlight some differences.

Heat sink design considerations in medium power electronic applications with long power cycles

CERN Document Server

AUTHOR|(SzGeCERN)744611; Papastergiou, Konstantinos; Thiringer, Torbjörn; Bongiorno, Massimo

2015-01-01

The aim of this work is to investigate the impact of the heat sink thickness and material, as well as, of the convection coefficient of the water cooling system on the power-electronics module thermal stressing. The heat extraction capability of different thicknesses is tested. It is concluded that the thickest heat sink results in marginally lower temperature variation at the junction level compared to the second thickest one. In the thickest heat sink case, the linear dependence of the thermal resistance on the thickness counteracts the benefit of the increased thermal capacitance. The increase in the cooling medium flow rate, which corresponds to an increase in the convection coefficient between the heat sink bottom surface and the water, can be avoided by increasing the thickness of the heat sink. In this way, the energy consumption of the cooling system is reduced. The increase in the flow rate drastically reduces the thermal stressing in the thinnest heat sink case. The increase of the heat sink thickne...

Power electronics for renewable energy systems

DEFF Research Database (Denmark)

Iov, Florin; Blaabjerg, Frede

2009-01-01

sources from the conventional, fossil (and short term) based energy sources to renewable energy resources. Another is to use high efficient power electronics in power generation, power transmission/distribution and end-user application. This paper discuss some of the most emerging renewable energy sources......, wind energy and photovoltaics, which by means of power electronics are changing from being minor energy sources to be acting as important power sources in the energy system....

Correlation functions of electronic and nuclear spins in a Heisenberg antiferromagnet semi-infinite medium

International Nuclear Information System (INIS)

Sarmento, E.F.

1981-01-01

Results are found for the dynamical correlation functions (or its corresponding Green's functions) among any combination including operator pairs of electronic and nuclear spins in an antiferromagnet semi-infinite medium, at low temperatures T [pt

Limitations of the condensed history method for low-energy electrons

International Nuclear Information System (INIS)

Martin, W.R.; Ballinger, C.T.; Rathkopf, J.A.

1991-01-01

A systematic evaluation of the conventional, condensed history electron transport methodology has been performed through comparisons with more accurate single-scatter Monte Carlo calculations. These comparisons highlight the inaccuracies associated with the condensed history method and indicate its range of validity. The condensed history method is used in codes such as MCNP4, SANDYL, ETRAN, ITS, and EGS and requires a number of restrictive assumptions about the scattering characteristics to make tractable the analytical solution to the infinite-medium transport equation. Distributions describing electron characteristics after multiple collisions (multiscatter distributions) are constructed from such solutions and serve as the heart of the condensed history codes. A two-level approach is taken to quantify the errors inherent in condensed history. First, conventional condensed history multiscattering distributions in energy and angle are compared directly with analogous distributions generated with a single-scatter Monte Carlo code. This recently developed code directly simulates individual electron interactions. Second, the conventional distributions are replaced in the condensed history code by distributions constructed via a single-scatter Monte Carlo simulation

Development of a secondary electron energy analyzer for a transmission electron microscope.

Science.gov (United States)

Magara, Hideyuki; Tomita, Takeshi; Kondo, Yukihito; Sato, Takafumi; Akase, Zentaro; Shindo, Daisuke

2018-04-01

A secondary electron (SE) energy analyzer was developed for a transmission electron microscope. The analyzer comprises a microchannel plate (MCP) for detecting electrons, a coil for collecting SEs emitted from the specimen, a tube for reducing the number of backscattered electrons incident on the MCP, and a retarding mesh for selecting the energy of SEs incident on the MCP. The detection of the SEs associated with charging phenomena around a charged specimen was attempted by performing electron holography and SE spectroscopy using the energy analyzer. The results suggest that it is possible to obtain the energy spectra of SEs using the analyzer and the charging states of a specimen by electron holography simultaneously.

Ultrafast Electron Dynamics in Solar Energy Conversion.

Science.gov (United States)

Ponseca, Carlito S; Chábera, Pavel; Uhlig, Jens; Persson, Petter; Sundström, Villy

2017-08-23

Electrons are the workhorses of solar energy conversion. Conversion of the energy of light to electricity in photovoltaics, or to energy-rich molecules (solar fuel) through photocatalytic processes, invariably starts with photoinduced generation of energy-rich electrons. The harvesting of these electrons in practical devices rests on a series of electron transfer processes whose dynamics and efficiencies determine the function of materials and devices. To capture the energy of a photogenerated electron-hole pair in a solar cell material, charges of opposite sign have to be separated against electrostatic attractions, prevented from recombining and being transported through the active material to electrodes where they can be extracted. In photocatalytic solar fuel production, these electron processes are coupled to chemical reactions leading to storage of the energy of light in chemical bonds. With the focus on the ultrafast time scale, we here discuss the light-induced electron processes underlying the function of several molecular and hybrid materials currently under development for solar energy applications in dye or quantum dot-sensitized solar cells, polymer-fullerene polymer solar cells, organometal halide perovskite solar cells, and finally some photocatalytic systems.

XRAY applied program package for calculation of electron-photon fields in the energy range of 1-1000 keV

International Nuclear Information System (INIS)

Lappa, A.V.; Khadyeva, Z.M.; Burmistrov, D.S.; Vasil'ev, O.N.

1990-01-01

The package of applied XRAY programs is intended for calculating the linear and fluctuation characteristics of photon and electron radiation fields in heterogeneous medium within 1-1000 keV energy range. The XRAY program package consists of moduli written in FORTRAN-IV and data files. 9 refs

Innovation capabilities and challenges for energy smartdevelopment in medium sized European cities

NARCIS (Netherlands)

Lindhult, Erik; Campillo, J.; Dahlquist, E.; Read, S.A.

2016-01-01

Transition towards becoming Energy smart city integrating different areas of energy production, distribution and use in a community requires a spectrum of capabilities. The paper reports on findings from the EU planning project PLEEC, involving six medium sized European cities. The purpose of the

In-medium scaling law and electron scattering from high-spin states in 208Pb

International Nuclear Information System (INIS)

Arias de Saavedra, F.; Lallena, A.M.

1994-01-01

The effects of the environment modifications in the structure of the low-lying high-spin states of 208 Pb are studied by analyzing how the in-medium scaling law works on the excitation energies, wave functions, and electron scattering form factors corresponding to these states. It is shown that the consideration of f π * in addition to the effective ρ-meson mass does not affect too much most of the states analyzed. However, some of them appear to be extremely sensitive to its inclusion in the residual nucleon-nucleon interaction. As a result, a value of m ρ * /m ρ ∼f π * /f π ∼0.91 gives a good description of the (e,e') form factors of these particular states without any quenching factor. This value is in agreement with the one found for 48 Ca in a similar analysis performed in a previous work

Secondary electrons monitor for continuous electron energy measurements in UHF linac

International Nuclear Information System (INIS)

Zimek, Zbigniew; Bulka, Sylwester; Mirkowski, Jacek; Roman, Karol

2001-01-01

Continuous energy measurements have now became obligatory in accelerator facilities devoted to radiation sterilization process. This is one of several accelerator parameters like dose rate, beam current, bean scan parameters, conveyer speed which must be recorded as it is a required condition of accelerator validation procedure. Electron energy measurements are rather simple in direct DC accelerator, where the applied DC voltage is directly related to electron energy. High frequency linacs are not offering such opportunity in electron energy measurements. The analyzing electromagnet is applied in some accelerators but that method can be used only in off line mode before or after irradiation process. The typical solution is to apply the non direct method related to control and measurements certain accelerator parameters like beam current and microwave energy pulse power. The continuous evaluation of electron energy can be performed on the base of calculation and result comparison with calibration curve

Power Electronics, Energy Harvesting and Renewable Energies Laboratory

Data.gov (United States)

Federal Laboratory Consortium — The research in the Power Electronics, Energy Harvesting and Renewable Energies Laboratory (PEHREL) is mainly focused on investigation, modeling, simulation, design,...

Secondary electron emission yield in the limit of low electron energy

CERN Document Server

Andronov, A.N.; Kaganovich, I.D.; Startsev, E.A.; Raitses, Y.; Demidov, V.I.

2013-04-22

Secondary electron emission (SEE) from solids plays an important role in many areas of science and technology.1 In recent years, there has been renewed interest in the experimental and theoretical studies of SEE. A recent study proposed that the reflectivity of very low energy electrons from solid surface approaches unity in the limit of zero electron energy2,3,4, If this was indeed the case, this effect would have profound implications on the formation of electron clouds in particle accelerators,2-4 plasma measurements with electrostatic Langmuir probes, and operation of Hall plasma thrusters for spacecraft propulsion5,6. It appears that, the proposed high electron reflectivity at low electron energies contradicts to numerous previous experimental studies of the secondary electron emission7. The goal of this note is to discuss possible causes of these contradictions.

Stability of electron-beam energy monitor for quality assurance of the electron-beam energy from radiotherapy accelerators

International Nuclear Information System (INIS)

Chida, Koichi; Zuguchi, Masayuki; Saito, Haruo; Takai, Yoshihiro; Mitsuya, Masatoshi; Sakakida, Hideharu; Yamada, Shogo; Kohzuki, Masahiro

2002-01-01

Information on electron energy is important in planning radiation therapy using electrons. The Geske 3405 electron beam energy monitor (Geske monitor, PTW Nuclear Associates, Carle Place, NY, USA) is a device containing nine ionization chambers for checking the energy of the electron beams produced by radiotherapy accelerators. We wondered whether this might increase the likelihood of ionization chamber trouble. In spite of the importance of the stability of such a quality assurance (QA) device, there are no reports on the stability of values measured with a Geske monitor. The purpose of this paper was therefore to describe the stability of a Geske monitor. It was found that the largest coefficient of variation (CV) of the Geske monitor measurements was approximately 0.96% over a 21-week period. In conclusion, the stability of Geske monitor measurements of the energy of electron beams from a linear accelerator was excellent. (author)

Power Electronics for Renewable Energy Systems

DEFF Research Database (Denmark)

Choi, U. M.; Lee, K. B.; Blaabjerg, Frede

2012-01-01

The use of renewable energy sources are increased because of the depletion of natural resources and the increasing pollution level from energy production. The wind energy and the solar energy are most widely used among the renewable energy sources. Power electronics is needed in almost all kinds...... of renewable energy system. It controls the renewable source and interfaces with the load effectively, which can be grid-connected or van work in stand-alone mode. In this presentation, overview of wind and photovoltaic energy systems are introduced. Next, the power electronic circuits behind the most common...

Benchmarking NaI(Tl) Electron Energy Resolution Measurements

International Nuclear Information System (INIS)

Mengesha, Wondwosen; Valentine, J D.

2002-01-01

A technique for validating electron energy resolution results measured using the modified Compton coincidence technique (MCCT) has been developed. This technique relies on comparing measured gamma-ray energy resolution with calculated values that were determined using the measured electron energy resolution results. These gamma-ray energy resolution calculations were based on Monte Carlo photon transport simulations, the measured NaI(Tl) electron response, a simplified cascade sequence, and the measured electron energy resolution results. To demonstrate this technique, MCCT-measured NaI(Tl) electron energy resolution results were used along with measured gamma-ray energy resolution results from the same NaI(Tl) crystal. Agreement to within 5% was observed for all energies considered between the calculated and measured gamma-ray energy resolution results for the NaI(Tl) crystal characterized. The calculated gamma-ray energy resolution results were also compared with previously published gamma-ray energy resolution measurements with good agreement (<10%). In addition to describing the validation technique that was developed in this study and the results, a brief review of the electron energy resolution measurements made using the MCCT is provided. Based on the results of this study, it is believed that the MCCT-measured electron energy resolution results are reliable. Thus, the MCCT and this validation technique can be used in the future to characterize the electron energy resolution of other scintillators and to determine NaI(Tl) intrinsic energy resolution

Low-energy electron microdosimetry of CS-137

International Nuclear Information System (INIS)

Paschoa, A.S.; Wrenn, M.E.

1980-09-01

The mass of tissue irradiated by an internal emitter depends upon the distribution of the radionuclide within the organism and the type of radiation emitted. The range (95% absorption) of low-energy electron effectively defines the sensitive volume in which the energy of the emitted electron is deposited. Accordingly, in the case of Auger electron microdosimetry of internal emitters the correct definition of the sensitive volume is of paramount importance. The amount of energy delivered by the monoenergetic electrons emitted by the decay system 137 Cs → sup(137m)Ba to spherical volumes of water-like tissue media of radii equivalent to the estimated ranges of those electrons in water is calculated and discussed as far as the variations of the estimated ranges of electrons as a function of the initial energy of emission are concerned. Although there are still many uncertainties on the actual ranges of low-energy electrons, one can state confidently that the ranges of the Auger electrons of the decay system 137 Cs → 137 sup(m) Ba → 137 Ba can be considered to be in the same order of magnitude of the diameter of a cell. The energy deposition in spherical volumes of water-like tissue media, considered equivalent to the sensitive volumes for the Auger electrons of the decay system 137 Cs → 137 sub(m) Ba → 137 Ba, range for several orders of magnitude from 10 2 to about 10 10 times higher than the energy deposition in similar media by the internal conversion electrons of this decay system. If equivalent variations of energy deposition per unit mass occur when the masses considered are cellular, and subcellular structures, then the effects into the sensitive volume should be taken into biological consideration as far as the microdosimetry of low-energy electrons (approximately equal to 10 keV) is considered, whenever there is internal localization of Auger emitters. (Author) [pt

Electron energy measurements in pulsating auroras

International Nuclear Information System (INIS)

McEwan, D.J.; Yee, E.; Whalen, B.A.; Yau, A.W.

1981-01-01

Electron spectra were obtained during two rocket flights into pulsating aurora from Southend, Saskatchewan. The first rocket launched at 1143:24 UT on February 15, 1980 flew into an aurora of background intensity 275 R of N 2 + 4278 A and showing regular pulsations with about a 17 s period. Electron spectra of Maxwellian energy distributions were observed with an average E 0 = 1.5 keV, rising to 1.8 keV during the pulsations. There was one-to-one correspondence between the electron energy modulation and the observed optical pulsations. The second rocket, launched at 1009:10 UT on February 23, flew into a diffuse auroral surface of intensity 800 R of N 2 + 4278 A and with somewhat irregular pulsations. The electron spectra were again of Maxwellian energy distribution with an average E 0 = 1.8 keV increasing to 2.1 keV during the pulsations. The results from these flights suggest that pulsating auroras occurring in the morning sector may be quite commonly excited by low energy electrons. The optical pulsations are due to periodic increases in the energy of the electrons with the source of modulation in the vicintiy of the geomagnetic equatorial plane. (auth)

Study of the giant multipole resonances especially of the isoscalar giant E2 resonance in 208Pb by medium and high energy resolution inelastic electron scattering

International Nuclear Information System (INIS)

Kuehner, G.

1982-01-01

In the nucleus 208 Pb giant multipole resonances up to excitation energies of Esub(x) = 35 MeV were looked for by medium resolution inelastic electron scattering. Twelve spectra were taken up at incident energies of E 0 = 45-65 MeV under scattering angles from upsilon = 93 0 to 165 0 . The cross sections extracted from this were analyzed by means of DWBA calculations using RPA amplitudes from a model with separable residual interaction. On the base of this analysis for the first time it could be shown that the maximum in the electron scattering cross section at Esub(x) approx.= 14 MeV can be consistently described as superposition of the Jsup(π) = 1 - , ΔT = 1 with a Jsup(π) = 0 + , ΔT = 0 giant resonance. Furthermore the spectra under backward scattering angles indicate the existence of a magnetic excitation at Esub(x) approx.= 15 MeV which is interpreted as Jsup(π) = 3 + giant resonance. Besides under forward angles a further weak excitation at Esub(x) approx.= 14.6 MeV appears which is very well compatible with Jsup(π) = 2 + . At Esub(x) = 17.5 MeV a Jsup(π) = 3 - resonance was found which recently is observed also in (α, α') experiments and therefore gets a ΔT = 0 assignment. A further resonance at Esub(x) approx.= 21 MeV has also a Jsup(π) = 3 - character but has to be partly assigned to a Jsup(π) = 1 - , ΔT = 0 excitation. At Esub(x) = 23.8 MeV a Jsup(π) = 2 + excitation was found which gets because of model predictions a ΔT = 1 assignment. (orig./HSI) [de

An accurate full-dimensional potential energy surface for H-Au(111): Importance of nonadiabatic electronic excitation in energy transfer and adsorption.

Science.gov (United States)

Janke, Svenja M; Auerbach, Daniel J; Wodtke, Alec M; Kandratsenka, Alexander

2015-09-28

We have constructed a potential energy surface (PES) for H-atoms interacting with fcc Au(111) based on fitting the analytic form of the energy from Effective Medium Theory (EMT) to ab initio energy values calculated with density functional theory. The fit used input from configurations of the H-Au system with Au atoms at their lattice positions as well as configurations with the Au atoms displaced from their lattice positions. It reproduces the energy, in full dimension, not only for the configurations used as input but also for a large number of additional configurations derived from ab initio molecular dynamics (AIMD) trajectories at finite temperature. Adiabatic molecular dynamics simulations on this PES reproduce the energy loss behavior of AIMD. EMT also provides expressions for the embedding electron density, which enabled us to develop a self-consistent approach to simulate nonadiabatic electron-hole pair excitation and their effect on the motion of the incident H-atoms. For H atoms with an energy of 2.7 eV colliding with Au, electron-hole pair excitation is by far the most important energy loss pathway, giving an average energy loss ≈3 times that of the adiabatic case. This increased energy loss enhances the probability of the H-atom remaining on or in the Au slab by a factor of 2. The most likely outcome for H-atoms that are not scattered also depends prodigiously on the energy transfer mechanism; for the nonadiabatic case, more than 50% of the H-atoms which do not scatter are adsorbed on the surface, while for the adiabatic case more than 50% pass entirely through the 4 layer simulation slab.

Nuclear scattering studies by the scattering of medium-energy electrons. Progress report, January 1, 1977--October 31, 1977

International Nuclear Information System (INIS)

Peterson, G.A.

1977-10-01

Tune-up experiments were carried out at the Bates Linear Accelerator of Middleton, Massachusetts, on the 180 0 electron scattering apparatus designed and constructed by the University of Massachusetts under contract E(11-1)-2545. This apparatus serves as adjunct equipment to the Bates dispersion-matching spectrometer. Form factors were measured for the low-lying states of 27 Al over the momentum transfer range from 0.7 to 2.6 fm -1 . A paper was published in the Physical Review on low-momentum transfer elastic electron scattering from 3 He. The 3 He rms radius was determined to be 1.89 +- 0.05 fm from measurements made at the National Bureau of Standards over the momentum transfer range-squared between 0.032 and 0.34 fm -2 . A Physical Review paper was published in November, 1977, on the results of elastic electron scattering from 25 Mg over the momentum transfer range from 0.19 to 2.56 fm -1 at both forward and backward angles. Values of all of the ground-state multipole moments of both Coulomb and magnetic character were obtained. A paper was submitted for publication on the electroexcitation of giant dipole and quadrupole resonances in 20 Ne. Electric dipole and quadrupole strength was found throughout the region from 12.5 through 25 MeV. About 65% and 100% of the energy-weighted dipole and quadrupole sum rules, respectively, were exhausted. A preliminary run was made on 42 Ca and 44 Ca at the National Bureau of Standards for an incident electron energy of 54.3 MeV and a 145 0 scattering angle in an attempt to observe f/sub 7 / 2 / to f/sub 5 / 2 / magnetic dipole transitions. A paper was composed on the 160 0 inelastic scattering of electrons from 58 Ni at momentum transfers near 2 fm -1 . Strong M8 transitions were observed which are characterized by predominantly one particle--one hole excitations characterized by the configuration

Electron energies in metals

International Nuclear Information System (INIS)

Mahan, G.D.; Tennessee Univ., Knoxville, TN

1991-01-01

The modern era of electron-electron interactions began a decade ago. Plummer's group initiated a program of using angular resolved photoemission to examine the band structure of the simple metals. Beginning with aluminum, and carrying on to sodium and potassium, they always found that the occupied energy bands were much narrower than expected. For example, the compressed energy bands for metallic potassium suggest a band effective mass of m* = 1.33m e . This should be compared to the band mass found from optical conductivity m*/m e = 1.01 ± 0.01. The discrepancy between these results is startling. It was this great difference which started my group doing calculations. Our program was two-fold. On one hand, we reanalyzed the experimental data, in order to see if Plummer's result was an experimental artifact. On the other hand, we completely redid the electron-electron self-energy calculations for simple metals, using the most modern choices of local-field corrections and vertex corrections. Our results will be reported in these lectures. They can be summarized as following: Our calculations give the same effective masses as the older calculations, so the theory is relatively unchanged; Our analysis of the experiments suggests that the recent measurements of band narrowing are an experimental artifact. 38 refs., 9 figs

Construction of energy loss function for low-energy electrons in helium

Energy Technology Data Exchange (ETDEWEB)

Dayashankar, [Bhabha Atomic Research Centre, Bombay (India). Div. of Radiation Protection

1976-02-01

The energy loss function for electrons in the energy range from 50 eV to 1 keV in helium gas has been constructed by considering separately the energy loss in overcoming the ionization threshold, the loss manifested as kinetic energy of secondary electrons and the loss in the discrete state excitations. This has been done by utilizing recent measurements of Opal et al. on the energy spectrum of secondary electrons and incorporating the experimental data on cross sections for twenty-four excited states. The present results of the energy loss function are in good agreement with the Bethe formula for energies above 500 eV. For lower energies, where the Bethe formula is not applicable, the present results should be particularly useful.

A medium energy neutron deep penetration experiment

International Nuclear Information System (INIS)

Amian, W.; Cloth, P.; Druecke, V.; Filges, D.; Paul, N.; Schaal, H.

1986-11-01

A deep penetration experiment conducted at the Los Alamos WNR facility's Spallation Neutron Target is compared with calculations using intra-nuclear-cascade and S N -transport codes installed at KFA-IRE. In the experiment medium energy reactions induced by neutrons between 15 MeV and about 150 MeV inside a quasi infinite slab of iron have been measured using copper foil monitors. Details of the experimental procedure and the theoretical methods are described. A comparison of absolute reaction rates for both experimentally and theoretically derived reactions is given. The present knowledge of the corresponding monitor reaction cross sections is discussed. (orig.)

Thick-target method in the measurement of inner-shell ionization cross-sections by low-energy electron impact

International Nuclear Information System (INIS)

An, Z.; Wu, Y.; Liu, M.T.; Duan, Y.M.; Tang, C.H.

2006-01-01

In this paper, we have studied the thick-target method for the measurements of atomic inner-shell ionization cross-section or X-ray production cross-section by keV electron impact. We find that in the processes of electron impact on the thick targets, the ratios of the characteristic X-ray yields of photoelectric ionization by bremsstrahlung to the total characteristic X-ray yields are Z-dependent and shell-dependent, and the ratios also show the weak energy-dependence. In addition, in the lower incident energy region (i.e. U < 5-6), the contribution from the rediffusion effect and the secondary electrons can be negligible. In general, the thick-target method can be appropriately applied to the measurements of atomic inner-shell ionization cross-sections or X-ray production cross-sections by electron impact for low and medium Z elements in the lower incident electron energy (i.e. U < 5-6). The experimental accuracies by the thick-target method can reach to the level equivalent or superior to the accuracies of experimental data based on the thin-target method. This thick-target method has been applied to the measurement of K-shell ionization cross-sections of Ni element by electron impact in this paper

Application of electron beam irradiation, (1). Development and application of electron beam processors

International Nuclear Information System (INIS)

Katsumura, Yosuke

1994-01-01

This paper deals with characteristics, equipment (principle and kinds), present conditions, and future issues in the application of electron beam irradiation. Characteristics of electron beams are described in terms of the following: chemical and biological effects of radiation; energy and penetrating power of electron beams; and principle and kinds of electron beam accelerator. Industrial application of electron beam irradiation has advantages of high speed procedure and producibility, less energy, avoidance of poisonous gas, and extreme reduction of organic solvents to be used. The present application of electron beam irradiation cen be divided into the following: (1) hardening of resin or coated membrane; (2) improvement of macromolecular materials; (3) environmental protection; (4) sterilization; (5) food sterilization. The present equipment for electron beam irradiation is introduced according to low energy, medium energy, and high energy equipment. Finally, future issues focuses on (1) the improvement of traceability system and development of electron dosimetric techniques and (2) food sterilization. (N.K.)

Prototyping of beam position monitor for medium energy beam transport section of RAON heavy ion accelerator

Energy Technology Data Exchange (ETDEWEB)

Jang, Hyojae, E-mail: lkcom@ibs.re.kr; Jin, Hyunchang; Jang, Ji-Ho; Hong, In-Seok [Rare Isotope Science Project, Institute for Basic Science, Daejeon (Korea, Republic of)

2016-02-15

A heavy ion accelerator, RAON is going to be built by Rare Isotope Science Project in Korea. Its target is to accelerate various stable ions such as uranium, proton, and xenon from electron cyclotron resonance ion source and some rare isotopes from isotope separation on-line. The beam shaping, charge selection, and modulation should be applied to the ions from these ion sources because RAON adopts a superconducting linear accelerator structure for beam acceleration. For such treatment, low energy beam transport, radio frequency quadrupole, and medium energy beam transport (MEBT) will be installed in injector part of RAON accelerator. Recently, development of a prototype of stripline beam position monitor (BPM) to measure the position of ion beams in MEBT section is under way. In this presentation, design of stripline, electromagnetic (EM) simulation results, and RF measurement test results obtained from the prototyped BPM will be described.

Low-energy electron collisions with metal clusters: Electron capture and cluster fragmentation

International Nuclear Information System (INIS)

Kresin, V.V.; Scheidemann, A.; Knight, W.D.

1993-01-01

The authors have carried out the first measurement of absolute cross sections for the interaction between electrons and size-resolved free metal clusters. Integral inelastic scattering cross sections have been determined for electron-Na n cluster collisions in the energy range from 0.1 eV to 30 eV. At energies ≤1 eV, cross sections increase with decreasing impact energies, while at higher energies they remain essentially constant. The dominant processes are electron attachment in the low-energy range, and collision-induced fragmentation at higher energies. The magnitude of electron capture cross sections can be quantitatively explained by the effect of the strong polarization field induced in the cluster by the incident electron. The cross sections are very large, reaching values of hundreds of angstrom 2 ; this is due to the highly polarizable nature of metal clusters. The inelastic interaction range for fragmentation collisions is also found to considerably exceed the cluster radius, again reflecting the long-range character of electron-cluster interactions. The important role played by the polarization interaction represents a bridge between the study of collision processes and the extensive research on cluster response properties. Furthermore, insight into the mechanisms of electron scattering is important for understanding production and detection of cluster ions in mass spectrometry and related processes

Positronium-alkali atom scattering at medium energies

International Nuclear Information System (INIS)

Chakraborty, Ajoy; Basu, Arindam; Sarkar, Nirmal K; Sinha, Prabal K

2004-01-01

We investigate the scattering of orthopositronium (o-Ps) atom off different atomic alkali targets (Na to Cs) at low and medium energies (up to 120 eV). Projectile-elastic and target-elastic close-coupling models have been employed to investigate the systems in addition to the static-exchange model. Elastic, excitation and total cross sections have been reported for all four systems. The magnitude of the alkali excitation cross section increases with increasing atomic number of the target atom while the position of the peak value shifts towards lower incident energies. The magnitudes of the Ps excitation and ionization cross sections increase steadily with atomic number with no change in the peak position. The reported results show regular behaviour with increasing atomic number of the target atom. Scattering parameters for the Ps-Rb and Ps-Cs systems are being reported for the first time

Medium energy nuclear physics research

International Nuclear Information System (INIS)

Peterson, G.A.; Dubach, J.F.; Hicks, R.S.; Miskimen, R.A.

1991-06-01

This report discusses research conducted on the following topics: transverse from factors of 117 Sn; elastic magnetic electron scattering from 13 C at Q 2 = 1 GeV 2 /c 2 ; a re-analysis of 13 C elastic scattering; deuteron threshold electrodisintegration; measurement of the elastic magnetic form factor of 3 He at high momentum transfer; coincidence measurement of the D(e,e'p) cross-section at low excitation energy and high momentum transfer; measurement of the quadrupole contribution to the N → Δ excitation; measurement of the x-, Q 2 -, and A-dependence of R = σ L /σ T ; the PEGASYS project; PEP beam-gas event analysis; plans for other experiments at SLAC: polarized electron scattering on polarized nuclei; experiment PR-89-015: study of coincidence reactions in the dip and delta-resonance regions; experiment PR-89-031: multi-nulceon knockout using the CLAS detector; drift chamber tests; a memorandum of understanding and test experiments; photoprotons from 10 B; and hadronic electroproduction at LEP

Compact multi-energy electron linear accelerators

International Nuclear Information System (INIS)

Tanabe, E.; Hamm, R.W.

1985-01-01

Two distinctly different concepts that have been developed for compact multi-energy, single-section, standing-wave electron linear accelerator structures are presented. These new concepts, which utilize (a) variable nearest neighbor couplings and (b) accelerating field phase switching, provide the capability of continuously varying the electron output energy from the accelerator without degrading the energy spectrum. These techniques also provide the means for continuously varying the energy spectrum while maintaining a given average electron energy, and have been tested successfully with several accelerators of length from 0.1 m to 1.9 m. Theoretical amd experimental results from these accelerators, and demonstrated applications of these techniques to medical and industrial linear accelerator technology will be described. In addition, possible new applications available to research and industry from these techniques are presented. (orig.)

Partial cross sections of helium satellites at medium photon energies

Energy Technology Data Exchange (ETDEWEB)

Wehlitz, R.; Sellin, I.A. [Univ. of Tennessee, Knoxville, TN (United States); Hemmers, O. [Univ. of Nevada, Las Vegas, NV (United States)] [and others

1997-04-01

Still of current interest is the important role of single ionization with excitation compared to single ionization alone. The coupling between the electrons and the incoming photon is a single-particle operator. Thus, an excitation in addition to an ionization, leading to a so-called satellite line in a photoelectron spectrum, is entirely due to electron-electron interaction and probes the electron correlation in the ground and final state. Therefore the authors have undertaken the study of the intensity of helium satellites He{sup +}nl (n = 2 - 6) relative to the main photoline (n = 1) as a function of photon energy at photon energies well above threshold up to 900 eV. From these results they could calculate the partial cross-sections of the helium satellites. In order to test the consistency of their satellite-to-1s ratios with published double-to-single photoionization ratios, the authors calculated the double-to-single photoionization ratio from their measured ratios using the theoretical energy-distribution curves of Chang and Poe and Le Rouzo and Dal Cappello which proved to be valid for photon energies below 120 eV. These calculated double-to-single ionization ratios agree fairly well with recent ion measurements. In the lower photon energy range the authors ratios agree better with the ratios of Doerner et al. while for higher photon energies the agreement is better with the values of Levin et al.

Partial cross sections of helium satellites at medium photon energies

International Nuclear Information System (INIS)

Wehlitz, R.; Sellin, I.A.; Hemmers, O.

1997-01-01

Still of current interest is the important role of single ionization with excitation compared to single ionization alone. The coupling between the electrons and the incoming photon is a single-particle operator. Thus, an excitation in addition to an ionization, leading to a so-called satellite line in a photoelectron spectrum, is entirely due to electron-electron interaction and probes the electron correlation in the ground and final state. Therefore the authors have undertaken the study of the intensity of helium satellites He + nl (n = 2 - 6) relative to the main photoline (n = 1) as a function of photon energy at photon energies well above threshold up to 900 eV. From these results they could calculate the partial cross-sections of the helium satellites. In order to test the consistency of their satellite-to-1s ratios with published double-to-single photoionization ratios, the authors calculated the double-to-single photoionization ratio from their measured ratios using the theoretical energy-distribution curves of Chang and Poe and Le Rouzo and Dal Cappello which proved to be valid for photon energies below 120 eV. These calculated double-to-single ionization ratios agree fairly well with recent ion measurements. In the lower photon energy range the authors ratios agree better with the ratios of Doerner et al. while for higher photon energies the agreement is better with the values of Levin et al

Injection system of teh SSC Medium Energy Booster

International Nuclear Information System (INIS)

Mao, N.; Gerig, R.; McGill, J.; Brown, K.

1994-04-01

The Medium Energy Booster (MEB) is the third of the SSCL accelerators and the largest of the resistive magnet synchrotrons. It accelerates protons from an injection momentum of 12 GeV/c to a top momentum of 200 GeV/c. A beam injection system has been designed to inject the beam transferred from the Low Energy Booster onto the MEB closed orbit in the MEB injection insertion region. The beam is injected via a vertical bending Lambertson septum magnet and a horizontal kicker with appropriate matching and very little beam loss and emittance dilution. The beam optics of the injection system is described in this paper. The required parameters of the Lambertson septum magnet and the injection kicker are given

Dependence of electron inelastic mean free paths on electron energy and materials at low energy region, 1

International Nuclear Information System (INIS)

Tanuma, Shigeo; Powell, C.J.; Penn, D.R.

1990-01-01

We have proposed a general formula of electron inelastic mean free path (IMFP) to describe the calculated IMFPs over the 50-2000 eV energy range based on the Inokuti's modified Bethe formula for the inelastic scattering cross section. The IMFPs for 50-2000 eV electrons in 27 elements were calculated using Penn's algorithm. The IMFP dependence on electron energy in the range 50-200 eV varies considerably from material to material. These variations are associated with substantial differences in the electron energy-loss functions amongst the material. We also found that the modified Bethe formula by Inokuti could be fitted to the calculated IMFPs in the range 50-2000 eV within 3% relative error. (author)

Energy dependent response of plastic scintillation detectors to photon radiation of low to medium energy.

Science.gov (United States)

Ebenau, Melanie; Radeck, Désirée; Bambynek, Markus; Sommer, Holger; Flühs, Dirk; Spaan, Bernhard; Eichmann, Marion

2016-08-01

Plastic scintillation detectors are promising candidates for the dosimetry of low- to medium-energy photons but quantitative knowledge of their energy response is a prerequisite for their correct use. The purpose of this study was to characterize the energy dependent response of small scintillation detectors (active volume <1 mm(3)) made from the commonly used plastic scintillator BC400. Different detectors made from BC400 were calibrated at a number of radiation qualities ranging from 10 to 280 kV and at a (60)Co beam. All calibrations were performed at the Physikalisch-Technische Bundesanstalt, the National Metrology Institute of Germany. The energy response in terms of air kerma, dose to water, and dose to the scintillator was determined. Conversion factors from air kerma to dose to water and to dose to the scintillator were derived from Monte Carlo simulations. In order to quantitatively describe the energy dependence, a semiempirical model known as unimolecular quenching or Birks' formula was fitted to the data and from this the response to secondary electrons generated within the scintillator material BC400 was derived. The detector energy response in terms of air kerma differs for different scintillator sizes and different detector casings. It is therefore necessary to take attenuation within the scintillator and in the casing into account when deriving the response in terms of dose to water from a calibration in terms of air kerma. The measured energy response in terms of dose to water for BC400 cannot be reproduced by the ratio of mean mass energy-absorption coefficients for polyvinyl toluene to water but shows evidence of quenching. The quenching parameter kB in Birks' formula was determined to be kB = (12.3 ± 0.9) mg MeV(-1) cm(-2). The energy response was quantified relative to the response to (60)Co which is the common radiation quality for the calibration of therapy dosemeters. The observed energy dependence could be well explained with the

Energy dependent response of plastic scintillation detectors to photon radiation of low to medium energy

Energy Technology Data Exchange (ETDEWEB)

Ebenau, Melanie, E-mail: melanie.ebenau@tu-dortmunde.de; Sommer, Holger; Spaan, Bernhard; Eichmann, Marion [Fakultät Physik, Technische Universität Dortmund, Otto-Hahn Str. 4a, 44221 Dortmund (Germany); Radeck, Désirée; Bambynek, Markus [Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig (Germany); Flühs, Dirk [Universitätsklinikum Essen, Hufelandstr. 55, 45147 Essen (Germany)

2016-08-15

Purpose: Plastic scintillation detectors are promising candidates for the dosimetry of low- to medium-energy photons but quantitative knowledge of their energy response is a prerequisite for their correct use. The purpose of this study was to characterize the energy dependent response of small scintillation detectors (active volume <1 mm{sup 3}) made from the commonly used plastic scintillator BC400. Methods: Different detectors made from BC400 were calibrated at a number of radiation qualities ranging from 10 to 280 kV and at a {sup 60}Co beam. All calibrations were performed at the Physikalisch-Technische Bundesanstalt, the National Metrology Institute of Germany. The energy response in terms of air kerma, dose to water, and dose to the scintillator was determined. Conversion factors from air kerma to dose to water and to dose to the scintillator were derived from Monte Carlo simulations. In order to quantitatively describe the energy dependence, a semiempirical model known as unimolecular quenching or Birks’ formula was fitted to the data and from this the response to secondary electrons generated within the scintillator material BC400 was derived. Results: The detector energy response in terms of air kerma differs for different scintillator sizes and different detector casings. It is therefore necessary to take attenuation within the scintillator and in the casing into account when deriving the response in terms of dose to water from a calibration in terms of air kerma. The measured energy response in terms of dose to water for BC400 cannot be reproduced by the ratio of mean mass energy-absorption coefficients for polyvinyl toluene to water but shows evidence of quenching. The quenching parameter kB in Birks’ formula was determined to be kB = (12.3 ± 0.9) mg MeV{sup −1} cm{sup −2}. Conclusions: The energy response was quantified relative to the response to {sup 60}Co which is the common radiation quality for the calibration of therapy dosemeters. The

Monte Carlo simulation of energy deposition by low-energy electrons in molecular hydrogen

Science.gov (United States)

Heaps, M. G.; Furman, D. R.; Green, A. E. S.

1975-01-01

A set of detailed atomic cross sections has been used to obtain the spatial deposition of energy by 1-20-eV electrons in molecular hydrogen by a Monte Carlo simulation of the actual trajectories. The energy deposition curve (energy per distance traversed) is quite peaked in the forward direction about the entry point for electrons with energies above the threshold of the electronic states, but the peak decreases and broadens noticeably as the electron energy decreases below 10 eV (threshold for the lowest excitable electronic state of H2). The curve also assumes a very symmetrical shape for energies below 10 eV, indicating the increasing importance of elastic collisions in determining the shape of the curve, although not the mode of energy deposition.

Low energy electron scattering from fuels

International Nuclear Information System (INIS)

Lopes, M. Cristina A.; Silva, Daniel G.M.; Coelho, Rafael F.; Duque, Humberto V.; Santos, Rodrigo R. dos; Ribeiro, Thiago M.

2011-01-01

Full text. Accurate and precise values of absolute total cross section (TCS) represent important information in many scientific and technological applications. In our case, for example, we are motivated to provide such information for electron-fuel collision processes which are specifically relevant to modeling spark ignition in alcohol-fuelled internal combustion engines. Many electron scattering TCS measurements are presently available for a diverse range of atomic and molecular targets. However, lack of data for important bio-molecular targets still remains. Disagreements between the available TCS data for the alcohols have prompted several studies of electron scattering collision of slow electrons with these molecules which are currently important in applications as bio- fuels. This relevance, which has attracted much attention, has been one of the subjects of a recent collaboration between experimental and theoretical groups in the USA and Brazil. Recently this collaboration reported first measurements and calculations of differential cross sections for elastic low-energy (rotationally unresolved) electron scattering by several primary alcohols. In this work we address methanol and ethanol TCSs at low energy range and report additional studies of resonant structure in ethanol using the detection of metastable states produced by electron impact excitation with high energy resolution. We have recently constructed a TCS apparatus in our laboratory at Universidade Federal de Juiz de Fora, Brazil, based on the well-known linear transmission technique. The experimental setup is based on the measurement of the attenuation of a collimated electron beam through a gas cell containing the atoms or molecules to be studied at a given pressure. It consists essentially of an electron gun, a gas cell and an electron energy analyzer composed of an array of decelerating electrostatic lenses, a cylindrical dispersive 127o analyzer and a Faraday cup. To our knowledge, there exist

Low energy electron scattering from fuels

Energy Technology Data Exchange (ETDEWEB)

Lopes, M. Cristina A.; Silva, Daniel G.M.; Coelho, Rafael F.; Duque, Humberto V.; Santos, Rodrigo R. dos; Ribeiro, Thiago M. [Universidade Federal de Juiz de Fora (UFJF), MG (Brazil). Dept. de Fisica; Yates, Brent; Hong, Ling; Khakoo, Murtadha A. [California State University at Fullerton, CA (US). Physics Department; Bettega, Marcio H.F. [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil). Dept. de Fisica; Costa, Romarly F. da [Universidade Federal do ABC (UFABC), Santo Andre, SP (Brazil). Centro de Ciencias Naturais e Humanas; Lima, Marco A.P. [Laboratorio Nacional de Ciencia e Tecnologia do Bioetanol (CTBE/CNPEM), Campinas, SP (Brazil)

2011-07-01

Full text. Accurate and precise values of absolute total cross section (TCS) represent important information in many scientific and technological applications. In our case, for example, we are motivated to provide such information for electron-fuel collision processes which are specifically relevant to modeling spark ignition in alcohol-fuelled internal combustion engines. Many electron scattering TCS measurements are presently available for a diverse range of atomic and molecular targets. However, lack of data for important bio-molecular targets still remains. Disagreements between the available TCS data for the alcohols have prompted several studies of electron scattering collision of slow electrons with these molecules which are currently important in applications as bio- fuels. This relevance, which has attracted much attention, has been one of the subjects of a recent collaboration between experimental and theoretical groups in the USA and Brazil. Recently this collaboration reported first measurements and calculations of differential cross sections for elastic low-energy (rotationally unresolved) electron scattering by several primary alcohols. In this work we address methanol and ethanol TCSs at low energy range and report additional studies of resonant structure in ethanol using the detection of metastable states produced by electron impact excitation with high energy resolution. We have recently constructed a TCS apparatus in our laboratory at Universidade Federal de Juiz de Fora, Brazil, based on the well-known linear transmission technique. The experimental setup is based on the measurement of the attenuation of a collimated electron beam through a gas cell containing the atoms or molecules to be studied at a given pressure. It consists essentially of an electron gun, a gas cell and an electron energy analyzer composed of an array of decelerating electrostatic lenses, a cylindrical dispersive 127o analyzer and a Faraday cup. To our knowledge, there exist

Influence of high energy electrons on ECRH in LHD

Directory of Open Access Journals (Sweden)

Ogasawara S.

2012-09-01

Full Text Available The central bulk electron temperature of more than 20 keV is achieved in LHD as a result of increasing the injection power and the lowering the electron density near 2 × 1018 m−3. Such collision-less regime is important from the aspect of the neoclassical transport and also the potential structure formation. The presences of appreciable amount of high energy electrons are indicated from hard X-ray PHA, and the discrepancy between the stored energy and kinetic energy estimated from Thomson scattering. ECE spectrum are also sensitive to the presence of high energy electrons and discussed by solving the radiation transfer equation. The ECRH power absorption to the bulk and the high energy electrons are dramatically affected by the acceleration and the confinement of high energy electrons. The heating mechanisms and the acceleration process of high energy electrons are discussed by comparing the experimental results and the ray tracing calculation under assumed various density and mean energy of high energy electrons.

Treatment of foods with 'soft-electrons' (low-energy electrons)

International Nuclear Information System (INIS)

Hayashi, Toru; Todoriki, Setsuko

2003-01-01

Electrons with energies of 300 keV or lower were defined as soft-electrons'. Soft-electrons can eradicate microorganisms residing on the surface of grains, pulses, spices, dehydrated vegetables, tea leaves and seeds, and reduce their microbial loads to levels lower than 10 CFU/g with little quality deterioration. Soft-electrons can inactivate insect pests infesting grains and pulses and inhibit sprouting of potatoes. (author)

Microscopic optical potential at medium energies

International Nuclear Information System (INIS)

Malecki, A.

1979-01-01

The problems concerning a microscopic optical model for the elastic nuclear collisions at medium energies are discussed. We describe the method for constructing the optical potential which makes use of the particular properties of quantum scattering in the eikonal limit. The resulting potential is expressed in terms of the nuclear wave functions and the nucleon-nucleon scattering amplitudes. This potential has a dynamic character since by including the effects of multiple scattering it allows for the possibility of intermediate excitations of the projectile and target nuclei. The use of the potential in the exact wave equation accounts for the most important mechanisms present in the collisions between composite particles. The microscopic optical model was successfully applied in the analysis of elastic scattering of protons and α-particles on atomic nuclei in the energy range of 300-1000 MeV/nucleon. The dynamic optical potential in this case represents a considerable improvement over the eikonal Glauber model and the static optical potential of Watson. The possibilities to extend the microscopic description of the proton-nucleus interaction by considering the spin dependence of the elementary amplitude and the Majorana exchange effects were investigated. (author)

Equation satisfied by electron-electron mutual Coulomb repulsion energy density functional

OpenAIRE

Joubert, Daniel P.

2011-01-01

The electron-electron mutual Coulomb repulsion energy density functional satisfies an equation that links functionals and functional derivatives at N-electron and (N-1)-electron densities for densities determined from the same adiabatic scaled external potential for the N-electron system.

On the polarized beam acceleration in medium energy synchrotrons

International Nuclear Information System (INIS)

Lee, S.Y.

1992-01-01

This lecture note reviews physics of spin motion in a synchrotron, spin depolarization mechanisms of spin resonances, and methods of overcoming the spin resonances during acceleration. Techniques used in accelerating polarized ions in the low/medium energy synchrotrons, such as the ZGS, the AGS, SATURNE, and the KEK PS and PS Booster are discussed. Problems related to polarized proton acceleration with snakes or partial snake are also examined

On the polarized beam acceleration in medium energy synchrotrons

Energy Technology Data Exchange (ETDEWEB)

Lee, S.Y.

1992-12-31

This lecture note reviews physics of spin motion in a synchrotron, spin depolarization mechanisms of spin resonances, and methods of overcoming the spin resonances during acceleration. Techniques used in accelerating polarized ions in the low/medium energy synchrotrons, such as the ZGS, the AGS, SATURNE, and the KEK PS and PS Booster are discussed. Problems related to polarized proton acceleration with snakes or partial snake are also examined.

Intercomparison of medium-energy neutron attenuation in iron and concrete

International Nuclear Information System (INIS)

Hirayama, H.

1999-01-01

Neutron attenuation of medium energy below 1 GeV has not been well understood until now. It is desired to obtain common agreements concerning the behaviours of neutrons inside various materials. This is necessary in order to agree on definitions of the attenuation length, which is very important for shielding calculations involving high energy accelerators. As one attempt, it was proposed by Japanese attendants of SATIF-2 to compare the attenuation of medium-energy neutrons inside iron and concrete shields between various computer codes and data, and was cited as a suitable action for SATIF. The first results from three groups were presented at SATIF-3. It has become clear that neutrons above 20 MeV are important for understanding the attenuation inside materials and that the geometry, planar or spherical, does not affect the results very much. Considering the CPU times required for Monte Carlo calculations and this result, revised problems to be calculated were prepared by the Japanese Working Group and sent to the participants of this action. The geometry is only plane, and calculations are required only for neutrons above 20 MeV. The secondary neutrons from high energy protons, which were calculated by H. Nakashima, are also included in the problem. The results from four groups were sent to the organizer at the end of August. This paper presents a comparison between groups concerning the attenuation length together with the neutron spectrum and the future themes which come from this intercomparison. (author)

Short- and medium-range order of atomic structure and electronic properties of arsenic salinide and sulphide amorphous films

International Nuclear Information System (INIS)

Sarsembinov, Sh.Sh.; Prikhodko, O.Yu.; Ryaguzov, A.P.; Maksimova, S.Ya.; Ushanov, V.Zh.

2004-01-01

Full text: The relationship between short- and medium-range order of atomic structure and electronic properties is the object of invariable attention of disordered matter physics. This problem is the most important for non-crystalline semiconductors, and specifically for chalcogenide glassy semiconductors (ChGS) films due to low co-ordination of atoms, which leads to lability of their structure. In this report we present results of atomic structure, electric, optical properties and carrier drift investigation in amorphous films of As 2 Se 3 and As 2 S 3 prepared by thermal evaporation in a vacuum (TE films) and by RF ion-plasma sputtering (RF films). These techniques strongly differing in the conditions of substance vaporization and condensation atoms on a substrate. The short- and medium-range order of the films atomic structure has been studied by X-ray diffraction analysis using the CuKα radiation (λ=1.5418 Angstrom) and by Raman spectroscopy. Raman spectra were measured at room temperature on Perkin-Elmer Spectrum GX Raman FT-IR Spectrometer (180 deg. backscattering). Vibrational modes were excited vertically polarized light of DPY Nd:YAG laser (1.064 μm). The radii of the first and second coordination spheres, number of the nearest neighbours of As and Se (S) atoms in the first coordination sphere, dimension of the medium-range order domain and 'quasi-period' in that region have been determined for the studied samples. The identification of the structural units in matrix of the film has been carried out, too. It is established that the films prepared by different methods have differences in the parameters of short- and medium range orders. It follows from the comparative analysis of Raman spectra that spectrum of RF films is significantly more complex than that of glass and TE films. The matrix of RF films contains, along with the structural units AsSe 3/2 (AsS 3/2 ) inherent in TE films and glass, other structural units with As and Se (S) excess. It may be

Computer simulation program for medium-energy ion scattering and Rutherford backscattering spectrometry

Science.gov (United States)

Nishimura, Tomoaki

2016-03-01

A computer simulation program for ion scattering and its graphical user interface (MEISwin) has been developed. Using this program, researchers have analyzed medium-energy ion scattering and Rutherford backscattering spectrometry at Ritsumeikan University since 1998, and at Rutgers University since 2007. The main features of the program are as follows: (1) stopping power can be chosen from five datasets spanning several decades (from 1977 to 2011), (2) straggling can be chosen from two datasets, (3) spectral shape can be selected as Gaussian or exponentially modified Gaussian, (4) scattering cross sections can be selected as Coulomb or screened, (5) simulations adopt the resonant elastic scattering cross section of 16O(4He, 4He)16O, (6) pileup simulation for RBS spectra is supported, (7) natural and specific isotope abundances are supported, and (8) the charge fraction can be chosen from three patterns (fixed, energy-dependent, and ion fraction with charge-exchange parameters for medium-energy ion scattering). This study demonstrates and discusses the simulations and their results.

Can low energy electrons affect high energy physics accelerators?

CERN Document Server

Cimino, R; Furman, M A; Pivi, M; Ruggiero, F; Rumolo, Giovanni; Zimmermann, Frank

2004-01-01

The properties of the electrons participating in the build up of an electron cloud (EC) inside the beam-pipe have become an increasingly important issue for present and future accelerators whose performance may be limited by this effect. The EC formation and evolution are determined by the wall-surface properties of the accelerator vacuum chamber. Thus, the accurate modeling of these surface properties is an indispensible input to simulation codes aimed at the correct prediction of build-up thresholds, electron-induced instability or EC heat load. In this letter, we present the results of surface measurements performed on a prototype of the beam screen adopted for the Large Hadron Collider (LHC), which presently is under construction at CERN. We have measured the total secondary electron yield (SEY) as well as the related energy distribution curves (EDC) of the secondary electrons as a function of incident electron energy. Attention has been paid, for the first time in this context, to the probability at whic...

Transient Exciplex Formation Electron Transfer Mechanism

Directory of Open Access Journals (Sweden)

Michael G. Kuzmin

2011-01-01

Full Text Available Transient exciplex formation mechanism of excited-state electron transfer reactions is analyzed in terms of experimental data on thermodynamics and kinetics of exciplex formation and decay. Experimental profiles of free energy, enthalpy, and entropy for transient exciplex formation and decay are considered for several electron transfer reactions in various solvents. Strong electronic coupling in contact pairs of reactants causes substantial decrease of activation energy relative to that for conventional long-range ET mechanism, especially for endergonic reactions, and provides the possibility for medium reorganization concatenated to gradual charge shift in contrast to conventional preliminary medium and reactants reorganization. Experimental criteria for transient exciplex formation (concatenated mechanism of excited-state electron transfer are considered. Available experimental data show that this mechanism dominates for endergonic ET reactions and provides a natural explanation for a lot of known paradoxes of ET reactions.

Förster resonance energy transfer between acridinediones and selected fluorophores—Medium dependence

Energy Technology Data Exchange (ETDEWEB)

Krishnaveni, R. [National Centre for Ultrafast Processes, University of Madras, Taramani Campus, Chennai-600113 (India); Ramamurthy, P., E-mail: prm60@hotmail.com [National Centre for Ultrafast Processes, University of Madras, Taramani Campus, Chennai-600113 (India)

2013-06-15

We report highly efficient Förster resonance energy transfer process between acridinedione dyes and basic fluorophores. FRET between free and β-cyclodextrin modified acridinediones as donors and fluorophoric dyes like safranine as acceptor were investigated in an alcoholic medium, polymer solution and a polymeric film. Efficiency of the processes were experimentally found by steady-state and time-resolved experiments for different donor and acceptor combinations. The associated spectral parameters viz., R{sup 0}, J(λ) were calculated, the Stern–Volmer relations based on fluorescence intensity and lifetime were constructed and the rates of energy transfer were calculated. The results indicated that the dominant mechanism responsible for the excitation energy transfer is that of resonance transfer due to long range dipole–dipole interaction and the process was found to be highly efficient when the medium was a constrained one as in the case of a polymeric film. A multifold enhancement in efficiency of energy transfer was also observed when the donor was a modified acridinedione when compared to a free acridinedione. The reason is attributed to the effective binding of the acceptor into the cavity of β-cyclodextrin. Highlights: ► FRET between acridinediones and fluorophoric acceptors were investigated. ► FRET analysis was carried out in methanol, a 5% PVA solution and in PVA matrix. ► FRET efficiency was maximum when the medium was PVA matrix. ► FRET efficiency was also more when β-CD modified ADR is used as the donor. ► Efficiency enhancement is due to the inclusion of acceptor into the cavity of β-CD.

Analytical approximation of the nanoscale dose distribution in an irradiated medium with an embedded nanoparticle

International Nuclear Information System (INIS)

Chernov, V; Barboza-Flores, M; Chernov, G

2012-01-01

In this work we propose an analytical approach describing the dose distribution around a NP embedded in a medium. The approach describes the following sequence of events: The homogenous and isotropic creation of secondary electrons under incident photon fluence; travel of the created electrons toward the NP surface and their escaping from the NP with different energies and angles; deposition of energy in surrounding medium. The radial dose distribution around the NP was found as the average energy deposited by the escaped electrons in a spherical shell at a distance r from the NP center normalized to its mass. The continuous slowing down approximation and the assumption that created electrons travel in a straight-line path were used. As result, a set of analytical expressions describing the dose distribution was derived. The expressions were applied to the calculation of the dose distribution around spherical gold NPs of different size embedded in water. It was shown that the dose distribution is close to the 1/r 2 dependence and practically independent of the NP radius.

Workshop on Hydrogen Storage and Generation for Medium-Power and -Energy Applications

National Research Council Canada - National Science Library

Matthews, Michael

1998-01-01

This report summarizes the Workshop on Hydrogen Storage and Generation Technologies for Medium-Power and -Energy Applications which was held on April 8-10, 1997 at the Radisson Hotel Orlando Airport in Orlando, Florida...

Transport of secondary electrons and reactive species in ion tracks

Science.gov (United States)

Surdutovich, Eugene; Solov'yov, Andrey V.

2015-08-01

The transport of reactive species brought about by ions traversing tissue-like medium is analysed analytically. Secondary electrons ejected by ions are capable of ionizing other molecules; the transport of these generations of electrons is studied using the random walk approximation until these electrons remain ballistic. Then, the distribution of solvated electrons produced as a result of interaction of low-energy electrons with water molecules is obtained. The radial distribution of energy loss by ions and secondary electrons to the medium yields the initial radial dose distribution, which can be used as initial conditions for the predicted shock waves. The formation, diffusion, and chemical evolution of hydroxyl radicals in liquid water are studied as well. COST Action Nano-IBCT: Nano-scale Processes Behind Ion-Beam Cancer Therapy.

Energy losses (gains) of massive coloured particles in stochastic colour medium

International Nuclear Information System (INIS)

Leonidov, A.; Rossijskaya Akademiya Nauk, Moscow

1995-01-01

The propagation of massive coloured particles in stochastic background chromoelectric field is studied using the semiclassical equations of motion. Depending on the nature of the stochastic background we obtain the formulae for the energy losses of heavy coloured projectile in nonperturbative hadronic medium and for the energy gains in the stochastic field present, e.g., in the turbulent plasma. The result appears to be significantly dependent on the form of the correlation function of stochastic external field. (orig.)

Electronic energy distribution function at high electron swarm energies in neon

International Nuclear Information System (INIS)

Brown, K.L.; Fletcher, J.

1995-01-01

Electron swarms moving through a gas under the influence of an applied electric field have been extensively investigated. Swarms at high energies, as measured by the ratio of the applied field to the gas number density, E/N, which are predominant in many applications have, in general, been neglected. Discharges at E/N in the range 300 0 < 133 Pa using a differentially pumped vacuum system in which the swarm electrons are extracted from the discharge and energy analysed in both a parallel plate retarded potential analyser and a cylindrical electrostatic analyser. Both pre-breakdown and post-breakdown discharges have been studied. Initial results indicate that as the discharge traverses breakdown no sudden change in the nature of the discharge occurs and that the discharge can be described by both a Monte Carlo simulation and by a Boltzmann treatment given by Phelps et al. (1987). 18 refs., 8 figs

Anomalous resonance-radiation energy-transfer rate in a scattering dispersive medium

International Nuclear Information System (INIS)

Shekhtman, V.L.

1992-01-01

This paper describes a generalization of the concept of group velocity as an energy-transfer rate in a dispersive medium with complex refractive index when the polaritons, which are energy carriers, undergo scattering, in contrast to the classical concept of the group velocity of free polaritons (i.e., without scattering in the medium). The concept of delay time from quantum multichannel-scattering, theory is used as the fundamental concept. Based on Maxwell's equations and the new mathematical Φ-function method, a consistent conceptual definition of group velocity in terms of the ratio of the coherent-energy flux density to the coherent-energy density is obtained for the first time, and a critical analysis of the earlier (Brillouin) understanding of energy-transfer rate is given in the light of radiation-trapping theory and the quantum theory of resonance scattering. The role of generalized group velocity is examined for the interpretation of the phenomenon of multiple resonance scattering, or radiation diffusion. The question of causality for the given problem is touched upon; a new relationship is obtained, called the microcausality condition, which limits the anomalous values of group velocity by way of the indeterminacy principle and the relativistic causality principle for macroscopic time intervals directly measurable in experiment, whereby attention is focused on the connection of the given microcausality condition and the well-known Wigner inequality for the time delay of spherical waves. 22 refs

Depth sectioning using electron energy loss spectroscopy

International Nuclear Information System (INIS)

D'Alfonso, A J; Findlay, S D; Allen, L J; Cosgriff, E C; Kirkland, A I; Nellist, P D; Oxley, M P

2008-01-01

The continued development of electron probe aberration correctors for scanning transmission electron microscopy has enabled finer electron probes, allowing atomic resolution column-by-column electron energy loss spectroscopy. Finer electron probes have also led to a decrease in the probe depth of focus, facilitating optical slicing or depth sectioning of samples. The inclusion of post specimen aberration corrected image forming lenses allows for scanning confocal electron microscopy with further improved depth resolution and selectivity. We show that in both scanning transmission electron microscopy and scanning confocal electron microscopy geometries, by performing a three dimensional raster scan through a specimen and detecting electrons scattered with a characteristic energy loss, it will be possible to determine the location of isolated impurities embedded within the bulk.

A gas-silicon telescope for medium-heavy ion detection

International Nuclear Information System (INIS)

Kozik, T.; Buschmann, J.; Neudold, M.

1985-12-01

A ΔE-E telescope for the identification of medium-heavy ions is presented. The specific energy loss is measured with a gas ionization chamber, and the residual energy is determined with a silicon surface barrier detector. The main features of the collecting electrical field and the timing properties of the device are discussed under theoretical aspects. The gas supply system, its electronic control unit, and the operating procedures are described. Two different versions of the coincidence electronics are shown. The experimental performance of the gas-silicon telescope is demonstrated and is found to be close to the best Z-resolution which can be obtained with this technique. (orig.) [de

Microscopic study of elastic and inelastic ALPHA-nucleus scattering at medium energies

International Nuclear Information System (INIS)

Dao Tien Khoa; Hoang Si Than; Do Cong Cuong; Ngo Van Luyen; Nguyen Ngoc Quynh; Nguyen Tuan Anh

2007-01-01

Analyses of the inelastic α + 12 C scattering at medium energies have indicated that the strength of the Hoyle state (the isoscalar O 2 + excitation at 7.65 MeV in 12 C) seems to exhaust only 7 to 9% of the monopole energy weighted sum rule (EWSR), compared to about 15% of the EWSR extracted from inelastic electron scattering data. The full monopole transition strength predicted by realistic microscopic α-cluster models of the Hoyle state can be shown to exhaust up to 22% of the EWSR. To explore the missing monopole strength in the inelastic α + 12 C scattering, we have performed a fully microscopic folding model analysis of the inelastic α + 12 C scattering at E lab =104 to 240 MeV using the 3-α resonating group wave function of the Hoyle state obtained by Kamimura, and a complex density-dependent M3Y interaction newly parametrized based on the Brueckner Hartree Fock results for nuclear matter. Our folding model analysis has shown consistently that the missing monopole strength of the Hoyle state is not associated with the uncertainties in the analysis of the α + 12 C scattering, but is most likely due to the short lifetime and weakly bound structure of this state which significantly enhances absorption in the exit α + 12 C * (O 2 + ) channel. (author)

Description of inelastic nucleus-nucleus interactions at medium energy using dual parton model

International Nuclear Information System (INIS)

Polanski, A.; Shmakov, S.Yu.; Uzhinskij, V.V.

1989-01-01

It is shown that the dual parton model taking into account the processes of diffraction dissociation to the low mass states and finite energy corrections to the asymptotic Abramovski-Gribov-Kancheli cutting rules allows satisfactory description of existing experimental data on hadron-nucleus and nucleus-nucleus interactions at medium energy. (orig.)

Energy-filtered real- and k-space secondary and energy-loss electron imaging with Dual Emission Electron spectro-Microscope: Cs/Mo(110)

Energy Technology Data Exchange (ETDEWEB)

Grzelakowski, Krzysztof P., E-mail: k.grzelakowski@opticon-nanotechnology.com

2016-05-15

Since its introduction the importance of complementary k{sub ||}-space (LEED) and real space (LEEM) information in the investigation of surface science phenomena has been widely demonstrated over the last five decades. In this paper we report the application of a novel kind of electron spectromicroscope Dual Emission Electron spectroMicroscope (DEEM) with two independent electron optical channels for reciprocal and real space quasi-simultaneous imaging in investigation of a Cs covered Mo(110) single crystal by using the 800 eV electron beam from an “in-lens” electron gun system developed for the sample illumination. With the DEEM spectromicroscope it is possible to observe dynamic, irreversible processes at surfaces in the energy-filtered real space and in the corresponding energy-filtered k{sub ǁ}-space quasi-simultaneously in two independent imaging columns. The novel concept of the high energy electron beam sample illumination in the cathode lens based microscopes allows chemically selective imaging and analysis under laboratory conditions. - Highlights: • A novel concept of the electron sample illumination with “in-lens” e- gun is realized. • Quasi-simultaneous energy selective observation of the real- and k-space in EELS mode. • Observation of the energy filtered Auger electron diffraction at Cs atoms on Mo(110). • Energy-loss, Auger and secondary electron momentum microscopy is realized.

Statistical calculation of complete events in medium-energy nuclear collisions

International Nuclear Information System (INIS)

Randrup, J.

1984-01-01

Several heavy-ion accelerators throughout the world are presently able to deliver beams of heavy nuclei with kinetic energies in the range from tens to hundreds of MeV per nucleon, the so-called medium or intermediate energy range. At such energies a large number of final channels are open, each consisting of many nuclear fragments. The disassembly of the collision system is expected to be a very complicated process and a detailed dynamical description is beyond their present capability. However, by virtue of the complexity of the process, statistical considerations may be useful. A statistical description of the disassembly yields the least biased expectations about the outcome of a collision process and provides a meaningful reference against which more specific dynamical models, as well as the data, can be discussed. This lecture presents the essential tools for formulating a statistical model for the nuclear disassembly process. The authors consider the quick disassembly (explosion) of a hot nuclear system, a so-called source, into multifragment final states, which complete according to their statistical weight. First some useful notation is introduced. Then the expressions for exclusive and inclusive distributions are given and the factorization of an exclusive distribution into inclusive ones is carried out. In turn, the grand canonical approximation for one-fragment inclusive distributions is introduced. Finally, it is outlined how to generate a statistical sample of complete final states. On this basis, a model for statistical simulation of complete events in medium-energy nuclear collisions has been developed

Electron energy-loss spectra in molecular fluorine

Science.gov (United States)

Nishimura, H.; Cartwright, D. C.; Trajmar, S.

1979-01-01

Electron energy-loss spectra in molecular fluorine, for energy losses from 0 to 17.0 eV, have been taken at incident electron energies of 30, 50, and 90 eV and scattering angles from 5 to 140 deg. Features in the spectra above 11.5 eV energy loss agree well with the assignments recently made from optical spectroscopy. Excitations of many of the eleven repulsive valence excited electronic states are observed and their location correlates reasonably well with recent theoretical results. Several of these excitations have been observed for the first time and four features, for which there are no identifications, appear in the spectra.

Kinetic and electron-electron energies for convex sums of ground state densities with degeneracies and fractional electron number

Energy Technology Data Exchange (ETDEWEB)

Levy, Mel, E-mail: ayers@mcmaster.ca, E-mail: mlevy@tulane.edu [Department of Chemistry, Duke University, Durham, North Carolina 27708 (United States); Department of Physics, North Carolina A and T State University, Greensboro, North Carolina 27411 (United States); Department of Chemistry, Tulane University, New Orleans, Louisiana 70118 (United States); Anderson, James S. M.; Zadeh, Farnaz Heidar; Ayers, Paul W., E-mail: ayers@mcmaster.ca, E-mail: mlevy@tulane.edu [Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario (Canada)

2014-05-14

Properties of exact density functionals provide useful constraints for the development of new approximate functionals. This paper focuses on convex sums of ground-level densities. It is observed that the electronic kinetic energy of a convex sum of degenerate ground-level densities is equal to the convex sum of the kinetic energies of the individual degenerate densities. (The same type of relationship holds also for the electron-electron repulsion energy.) This extends a known property of the Levy-Valone Ensemble Constrained-Search and the Lieb Legendre-Transform refomulations of the Hohenberg-Kohn functional to the individual components of the functional. Moreover, we observe that the kinetic and electron-repulsion results also apply to densities with fractional electron number (even if there are no degeneracies), and we close with an analogous point-wise property involving the external potential. Examples where different degenerate states have different kinetic energy and electron-nuclear attraction energy are given; consequently, individual components of the ground state electronic energy can change abruptly when the molecular geometry changes. These discontinuities are predicted to be ubiquitous at conical intersections, complicating the development of universally applicable density-functional approximations.

Tests of an electron monitor for routine quality control measurements of electron energies

International Nuclear Information System (INIS)

Ramsay, E.B.; Reinstein, L.E.; Meek, A.G.

1991-01-01

The depth dose for electrons is sensitive to energy and the AAPM Task Group 24 has recommended that tests be performed at monthly intervals to assure electron beam energy constancy by verifying the depth for the 80% dose to within ±3 mm. Typically, this is accomplished by using a two-depth dose ratio technique. Recently, a new device, the Geske monitor, has been introduced that is designed for verifying energy constancy in a single reading. The monitor consists of nine parallel plate detectors that alternate with 5-mm-thick absorbers made of an aluminum alloy. An evaluation of the clinical usefulness of this monitor for the electron beams available on a Varian Clinac 20 has been undertaken with respect to energy discrimination. Beam energy changes of 3 mm of the 80% dose give rise to measurable output changes ranging from 1.7% for 20-MeV electron beams to 15% for 6-MeV electron beams

Secondary electron emission studied by secondary electron energy loss coincidence spectroscopy (SE2ELCS)

International Nuclear Information System (INIS)

Khalid, R.

2013-01-01

Emission of secondary electrons is of importance in many branches of fundamental and applied science. It is widely applied in the electron microscope for the investigation of the structure and electronic state of solid surfaces and particle detection in electron multiplier devices, and generally it is related to the energy dissipation of energetic particles moving inside a solid. The process of secondary electron emission is a complex physical phenomenon, difficult to measure experimentally and treat theoretically with satisfactory accuracy. The secondary electron spectrum measured with single electron spectroscopy does not provide detailed information of the energy loss processes responsible for the emission of secondary electrons. This information can be accessed when two correlated electron pairs are measured in coincidence and the pair consists of a backscattered electron after a given energy loss and a resulting emitted secondary electron. To investigate the mechanisms responsible for the emission of secondary electrons, a reflection (e,2e) coincidence spectrometer named Secondary Electron Electron Energy Loss Coincidence Spectrometer (SE2ELCS) has been developed in the framework of this thesis which allows one to uncover the relation between the features in the spectra which are due to energy losses and true secondary electron emission structures. The correlated electron pairs are measured with a hemispherical mirror analyzer (HMA) and a time of flight analyzer (TOF) by employing a continuous electron beam. An effort has been made to increase the coincidence count rate by increasing the effective solid angle of the TOF analyzer and optimizing the experimental parameters to get optimum energy resolution. Double differential coincidence spectra for a number of materials namely, nearly free electron metals (Al, Si), noble metals (Ag, Au, Cu, W) and highly oriented pyrolytic graphite (HOPG) have been measured using this coincidence spectrometer. The

Vibrational and electronic excitation of hexatriacontane thin films by low energy electron impact

International Nuclear Information System (INIS)

Vilar, M.R.; Schott, M.; Pfluger, P.

1990-01-01

Thin polycrystalline films of hexatriacontane (HTC) were irradiated with low energy (E=0.5--15 eV) electrons, and off-specular backscattered electron spectra were measured. Below E∼7 eV, single and multiple vibrational excitations only are observed, which relax the electrons down to the bottom of the HTC conduction band. Due to the negative electron affinity of HTC, thermal electrons are emitted into vacuum. Structure in the backscattered electron current at kinetic energies about 1.5 and 4 eV are associated to conduction band density of states. Above E∼7 eV, the dominant losses correspond to electronic excitations, excitons, or above a threshold (energy of the electron inside the HTC film) at 9.2±0.1 eV, electron--hole pair generation. The latter process is very efficient and reaches a yield of the order of one ∼11 eV. Evidence for chemical reaction above E∼4 eV is observed

Surface sterilization by low energy electron beams

International Nuclear Information System (INIS)

Sekiguchi, Masayuki; Tabei, Masae

1989-01-01

The germicidal effectiveness of low energy electron beams (175 KV) against bacterial cells was investigated. The dry spores of Bacillus pumilus ATCC 27142 and Bacillus globigii ATCC 9372 inoculated on carrier materials and irradiated by gamma rays showed the exponential type of survival curves whereas they showed sigmoidal ones when exposed to low energy electron beams. When similarly irradiated, the wet spores inoculated on membrane filter showed the same survival curves as the dry spores inoculated on carrier materials. The wet vegetative cells of Escherichia coli ATCC 25922 showed exponential curves when exposed to gamma and electron beam irradiation. Low energy electron beams in air showed little differences from nitrogen stream in their germicidal effectiveness against dry spores of B. pumilus. The D values of B. pumilus spores inoculated on metal plates decreased as the amounts of backscattering electrons from the plates increased. There was adequate correlation between the D value (linear region of survival curve), average D value (6D/6) and 1% survival dose and backscattering factor. Depth dose profile and backscatterig dose of low energy electron beams were measured by radiochromic dye film dosimeter (RCD). These figures were not always in accord with the observed germicidal effectiveness against B. pumilus spores because of varying thickness of RCD and spores inoculated on carrier material. The dry spores were very thin and this thinness was useful in evaluating the behavior of low energy electrons. (author)

Electron correlation energy in confined two-electron systems

Energy Technology Data Exchange (ETDEWEB)

Wilson, C.L. [Chemistry Program, Centre College, 600 West Walnut Street, Danville, KY 40422 (United States); Montgomery, H.E., E-mail: ed.montgomery@centre.ed [Chemistry Program, Centre College, 600 West Walnut Street, Danville, KY 40422 (United States); Sen, K.D. [School of Chemistry, University of Hyderabad, Hyderabad 500 046 (India); Thompson, D.C. [Chemistry Systems and High Performance Computing, Boehringer Ingelheim Pharamaceuticals Inc., 900 Ridgebury Road, Ridgefield, CT 06877 (United States)

2010-09-27

Radial, angular and total correlation energies are calculated for four two-electron systems with atomic numbers Z=0-3 confined within an impenetrable sphere of radius R. We report accurate results for the non-relativistic, restricted Hartree-Fock and radial limit energies over a range of confinement radii from 0.05-10a{sub 0}. At small R, the correlation energies approach limiting values that are independent of Z while at intermediate R, systems with Z{>=}1 exhibit a characteristic maximum in the correlation energy resulting from an increase in the angular correlation energy which is offset by a decrease in the radial correlation energy.

Computer simulation program for medium-energy ion scattering and Rutherford backscattering spectrometry

Energy Technology Data Exchange (ETDEWEB)

Nishimura, Tomoaki, E-mail: t-nishi@hosei.ac.jp

2016-03-15

A computer simulation program for ion scattering and its graphical user interface (MEISwin) has been developed. Using this program, researchers have analyzed medium-energy ion scattering and Rutherford backscattering spectrometry at Ritsumeikan University since 1998, and at Rutgers University since 2007. The main features of the program are as follows: (1) stopping power can be chosen from five datasets spanning several decades (from 1977 to 2011), (2) straggling can be chosen from two datasets, (3) spectral shape can be selected as Gaussian or exponentially modified Gaussian, (4) scattering cross sections can be selected as Coulomb or screened, (5) simulations adopt the resonant elastic scattering cross section of {sup 16}O({sup 4}He, {sup 4}He){sup 16}O, (6) pileup simulation for RBS spectra is supported, (7) natural and specific isotope abundances are supported, and (8) the charge fraction can be chosen from three patterns (fixed, energy-dependent, and ion fraction with charge-exchange parameters for medium-energy ion scattering). This study demonstrates and discusses the simulations and their results.

Potential application of electron accelerators in Malaysia

Energy Technology Data Exchange (ETDEWEB)

Alang Md Rashid, Nahrul Khair; Mohd Dahlan, Khairul Zaman [Nuclear Energy Unit, Bangi, Selangor (Malaysia)

1994-12-31

Briefly discussed some applications of electron accelerators i.e. sterilization, pasteurization (high energy EBM - up to 10 MV), crosslinking of wire and cable and insulation (medium energy EBM - 1 to 5 MV), treatment of flue gases for removal of NO sub x and SO sub x from burning coal(low energy EBM - 700 to 900 kV), curing of surface coatings, printing ink, adhesives (low energy EBM - 200 to 500 kV); advantages and electron beam processing.

Potential application of electron accelerators in Malaysia

International Nuclear Information System (INIS)

Nahrul Khair Alang Md Rashid; Khairul Zaman Mohd Dahlan

1994-01-01

Briefly discussed some applications of electron accelerators i.e. sterilization, pasteurization (high energy EBM - up to 10 MV), crosslinking of wire and cable and insulation (medium energy EBM - 1 to 5 MV), treatment of flue gases for removal of NO sub x and SO sub x from burning coal(low energy EBM - 700 to 900 kV), curing of surface coatings, printing ink, adhesives (low energy EBM - 200 to 500 kV); advantages and electron beam processing

Medium energy nuclear physics research

International Nuclear Information System (INIS)

Peterson, G.A.; Dubach, J.F.; Hicks, R.S.; Miskimen, R.A.

1992-06-01

This paper covers the following topics: Experiment 87-02: Threshold Electrodisintegration of the Deuteron at High Q 2 ; Measurement of the 5th Structure Function in Deuterium and 12 C; Single-Particle Densities of sd-Shell Nuclei; Experiment 84-28: Transverse Form Factors of 117 Sn; Experiment 82-11: Elastic Magnetic Electron Scattering from 13 C; Experiment 89-09: Measurement of the Elastic Magnetic Form Factor of 3 He at High Momentum Transfer; Experiment 89-15: Coincidence Measurement of the D(e,e'p) Cross-Section at Low Excitation Energy and High Momentum Transfer; Experiment 87-09: Measurement of the Quadrupole Contribution to the N → Δ Excitation; Experiment E-140: Measurement of the x-, Q 2 and A-Dependence of R = σ L /σ T ; PEP Beam-Gas Event Analysis: Physics with the SLAC TPC/2γ Detector; Drift Chamber Tests at Brookhaven National Laboratory; Experiment PR-89-031: Multi-nucleon Knockout Using the CLAS Detector; Electronics Design for the CLAS Region 1 Drift Chamber; Color Transparencies in the Electroproduction of Nucleon Resonances; and Experiment PR-89-015: Study of Coincidence Reactions in the Dip and Delta-Resonance Regions

Medium energy measurements of n-n parameters: Progress in research, January 1, 1986-December 31, 1986

International Nuclear Information System (INIS)

Riley, P.J.

1987-01-01

A major part of the work has been and will continue to be associated with research done at the Nucleon Physics Laboratory (NPL) at the Los Alamos Meson Physics Facility (LAMPF). The aim of the experimental program is the determination of the nucleon-nucleon amplitudes at medium energy. The required data include both elastic and inelastic experiments, and in addition the measurement of polarization and polarization transfer parameters. We have been emphasizing single pion production measurements using polarized proton beams, and expect that our present data base will provide stringent tests of theoretical models. With the development of the LAMPF high intensity polarized proton source, we expect that a reasonably intense beam of medium energy polarized neutrons will become available, and are planning a series of experiments utilizing polarized neutrons to determine the importance of the I = 0 reaction amplitudes at medium energies

Food irradiation by low energy electrons

International Nuclear Information System (INIS)

Bird, J.R.

1985-01-01

For some special cases, the use of low energy electrons has advantages over the use of gamma-rays or higher energy electrons for the direct irradiation of food. These advantages arise from details of the interaction processes which are responsible for the production of physical, chemical and biological effects. Factors involved include depth of penetration, dose distribution, irradiation geometry, the possible production of radioactivity and costs

A simultaneous electron energy and dosimeter calibration method for an electron beam irradiator

International Nuclear Information System (INIS)

Tanaka, R.; Sunaga, H.; Kojima, T.

1991-01-01

In radiation processing using electron accelerators, the reproducibility of absorbed dose in the product depends not only on the variation of beam current and conveyor speed, but also on variations of other accelerator parameters. This requires routine monitoring of the beam current and the scan width, and also requires periodical calibration of routine dosimeters usually in the shape of film, electron energy, and other radiation field parameters. The electron energy calibration is important especially for food processing. The dose calibration method using partial absorption calorimeters provides only information about absorbed dose. Measurement of average electron current density provides basic information about the radiation field formed by the beam scanning and scattering at the beam window, though it does not allow direct dose calibration. The total absorption calorimeter with a thick absorber allows dose and dosimeter calibration, if the depth profile of relative dose in a reference absorber is given experimentally. It also allows accurate calibration of the average electron energy at the surface of the calorimeter core, if electron fluence received by the calorimeter is measured at the same time. This means that both electron energy and dosimeters can be simultaneously calibrated by irradiation of a combined system including the calorimeter, the detector of the electron current density meter, and a thick reference absorber for depth profile measurement of relative dose. We have developed a simple and multifunctional system using the combined calibration method for 5 MeV electron beams. The paper describes a simultaneous calibration method for electron energy and film dosimeters, and describes the electron current density meter, the total absorption calorimeter, and the characteristics of this method. (author). 13 refs, 7 figs, 3 tabs

Generation of Low-Energy High-Current Electron Beams in Plasma-Anode Electron Guns

Science.gov (United States)

Ozur, G. E.; Proskurovsky, D. I.

2018-01-01

This paper is a review of studies on the generation of low-energy high-current electron beams in electron guns with a plasma anode and an explosive-emission cathode. The problems related to the initiation of explosive electron emission under plasma and the formation and transport of high-current electron beams in plasma-filled systems are discussed consecutively. Considerable attention is given to the nonstationary effects that occur in the space charge layers of plasma. Emphasis is also placed on the problem of providing a uniform energy density distribution over the beam cross section, which is of critical importance in using electron beams of this type for surface treatment of materials. Examples of facilities based on low-energy high-current electron beam sources are presented and their applications in materials science and practice are discussed.

Low energy intense electron beams with extra-low energy spread

International Nuclear Information System (INIS)

Aleksandrov, A.V.; Calabrese, R.; Ciullo, G.; Dikansky, N.S.; Guidi, V.; Kot, N.C.; Kudelainen, V.I.; Lamanna, G.; Lebedev, V.A.; Logachov, P.V.; Tecchio, L.; Yang, B.

1994-01-01

Maximum achievable intensity for low energy electron beams is a feature that is not very often compatible with low energy spread. We show that a proper choice of the source and the acceleration optics allows one to match them together. In this scheme, a GaAs photocathode excited by a single-mode infrared laser and adiabatic acceleration in fully magnetised optics enables the production of a low-energy-spread electron beam with relatively high intensity. The technological problems associated with the method are discussed together with its limitations. (orig.)

A program in medium-energy nuclear physics

International Nuclear Information System (INIS)

Berman, B.L.; Dhuga, K.S.

1992-01-01

This report reviews progress on our nuclear-physics program for the last year, and includes as well copies of our publications and other reports for that time period. The structure of this report follows that of our 1991 Renewal Proposal and Progress Report: Sec. II outlines our research activities aimed at future experiments at CEBAF, NIKHEF, and Bates; Sec. III gives results of our recent research activities at NIKHEF, LAMPF, and elsewhere; Sec. IV provides an update of our laboratory activities at GWU, including the acquisition of our new Nuclear Detector Laboratory at our new Virginia Campus; and Sec. V is a list of our publications, proposals, and other reports. copies of those on medium-energy nuclear physics are reproduced in the Appendix

Performance of the electron energy-loss spectrometer

International Nuclear Information System (INIS)

Tanaka, H.; Huebner, R.H.

1977-01-01

Performance characteristics of the electron energy-loss spectrometer incorporating a new high-resolution hemispherical monochromator are reported. The apparatus achieved an energy-resolution of 25 meV in the elastic scattering mode, and angular distributions of elastically scattered electrons were in excellent agreement with previous workers. Preliminary energy-loss spectra for several atmospheric gases demonstrate the excellent versatility and stable operation of the improved system. 12 references

Properties of the electron cloud in a high-energy positron and electron storage ring

International Nuclear Information System (INIS)

Harkay, K.C.; Rosenberg, R.A.

2003-01-01

Low-energy, background electrons are ubiquitous in high-energy particle accelerators. Under certain conditions, interactions between this electron cloud and the high-energy beam can give rise to numerous effects that can seriously degrade the accelerator performance. These effects range from vacuum degradation to collective beam instabilities and emittance blowup. Although electron-cloud effects were first observed two decades ago in a few proton storage rings, they have in recent years been widely observed and intensely studied in positron and proton rings. Electron-cloud diagnostics developed at the Advanced Photon Source enabled for the first time detailed, direct characterization of the electron-cloud properties in a positron and electron storage ring. From in situ measurements of the electron flux and energy distribution at the vacuum chamber wall, electron-cloud production mechanisms and details of the beam-cloud interaction can be inferred. A significant longitudinal variation of the electron cloud is also observed, due primarily to geometrical details of the vacuum chamber. Such experimental data can be used to provide realistic limits on key input parameters in modeling efforts, leading ultimately to greater confidence in predicting electron-cloud effects in future accelerators.

Electron energy and electron trajectories in an inverse free-electron laser accelerator based on a novel electrostatic wiggler

Science.gov (United States)

Nikrah, M.; Jafari, S.

2016-06-01

We expand here a theory of a high-gradient laser-excited electron accelerator based on an inverse free-electron laser (inverse-FEL), but with innovations in the structure and design. The electrostatic wiggler used in our scheme, namely termed the Paul wiggler, is generated by segmented cylindrical electrodes with applied oscillatory voltages {{V}\\text{osc}}(t) over {{90}\\circ} segments. The inverse-FEL interaction can be described by the equations that govern the electron motion in the combined fields of both the laser pulse and Paul wiggler field. A numerical study of electron energy and electron trajectories has been made using the fourth-order Runge-Kutta method. The results indicate that the electron attains a considerable energy at short distances in this device. It is found that if the electron has got sufficient suitable wiggler amplitude intensities, it can not only gain higher energy in longer distances, but also can retain it even after the passing of the laser pulse. In addition, the results reveal that the electron energy gains different peaks for different initial axial velocities, so that a suitable small initial axial velocity of e-beam produces substantially high energy gain. With regard to the transverse confinement of the electron beam in a Paul wiggler, there is no applied axial guide magnetic field in this device.

An energy recovery electron linac-on-ring collider

International Nuclear Information System (INIS)

Merminga, L.; Krafft, G.A.; Lebedev, V.A.; Ben-Zvi, I.

2000-01-01

We present the design of high-luminosity electron-proton/ion colliders in which the electrons are produced by an Energy Recovering Linac (ERL). Electron-proton/ion colliders with center of mass energies between 14 GeV and 100 GeV (protons) or 63 GeV/A (ions) and luminosities at the 10 33 (per nucleon) level have been proposed recently as a means for studying hadronic structure. The linac-on-ring option presents significant advantages with respect to: (1) spin manipulations (2) reduction of the synchrotron radiation load in the detectors (3) a wide range of continuous energy variability. Rf power and beam dump considerations require that the electron linac recover the beam energy. Based on extrapolations from actual measurements and calculations, energy recovery is expected to be feasible at currents of a few hundred mA and multi-GeV energies. Luminosity projections for the linac-ring scenario based on fundamental limitations are presented. The feasibility of an energy recovery electron linac-on-proton ring collider is investigated and four conceptual point designs are shown corresponding to electron to proton energies of: 3 GeV on 15 GeV, 5 GeV on 50 GeV and 10 GeV on 250 GeV, and for gold ions with 100 GeV/A. The last two designs assume that the protons or ions are stored in the existing RHIC accelerator. Accelerator physics issues relevant to proton rings and energy recovery linacs are discussed and a list of required R and D for the realization of such a design is presented

Some topics concerning N--N and N--D experiments at medium energy

International Nuclear Information System (INIS)

Simmons, J.E.

1975-01-01

The status of recent proton-proton phase shift analyses is reviewed at medium energy with mention of the state of the n-p I = 0 analyses. Some conclusions are reached, including a recommendation for renewed theoretical effort to calculate absorption parameters for N--N scattering above 300 MeV in higher partial waves (l greater than or equal to 3). Recent experimental data are examined for p-p small angle scattering at 630 MeV and also near 500 MeV. Further small angle experiments on p-p and p-d scattering are deemed desirable. A brief discussion of recent n-p charge exchange experiments is given. Finally, the status of medium to high energy (100 to 2000 MeV) p-d elastic scattering is reviewed with emphasis on back angle scattering and the usefulness of p-d polarization measurements. (1 table, 12 figures, 94 references) (U.S.)

Temperature-dependent surface structure, composition, and electronic properties of the clean SrTiO3(111) crystal face: Low-energy-electron diffraction, Auger-electron spectroscopy, electron energy loss, and ultraviolet-photoelectron spectroscopy studies

International Nuclear Information System (INIS)

Lo, W.J.; Somorjai, G.A.

1978-01-01

Low-energy-electron diffraction, Auger-electron spectroscopy, electron-energy-loss, and ultraviolet-photoelectron spectroscopies were used to study the structure, composition, and electron energy distribution of a clean single-crystal (111) face of strontium titanate (perovskite). The dependence of the surface chemical composition on the temperature has been observed along with corresponding changes in the surface electronic properties. High-temperature Ar-ion bombardment causes an irreversible change in the surface structure, stoichiometry, and electron energy distribution. In contrast to the TiO 2 surface, there are always significant concentrations of Ti 3+ in an annealed ordered SrTiO 3 (111) surface. This stable active Ti 3+ monolayer on top of a substrate with large surface dipole potential makes SrTiO 3 superior to TiO 2 when used as a photoanode in the photoelectrochemical cell

Medium-energy physics program. Progress report, August 1--October 31, 1977

Energy Technology Data Exchange (ETDEWEB)

van Dyck, O.B.; Dunn, E.D. (comps.)

1978-05-01

A report is given of the medium-energy physics program at the LAMPF linac for the period from August 1 through October 31, 1977. Topics discussed include: (1) accelerator facilities and development; (2) the main beam lines; (3) experimental areas; (4) research; (5) nuclear chemistry; (6) practical applications; (7) linac technology; and (8) management. (PMA)

Medium-energy physics program. Progress report, August 1--October 31, 1977

International Nuclear Information System (INIS)

van Dyck, O.B.; Dunn, E.D.

1978-05-01

A report is given of the medium-energy physics program at the LAMPF linac for the period from August 1 through October 31, 1977. Topics discussed include: (1) accelerator facilities and development; (2) the main beam lines; (3) experimental areas; (4) research; (5) nuclear chemistry; (6) practical applications; (7) linac technology; and (8) management

Energy Conversion Mechanism for Electron Perpendicular Energy in High Guide-Field Reconnection

Science.gov (United States)

Guo, Xuehan; Horiuchi, Ritoku; Kaminou, Yasuhiro; Cheng, Frank; Ono, Yasushi

2016-10-01

The energy conversion mechanism for electron perpendicular energy, both the thermal and the kinetic energy, is investigated by means of two-dimensional, full-particle simulations in an open system. It is shown that electron perpendicular heating is mainly due to the breaking of magnetic moment conservation in separatrix region because the charge separation generates intense variation of electric field within the electron Larmor radius. Meanwhile, electron perpendicular acceleration takes place manly due to the polarization drift term as well as the curvature drift term of E . u⊥ in the downstream near the X-point. The enhanced electric field due to the charge separation there results in a significant effect of the polarization drift term on the dissipation of magnetic energy within the ion inertia length in the downstream. Japan Society for the Promotion of Science (JSPS) Fellows 15J03758.

Analytic energy gradient of excited electronic state within TDDFT/MMpol framework: Benchmark tests and parallel implementation.

Science.gov (United States)

Zeng, Qiao; Liang, WanZhen

2015-10-07

The time-dependent density functional theory (TDDFT) has become the most popular method to calculate the electronic excitation energies, describe the excited-state properties, and perform the excited-state geometric optimization of medium and large-size molecules due to the implementation of analytic excited-state energy gradient and Hessian in many electronic structure software packages. To describe the molecules in condensed phase, one usually adopts the computationally efficient hybrid Quantum Mechanics/Molecular Mechanics (QM/MM) models. Here, we extend our previous work on the energy gradient of TDDFT/MM excited state to account for the mutual polarization effects between QM and MM regions, which is believed to hold a crucial position in the potential energy surface of molecular systems when the photoexcitation-induced charge rearrangement in the QM region is drastic. The implementation of a simple polarizable TDDFT/MM (TDDFT/MMpol) model in Q-Chem/CHARMM interface with both the linear response and the state-specific features has been realized. Several benchmark tests and preliminary applications are exhibited to confirm our implementation and assess the effects of different treatment of environmental polarization on the excited-state properties, and the efficiency of parallel implementation is demonstrated as well.

Charge-coupled device area detector for low energy electrons

International Nuclear Information System (INIS)

Horacek, Miroslav

2003-01-01

A fast position-sensitive detector was designed for the angle- and energy-selective detection of signal electrons in the scanning low energy electron microscope (SLEEM), based on a thinned back-side directly electron-bombarded charged-coupled device (CCD) sensor (EBCCD). The principle of the SLEEM operation and the motivation for the development of the detector are explained. The electronics of the detector is described as well as the methods used for the measurement of the electron-bombarded gain and of the dark signal. The EBCCD gain of 565 for electron energy 5 keV and dynamic range 59 dB for short integration time up to 10 ms at room temperature were obtained. The energy dependence of EBCCD gain and the detection efficiency are presented for electron energy between 2 and 5 keV, and the integration time dependence of the output signals under dark conditions is given for integration time from 1 to 500 ms

Electron emission from materials at low excitation energies

International Nuclear Information System (INIS)

Urma, N.; Kijek, M.; Millar, J.J.

1996-01-01

Full text: An experimental system has been designed and developed with the purpose of measuring the total electron emission yield from materials at low energy excitation. In the first instance the reliability of the system was checked by measuring the total electron emission yield for a well defined surface (aluminium 99.45%). The obtained data was in the expected range given by the literature, and consequently the system will be used further for measuring the total electron yield for a range of materials with interest in the instrumentation industry. We intend to measure the total electron emission yield under electron bombardment as a function of incident electron energy up to 1200 eV, angle of incidence, state of the surface and environment to which the surface has been exposed. Dependence of emission on total electron irradiated dose is also of interest. For many practical application of the 'Secondary Electron Emission', the total electron yield is desired to be as large as possible. The above phenomenon has practical applicability in electron multiplier tube and Scanning electron microscopy - when by means of the variation of the yield of the emitted electrons one may produce visible images of small sample areas. The electron multiplier tube, is a device which utilises the above effect to detect and amplify both single particles and low currents streams of charged particles. The majority of electron tubes use electrons with low energy, hundreds of eV. Not a lot has been published in the literature about this regime and also about the emission when the impinging electrons have small energy, up to 1 KeV. The information obtained from the experimental measurements concerning the total electron emission yield is used to asses the investigated materials as a potential electron emitting surfaces or dynodes in an electron multiplier tube

Measurements of Coulomb Cross Section for Production of Direct Electron-pairs by High Energy Ions at the CERN SPS

CERN Multimedia

2002-01-01

QED predicts copious direct electron pair production by ultrarelativistic heavy nuclei in a high Z medium such as nuclear emulsion. First order QED calculations (combined screening and non-screening) for this process show that 1000@+32 electron pairs above 100~keV energy) should be emitted for a total |1|6O track length of 10.9~m in nuclear emulsion at 200~GeV/AMU. Emulsion exposures with oxygen (and other nuclei if available) at 60 and 200~GeV/AMU will be used to calibrate the energy dependent cross section @s~@j~(1n~E)|2|-|3, whose exponent depends on atomic screening. The oxygen tracks in the developed emulsions will be scanned with a microscope, and the number of direct electron pairs will be counted for individual tracks. The exposed stacks will contain sufficient emulsion (and CR39 plastic to check for possible interactions) that adequate path length will be available for exposures to @$>$~10|4~ions at each energy and ion species. \\\\ \\\\ If the absolute value of this cross section is confirmed as large a...

An Application of the Direct Coulomb Electron Pair Production Process to the Energy Measurement of the "VH-Group" in the "Knee" Region of the "All-Particle" Energy Spectrum

Science.gov (United States)

Derrickson, J. H.; Wu, J.; Christl, M. J.; Fountain, W. F.; Parnell, T. A.

1999-01-01

The "all-particle" cosmic ray energy spectrum appears to be exhibiting a significant change in the spectral index just above approximately 3000 TeV. This could indicate (1) a change in the propagation of the cosmic rays in the galactic medium, and/or (2) the upper limit of the supernova shock wave acceleration mechanism, and/or (3) a new source of high-energy cosmic rays. Air shower and JACEE data indicate the spectral change is associated with a composition change to a heavier element mixture whereas DICE does not indicate this. A detector concept will be presented that utilizes the energy dependence of the production of direct Coulomb electron-positron pairs by energetic heavy ions. Monte Carlo simulations of a direct electron pair detector consisting of Pb target foils interleaved with planes of 1-mm square scintillating optical fibers will be discussed. The goal is to design a large area, non-saturating instrument to measure the energy spectrum of the individual cosmic ray elements in the "VH-group" for energies greater than 10 TeV/nucleon.

Electron energy distribution function, effective electron temperature, and dust charge in the temporal afterglow of a plasma

International Nuclear Information System (INIS)

Denysenko, I. B.; Azarenkov, N. A.; Kersten, H.

2016-01-01

Analytical expressions describing the variation of electron energy distribution function (EEDF) in an afterglow of a plasma are obtained. Especially, the case when the electron energy loss is mainly due to momentum-transfer electron-neutral collisions is considered. The study is carried out for different EEDFs in the steady state, including Maxwellian and Druyvesteyn distributions. The analytical results are not only obtained for the case when the rate for momentum-transfer electron-neutral collisions is independent on electron energy but also for the case when the collisions are a power function of electron energy. Using analytical expressions for the EEDF, the effective electron temperature and charge of the dust particles, which are assumed to be present in plasma, are calculated for different afterglow durations. An analytical expression for the rate describing collection of electrons by dust particles for the case when the rate for momentum-transfer electron-neutral collisions is independent on electron energy is also derived. The EEDF profile and, as a result, the effective electron temperature and dust charge are sufficiently different in the cases when the rate for momentum-transfer electron-neutral collisions is independent on electron energy and when the rate is a power function of electron energy.

An energy monitor for electron accelerators

International Nuclear Information System (INIS)

Geske, G.

1990-01-01

A monitor useful for checks of the energy selector scale of medical electron accelerators was developed and tested. It consists of a linear array of flat ionization chambers sandwiched between absorber plates of low-Z material. The first chamber at the electron beam entrance may be used to produce a reference signal S r , if not another suitable reference signal is taken. The following chambers are electrically connected and deliver the measuring signal S m . A clinical dosimeter can be used for recording current or charge. The energy-dependent electron range parameters R p , R 50 and R 80 in water vary as linear functions of the ratio reference singal/measuring signal. The best linear fit was obtained for the half value layer R 50 . Three types of the energy monitor are described, and experimental results obtained with a linear accelerator and a betatron between 5 and 25 MeV are reported. Uncertainties for checks of R 50 with a calibrated energy monitor were not larger than 1 to 2 mm. Theoretical considerations by a computer model support these results. (orig./HP) [de

Dependence of Energetic Electron Precipitation on the Geomagnetic Index Kp and Electron Energy

Directory of Open Access Journals (Sweden)

Mi-Young Park

2013-12-01

Full Text Available It has long been known that the magnetospheric particles can precipitate into the atmosphere of the Earth. In this paper we examine such precipitation of energetic electrons using the data obtained from low-altitude polar orbiting satellite observations. We analyze the precipitating electron flux data for many periods selected from a total of 84 storm events identified for 2001-2012. The analysis includes the dependence of precipitation on the Kp index and the electron energy, for which we use three energies E1 > 30 keV, E2 > 100 keV, E3 > 300 keV. We find that the precipitation is best correlated with Kp after a time delay of < 3 hours. Most importantly, the correlation with Kp is notably tighter for lower energy than for higher energy in the sense that the lower energy precipitation flux increases more rapidly with Kp than does the higher energy precipitation flux. Based on this we suggest that the Kp index reflects excitation of a wave that is responsible for scattering of preferably lower energy electrons. The role of waves of other types should become increasingly important for higher energy, for which we suggest to rely on other indicators than Kp if one can identify such an indicator.

Power electronic solutions for interfacing offshore wind turbine generators to medium voltage DC collection grids

Science.gov (United States)

Daniel, Michael T.

Here in the early 21st century humanity is continuing to seek improved quality of life for citizens throughout the world. This global advancement is providing more people than ever with access to state-of-the-art services in areas such as transportation, entertainment, computing, communication, and so on. Providing these services to an ever-growing population while considering the constraints levied by continuing climate change will require new frontiers of clean energy to be developed. At the time of this writing, offshore wind has been proven as both a politically and economically agreeable source of clean, sustainable energy by northern European nations with many wind farms deployed in the North, Baltic, and Irish Seas. Modern offshore wind farms are equipped with an electrical system within the farm itself to aggregate the energy from all turbines in the farm before it is transmitted to shore. This collection grid is traditionally a 3-phase medium voltage alternating current (MVAC) system. Due to reactive power and other practical constraints, it is preferable to use a medium voltage direct current (MVDC) collection grid when siting farms >150 km from shore. To date, no offshore wind farm features an MVDC collection grid. However, MVDC collection grids are expected to be deployed with future offshore wind farms as they are sited further out to sea. In this work it is assumed that many future offshore wind farms may utilize an MVDC collection grid to aggregate electrical energy generated by individual wind turbines. As such, this work presents both per-phase and per-pole power electronic converter systems suitable for interfacing individual wind turbines to such an MVDC collection grid. Both interfaces are shown to provide high input power factor at the wind turbine while providing DC output current to the MVDC grid. Common mode voltage stress and circulating currents are investigated, and mitigation strategies are provided for both interfaces. A power sharing

The interaction of low-energy electrons with fructose molecules

Science.gov (United States)

Chernyshova, I. V.; Kontrosh, E. E.; Markush, P. P.; Shpenik, O. B.

2017-11-01

Using a hypocycloidal electronic spectrometer, the interactions of low energy electrons (0-8.50 eV) with fructose molecules, namely, electron scattering and dissociative attachment, are studied. The results of these studies showed that the fragmentation of fructose molecules occurs effectively even at an electron energy close to zero. In the total electron-scattering cross section by molecules, resonance features (at energies 3.10 and 5.00 eV) were first observed near the formation thresholds of light ion fragments OH- and H-. The correlation of the features observed in the cross sections of electron scattering and dissociative attachment is analyzed.

SU-F-I-13: Correction Factor Computations for the NIST Ritz Free Air Chamber for Medium-Energy X Rays

International Nuclear Information System (INIS)

Bergstrom, P

2016-01-01

Purpose: The National Institute of Standards and Technology (NIST) uses 3 free-air chambers to establish primary standards for radiation dosimetry at x-ray energies. For medium-energy × rays, the Ritz free-air chamber is the main measurement device. In order to convert the charge or current collected by the chamber to the radiation quantities air kerma or air kerma rate, a number of correction factors specific to the chamber must be applied. Methods: We used the Monte Carlo codes EGSnrc and PENELOPE. Results: Among these correction factors are the diaphragm correction (which accounts for interactions of photons from the x-ray source in the beam-defining diaphragm of the chamber), the scatter correction (which accounts for the effects of photons scattered out of the primary beam), the electron-loss correction (which accounts for electrons that only partially expend their energy in the collection region), the fluorescence correction (which accounts for ionization due to reabsorption ffluorescence photons and the bremsstrahlung correction (which accounts for the reabsorption of bremsstrahlung photons). We have computed monoenergetic corrections for the NIST Ritz chamber for the 1 cm, 3 cm and 7 cm collection plates. Conclusion: We find good agreement with other’s results for the 7 cm plate. The data used to obtain these correction factors will be used to establish air kerma and it’s uncertainty in the standard NIST x-ray beams.

SU-F-I-13: Correction Factor Computations for the NIST Ritz Free Air Chamber for Medium-Energy X Rays

Energy Technology Data Exchange (ETDEWEB)

Bergstrom, P [National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899 (United States)

2016-06-15

Purpose: The National Institute of Standards and Technology (NIST) uses 3 free-air chambers to establish primary standards for radiation dosimetry at x-ray energies. For medium-energy × rays, the Ritz free-air chamber is the main measurement device. In order to convert the charge or current collected by the chamber to the radiation quantities air kerma or air kerma rate, a number of correction factors specific to the chamber must be applied. Methods: We used the Monte Carlo codes EGSnrc and PENELOPE. Results: Among these correction factors are the diaphragm correction (which accounts for interactions of photons from the x-ray source in the beam-defining diaphragm of the chamber), the scatter correction (which accounts for the effects of photons scattered out of the primary beam), the electron-loss correction (which accounts for electrons that only partially expend their energy in the collection region), the fluorescence correction (which accounts for ionization due to reabsorption ffluorescence photons and the bremsstrahlung correction (which accounts for the reabsorption of bremsstrahlung photons). We have computed monoenergetic corrections for the NIST Ritz chamber for the 1 cm, 3 cm and 7 cm collection plates. Conclusion: We find good agreement with other’s results for the 7 cm plate. The data used to obtain these correction factors will be used to establish air kerma and it’s uncertainty in the standard NIST x-ray beams.

Electron scattering from sodium at intermediate energies

International Nuclear Information System (INIS)

Mitroy, J.; McCarthy, I.E.

1986-10-01

A comprehensive comparison is made between theoretical calculations and experimental data for intermediate energy (≥ 10 eV) electron scattering from sodium vapour. The theoretical predictions of coupled-channels calculations (including one, two or four channels) do not agree with experimental values of the differential cross sections for elastic scattering or the resonant 3s to 3p excitation. Increasingly-more-sophisticated calculations, incorporating electron correlations in the target states, and also including core-excited states in the close-coupling expansion, are done at a few selected energies in an attempt to isolate the cause of the discrepancies between theory and experiment. It is found that these more-sophisticated calculations give essentially the same results as the two- and four-channel calculations using Hartree-Fock wavefunctions. Comparison of the sodium high-energy elastic differential cross sections with those of neon suggests that the sodium differential cross section experiments may suffer from systematic errors. There is also disagreement, at the higher energies, between theoretical values for the scattering parameters and those that are derived from laser-excited superelastic scattering and electron photon coincidence experiments. When allowance is made for the finite acceptance angle of the electron spectrometers used in the experiments by convoluting the theory with a function representing the distribution of electrons entering the electron spectrometer it is found that the magnitudes of the differences between theory and experiment are reduced

Acceleration of polarized electrons in the Bonn electron-accelerator facility ELSA

International Nuclear Information System (INIS)

Hoffmann, M.

2001-12-01

The future medium energy physics program at the electron stretcher accelerator ELSA of Bonn University mainly relies on experiments using polarized electrons in the energy range from 1 to 3.2 GeV. To prevent depolarization during acceleration in the circular accelerators several depolarizing resonances have to be corrected for. Intrinsic resonances are compensated using two pulsed betatron tune jump quadrupoles. The influence of imperfection resonances is successfully reduced applying a dynamic closed orbit correction in combination with an empirical harmonic correction on the energy ramp. Both types of resonances and the correction techniques have been studied in detail. The imperfection resonances were used to calibrate the energy of the stretcher ring with high accuracy. A new technique to extract the beam with horizontal oriented polarization was successfully installed. For all energies a polarized electron beam with more than 50% polarization can now be supplied to the experiments at ELSA, which is demonstrated by measurements using a Moeller polarimeter installed in the external beamline. (orig.)

Electronic market places in the energy

International Nuclear Information System (INIS)

Mons, L.

2001-12-01

Electronic market places in the energy domain occurred at the end of the 90's in the US and have started to develop in Europe in the year 2000. About 60 platforms are registered today and this development can be explained by the advantages raised by such an infrastructure: simplification of purchase procedures, reduction of delays in the purchase decision, reduction of administrative costs etc.. However, today none of these electronic market places is profitable and several have closed down. On the other hand, this tool will certainly become necessary in the future and all energy actors are developing projects in this way. This study analyzes the electronic market places phenomenon in the energy domain using 10 market places examples with their key-factors of success. It draws out a complete status of the initiatives developed today and presents some scenarios of evolution. (J.S.)

Fermi-Dirac function and energy gap

OpenAIRE

Bondarev, Boris

2013-01-01

Medium field method is applied for studying valence electron behavior in metals. When different wave-vector electrons are attracted at low temperatures, distribution function gets discontinued. As a result, a specific energy gap occurs.

Beam dosimetry in high-power electron accelerators

International Nuclear Information System (INIS)

Popov, V.N.; Zhitomirskii, B.M.; Ermakov, A.N.; Terebilin, A.V.; Stryukov, V.A.

1987-01-01

In order to evaluate beam utilization efficiency, measure the radiation yield, and determine the cost effectiveness of the new technologies, it is necessary to know the radiation power of the electron beam absorbed by the reacting medium. To measure the electron-beam power the authors designed, built, and tested a radiation detector combining a Faraday cylinder with a continuous-flow calorimeter. The construction of the detector is shown. The radiation detector was tested on a number of electron accelerators. The beam-power and mean-electron-energy measurement results for the LUE-8M accelerator with 8 MeV maximum electron energy are given

Emission of medium-heavy fragments in asymetric heavy ion collisions at intermediate and relativistic incident energies

International Nuclear Information System (INIS)

Milkau, T.U.E.

1991-11-01

For the study of the emission of medium-heavy fragments in asymmetric heavy ion collisions a series of experiments was performed and thereby following systems at intermediate and relativistic incident energies studied: 84 Kr+ 197 Au at E/A=35 MeV, 40 Ar+ 197 Au at E/A=30 MeV, respectively 220 MeV, and 12 C+ 197 Au at E/A=99 MeV, 301 MeV, 601 MeV, respectively 1105 MeV. In the experiments highly resolving detector telescopes with low thresholds were applied to the measurement of the energy and angular distributions of the medium-heavy fragments. The spectra were analyzed in the picture of longitudinally moving sources. Thereby beyond the production cross sections the angular distributions, the decreasement parameters in the high-energetic region of the energy spectra, and the position of the maxima were determined as characteristic parameters. The following picture resulted: The production cross sections for medium-heavy fragments showed a steep increasement and then a saturation, but with a strong projectile dependence. The charge distributions could be described by a power law, the parameter of which showed a universal dependence on the total incident energy. In the angular distributions the transition from an anisotropic emission at low energies to an isotropic emission from a nearly resting source at relativistic energies was distinctly to be recognized. The decreasement parameters of the energy distribution increased - for different projectiles differently strongly - logarithmically with growing incident energy. And the maxima of the energy distribution travelled with growing incident energy to smaller and smaller fragment energies. From this systematics a schematic model of the fragmentation can be obtained. (orig./HSI) [de

Low-energy electron emitters for targeted radiotherapy of small tumours

International Nuclear Information System (INIS)

Bernhardt, Peter; Forssell-Aronsson, Eva; Jacobsson, Lars; Skarnemark, Gunnar

2001-01-01

The possibility of using electron emitters to cure a cancer with metastatic spread depends on the energy of the emitted electrons. Electrons with high energy will give a high, absorbed dose to large tumours, but the absorbed dose to small tumours or single tumour cells will be low, because the range of the electrons is too long. The fraction of energy absorbed within the tumour decreases with increasing electron energy and decreasing tumour size. For tumours smaller than 1 g, the tumour-to-normal-tissue mean absorbed dose-rate ratio, TND, will be low, e.g. for 131 I and 90 Y, because of the high energy of the emitted electrons. For radiotherapy of small tumours, radionuclides emitting charged particles with short ranges (a few m u m ) are required. A mathematical model was constructed to evaluate the relation between TND and electron energy, photon-to-electron energy ratio, p/e, and tumour size. Criteria for the selection of suitable radionuclides for the treatment of small tumours were defined based on the results of the TND model. In addition, the possibility of producing such radionuclides and their physical and chemical properties were evaluated. Based on the mathematical model, the energy of the emitted electrons should be = 40 keV for small tumours ( 58m Co, 103m Rh, 119 Sb, 161 Ho, and 189m Os. All of these nuclides by internal transition or electron capture, which yields conversion and Auger electrons, and it should be possible to produce most of them in therapeutic amounts. The five low-energy electron-emitting radionuclides identified may be relevant in the radiation treatment of small tumours, especially if bound to internalizing radiopharmaceuticals

High energy electron beam inactivation of lactate dehydrogenase suspended in different aqueous media

International Nuclear Information System (INIS)

Hategan, A.; Popescu, A.; Butan, C.; Oproiu, C.; Hategan, D.; Morariu, V.V.

1999-01-01

The direct and indirect effects of 5 MeV electron beam irradiation in the range (0-400 Gy) at 20 degC, 0 degC, -3 degC and -196 degC, as well as the influence of the aqueous suspending medium (ultrapure water and heavy water) on the total enzymatic activity of lactate dehydrogenase (LDH) have been studied. Our results showed an exponential decrease on the enzymatic activity of irradiated LDH, at all irradiation temperatures, independently of the direct or indirect action of radiation. The temperature gradient used to lower the temperature of the samples to -196 degC drastically influences the results. Freeze-thawing in two steps down to -196 degC protects LDH to radiation, in the dose range used. The data obtained here inform on the high energy electrons effects on the enzymatic activity loss during irradiation and during thawing, when the subsequent growth of the water crystals influences the three dimensional structure of the enzyme. A 99.98% concentration of D 2 O in the suspending medium of the enzyme decreases the global enzymatic activity, but reduces the rate of radiation inactivation of the enzyme. The rate of radiation inactivation of the enzyme suspended in ultrapure water is reduced when compared to the enzyme suspended in bidistilled water, but compared to the D 2 O suspended enzyme is lightly increased. (author)

Treatment of foods with 'soft-electrons' (low-energy electrons)

Energy Technology Data Exchange (ETDEWEB)

Hayashi, Toru [Japan International Research Center for Agricultural Sciences (JIRCAS), Tsukuba, Ibaraki (Japan); Todoriki, Setsuko [National Food Research Institute (NFRI), Tsukuba, Ibaraki (Japan)

2003-02-01

Electrons with energies of 300 keV or lower were defined as soft-electrons'. Soft-electrons can eradicate microorganisms residing on the surface of grains, pulses, spices, dehydrated vegetables, tea leaves and seeds, and reduce their microbial loads to levels lower than 10 CFU/g with little quality deterioration. Soft-electrons can inactivate insect pests infesting grains and pulses and inhibit sprouting of potatoes. (author)

Nuclear medium effects in the evaluation of Callan Gross relation

International Nuclear Information System (INIS)

Zaidi, F.; Haider, H.; Athar, M. Sajjad; Singh, S.K.

2015-01-01

JLab has recently measured F 1 (x) and F 2 (x) structure functions separately as well as studied the difference F 2 (x) - 2 xF 1 (x) (Callan-Gross relation) using electron-nucleus deep inelastic scattering (DIS) in the energy region of 2-6 GeV of the electron beam. Theoretically, it is important to understand nuclear medium effects for a fundamental process eN → eX (N is the nucleon and X is jet of hadrons) taking place with a nucleon bound inside the nucleus. Generally, nuclear medium effects in the DIS region are understood due to shadowing and antishadowing effects, mesonic cloud contributions, Fermi motion and binding energy etc. In the present paper we have studied nuclear medium effects in microscopic model using relativistic nucleon spectral function to describe nucleon momentum distribution. The Fermi motion, binding energy effect and nucleon-nucleon correlations are taken into account using spectral functions. The spectral functions that describe energy and momentum distribution of nucleon is obtained by using the Lehmann's representation for the relativistic nucleon propagator and nuclear many body theory is used to calculate it for an interacting Fermi sea in nuclear matter. A local density approximation is then applied to translate these results to a finite nucleus. We have taken into account pion and rho mesons cloud contributions which are found to have important contribution in the intermediate region of Bjorken variable x. Furthermore, shadowing and antishadowing effects are also taken into account using phenomenological model of Kulagin and Petti. Numerical evaluation have been performed both at the leading order (LO) and next-to-leading order (NLO)

Tantalum surface oxidation: Bond relaxation, energy entrapment, and electron polarization

Energy Technology Data Exchange (ETDEWEB)

Guo, Yongling [Key Laboratory of Low-Dimensional Materials and Application Technologies (Ministry of Education), Hunan Provincial Key Laboratory of Thin Film Materials and Devices, Faculty of Materials Science and Engineering, Xiangtan University, Hunan 411105 (China); Bo, Maolin [Yangtze Normal University, College of Mechanical and Electrical Engineering, Chongqing 408100 (China); Wang, Yan [School of Information and Electronic Engineering, Hunan University of Science and Technology, Hunan 411201 (China); Liu, Yonghui [Key Laboratory of Low-Dimensional Materials and Application Technologies (Ministry of Education), Hunan Provincial Key Laboratory of Thin Film Materials and Devices, Faculty of Materials Science and Engineering, Xiangtan University, Hunan 411105 (China); Sun, Chang Q. [NOVITAS, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Huang, Yongli, E-mail: huangyongli@xtu.edu.cn [Key Laboratory of Low-Dimensional Materials and Application Technologies (Ministry of Education), Hunan Provincial Key Laboratory of Thin Film Materials and Devices, Faculty of Materials Science and Engineering, Xiangtan University, Hunan 411105 (China)

2017-02-28

Graphical abstract: The bond, electron and energy relaxation result in core level energy shift, local densification, quantum entrapment and electron polarization of bonding electrons. - Highlights: • Increasing the oxygen coverage lowers the adsorption energy associated with lattice reconstruction. • Electrons transfer from Ta surface atoms to sp-hydrated oxygen, creating dipole moment that decreases the work function. • Oxygen chemisorption modified valence density-of-state (DOS) for Ta with four excessive DOS features: O−Ta bonding, O{sup 2−} lone pairs, Ta+ electron holes, and the lone-pair polarized Ta dipoles. • The bond, electron and energy relaxation between surface undercoordinated atoms are responsible for core level energy shift, local densification, quantum entrapment and electron polarization of bonding electrons. - Abstract: A combination of photoelectron spectrometric analysis and density functional theory calculations has enabled reconciliation of the bond-energy-electron relaxation for the Ta(100, 110, 111) surfaces chemisorbed with oxygen at different coverages. Results show that increasing oxygen coverage lowers the adsorption energy associated with lattice reconstruction. Valence electrons transfer from Ta surface atoms to oxygen to create four excessive DOS features in terms of O−Ta bonding, lone pairs of oxygen, Ta{sup +} electron holes, and polarized Ta dipoles. Oxidation proceeds in the following dynamics: oxygen gets electrons from two neighboring Ta atoms left behind Ta{sup +}; the sp{sup 3}-orbital hybridization takes place with additional two electron lone pairs, the lone pairs polarize the other two Ta neighbors becoming dipoles. X-ray photoelectron spectral analysis results in the 4f binding energy of an isolated Ta atom and its shift upon bond formation and oxidation. Exercises provide not only a promising numerical approach for the quantitative information about the bond and electronic behavior but also consistent

Tantalum surface oxidation: Bond relaxation, energy entrapment, and electron polarization

International Nuclear Information System (INIS)

Guo, Yongling; Bo, Maolin; Wang, Yan; Liu, Yonghui; Sun, Chang Q.; Huang, Yongli

2017-01-01

Graphical abstract: The bond, electron and energy relaxation result in core level energy shift, local densification, quantum entrapment and electron polarization of bonding electrons. - Highlights: • Increasing the oxygen coverage lowers the adsorption energy associated with lattice reconstruction. • Electrons transfer from Ta surface atoms to sp-hydrated oxygen, creating dipole moment that decreases the work function. • Oxygen chemisorption modified valence density-of-state (DOS) for Ta with four excessive DOS features: O−Ta bonding, O"2"− lone pairs, Ta+ electron holes, and the lone-pair polarized Ta dipoles. • The bond, electron and energy relaxation between surface undercoordinated atoms are responsible for core level energy shift, local densification, quantum entrapment and electron polarization of bonding electrons. - Abstract: A combination of photoelectron spectrometric analysis and density functional theory calculations has enabled reconciliation of the bond-energy-electron relaxation for the Ta(100, 110, 111) surfaces chemisorbed with oxygen at different coverages. Results show that increasing oxygen coverage lowers the adsorption energy associated with lattice reconstruction. Valence electrons transfer from Ta surface atoms to oxygen to create four excessive DOS features in terms of O−Ta bonding, lone pairs of oxygen, Ta"+ electron holes, and polarized Ta dipoles. Oxidation proceeds in the following dynamics: oxygen gets electrons from two neighboring Ta atoms left behind Ta"+; the sp"3-orbital hybridization takes place with additional two electron lone pairs, the lone pairs polarize the other two Ta neighbors becoming dipoles. X-ray photoelectron spectral analysis results in the 4f binding energy of an isolated Ta atom and its shift upon bond formation and oxidation. Exercises provide not only a promising numerical approach for the quantitative information about the bond and electronic behavior but also consistent insight into the

High-energy electron irradiation of NdFeB permanent magnets: Dependence of radiation damage on the electron energy

Energy Technology Data Exchange (ETDEWEB)

Bizen, Teruhiko [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan)]. E-mail: bizen@spring8.or.jp; Asano, Yoshihiro [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); RIKEN SPring-8 Center, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Marechal, Xavier-Marie [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Seike, Takamitsu [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Aoki, Tsuyoshi [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Fukami, Kenji [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Hosoda, Naoyasu [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Yonehara, Hiroto [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Takagi, Tetsuya [JASRI SPring-8, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Hara, Toru [RIKEN SPring-8 Center, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Tanaka, Takashi [RIKEN SPring-8 Center, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Kitamura, Hideo [RIKEN SPring-8 Center, 1-1-1 Kouto Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan)

2007-05-11

High-energy electron-beam bombardment of Nd{sub 2}Fe{sub 14}B-type permanent magnets induces radiation damage characterized by a drop in the magnetic field. Experiments carried out at the SPring-8 booster synchrotron, with 4, 6, and 8 GeV electrons, show that the drop in magnetic field is energy dependent. Electromagnetic shower simulations suggest that most of the radiation damage happens in a small region around the irradiation axis, and that the contribution of neutrons with large scattering angles or with low energies to the magnetic field change is small.

High-energy electron irradiation of NdFeB permanent magnets: Dependence of radiation damage on the electron energy

International Nuclear Information System (INIS)

Bizen, Teruhiko; Asano, Yoshihiro; Marechal, Xavier-Marie; Seike, Takamitsu; Aoki, Tsuyoshi; Fukami, Kenji; Hosoda, Naoyasu; Yonehara, Hiroto; Takagi, Tetsuya; Hara, Toru; Tanaka, Takashi; Kitamura, Hideo

2007-01-01

High-energy electron-beam bombardment of Nd 2 Fe 14 B-type permanent magnets induces radiation damage characterized by a drop in the magnetic field. Experiments carried out at the SPring-8 booster synchrotron, with 4, 6, and 8 GeV electrons, show that the drop in magnetic field is energy dependent. Electromagnetic shower simulations suggest that most of the radiation damage happens in a small region around the irradiation axis, and that the contribution of neutrons with large scattering angles or with low energies to the magnetic field change is small

Medium energy nuclear physics research

International Nuclear Information System (INIS)

Peterson, G.A.; Dubach, J.F.; Hicks, R.S.; Miskimen, R.A.

1988-09-01

The UMass group has concentrated on using electromagnetic probes, particularly the electron in high-energy scattering experiments at the Stanford Liner Accelerator Center (SLAC). Plans are also being made for high energy work at the Continuous Beam Accelerator Facility (CEBAF). The properties of this accelerator should permit a whole new class of coincidence experiments to be carried out. At SLAC UMass has made major contributions toward the plans for a cluster-jet gas target and detector system at the 16 GeV PEP storage ring. For the future CEBAF accelerator, tests were made of the feasibility of operating wire drift chambers in the vicinity of a continuous electron beam at the University Illinois microtron. At the same time a program of studies of the nuclear structure of more complex nuclei has been continued at the MIT-Bates Linear Accelerator Center and in Amsterdam at the NIKHEF-K laboratory. At the MIT-Bates Accelerator, because of an unforeseen change in beam scheduling as a result of problems with the T 20 experiment, the UMass group was able to complete data acquisition on experiments involving 180 degrees elastic magnetic scattering on 117 Sn and 41 Ca. A considerable effort has been given to preparations for a future experiment at Bates involving the high-resolution threshold electrodisintegration of the deuteron. The use of these chambers should permit a high degree of discrimination against background events in the measurement of the almost neutrino-like small cross sections that are expected. In Amsterdam at the NIKHEF-K facility, single arm (e,e') measurements were made in November of 1987 on 10 B in order to better determine the p 3/2 wave function from the transition from the J pi = 3 + ground state to the O + excited state at 1.74 MeV. In 1988, (e,e'p) coincidence measurements on 10 B were completed. The objective was to obtain information on the p 3/2 wave function by another means

Application of pulse power technology to ultra high energy electron accelerators

International Nuclear Information System (INIS)

Nation, J.A.

1989-01-01

The author presents in this paper a review of the application of pulse power technology to the development of high gradient electron accelerators. The technology demands are relatively modest compared to the ultra high power technology used for inertial confinement fusion drivers. With the advent of magnetic switching intense electron beams can be generated with a sufficiently high repetition rate to be of interest for high energy electron accelerator driver applications. Most of the techniques considered rely on the excitation of large amplitude waves on the beams. Within this framework there are two broad categories of accelerator, those in which the waves are directly excited in and supported by the medium and, secondly, those where the waves are used to generate radiofrequency signals which are then coupled via structures to the beam being accelerated. In what follows we shall consider both approaches. Present-day pulse power technology limits pulse durations to about 100 nsec. Consequently, if these sources are to be used, we will need to use high group velocity structures to avoid the need for short accelerator module lengths. An advantage of the short pulse duration is that the available acceleration voltage gradient increases compared to that obtained using conventional rf drivers. 19 references, 9 figures, 1 table

Enhanced energy deposition symmetry by hot electron transport

International Nuclear Information System (INIS)

Wilson, D.; Mack, J.; Stover, E.; VanHulsteyn, D.; McCall, G.; Hauer, A.

1981-01-01

High energy electrons produced by resonance absorption carry the CO 2 laser energy absorbed in a laser fusion pellet. The symmetrization that can be achieved by lateral transport of the hot electrons as they deposit their energy is discussed. A K/sub α/ experiment shows a surprising symmetrization of energy deposition achieved by adding a thin layer of plastic to a copper sphere. Efforts to numerically model this effect are described

Derivation of electron and photon energy spectra from electron beam central axis depth dose curves

Energy Technology Data Exchange (ETDEWEB)

Deng Jun [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305 (United States)]. E-mail: jun@reyes.stanford.edu; Jiang, Steve B.; Pawlicki, Todd; Li Jinsheng; Ma, C.M. [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305 (United States)

2001-05-01

A method for deriving the electron and photon energy spectra from electron beam central axis percentage depth dose (PDD) curves has been investigated. The PDD curves of 6, 12 and 20 MeV electron beams obtained from the Monte Carlo full phase space simulations of the Varian linear accelerator treatment head have been used to test the method. We have employed a 'random creep' algorithm to determine the energy spectra of electrons and photons in a clinical electron beam. The fitted electron and photon energy spectra have been compared with the corresponding spectra obtained from the Monte Carlo full phase space simulations. Our fitted energy spectra are in good agreement with the Monte Carlo simulated spectra in terms of peak location, peak width, amplitude and smoothness of the spectrum. In addition, the derived depth dose curves of head-generated photons agree well in both shape and amplitude with those calculated using the full phase space data. The central axis depth dose curves and dose profiles at various depths have been compared using an automated electron beam commissioning procedure. The comparison has demonstrated that our method is capable of deriving the energy spectra for the Varian accelerator electron beams investigated. We have implemented this method in the electron beam commissioning procedure for Monte Carlo electron beam dose calculations. (author)

Ultra-low-energy wide electron exposure unit

International Nuclear Information System (INIS)

Yonago, Akinobu; Oono, Yukihiko; Tokunaga, Kazutoshi; Kishimoto, Junichi; Wakamoto, Ikuo

2001-01-01

Heat and ultraviolet ray processes are used in surface dryness of paint, surface treatment of construction materials and surface sterilization of food containers. A process using a low-energy wide-area electron beam (EB) has been developed that features high speed and low drive cost. EB processing is not widespread in general industry, however, due to high equipment cost and difficult maintenance. We developed an ultra-low-energy wide-area electron beam exposure unit, the Mitsubishi Wide Electron Exposure Unit (MIWEL) to solve these problems. (author)

Energy deposition model for low-energy electrons (10-10 000 eV) in air

International Nuclear Information System (INIS)

Roldan, A.; Perez, J.M.; Williart, A.; Blanco, F.; Garcia, G.

2004-01-01

An energy deposition model for electrons in air that can be useful in microdosimetric applications is presented in this study. The model is based on a Monte Carlo simulation of the single electron scattering processes that can take place with the molecular constituents of the air in the energy range 10-10 000 eV. The input parameters for this procedure have been the electron scattering cross sections, both differential and integral. These parameters were calculated using a model potential method which describes the electron scattering with the molecular constituent of air. The reliability of the calculated integral cross section values has been evaluated by comparison with direct total electron scattering cross-section measurements performed by us in a transmission beam experiment. Experimental energy loss spectra for electrons in air have been used as probability distribution functions to define the electron energy loss in single collision events. The resulting model has been applied to simulate the electron transport through a gas cell containing air at different pressures and the results have been compared with those observed in the experiments. Finally, as an example of its applicability to dosimetric issues, the energy deposition of 10 000 eV by means of successive collisions in a free air chamber has been simulated

Nonlinear dynamics of circularly polarized laser pulse propagating in a magnetized plasma with superthermal ions and mixed nonthermal high-energy tail electrons distributions

International Nuclear Information System (INIS)

Etemadpour, R.; Dorranian, D.; Sepehri Javan, N.

2016-01-01

The nonlinear dynamics of a circularly polarized laser pulse propagating in the magnetized plasmas whose constituents are superthermal ions and mixed nonthermal high-energy tail electrons is studied theoretically. A nonlinear equation which describes the dynamics of the slowly varying amplitude is obtained using a relativistic two-fluid model. Based on this nonlinear equation and taking into account some nonlinear phenomena such as modulational instability, self-focusing and soliton formation are investigated. Effect of the magnetized plasma with superthermal ions and mixed nonthermal high-energy tail electrons on these phenomena is considered. It is shown that the nonthermality and superthermality of particles can substantially change the nonlinearity of medium.

Nonlinear dynamics of circularly polarized laser pulse propagating in a magnetized plasma with superthermal ions and mixed nonthermal high-energy tail electrons distributions

Energy Technology Data Exchange (ETDEWEB)

Etemadpour, R.; Dorranian, D., E-mail: doran@srbiau.ac.ir [Laser Laboratory, Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Sepehri Javan, N. [Department of Physics, University of Mohaghegh Ardabili, P.O. Box 179, Ardabil (Iran, Islamic Republic of)

2016-05-15

The nonlinear dynamics of a circularly polarized laser pulse propagating in the magnetized plasmas whose constituents are superthermal ions and mixed nonthermal high-energy tail electrons is studied theoretically. A nonlinear equation which describes the dynamics of the slowly varying amplitude is obtained using a relativistic two-fluid model. Based on this nonlinear equation and taking into account some nonlinear phenomena such as modulational instability, self-focusing and soliton formation are investigated. Effect of the magnetized plasma with superthermal ions and mixed nonthermal high-energy tail electrons on these phenomena is considered. It is shown that the nonthermality and superthermality of particles can substantially change the nonlinearity of medium.

Electron and Photon ID

CERN Document Server

Hryn'ova, Tetiana; The ATLAS collaboration

2017-01-01

The identification of prompt photons and the rejection of background coming mostly from photons from hadron decays relies on the high granularity of the ATLAS calorimeter. The electron identification used in ATLAS for run 2 is based on a likelihood discrimination to separate isolated electron candidates from candidates originating from photon conversions, hadron misidentification and heavy flavor decays. In addition, isolation variables are used as further handles to separate signal and background. Several methods are used to measure with data the efficiency of the photon identification requirements, to cover a broad energy spectrum. At low energy, photons from radiative Z decays are used. In the medium energy range, similarities between electrons and photon showers are exploited using Z->ee decays. At high energy, inclusive photon samples are used. The measurement of the efficiencies of the electron identification and isolation cuts are performed with the data using tag and probe techniques with large statis...

Electron energy distribution from intense electron beams in the upper mesosphere and lower thermosphere

International Nuclear Information System (INIS)

Martinez-Sanchez, M.; Cheng, Wai; Dvore, D.; Zahniser, M.S.

1992-01-01

A model was developed to calculate the electron energy spectrum created by an electron beam in the upper atmosphere. A significant feature of the model is the inclusion of the effects of electron-electron collisions which are important at high beam intensity when the ratio of the electron to ambient gas density is high. Comparing the calculated results for a 2.6-kV, 20-A beam at 110-km altitude from models with and without the electron-electron collision term, the electron-electron collisions have the effect of smoothing out the electron spectrum in the low-energy region ( 2 and O 2 are filled in, resulting in an increase in the calculated production rate of these species compared with model calculations that neglect this effect

Energy spectra variations of high energy electrons in magnetic storms observed by ARASE and HIMAWARI

Science.gov (United States)

Takashima, T.; Higashio, N.; Mitani, T.; Nagatsuma, T.; Yoshizumi, M.

2017-12-01

The ARASE spacecraft was launched in December 20, 2016 to investigate mechanisms for acceleration and loss of relativistic electrons in the radiation belts during space storms. The six particle instruments with wide energy range (a few eV to 10MeV) are onboard the ARASE spacecraft. Especially, two particle instruments, HEP and XEP observe high energy electron with energy range from 70keV to over 10Mev. Those instruments observed several geomagnetic storms caused by coronal hole high speed streams or coronal mass ejections from March in 2017. The relativistic electrons in the outer radiation belt were disappeared/increased and their energy spectra were changed dynamically in some storms observed by XEP/HEP onboard the ARASE spacecraft. In the same time, SEDA-e with energy range 200keV-4.5MeV for electron on board the HIMAWARI-8, Japanese weather satellite on GEO, observed increase of relativistic electron in different local time. We will report on energy spectra variations of high energy electrons including calibrations of differential flux between XEP and HEP and discuss comparisons with energy spectra between ARAE and HIMAWARI that observed each storm in different local time.

Energy Efficiency Market Report 2013: Market Trends and Medium-Term Prospects

Energy Technology Data Exchange (ETDEWEB)

NONE

2013-07-01

Energy efficiency has been referred to as a ''hidden fuel'', one that extends energy supplies, increases energy security, lowers carbon emissions and generally supports sustainable economic growth. Yet it is hiding in plain sight: in 2011, investments in the energy efficiency market globally were at a similar scale to those in renewable energy or fossil-fuel power generation. The Energy Efficiency Market Report provides a practical basis for understanding energy efficiency market activities, a review of the methodological and practical challenges associated with measuring the market and its components, and statistical analysis of energy efficiency and its impact on energy demand. It also highlights a specific technology sector in which there is significant energy efficiency market activity, in this instance appliances and ICT. The report presents a selection of country case studies that illustrate current energy efficiency markets in specific sectors, and how they may evolve in the medium term. The energy efficiency market is diffuse, varied and involves all energy-consuming sectors of the economy. A comprehensive overview of market activity is complicated by the challenges associated with quantifying the components of the market and the paucity of comparable reported data. This report underscores how vital high-quality and timely energy efficiency data is to understanding this market.

Medium modifications with recoil polarization

International Nuclear Information System (INIS)

Brand, J.F.J. van den; Ent, R.

1994-01-01

The authors show that the virtual Compton scattering process allows for a precise study of the off-shell electron-nucleon vertex. In a separable model, they show the sensitivity to new unconstrained structure functions of the nucleon, beyond the usual Dirac and Pauli form factors. In addition, they show the sensitivity to bound nucleon form factors using the reaction 4He(rvec e,e',rvec p) 3 H. A nucleon embedded in a nucleus represents a complex system. Firstly, the bound nucleon is necessarily off-shell and in principle a complete understanding of the dynamical structure of the nucleon is required in order to calculate its off-shell electromagnetic interaction. Secondly, one faces the possibility of genuine medium effects, such as for example quark-exchange contributions. Furthermore, the electromagnetic coupling to the bound nucleon is dependent on the nuclear dynamics through the self-energy of the nucleon in the nuclear medium

Near-field thermal upconversion and energy transfer through a Kerr medium.

Science.gov (United States)

Khandekar, Chinmay; Rodriguez, Alejandro W

2017-09-18

We present an approach for achieving large Kerr χ (3) -mediated thermal energy transfer at the nanoscale that exploits a general coupled-mode description of triply resonant, four-wave mixing processes. We analyze the efficiency of thermal upconversion and energy transfer from mid- to near-infrared wavelengths in planar geometries involving two slabs supporting far-apart surface plasmon polaritons and separated by a nonlinear χ (3) medium that is irradiated by externally incident light. We study multiple geometric and material configurations and different classes of intervening mediums-either bulk or nanostructured lattices of nanoparticles embedded in nonlinear materials-designed to resonantly enhance the interaction of the incident light with thermal slab resonances. We find that even when the entire system is in thermodynamic equilibrium (at room temperature) and under typical drive intensities ~ W/μm 2 , the resulting upconversion rates can approach and even exceed thermal flux rates achieved in typical symmetric and non-equilibrium configurations of vacuum-separated slabs. The proposed nonlinear scheme could potentially be exploited to achieve thermal cooling and refrigeration at the nanoscale, and to actively control heat transfer between materials with dramatically different resonant responses.

An energy monitor for electron accelerators

Energy Technology Data Exchange (ETDEWEB)

Geske, G. (Friedrich-Schiller-Universitaet, Jena (German Democratic Republic). Klinik und Poliklinik des Bereiches Medizin)

1990-09-01

A monitor useful for checks of the energy selector scale of medical electron accelerators was developed and tested. It consists of a linear array of flat ionization chambers sandwiched between absorber plates of low-Z material. The first chamber at the electron beam entrance may be used to produce a reference signal S{sub r}, if not another suitable reference signal is taken. The following chambers are electrically connected and deliver the measuring signal S{sub m}. A clinical dosimeter can be used for recording current or charge. The energy-dependent electron range parameters R{sub p}, R{sub 50} and R{sub 80} in water vary as linear functions of the ratio reference singal/measuring signal. The best linear fit was obtained for the half value layer R{sub 50}. Three types of the energy monitor are described, and experimental results obtained with a linear accelerator and a betatron between 5 and 25 MeV are reported. Uncertainties for checks of R{sub 50} with a calibrated energy monitor were not larger than 1 to 2 mm. Theoretical considerations by a computer model support these results. (orig./HP).

An intercomparison of medium energy cross-section codes

International Nuclear Information System (INIS)

Pearlstein, S.

1988-05-01

Five medium energy proton reaction cases are selected for benchmarking nuclear model codes. The quantities calculated are isotopic activation yields for 180 MeV protons on Al and 40-200 MeV protons on Co, and double differential neutron emission spectra from Al, Zr-90 and Pb-208 for 35, 80, 160, 318, and 800 presented consist of three types: a closed form preequilibrium plus evaporation model, an intranuclear-cascade and evaporation model, and a model relying on nuclear systematics. The characteristics of each code are described. There are orders of magnitude differences in the time for each type of code to calculate neutron emission spectra, with codes using systematics, preequilibrium and intranuclear-cascade models requiring seconds, minutes and hours, respectively. Calculations are not compared with experiment in this initial study. For double differential neutron emission spectra, there is good overall agreement in magnitude among the different types of codes at forward angles. Differences where they occur at forward angles are greatest for the mid-energy neutrons emitted. At back angles the incident energy at which the best overall agreement is obtained is 160 MeV and the material for which the best overall agreement is obtained is Al. 4 refs., 7 tabs

Coherence in electron energy loss spectrometry

International Nuclear Information System (INIS)

Schattschneider, P.; Werner, W.S.M.

2005-01-01

Coherence effects in electron energy loss spectrometry (EELS) and in energy filtering are largely neglected although they occur frequently due to Bragg scattering in crystals. We discuss how coherence in the inelastically scattered wave field can be described by the mixed dynamic form factor (MDFF), and how it relates to the density matrix of the scattered electrons. Among the many aspects of 'inelastic coherence' are filtered high-resolution images, dipole-forbidden transitions, coherence in plasma excitations, errors in chemical microanalysis, coherent double plasmons, and circular dichroism

The operational procedure of an electron beam accelerator

International Nuclear Information System (INIS)

Lee, Byung Cheol; Choi, Hwa Lim; Yang, Ki Ho; Han, Young Hwan; Kim, Sung Chan

2008-12-01

The KAERI(Korea Atomic Energy of Research Institute) high-power electron beam irradiation facility, operating at the energies between 0.3 MeV and 10 MeV, has provided irradiation services to users in industries, universities, and institute in various fields. This manual is for the operation of an electron beam which is established in KAERI, and describes elementary operation procedures of electron beam between 0.3 Mev and 10 MeV. KAERI Electron Accelerator facility(Daejeon, Korea) consists of two irradiators: one is a low-energy electron beam irradiator operated by normal conducting RF accelerator, the other is medium-energy irradiator operated by superconducting RF accelerator. We explain the check points of prior to operation, operation procedure of this facility and the essential parts of electron beam accelerator

The operational procedure of an electron beam accelerator

Energy Technology Data Exchange (ETDEWEB)

Lee, Byung Cheol; Choi, Hwa Lim; Yang, Ki Ho; Han, Young Hwan; Kim, Sung Chan

2008-12-15

The KAERI(Korea Atomic Energy of Research Institute) high-power electron beam irradiation facility, operating at the energies between 0.3 MeV and 10 MeV, has provided irradiation services to users in industries, universities, and institute in various fields. This manual is for the operation of an electron beam which is established in KAERI, and describes elementary operation procedures of electron beam between 0.3 Mev and 10 MeV. KAERI Electron Accelerator facility(Daejeon, Korea) consists of two irradiators: one is a low-energy electron beam irradiator operated by normal conducting RF accelerator, the other is medium-energy irradiator operated by superconducting RF accelerator. We explain the check points of prior to operation, operation procedure of this facility and the essential parts of electron beam accelerator.

Low-energy positron and electron diffraction and positron-stimulated secondary electron emission from Cu(100)

International Nuclear Information System (INIS)

Weiss, A.H.

1983-01-01

The results of two series of experiments are reported. In the first, an electrostatically guided beam of low-energy (40-400 eV) positrons, delta/sub p/ was used to study low-energy positron diffraction (LEPD) from a Cu(100) surface under ultrahigh-vacuum conditions. Low-energy electron diffraction (LEED) data were obtained from the same sample in the same apparatus. Comparison of LEPD and LEED intensity versus energy data with model calculations made using computer programs developed by C.B. Duke and collaborators indicated that: LEPD data is adequately modeled using potentials with no exchange-correlation term. The inelastic mean free path, lambda/sub ee/, is shorter for positrons than for electrons at low (< approx.80 eV). LEED is better than LEPD at making a determination of the first-layer spacing of Cu(100) for the particular data set reported. In the second set of experiments, the same apparatus and sample were used to compare positron- and electron-stimulated secondary-electron emission (PSSEE and ESSEE). The results were found to be consistent with existing models of secondary-electron production for metals. The energy distributions of secondary-electrons had broad low-energy (<10 eV) peaks for both positron and electron stimulation. But the PSEE distribution showed no elastic peak. Measurements of secondary-electron angular distributions, found to be cosine-like in both the PSSEE and ESSEE case, were used to obtain total secondary yield ratios, delta, at four beam energies ranging from 40-400 eV. The secondary yield ratio for primary positrons and the yield for primary electrons, delta/sub e/, were similar at these energies. For 400-eV primary particles the secondary yields were found to be delta/sub p/ = 0.94 +/- 0.12 and delta/sub e/ = 0.94 +/- 0./12, giving a ratio of unity for positron-stimulated secondary yield to electron-stimulated secondary yield

Beacon-S TM: Non-uniform attenuation correction for SPECT imaging. The new medium-energy transmission device for AXIS and IRIX

International Nuclear Information System (INIS)

Daniel Gagnon, D.

1999-01-01

The paper presents new medium-energy transmission device for SPECT imaging. Beacon-S includes a 356-keV medium energy 133 Ba source with a 10.54-year half-life. Beacon-S provide high-resolution and high-contrast transmission scans. The higher energy of the gamma substantially improves the transmission contrast for larger patients by virtue of better penetration through the body

Fiscal 1999 survey report on long-term energy technological strategies and the like. Long-term energy technological strategy survey (Medium-term energy technological strategy survey); 1999 nendo choki energy gijutsu senryaku nado ni kansuru chosa hokokusho. Choki energy gijutsu senryaku chosa (chuki energy gijutsu senryaku chosa)

Energy Technology Data Exchange (ETDEWEB)

NONE

2000-03-01

Energy strategies to be implemented under the New Sunshine Program by around 2010 have been compiled, with nation's industrial technological strategies, long-term energy outlook, and the like taken into consideration. The present survey aims to work out medium-term energy technological strategies. In Chapter 2, by conducting studies on the state of energy strategies in the national industry technological strategies as primarily compiled, long-term energy supply and demand outlook, and the history so far of the New Sunshine Program, and social conditions surrounding energy/environmental technologies and energy conditions are arranged in order and then analyzed with a view to deriving social needs. In Chapter 3, in view of the derived social needs, medium-term energy technological strategies are broken down into strategic target details, based on the important regions and major and minor strategic targets of the national industry technological strategies. In Chapter 4, medium-term energy technological strategies are worked out. In Chapter 5, 'basic ideas,' 'measures for promoting technology development,' 'return of the fruits to society' are mentioned as the methods of realizing the strategies. In Chapter 6, surveys and researches are summarized, and future development is predicted. (NEDO)

Modeling power electronics and interfacing energy conversion systems

CERN Document Server

Simões, Marcelo Godoy

2017-01-01

Discusses the application of mathematical and engineering tools for modeling, simulation and control oriented for energy systems, power electronics and renewable energy. This book builds on the background knowledge of electrical circuits, control of dc/dc converters and inverters, energy conversion and power electronics. The book shows readers how to apply computational methods for multi-domain simulation of energy systems and power electronics engineering problems. Each chapter has a brief introduction on the theoretical background, a description of the problems to be solved, and objectives to be achieved. Block diagrams, electrical circuits, mathematical analysis or computer code are covered. Each chapter concludes with discussions on what should be learned, suggestions for further studies and even some experimental work.

Electron-energy deposition in skin and thermoluminescence dosimeters

International Nuclear Information System (INIS)

Mei, G.T.Y.

1986-01-01

The primary object of this study was to investigate the relations between dosimeter response and skin dose resulting from beta-particle irradiation. This object was achieved by combining evaluation of beta-source energy spectra, calculation of flux energy spectra, and employment of a Monte-Carlo electron-transport computer program for determination of depth-dose distribution in multislab geometries. Intermediate results from three steps of evaluation were compared individually with experimental data or with other theoretical results and showed excellent agreement. The combined method is applicable for the electron agreement. The combined method is applicable for the electron energy range of 1 keV to 5 MeV for both monoenergetic electrons and energy-distributed electrons. Determination of dosimeter response - skin dose relationships for homogeneous atmospheric beta-particle sources and for two specific configurations of LiF TLD's have been carried out in this study. Information based on these calculations is of value in designing beta-particle dosimeters as well as in assessing potential occupational and public health risks associated with the nuclear power industry

Nuclear structure and reaction studies at medium energies

International Nuclear Information System (INIS)

Hoffmann, G.W.; Ray, R.L.

1990-10-01

This document constitutes the (1988--1991) technical progress report for the ongoing medium energy physics research program supported by the US Department of Energy through special Research Grant FG05-88ER40444. The experiments discussed are conducted at the Los Alamos National Laboratory's (LANL) Clinton P. Anderson Meson Physics Facility (LAMPF), the Alternating Gradient Synchrotron (AGS) facility of the Brookhaven National Laboratory (BNL), and at the Fermi National Accelerator Laboratory (FNAL). The overall motivation for the work discussed in this document is driven by three main objectives: (1) provide hadron-nucleon and hadron-nucleus scattering data which serve to facilitate the study of effective two-body interactions, test (and possibly determine) nuclear structure, and help study reaction mechanisms and dynamics;(2) provide unique, first-of-a-kind ''exploratory'' hadron-nucleus scattering data in the hope that such data will lead to discovery of new phenomena and new physics; and (3) perform precision tests of fundamental interactions, such as rare decay searches, whose observation would imply fundamental new physics

Power Electronics Control of Wind Energy in Distributed Power System

DEFF Research Database (Denmark)

Iov, Florin; Ciobotaru, Mihai; Blaabjerg, Frede

2008-01-01

is to change the electrical power production sources from the conventional, fossil (and short term) based energy sources to renewable energy resources. The other is to use high efficient power electronics in power generation, power transmission/distribution and end-user application. This paper discuss the most...... emerging renewable energy sources, wind energy, which by means of power electronics are changing from being a minor energy source to be acting as an important power source in the energy system. Power electronics is the enabling technology and the presentation will cover the development in wind turbine...... technology from kW to MW, discuss which power electronic solutions are most feasible and used today....

Theoretical interpretation of medium energy nucleon nucleus inelastic scattering

International Nuclear Information System (INIS)

Lagrange, Christian

1970-06-01

A theoretical study is made of the medium energy nucleon-nucleus inelastic scattering (direct interaction), by applying the distorted wave Born approximation such as can be deduced from the paired equation method. It is applied to the interpretation of the inelastic scattering of 12 MeV protons by 63 Cu; this leads us to make use of different sets of wave functions to describe the various states of the target nucleus. We analyze the nature of these states and the shape of the nucleon-nucleus interaction potential, and we compare the results with those obtained from other theoretical and experimental work. (author) [fr

Interplay between bulk medium evolution and (D)GLV energy loss

International Nuclear Information System (INIS)

Molnar, Denes; Sun, Deke

2014-01-01

We study the consistency between high-p T nuclear suppression (R AA ) and elliptic flow (v 2 ) using Gyulassy–Levai–Vitev (GLV) energy loss or a simpler power-law dE/dL formula, for a variety of bulk evolution models. The results generally confirm our earlier work [1] that found suppressed elliptic flow for transversely expanding media. One exception is the set of hydrodynamic solutions used recently [2] by Betz and Gyulassy, which give significantly higher v 2 but unfortunately assume unrealistic bag-model equation of state. On the other hand, we show that covariant treatment of energy loss introduces an interplay between jet direction and hydrodynamic flow of the medium, which largely counteracts elliptic flow suppression caused by transverse expansion

Electron energy recovery system for negative ion sources

International Nuclear Information System (INIS)

Dagenhart, W.K.; Stirling, W.L.

1982-01-01

An electron energy recovery system for negative ion sources is provided. The system, employs crossed electric and magnetic fields to separate the electrons from ions as they are extracted from a negative ion source plasma generator and before the ions are accelerated to their full kinetic energy. With the electric and magnetic fields oriented 90* to each other, the electrons are separated from the plasma and remain at approximately the electrical potential of the generator in which they were generated. The electrons migrate from the ion beam path in a precessing motion out of the ion accelerating field region into an electron recovery region provided by a specially designed electron collector electrode. The electron collector electrode is uniformly spaced from a surface of the ion generator which is transverse to the direction of migration of the electrons and the two surfaces are contoured in a matching relationship which departs from a planar configuration to provide an electric field component in the recovery region which is parallel to the magnetic field thereby forcing the electrons to be directed into and collected by the electron collector electrode. The collector electrode is maintained at a potential slightly positive with respect to the ion generator so that the electrons are collected at a small fraction of the full accelerating supply voltage energy

Electron energy distribution in a weakly ionized plasma

International Nuclear Information System (INIS)

Cesari, C.

1967-03-01

The aim of this work is to determine from both the theoretical and experimental points of view the type of distribution function for the electronic energies existing in a positive-column type cold laboratory plasma having an ionization rate of between 10 -6 and 10 -7 . The theoretical analysis, based on the imperfect Lorentz model and taking into account inelastic collisions is developed from the Boltzmann equation. The experimental method which we have employed for making an electrostatic analysis of the electronic energies makes use of a Langmuir probe used in conjunction with a transistorized electronic device. A comparison between the experimental and theoretical results yields information concerning the mechanisms governing electronic energy transfer on a microscopic scale. (author) [fr

Renewable Energy Systems in the Power Electronics Curriculum

DEFF Research Database (Denmark)

Blaabjerg, Frede; Chen, Zhe; Teodorescu, Remus

2005-01-01

of the most important area is renewable energy systems. This paper will discuss the basic courses for the power electronics curriculum. It will also discuss how to teach power electronic systems efficiently through a projectoriented and problem-based learning approach with Aalborg University in Denmark...... as a full-scale example. Different project examples will be given as well as important laboratories for adjustable speed drives and renewable energy systems which are used at the university are described.......Power Electronics is still an emerging technology and its applications are increasing. The primary function is to convert electrical energy from one stage to another and it is used in many different applications. The power electronics curriculum is multidisciplinary covering fields like devices...

Energy Spread Reduction of Electron Beams Produced via Laser Wake

Energy Technology Data Exchange (ETDEWEB)

Pollock, Bradley Bolt [Univ. of California, San Diego, CA (United States)

2012-01-01

Laser wakefield acceleration of electrons holds great promise for producing ultra-compact stages of GeV scale, high quality electron beams for applications such as x-ray free electron lasers and high energy colliders. Ultra-high intensity laser pulses can be self-guided by relativistic plasma waves over tens of vacuum diffraction lengths, to give >1 GeV energy in cm-scale low density plasma using ionization-induced injection to inject charge into the wake at low densities. This thesis describes a series of experiments which investigates the physics of LWFA in the self-guided blowout regime. Beginning with high density gas jet experiments the scaling of the LWFA-produced electron beam energy with plasma electron density is found to be in excellent agreement with both phenomenological theory and with 3-D PIC simulations. It is also determined that self-trapping of background electrons into the wake exhibits a threshold as a function of the electron density, and at the densities required to produce electron beams with energies exceeding 1 GeV a different mechanism is required to trap charge into low density wakes. By introducing small concentrations of high-Z gas to the nominal He background the ionization-induced injection mechanism is enabled. Electron trapping is observed at densities as low as 1.3 x 10¹⁸ cm^-3 in a gas cell target, and 1.45 GeV electrons are demonstrated for the first time from LWFA. This is currently the highest electron energy ever produced from LWFA. The ionization-induced trapping mechanism is also shown to generate quasi-continuous electron beam energies, which is undesirable for accelerator applications. By limiting the region over which ionization-induced trapping occurs, the energy spread of the electron beams can be controlled. The development of a novel two-stage gas cell target provides the capability to tailor the gas composition in the longitudinal direction, and confine the trapping process to occur only in a

High energy polarized electron beams

International Nuclear Information System (INIS)

Rossmanith, R.

1987-01-01

In nearly all high energy electron storage rings the effect of beam polarization by synchrotron radiation has been measured. The buildup time for polarization in storage rings is of the order of 10 6 to 10 7 revolutions; the spins must remain aligned over this time in order to avoid depolarization. Even extremely small spin deviations per revolution can add up and cause depolarization. The injection and the acceleration of polarized electrons in linacs is much easier. Although some improvements are still necessary, reliable polarized electron sources with sufficiently high intensity and polarization are available. With the linac-type machines SLC at Stanford and CEBAF in Virginia, experiments with polarized electrons will be possible

Electron-ion recombination at low energy

International Nuclear Information System (INIS)

Andersen, L.H.

1993-01-01

The work is based on results obtained with a merged-beams experiment. A beam of electronics with a well characterized density and energy distribution was merged with a fast, monoenergetic ion beam. Results have been obtained for radiative recombination and dielectronic recombination at low relative energies (0 to ∼70eV). The obtained energy resolution was improved by about a factor of 30. High vacuum technology was used to suppress interactions with electrons from the environments. The velocity distribution of the electron beam was determined. State-selective dielectronic-recombination measurements were performable. Recombination processes were studied. The theoretical background for radiative recombination and Kramers' theory are reviewed. The quantum mechanical result and its relation to the semiclassical theory is discussed. Radiative recombination was also measured with several different non-bare ions, and the applicability of the semiclassical theory to non-bare ions was investigated. The use of an effective charge is discussed. For dielectronic recombination, the standard theoretical approach in the isolated resonance and independent-processes approximation is debated. The applicability of this method was tested. The theory was able to reproduce most of the experimental data except when the recombination process was sensitive to couplings between different electronic configurations. The influence of external perturbing electrostatic fields is discussed. (AB) (31 refs.)

Gadgets and Gigawatts - Policies for Energy Efficient Electronics

Energy Technology Data Exchange (ETDEWEB)

NONE

2009-05-13

By 2010 there will be over 3.5 billion mobile phones subscribers, 2 billion TVs in use around the world and 1 billion personal computers. Electronic devices are a growing part of our lives and many of us can count between 20 and 30 separate items in our homes, from major items like televisions to a host of small gadgets. The communication and entertainment benefits these bring are not only going to people in wealthier nations - in Africa, for example, one in nine people now has a mobile phone. But as these electronic devices gain popularity, they account for a growing portion of household energy consumption. How 'smart' is this equipment from an energy efficiency perspective and should we be concerned about how much energy these gadgets use? What is the potential for energy savings? This new book, Gadgets and Gigawatts: Policies for Energy Efficient Electronics, includes a global assessment of the changing pattern in residential electricity consumption over the past decade and an in-depth analysis of the role played by electronic equipment. It reviews the influence that government policies have had on creating markets for more energy efficient appliances and identifies new opportunities for creating smarter, more energy efficient homes. This book is essential reading for policy makers and others interested in improving the energy efficiency of our homes.

Handling of Environmental Related Requirements : Awareness and Ability to Act at Small and Medium Sized Electric and Electronic Companies

OpenAIRE

Lin, Han-Hsuan

2008-01-01

Environmental related product requirements are increasing worldwide from government authorities, customers and other stakeholders. For small and medium sized companies manufacturing electric and electronic products it is more difficult compared to bigger companies to meet new product related requirements due to smaller budget, resources and knowledge. This research studies the awareness and ability to act upon changes when small and medium sized companies in Sweden face environmental related ...

Flow with vibrational energy exchange, application to CO2 electric laser

International Nuclear Information System (INIS)

Dahan, Claude.

1974-01-01

The performances of a continuous wave (CO 2 , N 2 , He) laser ionized by an electron beam are calculated. Several types of phenomena are considered: energy exchange processes between molecules of laser medium, electron molecular excitation processes, aerodynamic phenomena: the energy exchanges accompanying the laser effect generate important quantities of heat, which have to be evacuated by the flow. After a survey of the fundamental assumptions on molecular phenomena, a computer code was developed for following, along the flow, the evolution of the thermodynamic parameters (pressure, temperature), of the laser gain, and of the electrical properties (electron density and temperature). To provide a finer description of the last ones, a model giving the energy distribution of the electrons in the laser medium was established [fr

High Energy Electron Dosimetry by Alanine/ESR Spectroscopy

International Nuclear Information System (INIS)

Chu, Sung Sil

1989-01-01

Dosimetry based on electron spin resonance(ESR) analysis of radiation induced free radicals in amino acids is relevant to biological dosimetry applications. Alanine detectors are without walls and are tissue equivalent. Therefore, alanine ESR dosimetry looks promising for use in the therapy level. The dose range of the alanine/ESR dosimetry system can be extended down to l Gy. In a water phantom the absorbed dose of electrons generated by a medical linear accelerator of different initial energies (6-21 MeV) and therapeutic dose levels(1-60 Gy) was measured. Furthermore, depth dose measurements carried out with alanine dosimeters were compared with ionization chamber measurements. As the results, the measured absorbed doses for shallow depth of initial electron energies above 15 MeV were higher by 2-5% than those calculated by nominal energy CE factors. This seems to be caused by low energy scattered beams generated from the scattering foil and electron cones of beam projecting device in medical linear accelerator

Ultra high energy electrons powered by pulsar rotation.

Science.gov (United States)

Mahajan, Swadesh; Machabeli, George; Osmanov, Zaza; Chkheidze, Nino

2013-01-01

A new mechanism of particle acceleration, driven by the rotational slow down of the Crab pulsar, is explored. The rotation, through the time dependent centrifugal force, can efficiently excite unstable Langmuir waves in the electron-positron (hereafter e(±)) plasma of the star magnetosphere. These waves, then, Landau damp on electrons accelerating them in the process. The net transfer of energy is optimal when the wave growth and the Landau damping times are comparable and are both very short compared to the star rotation time. We show, by detailed calculations, that these are precisely the conditions for the parameters of the Crab pulsar. This highly efficient route for energy transfer allows the electrons in the primary beam to be catapulted to multiple TeV (~ 100 TeV) and even PeV energy domain. It is expected that the proposed mechanism may, unravel the puzzle of the origin of ultra high energy cosmic ray electrons.

Electron energy-distribution functions in gases

International Nuclear Information System (INIS)

Pitchford, L.C.

1981-01-01

Numerical calculation of the electron energy distribution functions in the regime of drift tube experiments is discussed. The discussion is limited to constant applied fields and values of E/N (ratio of electric field strength to neutral density) low enough that electron growth due to ionization can be neglected

Electronic pre-publishing for worldwide access

International Nuclear Information System (INIS)

Dallman, D.; Draper, M.; Schwarz, S.

1994-01-01

In High Energy Physics, as in other areas of research, paper preprints have traditionally been the primary method of communication, before publishing in a journal. Electronic bulletin boards (EBBs) are now taking over as the dominant medium. While fast and readily available EBBs do not constitute electronic journals as they bypass the referee system crucial for prestigious research journals, although this too may be achieved electronically in time. (UK)

Nonequilibrium electron energy-loss kinetics in metal clusters

CERN Document Server

Guillon, C; Fatti, N D; Vallee, F

2003-01-01

Ultrafast energy exchanges of a non-Fermi electron gas with the lattice are investigated in silver clusters with sizes ranging from 4 to 26 nm using a femtosecond pump-probe technique. The results yield evidence for a cluster-size-dependent slowing down of the short-time energy losses of the electron gas when it is strongly athermal. A constant rate is eventually reached after a few hundred femtoseconds, consistent with the electron gas internal thermalization kinetics, this behaviour reflecting evolution from an individual to a collective electron-lattice type of coupling. The timescale of this transient regime is reduced in small nanoparticles, in agreement with speeding up of the electron-electron interactions with size reduction. The experimental results are in quantitative agreement with numerical simulations of the electron kinetics.

The source of multi spectral energy of solar energetic electron

Energy Technology Data Exchange (ETDEWEB)

Herdiwijaya, Dhani [Astronomy Division and Bosscha Observatory, Faculty Mathematics and Natural Sciences, Intitute Technology of Bandung, Ganesha 10, Bandung, Indonesia 40132 dhani@as.itb.ac.id (Indonesia)

2015-04-16

We study the solar energetic electron distribution obtained from ACE and GOES satellites which have different altitudes and electron spectral energy during the year 1997 to 2011. The electron spectral energies were 0.038–0.315 MeV from EPAM instrument onboard ACE satellite and >2 MeV from GOES satellite. We found that the low electron energy has no correlation with high energy. In spite of we have corrected to the altitude differences. It implied that they originated from time dependent events with different sources and physical processes at the solar atmosphere. The sources of multi spectral energetic electron were related to flare and CME phenomena. However, we also found that high energetic electron comes from coronal hole.

Current state and prospects of industrial application of electron beam irradiation

International Nuclear Information System (INIS)

Washio, Masakazu

2000-01-01

This paper reviewed the low energy, medium energy, and high energy accelerators used for the industrial application of electron beams. Next, it described the absorption of electron beam energy, distribution of the absorbed dose of electron beams in a substance, and the basis of electron beam reaction. Furthermore, as the industrial application examples of electron beams, it briefly described about the reforming and curing of polymers, irradiation effect of inorganic material (characteristic control of semiconductors), and sterilization. Regarding curing, as examples using mainly low energy electron beams (300 keV or below), this paper briefly explained the manufacture of thermosensitive recording materials, electron beam cured silicone for release papers, tunnel metal interior finishing board, high gloss - high smooth paper. Finally, it looked at latest trends and prospects of electron beam generators. (A.O.)

Electron capture and energy-gain spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Taulbjerg, K.

1989-01-01

The applicability of translation energy spectroscopy as a tool to determine individual reaction cross sections in atomic collisions is analyzed with special emphasis on the electron capture process in highly charged ion collisions. A condition is derived to separate between higher collision energies where translation energy spectroscopy is problem free and lower energies where strong overlap of individual spectra features prohibits an analysis of the total translation energy spectrum by means of a simple deconvolution procedure. 8 refs., 6 figs.

Electron energy spectrum in core-shell elliptic quantum wire

Directory of Open Access Journals (Sweden)

V.Holovatsky

2007-01-01

Full Text Available The electron energy spectrum in core-shell elliptic quantum wire and elliptic semiconductor nanotubes are investigated within the effective mass approximation. The solution of Schrodinger equation based on the Mathieu functions is obtained in elliptic coordinates. The dependencies of the electron size quantization spectrum on the size and shape of the core-shell nanowire and nanotube are calculated. It is shown that the ellipticity of a quantum wire leads to break of degeneration of quasiparticle energy spectrum. The dependences of the energy of odd and even electron states on the ratio between semiaxes are of a nonmonotonous character. The anticrosing effects are observed at the dependencies of electron energy spectrum on the transversal size of the core-shell nanowire.

Analytic approach to auroral electron transport and energy degradation

International Nuclear Information System (INIS)

Stamnes, K.

1980-01-01

The interaction of a beam of auroral electrons with the atmosphere is described by the linear transport equation, encompassing discrete energy loss, multiple scattering, and secondary electrons. A solution to the transport equation provides the electron intensity as a function of altitude, pitch angle (with respect to the geomagnetic field) and energy. A multi-stream (discrete ordinate) approximation to the transport equation is developed. An analytic solution is obtained in this approximation. The computational scheme obtained by combining the present transport code with the energy degradation method of Swartz (1979) conserves energy identically. The theory provides a framework within which angular distributions can be easily calculated and interpreted. Thus, a detailed study of the angular distributions of 'non-absorbed' electrons (i.e., electrons that have lost just a small fraction of their incident energy) reveals a systematic variation with incident angle and energy, and with penetration depth. The present approach also gives simple yet accurate solutions in low order multi-stream approximations. The accuracy of the four-stream approximation is generally within a few per cent, whereas two-stream results for backscattered mean intensities and fluxes are accurate to within 10-15%. (author)

Low-energy electron transmission through high aspect ratio Al O nanocapillaries

DEFF Research Database (Denmark)

Milosavljević, A.R.; Jureta, J.; Víkor, G.

2009-01-01

Electron transmission through insulating AlO nanocapillaries of different diameters (40 and 270 nm) and 15 μm length has been investigated for low-energy electrons (2-120 V). The total intensity of transmitted current weakly depends on the incident electron energy and tilt angle defined with resp......Electron transmission through insulating AlO nanocapillaries of different diameters (40 and 270 nm) and 15 μm length has been investigated for low-energy electrons (2-120 V). The total intensity of transmitted current weakly depends on the incident electron energy and tilt angle defined...

LAT Perspectives in Detection of High Energy Cosmic Ray Electrons

International Nuclear Information System (INIS)

Moiseev, Alexander; Ormes, J.F.; Funk, Stefan

2007-01-01

The LAT science objectives and capabilities in the detection of high energy electrons in the energy range from 20 GeV to ∼1.5 TeV are presented. LAT simulations are used to establish the event selections. It is found that maintaining the efficiency of electron detection at the level of 30%, the residual hadron contamination does not exceed 2-3% of the electron flux. It is expected to collect ∼ ten million of electrons with the energy above 20 GeV for one year of observation. Precise spectrum reconstruction with collected electron statistics opens the unique opportunity to investigate several important problems such as models of IC radiation, revealing the signatures of nearby sources such as high energy cutoff in the electron spectrum, testing the propagation model, and search for KKDM particles decay through their contribution to the electron spectrum

Fiscal 1999 survey report on long-term energy technological strategies and the like. Long-term energy technological strategy survey (Medium-term energy technological strategy survey); 1999 nendo choki energy gijutsu senryaku nado ni kansuru chosa hokokusho. Choki energy gijutsu senryaku chosa (chuki energy gijutsu senryaku chosa)

Energy Technology Data Exchange (ETDEWEB)

NONE

2000-03-01

Energy strategies to be implemented under the New Sunshine Program by around 2010 have been compiled, with nation's industrial technological strategies, long-term energy outlook, and the like taken into consideration. The present survey aims to work out medium-term energy technological strategies. In Chapter 2, by conducting studies on the state of energy strategies in the national industry technological strategies as primarily compiled, long-term energy supply and demand outlook, and the history so far of the New Sunshine Program, and social conditions surrounding energy/environmental technologies and energy conditions are arranged in order and then analyzed with a view to deriving social needs. In Chapter 3, in view of the derived social needs, medium-term energy technological strategies are broken down into strategic target details, based on the important regions and major and minor strategic targets of the national industry technological strategies. In Chapter 4, medium-term energy technological strategies are worked out. In Chapter 5, 'basic ideas,' 'measures for promoting technology development,' 'return of the fruits to society' are mentioned as the methods of realizing the strategies. In Chapter 6, surveys and researches are summarized, and future development is predicted. (NEDO)

Medium modifications with recoil polarization

Energy Technology Data Exchange (ETDEWEB)

Brand, J.F.J. van den [Nationaal Instituut voor Kernfysica en Hoge Energiefysica, Amsterdam (Netherlands); Ent, R. [CEBAF, Newport News, VA (United States)

1994-04-01

The authors show that the virtual Compton scattering process allows for a precise study of the off-shell electron-nucleon vertex. In a separable model, they show the sensitivity to new unconstrained structure functions of the nucleon, beyond the usual Dirac and Pauli form factors. In addition, they show the sensitivity to bound nucleon form factors using the reaction 4He({rvec e},e{prime},{rvec p}){sup 3}H. A nucleon embedded in a nucleus represents a complex system. Firstly, the bound nucleon is necessarily off-shell and in principle a complete understanding of the dynamical structure of the nucleon is required in order to calculate its off-shell electromagnetic interaction. Secondly, one faces the possibility of genuine medium effects, such as for example quark-exchange contributions. Furthermore, the electromagnetic coupling to the bound nucleon is dependent on the nuclear dynamics through the self-energy of the nucleon in the nuclear medium.

Electronic Energy Transfer in Polarizable Heterogeneous Environments

DEFF Research Database (Denmark)

Svendsen, Casper Steinmann; Kongsted, Jacob

2015-01-01

such couplings provide important insight into the strength of interaction between photo-active pigments in protein-pigment complexes. Recently, attention has been payed to how the environment modifies or even controls the electronic couplings. To enable such theoretical predictions, a fully polarizable embedding......-order multipole moments. We use this extended model to systematically examine three different ways of obtaining EET couplings in a heterogeneous medium ranging from use of the exact transition density to a point-dipole approximation. Several interesting observations are made including that explicit use...... of transition densities in the calculation of the electronic couplings - also when including the explicit environment contribution - can be replaced by a much simpler transition point charge description without comprising the quality of the model predictions....

Modulation transfer function and detective quantum efficiency of electron bombarded charge coupled device detector for low energy electrons

International Nuclear Information System (INIS)

Horacek, Miroslav

2005-01-01

The use of a thinned back-side illuminated charge coupled device chip as two-dimensional sensor working in direct electron bombarded mode at optimum energy of the incident signal electrons is demonstrated and the measurements of the modulation transfer function (MTF) and detective quantum efficiency (DQE) are described. The MTF was measured for energy of electrons 4 keV using an edge projection method and a stripe projection method. The decrease of the MTF for a maximum spatial frequency of 20.8 cycles/mm, corresponding to the pixel size 24x24 μm, is 0.75≅-2.5 dB, and it is approximately the same for both horizontal and vertical directions. DQE was measured using an empty image and the mixing factor method. Empty images were acquired for energies of electrons from 2 to 5 keV and for various doses, ranging from nearly dark image to a nearly saturated one. DQE increases with increasing energy of bombarded electrons and reaches 0.92 for electron energy of 5 keV. For this energy the detector will be used for the angle- and energy-selective detection of signal electrons in the scanning low energy electron microscope

Middle-energy electron anisotropies in the auroral region

Directory of Open Access Journals (Sweden)

P. Janhunen

2004-01-01

Full Text Available Field-aligned anisotropic electron distribution functions of T_∥ > T_⊥ type are observed on auroral field lines at both low and high altitudes. We show that typically the anisotropy is limited to a certain range of energies, often below 1keV, although sometimes extending to slightly higher energies as well. Almost always there is simultaneously an isotropic electron distribution at higher energies. Often the anisotropies are up/down symmetrical, although cases with net upward or downward electron flow also occur. For a statistical analysis of the anisotropies we divide the energy range into low (below 100eV, middle (100eV–1keV and high (above 1keV energies and develop a measure of anisotropy expressed in density units. The statistical magnetic local time and invariant latitude distribution of the middle-energy anisotropies obeys that of the average auroral oval, whereas the distributions of the low and high energy anisotropies are more irregular. This suggests that it is specifically the middle-energy anisotropies that have something to do with auroral processes. The anisotropy magnitude decreases monotonically with altitude, as one would expect, because electrons have high mobility along the magnetic field and thus, the anisotropy properties spread rapidly to different altitudes.

Key words. Magnetospheric physics (auroral phenomena. Space plasma physics (wave-particle interactions; changed particle motion and acceleration

Optimization of power output and study of electron beam energy spread in a Free Electron Laser oscillator

CERN Document Server

Abramovich, A; Efimov, S; Gover, A; Pinhasi, Y; Yahalom, A

2001-01-01

Design of a multi-stage depressed collector for efficient operation of a Free Electron Laser (FEL) oscillator requires knowledge of the electron beam energy distribution. This knowledge is necessary to determine the voltages of the depressed collector electrodes that optimize the collection efficiency and overall energy conversion efficiency of the FEL. The energy spread in the electron beam is due to interaction in the wiggler region, as electrons enter the interaction region at different phases relative to the EM wave. This interaction can be simulated well by a three-dimensional simulation code such as FEL3D. The main adjustable parameters that determine the electron beam energy spread after interaction are the e-beam current, the initial beam energy, and the quality factor of the resonator out-coupling coefficient. Using FEL3D, we study the influence of these parameters on the available radiation power and on the electron beam energy distribution at the undulator exit. Simulations performed for I=1.5 A, E...

Very low energy scanning electron microscopy in nanotechnology

Czech Academy of Sciences Publication Activity Database

Müllerová, Ilona; Hovorka, Miloš; Mika, Filip; Mikmeková, Eliška; Mikmeková, Šárka; Pokorná, Zuzana; Frank, Luděk

2012-01-01

Roč. 9, 8/9 (2012), s. 695-716 ISSN 1475-7435 R&D Projects: GA MŠk OE08012; GA MŠk ED0017/01/01; GA AV ČR IAA100650902 Institutional research plan: CEZ:AV0Z20650511 Keywords : scanning electron microscopy * very low energy electrons * cathode lens * grain contrast * strain contrast * imaging of participates * dopant contrast * very low energy STEM * graphene Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.087, year: 2012

Central Arkansas Energy Project. Coal to medium-Btu gas

Science.gov (United States)

1982-05-01

The Central Arkansas Energy Project has as its objective the conversion of coal in a central location to a more readily usable energy source, medium Btu gas (MBG), for use at dispersed locations as fuel for power production and steam generation, or as a feedstock for chemical processing. The project elements consist of a gasification facility to produce MBG from coal, a pipeline to supply the MBG to the dispersed sites. The end of line users investigated were the repowering or refueling of an existing Arkansas Power and Light Co. Generating station, an ammonia plant, and a combined cycle cogeneration facility for the production of steam and electricity. Preliminary design of the gasification plant including process engineering design bases, process flow diagrams, utility requirements, system description, project engineering design, equipment specifications, plot plan and section plot plans, preliminary piping and instrument diagrams, and facilities requirements. Financial analyses and sensitivities are determined. Design and construction schedules and manpower loadings are developed. It is concluded that the project is technically feasible, but the financial soundness is difficult to project due to uncertainty in energy markets of competing fuels.

Fast electrons in small solar flares

International Nuclear Information System (INIS)

Lin, R.P.

1975-01-01

Because approximately 5-100 keV electrons are frequently accelerated and emitted by the Sun in small flares, it is possible to define a detailed characteristic physical picture of these events. The review summarizes both the direct spacecraft observations of non-relativistic solar electrons, and observations of the X-ray and radio emission generated by these particles at the Sun and in the interplanetary medium. These observations bear on the basic astrophysical process of particle acceleration in tenuous plasmas. It is found that in many small solar flares the approximately 5-100 keV electrons accelerated during flash phase constitute the bulk of the total flare energy. Thus the basic flare mechanism in these flares essentially converts the available flare energy into fast electrons. These electrons may produce the other flare electromagnetic emissions through their interactions with the solar atmosphere. In large proton flares these electrons may provide the energy to eject material from the Sun and to create a shock wave which could then accelerate nuclei and electrons to much higher energies. (Auth.)

Dose specification for radiation therapy: dose to water or dose to medium?

International Nuclear Information System (INIS)

Ma, C-M; Li Jinsheng

2011-01-01

The Monte Carlo method enables accurate dose calculation for radiation therapy treatment planning and has been implemented in some commercial treatment planning systems. Unlike conventional dose calculation algorithms that provide patient dose information in terms of dose to water with variable electron density, the Monte Carlo method calculates the energy deposition in different media and expresses dose to a medium. This paper discusses the differences in dose calculated using water with different electron densities and that calculated for different biological media and the clinical issues on dose specification including dose prescription and plan evaluation using dose to water and dose to medium. We will demonstrate that conventional photon dose calculation algorithms compute doses similar to those simulated by Monte Carlo using water with different electron densities, which are close (<4% differences) to doses to media but significantly different (up to 11%) from doses to water converted from doses to media following American Association of Physicists in Medicine (AAPM) Task Group 105 recommendations. Our results suggest that for consistency with previous radiation therapy experience Monte Carlo photon algorithms report dose to medium for radiotherapy dose prescription, treatment plan evaluation and treatment outcome analysis.

Design, development and characterization of tetrode type electron gun system for generation of low energy electrons

International Nuclear Information System (INIS)

Deore, A.V.; Bhoraskar, V.N.; Dhole, S.D.

2011-01-01

A tetrode type electron gun system for the generation of low energy electrons was designed, developed and characterized. An electron gun having four electrodes namely cathode, focusing electrode, control electrode and anode has been designed for the irradiation experiments. This electron gun is capable to provide electrons of energy over the range of 1 keV to 20 keV, with current maximum upto 100 μA. The electron gun and a faraday cup are mounted in the evacuated cylindrical chamber. The samples are fixed on the faraday cup and irradiated with low energy electrons at a pressure around 10 -6 mbar. In this electron gun system, at any electron energy over the entire range, the electron beam diameter can be varied from 5 to 120 mm on the Faraday cup mounted at a distance of 200 mm from the anode in the chamber. Also, the circular shape of the beam spot was maintained, even though the beam current and beam diameter are varied. The uniformity of the electron beam over the entire beam area was measured with a multi electrode assembly and found to be well within 15%. This system is being used for the synthesis and diffusion of metal and semiconductor nanoparticles in polymeric materials. (author)

Hot-electron-based solar energy conversion with metal-semiconductor nanodiodes

Science.gov (United States)

Lee, Young Keun; Lee, Hyosun; Lee, Changhwan; Hwang, Euyheon; Park, Jeong Young

2016-06-01

Energy dissipation at metal surfaces or interfaces between a metal and a dielectric generally results from elementary excitations, including phonons and electronic excitation, once external energy is deposited to the surface/interface during exothermic chemical processes or an electromagnetic wave incident. In this paper, we outline recent research activities to develop energy conversion devices based on hot electrons. We found that photon energy can be directly converted to hot electrons and that hot electrons flow through the interface of metal-semiconductor nanodiodes where a Schottky barrier is formed and the energy barrier is much lower than the work function of the metal. The detection of hot electron flow can be successfully measured using the photocurrent; we measured the photoyield of photoemission with incident photons-to-current conversion efficiency (IPCE). We also show that surface plasmons (i.e. the collective oscillation of conduction band electrons induced by interaction with an electromagnetic field) are excited on a rough metal surface and subsequently decay into secondary electrons, which gives rise to enhancement of the IPCE. Furthermore, the unique optical behavior of surface plasmons can be coupled with dye molecules, suggesting the possibility for producing additional channels for hot electron generation.

Absorbed dose determination in water in medium energy x-ray beam

International Nuclear Information System (INIS)

Nisevic, G.; Spasic-Jokic, V.

1998-01-01

Absorbed dose determination in water phantom in medium energy X-ray beam, according to IAEA recommendations is given. This method is applied on Radiotherapy department of Military Academy Hospital in Belgrade. Reference points of measurements are on depth of 5 cm and 2 cm as it recommended in ref. Experimental results are shown in aim to introduce new dosimetric concept based on air kerma calibration factor recommended for application in our radiotherapy centers (author)

Microanalysis by spectroscopy of transmitted electron energy losses

International Nuclear Information System (INIS)

Colliex, C.; Trebbia, P.

1978-01-01

Among the various signals which, in a transmission electron microscope, result from the interactions between the primary beam of well defined energy E 0 and the sample, the spectrum of the energy distribution of the electrons transmitted contains useful informations on the chemical and physical properties of the sample. Consequently the adaptation of an energy dispersive system on an electron microscope enables new fields of research to be investigated, particularly a localised chemical analysis technique with a space resolution scale equal to that of the electron microscope. It is this second aspect that we suggest describing in particular here. Already, this technique appears to be indispensable in the problems arising from the analysis of very small quantities of matter: detection limits in the order of 10 -19 to 10 -20 g (around 100 to 1000 atoms) would seem to be resonably possible [fr

Electronic properties of Mn-phthalocyanine–C60 bulk heterojunctions: Combining photoemission and electron energy-loss spectroscopy

International Nuclear Information System (INIS)

Roth, Friedrich; Herzig, Melanie; Knupfer, Martin; Lupulescu, Cosmin; Darlatt, Erik; Gottwald, Alexander; Eberhardt, Wolfgang

2015-01-01

The electronic properties of co-evaporated mixtures (blends) of manganese phthalocyanine and the fullerene C 60 (MnPc:C 60 ) have been studied as a function of the concentration of the two constituents using two supplementary electron spectroscopic methods, photoemission spectroscopy (PES) and electron energy-loss spectroscopy (EELS) in transmission. Our PES measurements provide a detailed picture of the electronic structure measured with different excitation energies as well as different mixing ratios between MnPc and C 60 . Besides a relative energy shift, the occupied electronic states of the two materials remain essentially unchanged. The observed energy level alignment is different compared to that of the related CuPc:C 60 bulk heterojunction. Moreover, the results from our EELS investigations show that, despite the rather small interface interaction, the MnPc related electronic excitation spectrum changes significantly by admixing C 60 to MnPc thin films

Electron polarimetry at low energies in Hall C at JLab

International Nuclear Information System (INIS)

Gaskell, D.

2013-01-01

Although the majority of Jefferson Lab experiments require multi-GeV electron beams, there have been a few opportunities to make electron beam polarization measurements at rather low energies. This proceedings will discuss some of the practical difficulties encountered in performing electron polarimetry via Mo/ller scattering at energies on the order of a few hundred MeV. Prospects for Compton polarimetry at very low energies will also be discussed. While Mo/ller scattering is likely the preferred method for electron polarimetry at energies below 500 MeV, there are certain aspects of the polarimeter and experiment design that must be carefully considered

CuInGaSe{sub 2} nanoparticles by pulsed laser ablation in liquid medium

Energy Technology Data Exchange (ETDEWEB)

Mendivil, M.I.; García, L.V. [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, San Nicolás de los Garza, Nuevo León, 66455 (Mexico); Krishnan, B. [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, San Nicolás de los Garza, Nuevo León, 66455 (Mexico); CIIDIT—Universidad Autónoma de Nuevo León, Apodaca, Nuevo León (Mexico); Avellaneda, D. [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, San Nicolás de los Garza, Nuevo León, 66455 (Mexico); and others

2015-12-15

Highlights: • CIGS nanocolloids were synthesized using PLAL technique. • Characterized their morphology, structure, composition and optical properties. • Morphologies were dependent on ablation wavelength and liquid medium. • Optical absorption and bandgap of these nanocolloids were tunable. - Abstract: Pulsed laser ablation in liquid medium (PLALM) is a nanofabrication technique to produce complex nanostructures. CuInGaSe{sub 2} (CIGS) is an alloy with applications in photovoltaic industry. In this work, we studied the effects of laser ablation wavelength, energy fluence and liquid medium on the properties of the CIGS nanoparticles synthesized by PLALM. The nanoparticles obtained were analyzed by transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), selected area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS) and UV–vis absorption spectroscopy. XPS results confirmed the chemical states and composition of the ablated products. TEM analysis showed different morphologies for the nanomaterials obtained in different liquid media and ablation wavelengths. The optical properties for these CIGS nanocolloids were analyzed using UV–vis absorption spectroscopy. The results demonstrated the use of PLALM as a useful synthesis technique for nanoparticles of quaternary photovoltaic materials.

Recent results in the development of a global medium-energy nucleon-nucleus optical-model potential

International Nuclear Information System (INIS)

Madland, D.G.

1988-02-01

Initial results are presented for the determination of a global medium-energy nucleon-nucleus phenomenological optical-model potential using a relativistic Schroedinger representation. The starting point for this work is the global phenomenological optical-model potential of Schwandt /ital et al./, which is based on measured elastic scattering cross sections and analyzing power for polarized protons ranging from 80 to 180 MeV. This potential is optimally modified to reproduce experimental proton reaction cross sections as a function of energy, while allowing only minimal deterioration in the fits to the elastic cross sections and analyzing powers. Further modifications in the absorptive potential were found necessary to extrapolate the modified potential to higher energies. The final potential is converted to a neutron-nucleus potential by use of standard Lane model assumptions and by accounting approximately for the Coulomb correction. Comparisons of measured and calculated proton reaction and neutron total cross sections are presented for 27 Al, 56 Fe, and 208 Pb. Medium-energy optical-model potentials for complex projectiles are briefly discussed in an appendix. 7 refs., 20 figs

Applications of Electronstatic Lenses to Electron Gun and Energy Analyzers

International Nuclear Information System (INIS)

Sise, O.

2004-01-01

Focal properties and geometries are given for several types of electrostatic lens systems commonly needed in electron impact studies. One type is an electron gun which focuses electrons over a wide range of energy onto a fixed point, such as target, and the other type is an analyzer system which focuses scattered electrons of variable energy onto a fixed position, such as the entrance plane of an analyzer. There are many different types and geometries of these lenses for controlling and focusing of the electron beams. In this presentation we discussed the criteria used for the design of the electrostatic lenses associated with the electron gun and energy analyzers and determined the fundamental relationships between the operation and behaviour of multi-element electrostatic lenses, containing five, six and seven elements. The focusing of the electron beam was achieved by applying suitable voltages to the series of these lens elements, Design of the lens system for electron gun was based on our requirements that the beam at the target had a small spot size and zero beam angle, that is, afocal mode. For energy analyzer systems we considered the entrance of the hemispherical analyzer which determines the energy of the electron beam and discussed the focusing condition of this lens systems

Probing medium-induced jet splitting and energy loss in heavy-ion collisions

Science.gov (United States)

Chang, Ning-Bo; Cao, Shanshan; Qin, Guang-You

2018-06-01

The nuclear modification of jet splitting in relativistic heavy-ion collisions at RHIC and the LHC energies is studied based on the higher twist formalism. Assuming coherent energy loss for the two splitted subjets, a non-monotonic jet energy dependence is found for the nuclear modification of jet splitting function: strongest modification at intermediate jet energies whereas weaker modification for larger or smaller jet energies. Combined with the smaller size and lower density of the QGP medium at RHIC than at the LHC, this helps to understand the groomed jet measurements from CMS and STAR Collaborations: strong modification of the momentum sharing zg distribution at the LHC and no obvious modification of zg distribution at RHIC. In addition, the observed nuclear modification pattern of the groomed jet zg distribution cannot be explained solely by independent energy loss of the two subjets. Our result may be tested in future measurements of groomed jets with lower jet energies at the LHC and larger jet energies at RHIC, for different angular separations between the two subjets.

X-ray diffraction study of stress relaxation in cubic boron nitride films grown with simultaneous medium-energy ion bombardment

International Nuclear Information System (INIS)

Abendroth, B.; Gago, R.; Eichhorn, F.; Moeller, W.

2004-01-01

Relaxation of the intrinsic stress of cubic boron nitride (cBN) thin films has been studied by x-ray diffraction (XRD) using synchrotron light. The stress relaxation has been attained by simultaneous medium-energy ion bombardment (2-10 keV) during magnetron sputter deposition, and was confirmed macroscopically by substrate curvature measurements. In order to investigate the stress-release mechanisms, XRD measurements were performed in in-plane and out-of-plane geometry. The analysis shows a pronounced biaxial state of compressive stress in the cBN films grown without medium-energy ion bombardment. This stress is partially released during the medium-energy ion bombardment. It is suggested that the main path for stress relaxation is the elimination of strain within the cBN grains due to annealing of interstitials

Degradation of vitamin C by low-energy electrons

Science.gov (United States)

Abdoul-Carime, Hassan; Illenberger, Eugen

2004-06-01

We report on the degradation of gas phase vitamin C (ascorbic acid, AA) induced by low-energy electrons. In the energy range of (0-12) eV, different negatively charged fragments, attributed to the dehydro-ascorbic acid anion ((AA-H) -), OH -, O - and H -, are observed. The yield functions indicate that these ions are formed via dissociative electron attachment, DEA. While the formation of (AA-H) - is exclusively observed at sub-excitation energies (<1.5 eV), the other fragments arise from resonance features at higher energies. Possible implications of these observations for radiation damage and food treatment by high energy radiation are considered.

Co-generation and innovative heat storage systems in small-medium CSP plants for distributed energy production

Science.gov (United States)

Giaconia, Alberto; Montagnino, Fabio; Paredes, Filippo; Donato, Filippo; Caputo, Giampaolo; Mazzei, Domenico

2017-06-01

CSP technologies can be applied for distributed energy production, on small-medium plants (on the 1 MW scale), to satisfy the needs of local communities, buildings and districts. In this perspective, reliable, low-cost, and flexible small/medium multi-generative CSP plants should be developed. Four pilot plants have been built in four Mediterranean countries (Cyprus, Egypt, Jordan, and Italy) to demonstrate the approach. In this paper, the plant built in Italy is presented, with specific innovations applied in the linear Fresnel collector design and the Thermal Energy Storage (TES) system, based on a single the use of molten salts but specifically tailored for small scale plants.

Chiral magnetic currents with QGP medium response in heavy-ion collisions at RHIC and LHC energies

Science.gov (United States)

She, Duan; Feng, Sheng-Qin; Zhong, Yang; Yin, Zhong-Bao

2018-03-01

We calculate the electromagnetic current with a more realistic approach in the RHIC and LHC energy regions in the article. We take the partons formation time as the initial time of the magnetic field response of QGP medium. The maximum electromagnetic current and the time-integrated current are two important characteristics of the chiral magnetic effect (CME), which can characterize the intensity and duration of fluctuations of CME. We consider the finite frequency response of CME to a time-varying magnetic field, find a significant impact from QGP medium feedback, and estimate the generated electromagnetic current as a function of time, beam energy and impact parameter.

Monte Carlo electron-transport calculations for clinical beams using energy grouping

Energy Technology Data Exchange (ETDEWEB)

Teng, S P; Anderson, D W; Lindstrom, D G

1986-01-01

A Monte Carlo program has been utilized to study the penetration of broad electron beams into a water phantom. The MORSE-E code, originally developed for neutron and photon transport, was chosen for adaptation to electrons because of its versatility. The electron energy degradation model employed logarithmic spacing of electron energy groups and included effects of elastic scattering, inelastic-moderate-energy-loss-processes and inelastic-large-energy-loss-processes (catastrophic). Energy straggling and angular deflections were modeled from group to group, using the Moeller cross section for energy loss, and Goudsmit-Saunderson theory to describe angular deflections. The resulting energy- and electron-deposition distributions in depth were obtained at 10 and 20 MeV and are compared with ETRAN results and broad beam experimental data from clinical accelerators.

Variation of kinetic energy release with temperature and electron energy for unimolecular ionic transitions

International Nuclear Information System (INIS)

Rabia, M.A.; Fahmy, M.A.

1992-01-01

The kinetic energy released during seven unimolecular ionic transitions, generated from benzyl alcohol and benzyl amine have been studied as a function of ion source temperature and ionizing electron energy. Only, the kinetic energy released during H CN elimination from fragment [C 7 H 8 N]+ ion of benzyl amine displays a temperature dependence. For only two transitions, generated from benzyl alcohol, the kinetic energy released show a significant ionizing electron energy dependence. These results may reveal the role of the internal energy of reacting ions in producing the kinetic energy released some transitions produced from benzyl alcohol

Elastic scattering of low-energy electrons from ammonia

International Nuclear Information System (INIS)

Alle, D.T.; Gulley, R.J.; Buckman, S.J.; Brunger, M.J.

1992-01-01

We report absolute differential cross section measurements for vibrationally elastic electron scattering from NH 3 at incident energies from 2-30 eV. The present results, from a crossed electron-molecular beam apparatus, represent the first comprehensive experimental attempt to quantify the elastic electron-NH 3 scattering process. At each energy studied we have integrated our differential cross section data to generate total elastic and elastic momentum transfer cross sections and a critical comparison of both our differential and integral cross sections against previous experiment and theory is provided. We also report our observation of a strong Feshbach resonance in the elastic channel at an energy of 5.59 ± 0.05 eV. (Author)

Scattering of polarized low-energy electrons by ferromagnetic metals

International Nuclear Information System (INIS)

Helman, J.S.

1981-01-01

A source of spin polarized electrons with remarkable characteristics based on negative electron affinity (NEA) GaAs has recently been developed. It constitutes a unique tool to investigate spin dependent interactions in electron scattering processes. The characteristics and working principles of the source are briefly described. Some theoretical aspects of the scattering of polarized low-energy electrons by ferromagnetic metals are discussed. Finally, the results of the first polarized low-energy electron diffraction experiment using the NEA GaAs source are reviewed; they give information about the surface magnetization of ferromagnetic Ni (110). (Author) [pt

Energy-weighted dynamical scattering simulations of electron diffraction modalities in the scanning electron microscope.

Science.gov (United States)

Pascal, Elena; Singh, Saransh; Callahan, Patrick G; Hourahine, Ben; Trager-Cowan, Carol; Graef, Marc De

2018-04-01

Transmission Kikuchi diffraction (TKD) has been gaining momentum as a high resolution alternative to electron back-scattered diffraction (EBSD), adding to the existing electron diffraction modalities in the scanning electron microscope (SEM). The image simulation of any of these measurement techniques requires an energy dependent diffraction model for which, in turn, knowledge of electron energies and diffraction distances distributions is required. We identify the sample-detector geometry and the effect of inelastic events on the diffracting electron beam as the important factors to be considered when predicting these distributions. However, tractable models taking into account inelastic scattering explicitly are lacking. In this study, we expand the Monte Carlo (MC) energy-weighting dynamical simulations models used for EBSD [1] and ECP [2] to the TKD case. We show that the foil thickness in TKD can be used as a means of energy filtering and compare band sharpness in the different modalities. The current model is shown to correctly predict TKD patterns and, through the dictionary indexing approach, to produce higher quality indexed TKD maps than conventional Hough transform approach, especially close to grain boundaries. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Dose characteristics of high-energy electrons, muons and photons

International Nuclear Information System (INIS)

Britvich, G.I.; Krupnyj, G.I.; Peleshko, V.N.; Rastsvetalov, Ya.N.

1980-01-01

Differential distribution of energy release at different depth of tissue-equivalent phantoms (plexiglas, polystyrene, polyethylene) at the energy of incident electrons, muons of 0.2-40 GeV and photons with the mean energy of 3.6 GeV are measured. The error of experimental results does not exceed 7%. On the basis of the data obtained dose characteristics of electrons, muons and photons for standard geometry are estimated. For all types of irradiation the maximum value of specific equivalent dose, nremxcm 2 /part. is presented. It is shown that published values of specific equivalent dose of electron radiation are higher in all the investigated energy range from 0.2 to 40 GeV, and for muon radiation a good agreement with the present experiment is observed. The highly precise results obtained which cover the wide dynamic range according to the energy of incident particles can serve as the basis for reconsidering the existing recommendations for dose characteristics of electron radiation [ru

The measurement of the total electron content applied to the observation of medium scale gravity wave

International Nuclear Information System (INIS)

Bertel, L.; Bertin, F.; Testud, J.

1976-01-01

The interpretation of the measurements of the integrated electron content in terms of gravity wave requires (1) a gravity wave model at thermospheric altitudes; (2) a gravity wave-ionization interaction model in the F-region of the ionosphere; and (3) a computing program for the resulting perturbation on the integrated electron content between the satellite and the earth station used. The gravity wave model considered in this paper takes into account the dissipative effects (viscosity, thermal conduction) which become very importanr above 250 km altitude and the effect of the base wind which is capable of affecting deeply the propagation of the waves of medium scale. Starting with this model, the domains of frequencies and the wavelength of atmospheric waves which may exist in the upper atmosphere are considered. The interaction of such waves and the ionization is examined. The theoretical results give information particularly on the selectivity of the ionospheric response to the wave passage. The deduced selectivity of the models appears to be smaller than that given by other authors who used simplified gravity wave models. The method for computing the perturbation of the of the integrated electron content introduced by the wave passage is given for a geostationary satellite. Computational results are presented for application to the case of medium scale gravity waves. (author)

Electronic energy transfer through non-adiabatic vibrational-electronic resonance. II. 1D spectra for a dimer

Science.gov (United States)

Tiwari, Vivek; Jonas, David M.

2018-02-01

Vibrational-electronic resonance in photosynthetic pigment-protein complexes invalidates Förster's adiabatic framework for interpreting spectra and energy transfer, thus complicating determination of how the surrounding protein affects pigment properties. This paper considers the combined effects of vibrational-electronic resonance and inhomogeneous variations in the electronic excitation energies of pigments at different sites on absorption, emission, circular dichroism, and hole-burning spectra for a non-degenerate homodimer. The non-degenerate homodimer has identical pigments in different sites that generate differences in electronic energies, with parameters loosely based on bacteriochlorophyll a pigments in the Fenna-Matthews-Olson antenna protein. To explain the intensity borrowing, the excited state vibrational-electronic eigenvectors are discussed in terms of the vibrational basis localized on the individual pigments, as well as the correlated/anti-correlated vibrational basis delocalized over both pigments. Compared to those in the isolated pigment, vibrational satellites for the correlated vibration have the same frequency and precisely a factor of 2 intensity reduction through vibrational delocalization in both absorption and emission. Vibrational satellites for anti-correlated vibrations have their relaxed emission intensity reduced by over a factor 2 through vibrational and excitonic delocalization. In absorption, anti-correlated vibrational satellites borrow excitonic intensity but can be broadened away by the combination of vibronic resonance and site inhomogeneity; in parallel, their vibronically resonant excitonic partners are also broadened away. These considerations are consistent with photosynthetic antenna hole-burning spectra, where sharp vibrational and excitonic satellites are absent. Vibrational-excitonic resonance barely alters the inhomogeneously broadened linear absorption, emission, and circular dichroism spectra from those for a

Optimization of power output and study of electron beam energy spread in a Free Electron Laser oscillator

International Nuclear Information System (INIS)

Abramovich, A.; Pinhasi, Y.; Yahalom, A.; Bar-Lev, D.; Efimov, S.; Gover, A.

2001-01-01

Design of a multi-stage depressed collector for efficient operation of a Free Electron Laser (FEL) oscillator requires knowledge of the electron beam energy distribution. This knowledge is necessary to determine the voltages of the depressed collector electrodes that optimize the collection efficiency and overall energy conversion efficiency of the FEL. The energy spread in the electron beam is due to interaction in the wiggler region, as electrons enter the interaction region at different phases relative to the EM wave. This interaction can be simulated well by a three-dimensional simulation code such as FEL3D. The main adjustable parameters that determine the electron beam energy spread after interaction are the e-beam current, the initial beam energy, and the quality factor of the resonator out-coupling coefficient. Using FEL3D, we study the influence of these parameters on the available radiation power and on the electron beam energy distribution at the undulator exit. Simulations performed for I=1.5 A, E=1.4 MeV, L=20% (Internal loss factor) showed that the highest radiated output power and smallest energy spread are attained for an output coupler transmission coefficient T m congruent with 30%

Feasibility of a medium-size central cogenerated energy facility, energy management memorandum

Science.gov (United States)

Porter, R. W.

1982-09-01

The thermal-economic feasibility was studied of a medium-size central cogenerated energy facility designed to serve five varied industries. Generation options included one dual-fuel diesel and one gas turbine, both with waste heat boilers, and five fired boilers. Fuels included natural gas, and for the fired-boiler cases, also low-sulphur coal and municipal refuse. The fired-boiler cogeneration systems employed back-pressure steam turbines. For coal and refuse, the option of steam only without cogeneration was also assessed. The refuse-fired cases utilized modular incinerators. The options provided for a wide range of steam and electrical capacities. Deficient steam was assumed generated independently in existing equipment. Excess electrical power over that which could be displaced was assumed sold to Commonwealth Edison Company under PURPA (Public Utility Regulator Policies Act). The facility was assumed operated by a mutually owned corporation formed by the cogenerated power users. The economic analysis was predicted on currently applicable energy-investment tax credits and accelerated depreciation for a January 1985 startup date. Based on 100% equity financing, the results indicated that the best alternative was the modular-incinerator cogeneration system.

Electron, photons, and molecules: Storing energy from light

Energy Technology Data Exchange (ETDEWEB)

Miller, J.R. [Argonne National Laboratory, IL (United States)

1996-09-01

Molecular charge separation has important potential for photochemical energy storage. Its efficiency can be enhanced by principals which maximize the rates of the electron transfer steps which separate charge and minimize those which recombine high-energy charge pairs to lose stored energy. Dramatic scientific progress in understanding these principals has occurred since the founding of DOE and its predecessor agency ERDA. While additional knowledge in needed in broad areas of molecular electron transfer, some key areas of knowledge hold particular promise for the possibility of moving this area from science toward technology capable of contributing to the nation`s energy economy.

Medium energy hadron-nucleus scattering in the 1/N expansion formalism

International Nuclear Information System (INIS)

Kuyucak, S.; Morrison, I.

1992-01-01

The algebraic-eikonal approach to the medium energy hadron-nucleus scattering is generalized to arbitrary interactions and boson types using the 1/N expansion technique for the interacting boson model. The results are used in a comparative study of proton scattering from deformed nuclei in the sd and sdg boson models. The two models give almost identical results for a pure quadrupole interaction but widely differ when a hexadecapole interaction is included. 25 refs., 3 tabs., 7 figs

Study and realization of an electron gun at low energy

International Nuclear Information System (INIS)

Camus, P.

1977-01-01

This work presents the theoretical concepts and experimental design of an electron gun. This gun is working in the weak energy range and the focus position is independant of electron energy measurements and analysis methods of the electron beam are described [fr

Imaging properties and energy aberrations of a double-pass cylindrical-mirror electron energy analyzer

International Nuclear Information System (INIS)

Erickson, N.E.; Powell, C.J.

1986-01-01

The imaging properties and energy aberrations of a commercial double-pass cylindrical-mirror analyzer have been characterized using an extension of the method recently reported by Seah and Mathieu. The electron beam from the coaxial electron gun was rastered across a test surface and the intensity of either elastically scattered electrons or of electrons at other selected energies was stored in a computer as a function of beam position on the specimen and other experimental parameters. The intensity data were later plotted to provide an ''image'' of the detected intensity. Images of this type are presented for electron energies of 100, 500, and 1000 eV and for the application of small offset voltages (typically between -1 and +5 V) between the analyzer and the gun cathode with the instrument operated in conditions appropriate for XPS or AES. Small offset voltages ( or approx. =5 V) lead to image shapes similar to those for the elastic peak but with 20%--40% increased widths. Deflection of the incident beam by up to 2 mm from the axis caused variations of up to +-0.15 eV in the measured positions of the elastic peak. Our observations can be interpreted qualitatively in terms of the known relationship between detected signal and combinations of position of electron emission from the specimen, angle of emission, and electron energy. The images obtained with elastically and inelastically scattered electrons provide a convenient and quantitative means of assessing instrument performance and of defining the specimen area being analyzed for the particular combination of instrument operating conditions and the energy width of AES or XPS features from the specimen

Damage of DNA by Low Energy Electrons (< 3 eV)

International Nuclear Information System (INIS)

Bald, Ilko; Illenberger, Eugen; Kopyra, Janina

2012-01-01

Recent experiments on low energy electron attachment to DNA and its components in the condensed phase and in the gas phase are reviewed and analysed. From different condensed phase experiments the sensitivity of DNA towards low energy electrons is well documented and strand breaks in DNA are observed at subexcitation energies (< 3 eV) and also in ultrafast electron transfer experiments involving electrons in presolvated states. Gas phase experiments indicate that all building blocks of DNA (the nucleobases, the sugar and the phosphate moiety) undergo resonant dissociative electron attachment (DEA) in the subexcitation regime which may ultimately lead to strand breaks. From very recent gas phase experiments on an entire nucleotide it can be concluded that most strand breaks result from direct electron attachment to the DNA backbone, but also initial electron capture by the nucleobase following electron transfer to the backbone contributes.

Experimental parameters for quantitative surface analysis by medium energy ion scattering, ch. 1

International Nuclear Information System (INIS)

Turkenburg, W.C.; Kersten, H.H.; Colenbrander, B.G.; Jongh, A.P. de; Saris, F.W.

1976-01-01

A new UHV chamber for surface and surface layer analysis by collision spectroscopy of backscattered ions at medium energies is described. Experimental parameters like energy, angular and depth resolution, crystal alignment and background pressure are discussed. Formulae based on the use of an electrostatic energy analyser show that the analysis can be quantitative. Effects of beam induced build-up of a hydro-carbon layer, sputter cleaning and creation of radiation damage have been investigated for Cu (110) and Ni (110). Detection sensitivity for Carbon, Oxygen and Sulfur on Cu and Ni has been found to be 0.2, 0.1 and 0.03 of a monolayer respectively

Dose controlled low energy electron irradiator for biomolecular films.

Science.gov (United States)

Kumar, S V K; Tare, Satej T; Upalekar, Yogesh V; Tsering, Thupten

2016-03-01

We have developed a multi target, Low Energy Electron (LEE), precise dose controlled irradiator for biomolecular films. Up to seven samples can be irradiated one after another at any preset electron energy and dose under UHV conditions without venting the chamber. In addition, one more sample goes through all the steps except irradiation, which can be used as control for comparison with the irradiated samples. All the samples are protected against stray electron irradiation by biasing them at -20 V during the entire period, except during irradiation. Ethernet based communication electronics hardware, LEE beam control electronics and computer interface were developed in house. The user Graphical User Interface to control the irradiation and dose measurement was developed using National Instruments Lab Windows CVI. The working and reliability of the dose controlled irradiator has been fully tested over the electron energy range of 0.5 to 500 eV by studying LEE induced single strand breaks to ΦX174 RF1 dsDNA.

Dose controlled low energy electron irradiator for biomolecular films

Energy Technology Data Exchange (ETDEWEB)

Kumar, S. V. K., E-mail: svkk@tifr.res.in; Tare, Satej T.; Upalekar, Yogesh V.; Tsering, Thupten [Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005 (India)

2016-03-15

We have developed a multi target, Low Energy Electron (LEE), precise dose controlled irradiator for biomolecular films. Up to seven samples can be irradiated one after another at any preset electron energy and dose under UHV conditions without venting the chamber. In addition, one more sample goes through all the steps except irradiation, which can be used as control for comparison with the irradiated samples. All the samples are protected against stray electron irradiation by biasing them at −20 V during the entire period, except during irradiation. Ethernet based communication electronics hardware, LEE beam control electronics and computer interface were developed in house. The user Graphical User Interface to control the irradiation and dose measurement was developed using National Instruments Lab Windows CVI. The working and reliability of the dose controlled irradiator has been fully tested over the electron energy range of 0.5 to 500 eV by studying LEE induced single strand breaks to ΦX174 RF1 dsDNA.

Estimation of the characteristic energy of electron precipitation

Directory of Open Access Journals (Sweden)

C. F. del Pozo

2002-09-01

Full Text Available Data from simultaneous observations (on 13 February 1996, 9 November 1998, and 12 February 1999 with the IRIS, DASI and EISCAT systems are employed in the study of the energy distribution of the electron precipitation during substorm activity. The estimation of the characteristic energy of the electron precipitation over the common field of view of IRIS and DASI is discussed. In particular, we look closely at the physical basis of the correspondence between the characteristic energy, the flux-averaged energy, as defined below, and the logarithm of the ratio of the green-light intensity to the square of absorption. This study expands and corrects results presented in the paper by Kosch et al. (2001. It is noticed, moreover, that acceleration associated with diffusion processes in the magnetosphere long before precipitation may be controlling the shape of the energy spectrum. We propose and test a "mixed" distribution for the energy-flux spectrum, exponential at the lower energies and Maxwellian or modified power-law at the higher energies, with a threshold energy separating these two regimes. The energy-flux spectrum at Tromsø, in the 1–320 keV range, is derived from EISCAT electron density profiles in the 70–140 km altitude range and is applied in the "calibration" of the optical intensity and absorption distributions, in order to extrapolate the flux and characteristic energy maps.Key words. Ionosphere (auroral ionosphere; particle precipitation; particle acceleration

Estimation of the characteristic energy of electron precipitation

Directory of Open Access Journals (Sweden)

C. F. del Pozo

Full Text Available Data from simultaneous observations (on 13 February 1996, 9 November 1998, and 12 February 1999 with the IRIS, DASI and EISCAT systems are employed in the study of the energy distribution of the electron precipitation during substorm activity. The estimation of the characteristic energy of the electron precipitation over the common field of view of IRIS and DASI is discussed. In particular, we look closely at the physical basis of the correspondence between the characteristic energy, the flux-averaged energy, as defined below, and the logarithm of the ratio of the green-light intensity to the square of absorption. This study expands and corrects results presented in the paper by Kosch et al. (2001. It is noticed, moreover, that acceleration associated with diffusion processes in the magnetosphere long before precipitation may be controlling the shape of the energy spectrum. We propose and test a "mixed" distribution for the energy-flux spectrum, exponential at the lower energies and Maxwellian or modified power-law at the higher energies, with a threshold energy separating these two regimes. The energy-flux spectrum at Tromsø, in the 1–320 keV range, is derived from EISCAT electron density profiles in the 70–140 km altitude range and is applied in the "calibration" of the optical intensity and absorption distributions, in order to extrapolate the flux and characteristic energy maps.

Key words. Ionosphere (auroral ionosphere; particle precipitation; particle acceleration

New method of ionization energy calculation for two-electron ions

International Nuclear Information System (INIS)

Ershov, D.K.

1997-01-01

A new method for calculation of the ionization energy of two-electron ions is proposed. The method is based on the calculation of the energy of second electron interaction with the field of an one-electron ion the potential of which is well known

Diffraction of high energy electrons

International Nuclear Information System (INIS)

Bourret, A.

1981-10-01

The diffraction of electrons by a crystal is examined to study its structure. As the electron-substance interaction is strong, it must be treated in a dynamic manner. Using the N waves theory and physical optics the base equations giving the wave at the outlet are deduced for a perfect crystal and their equivalence is shown. The more complex case of an imperfect crystal is then envisaged in these two approaches. In both cases, only the diffraction of high energy electrons ( > 50 KeV) are considered since in the diffraction of slow electrons back scattering cannot be ignored. Taking into account an increasingly greater number of beams, through fast calculations computer techniques, enables images to be simulated in very varied conditions. The general use of the Fast Fourier Transform has given a clear cut practical advantage to the multi-layer method [fr

Trends in Power Electronics and Control of Renewable Energy Systems

DEFF Research Database (Denmark)

Blaabjerg, Frede; Iov, Florin; Kerekes, Tamas

2010-01-01

term) based energy sources to renewable energy sources. Another is to use high efficient power electronics in power generation, power transmission/distribution and end-user application. This paper discuss trends of the most emerging renewable energy sources, wind energy and photovoltaics, which...... by means of power electronics are changing the future electrical infrastructure but also contributes steadily more to non-carbon based electricity production. Most focus is on the power electronics technologies used. In the case of photovoltaics transformer-less systems are discussed as they have...

Energy and temperature fluctuations in the single electron box

International Nuclear Information System (INIS)

Berg, Tineke L van den; Brange, Fredrik; Samuelsson, Peter

2015-01-01

In mesoscopic and nanoscale systems at low temperatures, charge carriers are typically not in thermal equilibrium with the surrounding lattice. The resulting, non-equilibrium dynamics of electrons has only begun to be explored. Experimentally the time-dependence of the electron temperature (deviating from the lattice temperature) has been investigated in small metallic islands. Motivated by these experiments, we investigate theoretically the electronic energy and temperature fluctuations in a metallic island in the Coulomb blockade regime, tunnel coupled to an electronic reservoir, i.e. a single electron box. We show that electronic quantum tunnelling between the island and the reservoir, in the absence of any net charge or energy transport, induces fluctuations of the island electron temperature. The full distribution of the energy transfer as well as the island temperature is derived within the framework of full counting statistics. In particular, the low-frequency temperature fluctuations are analysed, fully accounting for charging effects and non-zero reservoir temperature. The experimental requirements for measuring the predicted temperature fluctuations are discussed. (paper)

Examples from P2 and energy assessments at small to medium size manufacturers

International Nuclear Information System (INIS)

Fleischman, M.; Watters, J.C.; Cobourn, W.G.; Collins, D.J.

1996-01-01

Using engineering student-faculty teams, the U.S. Department of energy sponsored industrial assessment center (IAC) at the university of louisville does free pollution prevention and energy assessments at small to medium size manufacturers (SIC 20-39) in kentucky and indiana. Each client plant must meet three of the following four criteria: Annual energy bills less than $1, 750, 000 and more than $50, 00. Gross annual sales of less than $75 million. Less than 500 employees. Lack a dedicated energy/waste engineer. Lack of in-house staff to perform these analyses. The program criteria and assessment procedures are briefly described and summaries of assessment at a sheet fed offset (lithographic) printing plant and 2 denim jeans pre washing plants are presented. 4 figs., 8 tabs

Electron energy-loss spectrometry at the frontier of spatial and energy resolution

International Nuclear Information System (INIS)

Hofer, F.; Grogger, W.; Kothleitner, G.

2004-01-01

Full text: Electron energy-loss spectroscopy (EELS) in the transmission electron microscope (TEM) is now used routinely as a means of measuring chemical and structural properties of very small regions of a thin specimen. The power of this technique depends significantly on two parameters: its spatial resolution and the energy resolution available in the spectrum and in the energy-filtered TEM (EFTEM) image. The cold field emission source and the Schottky emitter have made an energy resolution below 1 eV possible and it is now feasible to obtain data with a spatial resolution close to atomic dimensions, given the right instrumentation and specimen. EFTEM allows to record elemental maps at sub-nanometre resolution, being mainly limited by chromatic and spherical aberration of the objective lens and by delocalization of inelastic scattering. Recently the possibility of correcting spherical and even chromatic aberrations of electron lenses has become a practical reality thus improving the point resolution of the TEM to below 0.1 nm. The other limiting factor for EFTEM resolution is delocalization. However, recent measurements show that resolution values in the range of 1 nm and below can be achieved, even for energy-losses of only a few eV. In terms of energy-resolution, EELS and EFTEM compare less favourably with other spectroscopies. For common TEMs, the overall energy-resolution is mainly determined by the energy width of the electron source, typically between 0.5 and 1.5 eV. For comparison, synchrotron x-ray sources and beam line spectrometers, provide a resolution well below 0.1 eV for absorption spectroscopy. During the early sixties, the energy spread of an electron beam could be reduced by incorporating an energy-filter into the illumination system, but the system lacked spatial resolution. Later developments combined high energy resolution in the range of 0.1 eV with improved spatial resolution. Recently, FEI introduced a new high resolution EELS system based

Evolutionary developments in x ray and electron energy loss microanalysis instrumentation for the analytical electron microscope

Science.gov (United States)

Zaluzec, Nester J.

Developments in instrumentation for both X ray Dispersive and Electron Energy Loss Spectroscopy (XEDS/EELS) over the last ten years have given the experimentalist a greatly enhanced set of analytical tools for characterization. Microanalysts have waited for nearly two decades now in the hope of getting a true analytical microscope and the development of 300 to 400 kV instruments should have allowed us to attain this goal. Unfortunately, this has not generally been the case. While there have been some major improvements in the techniques, there has also been some devolution in the modern AEM (Analytical Electron Microscope). In XEDS, the majority of today's instruments are still plagued by the hole count effect, which was first described in detail over fifteen years ago. The magnitude of this problem can still reach the 20 percent level for medium atomic number species in a conventional off-the-shelf intermediate voltage AEM. This is an absurd situation and the manufacturers should be severely criticized. Part of the blame, however, also rests on the AEM community for not having come up with a universally agreed upon standard test procedure. Fortunately, such a test procedure is in the early stages of refinement. The proposed test specimen consists of an evaporated Cr film approx. 500 to 1000A thick supported upon a 3mm diameter Molybdenum 200 micron aperture.

Reactions induced by low energy electrons in cryogenic films

International Nuclear Information System (INIS)

Bass, A.D.; Sanche, L.

2003-01-01

We review recent research on reactions (including dissociation) initiated by low-energy electron bombardment of monolayer and multilayer molecular solids at cryogenic temperatures. With incident electrons of energies below 20 eV, dissociation is observed by the electron stimulated desorption (ESD) of anions from target films and is attributed to the processes of dissociative electron attachment (DEA) and to dipolar dissociation. It is shown that DEA to condensed molecules is sensitive to environmental factors such as the identity of co-adsorbed species and film morphology. The effects of image-charge induced polarization on cross-sections for DEA to CH3Cl are also discussed. Taking as examples, the electron-induced production of CO within multilayer films of methanol and acetone, it is shown that the detection of electronic excited states by high resolution electron energy loss spectroscopy can be used to monitor electron beam damage. In particular, the incident energy dependence of the CO indicates that below 19 eV, dissociation proceeds via the decay of transient negative ions (TNI) into electronically excited dissociative states. The electron induced dissociation of biomolecular targets is also considered, taking as examples the ribose analog tetrahydrofuran and DNA bases adenine and thymine, cytosine and guanine. The ESD of anions from such films also show dissociation via the formation of TNI. In multilayer molecular solids, fragment species resulting from dissociation, may react with neighboring molecules, as is demonstrated in anion ESD measurements from films containing O 2 and various hydrocarbon molecules. X-ray photoelectron spectroscopy measurements reported for electron irradiated monolayers of H 2 O and CF 4 on a Si - H passivated surface further show that DEA is an important initial step in the electron-induced chemisorption of fragment species

Thermalisation of high energy electrons and positrons in water vapour

Science.gov (United States)

Munoz, A.; Blanco, F.; Limao-Vieira, P.; Thorn, P. A.; Brunger, M. J.; Buckman, S. J.; Garcia, G.

2008-07-01

In this study we describe a method to simulate single electron tracks of electrons in molecular gases, particularly in water vapour, from relatively high energies, where Born (Inokuti 1971) approximation is supposed to be valid, down to thermal energies paying special attention to the low energy secondary electrons which are abundantly generated along the energy degradation procedure. Experimental electron scattering cross sections (Munoz et al. 2007) and energy loss spectra (Thorn et al. 2007) have been determined, where possible, to be used as input parameters of the simulating program. These experimental data have been complemented with optical potential calculation (Blanco and Garcia 2003) providing a complete set of interaction probability functions for each type of collision which could take place in the considered energy range: elastic, ionization, electronic excitation, vibrational and rotational excitation. From the simulated track structure (Munoz et al. 2005) information about energy deposition and radiation damage at the molecular level can be derived. A similar procedure is proposed to the study of single positron tracks in gases. Due to the lack of experimental data for positron interaction with molecules, especially for those related to energy loss and excitation cross sections, some distribution probability data have been derived from those of electron scattering by introducing positron characteristics as positroniun formation. Preliminary results for argon are presented discussing also the utility of the model to biomedical applications based on positron emitters.

Low Energy Electrons in the Mars Plasma Environment

Science.gov (United States)

Link, Richard

2001-01-01

The ionosphere of Mars is rather poorly understood. The only direct measurements were performed by the Viking 1 and 2 landers in 1976, both of which carried a Retarding Potential Analyzer. The RPA was designed to measure ion properties during the descent, although electron fluxes were estimated from changes in the ion currents. Using these derived low-energy electron fluxes, Mantas and Hanson studied the photoelectron and the solar wind electron interactions with the atmosphere and ionosphere of Mars. Unanswered questions remain regarding the origin of the low-energy electron fluxes in the vicinity of the Mars plasma boundary. Crider, in an analysis of Mars Global Surveyor Magnetometer/Electron Reflectometer measurements, has attributed the formation of the magnetic pile-up boundary to electron impact ionization of exospheric neutral species by solar wind electrons. However, the role of photoelectrons escaping from the lower ionosphere was not determined. In the proposed work, we will examine the role of solar wind and ionospheric photoelectrons in producing ionization in the upper ionosphere of Mars. Low-energy (internal (photoelectron) sources of ionization, and accounts for Auger electron production. The code will be used to analyze Mars Global Surveyor measurements of solar wind and photoelectrons down to altitudes below 200 km in the Mars ionosphere, in order to determine the relative roles of solar wind and escaping photoelectrons in maintaining plasma densities in the region of the Mars plasma boundary.

Detection of X-ray fluorescence of light elements by electron counting in a low-pressure gaseous electron multiplier

International Nuclear Information System (INIS)

Pansky, A.; Breskin, A.; Chechik, R.; Malamud, G.

1992-12-01

Ionization electrons deposited by soft X-rays in a low pressure (10 Torr) gas medium are efficiently counted by a multistage electron multiplier, providing an accurate measurement of the X-ray photon energy. Energy resolution of 56-28% FWHM were measured for X-rays of 110-676 eV, recording electrical induced charges or visible photons emitted during the avalanche process. It is demonstrated that a combined analysis of the number of electron trail length of an event, provides a powerful and competitive way of resolving ultra soft X-rays. We present the experimental technique, discuss the advantages and limitations of the Primary Electron Counter, and suggest ways to improve its performances. (authors)

Power electronics - key technology for renewable energy systems

DEFF Research Database (Denmark)

Blaabjerg, Frede; Iov, Florin; Kerekes, Tamas

2011-01-01

sources to renewable energy sources. Another is to use high efficient power electronics in power generation, power transmission/distribution and end-user application. This paper discuss trends of the most emerging renewable energy sources, wind energy and photovoltaics, which by means of power electronics...... as efficient as possible. Further, the emerging climate changes is arguing to find sustainable future solutions. Of many options, two major technologies will play important roles to solve parts of those future problems. One is to change the electrical power production from conventional, fossil based energy......The electrical energy consumption continues to grow and more applications are based on electricity. We can expect that more 60% of all energy consumption will be converted and used as electricity. Therefore, it is a demand that production, distribution and use of electrical energy are done...

Modeling the high-energy electronic state manifold of adenine: Calibration for nonlinear electronic spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Nenov, Artur, E-mail: Artur.Nenov@unibo.it; Giussani, Angelo; Segarra-Martí, Javier; Jaiswal, Vishal K. [Dipartimento di Chimica “G. Ciamician,” Università di Bologna, Via Selmi 2, IT-40126 Bologna (Italy); Rivalta, Ivan [Université de Lyon, CNRS, Institut de Chimie de Lyon, École Normale Supérieure de Lyon, 46 Allée d’Italie, F-69364 Lyon Cedex 07 (France); Cerullo, Giulio [Dipartimento di Fisica, Politecnico di Milano, IFN-CNR, Piazza Leonardo Da Vinci 32, IT-20133 Milano (Italy); Mukamel, Shaul [Department of Chemistry, University of California, Irvine, California 92697-2025 (United States); Garavelli, Marco, E-mail: marco.garavelli@unibo.it, E-mail: marco.garavelli@ens-lyon.fr [Dipartimento di Chimica “G. Ciamician,” Università di Bologna, Via Selmi 2, IT-40126 Bologna (Italy); Université de Lyon, CNRS, Institut de Chimie de Lyon, École Normale Supérieure de Lyon, 46 Allée d’Italie, F-69364 Lyon Cedex 07 (France)

2015-06-07

Pump-probe electronic spectroscopy using femtosecond laser pulses has evolved into a standard tool for tracking ultrafast excited state dynamics. Its two-dimensional (2D) counterpart is becoming an increasingly available and promising technique for resolving many of the limitations of pump-probe caused by spectral congestion. The ability to simulate pump-probe and 2D spectra from ab initio computations would allow one to link mechanistic observables like molecular motions and the making/breaking of chemical bonds to experimental observables like excited state lifetimes and quantum yields. From a theoretical standpoint, the characterization of the electronic transitions in the visible (Vis)/ultraviolet (UV), which are excited via the interaction of a molecular system with the incoming pump/probe pulses, translates into the determination of a computationally challenging number of excited states (going over 100) even for small/medium sized systems. A protocol is therefore required to evaluate the fluctuations of spectral properties like transition energies and dipole moments as a function of the computational parameters and to estimate the effect of these fluctuations on the transient spectral appearance. In the present contribution such a protocol is presented within the framework of complete and restricted active space self-consistent field theory and its second-order perturbation theory extensions. The electronic excited states of adenine have been carefully characterized through a previously presented computational recipe [Nenov et al., Comput. Theor. Chem. 1040–1041, 295-303 (2014)]. A wise reduction of the level of theory has then been performed in order to obtain a computationally less demanding approach that is still able to reproduce the characteristic features of the reference data. Foreseeing the potentiality of 2D electronic spectroscopy to track polynucleotide ground and excited state dynamics, and in particular its expected ability to provide

Golden mean energy equals highest atomic electron orbital energy

Energy Technology Data Exchange (ETDEWEB)

Malinowski, Leonard J. [Interdisciplinary Research Club, P.O. Box 371, Monroeville, PA 15146 (United States)], E-mail: LJMalinowski@gmail.com

2009-12-15

The golden mean numerical value {phi} = 0.5({radical}5 - 1) has been given a physical manifestation through E infinity theory. This short paper relates the golden mean energy 0.618034 MeV to atomic electron orbitals.

Golden mean energy equals highest atomic electron orbital energy

International Nuclear Information System (INIS)

Malinowski, Leonard J.

2009-01-01

The golden mean numerical value φ = 0.5(√5 - 1) has been given a physical manifestation through E infinity theory. This short paper relates the golden mean energy 0.618034 MeV to atomic electron orbitals.

Dual Energy CT Angiography of Peripheral Arterial Disease: Feasibility of Using Lower Contrast Medium Volume.

Directory of Open Access Journals (Sweden)

Abdulrahman Almutairi

Full Text Available One of the main drawbacks associated with Dual Energy Computed Tomography Angiography (DECTA is the risk of developing contrast medium-induced nephropathy (CIN. The aim of the present study was firstly, to design an optimal CT imaging protocol by determining the feasibility of using a reduced contrast medium volume in peripheral arterial DECTA, and secondly, to compare the results with those obtained from using routine contrast medium volume.Thirty four patients underwent DECTA for the diagnosis of peripheral arterial disease. They were randomly divided into two groups: Group 1 (routine contrast volume group with n = 17, injection rate 4-5 ml/s, and 1.5 ml/kg of contrast medium, and Group 2 ((low contrast volume group, with n = 17, injection rate 4-5ml/s, and contrast medium volume 0.75 ml/kg. A fast kilovoltage-switching 64-slice CT scanner in the dual-energy mode was employed for the study. A total of 6 datasets of monochromatic images at 50, 55, 60, 65, 70 and 75 keV levels were reconstructed with adaptive statistical iterative reconstruction (ASIR at 50%. A 4-point scale was the tool for qualitative analysis of results. The two groups were compared and assessed quantitatively for image quality on the basis of signal-to-noise ratio (SNR and contrast-to-noise-ratio (CNR. Radiation and contrast medium doses were also compared.The overall mean CT attenuation and mean noise for all lower extremity body parts was significantly lower for the low volume contrast group (p<0.001, and varied significantly between groups (p = 0.001, body parts (p<0.001 and keVs (p<0.001. The interaction between group body parts was significant with CT attenuation and CNR (p = 0.002 and 0.003 respectively, and marginally significant with SNR (p = 0.047, with minimal changes noticed between the two groups. Group 2 (low contrast volume group displayed the lowest image noise between 65 and 70 keV, recorded the highest SNR and CNR at 65 keV, and produced significantly lower

Electron heating and energy inventory during asymmetric reconnection in a laboratory plasma

Science.gov (United States)

Yoo, J.; Na, B.; Jara-Almonte, J.; Yamada, M.; Ji, H.; Roytershteyn, V.; Argall, M. R.; Fox, W.; Chen, L. J.

2017-12-01

Electron heating and the energy inventory during asymmetric reconnection are studied in the Magnetic Reconnection Experiment (MRX) [1]. In this plasma, the density ratio is about 8 across the current sheet. Typical features of asymmetric reconnection such as the large density gradients near the low-density-side separatrices, asymmetric in-plane electric field, and bipolar out-of-plane magnetic field are observed. Unlike the symmetric case [2], electrons are also heated near the low-density-side separatrices. The measured parallel electric field may explain the observed electron heating. Although large fluctuations driven by lower-hybrid drift instabilities are also observed near the low-density-side separatrices, laboratory measurements and numerical simulations reported here suggest that they do not play a major role in electron energization. The average electron temperature increase in the exhaust region is proportional to the incoming magnetic energy per an electron/ion pair but exceeds the scaling of the previous space observations [3]. This discrepancy is explained by differences in the boundary condition and system size. The profile of electron energy gain from the electric field shows that there is additional electron energy gain associated with the electron diamagnetic current besides a large energy gain near the X-line. This additional energy gain increases electron enthalpy, not the electron temperature. Finally, a quantitative analysis of the energy inventory during asymmetric reconnection is conducted. Unlike the symmetric case where the ion energy gain is about twice more than the electron energy gain [4], electrons and ions obtain a similar amount of energy during asymmetric reconnection. [1] J. Yoo et al., accepted for a publication in J. Geophys. Res. [2] J. Yoo et al., Phys. Plasmas 21, 055706 (2014). [3] T. Phan et al., Geophys. Res. Lett. 40, 4475 (2013). [4] M. Yamada et al., Nat. Comms. 5, 4474 (2014).

Strong interactions studies with medium energy probes

International Nuclear Information System (INIS)

Seth, K.K.

1993-10-01

This progress report refers to the period August 1992 to August 1993, which includes the first year of the three-year period December 1, 1992--November 30, 1995 of the existing research contract. As anticipated in the 1992--1995 proposal the major preoccupation during 1992--1993 was with Fermilab experiment E760. This experiment, whose primary objective is to make very high-resolution study of Charmonium Spectroscopy via proton-antiproton annihilations, has turned out to be a veritable gold-mine of exciting hadronic physics in other areas as well. These include the proton from factor in the time-life region, proton-antiproton forward scattering, QCD scaling laws, and light quark spectroscopy. A large fraction of the data from E760 have been analyzed during this year, and several papers have been published. In addition to the E760 experiment at Fermilab continued progress was made earlier nuclear physics-related experiments at LAMPF, MIT, and NIKHEF, and their results for publication. Topics include high- resolution electron scattering, quasi-free electron scattering and low-energy pion double charge exchange

Formation of a superhigh energy electron spectrum in the Galaxy

International Nuclear Information System (INIS)

Agaronyan, F.A.; Ambartsumyan, A.S.

1985-01-01

The formation of superhigh energy electron spectrum in the disk of the galaxy and halo is considered. A different behaviour of the electron spectrum within the framework of capture models in disk or halo, in the energy region E> or approximately 10 5 GeV is revealed due to the account of relativistic corrections ir the energy losses of electrons during the inverse Compton scattering. A comparison with the existing experimental data is carried out

Low Energy Electron Cooler for NICA Booster

CERN Document Server

Denisov, A P

2017-01-01

BINP has developed an electron cooler to increase the ion accumulation efficiency in the NICA (Nuclotron-based Ion Collider fAcility) heavy ion booster (JINR, Dubna). Adjustment of the cooler magnetic system provides highly homogeneous magnetic field in the cooling section B trans/B long ≤ 4∙10-5 which is vital for efficient electron cooling. First experiments with an electron beam performed at BINP demonstrated the target DC current of 500 mA and electron energy 6 keV.

Secondary Electrons as an Energy Source for Life

Science.gov (United States)

Stelmach, Kamil B.; Neveu, Marc; Vick-Majors, Trista J.; Mickol, Rebecca L.; Chou, Luoth; Webster, Kevin D.; Tilley, Matt; Zacchei, Federica; Escudero, Cristina; Flores Martinez, Claudio L.; Labrado, Amanda; Fernández, Enrique J. G.

2018-01-01

Life on Earth is found in a wide range of environments as long as the basic requirements of a liquid solvent, a nutrient source, and free energy are met. Previous hypotheses have speculated how extraterrestrial microbial life may function, among them that particle radiation might power living cells indirectly through radiolytic products. On Earth, so-called electrophilic organisms can harness electron flow from an extracellular cathode to build biomolecules. Here, we describe two hypothetical mechanisms, termed "direct electrophy" and "indirect electrophy" or "fluorosynthesis," by which organisms could harness extracellular free electrons to synthesize organic matter, thus expanding the ensemble of potential habitats in which extraterrestrial organisms might be found in the Solar System and beyond. The first mechanism involves the direct flow of secondary electrons from particle radiation to a microbial cell to power the organism. The second involves the indirect utilization of impinging secondary electrons and a fluorescing molecule, either biotic or abiotic in origin, to drive photosynthesis. Both mechanisms involve the attenuation of an incoming particle's energy to create low-energy secondary electrons. The validity of the hypotheses is assessed through simple calculations showing the biomass density attainable from the energy supplied. Also discussed are potential survival strategies that could be used by organisms living in possible habitats with a plentiful supply of secondary electrons, such as near the surface of an icy moon. While we acknowledge that the only definitive test for the hypothesis is to collect specimens, we also describe experiments or terrestrial observations that could support or nullify the hypotheses.

Electronic structure and correlated wave functions of a few electron quantum dots

Energy Technology Data Exchange (ETDEWEB)

Sako, Tokuei [Laboratory of Physics, College of Science and Technology, Nihon University, 7-24-1 Narashinodai, Funabashi, Chiba 274-8501 (Japan); Ishida, Hiroshi [College of Humanities and Sciences, Nihon University, Tokyo 156-8550 (Japan); Fujikawa, Kazuo [Institute of Quantum Science, College of Science and Technology, Nihon University, Chiyoda-ku, Tokyo 101-8308 (Japan)

2015-01-22

The energy spectra and wave functions of a few electrons confined by a quasi-one-dimensional harmonic and anharmonic potentials have been studied by using a full configuration interaction method employing a Cartesian anisotropic Gaussian basis set. The energy spectra are classified into three regimes of the strength of confinement, namely, large, medium and small. The polyad quantum number defined by a total number of nodes in the wave functions is shown to be a key ingredient to interpret the energy spectra for the whole range of the confinement strength. The nodal pattern of the wave functions exhibits normal modes for the harmonic confining potential, indicating collective motions of electrons. These normal modes are shown to undergo a transition to local modes for an anharmonic potential with large anharmonicity.

Electron-atom scattering at intermediate energies

International Nuclear Information System (INIS)

Kingston, A.E.; Walters, H.R.J.

1982-01-01

The problems of intermediate energy scattering are approached from the low and high energy ends. At low intermediate energies difficulties associated with the use of pseudostates and correlation terms are discussed, special consideration being given to nonphysical pseudoresonances. Perturbation methods appropriate to high intermediate energies are described and attempts to extend these high energy approximations down to low intermediate energies are studied. It is shown how the importance of electron exchange effects develops with decreasing energy. The problem of assessing the 'effective completeness' of pseudostate sets at intermediate energies is mentioned and an instructive analysis of a 2p pseudostate approximation to elastic e - -H scattering is given. It is suggested that at low energies the Pauli Exclusion Principle can act to hide short range defects in pseudostate approximations. (author)

Correction factors for the NMi free-air ionization chamber for medium-energy x-rays calculated with the Monte Carlo method

International Nuclear Information System (INIS)

Grimbergen, T.W.M.; Dijk, E. van; Vries, W. de

1998-01-01

A new method is described for the determination of x-ray quality dependent correction factors for free-air ionization chambers. The method is based on weighting correction factors for mono-energetic photons, which are calculated using the Monte Carlo method, with measured air kerma spectra. With this method, correction factors for electron loss, scatter inside the chamber and transmission through the diaphragm and front wall have been calculated for the NMi free-air chamber for medium-energy x-rays for a wide range of x-ray qualities in use at NMi. The newly obtained correction factors were compared with the values in use at present, which are based on interpolation of experimental data for a specific set of x-ray qualities. For x-ray qualities which are similar to this specific set, the agreement between the correction factors determined with the new method and those based on the experimental data is better than 0.1%, except for heavily filtered x-rays generated at 250 kV. For x-ray qualities dissimilar to the specific set, differences up to 0.4% exist, which can be explained by uncertainties in the interpolation procedure of the experimental data. Since the new method does not depend on experimental data for a specific set of x-ray qualities, the new method allows for a more flexible use of the free-air chamber as a primary standard for air kerma for any x-ray quality in the medium-energy x-ray range. (author)

Ionization with accelerated high energy electrons as quarantine treatment against Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) in citrus fruits

International Nuclear Information System (INIS)

Alonso, M.; Río, M.A. del; Jacas, J.

2002-01-01

Ceratitis capitata is a quarantine pest. Spanish citrus exports to countries such as the USA or Japan are subjected to a mandatory quarantine treatment consisting of exposure of fruits to a low temperatures. Some citrus (''Fino'' lemon, ''Fortune'' mandarin) are very sensitive to this kind of treatment and can not be treated this way. Therefore, alternative treatments are necessary. In this study, high energy electrons were investigated as an alternative quarantine treatment against C. capitata in citrus. Survival of the different instars (egg to old pupae) of C. capitata reared in an artificial medium was assessed when exposed to different doses between 0 and 1 kGy. Both pupariation and adult emergence were almost prevented at 0.25 kGy, and no viable adults were obtained at 0.50 kGy. When artificially infested fruits (in both ''Fino'' lemon and ''Fortune'' mandarin) were exposed to 1 kGy, 100% mortality was obtained. Finally, quality (texture, color index, maturity index, juice yield, ethanol and acetaldehyde contents, physiological alterations and organoleptic characteristics) of irradiated (1 kGy) and non irradiated fruit were compared. High energy electron irradiation resulted in unacceptable damage to ''Fortune'' mandarin, but quality of ''Fino'' lemon resulted unaltered even when evaluated one month after irradiation. Therefore high energy electrons could be a useful alternative to cold quarantine treatment for ''Fino'' lemons. (author) [es

Advanced medium-voltage bidirectional dc-dc conversion systems for future electric energy delivery and management systems

Science.gov (United States)

Fan, Haifeng

2011-12-01

The distributed renewable energy generation and utilization are constantly growing, and are expected to be integrated with the conventional grid. The growing pressure for innovative solutions will demand power electronics to take an even larger role in future electric energy delivery and management systems, since power electronics are required for the conversion and control of electric energy by most dispersed generation systems Furthermore, power electronics systems can provide additional intelligent energy management, grid stability and power quality capabilities. Medium-voltage isolated dc-dc converter will become one of the key interfaces for grid components with moderate power ratings. To address the demand of medium voltage (MV) and high power capability for future electric energy delivery and management systems, the power electronics community and industry have been reacting in two different ways: developing semiconductor technology or directly connecting devices in series/parallel to reach higher nominal voltages and currents while maintaining conventional converter topologies; and by developing new converter topologies with traditional semiconductor technology, known as multilevel converters or modular converters. The modular approach uses the well-known, mature, and cheaper power semiconductor devices by adopting new converter topologies. The main advantages of the modular approach include: significant improvement in reliability by introducing desired level of redundancy; standardization of components leading to reduction in manufacturing cost and time; power systems can be easily reconfigured to support varying input-output specifications; and possibly higher efficiency and power density of the overall system. Input-series output-parallel (ISOP) modular configuration is a good choice to realize MV to low voltage (LV) conversion for utility application. However, challenges still remain. First of all, for the high-frequency MV utility application, the low

Electron transfer in organic glass. Distance and energy dependence

International Nuclear Information System (INIS)

Krongauz, V.V.

1992-01-01

The authors have investigated the distance and energy dependence of electron transfer in rigid organic glasses containing randomly dispersed electron donor and electron acceptor molecules. Pulsed radiolysis by an electron beam from a linear accelerator was used for ionization resulting in charge deposition on donor molecules. The disappearance kinetics of donor radical anions due to electron transfer to acceptor was monitored spectroscopically by the change in optical density at the wavelength corresponding to that of donor radical anion absorbance. It was found that the rate of the electron transfer observed experimentally was higher than that computed using the Marcus-Levich theory assuming that the electron-transfer activation barrier is equal to the binding energy of electron on the donor molecule. This discrepancy between the experimental and computed results suggests that the open-quotes inertclose quotes media in which electron-transfer reaction takes place may be participating in the process, resulting in experimentally observed higher electron-transfer rates. 32 refs., 3 figs., 2 tabs

Electron energy loss spectroscopy of gold nanoparticles on graphene

International Nuclear Information System (INIS)

DeJarnette, Drew; Roper, D. Keith

2014-01-01

Plasmon excitation decay by absorption, scattering, and hot electron transfer has been distinguished from effects induced by incident photons for gold nanoparticles on graphene monolayer using electron energy loss spectroscopy (EELS). Gold nano-ellipses were evaporated onto lithographed graphene, which was transferred onto a silicon nitride transmission electron microscopy grid. Plasmon decay from lithographed nanoparticles measured with EELS was compared in the absence and presence of the graphene monolayer. Measured decay values compared favorably with estimated radiative and non-radiative contributions to decay in the absence of graphene. Graphene significantly enhanced low-energy plasmon decay, increasing mode width 38%, but did not affect higher energy plasmon or dark mode decay. This decay beyond expected radiative and non-radiative mechanisms was attributed to hot electron transfer, and had quantum efficiency of 20%, consistent with previous reports

Deconvolution of overlapping features in electron energy-loss spectra: the determination of absolute differential cross sections for electron-impact excitation of electronic states of molecules

International Nuclear Information System (INIS)

Campbell, L.; Brunger, M.J.; Teubner, O.J.P.; Mojarrabi, B.

1996-06-01

A set of three computer programs is reported which allow for the deconvolution of overlapping molecular electronic state structure in electron energy-loss spectra, even in highly perturbed systems. This procedure enables extraction of absolute differential cross sections for electron-impact excitation of electronic states of diatomic molecules from electron energy-loss spectra. The first code in the sequence uses the Rydberg-Klein-Rees procedure to generate potential energy curves from spectroscopic constants, while the second calculates Franck-Condon factors by numerical solution of the Schroedinger equation, given the potential energy curves. The third, given these Franck-Condon factors, the previously calculated relevant energies for the vibrational levels of the respective electronic states and the experimental energy-loss spectra, extracts the differential cross sections for each state. Each program can be run independently, or the three can run in sequence to determine these cross sections from the spectroscopic constants and the experimental energy-loss spectra. The application of these programs to the specific case of electron scattering from nitric oxide (NO) is demonstrated. 25 refs., 2 tabs., 2 figs

Target electron collision effects on energy loss straggling of protons in an electron gas at any degeneracy

International Nuclear Information System (INIS)

Barriga-Carrasco, Manuel D.

2008-01-01

The purpose of the present paper is to describe the effects of target electron collisions on proton energy loss straggling in plasmas at any degeneracy. Targets are considered fully ionized so electronic energy loss is only due to the free electrons. The analysis is focused on targets with electronic density around solid values n e ≅10 23 cm -3 and with temperature around T≅10 eV; these targets are in the limit of weakly coupled electron gases. These types of plasma targets have not been studied extensively, though they are very important for inertial confinement fusion. The energy loss straggling is obtained from an exact quantum-mechanical evaluation, which takes into account the degeneracy of the target plasma, and later it is compared with common classical and degenerate approximations. Then electron collisions in the exact quantum-mechanical straggling calculation are considered. Now the energy loss straggling is enhanced for energies smaller than the energy before the maximum, then decreases around this maximum, and finally tends to the same values with respect to noncollisional calculation. Differences with the same results but not taking into account these collisions are as far as 17% in the cases analyzed. As an example, proton range distributions have been calculated to show the importance of an accurate energy straggling calculation

Energy spectrum of Compton scattering of laser photons on relativistic electrons

International Nuclear Information System (INIS)

Ando, Hiroaki; Yoneda, Yasuharu

1976-01-01

The high energy photons in gamma-ray region are obtainable by the Compton scattering of laser photons on relativistic electrons. But the motion of the electrons in the storage ring is not necessarily uniform. In the study of the uneven effect, the energy distribution of scattered photons is derived from the assumed momentum distribution of incident electrons. It is generally impossible to derive the momentum distribution of incident electrons from the energy spectrum of scattered photons. The additional conditions which make this possible in a special case are considered. A calculational method is examined for deriving the energy spectrum of scattered photons from the assumed momentum distribution of incident electrons. (Mori, K.)

Technical Support Document: Development of the Advanced Energy Design Guide for Medium to Big Box Retail Buildings - 50% Energy Savings

Energy Technology Data Exchange (ETDEWEB)

Bonnema, Eric [National Renewable Energy Lab. (NREL), Golden, CO (United States); Leach, Matt [National Renewable Energy Lab. (NREL), Golden, CO (United States); Pless, Shanti [National Renewable Energy Lab. (NREL), Golden, CO (United States)

2013-06-05

This Technical Support Document describes the process and methodology for the development of the Advanced Energy Design Guide for Medium to Big Box Retail Buildings: Achieving 50% Energy Savings Toward a Net Zero Energy Building (AEDG-MBBR) ASHRAE et al. (2011b). The AEDG-MBBR is intended to provide recommendations for achieving 50% whole-building energy savings in retail stores over levels achieved by following ANSI/ASHRAE/IESNA Standard 90.1-2004, Energy Standard for Buildings Except Low-Rise Residential Buildings (Standard 90.1-2004) (ASHRAE 2004b). The AEDG-MBBR was developed in collaboration with the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), the American Institute of Architects (AIA), the Illuminating Engineering Society of North America (IES), the U.S. Green Building Council (USGBC), and the U.S. Department of Energy.

Technical Support Document: Development of the Advanced Energy Design Guide for Medium to Big Box Retail Buildings - 50% Energy Savings

Energy Technology Data Exchange (ETDEWEB)

Bonnema, E.; Leach, M.; Pless, S.

2013-06-01

This Technical Support Document describes the process and methodology for the development of the Advanced Energy Design Guide for Medium to Big Box Retail Buildings: Achieving 50% Energy Savings Toward a Net Zero Energy Building (AEDG-MBBR) ASHRAE et al. (2011b). The AEDG-MBBR is intended to provide recommendations for achieving 50% whole-building energy savings in retail stores over levels achieved by following ANSI/ASHRAE/IESNA Standard 90.1-2004, Energy Standard for Buildings Except Low-Rise Residential Buildings (Standard 90.1-2004) (ASHRAE 2004b). The AEDG-MBBR was developed in collaboration with the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), the American Institute of Architects (AIA), the Illuminating Engineering Society of North America (IES), the U.S. Green Building Council (USGBC), and the U.S. Department of Energy.

Measurements of absorbed energy distributions in water from pulsed electron beams

International Nuclear Information System (INIS)

Devanney, J.A.

1974-01-01

An evaluation of the use of a holographic interferometer to measure the energy deposition as a function of depth in water from pulsed electron beams, together with a brief description of the interferometer and the technique of generating a hologram are presented. The holographic interferometer is used to measure the energy deposition as a function of depth in water from various pulsed beams of monoenergetic electrons in the energy range from 1.0 to 2.5 MeV. These results are compared to those computed by using a Monte Carlo radiation transport code, ETRAN-15, for the same electron energies. After the discrepancies between the measured and computed results are evaluated, reasonable agreement is found between the measured and computed absorbed energy distributions as a function of depth in water. An evalutation of the response of the interferometer as a function of electron intensities is performed. A comparison among four energy deposition curves that result from the irradiation of water with pulsed electron beams from a Febetron accelerator, model 705, is presented. These pulsed beams were produced by the same vacuum diode with the same charging voltage. The results indicate that the energy distribution of the electrons in the pulsed beam is not always constant. A comparison of the energy deposition curves that result from the irradiation of water with electron pulses from different vacuum diodes but the same charging voltage is presented. These results indicate again that the energy distribution of the electrons in the pulsed beam may vary between vacuum diodes. These differences would not be realized by using a totally absorbing metal calorimeter and Faraday Cup

Treatment of surfaces with low-energy electrons

Science.gov (United States)

Frank, L.; Mikmeková, E.; Lejeune, M.

2017-06-01

Electron-beam-induced deposition of various materials from suitable precursors has represented an established branch of nanotechnology for more than a decade. A specific alternative is carbon deposition on the basis of hydrocarbons as precursors that has been applied to grow various nanostructures including masks for subsequent technological steps. Our area of study was unintentional electron-beam-induced carbon deposition from spontaneously adsorbed hydrocarbon molecules. This process traditionally constitutes a challenge for scanning electron microscopy practice preventing one from performing any true surface studies outside an ultrahigh vacuum and without in-situ cleaning of samples, and also jeopardising other electron-optical devices such as electron beam lithographs. Here we show that when reducing the energy of irradiating electrons sufficiently, the e-beam-induced deposition can be converted to e-beam-induced release causing desorption of hydrocarbons and ultimate cleaning of surfaces in both an ultrahigh and a standard high vacuum. Using series of experiments with graphene samples, we demonstrate fundamental features of e-beam-induced desorption and present results of checks for possible radiation damage using Raman spectroscopy that led to optimisation of the electron energy for damage-free cleaning. The method of preventing carbon contamination described here paves the way for greatly enhanced surface sensitivity of imaging and substantially reduced demands on vacuum systems for nanotechnological applications.

A monochromatic, aberration-corrected, dual-beam low energy electron microscope.

Science.gov (United States)

Mankos, Marian; Shadman, Khashayar

2013-07-01

The monochromatic, aberration-corrected, dual-beam low energy electron microscope (MAD-LEEM) is a novel instrument aimed at imaging of nanostructures and surfaces at sub-nanometer resolution that includes a monochromator, aberration corrector and dual beam illumination. The monochromator reduces the energy spread of the illuminating electron beam, which significantly improves spectroscopic and spatial resolution. The aberration corrector utilizes an electron mirror with negative aberrations that can be used to compensate the aberrations of the LEEM objective lens for a range of electron energies. Dual flood illumination eliminates charging generated when a conventional LEEM is used to image insulating specimens. MAD-LEEM is designed for the purpose of imaging biological and insulating specimens, which are difficult to image with conventional LEEM, Low-Voltage SEM, and TEM instruments. The MAD-LEEM instrument can also be used as a general purpose LEEM with significantly improved resolution. The low impact energy of the electrons is critical for avoiding beam damage, as high energy electrons with keV kinetic energies used in SEMs and TEMs cause irreversible change to many specimens, in particular biological materials. A potential application for MAD-LEEM is in DNA sequencing, which demands imaging techniques that enable DNA sequencing at high resolution and speed, and at low cost. The key advantages of the MAD-LEEM approach for this application are the low electron impact energies, the long read lengths, and the absence of heavy-atom DNA labeling. Image contrast simulations of the detectability of individual nucleotides in a DNA strand have been developed in order to refine the optics blur and DNA base contrast requirements for this application. Copyright © 2013 Elsevier B.V. All rights reserved.

Properties of short-range and long-range correlation energy density functionals from electron-electron coalescence

International Nuclear Information System (INIS)

Gori-Giorgi, Paola; Savin, Andreas

2006-01-01

The combination of density-functional theory with other approaches to the many-electron problem through the separation of the electron-electron interaction into a short-range and a long-range contribution is a promising method, which is raising more and more interest in recent years. In this work some properties of the corresponding correlation energy functionals are derived by studying the electron-electron coalescence condition for a modified (long-range-only) interaction. A general relation for the on-top (zero electron-electron distance) pair density is derived, and its usefulness is discussed with some examples. For the special case of the uniform electron gas, a simple parametrization of the on-top pair density for a long-range only interaction is presented and supported by calculations within the ''extended Overhauser model.'' The results of this work can be used to build self-interaction corrected short-range correlation energy functionals

Interactions between low energy electrons and DNA: a perspective from first-principles simulations

Science.gov (United States)

Kohanoff, Jorge; McAllister, Maeve; Tribello, Gareth A.; Gu, Bin

2017-09-01

DNA damage caused by irradiation has been studied for many decades. Such studies allow us to better assess the dangers posed by radiation, and to increase the efficiency of the radiotherapies that are used to combat cancer. A full description of the irradiation process involves multiple size and time scales. It starts with the interaction of radiation—either photons or swift ions—and the biological medium, which causes electronic excitation and ionisation. The two main products of ionising radiation are thus electrons and radicals. Both of these species can cause damage to biological molecules, in particular DNA. In the long run, this molecular level damage can prevent cells from replicating and can hence lead to cell death. For a long time it was assumed that the main actors in the damage process were the radicals. However, experiments in a seminal paper by the group of Leon Sanche in 2000 showed that low-energy electrons (LEE), such as those generated when ionising biological targets, can also cause bond breaks in biomolecules, and strand breaks in plasmid DNA in particular (Boudaiffa et al 2000 Science 287 1658-60). These results prompted a significant amount of experimental and theoretical work aimed at elucidating the role played by LEE in DNA damage. In this Topical Review we provide a general overview of the problem. We discuss experimental findings and theoretical results hand in hand with the aim of describing the physics and chemistry that occurs during the process of radiation damage, from the initial stages of electronic excitation, through the inelastic propagation of electrons in the medium, the interaction of electrons with DNA, and the chemical end-point effects on DNA. A very important aspect of this discussion is the consideration of a realistic, physiological environment. The role played by the aqueous solution and the amino acids from the histones in chromatin must be considered. Moreover, thermal fluctuations must be incorporated when

On the possibility of obtaining high-energy polarized electrons on Yerevan synchrotron

International Nuclear Information System (INIS)

Melikyan, R.A.

1975-01-01

A possibility of producing high-energy polarized electrons on the Yerevan synchrotron is discussed. A review of a number of low-energy polarized electron sources and of some of experiments with high-energy polarized electrons is given

Low-energy electron diffraction and induced damage in hydrated DNA

International Nuclear Information System (INIS)

Orlando, Thomas M.; Oh, Doogie; Chen Yanfeng; Aleksandrov, Alexandr B.

2008-01-01

Elastic scattering of 5-30 eV electrons within the B-DNA 5 ' -CCGGCGCCGG-3 ' and A-DNA 5 ' -CGCGAATTCGCG-3 ' DNA sequences is calculated using the separable representation of a free-space electron propagator and a curved wave multiple scattering formalism. The disorder brought about by the surrounding water and helical base stacking leads to a featureless amplitude buildup of elastically scattered electrons on the sugar and phosphate groups for all energies between 5 and 30 eV. However, some constructive interference features arising from diffraction are revealed when examining the structural waters within the major groove. These appear at 5-10, 12-18, and 22-28 eV for the B-DNA target and at 7-11, 12-18, and 18-25 eV for the A-DNA target. Although the diffraction depends on the base-pair sequence, the energy dependent elastic scattering features are primarily associated with the structural water molecules localized within 8-10 A spheres surrounding the bases and/or the sugar-phosphate backbone. The electron density buildup occurs in energy regimes associated with dissociative electron attachment resonances, direct electronic excitation, and dissociative ionization. Since diffraction intensity can be localized on structural water, compound H 2 O:DNA states may contribute to energy dependent low-energy electron induced single and double strand breaks

Electronic transport of molecular nanowires by considering of electron hopping energy between the second neighbors

Directory of Open Access Journals (Sweden)

H Rabani

2015-07-01

Full Text Available In this paper, we study the electronic conductance of molecular nanowires by considering the electron hopping between the first and second neighbors with the help Green’s function method at the tight-binding approach. We investigate three types of structures including linear uniform and periodic chains as well as poly(p-phenylene molecule which are embedded between two semi-infinite metallic leads. The results show that in the second neighbor approximation, the resonance, anti-resonance and Fano phenomena occur in the conductance spectra of these structures. Moreover, a new gap is observed at edge of the lead energy band wich its width depends on the value of the electron hopping energy between the second neighbors. In the systems including intrinsic gap, this hopping energy shifts the gap in the energy spectra.

Low Energy Electrons as Probing Tool for Astrochemical Reaction Mechanisms

Science.gov (United States)

Hendrik Bredehöft, Jan; Swiderek, Petra; Hamann, Thorben

. Faraday Discuss., 133 (2006), 393-401 [7] Snow T.P. and Bierbaum V.M.: Ion chemistry in the interstellar medium. Ann. Rev. Analyt. Chem. 1 (2008), 229-259. [8] Nuevo M., Meierhenrich U.J., Muñoz Caro G.M., Dartois E., d'Hendecourt L., Deboffle D., n Auger G., Blanot D., Bredehüft J.H. and Nahon L.: The effects of circularly polarized light on amino acid enantiomers produced by the UV irradiation of interstellar ice analogs. AA 457 (2006), 741-751 [9] Shimamura I and Takayanagi K. (eds): Electron-Molecule Collisions. Plenum Press, New York, USA (1984) [10] Hamann T., Bühler E., Swiderek P.: Low-energy-electron-induced hydroamination of an alkene. Angew Chem Int Ed Engl. 48(25) (2009), 4643-4645.

Relativistic electron beam interaction with a thin target

International Nuclear Information System (INIS)

Gazaix, M.

1981-03-01

This study is concerned with the increasing possibilities of electron energy deposition in thin targets. The thesis theoretical part studies the relativistic electron beam-plasma instability; the Buneman-Pierce instability in limited medium is also studied. In the experimental part, several questions are tentatively answered: - what is the spatial and temporal evolution of the anode material, in temperature and in density. - What sort of interaction is the beam-target interaction; more particularly questions about focusing and energy deposition are studied [fr

Why do Electrons with "Anomalous Energies" appear in High-Pressure Gas Discharges?

Science.gov (United States)

Kozyrev, Andrey; Kozhevnikov, Vasily; Semeniuk, Natalia

2018-01-01

Experimental studies connected with runaway electron beams generation convincingly shows the existence of electrons with energies above the maximum voltage applied to the discharge gap. Such electrons are also known as electrons with "anomalous energies". We explain the presence of runaway electrons having so-called "anomalous energies" according to physical kinetics principles, namely, we describe the total ensemble of electrons with the distribution function. Its evolution obeys Boltzmann kinetic equation. The dynamics of self-consistent electromagnetic field is taken into the account by adding complete Maxwell's equation set to the resulting system of equations. The electrodynamic mechanism of the interaction of electrons with a travelling-wave electric field is analyzed in details. It is responsible for the appearance of electrons with high energies in real discharges.

Radiation defects in InN irradiated with high-energy electrons

International Nuclear Information System (INIS)

Zhivul'ko, V.D.; Mudryj, A.V.; Yakushev, M.V.; Martin, R.; Shaff, V.; Lu, Kh.; Gurskij, A.L.

2013-01-01

The influence of high energy (6 MeV, fluencies 10 15 – 10 18 cm -2 ) electron irradiation on the fundamental absorption and luminescence properties of InN thin films which were grown on sapphire substrates by molecular bean epitaxial has been studied. It is found that electron irradiation increases the electron concentration and band gap energy E g of InN. The shift of the band gap energy E g is a manifestation of the Burshtein-Mossa effect. (authors)

Wettability Modification of Nanomaterials by Low-Energy Electron Flux

Directory of Open Access Journals (Sweden)

Torchinsky I

2009-01-01

Full Text Available Abstract Controllable modification of surface free energy and related properties (wettability, hygroscopicity, agglomeration, etc. of powders allows both understanding of fine physical mechanism acting on nanoparticle surfaces and improvement of their key characteristics in a number of nanotechnology applications. In this work, we report on the method we developed for electron-induced surface energy and modification of basic, related properties of powders of quite different physical origins such as diamond and ZnO. The applied technique has afforded gradual tuning of the surface free energy, resulting in a wide range of wettability modulation. In ZnO nanomaterial, the wettability has been strongly modified, while for the diamond particles identical electron treatment leads to a weak variation of the same property. Detailed investigation into electron-modified wettability properties has been performed by the use of capillary rise method using a few probing liquids. Basic thermodynamic approaches have been applied to calculations of components of solid–liquid interaction energy. We show that defect-free, low-energy electron treatment technique strongly varies elementary interface interactions and may be used for the development of new technology in the field of nanomaterials.

Free electron lasers for transmission of energy in space

Science.gov (United States)

Segall, S. B.; Hiddleston, H. R.; Catella, G. C.

1981-01-01

A one-dimensional resonant-particle model of a free electron laser (FEL) is used to calculate laser gain and conversion efficiency of electron energy to photon energy. The optical beam profile for a resonant optical cavity is included in the model as an axial variation of laser intensity. The electron beam profile is matched to the optical beam profile and modeled as an axial variation of current density. Effective energy spread due to beam emittance is included. Accelerators appropriate for a space-based FEL oscillator are reviewed. Constraints on the concentric optical resonator and on systems required for space operation are described. An example is given of a space-based FEL that would produce 1.7 MW of average output power at 0.5 micrometer wavelength with over 50% conversion efficiency of electrical energy to laser energy. It would utilize a 10 m-long amplifier centered in a 200 m-long optical cavity. A 3-amp, 65 meV electrostatic accelerator would provide the electron beam and recover the beam after it passes through the amplifier. Three to five shuttle flights would be needed to place the laser in orbit.

Energy of auroral electrons and Z mode generation

Science.gov (United States)

Krauss-Varban, D.; Wong, H. K.

1990-01-01

The present consideration of Z-mode radiation generation, in light of observational results indicating that the O mode and second-harmonic X-mode emissions can prevail over the X-mode fundamental radiation when suprathermal electron energy is low, gives attention to whether the thermal effect on the Z-mode dispersion can be equally important, and whether the Z-mode can compete for the available free-energy source. It is found that, under suitable circumstances, the growth rate of the Z-mode can be substantial even for low suprathermal auroral electron energies. Growth is generally maximized for propagation perpendicular to the magnetic field.

Permanent-magnet energy spectrometer for electron beams from radiotherapy accelerators

Energy Technology Data Exchange (ETDEWEB)

McLaughlin, David J.; Shikhaliev, Polad M.; Matthews, Kenneth L. [Department of Physics and Astronomy, Louisiana State University, 202 Nicholson Hall, Baton Rouge, Louisiana 70803-4001 (United States); Hogstrom, Kenneth R., E-mail: hogstrom@lsu.edu; Carver, Robert L.; Gibbons, John P. [Mary Bird Perkins Cancer Center, 4950 Essen Lane, Baton Rouge, Louisiana 70809-3482 and Department of Physics and Astronomy, Louisiana State University, 202 Nicholson Hall, Baton Rouge, Louisiana 70803-4001 (United States); Clarke, Taylor; Henderson, Alexander; Liang, Edison P. [Physics and Astronomy Department, Rice University, 6100 Main MS-61, Houston, Texas 77005-1827 (United States)

2015-09-15

Purpose: The purpose of this work was to adapt a lightweight, permanent magnet electron energy spectrometer for the measurement of energy spectra of therapeutic electron beams. Methods: An irradiation geometry and measurement technique were developed for an approximately 0.54-T, permanent dipole magnet spectrometer to produce suitable latent images on computed radiography (CR) phosphor strips. Dual-pinhole electron collimators created a 0.318-cm diameter, approximately parallel beam incident on the spectrometer and an appropriate dose rate at the image plane (CR strip location). X-ray background in the latent image, reduced by a 7.62-cm thick lead block between the pinhole collimators, was removed using a fitting technique. Theoretical energy-dependent detector response functions (DRFs) were used in an iterative technique to transform CR strip net mean dose profiles into energy spectra on central axis at the entrance to the spectrometer. These spectra were transformed to spectra at 95-cm source to collimator distance (SCD) by correcting for the energy dependence of electron scatter. The spectrometer was calibrated by comparing peak mean positions in the net mean dose profiles, initially to peak mean energies determined from the practical range of central-axis percent depth-dose (%DD) curves, and then to peak mean energies that accounted for how the collimation modified the energy spectra (recalibration). The utility of the spectrometer was demonstrated by measuring the energy spectra for the seven electron beams (7–20 MeV) of an Elekta Infinity radiotherapy accelerator. Results: Plots of DRF illustrated their dependence on energy and position in the imaging plane. Approximately 15 iterations solved for the energy spectra at the spectrometer entrance from the measured net mean dose profiles. Transforming those spectra into ones at 95-cm SCD increased the low energy tail of the spectra, while correspondingly decreasing the peaks and shifting them to slightly lower

Permanent-magnet energy spectrometer for electron beams from radiotherapy accelerators.

Science.gov (United States)

McLaughlin, David J; Hogstrom, Kenneth R; Carver, Robert L; Gibbons, John P; Shikhaliev, Polad M; Matthews, Kenneth L; Clarke, Taylor; Henderson, Alexander; Liang, Edison P

2015-09-01

The purpose of this work was to adapt a lightweight, permanent magnet electron energy spectrometer for the measurement of energy spectra of therapeutic electron beams. An irradiation geometry and measurement technique were developed for an approximately 0.54-T, permanent dipole magnet spectrometer to produce suitable latent images on computed radiography (CR) phosphor strips. Dual-pinhole electron collimators created a 0.318-cm diameter, approximately parallel beam incident on the spectrometer and an appropriate dose rate at the image plane (CR strip location). X-ray background in the latent image, reduced by a 7.62-cm thick lead block between the pinhole collimators, was removed using a fitting technique. Theoretical energy-dependent detector response functions (DRFs) were used in an iterative technique to transform CR strip net mean dose profiles into energy spectra on central axis at the entrance to the spectrometer. These spectra were transformed to spectra at 95-cm source to collimator distance (SCD) by correcting for the energy dependence of electron scatter. The spectrometer was calibrated by comparing peak mean positions in the net mean dose profiles, initially to peak mean energies determined from the practical range of central-axis percent depth-dose (%DD) curves, and then to peak mean energies that accounted for how the collimation modified the energy spectra (recalibration). The utility of the spectrometer was demonstrated by measuring the energy spectra for the seven electron beams (7-20 MeV) of an Elekta Infinity radiotherapy accelerator. Plots of DRF illustrated their dependence on energy and position in the imaging plane. Approximately 15 iterations solved for the energy spectra at the spectrometer entrance from the measured net mean dose profiles. Transforming those spectra into ones at 95-cm SCD increased the low energy tail of the spectra, while correspondingly decreasing the peaks and shifting them to slightly lower energies. Energy calibration

Low energy electron attachment to the uracil molecule

International Nuclear Information System (INIS)

Hanel, G.; Gstir, B.; Denifl, S.; Scheier, P.; Maerk, T.D.; Farizon, B.; Farizon, M.

2002-01-01

Using a recently constructed high resolution crossed beam apparatus involving a hemispherical electron monochromator, electron attachment to the uracil molecule C 4 H 4 N 2 O 2 was studied. The electron energy range investigated was in the region between 0 and 12 eV. What will happen when slow electrons are colliding with the cellular RNA compound uracil was the objective of this investigation. The following anion fragments were detected: (C 4 H 3 N 2 O 2 ) - , OCN - , (H 2 C 3 NO) - , CN - , O - . The most important result was that within the detection efficiency any traces of the parent anion were observed. The most intense fragment anion appeared on a mass to charge ratio 111 amu., it corresponds to a uracil molecule missing one hydrogen. Another observation was whereas the parent minus H anion is observed at zero electron energy, all other fragments appear in other range. (nevyjel)

Electron Energy Confinement for HHFW Heating and Current Drive Phasing on NSTX

International Nuclear Information System (INIS)

Hosea, J.C.; Bernabei, S.; Biewer, T.; LeBlanc, B.; Phillips, C.K.; Wilson, J.R.; Stutman, D.; Ryan, P.; Swain, D.W.

2005-01-01

Thomson scattering laser pulses are synchronized relative to modulated HHFW power to permit evaluation of the electron energy confinement time during and following HHFW pulses for both heating and current drive antenna phasing. Profile changes resulting from instabilities require that the total electron stored energy, evaluated by integrating the midplane electron pressure P(sub)e(R) over the magnetic surfaces prescribed by EFIT analysis, be used to derive the electron energy confinement time. Core confinement is reduced during a sawtooth instability but, although the electron energy is distributed outward by the sawtooth, the bulk electron energy confinement time is essentially unaffected. The radial deposition of energy into the electrons is noticeably more peaked for current drive phasing (longer wavelength excitation) relative to that for heating phasing (shorter wavelength excitation) as is expected theoretically. However, the power delivered to the core plasma is reduced consider ably for the current drive phasing, indicating that surface/peripheral damping processes play a more important role for this case

Treatment of surfaces with low-energy electrons

Energy Technology Data Exchange (ETDEWEB)

Frank, L., E-mail: ludek@isibrno.cz [Institute of Scientific Instruments of the CAS, v.v.i., Královopolská 147, 61264 Brno (Czech Republic); Mikmeková, E. [Institute of Scientific Instruments of the CAS, v.v.i., Královopolská 147, 61264 Brno (Czech Republic); FEI Company, Achtseweg Noord 5, 5651 GG Eindhoven (Netherlands); Lejeune, M. [LPMC – Faculte des Sciences d’Amiens, Universite de Picardie Jules Verne, 33 rue Saint Leu, 80039 Amiens Cedex 2 (France)

2017-06-15

Highlights: • Using proper irradiation parameters, adsorbed hydrocarbons are released from surfaces. • Slow electrons remove hydrocarbons instead of depositing carbon. • Prolonged irradiation with very slow electrons does not create defects in graphene. - Abstract: Electron-beam-induced deposition of various materials from suitable precursors has represented an established branch of nanotechnology for more than a decade. A specific alternative is carbon deposition on the basis of hydrocarbons as precursors that has been applied to grow various nanostructures including masks for subsequent technological steps. Our area of study was unintentional electron-beam-induced carbon deposition from spontaneously adsorbed hydrocarbon molecules. This process traditionally constitutes a challenge for scanning electron microscopy practice preventing one from performing any true surface studies outside an ultrahigh vacuum and without in-situ cleaning of samples, and also jeopardising other electron-optical devices such as electron beam lithographs. Here we show that when reducing the energy of irradiating electrons sufficiently, the e-beam-induced deposition can be converted to e-beam-induced release causing desorption of hydrocarbons and ultimate cleaning of surfaces in both an ultrahigh and a standard high vacuum. Using series of experiments with graphene samples, we demonstrate fundamental features of e-beam-induced desorption and present results of checks for possible radiation damage using Raman spectroscopy that led to optimisation of the electron energy for damage-free cleaning. The method of preventing carbon contamination described here paves the way for greatly enhanced surface sensitivity of imaging and substantially reduced demands on vacuum systems for nanotechnological applications.

Modified electron acoustic field and energy applied to observation data

Energy Technology Data Exchange (ETDEWEB)

Abdelwahed, H. G., E-mail: hgomaa-eg@yahoo.com, E-mail: hgomaa-eg@mans.edu.eg [College of Science and Humanitarian Studies, Physics Department, Prince Sattam Bin Abdul Aziz University, Alkharj 11942 (Saudi Arabia); Theoretical Physics Research Group, Physics Department, Faculty of Science, Mansoura University, Mansoura 35516 (Egypt); El-Shewy, E. K. [Theoretical Physics Research Group, Physics Department, Faculty of Science, Mansoura University, Mansoura 35516 (Egypt)

2016-08-15

Improved electrostatic acoustic field and energy have been debated in vortex trapped hot electrons and fluid of cold electrons with pressure term plasmas. The perturbed higher-order modified-Korteweg-de Vries equation (PhomKdV) has been worked out. The effect of trapping and electron temperatures on the electro-field and energy properties in auroral plasmas has been inspected.

The application analysis of high energy electron accelerator in food irradiation processing

International Nuclear Information System (INIS)

Deng Wenmin; Chen Hao; Feng Lei; Zhang Yaqun; Chen Xun; Li Wenjun; Xiang Chengfen; Pei Ying; Wang Zhidong

2012-01-01

Irradiation technology of high energy electron accelerator has been highly concerned in food processing industry with its fast development, especially in the field of food irradiation processing. In this paper, equipment and research situation of high energy electron accelerator were collected, meanwhile, the similarities and differences between high energy electron beam and 60 Co γ-rays were discussed. In order to provide more references of high energy electron beam irradiation, the usages of high energy electron in food irradiation processing was prospected. These information would promote the development of domestic food irradiation industry and give a useful message to irradiation enterprises and researchers. (authors)

Secondary Electrons as an Energy Source for Life.

Science.gov (United States)

Stelmach, Kamil B; Neveu, Marc; Vick-Majors, Trista J; Mickol, Rebecca L; Chou, Luoth; Webster, Kevin D; Tilley, Matt; Zacchei, Federica; Escudero, Cristina; Flores Martinez, Claudio L; Labrado, Amanda; Fernández, Enrique J G

2018-01-01

Life on Earth is found in a wide range of environments as long as the basic requirements of a liquid solvent, a nutrient source, and free energy are met. Previous hypotheses have speculated how extraterrestrial microbial life may function, among them that particle radiation might power living cells indirectly through radiolytic products. On Earth, so-called electrophilic organisms can harness electron flow from an extracellular cathode to build biomolecules. Here, we describe two hypothetical mechanisms, termed "direct electrophy" and "indirect electrophy" or "fluorosynthesis," by which organisms could harness extracellular free electrons to synthesize organic matter, thus expanding the ensemble of potential habitats in which extraterrestrial organisms might be found in the Solar System and beyond. The first mechanism involves the direct flow of secondary electrons from particle radiation to a microbial cell to power the organism. The second involves the indirect utilization of impinging secondary electrons and a fluorescing molecule, either biotic or abiotic in origin, to drive photosynthesis. Both mechanisms involve the attenuation of an incoming particle's energy to create low-energy secondary electrons. The validity of the hypotheses is assessed through simple calculations showing the biomass density attainable from the energy supplied. Also discussed are potential survival strategies that could be used by organisms living in possible habitats with a plentiful supply of secondary electrons, such as near the surface of an icy moon. While we acknowledge that the only definitive test for the hypothesis is to collect specimens, we also describe experiments or terrestrial observations that could support or nullify the hypotheses. Key Words: Radiation-Electrophiles-Subsurface life. Astrobiology 18, 73-85.

Treatment of surfaces with low-energy electrons

Czech Academy of Sciences Publication Activity Database

Frank, Luděk; Mikmeková, Eliška; Lejeune, M.

2017-01-01

Roč. 407, JUN 15 (2017), s. 105-108 ISSN 0169-4332 R&D Projects: GA TA ČR(CZ) TE01020118; GA MŠk(CZ) LO1212; GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : Low- energy electrons * Electron beam induced release * Graphene * Ultimate cleaning of surfaces Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering OBOR OECD: Nano-processes (applications on nano-scale) Impact factor: 3.387, year: 2016

Spontaneous and stimulated emission induced by an electron, electron bunch, and electron beam in a plasma

International Nuclear Information System (INIS)

Kuzelev, M V; Rukhadze, A A

2008-01-01

Two fundamental mechanisms - the Cherenkov effect and anomalous Doppler effect - underlying the emission by an electron during its superluminal motion in medium are considered. Cherenkov emission induced by a single electron and a small electron bunch is spontaneous. In the course of spontaneous Cherenkov emission, the translational motion of an electron is slowed down and the radiation energy grows linearly with time. As the number of radiating electrons increases, Cherenkov emission becomes stimulated. Stimulated Cherenkov emission represents a resonance beam instability. This emission process is accompanied by longitudinal electron bunching in the beam or by the breaking of an electron bunch into smaller bunches, in which case the radiation energy grows exponentially with time. In terms of the longitudinal size L e of the electron bunch there is a transition region λ e 0 -1 between the spontaneous and stimulated Cherenkov effects, where λ is the average radiation wavelength, and δ 0 is the dimensionless (in units of the radiation frequency) growth rate of the Cherenkov beam instability. The range to the left of this region is dominated by spontaneous emission, whereas the range to the right of this region is dominated by stimulated emission. In contrast to the Vavilov-Cherenkov effect, the anomalous Doppler effect should always (even for a single electron) be considered as stimulated, because it can only be explained by accounting for the reverse action of the radiation field on the moving electron. During stimulated emission in conditions where anomalous Doppler effect shows itself, an electron is slowed down and spins up; in this case, the radiation energy grows exponentially with time. (reviews of topical problems)

Jovian electrons as an instrument of investigation of the interplanetary medium structure

International Nuclear Information System (INIS)

Daibog, E; Lazutin, L; Logachev, Yu; Kecskemety, K

2016-01-01

Electrons accelerated in the Jupiter magnetosphere are usually registered by near-earth spacecraft under optimal magnetic connection between the Earth and Jupiter, taking place once in 13 months (Earth- Jupiter synodic period). During the period of minimal solar activity between 23 and 24 cycles in 2007-2009 electrons of MeV energies were observed practically at each of 14 solar rotations (more than a year), which requires extremely long quasistationary state of inner heliosphere with constant Earth- Jupiter connection. To explain this situation the model with long living magnetic trap, co-rotating with the Sun, was suggested. Passing by the Jupiter this trap captures electrons, which then are registered by subsequent passing of the trap by the Earth. (paper)

Medium energy measurements of N-N parameters. Final technical report, April 1, 1994--September 30, 1996