Ionization front accelerator

International Nuclear Information System (INIS)

Olson, C.L.

1975-01-01

In a recently proposed linear collective accelerator, ions are accelerated in a steep, moving potential well created at the head of an intense relativistic electron beam. The steepness of the potential well and its motion are controlled by the external ionization of a suitable background gas. Calculations concerning optimum choices for the background gas and the ionization method are presented; a two-step photoionization process employing Cs vapor is proposed. In this process, a super-radiant light source is used to excite the gas, and a UV laser is used to photoionize the excited state. The appropriate line widths and coupled ionization growth rate equations are discussed. Parameter estimates are given for a feasibility experiment, for a 1 GeV proton accelerator, and for a heavy ion accelerator (50 MeV/nucleon uranium). (auth)

Sri Lanka: Background and U.S. Relations

Science.gov (United States)

2009-06-04

account for about four-fifths of the country’s exports, including garments , textiles, gems, as well as agricultural goods. Tourism and repatriated...May 28, 2009. Sri Lanka: Background and U.S. Relations Congressional Research Service 13 reform and privatization of state-owned industries in...port facilities in Gwadar, Pakistan; Chittagong, Bangladesh ; and Sittwe, Burma.75 Colombo was also

A novel approach to electron data background treatment in an online wide-angle spectrometer for laser-accelerated ion and electron bunches

Science.gov (United States)

Lindner, F. H.; Bin, J. H.; Englbrecht, F.; Haffa, D.; Bolton, P. R.; Gao, Y.; Hartmann, J.; Hilz, P.; Kreuzer, C.; Ostermayr, T. M.; Rösch, T. F.; Speicher, M.; Parodi, K.; Thirolf, P. G.; Schreiber, J.

2018-01-01

Laser-based ion acceleration is driven by electrical fields emerging when target electrons absorb laser energy and consecutively leave the target material. A direct correlation between these electrons and the accelerated ions is thus to be expected and predicted by theoretical models. We report on a modified wide-angle spectrometer, allowing the simultaneous characterization of angularly resolved energy distributions of both ions and electrons. Equipped with online pixel detectors, the RadEye1 detectors, the investigation of this correlation gets attainable on a single shot basis. In addition to first insights, we present a novel approach for reliably extracting the primary electron energy distribution from the interfering secondary radiation background. This proves vitally important for quantitative extraction of average electron energies (temperatures) and emitted total charge.

Full simulation of the beam-related backgrounds at the ILC

Energy Technology Data Exchange (ETDEWEB)

Schuetz, Anne [DESY (Germany); KIT (Germany)

2016-07-01

The ILC has been proposed as the next machine at the energy frontier and a Technical Design Report was presented in 2012. As part of the site-specific studies to prepare the hosting of the ILC in Japan, the final focus region of the ILC had to be adapted. In this contribution, updated results for the beam-related background as well as new results for the backgrounds originating from the beam dump are presented. The beam-related backgrounds are simulated using GuineaPig and are then propagated through the full simulation of the SiD detector. The impact of various modifications in the final-focus region on the detector occupancies are then evaluated. For the neutron background from the beam dump, the FLUKA simulation suite is used, which is well established for dosimetry and shielding studies. With this program, the effect of the neutrons from the ILC beam dumps on the ILC detectors are studied.

Re-Identification of the Many-World Background of Special Relativity as Four-World Background. Part II

Directory of Open Access Journals (Sweden)

Adekugbe A. O. J.

2011-01-01

Full Text Available The re-identification of the many-world background of the special theory of relativity (SR as four-world background in the first part of this paper (instead of two-wold background isolated in the initial papers, is concluded in this second part. The flat two-dimensional intrinsic spacetime, which underlies the flat four-dimensional spacetime in each universe, introduced as ansatz in the initial paper, is derived formally within the four-world picture. The identical magnitudes of masses, identical sizes and identical shapes of the four members of every quartet of symmetry-partner particles or objects in the four universes are shown. The immutability of Lorentz invariance on flat spacetime of SR in each of the four universes is shown to arise as a consequence of the perfect symmetry of relative motion at all times among the four members of every quartet of symmetry-partner particles and objects in the four universes. The perfect symmetry of relative motions at all times, coupled with the identical magnitudes of masses, identical sizes and identical shapes, of the members of every quartet of symmetry-partner particles and objects in the four universes, guarantee perfect symmetry of state among the universes.

Research activities related to accelerator-based transmutation at PSI

International Nuclear Information System (INIS)

Wydler, P.

1993-01-01

Transmutation of actinides and fission products using reactors and other types of nuclear systems may play a role in future waste management schemes. Possible advantages of separation and transmutation are: volume reductions, the re-use of materials, the avoidance of a cumulative risk, and limiting the duration of the risk. With its experience in reactor physics, accelerator-based physics, and the development of the SINQ spallation neutron source, PSI is in a good position to perform basic theoretical and experimental studies relating to the accelerator-based transmutation of actinides. Theoretical studies at PSI have been concentrated, so far, on systems in which protons are used directly to transmute actinides. With such systems and appropriate recycling schemes, the studies showed that considerable reduction factors for long-term toxicity can be obtained. With the aim of solving some specific data and method problems related to these types of systems, a programme of differential and integral measurements at the PSI ring accelerator has been initiated. In a first phase of this programme, thin samples of actinides will be irradiated with 590 MeV protons, using an existing irradiation facility. The generated spallation and fission products will be analysed using different experimental techniques, and the results will be compared with theoretical predictions based on high-energy nucleon-meson transport calculations. The principal motivation for these experiments is to resolve discrepancies observed between calculations based on different high-energy fission models. In a second phase of the programme, it is proposed to study the neutronic behaviour of multiplying target-blanket assemblies with the help of zero-power experiments set up at a separate, dedicated beam line of the accelerator. (author) 3 figs., 2 tabs., 8 refs

Half a century of particle accelerators - 1950-2000

International Nuclear Information System (INIS)

Marin, P.

2009-01-01

In a lively historical account the author tells of the extraordinary progress made in accelerator physics since World War II. He focuses mainly on the history of French accelerators which evolved from small electrostatic accelerators purchased abroad to complex and powerful storage rings and colliders built by French engineers and physicists. He shows how these machines served not only particle physicists, but also researchers working with synchrotron light. He recalls how these two scientific communities with such different backgrounds learned how to work together. The author was an accelerator physicist, and a project leader who played a key role in storage ring R and D, as well as in accelerator construction and operation. He describes the international context of the period, and relates the discussions on scientific policy issues of the time. He tells us about the technical challenges to be overcome and discusses the question of maintaining the balance between national development and international involvement. A number of important yet unknown features of this scientific adventure are related. This short history also includes his thoughts about the gestation of large scientific instruments which, no doubt, will interest researchers involved in 'big science'

Modeling of Particle Acceleration at Multiple Shocks Via Diffusive Shock Acceleration: Preliminary Results

Science.gov (United States)

Parker, L. N.; Zank, G. P.

2013-12-01

Successful forecasting of energetic particle events in space weather models require algorithms for correctly predicting the spectrum of ions accelerated from a background population of charged particles. We present preliminary results from a model that diffusively accelerates particles at multiple shocks. Our basic approach is related to box models (Protheroe and Stanev, 1998; Moraal and Axford, 1983; Ball and Kirk, 1992; Drury et al., 1999) in which a distribution of particles is diffusively accelerated inside the box while simultaneously experiencing decompression through adiabatic expansion and losses from the convection and diffusion of particles outside the box (Melrose and Pope, 1993; Zank et al., 2000). We adiabatically decompress the accelerated particle distribution between each shock by either the method explored in Melrose and Pope (1993) and Pope and Melrose (1994) or by the approach set forth in Zank et al. (2000) where we solve the transport equation by a method analogous to operator splitting. The second method incorporates the additional loss terms of convection and diffusion and allows for the use of a variable time between shocks. We use a maximum injection energy (Emax) appropriate for quasi-parallel and quasi-perpendicular shocks (Zank et al., 2000, 2006; Dosch and Shalchi, 2010) and provide a preliminary application of the diffusive acceleration of particles by multiple shocks with frequencies appropriate for solar maximum (i.e., a non-Markovian process).

Pair of accelerated black holes in a de Sitter background: The dS C metric

International Nuclear Information System (INIS)

Dias, Oscar J.C.; Lemos, Jose P.S.

2003-01-01

Following the work of Kinnersley and Walker for flat spacetimes, we analyzed the anti-de Sitter C metric in a previous paper. In this paper we study the de Sitter C metric (dS C metric). The C metric with a generic cosmological constant and other extra parameters was introduced by Plebanski and Demianski. When one then sets to zero some of the extra parameters, and works with a positive cosmological constant, one has the dS C metric which has been analyzed and physically interpreted by Podolsky and Griffiths. It describes a pair of accelerated black holes in the dS background with the acceleration being provided (in addition to the cosmological constant) by a strut that pushes away the two black holes or, alternatively, by a string that pulls them. We extend their analysis mainly in four directions. First, we draw the Carter-Penrose diagrams of the massless uncharged dS C metric, of the massive uncharged dS C metric and of the massive charged dS C metric. These diagrams allow us to clearly identify the presence of two dS black holes and to conclude that they cannot interact gravitationally. Second, we reexamine the embedding of the dS C metric in the 5D Minkowski spacetime and we represent the motion of the dS C metric origin in the dS 4-hyperboloid as well as the localization of the strut. Third, we comment on the physical properties of the strut that connects the two black holes. Finally, we find the range of parameters that correspond to nonextreme black holes, extreme black holes, and naked particles

Plasma-focused cyclic accelerators

International Nuclear Information System (INIS)

Mondelli, A.A.; Chernin, D.P.

1985-01-01

The use of ambient plasma to neutralize the transverse forces of an intense particle beam has been known for many years. Most recently, the so-called ion-focused regime (IFR) for beam propagation has been used as a means of focusing intense electron beams in linear accelerators and suggested for injecting an electron beam across magnetic field lines into a high-current cyclic accelerator. One technique for generating the required background plasma for IFR propagation is to use a laser to ionize ambient gas in the accelerator chamber. This paper discusses an alternative means of plasma production for IFR, viz. by using RF breakdown. For this approach the accelerator chamber acts as a waveguide. This technique is not limited to toroidal accelerators. It may be applied to any accelerator or recirculator geometry as well as for beam steering and for injection or extraction of beams in closed accelerator configurations

Single atom counting with accelerators

Energy Technology Data Exchange (ETDEWEB)

Woelfli, W [Eidgenoessische Technische Hochschule, Zurich (Switzerland)

1984-02-01

Direct detection of radioisotopes with conventional mass spectrometers is possible when the potential background atoms, in particular stable isotopes of the same mass (isobars) or molecules of similar mass are present in sufficiently low concentrations. Most of the long lived radioisotopes of interest for dating purposes however, occur in such small concentrations that their peak in the mass spectrum is obscured by the stable isobar and molecule distributions. The key idea of the new AMS technique which allows us to measure directly such small concentrations is the acceleration of the sample atoms to MeV energies and to use various filter processes and particle identification techniques developed for nuclear physics research to eliminate the isobaric and molecular interferences. The detection methods used for each radioisotope depend on the dominant background atoms and these in turn depend on the specific accelerator used. The problems encountered in transforming an existing particle accelerator into a high precision dating tool are considerable and have been solved only recently for one type of accelerator, notably the tandem Van de Graaff. For this reason the description of the AMS method and some of its applications is restricted to this type of accelerator only.

Background factors related to and/or influencing occupation in mentally disordered offenders.

Science.gov (United States)

Lindstedt, Helena; Ivarsson, Ann-Britt; Söderlund, Anne

2006-09-01

Knowledge of background and occupational related factors of mentally disordered offenders are missing. It is essential to understand these issues when planning discharge from forensic psychiatric hospital care to enable community dwelling. One aim was to investigate mentally disordered offenders' background factors, confidence in and how they value occupations. Another aim was to investigate MDOs background factors' in relation to and the influences on Occupational Performance and Social Participation. Data was collected with an explorative, correlative design after informed consent, from 74 mentally disordered offenders (mean age 34,2) cared for in forensic psychiatric hospitals. Assessments were Allen Cognitive Level Screen, Capability to Perform Daily Occupations, Interview Schedule of Social Interaction, Manchester Short Assessment of Quality of Life, Self-efficacy Scale and Importance scale. Eight background factors were assembled from the individual forensic psychiatric investigation. Most of the investigated background factors relate to and half of them influence occupational performance, particular the cognitive aspect of occupational performance. The influences on occupation originate from adulthood, such as suffering from schizophrenia, psycho/social problems, and having performed violent crimes. These findings indicate that staff in forensic hospital care should initiate rehabilitation with knowledge about MDOs' complex daily occupations. For avoiding information bias, information gathering preceding treatment planning should be performed in collaboration between caring staff and mentally disordered offenders.

Data Series Subtraction with Unknown and Unmodeled Background Noise

Science.gov (United States)

Vitale, Stefano; Congedo, Giuseppe; Dolesi, Rita; Ferroni, Valerio; Hueller, Mauro; Vetrugno, Daniele; Weber, William Joseph; Audley, Heather; Danzmann, Karsten; Diepholz, Ingo;

Acceleration Modes and Transitions in Pulsed Plasma Accelerators

Science.gov (United States)

Polzin, Kurt A.; Greve, Christine M.

2018-01-01

Pulsed plasma accelerators typically operate by storing energy in a capacitor bank and then discharging this energy through a gas, ionizing and accelerating it through the Lorentz body force. Two plasma accelerator types employing this general scheme have typically been studied: the gas-fed pulsed plasma thruster and the quasi-steady magnetoplasmadynamic (MPD) accelerator. The gas-fed pulsed plasma accelerator is generally represented as a completely transient device discharging in approximately 1-10 microseconds. When the capacitor bank is discharged through the gas, a current sheet forms at the breech of the thruster and propagates forward under a j (current density) by B (magnetic field) body force, entraining propellant it encounters. This process is sometimes referred to as detonation-mode acceleration because the current sheet representation approximates that of a strong shock propagating through the gas. Acceleration of the initial current sheet ceases when either the current sheet reaches the end of the device and is ejected or when the current in the circuit reverses, striking a new current sheet at the breech and depriving the initial sheet of additional acceleration. In the quasi-steady MPD accelerator, the pulse is lengthened to approximately 1 millisecond or longer and maintained at an approximately constant level during discharge. The time over which the transient phenomena experienced during startup typically occur is short relative to the overall discharge time, which is now long enough for the plasma to assume a relatively steady-state configuration. The ionized gas flows through a stationary current channel in a manner that is sometimes referred to as the deflagration-mode of operation. The plasma experiences electromagnetic acceleration as it flows through the current channel towards the exit of the device. A device that had a short pulse length but appeared to operate in a plasma acceleration regime different from the gas-fed pulsed plasma

Modeling Lost-Particle Accelerator Backgrounds in PEP-II Using LPTURTLE

CERN Document Server

Fieguth, Theodore; Kozanecki, Witold

2005-01-01

Background studies during the design, construction, commissioning, operation and improvement of BaBar and PEP-II have been greatly influenced by results from a program referred to as LPTURTLE (Lost Particle TURTLE a modified version of Decay TURTLE) which was originally conceived for the purpose of studying gas background for SLC. This venerable program is still in use today. We describe its use, capabilities and improvements and refer to current results now being applied to BaBar.

CLAWS. Beam background monitoring in the commissioning of SuperKEKB

Energy Technology Data Exchange (ETDEWEB)

Gabriel, Miroslav; Windel, Hendrik; Kolk, Naomi van der; Simon, Frank [Max Planck Institute for Physics (Germany)

2016-07-01

The background levels, in particular those originating from the continuous injection to maximize luminosity, are a concern for the inner vertex detector of Belle-II at the SuperKEKB accelerator. To better understand this background, and in particular its time dependence, dedicated measurements will be made during the commissioning phase of the accelerator, scheduled to begin in February 2016. One of the detectors for these measurements, CLAWS, is based on scintillators coupled to SiPMs which were originally developed for timing measurements of hadronic showers in the CALICE calorimeters. The data acquisition is based on digitizers with very deep buffers allowing the continuous recording of more than 1000 revolutions of the accelerator to provide a detailed analysis of the evolution of the background levels after injection. In this contribution, we present the overall CLAWS setup, the technical solutions adopted for the data acquisition and analysis, and discuss the performance of the detector elements.

An Accelerated Testing Approach for Automated Vehicles with Background Traffic Described by Joint Distributions

OpenAIRE

Huang, Zhiyuan; Lam, Henry; Zhao, Ding

2017-01-01

This paper proposes a new framework based on joint statistical models for evaluating risks of automated vehicles in a naturalistic driving environment. The previous studies on the Accelerated Evaluation for automated vehicles are extended from multi-independent-variate models to joint statistics. The proposed toolkit includes exploration of the rare event (e.g. crash) sets and construction of accelerated distributions for Gaussian Mixture models using Importance Sampling techniques. Furthermo...

JKJ accelerator timing system

International Nuclear Information System (INIS)

Ohmori, C.; Mori, Y.; Yoshii, M.; Yamamoto, M.

2001-01-01

The JKJ (JAERl-KEK Joint Project) accelerator complex consists of the linear accelerator, 3 GeV and 50 GeV synchrotrons. To minimize the beam loss during the beam transfer from the 3 GeV synchrotron to the 50 GeV one, the synchronization of the two RF system of the rings is very important. To reduce the background from the high and low momentum neutron, the neutron beam chopper will be employed. The 3 GeV RF will be also synchronized to the chopper timing when the beam goes to the neutron facility. The whole timing control system of these accelerators and chopper will be described. (author)

Convectively driven decadal zonal accelerations in Earth's fluid core

Science.gov (United States)

More, Colin; Dumberry, Mathieu

2018-04-01

Azimuthal accelerations of cylindrical surfaces co-axial with the rotation axis have been inferred to exist in Earth's fluid core on the basis of magnetic field observations and changes in the length-of-day. These accelerations have a typical timescale of decades. However, the physical mechanism causing the accelerations is not well understood. Scaling arguments suggest that the leading order torque averaged over cylindrical surfaces should arise from the Lorentz force. Decadal fluctuations in the magnetic field inside the core, driven by convective flows, could then force decadal changes in the Lorentz torque and generate zonal accelerations. We test this hypothesis by constructing a quasi-geostrophic model of magnetoconvection, with thermally driven flows perturbing a steady, imposed background magnetic field. We show that when the Alfvén number in our model is similar to that in Earth's fluid core, temporal fluctuations in the torque balance are dominated by the Lorentz torque, with the latter generating mean zonal accelerations. Our model reproduces both fast, free Alfvén waves and slow, forced accelerations, with ratios of relative strength and relative timescale similar to those inferred for the Earth's core. The temporal changes in the magnetic field which drive the time-varying Lorentz torque are produced by the underlying convective flows, shearing and advecting the magnetic field on a timescale associated with convective eddies. Our results support the hypothesis that temporal changes in the magnetic field deep inside Earth's fluid core drive the observed decadal zonal accelerations of cylindrical surfaces through the Lorentz torque.

Mass-Discrepancy Acceleration Relation: A Natural Outcome of Galaxy Formation in Cold Dark Matter Halos.

Science.gov (United States)

Ludlow, Aaron D; Benítez-Llambay, Alejandro; Schaller, Matthieu; Theuns, Tom; Frenk, Carlos S; Bower, Richard; Schaye, Joop; Crain, Robert A; Navarro, Julio F; Fattahi, Azadeh; Oman, Kyle A

2017-04-21

We analyze the total and baryonic acceleration profiles of a set of well-resolved galaxies identified in the eagle suite of hydrodynamic simulations. Our runs start from the same initial conditions but adopt different prescriptions for unresolved stellar and active galactic nuclei feedback, resulting in diverse populations of galaxies by the present day. Some of them reproduce observed galaxy scaling relations, while others do not. However, regardless of the feedback implementation, all of our galaxies follow closely a simple relationship between the total and baryonic acceleration profiles, consistent with recent observations of rotationally supported galaxies. The relation has small scatter: Different feedback implementations-which produce different galaxy populations-mainly shift galaxies along the relation rather than perpendicular to it. Furthermore, galaxies exhibit a characteristic acceleration g_{†}, above which baryons dominate the mass budget, as observed. These observations, consistent with simple modified Newtonian dynamics, can be accommodated within the standard cold dark matter paradigm.

Self-accelerating universe in Galileon cosmology

International Nuclear Information System (INIS)

Silva, Fabio P.; Koyama, Kazuya

2009-01-01

We present a cosmological model with a solution that self-accelerates at late times without signs of ghost instabilities on small scales. The model is a natural extension of the Brans-Dicke (BD) theory including a nonlinear derivative interaction, which appears in a theory with the Galilean shift symmetry. The existence of the self-accelerating universe requires a negative BD parameter but, thanks to the nonlinear term, small fluctuations around the solution are stable on small scales. General relativity is recovered at early times and on small scales by this nonlinear interaction via the Vainshtein mechanism. At late time, gravity is strongly modified and the background cosmology shows a phantomlike behavior and the growth rate of structure formation is enhanced. Thus this model leaves distinct signatures in cosmological observations and it can be distinguished from standard LCDM cosmology.

IAE pulsed electrostatic accelerator

International Nuclear Information System (INIS)

Afanas'ev, V.P.; Ganzhelyuk, M.L.; Kozlov, L.D.; Koltypin, E.A.; Molchanov, Yu.D.; Otroshchenko, G.A.; Yan'kov, G.B.

1976-01-01

The modernized pulse electrostatic accelerator using the klystron ion grouping and the beam interruption system prior to acceleration is described. The accelerator is modernized in order to improve parameters of a current pulse and to decrease the background in the measurement room. The ion beam of needed dimensions is obtained with the help of a high-frequency source and a beam grouping and deflection system. The general view of the beam grouping and deflection system is shown. The ion beam forming process is considered in detail. The modernized electrostatic accelerator permits to obtain a pulse current with a pulse length of 1.5 ns and an amplitude of 1.5 - 2 μA. With the repetition frequency of 2 MHz, the average target current is about 6 μA

Relativity matters from Einstein's EMC2 to laser particle acceleration and quark-gluon plasma

CERN Document Server

Rafelski, Johann

2017-01-01

Rafelski presents Special Relativity in a language deemed accessible to students without any topical preparation - avoiding the burden of geometry, tensor calculus, and space-time symmetries – and yet advancing in highly contemporary context all the way to research frontiers. Special Relativity is presented such that nothing remains a paradox or just apparent, but rather is explained. A text of similar character, content, and scope, has not been available before. This book describes Special Relativity when rigid material bodies are introduced describing the reality of body contraction; it shows the relevance of acceleration and the necessary evolution of the theoretical framework when acceleration is critical. This book also presents the evolving views of Einstein about the aether. In addition to a careful and elementary introduction to relativity complete with exercises, worked examples and many discussions, this volume connects to current research topics so that readers can explore Special Relativity fr...

Accelerated DNA Methylation Age: Associations with PTSD and Neural Integrity

Science.gov (United States)

Wolf, Erika J.; Logue, Mark W.; Hayes, Jasmeet P.; Sadeh, Naomi; Schichman, Steven A.; Stone, Annjanette; Salat, David H.; Milberg, William; McGlinchey, Regina; Miller, Mark W.

2015-01-01

Background Accumulating evidence suggests that post traumatic stress disorder (PTSD) may accelerate cellular aging and lead to premature morbidity and neurocognitive decline. Methods This study evaluated associations between PTSD and DNA methylation (DNAm) age using recently developed algorithms of cellular age by Horvath (2013) and Hannum et al. (2013). These estimates reflect accelerated aging when they exceed chronological age. We also examined if accelerated cellular age manifested in degraded neural integrity, indexed via diffusion tensor imaging. Results Among 281 male and female veterans of the conflicts in Iraq and Afghanistan, DNAm age was strongly related to chronological age (rs ~.88). Lifetime PTSD severity was associated with Hannum DNAm age estimates residualized for chronological age (β = .13, p= .032). Advanced DNAm age was associated with reduced integrity in the genu of the corpus callosum (β = −.17, p= .009) and indirectly linked to poorer working memory performance via this region (indirect β = − .05, p= .029). Horvath DNAm age estimates were not associated with PTSD or neural integrity. Conclusions Results provide novel support for PTSD-related accelerated aging in DNAm and extend the evidence base of known DNAm age correlates to the domains of neural integrity and cognition. PMID:26447678

Method and apparatus for accelerating a solid mass

International Nuclear Information System (INIS)

Tidman, D.A.; Goldstein, Y.A.

1984-01-01

An axi-symmetrical projectile, having a mass ranging from fractions of a gram to kilograms, is accelerated to velocities in the range of 10 5 to 10 7 centimeters per second by a propelling force produced by a plasma resulting from electric discharge. The discharge is imploded against the projectile surface so lines of the magnetic fields are approximately azimuthal around the projectile axis. The projectile is tapered so it experiences a net, stable axial accelerating force along the accelerator axis by the combined action of the magnetic field producing radially directed momentum and pressure on the plasma, the interaction of the magnetic field and ions induced by the plasma on the surface, as well as material the plasma ablates from the surface. The plasma discharge is initiated either in low density background gas between anode and cathode of a discharge module, or along an insulator surface between the electrodes in low density background gas. Alternatively, in either of these situations the discharge can be initiated in a gas which is produced by ablation of the projectile surface. In an alternative situation, the projectile acts as a switch for triggering discharges. Eddy current heating of the projectile is minimized by shaping the discharge current pulse so the plasma has a relatively weak magnetic field when it arrives at the surface, or by making the projectile electrically non-conducting. To provide a long acceleration path, a series of modules is aligned. In one embodiment, the projectile position, as it advances between modules, is sensed and discharges are switched on sequentially in the modules

Acceleration of 14C beams in electrostatic accelerators

International Nuclear Information System (INIS)

Rowton, L.J.; Tesmer, J.R.

1981-01-01

Operational problems in the production and acceleration of 14 C beams for nuclear structure research in Los Alamos National Laboratory's Van de Graaff accelerators are discussed. Methods for the control of contamination in ion sources, accelerators and personnel are described. Sputter source target fabrication techniques and the relative beam production efficiencies of various types of bound particulate carbon sputter source targets are presented

Absolute calibration and beam background of the Squid Polarimeter

International Nuclear Information System (INIS)

Blaskiewicz, M.M.; Cameron, P.R.; Shea, T.J.

1996-01-01

The problem of beam background in Squid Polarimetry is not without residual benefits. The authors may deliberately generate beam background by gently kicking the beam at the spin tune frequency. This signal may be used to accomplish a simple and accurate absolute calibration of the polarimeter. The authors present details of beam background calculations and their application to polarimeter calibration, and suggest a simple proof-of-principle accelerator experiment

Theoretical implications of the galactic radial acceleration relation of McGaugh, Lelli, and Schombert

Science.gov (United States)

Nesbet, Robert K.

2018-05-01

Velocities in stable circular orbits about galaxies, a measure of centripetal gravitation, exceed the expected Kepler/Newton velocity as orbital radius increases. Standard Λ cold dark matter (ΛCDM) attributes this anomaly to galactic dark matter. McGaugh et al. have recently shown for 153 disc galaxies that observed radial acceleration is an apparently universal function of classical acceleration computed for observed galactic baryonic mass density. This is consistent with the empirical modified Newtonian dynamics (MOND) model, not requiring dark matter. It is shown here that suitably constrained ΛCDM and conformal gravity (CG) also produce such a universal correlation function. ΛCDM requires a very specific dark matter distribution, while the implied CG non-classical acceleration must be independent of galactic mass. All three constrained radial acceleration functions agree with the empirical baryonic v4 Tully-Fisher relation. Accurate rotation data in the nominally flat velocity range could distinguish between MOND, ΛCDM, and CG.

A smoking-related background helps moderate smokers to focus: An event-related potential study using a Go-NoGo task.

Science.gov (United States)

Detandt, Sandrine; Bazan, Ariane; Schröder, Elisa; Olyff, Giulia; Kajosch, Hendrik; Verbanck, Paul; Campanella, Salvatore

2017-10-01

Cognitive impairment is a major component in addiction. However, research has been inconclusive as to whether this is also the case for smokers. The present study aims at providing electrophysiological clue for altered inhibitory control in smokers and at investigating whether reduced inhibition was more pronounced during exposure to a smoking cue. ERPs were recorded during a visual Go-NoGo task performed by 18 smokers and 23 controls, in which either a frequent Go signal (letter "M") or a rare No-Go signal ("letter W") were superimposed on three different long-lasting background contexts: black-neutral, smoking-related and non smoking-related. (1) Smokers performed worse and had an earlier NoGo-N2 latency as compared to controls and independently of context, suggesting a general inhibition impairment; (2) with smoking-related backgrounds specifically, smokers made fewer mistakes than they did in other contexts and displayed a larger NoGo P3 amplitude. These data might suggest that background cues related to addiction may help smokers to be more accurate in an inhibition task. Our results show the classical inhibitory impairment in smokers as compared to non-smokers. However, our data also suggest that a smoking-related background may bolster the inhibitory ability of smokers specifically. Copyright © 2017 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

Plasma-focused cyclic accelerators

International Nuclear Information System (INIS)

Mondelli, A.A.; Chernin, D.P.

1985-01-01

The use of ambient plasma to neutralize the transverse forces of an intense particle beam has been known for many years. Most recently, the so-called ion-focused regime (IFR) for beam propagation has been used as a means of focusing intense electron beams in linear accelerators and suggested for injecting an electron beam across magnetic field lines into a high-current cyclic accelerator. One technique for generating the required background plasma for IFR propagation is to use a laser to ionize ambient gas in the accelerator chamber. For cyclic accelerators a technique is required for carrying the plasma channel and the beam around a bend. Multiple laser-generated channels with dipole magnetic fields to switch the beam from one channel to the next have been tested at Sandia. This paper discusses an alternative means of plasma production for IFR, viz. by using rf breakdown. For this approach the accelerator chamber acts as a waveguide. With a suitable driving frequency, a waveguide mode can be driven which has its peak field intensity on the axis with negligible fields at the chamber walls. The plasma production and hence the beam propagation is thereby isolated from the walls. This technique is not limited to toroidal accelerators. It may be applied to any accelerator or recirculator geometry as well as for beam steering and for injection or extraction of beams in closed accelerator configurations

Dusty Cloud Acceleration by Radiation Pressure in Rapidly Star-forming Galaxies

Science.gov (United States)

Zhang, Dong; Davis, Shane W.; Jiang, Yan-Fei; Stone, James M.

2018-02-01

We perform two-dimensional and three-dimensional radiation hydrodynamic simulations to study cold clouds accelerated by radiation pressure on dust in the environment of rapidly star-forming galaxies dominated by infrared flux. We utilize the reduced speed of light approximation to solve the frequency-averaged, time-dependent radiative transfer equation. We find that radiation pressure is capable of accelerating the clouds to hundreds of kilometers per second while remaining dense and cold, consistent with observations. We compare these results to simulations where acceleration is provided by entrainment in a hot wind, where the momentum injection of the hot flow is comparable to the momentum in the radiation field. We find that the survival time of the cloud accelerated by the radiation field is significantly longer than that of a cloud entrained in a hot outflow. We show that the dynamics of the irradiated cloud depends on the initial optical depth, temperature of the cloud, and intensity of the flux. Additionally, gas pressure from the background may limit cloud acceleration if the density ratio between the cloud and background is ≲ {10}2. In general, a 10 pc-scale optically thin cloud forms a pancake structure elongated perpendicular to the direction of motion, while optically thick clouds form a filamentary structure elongated parallel to the direction of motion. The details of accelerated cloud morphology and geometry can also be affected by other factors, such as the cloud lengthscale, reduced speed of light approximation, spatial resolution, initial cloud structure, and dimensionality of the run, but these have relatively little affect on the cloud velocity or survival time.

Historical Background of Turkey-Syria Relations in the Term of Social Geograpy

Directory of Open Access Journals (Sweden)

Sedat BENEK

2016-06-01

Full Text Available Historical process between Syria and Turkey has always high tension. According to Turkey, Syria is the country,which has hosted the Turkish enemies, which causes problems in the sharing of water resources and geographically it is seen as ‘’enemy country’’ because of interfering in Turkey's territorial integrity; According to Syria, Turkey is "enemy" is because it doesn’t share water resources in a fair way and as supporters of western countries, claiming rights over their territory (Hatay. In short, for many years strained relations with Syria-Turkey relations , by signing of the Treaty of Adana in 1998, good relations has been established with unpredictable speed in a short time . Escalating positive relations between Turkey and Syria in the years 1998-2011, and relations has again strained the outbreak of the Syria Civil War in 2011, and was even worse off period before 1998. Therefore the main goal of this study "Historical Background of Turkey-Syria Relations in terms of Social Geography" is to examine the dynamics of it. For this purpose, treaties defining the Turkey-Syria relationship, the protocols, briefings given by officials were examined. Historical background of the two countries' relations in terms of social geography has been tried to put forward in chronological order

The relation between tilt table and acceleration-tolerance and their dependence on stature and physical fitness

Science.gov (United States)

Klein, K. E.; Backhausen, F.; Bruner, H.; Eichhorn, J.; Jovy, D.; Schotte, J.; Vogt, L.; Wegman, H. M.

1980-01-01

A group of 12 highly trained athletes and a group of 12untrained students were subjected to passive changes of position on a tilt table and positive accelerations in a centrifuge. During a 20 min tilt, including two additional respiratory maneuvers, the number of faints and average cardiovascular responses did not differ significantly between the groups. During linear increase of acceleration, the average blackout level was almost identical in both groups. Statistically significant coefficients of product-moment correlation for various relations were obtained. The coefficient of multiple determination computed for the dependence of acceleration tolerance on heart-eye distance and systolic blood pressure at rest allows the explanation of almost 50% of the variation of acceleration tolerance. The maximum oxygen uptake showed the expected significant correlation to the heart rate at rest, but not the acceleration tolerance, or to the cardiovascular responses to tilting.

Clock hypothesis of relativity theory, maximal acceleration, and Mössbauer spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Potzel, W., E-mail: wpotzel@ph.tum.de [Technische Universität München, Physik-Department E15 (Germany)

2016-12-15

Results obtained several years ago using the high-resolution 93.3 keV Mössbauer resonance in {sup 67}ZnO and β{sup ′}-brass have been reanalyzed with the notion that the clock hypothesis of Special Relativity Theory is not sufficient, but that a maximal acceleration a{sub m} exists and that an acceleration a contributes to the temperature dependence of the center shift by a term ±(1/2)(a/a{sub m}){sup 2}. The significance of the sign of this term is discussed in detail. For both substances a lower limit of a{sub m}>1.5⋅10{sup 21}m/s {sup 2} is inferred which is more than two orders of magnitude larger than - and thus excludes - the value a{sub m}=1⋅10{sup 19}m/s {sup 2} suggested by {sup 57}Fe rotor experiments.

Scaling relations for plasma production and acceleration of rotating plasma flows

International Nuclear Information System (INIS)

Ikehata, Takashi; Tanabe, Toshio; Mase, Hiroshi; Sekine, Ryusuke; Hasegawa, Kazuyuki.

1989-01-01

Scaling relations are investigated theoretically and experimentally of the plasma production and acceleration in the rotating plasma gun which has been developed as a new means of plasma centrifuge. Two operational modes: the gas-discharge mode for gaseous elements and the vacuum-discharge mode for solid elements are studied. Relations of the plasma density and velocities to the discharge current and the magnetic field are derived. The agreement between experiment and theory is quite well. It is found that fully-ionized rotating plasmas produced in the gas-discharge mode is most advantageous to realize efficient plasma centrifuge. (author)

Superconductivity and future accelerators

International Nuclear Information System (INIS)

Danby, G.T.; Jackson, J.W.

1963-01-01

For 50 years particle accelerators employing accelerating cavities and deflecting magnets have been developed at a prodigious rate. New accelerator concepts and hardware ensembles have yielded great improvements in performance and GeV/$. The great idea for collective acceleration resulting from intense auxiliary charged-particle beams or laser light may or may not be just around the corner. In its absence, superconductivity (SC) applied both to rf cavities and to magnets opened up the potential for very large accelerators without excessive energy consumption and with other economies, even with the cw operation desirable for colliding beams. HEP has aggressively pioneered this new technology: the Fermilab single ring 1 TeV accelerator - 2 TeV collider is near the testing stage. Brookhaven National Laboratory's high luminosity pp 2 ring 800 GeV CBA collider is well into construction. Other types of superconducting projects are in the planning stage with much background R and D accomplished. The next generation of hadron colliders under discussion involves perhaps a 20 TeV ring (or rings) with 40 TeV CM energy. This is a very large machine: even if the highest practical field B approx. 10T is used, the radius is 10x that of the Fermilab accelerator. An extreme effort to get maximum GeV/$ may be crucial even for serious consideration of funding

Accelerator mass spectrometry of 41Ca with a positive-ion source and the UNILAC accelerator

International Nuclear Information System (INIS)

Steinhof, A.; Henning, W.; Mueller, M.; Roeckl, E.; Schuell, D.; Korschinek, G.; Nolte, E.; Paul, M.

1987-06-01

We have made first tests investigating the performance characteristics of the UNILAC accelerator system at GSI, in order to explore the sensitivity achievable in accelerator mass spectrometry (AMS) of 41 Ca with high-current positive-ion sources. Positively charged Ca 3+ ions of up to about 100 micro-amperes electrical current were injected from a penning-sputter source and, after further stripping to Ca 9+ , accelerated to 14.3 MeV/nucleon. The combination of velocity-focussing accelerator and magnetic ion-beam transport system completely eliminated background from the other calcium isotopes. Full-stripping and detection of 41 Ca 20+ ions with a magnetic spectrograph provides separation from isobaric 41 K and, at present, a level of sensitivity of 41 Ca/Ca ≅ 2x10 -15 . Future improvements and implications for dating of Pleistoscene samples will be discussed. (orig.)

Acceleration of black hole universe

Science.gov (United States)

Zhang, T. X.; Frederick, C.

2014-01-01

Recently, Zhang slightly modified the standard big bang theory and developed a new cosmological model called black hole universe, which is consistent with Mach's principle, governed by Einstein's general theory of relativity, and able to explain all observations of the universe. Previous studies accounted for the origin, structure, evolution, expansion, and cosmic microwave background radiation of the black hole universe, which grew from a star-like black hole with several solar masses through a supermassive black hole with billions of solar masses to the present state with hundred billion-trillions of solar masses by accreting ambient matter and merging with other black holes. This paper investigates acceleration of the black hole universe and provides an alternative explanation for the redshift and luminosity distance measurements of type Ia supernovae. The results indicate that the black hole universe accelerates its expansion when it accretes the ambient matter in an increasing rate. In other words, i.e., when the second-order derivative of the mass of the black hole universe with respect to the time is positive . For a constant deceleration parameter , we can perfectly explain the type Ia supernova measurements with the reduced chi-square to be very close to unity, χ red˜1.0012. The expansion and acceleration of black hole universe are driven by external energy.

CERN-derived analysis of lunar radiation backgrounds

Science.gov (United States)

Wilson, Thomas L.; Svoboda, Robert

1993-01-01

The Moon produces radiation which background-limits scientific experiments there. Early analyses of these backgrounds have either failed to take into consideration the effect of charm in particle physics (because they pre-dated its discovery), or have used branching ratios which are no longer strictly valid (due to new accelerator data). We are presently investigating an analytical program for deriving muon and neutrino spectra generated by the Moon, converting an existing CERN computer program known as GEANT which does the same for the Earth. In so doing, this will (1) determine an accurate prompt neutrino spectrum produced by the lunar surface; (2) determine the lunar subsurface particle flux; (3) determine the consequence of charm production physics upon the lunar background radiation environment; and (4) provide an analytical tool for the NASA astrophysics community with which to begin an assessment of the Moon as a scientific laboratory versus its particle radiation environment. This will be done on a recurring basis with the latest experimental results of the particle data groups at Earth-based high-energy accelerators, in particular with the latest branching ratios for charmed meson decay. This will be accomplished for the first time as a full 3-dimensional simulation.

The impact of musicianship on the cortical mechanisms related to separating speech from background noise.

Science.gov (United States)

Zendel, Benjamin Rich; Tremblay, Charles-David; Belleville, Sylvie; Peretz, Isabelle

2015-05-01

Musicians have enhanced auditory processing abilities. In some studies, these abilities are paralleled by an improved understanding of speech in noisy environments, partially due to more robust encoding of speech signals in noise at the level of the brainstem. Little is known about the impact of musicianship on attention-dependent cortical activity related to lexical access during a speech-in-noise task. To address this issue, we presented musicians and nonmusicians with single words mixed with three levels of background noise, across two conditions, while monitoring electrical brain activity. In the active condition, listeners repeated the words aloud, and in the passive condition, they ignored the words and watched a silent film. When background noise was most intense, musicians repeated more words correctly compared with nonmusicians. Auditory evoked responses were attenuated and delayed with the addition of background noise. In musicians, P1 amplitude was marginally enhanced during active listening and was related to task performance in the most difficult listening condition. By comparing ERPs from the active and passive conditions, we isolated an N400 related to lexical access. The amplitude of the N400 was not influenced by the level of background noise in musicians, whereas N400 amplitude increased with the level of background noise in nonmusicians. In nonmusicians, the increase in N400 amplitude was related to a reduction in task performance. In musicians only, there was a rightward shift of the sources contributing to the N400 as the level of background noise increased. This pattern of results supports the hypothesis that encoding of speech in noise is more robust in musicians and suggests that this facilitates lexical access. Moreover, the shift in sources suggests that musicians, to a greater extent than nonmusicians, may increasingly rely on acoustic cues to understand speech in noise.

On the Phenomenology of an Accelerated Large-Scale Universe

Directory of Open Access Journals (Sweden)

Martiros Khurshudyan

2016-10-01

Full Text Available In this review paper, several new results towards the explanation of the accelerated expansion of the large-scale universe is discussed. On the other hand, inflation is the early-time accelerated era and the universe is symmetric in the sense of accelerated expansion. The accelerated expansion of is one of the long standing problems in modern cosmology, and physics in general. There are several well defined approaches to solve this problem. One of them is an assumption concerning the existence of dark energy in recent universe. It is believed that dark energy is responsible for antigravity, while dark matter has gravitational nature and is responsible, in general, for structure formation. A different approach is an appropriate modification of general relativity including, for instance, f ( R and f ( T theories of gravity. On the other hand, attempts to build theories of quantum gravity and assumptions about existence of extra dimensions, possible variability of the gravitational constant and the speed of the light (among others, provide interesting modifications of general relativity applicable to problems of modern cosmology, too. In particular, here two groups of cosmological models are discussed. In the first group the problem of the accelerated expansion of large-scale universe is discussed involving a new idea, named the varying ghost dark energy. On the other hand, the second group contains cosmological models addressed to the same problem involving either new parameterizations of the equation of state parameter of dark energy (like varying polytropic gas, or nonlinear interactions between dark energy and dark matter. Moreover, for cosmological models involving varying ghost dark energy, massless particle creation in appropriate radiation dominated universe (when the background dynamics is due to general relativity is demonstrated as well. Exploring the nature of the accelerated expansion of the large-scale universe involving generalized

Modulation of accelerated repopulation in mouse skin during daily irradiation

International Nuclear Information System (INIS)

Trott, K.-R.; Shirazi, A.; Heasman, F.

1999-01-01

Background and purpose: The timing of acceleration of repopulation in the epidermis during daily irradiation is related to the development of skin erythema and epidermal hypoplasia. Therefore, the relationship between impairment of the epidermal barrier function, the dermal inflammatory response and epidermal hypoplasia with the acceleration of repopulation was investigated.Materials and purpose: Skin fields of approximately 1 cm 2 on the thighs of TUC mice were given five daily fractions of 3 Gy in each week followed by top-up doses at the end of the first, the second, or the third week to determine residual epidermal tolerance and to calculate repopulation rates in weeks 1, 2, or 3. Systemic modulation of repopulation was attempted by daily indomethacine during fractionated irradiation whereas tape stripping or UV-B exposure before the start of fractionated irradiation attempted local modulation. In parallel experiments, the water permeability coefficient of the epidermis was determined ex vivo by studying transepidermal transport of tritiated water.Results: Without modulation, no repopulation was found in the first week of daily fractionation but repopulation compensated 30% of the dose given in week two and 70% of the dose given in week three. Only tape stripping before the start of fractionated irradiation accelerated repopulation in week one. UV-B had no effect on repopulation although it stimulated proliferation as much as tape stripping. Indomethacin did not suppress acceleration of repopulation. A significant increase in transepidermal water loss was found but only after repopulation had already accelerated.Conclusions: Acceleration of repopulation in mouse epidermis during daily-fractionated irradiation is not related to the simultaneous development of an inflammatory response. Also, the loss of the epidermal barrier function is not involved in the development of the acceleration response, which rather seems to be triggered directly by the decreased

Accelerated ion beam research at ATOMKI

International Nuclear Information System (INIS)

Kiss, A.Z.

2009-01-01

The paper summarizes the studies on accelerated ion beams at ATOMKI and their technical background, their use from chemical analysis to biological, medical, geological, archaeological applications, their advance from material science to micromachining. (TRA)

Proceedings, CAS - CERN Accelerator School: RF for Accelerators, Ebeltoft, Denmark, 8 - 17 Jun 2010

CERN Document Server

Bailey, R

2012-01-01

These proceedings present the lectures given at the twenty-fourth specialized course organized by the CERN Accelerator School (CAS). The course was held in Ebeltoft, Denmark, from 8-17 June, 2010 in collaboration with Aarhus University, with the topic 'RF for Accelerators' While this topic has been covered by CAS previously, early in the 1990s and again in 2000, it was recognized that recent advances in the field warranted an updated course. Following introductory courses covering the background physics, the course attempted to cover all aspects of RF for accelerators; from RF power generation and transport, through cavity and coupler design, electronics and low level control, to beam diagnostics and RF gymnastics. The lectures were supplemented with several sessions of exercises, which were completed by discussion sessions on the solutions.

CAS Accelerator Physics (Ion Sources) in Slovakia

CERN Multimedia

CAS School

2012-01-01

The CERN Accelerator School (CAS) and the Slovak University of Technology jointly organised a specialised course on ion sources, held at the Hotel Senec, Senec, Slovakia, from 29 May to 8 June, 2012.   Following some background lectures on accelerator physics and the fundamental processes of atomic and plasma physics, the course covered a wide range of topics related to ion sources and highlighted the latest developments in the field. Realistic case studies and topical seminars completed the programme. The school was very successful, with 69 participants representing 25 nationalities. Feedback from the participants was extremely positive, reflecting the high standard of the lectures. The case studies were performed with great enthusiasm and produced some excellent results. In addition to the academic programme, the participants were able to take part in a one-day excursion consisting of a guided tour of Bratislava and free time. A welcome event was held at the Hotel Senec, with s...

New scheme for the design and operation of proton--proton storage accelerators

International Nuclear Information System (INIS)

Claus, J.; Herrera, J.; Humphrey, J.; Marx, M.; Month, M.

1977-01-01

A new system is presented for storage accelerating rings which allows many options for operation. During injection, acceleration, and collision, the beams are maintained in the form of azimuthally long bunches. Current is built up in a low-energy, small circumference accumulator ring. Injection into the storage accelerators is carried out with the bunches phased so that they do not collide. The rf buckets can be matched to the incoming long bunches with only a small dilution. Operation of the storage rings consists of: (1) accelerating the formed bunches to any desired energy; and (2) bringing the bunches into collision by relative phasing of the rf in the two rings. This system provides considerable simplification in the design and operation of high energy p-p facilities. For example, it reduces the beam stacking time, relaxes the impedance tolerances relating to longitudinal stability, reduces the aperture utilization, and avoids radiation background problems associated with beam manipulations. A prototype design is considered, using as a basis the parameters of the ISABELLE facility. Performance characteristics and operational procedures are presented. The many advantages related to the machine and experimental aspects are discussed. In particular, cycling the energy during collisions is an interesting option. Lastly, the significance of extending such a facility to higher energy p-p collisions is outlined

Some additional results on the directional relationships between forces and accelerations in special relativity

International Nuclear Information System (INIS)

Gonzalez-Diaz, P.F.

1979-01-01

Some directional relationships between forces and accelerations in special relativity have been studied by considering the most general case of a body having x, y and z components of velocity, which is acted upon by a force with nonzero components. The behaviour of asub(y)/asub(x) and asub(y)/asub(z) vs. velocity for different force component ratios is studied in the general situation in which vsub(x) is unequal to vsub(y) is unequal to vsub(z). It is shown that one or two, suddenly varying, negative acceleration components can result for the body at sufficiently high velocities, and an explanation is given. (author)

Some additional results on the directional relationships between forces and accelerations in special relativity

International Nuclear Information System (INIS)

Gonzales-Diaz, P.F.

1979-01-01

Some directional relationships between forces and accelerations in special relativity have been studied by considering the most general case of a body having x, y and z components of velocity, which is acted upon by a force with nonzero components. The behaviour of a sub(y)/ a sub(x) and a sub(y)/ a sub(z) vs. velocity for different force component ratios is studied in the general situation in which vsub(x) different from Vsub(y)different from vsub(z). It is shown that one or two, suddently varying, negative acceleration components can result for the body at sufficiently high velocities, and an explanation is given

CEPC-SPPC accelerator status towards CDR

Science.gov (United States)

Gao, J.

2017-12-01

In this paper we will give an introduction to the Circular Electron Positron Collider (CEPC). The scientific background, physics goal, the collider design requirements and the conceptual design principle of the CEPC are described. On the CEPC accelerator, the optimization of parameter designs for the CEPC with different energies, machine lengths, single ring and crab-waist collision partial double ring, advanced partial double ring and fully partial double ring options, etc. have been discussed systematically, and compared. The CEPC accelerator baseline and alternative designs have been proposed based on the luminosity potential in relation with the design goals. The CEPC sub-systems, such as the collider main ring, booster, electron positron injector, etc. have also been introduced. The detector and the MAchine-Detector Interface (MDI) design have been briefly mentioned. Finally, the optimization design of the Super Proton-Proton Collider (SppC), its energy and luminosity potentials, in the same tunnel of the CEPC are also discussed. The CEPC-SppC Progress Report (2015-2016) has been published.

Radon-related Backgrounds in the LUX Dark Matter Search

Science.gov (United States)

Bradley, A.; Akerib, D. S.; Araújo, H. M.; Bai, X.; Bailey, A. J.; Balajthy, J.; Bernard, E.; Bernstein, A.; Byram, D.; Cahn, S. B.; Carmona-Benitez, M. C.; Chan, C.; Chapman, J. J.; Chiller, A. A.; Chiller, C.; Coffey, T.; Currie, A.; de Viveiros, L.; Dobi, A.; Dobson, J.; Druszkiewicz, E.; Edwards, B.; Faham, C. H.; Fiorucci, S.; Flores, C.; Gaitskell, R. J.; Gehman, V. M.; Ghag, C.; Gibson, K. R.; Gilchriese, M. G. D.; Hall, C.; Hertel, S. A.; Horn, M.; Huang, D. Q.; Ihm, M.; Jacobsen, R. G.; Kazkaz, K.; Knoche, R.; Larsen, N. A.; Lee, C.; Lindote, A.; Lopes, M. I.; Malling, D. C.; Mannino, R.; McKinsey, D. N.; Mei, D.-M.; Mock, J.; Moongweluwan, M.; Morad, J.; Murphy, A. St. J.; Nehrkorn, C.; Nelson, H.; Neves, F.; Ott, R. A.; Pangilinan, M.; Parker, P. D.; Pease, E. K.; Pech, K.; Phelps, P.; Reichhart, L.; Shutt, T.; Silva, C.; Solovov, V. N.; Sorensen, P.; O'Sullivan, K.; Sumner, T. J.; Szydagis, M.; Taylor, D.; Tennyson, B.; Tiedt, D. R.; Tripathi, M.; Uvarov, S.; Verbus, J. R.; Walsh, N.; Webb, R.; White, J. T.; Witherell, M. S.; Wolfs, F. L. H.; Woods, M.; Zhang, C.

The LUX detector is currently in operation at the Davis Campus at the 4850' level of the Sanford Underground Research Facility (SURF) in Lead, SD to directly search for WIMP dark matter. Knowing the type and rate of backgrounds is critical in a rare, low energy event search, and LUX was designed, constructed, and deployed to mitigate backgrounds, both internal and external. An important internal background are decays of radon and its daughters. These consist of alpha decays, which are easily tagged and are a tracer of certain backgrounds, and beta decays, some of which are not as readily tagged and present a background for the WIMP search. We report on studies of alpha decay and discuss implications for the WIMP search.

Machine Induced Experimental Background Conditions in the LHC

CERN Document Server

Levinsen, Yngve Inntjore; Stapnes, Steinar

2012-09-19

The Large Hadron Collider set a new energy record for particle accelerators in late 2009, breaking the previous record held by Tevatron of 2 TeV collision energy. The LHC today operates at a collision energy of 7 TeV. With higher beam energy and intensity, measures have to be taken to ensure optimal experimental conditions and safety of the machine and detectors. Machine induced experimental background can severely reduce the quality of experimental triggers and track reconstruction. In a worst case, the radiation levels can be damaging for some of the subdetectors. The LHC is a particular challenge in this regard due to the vastly different operating conditions of the different experiments. The nominal luminosity varies by four orders of magnitude. The unprecedented stored beam energy and the amount of superconducting elements can make it challenging to protect the accelerator itself as well. In this work we have simulated and measured the machine induced background originating from various sources: the beam...

Collective ion acceleration by relativistic electron beams in plasmas

International Nuclear Information System (INIS)

Galvez, M.; Gisler, G.

1991-01-01

A two-dimensional fully electromagnetic particle-in-cell code is used to simulate the interaction of a relativistic electron beam injected into a finite-size background neutral plasma. The simulations show that the background electrons are pushed away from the beam path, forming a neutralizing ion channel. Soon after the beam head leaves the plasma, a virtual cathode forms which travels away with the beam. However, at later times a second, quasi-stationary, virtual cathode forms. Its position and strength depends critically on the parameters of the system which critically determines the efficiency of the ion acceleration process. The background ions trapped in the electrostatic well of the virtual cathode are accelerated and at later times, the ions as well as the virtual cathode drift away from the plasma region. The surfing of the ions in the electrostatic well produces an ion population with energies several times the initial electron beam energy. It is found that optimum ion acceleration occurs when the beam-to-plasma density ratio is near unity. When the plasma is dense, the beam is a weak perturbation and accelerates few ions, while when the plasma is tenuous, the beam is not effectively neutralized, and a virtual cathode occurs right at the injection plane. The simulations also show that, at the virtual cathode position, the electron beam is pinched producing a self-focusing phenomena

Measured Radiation and Background Levels During Transmission of Megawatt Electron Beams Through Millimeter Apertures

Energy Technology Data Exchange (ETDEWEB)

Alarcon, Ricardo [Arizona State University, Glendale, AZ (United States); Balascuta, S. [Arizona State University, Glendale, AZ (United States); Benson, Stephen V. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Bertozzi, William [Massachusetts Institute of Technology, Cambridge, MA (United States); Boyce, James R. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Cowan, Ray [Massachusetts Institute of Technology, Cambridge, MA (United States); Douglas, David R. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Evtushenko, Pavel [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Fisher, P. [Massachusetts Institute of Technology, Cambridge, MA (United States); Ihloff, Ernest E. [Hampton University, Hampton, VA (United States); Kalantarians, Narbe [Hampton University, Hampton, VA (United States); Kelleher, Aidan Michael [Massachusetts Institute of Technology, Cambridge, MA (United States); Krossler, W. J. [William and Mary College, Williamsburg, VA (United States); Legg, Robert A. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Long, Elena [University of New Hampshire, Durham, NH (United States); Milner, Richard [Massachusetts Institute of Technology, Cambridge, MA (United States); Neil, George R. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Ou, Longwu [Massachusetts Institute of Technology, Cambridge, MA (United States); Schmookler, Barack Abraham [Massachusetts Institute of Technology, Cambridge, MA (United States); Tennant, Christopher D. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Tschalar, C. [Massachusetts Institute of Technology, Cambridge, MA (United States); Williams, Gwyn P. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Zhang, Shukui [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)

2013-11-01

We report measurements of photon and neutron radiation levels observed while transmitting a 0.43 MW electron beam through millimeter-sized apertures and during beam-off, but accelerating gradient RF-on, operation. These measurements were conducted at the Free-Electron Laser (FEL) facility of the Jefferson National Accelerator Laboratory (JLab) using a 100 MeV electron beam from an energy-recovery linear accelerator. The beam was directed successively through 6 mm, 4 mm, and 2 mm diameter apertures of length 127 mm in aluminum at a maximum current of 4.3 mA (430 kW beam power). This study was conducted to characterize radiation levels for experiments that need to operate in this environment, such as the proposed DarkLight Experiment. We find that sustained transmission of a 430 kW continuous-wave (CW) beam through a 2 mm aperture is feasible with manageable beam-related backgrounds. We also find that during beam-off, RF-on operation, multipactoring inside the niobium cavities of the accelerator cryomodules is the primary source of ambient radiation when the machine is tuned for 130 MeV operation.

Accelerating Inspire

CERN Document Server

AUTHOR|(CDS)2266999

2017-01-01

CERN has been involved in the dissemination of scientific results since its early days and has continuously updated the distribution channels. Currently, Inspire hosts catalogues of articles, authors, institutions, conferences, jobs, experiments, journals and more. Successful orientation among this amount of data requires comprehensive linking between the content. Inspire has lacked a system for linking experiments and articles together based on which accelerator they were conducted at. The purpose of this project has been to create such a system. Records for 156 accelerators were created and all 2913 experiments on Inspire were given corresponding MARC tags. Records of 18404 accelerator physics related bibliographic entries were also tagged with corresponding accelerator tags. Finally, as a part of the endeavour to broaden CERN's presence on Wikipedia, existing Wikipedia articles of accelerators were updated with short descriptions and links to Inspire. In total, 86 Wikipedia articles were updated. This repo...

Social-emotional characteristics of gifted accelerated and non-accelerated students in the Netherlands.

Science.gov (United States)

Hoogeveen, Lianne; van Hell, Janet G; Verhoeven, Ludo

2012-12-01

In the studies of acceleration conducted so far a multidimensional perspective has largely been neglected. No attempt has been made to relate social-emotional characteristics of accelerated versus non-accelerated students in perspective of environmental factors. In this study, social-emotional characteristics of accelerated gifted students in the Netherlands were examined in relation to personal and environmental factors. Self-concept and social contacts of accelerated (n = 148) and non-accelerated (n = 55) gifted students, aged 4 to 27 (M = 11.22, SD = 4.27) were measured. Self-concept and social contacts of accelerated and non-accelerated gifted students were measured using a questionnaire and a diary, and parents of these students evaluated their behavioural characteristics. Gender and birth order were studied as personal factors and grade, classroom, teachers' gender, teaching experience, and the quality of parent-school contact as environmental factors. The results showed minimal differences in the social-emotional characteristics of accelerated and non-accelerated gifted students. The few differences we found favoured the accelerated students. We also found that multiple grade skipping does not have negative effects on social-emotional characteristics, and that long-term effects of acceleration tend to be positive. As regards the possible modulation of personal and environmental factors, we merely found an impact of such factors in the non-accelerated group. The results of this study strongly suggest that social-emotional characteristics of accelerated gifted students and non-accelerated gifted students are largely similar. These results thus do not support worries expressed by teachers about the acceleration of gifted students. Our findings parallel the outcomes of earlier studies in the United States and Germany in that we observed that acceleration does not harm gifted students, not even in the case of multiple grade skipping. On the contrary, there is a

Accelerating Value Creation with Accelerators

DEFF Research Database (Denmark)

Jonsson, Eythor Ivar

2015-01-01

and developing the best business ideas and support the due diligence process. Even universities are noticing that the learning experience of the action learning approach is an effective way to develop capabilities and change cultures. Accelerators related to what has historically been associated...

Accelerators for energy

International Nuclear Information System (INIS)

Inoue, Makoto

2000-01-01

A particle accelerator is a device to consume energy but not to produce it. Then, the titled accelerator seems to mean an accelerator for using devices related to nuclear energy. For an accelerator combined to nuclear fissionable fuel, neutron sources are D-T type, (gamma, n) reaction using electron beam type spallation type, and so forth. At viewpoints of powers of incident beam and formed neutron, a spallation type source using high energy proton is told to be effective but others have some advantages by investigation on easy operability, easy construction, combustion with target, energy and directivity of neutron, and so forth. Here were discussed on an accelerator for research on accelerator driven energy system by dividing its researching steps, and on kind, energy, beam intensity, and so forth of an accelerator suitable for it. And, space electric charge effect at beam propagation direction controlled by beam intensity of cyclotron was also commented. (G.K.)

Relativity in modern physics

CERN Document Server

Deruelle, Nathalie

2018-01-01

This comprehensive textbook on relativity integrates Newtonian physics, special relativity and general relativity into a single book that emphasizes the deep underlying principles common to them all, yet explains how they are applied in different ways in these three contexts. Newton's ideas about how to represent space and time, his laws of dynamics, and his theory of gravitation established the conceptual foundation from which modern physics developed. Book I in this volume offers undergraduates a modern view of Newtonian theory, emphasizing those aspects needed for understanding quantum and relativistic contemporary physics. In 1905, Albert Einstein proposed a novel representation of space and time, special relativity. Book II presents relativistic dynamics in inertial and accelerated frames, as well as a detailed overview of Maxwell's theory of electromagnetism. This provides undergraduate and graduate students with the background necessary for studying particle and accelerator physics, astrophysics and ...

Computer-based training for particle accelerator personnel

International Nuclear Information System (INIS)

Silbar, R.R.

1999-01-01

A continuing problem at many laboratories is the training of new operators in the arcane technology of particle accelerators. Presently most of this training occurs on the job, under a mentor. Such training is expensive, and while it provides operational experience, it is frequently lax in providing the physics background needed to truly understand accelerator systems. Using computers in a self-paced, interactive environment can be more effective in meeting this training need. copyright 1999 American Institute of Physics

From Cleanup to Stewardship. A companion report to Accelerating Cleanup: Paths to Closure and background information to support the scoping process required for the 1998 PEIS Settlement Study

Energy Technology Data Exchange (ETDEWEB)

None, None

1999-10-01

Long-term stewardship is expected to be needed at more than 100 DOE sites after DOE's Environmental Management program completes disposal, stabilization, and restoration operations to address waste and contamination resulting from nuclear research and nuclear weapons production conducted over the past 50 years. From Cleanup to stewardship provides background information on the Department of Energy (DOE) long-term stewardship obligations and activities. This document begins to examine the transition from cleanup to long-term stewardship, and it fulfills the Secretary's commitment to the President in the 1999 Performance Agreement to provide a companion report to the Department's Accelerating Cleanup: Paths to Closure report. It also provides background information to support the scoping process required for a study on long-term stewardship required by a 1998 Settlement Agreement.

Accelerated Resolution Therapy for treatment of pain secondary to symptoms of combat-related posttraumatic stress disorder

Directory of Open Access Journals (Sweden)

Kevin E. Kip

2014-05-01

Full Text Available Background: As many as 70% of veterans with chronic pain treated within the US Veterans Administration (VA system may have posttraumatic stress disorder (PTSD, and conversely, up to 80% of those with PTSD may have pain. We describe pain experienced by US service members and veterans with symptoms of PTSD, and report on the effect of Accelerated Resolution Therapy (ART, a new, brief exposure-based therapy, on acute pain reduction secondary to treatment of symptoms of PTSD. Methods: A randomized controlled trial of ART versus an attention control (AC regimen was conducted among 45 US service members/veterans with symptoms of combat-related PTSD. Participants received a mean of 3.7 sessions of ART. Results: Mean age was 41.0 + 12.4 years and 20% were female. Most veterans (93% reported pain. The majority (78% used descriptive terms indicative of neuropathic pain, with 29% reporting symptoms of a concussion or feeling dazed. Mean pre-/post-change on the Pain Outcomes Questionnaire (POQ was −16.9±16.6 in the ART group versus −0.7±14.2 in the AC group (p=0.0006. Among POQ subscales, treatment effects with ART were reported for pain intensity (effect size = 1.81, p=0.006, pain-related impairment in mobility (effect size = 0.69, p=0.01, and negative affect (effect size = 1.01, p=0.001. Conclusions: Veterans with symptoms of combat-related PTSD have a high prevalence of significant pain, including neuropathic pain. Brief treatment of symptoms of combat-related PTSD among veterans by use of ART appears to acutely reduce concomitant pain.

On the mechanism of high-voltage discharge initiation in high-voltage accelerator accelerating tubes

International Nuclear Information System (INIS)

Zheleznikov, F.G.

1983-01-01

Experimental investigation into physical natupe of discharge processes in high-voltage accelerator accelerating tubes in the absence of the accelerated particle beam are conducted. The installation for the study of the mechanism of initiating vacuum isolation conductivity is used in the experiments. The vacuum chamber of the installation is made of steel and sealed with rubber packings. Electrodes 300-360 mm in diameter are made of stainless steel. Two variants of cleaning technology were used before electrode assembling: 1) degreasing by organic solvents; 2) cleaning by fine grinding cloth with successive washing by rectificated alcohol. Analysis of the obtained data shows that forma. tion of background flux of charged particles in interelectrode gap is caused by external photoelectric effect, excited by X radiation, which initiates the formation of intensive internal field in microfilms of non-conducting impurities on the electrode surfaces. The secondary electron emission plays the minor role at that

Cumulative neutrino background from quasar-driven outflows

Energy Technology Data Exchange (ETDEWEB)

Wang, Xiawei; Loeb, Abraham, E-mail: xiawei.wang@cfa.harvard.edu, E-mail: aloeb@cfa.harvard.edu [Department of Astronomy, Harvard University, 60 Garden Street, Cambridge, MA 02138 (United States)

2016-12-01

Quasar-driven outflows naturally account for the missing component of the extragalactic γ-ray background through neutral pion production in interactions between protons accelerated by the forward outflow shock and interstellar protons. We study the simultaneous neutrino emission by the same protons. We adopt outflow parameters that best fit the extragalactic γ-ray background data and derive a cumulative neutrino background of ∼ 10{sup −7} GeV cm{sup −2} s{sup −1} sr{sup −1} at neutrino energies E {sub ν} ∼> 10 TeV, which naturally explains the most recent IceCube data without tuning any free parameters. The link between the γ-ray and neutrino emission from quasar outflows can be used to constrain the high-energy physics of strong shocks at cosmological distances.

Egypt: Background and U.S. Relations

Science.gov (United States)

2009-05-12

contributions from Germany , Japan, and Switzerland. For more information on the MFO, see http://www.mfo.org/Default.asp?bhcp=1. Egypt: Background and...2008 Report, Egypt’s pace of business reforms and deregulation between 2006 and 2007 ranked first worldwide. In recent years, the state has...reinvigorated its privatization program by divesting shares in the state-dominated banking and insurance sectors. Additionally, the government removed import

Pair creation of higher dimensional black holes on a de Sitter background

International Nuclear Information System (INIS)

Dias, Oscar J.C.; Lemos, Jose P.S.

2004-01-01

We study in detail the quantum process in which a pair of black holes is created in a higher D-dimensional de Sitter (dS) background. The energy to materialize and accelerate the pair comes from the positive cosmological constant. The instantons that describe the process are obtained from the Tangherlini black hole solutions. Our pair creation rates reduce to the pair creation rate for Reissner-Nordstroem-dS solutions when D=4. Pair creation of black holes in the dS background becomes less suppressed when the dimension of the spacetime increases. The dS space is the only background in which we can discuss analytically the pair creation process of higher dimensional black holes, since the C-metric and the Ernst solutions, which describe, respectively, a pair accelerated by a string and by an electromagnetic field, are not known yet in a higher dimensional spacetime

Tandem electrostatic accelerators for BNCT

International Nuclear Information System (INIS)

Ma, J.C.

1994-01-01

The development of boron neutron capture therapy (BNCT) into a viable therapeutic modality will depend, in part, on the availability of suitable neutron sources compatible with installation in a hospital environment. Low-energy accelerator-based intense neutron sources, using electrostatic or radio frequency quadrupole proton accelerators have been suggested for this purpose and are underdevelopment at several laboratories. New advances in tandem electrostatic accelerator technology now allow acceleration of the multi-milliampere proton beams required to produce therapeutic neutron fluxes for BNCT. The relatively compact size, low weight and high power efficiency of these machines make them particularly attractive for installation in a clinical or research facility. The authors will describe the limitations on ion beam current and available neutron flux from tandem accelerators relative to the requirements for BNCT research and therapy. Preliminary designs and shielding requirements for a tandern accelerator-based BNCT research facility will also be presented

Language-Related Values, Reading Amount, and Reading Comprehension in Students with Migration Backgrounds

Science.gov (United States)

El-Khechen, Wahiba; Ferdinand, Hanna D.; Steinmayr, Ricarda; McElvany, Nele

2016-01-01

Background: Although various studies on general language performance have investigated determinants of students' reading comprehension (e.g., reading amount), they have paid insufficient attention to how students perceive parental values influence their language-related values and behaviour--and, as a consequence, their performance. This is…

Timing of Pulsed Prompt Gamma Rays for Background Discrimination

International Nuclear Information System (INIS)

Hueso-Gonzalez, F.; Golnik, C.; Berthel, M.; Dreyer, A.; Kormoll, T.; Rohling, H.; Pausch, G.; Enghardt, W.; Fiedler, F.; Heidel, K.; Schoene, S.; Schwengner, R.; Wagner, A.

2013-06-01

In the context of particle therapy, particle range verification is a major challenge for the quality assurance of the treatment. One approach is the measurement of the prompt gamma rays resulting from the tissue irradiation. A Compton camera based on several planes of position sensitive gamma ray detectors, together with an imaging algorithm, is expected to reconstruct the prompt gamma ray emission density profile, which is correlated with the dose distribution. At Helmholtz- Zentrum Dresden-Rossendorf (HZDR) and OncoRay, a camera prototype has been developed consisting of two scatter planes (CdZnTe cross strip detectors) and an absorber plane (Lu 2 SiO 5 block detector). The data acquisition is based on VME electronics and handled by software developed on the ROOT platform. The prototype was tested at the linear electron accelerator ELBE at HZDR, which was set up to produce bunched bremsstrahlung photons. Their spectrum has similarities with the one expected from prompt gamma rays in the clinical case, and these are also bunched with the accelerator frequency. The time correlation between the pulsed prompt photons and the measured signals was used for background discrimination, achieving a time resolution of 3 ns (2 ns) FWHM for the CZT (LSO) detector. A time-walk correction was applied for the LSO detector and improved its resolution to 1 ns. In conclusion, the detectors are suitable for time-resolved background discrimination in pulsed clinical particle accelerators. Ongoing tasks are the test of the imaging algorithms and the quantitative comparison with simulations. Further experiments will be performed at proton accelerators. (authors)

First Measurements of Beam Backgrounds at SuperKEKB

CERN Document Server

Vahsen, S.E.; Jaegle, I.; Nakayama, H.; Aloisio, A.; Ameli, F.; Barrett, M.; Beaulieu, A.; Bosisio, L.; Branchini, P.; Browder, T.E.; Budano, A.; Cautero, G.; Cecchi, C.; Chen, Y.-T.; Chu, K.-N.; Cinabro, D.; Cristaudo, P.; de Jong, S.; de Sangro, R.; Finocchiaro, G.; Flanagan, J.; Funakoshi, Y.; Gabriel, M.; Giordano, R.; Giuressi, D.; Hedges, M. T.; Honkanen, N.; Ikeda, H.; Ishibashi, T.; Kaji, H.; Kanazawa, K.; Kiesling, C.; Koirala, S.; Križan, P.; La Licata, C.; Lanceri, L.; Liau, J.-J.; Lin, F.-H.; Lin, J.-C.; Liptak, Z.; Longo, S.; Manoni, E.; Marinas, C.; Miyabayashi, K.; Mulyani, E.; Morita, A.; Nakao, M.; Nayak, M.; Ohnishi, Y.; Passeri, A.; Poffenberger, P.; Ritzert, M.; Roney, J M.; Rossi, A.; Röder, T.; Seddon, R.M.; Seong, I.S.; Shiu, J.-G.; Simon, F.; Soloviev, Y.; Suetsugu, Y.; Szalay, M.; Terui, S.; Tortone, G.; van der Kolk, N.; Vitale, L.; Wang, M.Z.; Windel, H.; Yokoyama, S.

2018-01-01

The high design luminosity of the SuperKEKB electron-positron collider is expected to result in challenging levels of beam-induced backgrounds in the interaction region. Properly simulating and mitigating these backgrounds is critical to the success of the Belle~II experiment. We report on measurements performed with a suite of dedicated beam background detectors, collectively known as BEAST II, during the so-called Phase 1 commissioning run of SuperKEKB in 2016, which involved operation of both the high energy ring (HER) of 7 GeV electrons as well as the low energy ring (LER) of 4 GeV positrons. We describe the BEAST II detector systems, the simulation of beam backgrounds, and the measurements performed. The measurements include standard ones of dose rates versus accelerator conditions, and more novel investigations, such as bunch-by-bunch measurements of injection backgrounds and measurements sensitive to the energy spectrum and angular distribution of fast neutrons. We observe beam-gas, Touschek, beam-dust...

The Accelerator Reliability Forum

CERN Document Server

Lüdeke, Andreas; Giachino, R

2014-01-01

A high reliability is a very important goal for most particle accelerators. The biennial Accelerator Reliability Workshop covers topics related to the design and operation of particle accelerators with a high reliability. In order to optimize the over-all reliability of an accelerator one needs to gather information on the reliability of many different subsystems. While a biennial workshop can serve as a platform for the exchange of such information, the authors aimed to provide a further channel to allow for a more timely communication: the Particle Accelerator Reliability Forum [1]. This contribution will describe the forum and advertise it’s usage in the community.

Feasibility studies of RFQ based 14C accelerator mass spectrometry

International Nuclear Information System (INIS)

Guo Zhiyu; Liu Kexin; Yan Xueqing; Xie Yi; Fang Jiaxun; Chen Jiaer

2007-01-01

Electrostatic accelerators with terminal voltage less than 1 MeV have been successfully used for 14 C AMS. This contribution shows that a small RFQ accelerator may also be suitable for AMS 14 C measurements. A well-designed RFQ accelerator can realize a low energy spread and high isotopic selection with a length of less than 1 m and reasonable power consumption. Compared with small tandem accelerators, a RFQ does not need isolation gas and can accept much higher beam currents. Its stripper would be at ground potential and there would be no further acceleration after stripping, so the background from charge exchange processes should be lower. The RFQ design and system are described

Improvements in or relating to the protection of thermoelectric devices against shocks and accelerations

International Nuclear Information System (INIS)

Brown, M.H.; Myatt, J.

1979-01-01

Heart pacemakers are protected against shock and acceleration by surrounding the heat source, but not in contact with the source or the thermoelectric unit, with a plurity of spring fingers. These arrest the radioactive source in the event of movement on its resilient mounting of the thermoelectric unit relative to the casing in excess of a predetermined amount. (UK)

Industrial use of electron accelerators

International Nuclear Information System (INIS)

Tabata, Y.

1980-01-01

Use of accelerators in various fields of Japan is reviewed. The total number of accelerators in Japan and its relation with others fields, the number of accelerators for use in radiation processing, comparison between the use of low and high energy machines, etc... is done. (E.G.) [pt

The Impacts of Language Background and Language-Related Disorders in Auditory Processing Assessment

Science.gov (United States)

Loo, Jenny Hooi Yin; Bamiou, Doris-Eva; Rosen, Stuart

2013-01-01

Purpose: To examine the impact of language background and language-related disorders (LRDs--dyslexia and/or language impairment) on performance in English speech and nonspeech tests of auditory processing (AP) commonly used in the clinic. Method: A clinical database concerning 133 multilingual children (mostly with English as an additional…

Felsenkeller shallow-underground accelerator laboratory for nuclear astrophysics

Science.gov (United States)

Bemmerer, D.; Cowan, T. E.; Gohl, S.; Ilgner, C.; Junghans, A. R.; Reinhardt, T. P.; Rimarzig, B.; Reinicke, S.; Röder, M.; Schmidt, K.; Schwengner, R.; Stöckel, K.; Szücs, T.; Takács, M.; Wagner, A.; Wagner, L.; Zuber, K.

2015-05-01

Favored by the low background in underground laboratories, low-background accelerator-based experiments are an important tool to study nuclear reactions involving stable charged particles. This technique has been used for many years with great success at the 0.4 MV LUNA accelerator in the Gran Sasso laboratory in Italy, proteced from cosmic rays by 1400 m of rock. However, the nuclear reactions of helium and carbon burning and the neutron source reactions for the astrophysical s-process require higher beam energies than those available at LUNA. Also the study of solar fusion reactions necessitates new data at higher energies. As a result, in the present NuPECC long range plan for nuclear physics in Europe, the installation of one or more higher-energy underground accelerators is strongly recommended. An intercomparison exercise has been carried out using the same HPGe detector in a typical nuclear astrophysics setup at several sites, including the Dresden Felsenkeller underground laboratory. It was found that its rock overburden of 45m rock, together with an active veto against the remaining muon flux, reduces the background to a level that is similar to the deep underground scenario. Based on this finding, a used 5 MV pelletron tandem with 250 μA upcharge current and external sputter ion source has been obtained and transported to Dresden. Work on an additional radio-frequency ion source on the high voltage terminal is underway. The project is now fully funded. The installation of the accelerator in the Felsenkeller is expected for the near future. The status of the project and the planned access possibilities for external users will be reported.

CAS - CERN Accelerator School: Course on Digital Signal Processing

CERN Document Server

Digital Signal Processing; CAS 2007

2008-01-01

These proceedings present the lectures given at the twenty-first specialized course organized by the CERN Accelerator School (CAS), the topic being Digital Signal Processing. The course was held in Sigtuna, Sweden, from 31 May–9 June 2007. This is the first time this topic has been selected for a specialized course. Taking into account the number of related applications currently in use in accelerators around the world, it was recognized that such a topic should definitively be incorporated into the CAS series of specialized courses. The specific aim of the course was to introduce the participants to the use and programming of Digital Signal Processors (DSPs) and Field Programmable Gate Arrays (FPGAs) evaluation boards. The course consisted of lectures in the mornings covering fundamental background knowledge in mathematics, controls theory, design tools, programming hardware platforms, and implementation details. In the afternoons the students split into two groups with people working in pairs. One group w...

KEK digital accelerator

Directory of Open Access Journals (Sweden)

T. Iwashita

2011-07-01

Full Text Available The High Energy Accelerator Research Organization KEK digital accelerator (KEK-DA is a renovation of the KEK 500 MeV booster proton synchrotron, which was shut down in 2006. The existing 40 MeV drift tube linac and rf cavities have been replaced by an electron cyclotron resonance (ECR ion source embedded in a 200 kV high-voltage terminal and induction acceleration cells, respectively. A DA is, in principle, capable of accelerating any species of ion in all possible charge states. The KEK-DA is characterized by specific accelerator components such as a permanent magnet X-band ECR ion source, a low-energy transport line, an electrostatic injection kicker, an extraction septum magnet operated in air, combined-function main magnets, and an induction acceleration system. The induction acceleration method, integrating modern pulse power technology and state-of-art digital control, is crucial for the rapid-cycle KEK-DA. The key issues of beam dynamics associated with low-energy injection of heavy ions are beam loss caused by electron capture and stripping as results of the interaction with residual gas molecules and the closed orbit distortion resulting from relatively high remanent fields in the bending magnets. Attractive applications of this accelerator in materials and biological sciences are discussed.

Pair creation of anti-de Sitter black holes on a cosmic string background

International Nuclear Information System (INIS)

Dias, Oscar J.C.

2004-01-01

We analyze the quantum process in which a cosmic string breaks in an anti-de Sitter (AdS) background, and a pair of charged or neutral black holes is produced at the ends of the strings. The energy to materialize and accelerate the pair comes from the string tension. In an AdS background this is the only study done on the process of production of a pair of correlated black holes with spherical topology. The acceleration A of the produced black holes is necessarily greater than √(|Λ|/3), where Λ A bh /4 , where A bh is the black hole horizon area. We also conclude that the general behavior of the pair creation rate with the mass and acceleration of the black holes is similar in the AdS, flat and de Sitter cases, and our AdS results reduce to the ones of the flat case when Λ→0

Accelerators

CERN Multimedia

CERN. Geneva

2001-01-01

The talk summarizes the principles of particle acceleration and addresses problems related to storage rings like LEP and LHC. Special emphasis will be given to orbit stability, long term stability of the particle motion, collective effects and synchrotron radiation.

Study and realization of an electron linear accelerator. Dynamics of accelerated electrons

International Nuclear Information System (INIS)

Bernard, J.

1966-12-01

The theoretical characteristics of the electron linear accelerator are: 30 MeV for the energy W S and 250 mA for the peak current I c . The main utilization is the intense production of fast neutrons by the reactions (γ,n) and (γ,f) induced in a target of natural uranium by the accelerated electrons. In the first part of the thesis, relative to the study and the realization of the accelerator, a new equation of dispersion is established analytically when the guide is loaded with round-edged irises. The relation is compared with the equation established by CHU and Hansen, WALKINSHAW, KVASIL in the case of a guide loaded with flat-edged irises. The experimental and theoretical curves of dispersion are compared. The accuracy of every relation of dispersion is estimated. The second part of the thesis is relative to the theoretical study of the electrons dynamics in the guide; it allows the derivation of the parameters of the beam: dispersion of phase, energy, dispersion of energy and the relation W S = f (I c ). The results relative to the first experiments are given and compared with the theoretical expectations. (author) [fr

Gas-filled capillaries for plasma-based accelerators

International Nuclear Information System (INIS)

Filippi, F; Anania, M P; Brentegani, E; Biagioni, A; Chiadroni, E; Ferrario, M; Pompili, R; Romeo, S; Cianchi, A; Zigler, A

2017-01-01

Plasma Wakefield Accelerators are based on the excitation of large amplitude plasma waves excited by either a laser or a particle driver beam. The amplitude of the waves, as well as their spatial dimensions and the consequent accelerating gradient depend strongly on the background electron density along the path of the accelerated particles. The process needs stable and reliable plasma sources, whose density profile must be controlled and properly engineered to ensure the appropriate accelerating mechanism. Plasma confinement inside gas filled capillaries have been studied in the past since this technique allows to control the evolution of the plasma, ensuring a stable and repeatable plasma density distribution during the interaction with the drivers. Moreover, in a gas filled capillary plasma can be pre-ionized by a current discharge to avoid ionization losses. Different capillary geometries have been studied to allow the proper temporal and spatial evolution of the plasma along the acceleration length. Results of this analysis obtained by varying the length and the number of gas inlets will be presented. (paper)

Gas-filled capillaries for plasma-based accelerators

Science.gov (United States)

Filippi, F.; Anania, M. P.; Brentegani, E.; Biagioni, A.; Cianchi, A.; Chiadroni, E.; Ferrario, M.; Pompili, R.; Romeo, S.; Zigler, A.

2017-07-01

Plasma Wakefield Accelerators are based on the excitation of large amplitude plasma waves excited by either a laser or a particle driver beam. The amplitude of the waves, as well as their spatial dimensions and the consequent accelerating gradient depend strongly on the background electron density along the path of the accelerated particles. The process needs stable and reliable plasma sources, whose density profile must be controlled and properly engineered to ensure the appropriate accelerating mechanism. Plasma confinement inside gas filled capillaries have been studied in the past since this technique allows to control the evolution of the plasma, ensuring a stable and repeatable plasma density distribution during the interaction with the drivers. Moreover, in a gas filled capillary plasma can be pre-ionized by a current discharge to avoid ionization losses. Different capillary geometries have been studied to allow the proper temporal and spatial evolution of the plasma along the acceleration length. Results of this analysis obtained by varying the length and the number of gas inlets will be presented.

Diagnostics for induction accelerators

International Nuclear Information System (INIS)

Fessenden, T.J.

1996-04-01

The induction accelerator was conceived by N. C. Christofilos and first realized as the Astron accelerator that operated at LLNL from the early 1960's to the end of 1975. This accelerator generated electron beams at energies near 6 MeV with typical currents of 600 Amperes in 400 ns pulses. The Advanced Test Accelerator (ATA) built at Livermore's Site 300 produced 10,000 Ampere beams with pulse widths of 70 ns at energies approaching 50 MeV. Several other electron and ion induction accelerators have been fabricated at LLNL and LBNL. This paper reviews the principal diagnostics developed through efforts by scientists at both laboratories for measuring the current, position, energy, and emittance of beams generated by these high current, short pulse accelerators. Many of these diagnostics are closely related to those developed for other accelerators. However, the very fast and intense current pulses often require special diagnostic techniques and considerations. The physics and design of the more unique diagnostics developed for electron induction accelerators are presented and discussed in detail

Production and applications of quasi-monoenergetic electron bunches in laser-plasma based accelerators

International Nuclear Information System (INIS)

Glinec, Y.; Faure, J.; Ewald, F.; Lifschitz, A.; Malka, V.

2006-01-01

Plasmas are attractive media for the next generation of compact particle accelerators because they can sustain electric fields larger than those in conventional accelerators by three orders of magnitude. However, until now, plasma-based accelerators have produced relatively poor quality electron beams even though for most practical applications, high quality beams are required. In particular, beams from laser plasma-based accelerators tend to have a large divergence and very large energy spreads, meaning that different particles travel at different speeds. The combination of these two problems makes it difficult to utilize these beams. Here, we demonstrate the production of high quality and high energy electron beams from laser-plasma interaction: in a distance of 3 mm, a very collimated and quasi-monoenergetic electron beam is emitted with a 0.5 nanocoulomb charge at 170 ± 20 MeV. In this regime, we have observed very nonlinear phenomena, such as self-focusing and temporal self-shortenning down to 10 fs durations. Both phenomena increase the excitation of the wakefield. The laser pulse drives a highly nonlinear wakefield, able to trap and accelerate plasma background electrons to a single energy. We will review the different regimes of electron acceleration and we will show how enhanced performances can be reached with state-of-the-art ultrashort laser systems. Applications such as gamma radiography of such electron beams will also be discussed

JAERI 20 MV tandem accelerator

International Nuclear Information System (INIS)

Tsukada, Kineo; Harada, Kichinosuke

1977-01-01

Accelerators have been developed as the experimental apparatuses for the studies on nuclei and elementary particles. One direction of the development is the acceleration of protons and electrons to more and more high energy, and another direction is the acceleration of heavy ions up to uranium to several MeV up to several hundreds MeV. However recently, accelerators are used as the useful tools for the studies in wider fields. There are electrostatic acceleration and high frequency acceleration in ion acceleration, and at present, super-large accelerators are high frequency acceleration type. In Japan Atomic Energy Research Institute, it was decided in 1975 to construct an electrostatic accelerator of tandem type in order to accelerate heavy ions. In case of the electrostatic acceleration, the construction is relatively simple, the acceleration of heavy ions is easy, the property of the ion beam is very good, and the energy is stable. Especially, the tandem type is convenient for obtaining high energy. The tandem accelerator of 20 MV terminal voltage was ordered from the National Electrostatics Corp., USA, and is expected to be completed in 1978. The significance of heavy ion acceleration in the development and research of atomic energy, tandem van de Graaff accelerators, the JAERI 20MV tandem accelerator, and the research project with this accelerator are described. (Kako, I.)

Development of the Accelerator Mass Spectrometry technology at the Comenius University in Bratislava

Science.gov (United States)

Povinec, Pavel P.; Masarik, Jozef; Ješkovský, Miroslav; Kaizer, Jakub; Šivo, Alexander; Breier, Robert; Pánik, Ján; Staníček, Jaroslav; Richtáriková, Marta; Zahoran, Miroslav; Zeman, Jakub

2015-10-01

An Accelerator Mass Spectrometry (AMS) laboratory has been established at the Centre for Nuclear and Accelerator Technologies (CENTA) at the Comenius University in Bratislava comprising of a MC-SNICS ion source, 3 MV Pelletron tandem accelerator, and an analyzer of accelerated ions. The preparation of targets for 14C and 129I AMS measurements is described in detail. The development of AMS techniques for potassium, uranium and thorium analysis in radiopure materials required for ultra-low background underground experiments is briefly mentioned.

Re-Identification of the Many-World Background of Special Relativity as Four-World Background. Part I

Directory of Open Access Journals (Sweden)

Adekugbe A. O. J.

2011-01-01

Full Text Available The pair of co-existing symmetrical universes, referred to as our (or positive universe and negative universe, isolated and shown to constitute a two-world background for the special theory of relativity (SR in previous papers, encompasses another pair of symmetrical universes, referred to as positive time-universe and negative time-universe. The Euclidean 3-spaces (in the context of SR of the positive time-universe and the negative time-universe constitute the time dimensions of our (or positive universe and the negative universe respectively, relative to observers in the Euclidean 3-spaces of our universe and the negative universe and the Euclidean 3-spaces of our universe and the negative universe constitute the time dimensions of the positive time-universe and the negative time-universe respectively, relative to observers in the Euclidean 3-spaces of the positive time-universe and the negative time-universe. Thus time is a secondary concept derived from the concept of space according to this paper. The one-dimensional particle or object in time dimension to every three-dimensional particle or object in 3- space in our universe is a three-dimensional particle or object in 3-space in the positive time-universe. Perfect symmetry of natural laws is established among the resulting four universes and two outstanding issues about the new spacetime / intrinsic spacetime geometrical representation of Lorentz transformation / intrinsic Lorentz transformation in the two-world picture, developed in the previous papers, are resolved within the larger four-world picture in this first part of this paper.

Re-Identification of the Many-World Background of Special Relativity as Four-World Background. Part I

Directory of Open Access Journals (Sweden)

Adekugbe A. O. J.

2011-01-01

Full Text Available The pair of co-existing symmetrical universes, referred to as our (or positive universe and negative universe, isolated and shown to constitute a two-world background for the special theory of relativity (SR in previous papers, encompasses another pair of symmetrical universes, referred to as positive time-universe and negative time-universe. The Euclidean 3-spaces (in the context of SR of the positive time-universe and the negative time-universe constitute the time dimensions of our (or positive universe and the negative universe respectively, relative to observers in the Euclidean 3-spaces of our universe and the negative universe and the Euclidean 3-spaces of our universe and the negative universe constitute the time dimensions of the positive time-universe and the negative time-universe respectively, relative to observers in the Euclidean 3-spaces of the positive time-universe and the negative time-universe. Thus time is a secondary concept derived from the concept of space according to this paper. The one-dimensional particle or object in time dimension to every three-dimensional particle or object in 3-space in our universe is a three-dimensional particle or object in 3-space in the positive time-universe. Perfect symmetry of natural laws is established among the resulting four universes and two outstanding issues about the new spacetime/intrinsic spacetime geometrical representation of Lorentz transformation/intrinsic Lorentz transformation in the two-world picture, developed in the previous papers, are resolved within the larger four-world picture in this first part of this paper.

Contribution of genetic background, traditional risk factors, and HIV-related factors to coronary artery disease events in HIV-positive persons

NARCIS (Netherlands)

Rotger, Margalida; Glass, Tracy R; Junier, Thomas; Lundgren, Jens; Neaton, James D; Poloni, Estella S; van 't Wout, Angélique B; Lubomirov, Rubin; Colombo, Sara; Martinez, Raquel; Rauch, Andri; Günthard, Huldrych F; Neuhaus, Jacqueline; Wentworth, Deborah; van Manen, Danielle; Gras, Luuk A; Schuitemaker, Hanneke; Albini, Laura; Torti, Carlo; Jacobson, Lisa P; Li, Xiuhong; Kingsley, Lawrence A; Carli, Federica; Guaraldi, Giovanni; Ford, Emily S; Sereti, Irini; Hadigan, Colleen; Martinez, Esteban; Arnedo, Mireia; Egaña-Gorroño, Lander; Gatell, Jose M; Law, Matthew; Bendall, Courtney; Petoumenos, Kathy; Rockstroh, Jürgen; Wasmuth, Jan-Christian; Kabamba, Kabeya; Delforge, Marc; De Wit, Stephane; Berger, Florian; Mauss, Stefan; de Paz Sierra, Mariana; Losso, Marcelo; Belloso, Waldo H; Leyes, Maria; Campins, Antoni; Mondi, Annalisa; De Luca, Andrea; Bernardino, Ignacio; Barriuso-Iglesias, Mónica; Torrecilla-Rodriguez, Ana; Gonzalez-Garcia, Juan; Arribas, José R; Fanti, Iuri; Gel, Silvia; Puig, Jordi; Negredo, Eugenia; Gutierrez, Mar; Domingo, Pere; Fischer, Julia; Fätkenheuer, Gerd; Alonso-Villaverde, Carlos; Macken, Alan; Woo, James; McGinty, Tara; Mallon, Patrick; Mangili, Alexandra; Skinner, Sally; Wanke, Christine A; Reiss, Peter; Weber, Rainer; Bucher, Heiner C; Fellay, Jacques; Telenti, Amalio; Tarr, Philip E; Schölvinck, Elisabeth H.

BACKGROUND: Persons infected with human immunodeficiency virus (HIV) have increased rates of coronary artery disease (CAD). The relative contribution of genetic background, HIV-related factors, antiretroviral medications, and traditional risk factors to CAD has not been fully evaluated in the

Acceleration transforms and statistical kinetic models

International Nuclear Information System (INIS)

LuValle, M.J.; Welsher, T.L.; Svoboda, K.

1988-01-01

For a restricted class of problems a mathematical model of microscopic degradation processes, statistical kinetics, is developed and linked through acceleration transforms to the information which can be obtained from a system in which the only observable sign of degradation is sudden and catastrophic failure. The acceleration transforms were developed in accelerated life testing applications as a tool for extrapolating from the observable results of an accelerated life test to the dynamics of the underlying degradation processes. A particular concern of a physicist attempting to interpreted the results of an analysis based on acceleration transforms is determining the physical species involved in the degradation process. These species may be (a) relatively abundant or (b) relatively rare. The main results of this paper are a theorem showing that for an important subclass of statistical kinetic models, acceleration transforms cannot be used to distinguish between cases a and b, and an example showing that in some cases falling outside the restrictions of the theorem, cases a and b can be distinguished by their acceleration transforms

Diagnostics for induction accelerators

International Nuclear Information System (INIS)

Fessenden, T.J.

1997-01-01

The induction accelerator was conceived by N. C. Christofilos and first realized as the Astron accelerator that operated at Lawrence Livermore National Laboratory (LLNL) from the early 1960s to the end of 1975. This accelerator generated electron beams at energies near 6 MeV with typical currents of 600 Amperes in 400-ns pulses. The Advanced Test Accelerator (ATA) built at Livermore close-quote s Site 300 produced 10,000-Ampere beams with pulse widths of 70 ns at energies approaching 50 MeV. Several other electron and ion induction accelerators have been fabricated at LLNL and Lawrence Berkeley National Laboratory (LBNL). This paper reviews the principal diagnostics developed through efforts by scientists at both laboratories for measuring the current, position, energy, and emittance of beams generated by these high-current, short-pulse accelerators. Many of these diagnostics are closely related to those developed for other accelerators. However, the very fast and intense current pulses often require special diagnostic techniques and considerations. The physics and design of the more unique diagnostics developed for electron induction accelerators are presented and discussed in detail. copyright 1997 American Institute of Physics

Resolving the Conflict Between Associative Overdominance and Background Selection

Science.gov (United States)

Zhao, Lei; Charlesworth, Brian

2016-01-01

In small populations, genetic linkage between a polymorphic neutral locus and loci subject to selection, either against partially recessive mutations or in favor of heterozygotes, may result in an apparent selective advantage to heterozygotes at the neutral locus (associative overdominance) and a retardation of the rate of loss of variability by genetic drift at this locus. In large populations, selection against deleterious mutations has previously been shown to reduce variability at linked neutral loci (background selection). We describe analytical, numerical, and simulation studies that shed light on the conditions under which retardation vs. acceleration of loss of variability occurs at a neutral locus linked to a locus under selection. We consider a finite, randomly mating population initiated from an infinite population in equilibrium at a locus under selection. With mutation and selection, retardation occurs only when S, the product of twice the effective population size and the selection coefficient, is of order 1. With S >> 1, background selection always causes an acceleration of loss of variability. Apparent heterozygote advantage at the neutral locus is, however, always observed when mutations are partially recessive, even if there is an accelerated rate of loss of variability. With heterozygote advantage at the selected locus, loss of variability is nearly always retarded. The results shed light on experiments on the loss of variability at marker loci in laboratory populations and on the results of computer simulations of the effects of multiple selected loci on neutral variability. PMID:27182952

Development of the Accelerator Mass Spectrometry technology at the Comenius University in Bratislava

Energy Technology Data Exchange (ETDEWEB)

Povinec, Pavel P., E-mail: povinec@fmph.uniba.sk; Masarik, Jozef; Ješkovský, Miroslav; Kaizer, Jakub; Šivo, Alexander; Breier, Robert; Pánik, Ján; Staníček, Jaroslav; Richtáriková, Marta; Zahoran, Miroslav; Zeman, Jakub

2015-10-15

An Accelerator Mass Spectrometry (AMS) laboratory has been established at the Centre for Nuclear and Accelerator Technologies (CENTA) at the Comenius University in Bratislava comprising of a MC-SNICS ion source, 3 MV Pelletron tandem accelerator, and an analyzer of accelerated ions. The preparation of targets for {sup 14}C and {sup 129}I AMS measurements is described in detail. The development of AMS techniques for potassium, uranium and thorium analysis in radiopure materials required for ultra-low background underground experiments is briefly mentioned.

Historical evolution of nuclear energy systems development and related activities in JAERI. Fission, fusion, accelerator utilization

Energy Technology Data Exchange (ETDEWEB)

Tone, Tatsuzo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

2001-03-01

Overview of the historical evolution of nuclear energy systems development and related activities in JAERI is given in the report. This report reviews the research and development for light water reactor, fast breeder reactor, high temperature gas reactor, fusion reactor and utilization of accelerator-based neutron source. (author)

Relative measurements of fast neutron contamination in 18-MV photon beams from two linear accelerators and a betatron

International Nuclear Information System (INIS)

Gur, D.; Bukovitz, A.G.; Rosen, J.C.; Holmes, B.G.

1979-01-01

Fast neutron contamination in photon beams in the 20 MV range have been reported in recent years. In order to determine if the variations were due mainly to differences in measurement procedures, or inherent in the design of the accelerators, three different 18-MV (BJR) photon beams were compared using identical analytical techniques. The units studied were a Philips SL/75-20 and a Siemens Mevatron-20 linear accelerators and a Schimadzu betatron. Gamma spectroscopy of an activated aluminum foil was the method used. By comparing the relative amounts of neutron contamination, errors associated with absolute measurements such as detector efficiency and differences in activation foils were eliminated. Fast neutron contaminations per rad of x rays in a ratio of 6.7:3.7:1 were found for the Philips, Schimadzu and Siemens accelerators, respectively

Proceedings of CAS - CERN Accelerator School: Course on Superconductivity for Accelerators

Energy Technology Data Exchange (ETDEWEB)

Bailey, R [European Organization for Nuclear Research, Geneva (Switzerland)

2014-07-01

These proceedings collate lectures given at the twenty-seventh specialized course organised by the CERN Accelerator School (CAS). The course was held at the Ettore Majorana Foundation and Centre for Scientific Culture (EMFCSC) in Erice, Italy, from 24 April to 4 May 2013. Following recapitulation lectures on basic accelerator physics and superconductivity, the course covered topics related to the design, production and operation of superconducting RF systems and superconducting magnets for accelerators. The participants pursued one of six case studies in order to get ’hands-on’ experience of the issues connected with the design of superconducting systems. A series of topical seminars completed the programme.

Asynchronous Communication: Investigating the Influences of Relational Elements and Background on the Framing Structure of Emails

Science.gov (United States)

AlAfnan, Mohammad Awad

2015-01-01

This study explored the influences of relational elements and the background of communicators on the framing structure of email messages that were exchanged in an educational Institute in Malaysia. The investigation revealed that social distance played a more significant role than power relations as Malaysian respondents are, generally, more…

1+3 covariant cosmic microwave background anisotropies I: Algebraic relations for mode and multipole expansions

International Nuclear Information System (INIS)

Gebbie, Tim; Ellis, G.F.R.

2000-01-01

This is the first of a series of papers systematically extending a 1+3 covariant and gauge-invariant treatment of kinetic theory in curved space-times to a treatment of cosmic microwave background temperature anisotropies arising from inhomogeneities in the early universe. The present paper deals with algebraic issues, both generically and in the context of models linearised about Robertson-Walker geometries. The approach represents radiation anisotropies by projected symmetric and trace-free tensors. The angular correlation functions for the mode coefficients are found in terms of these quantities, following the Wilson-Silk approach, but derived and dealt with in 1+3 covariant and gauge-invariant form. The covariant multipole and mode-expanded angular correlation functions are related to the usual treatments in the literature. The 1+3 covariant and gauge-invariant mode expansion is related to the coordinate approach by linking the Legendre functions to the projected symmetric trace-free representation, using a covariant addition theorem for the tensors to generate the Legendre polynomial recursion relation. This paper lays the foundation for further papers in the series, which use this formalism in a covariant and gauge-invariant approach to developing solutions of the Boltzmann and Liouville equations for the cosmic microwave background before and after decoupling, thus providing a unified covariant and gauge-invariant derivation of the variety of approaches to cosmic microwave background anisotropies in the current literature, as well as a basis for extension of the theory to include nonlinearities

Switching the Fermilab Accelerator Control System to a relational database

International Nuclear Information System (INIS)

Shtirbu, S.

1993-01-01

The accelerator control system (open-quotes ACNETclose quotes) at Fermilab is using a made-in-house, Assembly language, database. The database holds device information, which is mostly used for finding out how to read/set devices and how to interpret alarms. This is a very efficient implementation, but it lacks the needed flexibility and forces applications to store data in private/shared files. This database is being replaced by an off-the-shelf relational database (Sybase 2 ). The major constraints on switching are the necessity to maintain/improve response time and to minimize changes to existing applications. Innovative methods are used to help achieve the required performance, and a layer seven gateway simulates the old database for existing programs. The new database is running on a DEC ALPHA/VMS platform, and provides better performance. The switch is also exposing problems with the data currently stored in the database, and is helping in cleaning up erroneous data. The flexibility of the new relational database is going to facilitate many new applications in the future (e.g. a 3D presentation of device location). The new database is expected to fully replace the old database during this summer's shutdown

Enhancing proton acceleration by using composite targets

Energy Technology Data Exchange (ETDEWEB)

Bulanov, S. S.; Esarey, E.; Schroeder, C. B.; Bulanov, S. V.; Esirkepov, T. Zh.; Kando, M.; Pegoraro, F.; Leemans, W. P.

2015-07-10

Efficient laser ion acceleration requires high laser intensities, which can only be obtained by tightly focusing laser radiation. In the radiation pressure acceleration regime, where the tightly focused laser driver leads to the appearance of the fundamental limit for the maximum attainable ion energy, this limit corresponds to the laser pulse group velocity as well as to another limit connected with the transverse expansion of the accelerated foil and consequent onset of the foil transparency. These limits can be relaxed by using composite targets, consisting of a thin foil followed by a near critical density slab. Such targets provide guiding of a laser pulse inside a self-generated channel and background electrons, being snowplowed by the pulse, compensate for the transverse expansion. The use of composite targets results in a significant increase in maximum ion energy, compared to a single foil target case.

Observational probes of cosmic acceleration

International Nuclear Information System (INIS)

Weinberg, David H.; Mortonson, Michael J.; Eisenstein, Daniel J.; Hirata, Christopher; Riess, Adam G.; Rozo, Eduardo

2013-01-01

The accelerating expansion of the universe is the most surprising cosmological discovery in many decades, implying that the universe is dominated by some form of “dark energy” with exotic physical properties, or that Einstein’s theory of gravity breaks down on cosmological scales. The profound implications of cosmic acceleration have inspired ambitious efforts to understand its origin, with experiments that aim to measure the history of expansion and growth of structure with percent-level precision or higher. We review in detail the four most well established methods for making such measurements: Type Ia supernovae, baryon acoustic oscillations (BAO), weak gravitational lensing, and the abundance of galaxy clusters. We pay particular attention to the systematic uncertainties in these techniques and to strategies for controlling them at the level needed to exploit “Stage IV” dark energy facilities such as BigBOSS, LSST, Euclid, and WFIRST. We briefly review a number of other approaches including redshift-space distortions, the Alcock–Paczynski effect, and direct measurements of the Hubble constant H 0 . We present extensive forecasts for constraints on the dark energy equation of state and parameterized deviations from General Relativity, achievable with Stage III and Stage IV experimental programs that incorporate supernovae, BAO, weak lensing, and cosmic microwave background data. We also show the level of precision required for clusters or other methods to provide constraints competitive with those of these fiducial programs. We emphasize the value of a balanced program that employs several of the most powerful methods in combination, both to cross-check systematic uncertainties and to take advantage of complementary information. Surveys to probe cosmic acceleration produce data sets that support a wide range of scientific investigations, and they continue the longstanding astronomical tradition of mapping the universe in ever greater detail over ever

Observational probes of cosmic acceleration

Energy Technology Data Exchange (ETDEWEB)

Weinberg, David H., E-mail: dhw@astronomy.ohio-state.edu [Department of Astronomy, Ohio State University, Columbus, OH (United States); Center for Cosmology and Astro-Particle Physics, Ohio State University, Columbus, OH (United States); Mortonson, Michael J. [Center for Cosmology and Astro-Particle Physics, Ohio State University, Columbus, OH (United States); Eisenstein, Daniel J. [Steward Observatory, University of Arizona, Tucson, AZ (United States); Harvard College Observatory, Cambridge, MA (United States); Hirata, Christopher [California Institute of Technology, Pasadena, CA (United States); Riess, Adam G. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD (United States); Rozo, Eduardo [Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL (United States)

2013-09-10

The accelerating expansion of the universe is the most surprising cosmological discovery in many decades, implying that the universe is dominated by some form of “dark energy” with exotic physical properties, or that Einstein’s theory of gravity breaks down on cosmological scales. The profound implications of cosmic acceleration have inspired ambitious efforts to understand its origin, with experiments that aim to measure the history of expansion and growth of structure with percent-level precision or higher. We review in detail the four most well established methods for making such measurements: Type Ia supernovae, baryon acoustic oscillations (BAO), weak gravitational lensing, and the abundance of galaxy clusters. We pay particular attention to the systematic uncertainties in these techniques and to strategies for controlling them at the level needed to exploit “Stage IV” dark energy facilities such as BigBOSS, LSST, Euclid, and WFIRST. We briefly review a number of other approaches including redshift-space distortions, the Alcock–Paczynski effect, and direct measurements of the Hubble constant H{sub 0}. We present extensive forecasts for constraints on the dark energy equation of state and parameterized deviations from General Relativity, achievable with Stage III and Stage IV experimental programs that incorporate supernovae, BAO, weak lensing, and cosmic microwave background data. We also show the level of precision required for clusters or other methods to provide constraints competitive with those of these fiducial programs. We emphasize the value of a balanced program that employs several of the most powerful methods in combination, both to cross-check systematic uncertainties and to take advantage of complementary information. Surveys to probe cosmic acceleration produce data sets that support a wide range of scientific investigations, and they continue the longstanding astronomical tradition of mapping the universe in ever greater detail over

Auroral electron acceleration

International Nuclear Information System (INIS)

Bryant, D.A.

1989-10-01

Two theories of auroral electron acceleration are discussed. Part 1 examines the currently widely held view that the acceleration is an ordered process in a quasi-static electric field. It is suggested that, although there are many factors seeming to support this theory, the major qualifications and uncertainties that have been identified combine to cast serious doubt over its validity. Part 2 is devoted to a relatively new interpretation in terms of stochastic acceleration in turbulent electric fields. This second theory, which appears to account readily for most known features of the electron distribution function, is considered to provide a more promising approach to this central question in magnetospheric plasma physics. (author)

Ion acceleration in modulated electron beams

International Nuclear Information System (INIS)

Bonch-Osmolovskij, A.G.; Dolya, S.N.

1977-01-01

A method of ion acceleration in modulated electron beams is considered. Electron density and energy of their rotational motion are relatively low. However the effective ion-accelerating field is not less than 10 MeV/m. The electron and ion numbers in an individual bunch are also relatively small, although the number of produced bunches per time unit is great. Some aspects of realization of the method are considered. Possible parameters of the accelerator are given. At 50 keV electron energy and 1 kA beam current a modulation is realized at a wave length of 30 cm. The ion-accelerating field is 12 MeV/m. The bunch number is 2x10 3 in one pulse at a gun pulse duration of 2 μs. With a pulse repetition frequency of 10 2 Hz the number of accelerated ions can reach 10 13 -10 14 per second

Accelerator microanalysis

International Nuclear Information System (INIS)

Tuniz, C.

1997-01-01

Particle accelerators have been developed more than sixty years ago to investigate nuclear and atomic phenomena. A major shift toward applications of accelerators in the study of materials structure and composition in inter-disciplinary projects has been witnessed in the last two decades. The Australian Nuclear Science and Technology Organisation (ANSTO) has developed advanced research programs based on the use of particle and photon beams. Atmospheric pollution problems are investigated at the 3 MV Van de Graff accelerator using ion beam analysis techniques to detect toxic elements in aerosol particles. High temperature superconductor and semiconductor materials are characterised using the recoil of iodine and other heavy ions produced at ANTARES, the 10-MV Tandem accelerator. A heavy-ion microprobe is presently being developed at ANTARES to map elemental concentrations of specific elements with micro-size resolution. An Accelerator mass Spectrometry (AMS) system has been developed at ANSTO for the ultra-sensitive detection of Carbon-14, Iodine-129 and other long-lived radioisotopes. This AMS spectrometer is a key instrument for climate change studies and international safeguards. ANSTO is also managing the Australian Synchrotron Research program based on facilities developed at the Photon Factory (Japan) and at the Advanced Photon Source (USA). Advanced projects in biology, materials chemistry, structural condensed matter and other disciplines are being promoted by a consortium involving Australian universities and research institutions. This paper will review recent advances in the use of particle accelerators, with a particular emphasis on applications developed at ANSTO and related to problems of international concern, such as global environmental change, public health and nuclear proliferation

Multi-beam linear accelerator EVT

Energy Technology Data Exchange (ETDEWEB)

Teryaev, Vladimir E., E-mail: vladimir_teryaev@mail.ru [Omega-P, Inc., New Haven, CT 06510 (United States); Kazakov, Sergey Yu. [Fermilab, Batavia, IL 60510 (United States); Hirshfield, Jay L. [Omega-P, Inc., New Haven, CT 06510 (United States); Yale University, New Haven, CT 06511 (United States)

2016-09-01

A novel electron multi-beam accelerator is presented. The accelerator, short-named EVT (Electron Voltage Transformer) belongs to the class of two-beam accelerators. It combines an RF generator and essentially an accelerator within the same vacuum envelope. Drive beam-lets and an accelerated beam are modulated in RF modulators and then bunches pass into an accelerating structure, comprising uncoupled with each other and inductive tuned cavities, where the energy transfer from the drive beams to the accelerated beam occurs. A phasing of bunches is solved by choice correspond distances between gaps of the adjacent cavities. Preliminary results of numerical simulations and the initial specification of EVT operating in S-band, with a 60 kV gun and generating a 2.7 A, 1.1 MV beam at its output is presented. A relatively high efficiency of 67% and high design average power suggest that EVT can find its use in industrial applications.

Data-driven modeling of background and mine-related acidity and metals in river basins

International Nuclear Information System (INIS)

Friedel, Michael J.

2014-01-01

A novel application of self-organizing map (SOM) and multivariate statistical techniques is used to model the nonlinear interaction among basin mineral-resources, mining activity, and surface-water quality. First, the SOM is trained using sparse measurements from 228 sample sites in the Animas River Basin, Colorado. The model performance is validated by comparing stochastic predictions of basin-alteration assemblages and mining activity at 104 independent sites. The SOM correctly predicts (>98%) the predominant type of basin hydrothermal alteration and presence (or absence) of mining activity. Second, application of the Davies–Bouldin criteria to k-means clustering of SOM neurons identified ten unique environmental groups. Median statistics of these groups define a nonlinear water-quality response along the spatiotemporal hydrothermal alteration-mining gradient. These results reveal that it is possible to differentiate among the continuum between inputs of background and mine-related acidity and metals, and it provides a basis for future research and empirical model development. The trained self-organizing map is used to determine upstream hydrothermal alteration (AS – acid sulfate; PROP – propylitic, PROP-V – propylitic veins, QSP – quartz-sericite-pyrite, WSP – weak-sericite-pyrite; Mining activity: MINES) from water-quality measurements in the Animas river basin, Colorado, USA. The white hexagons are sized proportional to the number of water-quality samples associated with that SOM neuron. Highlights: • We model surface-water quality response using a self-organizing map and multivariate statistics. • Applying Davies–Bouldin criteria to k-means clusters defines ten environmental response groups. • The approach differentiates between background and mine-related acidity and metals. -- These results reveal that it is possible to differentiate among the continuum between inputs of background and mine-related acidity and metals

Vancouver Accelerator Conference

Energy Technology Data Exchange (ETDEWEB)

Anon.

1985-06-15

Anyone who contends that particle physics is conducted in an ivory tower, not contributing to other fields of science or to humanity at large, should have attended the 1985 Particle Accelerator Conference in Vancouver. Over a thousand participants contributed 781 papers and only a fraction were actually related to accelerators for high energy physics. The majority of present developments are in the service of other fields of science, for alternative power sources, for medicine, for industrial applications, etc.

Vancouver Accelerator Conference

International Nuclear Information System (INIS)

Anon.

1985-01-01

Anyone who contends that particle physics is conducted in an ivory tower, not contributing to other fields of science or to humanity at large, should have attended the 1985 Particle Accelerator Conference in Vancouver. Over a thousand participants contributed 781 papers and only a fraction were actually related to accelerators for high energy physics. The majority of present developments are in the service of other fields of science, for alternative power sources, for medicine, for industrial applications, etc

Within season and carry-over effects following exposure of grassland species mixtures to increasing background ozone

Energy Technology Data Exchange (ETDEWEB)

Hayes, Felicity, E-mail: fhay@ceh.ac.uk [Centre for Ecology and Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW (United Kingdom); Mills, Gina; Harmens, Harry; Wyness, Kirsten [Centre for Ecology and Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW (United Kingdom)

2011-10-15

Few studies have investigated effects of increased background ozone in the absence of episodic peaks, despite a predicted increase throughout the northern hemisphere over the coming decades. In this study Leontodon hispidus was grown with Anthoxanthum odoratum or Dactylis glomerata and exposed in the UK to one of eight background ozone concentrations for 20 weeks in solardomes. Seasonal mean ozone concentrations ranged from 21.4 to 102.5 ppb. Ozone-induced senescence of L. hispidus was enhanced when grown with the more open canopy of A. odoratum compared to the denser growing D. glomerata. There was increased cover with increasing ozone exposure for both A. odoratum and D. glomerata, which resulted in an increase in the grass:Leontodon cover ratio in both community types. Carry-over effects of the ozone exposure were observed, including delayed winter die-back of L. hispidus and acceleration in the progression from flowers to seed-heads in the year following ozone exposure. - Highlights: > Increased background ozone concentrations increased the grass:forb cover ratio. > Competing grass species influenced ozone enhanced senescence of Leontodon hispidus. > Ozone delayed winter die-back of leaves of L. hispidus. > Flowering was accelerated for L. hispidus in the year following ozone exposure. - Increased background ozone enhanced leaf senescence and caused carry-over effects including reduced winter die-back and an acceleration in flowering the next year.

Saudi Arabia: Background and U.S. Relations

Science.gov (United States)

2015-04-29

23, 2013. 6 Background information on Saudi cabinet members is available at http://www.saudiembassy.net/about/ Biographies - of-Ministers.aspx. Saudi...territories it occupied in 1967, (2) agree to the establishment of a Palestinian state with a capital in East Jerusalem , and provide for the (3) “[a...compromise on Palestinian sovereignty in Jerusalem .” Elhanan Miller, “Arab ministers back Abbas in rejecting ‘Jewish’ Israel,” Times of Israel, January

Use of heavy ion accelerators in fusion reactor-related radiation-damage studies

International Nuclear Information System (INIS)

Taylor, A.; Dobson, D.A.

1974-01-01

The heavy-ion accelerator has become an important tool in the study of the fundamentals of radiation damage in fission- and fusion-reactor materials. Present facilities for such studies within the Materials Science Division at Argonne National Laboratory are provided by two complementary accelerator systems. Examples of the work carried out are discussed

Phase-of-flight method for setting the accelerating fields in the ion linear accelerator

International Nuclear Information System (INIS)

Dvortsov, S.V.; Lomize, L.G.

1983-01-01

For setting amplitudes and phases of accelerating fields in multiresonator ion accelerators presently Δt-procedure is used. The determination and setting of two unknown parameters of RF-field (amplitude and phase) in n-resonator is made according to the two increments of particle time-of-flight, measured experimentally: according to the change of the particle time-of-flight Δt 1 in the n-resonator, during the field switching in the resonator, and according to the change of Δt 2 of the time-of-flight in (n+1) resonator without RF-field with the switching of accelerating field in the n-resonator. When approaching the accelerator exit the particle energy increases, relative energy increment decreases and the accuracy of setting decreases. To enchance the accuracy of accelerating fields setting in a linear ion accelerator a phase-of-flight method is developed, in which for the setting of accelerating fields the measured time-of-flight increment Δt only in one resonator is used (the one in which the change of amplitude and phase is performed). Results of simulation of point bunch motion in the IYaI AN USSR linear accelerator are presented

Linear accelerator use in the nuclear field

International Nuclear Information System (INIS)

Lecomte, J.-C.

Radiography of internal conformity is performed on weldments and thick castings using linear accelerators. The basic principles relating to linear accelerators are outlined and their advantages over Co 60 sources described. Linear accelerator operation related requirements are presented as well as the use of this apparatus as a method for volumetric inspection, during fabrication of French Nuclear Steam Supply Systems (NSSS). Finally the resources needed to use this technique as an inspection method is dealt with [fr

The Next Linear Collider Test Accelerator

International Nuclear Information System (INIS)

Ruth, R.D.; Adolphsen, C.; Bane, K.

1993-04-01

During the past several years, there has been tremendous progress the development of the RF system and accelerating structures for a Next Linear Collider (NLC). Developments include high-power klystrons, RF pulse compression systems and damped/detuned accelerator structures to reduce wakefields. In order to integrate these separate development efforts into an actual X-band accelerator capable of accelerating the electron beams necessary for an NLC, we are building an NLC Test Accelerator (NLCTA). The goal of the NLCTA is to bring together all elements of the entire accelerating system by constructing and reliably operating an engineered model of a high-gradient linac suitable for the NLC. The NLCTA will serve as a testbed as the design of the NLC evolves. In addition to testing the RF acceleration system, the NLCTA is designed to address many questions related to the dynamics of the beam during acceleration. In this paper, we will report oil the status of the design, component development, and construction of the NLC Test Accelerator

Influence of Complete Coriolis Force on the Dispersion Relation of Ocean Internal-wave in a Background Currents Field

Directory of Open Access Journals (Sweden)

Liu Yongjun

2015-01-01

Full Text Available In this thesis, the influence of complete Coriolis force (the model includes both the vertical and horizontal components of Coriolis force on the dispersion relation of ocean internal-wave under background currents field are studied, it is important to the study of ocean internal waves in density-stratified ocean. We start from the control equation of sea water movement in the background of the non-traditional approximation, and the vertical velocity solution is derived where buoyancy frequency N(z gradually varies with the ocean depth z. The results show that the influence of complete Coriolis force on the dispersion relation of ocean internal-wave under background currents field is obvious, and these results provide strong evidence for the understanding of dynamic process of density stratified ocean internal waves.

The Accelerator Markup Language and the Universal Accelerator Parser

International Nuclear Information System (INIS)

Sagan, D.; Forster, M.; Cornell U., LNS; Bates, D.A.; LBL, Berkeley; Wolski, A.; Liverpool U.; Cockcroft Inst. Accel. Sci. Tech.; Schmidt, F.; CERN; Walker, N.J.; DESY; Larrieu, T.; Roblin, Y.; Jefferson Lab; Pelaia, T.; Oak Ridge; Tenenbaum, P.; Woodley, M.; SLAC; Reiche, S.; UCLA

2006-01-01

A major obstacle to collaboration on accelerator projects has been the sharing of lattice description files between modeling codes. To address this problem, a lattice description format called Accelerator Markup Language (AML) has been created. AML is based upon the standard eXtensible Markup Language (XML) format; this provides the flexibility for AML to be easily extended to satisfy changing requirements. In conjunction with AML, a software library, called the Universal Accelerator Parser (UAP), is being developed to speed the integration of AML into any program. The UAP is structured to make it relatively straightforward (by giving appropriate specifications) to read and write lattice files in any format. This will allow programs that use the UAP code to read a variety of different file formats. Additionally, this will greatly simplify conversion of files from one format to another. Currently, besides AML, the UAP supports the MAD lattice format

Progress of the Felsenkeller Shallow-Underground Accelerator for Nuclear Astrophysics

Science.gov (United States)

Bemmerer, D.; Cavanna, F.; Cowan, T. E.; Grieger, M.; Hensel, T.; Junghans, A. R.; Ludwig, F.; Müller, S. E.; Rimarzig, B.; Reinicke, S.; Schulz, S.; Schwengner, R.; Stöckel, K.; Szücs, T.; Takács, M. P.; Wagner, A.; Wagner, L.; Zuber, K.

Low-background experiments with stable ion beams are an important tool for putting the model of stellar hydrogen, helium, and carbon burning on a solid experimental foundation. The pioneering work in this regard has been done by the LUNA collaboration at Gran Sasso, using a 0.4 MV accelerator. In the present contribution, the status of the project for a higher-energy underground accelerator is reviewed. Two tunnels of the Felsenkeller underground site in Dresden, Germany, are currently being refurbished for the installation of a 5 MV high-current Pelletron accelerator. Construction work is on schedule and expected to complete in August 2017. The accelerator will provide intense, 50 µA, beams of 1H+, 4He+, and 12C+ ions, enabling research on astrophysically relevant nuclear reactions with unprecedented sensitivity.

Report of the consultant's meeting on applications of accelerator based analysis

International Nuclear Information System (INIS)

1998-07-01

At the present meeting, applications of accelerator based analytical methods, often referred as ion beam analysis (IBA) methods, to the following areas have been discussed: materials (including thin films), Earth sciences (including environmental studies), biology and medicine, art and archaeology (cultural heritage), and other applications (including forensic applications). This report gives brief overview of IBA applications in these areas, with short background about accelerators needed and corresponding analytical techniques

Radiative damping in plasma-based accelerators

Directory of Open Access Journals (Sweden)

I. Yu. Kostyukov

2012-11-01

Full Text Available The electrons accelerated in a plasma-based accelerator undergo betatron oscillations and emit synchrotron radiation. The energy loss to synchrotron radiation may seriously affect electron acceleration. The electron dynamics under combined influence of the constant accelerating force and the classical radiation reaction force is studied. It is shown that electron acceleration cannot be limited by radiation reaction. If initially the accelerating force was stronger than the radiation reaction force, then the electron acceleration is unlimited. Otherwise the electron is decelerated by radiative damping up to a certain instant of time and then accelerated without limits. It is shown that regardless of the initial conditions the infinite-time asymptotic behavior of an electron is governed by a self-similar solution providing that the radiative damping becomes exactly equal to 2/3 of the accelerating force. The relative energy spread induced by the radiative damping decreases with time in the infinite-time limit. The multistage schemes operating in the asymptotic acceleration regime when electron dynamics is determined by the radiation reaction are discussed.

A system for monitoring the radiation effects of a proton linear accelerator

Energy Technology Data Exchange (ETDEWEB)

Skorkin, V. M., E-mail: skorkin@inr.ru; Belyanski, K. L.; Skorkin, A. V. [Russian Academy of Sciences, Institute for Nuclear Research (Russian Federation)

2016-12-15

The system for real-time monitoring of radioactivity of a high-current proton linear accelerator detects secondary neutron emission from proton beam losses in transport channels and measures the activity of radionuclides in gas and aerosol emissions and the radiation background in the environment affected by a linear accelerator. The data provided by gamma, beta, and neutron detectors are transferred over a computer network to the central server. The system allows one to monitor proton beam losses, the activity of gas and aerosol emissions, and the radiation emission level of a linear accelerator in operation.

Stochastic particle acceleration by plasma waves in AGN jets

International Nuclear Information System (INIS)

Li, Hui; Colgate, S.A.; Miller, J.A.

1997-01-01

The free energy stored in the stressed magnetic fields in AGN jets could be dissipated via generating turbulent plasma waves. The authors review several key wave-particle resonant interactions and point out the importance of a broad wave spectrum. Under several idealized assumptions, they show that the transit-time damping process can accelerate electrons to TeV energies in an AGN jet environment, and present a preliminary calculation on the evolution of plasma wave, electron, and photon distributions. The authors especially emphasize several open questions on particle acceleration by waves, and argue that a plausible scenario is to energize electrons out of the thermal background via transit-time damping and further accelerate them by the parallel propagating right-handed waves

Dusty-Plasma Particle Accelerator

Science.gov (United States)

Foster, John E.

2005-01-01

A dusty-plasma apparatus is being investigated as means of accelerating nanometer- and micrometer-sized particles. Applications for the dusty-plasma particle accelerators fall into two classes: Simulation of a variety of rapidly moving dust particles and micrometeoroids in outer-space environments that include micrometeoroid streams, comet tails, planetary rings, and nebulae and Deposition or implantation of nanoparticles on substrates for diverse industrial purposes that could include hardening, increasing thermal insulation, altering optical properties, and/or increasing permittivities of substrate materials. Relative to prior apparatuses used for similar applications, dusty-plasma particle accelerators offer such potential advantages as smaller size, lower cost, less complexity, and increased particle flux densities. A dusty-plasma particle accelerator exploits the fact that an isolated particle immersed in plasma acquires a net electric charge that depends on the relative mobilities of electrons and ions. Typically, a particle that is immersed in a low-temperature, partially ionized gas, wherein the average kinetic energy of electrons exceeds that of ions, causes the particle to become negatively charged. The particle can then be accelerated by applying an appropriate electric field. A dusty-plasma particle accelerator (see figure) includes a plasma source such as a radio-frequency induction discharge apparatus containing (1) a shallow cup with a biasable electrode to hold the particles to be accelerated and (2) a holder for the substrate on which the particles are to impinge. Depending on the specific design, a pair of electrostatic-acceleration grids between the substrate and discharge plasma can be used to both collimate and further accelerate particles exiting the particle holder. Once exposed to the discharge plasma, the particles in the cup quickly acquire a negative charge. Application of a negative voltage pulse to the biasable electrode results in the

Accelerator mass spectrometry-current status in techniques and applications

International Nuclear Information System (INIS)

Imamura, Mineo; Nagai, Hisao; Kobayashi, Koichi.

1991-01-01

Accelerator mass spectrometry (AMS) is the mass spectrometry by incorporating an accelerator. After samples are ionized, they are accelerated to a certain energy, and mass, energy, nuclear charge (atomic number) are distinguished, and ion counting is made one by one with a heavy ion detector. For the measurement of long half-life radioisotopes, mass spectrometry has been used because of the high sensitivity, but in low energy mass spectrometry, there are the difficulties due to the mixing of the molecular ions having nearly same mass and the existence of isobars. One of the methods solving these difficulties is an accelerator which enables background-free measurement. The progress of AMS is briefly described, and at present, it is carried out in about 30 facilities in the world. In AMS, the analysis is carried out in the order of the ionization of samples, the acceleration of beam, the electron stripping with a thin film, the sorting of the momentum and energy of beam and the identification of particles. The efficiency, sensitivity and accuracy of detection and the application are reported. (K.I.)

Swedish earthquakes and acceleration probabilities

International Nuclear Information System (INIS)

Slunga, R.

1979-03-01

A method to assign probabilities to ground accelerations for Swedish sites is described. As hardly any nearfield instrumental data is available we are left with the problem of interpreting macroseismic data in terms of acceleration. By theoretical wave propagation computations the relation between seismic strength of the earthquake, focal depth, distance and ground accelerations are calculated. We found that most Swedish earthquake of the area, the 1904 earthquake 100 km south of Oslo, is an exception and probably had a focal depth exceeding 25 km. For the nuclear power plant sites an annual probability of 10 -5 has been proposed as interesting. This probability gives ground accelerations in the range 5-20 % for the sites. This acceleration is for a free bedrock site. For consistency all acceleration results in this study are given for bedrock sites. When applicating our model to the 1904 earthquake and assuming the focal zone to be in the lower crust we get the epicentral acceleration of this earthquake to be 5-15 % g. The results above are based on an analyses of macrosismic data as relevant instrumental data is lacking. However, the macroseismic acceleration model deduced in this study gives epicentral ground acceleration of small Swedish earthquakes in agreement with existent distant instrumental data. (author)

The Extended Relativity Theory in Clifford Spaces

CERN Document Server

Castro, C

2004-01-01

A brief review of some of the most important features of the Extended Relativity theory in Clifford-spaces ( $C$-spaces) is presented whose " point" coordinates are noncommuting Clifford-valued quantities and which incoporate the lines, areas, volumes, .... degrees of freedom associated with the collective particle, string, membrane, ... dynamics of the $p$-loop histories (closed p-branes) living in target $D$-dimensional spacetime backgrounds. $C$-space Relativity naturally incoporates the ideas of an invariant length (Planck scale), maximal acceleration, noncommuting coordinates, supersymmetry, holography, superluminal propagation, higher derivative gravity with torsion and variable dimensions/signatures that allows to study the dynamics of all (closed ) p-branes, for all values of $ p $, in a unified footing. It resolves the ordering ambiguities in QFT and the problem of time in Cosmology. A discussion of the maximal-acceleration Relativity principle in phase-spaces follows along with the study of the inva...

Characteristics of particle beam acceleration on KUMS tandem electrostatic accelerator 5SDH-2

OpenAIRE

谷池, 晃; 古山, 雄一; 北村, 晃

2006-01-01

The KUMS tandem electrostatic accelerator, 5SDH-2, was installed in 1996. Ten years have passed since it installed and we obtain some data for accelerator operations. We report the particle beam characteristics such as relation between beam species and switcher magnet current, and dependence of ion charge fraction on stripper gas thickness. We also try to generate nitrogen ion beams, and low energy ion beams.

Using Octupoles for Background Control in Linear Colliders an Exploratory Conceptual Study

CERN Document Server

Pitthan, R

1999-01-01

If one adds a suited Octupole (or an even higher multipole) lattice to linear collider Quadrupole FODO lattices, the amplifying properties of the combined lattice drive particles in the tails, but not those in the core, into resonant losses. This approach is quite different in concept and beam dynamics impact from past proposed use of non-linear elements for collimation. This non-traditional scheme for background control has the added advantage that most, or maybe all, of the Halo collimation can be done using the lever arm of the real estate of the main accelerators, thus reducing the costly length of a separate dedicated collimation section and also unifying machine protection and background control. Simulations of particle distributions are presented. This approach requires co operation by the designers of the accelerators, the beam delivery system, and the Detector, because a careful balance between sometimes conflicting requirements has to be found. As a second component of this approach the use of Octup...

Superconducting magnets for particle large accelerators

International Nuclear Information System (INIS)

Kircher, F.

1994-01-01

The different accelerator types (linear, circular) and the advantages of using superconductivity in particle accelerator are first reviewed. Characteristics of some large superconducting accelerators (Tevatron, HERA, RHIC, LHC CERN) are presented. The design features related to accelerator magnets are reviewed: magnet reproducibility, stability, field homogeneity, etc. and the selected design characteristics are discussed: manufacturing method, winding, shielding, cryostat. CEA involvement in this domain mainly addressing quadrupoles, is presented together with the Large Hadron Collider (LHC) project at CERN. Characteristics and design of detector magnets are also described. 5 figs., 2 tabs

Advances of Accelerator Physics and Technologies

CERN Document Server

1993-01-01

This volume, consisting of articles written by experts with international repute and long experience, reviews the state of the art of accelerator physics and technologies and the use of accelerators in research, industry and medicine. It covers a wide range of topics, from basic problems concerning the performance of circular and linear accelerators to technical issues and related fields. Also discussed are recent achievements that are of particular interest (such as RF quadrupole acceleration, ion sources and storage rings) and new technologies (such as superconductivity for magnets and RF ca

The Dresden Felsenkeller shallow-underground accelerator laboratory for nuclear astrophysics - Status and first physics program

Energy Technology Data Exchange (ETDEWEB)

Ilgner, Ch. [Nuclear Astrophysics group, Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiation Physics, Dresden (Germany)

2015-07-01

Favored by the low background in underground laboratories, low-background accelerator-based experiments are an important tool to study nuclear reactions involving stable charged particles. This technique has been used for many years with great success at the 0.4 MV LUNA accelerator in the Gran Sasso laboratory in Italy, protected from cosmic rays by 1400 m of rock. However, the nuclear reactions of helium and carbon burning and the neutron source reactions for the astrophysical s-process require higher beam energies than those available at LUNA. Also the study of solar fusion reactions necessitates new data at higher energies. As a result, in the present NuPECC long range plan for nuclear physics in Europe, the installation of one or more higher-energy underground accelerators is strongly recommended. An intercomparison exercise using the same High-Purity Ge detector at several sites has shown that, with a combination of 45 m rock overburden, as can be found in the Felsenkeller underground site in Dresden, and an active veto against the remaining muon flux, in a typical nuclear astrophysics setup a background level can be achieved that is similar to the deep underground scenario as in the Gran- Sasso underground laboratory, for instance. Recently, a muon background study and geodetic measurements were carried out by the REGARD group. It was estimated that the rock overburden at the place of the future ion accelerator is equivalent to 130 m of water. The maximum muon flux measured was 2.5 m{sup -2} sr{sup -1} s{sup -1}, in the direction of the tunnel entrance. Based on this finding, a used 5 MV pelletron tandem accelerator with 250 μA up-charge current and external sputter ion source has been obtained and transported to Dresden. Work on an additional radio-frequency ion source on the high voltage terminal is in progress and far advanced. The installation of the accelerator in the Felsenkeller is expected for the near future. The status of the project and the

A low-neutron background slow-positron source

International Nuclear Information System (INIS)

White, M. M.

1998-01-01

The addition of a thermionic rf gun [1] and a photocathode rf gun will allow the Advanced Photon Source (APS) linear accelerator (linac) [2] [3] to become a free-electron laser (FEL) driver [4]. As the FEL project progresses, the existing high-charge DC thermionic gun will no longer be critical to APS operation and could be used to generate high-energy or low-energy electrons to drive a slow-positron source. We investigated possibilities to create a useful low-energy source that could operate semi-independently and would have a low neutron background

Linear accelerator accelerating module to suppress back-acceleration of field-emitted particles

Science.gov (United States)

Benson, Stephen V.; Marhauser, Frank; Douglas, David R.; Ament, Lucas J. P.

2017-12-05

A method for the suppression of upstream-directed field emission in RF accelerators. The method is not restricted to a certain number of cavity cells, but requires similar operating field levels in all cavities to efficiently annihilate the once accumulated energy. Such a field balance is desirable to minimize dynamic RF losses, but not necessarily achievable in reality depending on individual cavity performance, such as early Q.sub.0-drop or quench field. The method enables a significant energy reduction for upstream-directed electrons within a relatively short distance. As a result of the suppression of upstream-directed field emission, electrons will impact surfaces at rather low energies leading to reduction of dark current and less issues with heating and damage of accelerator components as well as radiation levels including neutron generation and thus radio-activation.

CAS CERN Accelerator School: Power converters for particle accelerators

International Nuclear Information System (INIS)

Turner, S.

1990-01-01

This volume presents the proceedings of the fifth specialized course organized by the CERN Accelerator School, the subject on this occasion being power converters for particle accelerators. The course started with lectures on the classification and topologies of converters and on the guidelines for achieving high performance. It then went on to cover the more detailed aspects of feedback theory, simulation, measurements, components, remote control, fault diagnosis and equipment protection as well as systems and grid-related problems. The important topics of converter specification, procurement contract management and the likely future developments in semiconductor components were also covered. Although the course was principally directed towards DC and slow-pulsed supplies, lectures were added on fast converters and resonant excitation. Finally the programme was rounded off with three seminars on the related fields of Tokamak converters, battery energy storage for electric vehicles, and the control of shaft generators in ships. (orig.)

IMPULSIVE ACCELERATION OF CORONAL MASS EJECTIONS. II. RELATION TO SOFT X-RAY FLARES AND FILAMENT ERUPTIONS

Energy Technology Data Exchange (ETDEWEB)

Bein, B. M.; Berkebile-Stoiser, S.; Veronig, A. M.; Temmer, M. [Kanzelhoehe Observatory-IGAM, Institute of Physics, University of Graz, Universitaetsplatz 5, A-8010 Graz (Austria); Vrsnak, B. [Hvar Observatory, Faculty of Geodesy, University of Zagreb, Kaciceva 26, HR-10000 Zagreb (Croatia)

2012-08-10

Using high time cadence images from the STEREO EUVI, COR1, and COR2 instruments, we derived detailed kinematics of the main acceleration stage for a sample of 95 coronal mass ejections (CMEs) in comparison with associated flares and filament eruptions. We found that CMEs associated with flares reveal on average significantly higher peak accelerations and lower acceleration phase durations, initiation heights, and heights, at which they reach their peak velocities and peak accelerations. This means that CMEs that are associated with flares are characterized by higher and more impulsive accelerations and originate from lower in the corona where the magnetic field is stronger. For CMEs that are associated with filament eruptions we found only for the CME peak acceleration significantly lower values than for events that were not associated with filament eruptions. The flare rise time was found to be positively correlated with the CME acceleration duration and negatively correlated with the CME peak acceleration. For the majority of the events the CME acceleration starts before the flare onset (for 75% of the events) and the CME acceleration ends after the soft X-ray (SXR) peak time (for 77% of the events). In {approx}60% of the events, the time difference between the peak time of the flare SXR flux derivative and the peak time of the CME acceleration is smaller than {+-}5 minutes, which hints at a feedback relationship between the CME acceleration and the energy release in the associated flare due to magnetic reconnection.

Design Concepts for Muon-Based Accelerators

Energy Technology Data Exchange (ETDEWEB)

Ryne, R. D. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Berg, J. S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Kirk, H. G. [Brookhaven National Lab. (BNL), Upton, NY (United States); Palmer, R. B. [Brookhaven National Lab. (BNL), Upton, NY (United States); Stratkis, D. [Brookhaven National Lab. (BNL), Upton, NY (United States); Alexahin, Y. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Bross, A. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Gollwitzer, K. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Mokhov, N. V. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Neuffer, D. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Palmer, M. A. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Yonehara, K. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Snopok, P. [IIT, Chicago, IL (United States); Bogacz, A. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Roberts, T. J. [Muons Inc., Batavia, IL (United States); Delahaye, J. -P. [SLAC National Accelerator Lab., Menlo Park, CA (United States)

2015-05-01

Muon-based accelerators have the potential to enable facilities at both the Intensity and the Energy Frontiers. Muon storage rings can serve as high precision neutrino sources, and a muon collider is an ideal technology for a TeV or multi-TeV collider. Progress in muon accelerator designs has advanced steadily in recent years. In regard to 6D muon cooling, detailed and realistic designs now exist that provide more than 5 order-of-magnitude emittance reduction. Furthermore, detector performance studies indicate that with suitable pixelation and timing resolution, backgrounds in the collider detectors can be significantly reduced, thus enabling high-quality physics results. Thanks to these and other advances in design & simulation of muon systems, technology development, and systems demonstrations, muon storage-ring-based neutrino sources and a muon collider appear more feasible than ever before. A muon collider is now arguably among the most compelling approaches to a multi-TeV lepton collider. This paper summarizes the current status of design concepts for muon-based accelerators for neutrino factories and a muon collider.

The Los Alamos accelerator code group

International Nuclear Information System (INIS)

Krawczyk, F.L.; Billen, J.H.; Ryne, R.D.; Takeda, Harunori; Young, L.M.

1995-01-01

The Los Alamos Accelerator Code Group (LAACG) is a national resource for members of the accelerator community who use and/or develop software for the design and analysis of particle accelerators, beam transport systems, light sources, storage rings, and components of these systems. Below the authors describe the LAACG's activities in high performance computing, maintenance and enhancement of POISSON/SUPERFISH and related codes and the dissemination of information on the INTERNET

Role of Family Background, Student Behaviors, and School-Related Beliefs in Predicting High School Dropout

Science.gov (United States)

Parr, Alyssa K.; Bonitz, Verena S.

2015-01-01

The authors' purpose was to test a parsimonious model derived from social cognitive career theory (R. W. Lent, S. D. Brown, & G. Hackett, 1994) and expectancy value theory (J. S. Eccles & A. Wigfield, 2002) that integrates groups of variables (demographic background, student behaviors, and school-related beliefs) with the goal of…

A correlation between the cosmic microwave background and large-scale structure in the Universe.

Science.gov (United States)

Boughn, Stephen; Crittenden, Robert

2004-01-01

Observations of distant supernovae and the fluctuations in the cosmic microwave background (CMB) indicate that the expansion of the Universe may be accelerating under the action of a 'cosmological constant' or some other form of 'dark energy'. This dark energy now appears to dominate the Universe and not only alters its expansion rate, but also affects the evolution of fluctuations in the density of matter, slowing down the gravitational collapse of material (into, for example, clusters of galaxies) in recent times. Additional fluctuations in the temperature of CMB photons are induced as they pass through large-scale structures and these fluctuations are necessarily correlated with the distribution of relatively nearby matter. Here we report the detection of correlations between recent CMB data and two probes of large-scale structure: the X-ray background and the distribution of radio galaxies. These correlations are consistent with those predicted by dark energy, indicating that we are seeing the imprint of dark energy on the growth of structure in the Universe.

Operational experience with compressed geometry acceleration tubes in the Oak Ridge 25URC tandem accelerator

International Nuclear Information System (INIS)

Jones, C.M.; Haynes, D.L.; Juras, R.C.; Meigs, M.J.; Ziegler, N.F.

1989-01-01

Installation of compressed geometry acceleration tubes and other associated modifications have increased the effective voltage capability of the Oak Ridge 25URC tandem accelerator by about 3 MV. Since mid-September 1988, the accelerator has been operated routinely at terminal potentials up to 24 MV and occasionally near 25 MV. In 3500 hours of full-column operation, including 1100 hours at potentials about 22 MV, no significant spark-included damage was observed. Some considerations related to further improvements in voltage performance are discussed. 7 refs., 5 figs

A Relational Database Model for Managing Accelerator Control System Software at Jefferson Lab

International Nuclear Information System (INIS)

Sally Schaffner; Theodore Larrieu

2001-01-01

The operations software group at the Thomas Jefferson National Accelerator Facility faces a number of challenges common to facilities which manage a large body of software developed in-house. Developers include members of the software group, operators, hardware engineers and accelerator physicists.One management problem has been ensuring that all software has an identified owner who is still working at the lab. In some cases, locating source code for ''orphaned'' software has also proven to be difficult. Other challenges include ensuring that working versions of all operational software are available, testing changes to operational software without impacting operations, upgrading infrastructure software (OS, compilers, interpreters, commercial packages, share/freeware, etc), ensuring that appropriate documentation is available and up to date, underutilization of code reuse, input/output file management,and determining what other software will break if a software package is upgraded. This paper will describe a relational database model which has been developed to track this type of information and make it available to managers and developers.The model also provides a foundation for developing productivity-enhancing tools for automated building, versioning, and installation of software. This work was supported by the U.S. DOE contract No. DE-AC05-84ER40150

Contribution of genetic background, traditional risk factors, and HIV-related factors to coronary artery disease events in HIV-positive persons

OpenAIRE

Rotger, Margalida; Glass, Tracy R; Junier, Thomas; Lundgren, Jens; Neaton, James D; Poloni, Estella S; van 't Wout, Angélique B; Lubomirov, Rubin; Colombo, Sara; Martinez, Raquel; Rauch, Andri; Günthard, Huldrych F; Neuhaus, Jacqueline; Wentworth, Deborah; van Manen, Danielle

2013-01-01

BACKGROUND: Persons infected with human immunodeficiency virus (HIV) have increased rates of coronary artery disease (CAD). The relative contribution of genetic background, HIV-related factors, antiretroviral medications, and traditional risk factors to CAD has not been fully evaluated in the setting of HIV infection. METHODS: In the general population, 23 common single-nucleotide polymorphisms (SNPs) were shown to be associated with CAD through genome-wide association analysis. Using the ...

Political regime change, economic liberalization and growth accelerations

NARCIS (Netherlands)

Jong-A-Pin, Richard; De Haan, Jakob

We examine whether the type of political regime, regime changes, and economic liberalization are related to economic growth accelerations. Our results show that growth accelerations are preceded by economic liberalizations. We also find that growth accelerations are less likely to happen the longer

Development of Power System for Medium Energy Accelerator

International Nuclear Information System (INIS)

Kwon, Hyeok Jung; Kim, Dae Il; Kim, Han Sung; Seol, Kyung Tae; Jang, Ji Ho; Cho, Yong Sub; Hong, In Seok; Kim, Kyung Ryul

2008-05-01

The main goal of the studies are to develop a power supply system used for 100MeV proton accelerator and to operate 20MeV accelerator which has been installed in KAERI site. The 100MeV proton accelerator uses RF cavity to accelerate beams and need RF amplifier, klystron. To operate the klystron, a high power pulse power supply is required and the power supply system should have high quality because the reliability of the power supply has critical impact on the overall reliability of accelerator system. Therefore, high power pulse power system and related technology development are inevitable for 100MeV accelerator system development. 20MeV accelerator system has been developed and installed in KAERI site, which will be used as an injector for 100MeV accelerator and supply 20MeV beam to users. A study on the 20MeV accelerator characteristics should be performed to operate the machine efficiently. In addition, this machine can be used as a test bench for developing the 100MeV accelerator components. Therefore, not only the hardware so called 'high voltage power supply', but the related technology of the high quality high voltage power system and man power can be obtained from the results of this studies. The test results of the 20MeV accelerator can be utilized as a basis for efficient operation of 100MeV accelerator and these are the ultimate objective and necessities of the study

Accelerator mass spectrometry programme at BARC-TIFR pelletron accelerator. PD-1-2

International Nuclear Information System (INIS)

Bhagwat, P.V.

2007-01-01

Accelerator mass spectrometry (AMS) is an ultra sensitive means of counting individual atoms having sufficiently long half-life and available in small amount. The 14 UD Pelletron Accelerator is an ideal machine to carry out AMS studies with heavy isotopes like 36 Cl and 129 I. Cosmogenic radioisotope 36 Cl is widely being detected using AMS as it has got applications in ground water research, radioactive waste management, atmospheric 36 Cl transport mechanism studies of Arctic Alpine ice core etc . The AMS programme at the 14 UD Mumbai Pelletron Accelerator has taken off with the installation of the state of the art Terminal Potential Stabilizer setup and operation of the accelerator in Generating Volt Meter (GVM) mode. Feasibility studies have been carried out for detection/identification of 14 C from a charcoal sample and 3 He in natural Helium. As the primary interest of AMS programme at Mumbai Pelletron Accelerator is related to the cosmogenic nuclei, 36 Cl and 129 I, a segmented gas detector developed for identification of 36 Cl was tested for performance. Recently a beam chopper required for this measurement has also been developed

The acceleration and propagation of energetic particles in turbulent cosmic plasmas

International Nuclear Information System (INIS)

Achterberg, A.

1981-01-01

This thesis concentrates on the acceleration and propagation of energetic particles in turbulent cosmic plasmas. The stochastic acceleration of relativistic electrons by long-wavelength weak magnetohydrodynamic turbulence is considered and a model is discussed that allows the determination of both the electron energy spectrum and the wavenumber spectrum of the magnetohydrodynamic turbulence in a consistent way. The question of second phase acceleration in large solar flares and the precise form of the force exerted on the background plasma when Alfven waves are generated by fast particles are considered. The energy balance in the shock wave acceleration, the propagation of energetic particles in a high β plasma (β>10 2 ) and sheared flow as a possible source of plasma turbulence for a magnetized plasma with field-aligned flow, are discussed. (Auth./C.F.)

Preferential acceleration in collisionless supernova shocks

International Nuclear Information System (INIS)

Hainebach, K.; Eichler, D.; Schramm, D.

1979-01-01

The preferential acceleration and resulting cosmic ray abundance enhancements of heavy elements (relative to protons) are calculated in the collisionless supernova shock acceleration model described by Eichler in earlier work. Rapidly increasing enhancements up to several tens times solar ratios are obtained as a function of atomic weight over charge at the time of acceleration. For material typical of hot phase interstellar medium, good agreement is obtained with the observed abundance enhancements

The Los Alamos accelerator code group

Energy Technology Data Exchange (ETDEWEB)

Krawczyk, F.L.; Billen, J.H.; Ryne, R.D.; Takeda, Harunori; Young, L.M.

1995-05-01

The Los Alamos Accelerator Code Group (LAACG) is a national resource for members of the accelerator community who use and/or develop software for the design and analysis of particle accelerators, beam transport systems, light sources, storage rings, and components of these systems. Below the authors describe the LAACG`s activities in high performance computing, maintenance and enhancement of POISSON/SUPERFISH and related codes and the dissemination of information on the INTERNET.

Medical uses of accelerators

International Nuclear Information System (INIS)

Bradbury, J.N.

1981-01-01

A variety of particle accelerators have either potential or already demonstrated uses in connection with medically-related research, diagnosis, and treatment. For cancer radiotherapy, nuclear particles including protons, neutrons, heavy ions, and negative pi mesons have advantages compared to conventional radiations in terms of dose localization and/or biological effectiveness. Clinical evaluations of these particles are underway at a number of institutions. Accelerator-produced radionuclides are in widespread use for research and routine diagnostic purposes. Elemental analysis techniques with charged particles and neutrons are being applied to bone, blood, and other tissues. Finally, low-dose medical imaging can be accomplished with accelerated protons and heavy ions. The status and future of these programs are discussed

Accelerator technology in tokamaks

International Nuclear Information System (INIS)

Kustom, R.L.

1977-01-01

This article presents the similarities in the technology required for high energy accelerators and tokamak fusion devices. The tokamak devices and R and D programs described in the text represent only a fraction of the total fusion program. The technological barriers to producing successful, economical tokamak fusion power plants are as many as the plasma physics problems to be overcome. With the present emphasis on energy problems in this country and elsewhere, it is very likely that fusion technology related R and D programs will vigorously continue; and since high energy accelerator technology has so much in common with fusion technology, more scientists from the accelerator community are likely to be attracted to fusion problems

Personal exposure to grass pollen: relating inhaled dose to background concentration

DEFF Research Database (Denmark)

Peel, Robert George; Hertel, Ole; Smith, Matt

2013-01-01

Background: Very few studies on human exposure to allergenic pollen have been conducted using direct methods, with background concentrations measured at city center monitoring stations typically taken as a proxy for exposure despite the inhomogeneous nature of atmospheric pollen concentrations. A...

Optimization of radiation protection for an electron accelerator used in paint cure in films approved by Brazilian Nuclear Energy Commission - CNEN, Rio de Janeiro, Brazil

International Nuclear Information System (INIS)

Rios, Denise A. da S.; Sordi, Gian Maria A.A.

2014-01-01

This study aims to evaluate the radiological protection system in an installation where there is a self-shielded accelerator Category I, used for paint curing in polymer films, in order to optimize it in situations in which it is appropriate. For this a radiometric survey was conducted in the designated areas to check rate doses at different distances from the radiation focus, in which there is a possibility of presence or persons which can reliably detect any abnormality in the accelerator operation. The comparison of the obtained values related to the accelerator operating current with the natural background radiation showed that they are compatible, signaling that the principle of optimization is already being followed

Gamma-induced Positron Spectroscopy (GiPS) at a superconducting electron linear accelerator

International Nuclear Information System (INIS)

Butterling, Maik; Anwand, Wolfgang; Cowan, Thomas E.; Hartmann, Andreas; Jungmann, Marco; Krause-Rehberg, Reinhard; Krille, Arnold; Wagner, Andreas

2011-01-01

A new and unique setup for Positron Annihilation Spectroscopy has been established and optimized at the superconducting linear electron accelerator ELBE at Helmholtz-Zentrum Dresden-Rossendorf (Germany). The intense, pulsed (26 MHz) photon source (bremsstrahlung with energies up to 16 MeV) is used to generate positrons by means of pair production throughout the entire sample volume. Due to the very short gamma bunches (< 5 ps temporal length), the facility for Gamma-induced Positron Spectroscopy (GiPS) is suitable for positron lifetime spectroscopy using the accelerator's radiofrequency as time reference. Positron lifetime and Doppler broadening Spectroscopy are employed by a coincident measurement (Age-Momentum Correlation) of the time-of-arrival and energy of the annihilation photons which in turn significantly reduces the background of scattered photons resulting in spectra with high signal to background ratios. Simulations of the setup using the GEANT4 framework have been performed to yield optimum positron generation rates for various sample materials and improved background conditions.

Gamma-induced Positron Spectroscopy (GiPS) at a superconducting electron linear accelerator

Energy Technology Data Exchange (ETDEWEB)

Butterling, Maik, E-mail: maik.butterling@googlemail.com [Martin-Luther University, Dept. of Physics, 06099 Halle (Germany); Institute of Radiation Physics, Helmholtz-Zentrum, Dresden-Rossendorf, P.O. Box 510119, 01314 Dresden (Germany); Anwand, Wolfgang; Cowan, Thomas E.; Hartmann, Andreas [Institute of Radiation Physics, Helmholtz-Zentrum, Dresden-Rossendorf, P.O. Box 510119, 01314 Dresden (Germany); Jungmann, Marco; Krause-Rehberg, Reinhard [Martin-Luther University, Dept. of Physics, 06099 Halle (Germany); Krille, Arnold; Wagner, Andreas [Institute of Radiation Physics, Helmholtz-Zentrum, Dresden-Rossendorf, P.O. Box 510119, 01314 Dresden (Germany)

2011-11-15

A new and unique setup for Positron Annihilation Spectroscopy has been established and optimized at the superconducting linear electron accelerator ELBE at Helmholtz-Zentrum Dresden-Rossendorf (Germany). The intense, pulsed (26 MHz) photon source (bremsstrahlung with energies up to 16 MeV) is used to generate positrons by means of pair production throughout the entire sample volume. Due to the very short gamma bunches (< 5 ps temporal length), the facility for Gamma-induced Positron Spectroscopy (GiPS) is suitable for positron lifetime spectroscopy using the accelerator's radiofrequency as time reference. Positron lifetime and Doppler broadening Spectroscopy are employed by a coincident measurement (Age-Momentum Correlation) of the time-of-arrival and energy of the annihilation photons which in turn significantly reduces the background of scattered photons resulting in spectra with high signal to background ratios. Simulations of the setup using the GEANT4 framework have been performed to yield optimum positron generation rates for various sample materials and improved background conditions.

Menopause accelerates biological aging

Science.gov (United States)

Levine, Morgan E.; Lu, Ake T.; Chen, Brian H.; Hernandez, Dena G.; Singleton, Andrew B.; Ferrucci, Luigi; Bandinelli, Stefania; Salfati, Elias; Manson, JoAnn E.; Quach, Austin; Kusters, Cynthia D. J.; Kuh, Diana; Wong, Andrew; Teschendorff, Andrew E.; Widschwendter, Martin; Ritz, Beate R.; Absher, Devin; Assimes, Themistocles L.; Horvath, Steve

2016-01-01

Although epigenetic processes have been linked to aging and disease in other systems, it is not yet known whether they relate to reproductive aging. Recently, we developed a highly accurate epigenetic biomarker of age (known as the “epigenetic clock”), which is based on DNA methylation levels. Here we carry out an epigenetic clock analysis of blood, saliva, and buccal epithelium using data from four large studies: the Women's Health Initiative (n = 1,864); Invecchiare nel Chianti (n = 200); Parkinson's disease, Environment, and Genes (n = 256); and the United Kingdom Medical Research Council National Survey of Health and Development (n = 790). We find that increased epigenetic age acceleration in blood is significantly associated with earlier menopause (P = 0.00091), bilateral oophorectomy (P = 0.0018), and a longer time since menopause (P = 0.017). Conversely, epigenetic age acceleration in buccal epithelium and saliva do not relate to age at menopause; however, a higher epigenetic age in saliva is exhibited in women who undergo bilateral oophorectomy (P = 0.0079), while a lower epigenetic age in buccal epithelium was found for women who underwent menopausal hormone therapy (P = 0.00078). Using genetic data, we find evidence of coheritability between age at menopause and epigenetic age acceleration in blood. Using Mendelian randomization analysis, we find that two SNPs that are highly associated with age at menopause exhibit a significant association with epigenetic age acceleration. Overall, our Mendelian randomization approach and other lines of evidence suggest that menopause accelerates epigenetic aging of blood, but mechanistic studies will be needed to dissect cause-and-effect relationships further. PMID:27457926

Background {sup 99m}Tc-methoxyisobutylisonitrile uptake of breast-specific gamma imaging in relation to background parenchymal enhancement in magnetic resonance imaging

Energy Technology Data Exchange (ETDEWEB)

Yoon, Hai-Jeon; Kim, Bom Sahn [Ewha Womans University, Department of Nuclear Medicine, Yangchun-Ku, Seoul (Korea, Republic of); Kim, Yemi [Ewha Womans University, Clinical Research Institute and Department of Conservative Dentistry, Seoul (Korea, Republic of); Lee, Jee Eun [Ewha Womans University, Department of Radiology, Seoul (Korea, Republic of)

2015-01-15

This study investigated factors that could affect background uptake of {sup 99m}Tc- methoxyisobutylisonitrile (MIBI) on normal breast by breast-specific gamma imaging (BSGI). In addition, the impact of background {sup 99m}Tc-MIBI uptake on the diagnostic performance of BSGI was further investigated. One hundred forty-five women with unilateral breast cancer who underwent BSGI, MRI, and mammography were retrospectively enrolled. Background uptake on BSGI was evaluated qualitatively and quantitatively. Patients were classified into non-dense and dense breast groups according to mammographic breast density. Background parenchymal enhancement (BPE) was rated according to BI-RADS classification. The relationship of age, menopausal status, mammographic breast density, and BPE with background {sup 99m}Tc-MIBI uptake was analyzed. Heterogeneous texture and high background uptake ratio on BSGI were significantly correlated with younger age (p < 0.001, respectively), premenopausal status (p < 0.001 and p = 0.003), dense breast (p < 0.001, respectively), and marked BPE (p < 0.001, respectively). On multivariate analysis, only BPE remained a significant factor for background MIBI uptake (p < 0.001).There was a significant reduction in positive predictive value (p = 0.024 and p = 0.002) as background MIBI uptake and BPE grade increased. BPE on MRI was the most important factor for background MIBI uptake on BSGI. High background MIBI uptake or marked BPE can diminish the diagnostic performance of BSGI. (orig.)

Mass spectrometry with accelerators.

Science.gov (United States)

Litherland, A E; Zhao, X-L; Kieser, W E

2011-01-01

As one in a series of articles on Canadian contributions to mass spectrometry, this review begins with an outline of the history of accelerator mass spectrometry (AMS), noting roles played by researchers at three Canadian AMS laboratories. After a description of the unique features of AMS, three examples, (14)C, (10)Be, and (129)I are given to illustrate the methods. The capabilities of mass spectrometry have been extended by the addition of atomic isobar selection, molecular isobar attenuation, further ion acceleration, followed by ion detection and ion identification at essentially zero dark current or ion flux. This has been accomplished by exploiting the techniques and accelerators of atomic and nuclear physics. In 1939, the first principles of AMS were established using a cyclotron. In 1977 the selection of isobars in the ion source was established when it was shown that the (14)N(-) ion was very unstable, or extremely difficult to create, making a tandem electrostatic accelerator highly suitable for assisting the mass spectrometric measurement of the rare long-lived radioactive isotope (14)C in the environment. This observation, together with the large attenuation of the molecular isobars (13)CH(-) and (12)CH 2(-) during tandem acceleration and the observed very low background contamination from the ion source, was found to facilitate the mass spectrometry of (14)C to at least a level of (14)C/C ~ 6 × 10(-16), the equivalent of a radiocarbon age of 60,000 years. Tandem Accelerator Mass Spectrometry, or AMS, has now made possible the accurate radiocarbon dating of milligram-sized carbon samples by ion counting as well as dating and tracing with many other long-lived radioactive isotopes such as (10)Be, (26)Al, (36)Cl, and (129)I. The difficulty of obtaining large anion currents with low electron affinities and the difficulties of isobar separation, especially for the heavier mass ions, has prompted the use of molecular anions and the search for alternative

Accelerating cleanup: Paths to closure

International Nuclear Information System (INIS)

1998-06-01

This report describes the status of Environmental Management's (EM's) cleanup program and a direction forward to complete achievement of the 2006 vision. Achieving the 2006 vision results in significant benefits related to accomplishing EM program objectives. As DOE sites accelerate cleanup activities, risks to public health, the environment, and worker safety and health are all reduced. Finding more efficient ways to conduct work can result in making compliance with applicable environmental requirements easier to achieve. Finally, as cleanup activities at sites are completed, the EM program can focus attention and resources on the small number of sites with more complex cleanup challenges. Chapter 1 describes the process by which this report has been developed and what it hopes to accomplish, its relationship to the EM decision-making process, and a general background of the EM mission and program. Chapter 2 describes how the site-by-site projections were constructed, and summarizes, for each of DOE's 11 Operations/Field Offices, the projected costs and schedules for completing the cleanup mission. Chapter 3 presents summaries of the detailed cleanup projections from three of the 11 Operations/Field Offices: Rocky Flats (Colorado), Richland (Washington), and Savannah River (South Carolina). The remaining eight Operations/Field Office summaries are in Appendix E. Chapter 4 reviews the cost drivers, budgetary constraints, and performance enhancements underlying the detailed analysis of the 353 projects that comprise EM's accelerated cleanup and closure effort. Chapter 5 describes a management system to support the EM program. Chapter 6 provides responses to the general comments received on the February draft of this document

Ultra-high gradient compact accelerator developments

NARCIS (Netherlands)

Brussaard, G.J.H.; Wiel, van der M.J.

2004-01-01

Continued development of relatively compact, although not quite 'table-top', lasers with peak powers in the range up to 100 TW has enabled laser-plasma-based acceleration experiments with amazing gradients of up to 1 TV/m. In order to usefully apply such gradients to 'controlled' acceleration,

Unruh effect in a real scalar field with the Higgs potential on a dynamically variable background space-time

Energy Technology Data Exchange (ETDEWEB)

Takeuchi, Shingo [Naresuan University, The Institute for Fundamental Study ' ' The Tah Poe Academia Institute' ' , Phitsanulok (Thailand)

2015-09-15

It is predicted that an accelerating electron performs a Brownian motion in the inertial frame. This Brownian motion in the inertial frame has its roots in the interaction with the thermal excitation given by the Unruh effect in the accelerating frame. If such a prediction is possible, correspondingly we propose a prediction in this study that the thermal radiation is emitted in the inertial frame from an electron heated due to the Unruh effect in the accelerating frame. The point in our prediction is, although the Unruh effect is limited in the accelerating frame, as well as that the Brownian motion rooted in the Unruh effect appears in the inertial frame, the heat of the particle appears in the inertial frame. Based on such a prediction in this paper, we investigate phenomena in the neighborhood of an accelerating electron in the inertial frame. The model we consider is the four-dimensional Klein-Gordon real scalar field model with the Higgs potential term at the finite temperature identified with the Unruh temperature on the de Sitter space-time. We calculate the one-loop effective potential in the inertial frame with the corrections by the thermal radiation rooted in the Unruh effect in the accelerating frame. In this calculation, we take into account that the background space-time is deformed due to the field theory's corrected one-loop effective potential. Based on such an analysis, we illustrate the restoration of the spontaneous symmetry breaking and the dynamical variation of the background space-time, and we examine the accelerating particle's world-line and the amount of the energy corresponding to the change of the acceleration. (orig.)

Unruh effect in a real scalar field with the Higgs potential on a dynamically variable background space-time

International Nuclear Information System (INIS)

Takeuchi, Shingo

2015-01-01

It is predicted that an accelerating electron performs a Brownian motion in the inertial frame. This Brownian motion in the inertial frame has its roots in the interaction with the thermal excitation given by the Unruh effect in the accelerating frame. If such a prediction is possible, correspondingly we propose a prediction in this study that the thermal radiation is emitted in the inertial frame from an electron heated due to the Unruh effect in the accelerating frame. The point in our prediction is, although the Unruh effect is limited in the accelerating frame, as well as that the Brownian motion rooted in the Unruh effect appears in the inertial frame, the heat of the particle appears in the inertial frame. Based on such a prediction in this paper, we investigate phenomena in the neighborhood of an accelerating electron in the inertial frame. The model we consider is the four-dimensional Klein-Gordon real scalar field model with the Higgs potential term at the finite temperature identified with the Unruh temperature on the de Sitter space-time. We calculate the one-loop effective potential in the inertial frame with the corrections by the thermal radiation rooted in the Unruh effect in the accelerating frame. In this calculation, we take into account that the background space-time is deformed due to the field theory's corrected one-loop effective potential. Based on such an analysis, we illustrate the restoration of the spontaneous symmetry breaking and the dynamical variation of the background space-time, and we examine the accelerating particle's world-line and the amount of the energy corresponding to the change of the acceleration. (orig.)

Ionizing wave via high-power HF acceleration

OpenAIRE

Mishin, Evgeny; Pedersen, Todd

2010-01-01

Recent ionospheric modification experiments with the 3.6 MW transmitter at the High Frequency Active Auroral Research Program (HAARP) facility in Alaska led to discovery of artificial ionization descending from the nominal interaction altitude in the background F-region ionosphere by ~60 km. This paper presents a physical model of an ionizing wavefront created by suprathermal electrons accelerated by the HF-excited plasma turbulence.

A periodic plasma waveguide accelerator

International Nuclear Information System (INIS)

Cole, F.T.

1985-01-01

The increasing cost of synchrotrons and storage rings has given new interest in the search for new methods of acceleration. The primary goal of this search is very large accelerating fields, because the cost of an accelerator to reach TeV energies is dominated by costs that scale with length. Very large electric fields are possible in plasmas and in lasers and many geometries are being studied that make use of plasmas, lasers, or combinations of them. In a plasma accelerator, the plasma can have several different functions. It may act as a medium for the propagation of accelerating electric-field waves. In addition, these waves may also act as a source of the energy needed to accelerate particles. Accelerators using various waves in plasmas have been built and studied in many laboratories. The device proposed here is an attempt to separate the two functions of providing a medium and providing an energy source. A relatively low-energy electron beam is used as a non-neutral plasma only to make a slow-wave medium for the propagation of an externally generated wave. The wave is a TM electromagnetic wave and the device may be thought of as a conventional electron linear accelerator with the evacuated volume and metallic envelope replaced by the electron beam. A separate second beam, which may be electrons or heavier particles, is accelerated. The application in mind here is a single-pass collider

Hanford Site background: Part 1, Soil background for nonradioactive analytes

International Nuclear Information System (INIS)

1993-04-01

The determination of soil background is one of the most important activities supporting environmental restoration and waste management on the Hanford Site. Background compositions serve as the basis for identifying soil contamination, and also as a baseline in risk assessment processes used to determine soil cleanup and treatment levels. These uses of soil background require an understanding of the extent to which analytes of concern occur naturally in the soils. This report documents the results of sampling and analysis activities designed to characterize the composition of soil background at the Hanford Site, and to evaluate the feasibility for use as Sitewide background. The compositions of naturally occurring soils in the vadose Zone have been-determined for-nonradioactive inorganic and organic analytes and related physical properties. These results confirm that a Sitewide approach to the characterization of soil background is technically sound and is a viable alternative to the determination and use of numerous local or area backgrounds that yield inconsistent definitions of contamination. Sitewide soil background consists of several types of data and is appropriate for use in identifying contamination in all soils in the vadose zone on the Hanford Site. The natural concentrations of nearly every inorganic analyte extend to levels that exceed calculated health-based cleanup limits. The levels of most inorganic analytes, however, are well below these health-based limits. The highest measured background concentrations occur in three volumetrically minor soil types, the most important of which are topsoils adjacent to the Columbia River that are rich in organic carbon. No organic analyte levels above detection were found in any of the soil samples

Discretization of space and time: mass-energy relation, accelerating expansion of the Universe, Hubble constant

OpenAIRE

Roatta , Luca

2017-01-01

Assuming that space and time can only have discrete values, we obtain the expression of the gravitational potential energy that at large distance coincides with the Newtonian. In very precise circumstances it coincides with the relativistic mass-energy relation: this shows that the Universe is a black hole in which all bodies are subjected to an acceleration toward the border of the Universe itself. Since the Universe is a black hole with a fixed radius, we can obtain the density of the Unive...

γγ background of the Drell-Yan process

International Nuclear Information System (INIS)

Carimalo, C.; Kessler, P.; Parisi, J.

1978-01-01

Considering lepton pair production in nucleon-nucleon or nucleon-nucleus collisions, the mechanism of gamma-gamma materialization is compared with that of quark-antiquark annihilation (Drell-Yan process). The computed predictions show that, whereas the gamma-gamma background of the Drell-Yan process should be at most a few percent in present accelerator experiments, it might become more important for future proton-proton colliding beams of superhigh energies (such as in the ISABELLE project). Several different models of quark-parton distribution functions were used both to compute the Drell-Yan cross-section and to define the inelastic structure functions involved in the gamma-gamma effect; the latter was shown, however, to be relatively model-independent. Finally, the accuracy of the simplified procedure (double equivalent-photon method) applied to the gamma-gamma process was checked, using some data computed through a more precise method by Chen et al. It was shown that errors involved in the calculations should be less than 50%, which is of the order of model fluctuations

[Eating Disorders in Female High School Students: Educational and Migration Background, School-Related Stress and Performance-Orientated Classes].

Science.gov (United States)

Grüttner, M

2018-02-01

Many adolescents and young adults, especially young females, suffer from eating disorders or problematic nutrition behavior. Children and adolescents with migration background as well as from a lower social class are more likely to have eating disorders 1. Although schools are an important context in these age groups, there is a lack of scientific inquiry concerning the relationship between schooling and eating disorders. The present study investigates the relationship between performance-related stress at school and eating disorders while controlling for personnel and familial resources. Interview data on the 7 th grade high school students from the National Educational Panel Study (NEPS)* starting cohort 3 are used. The dependent variable is based on the SCOFF questionnaire. Logistic regressions are calculated using information from students and parents. Performance-related stress at school is operationalized by the negative deviation of realistic from idealistic educational aspirations (EA) and unfulfilled social expectations (SE), performance-oriented class climate is operationalized by students' perception of the performance-orientation of the teacher (PT) and the expectations of classmates (EC). The results point towards an increased risk of suffering from an eating disorder due to performance-related school stress (EA: AME: 0.18; p<0.001; SE: AME: 0.12; p<0.05) and performance-oriented class climate (PT: AME: 0.05; p<0.1; EC: AME: 0.15, p<0.01). They partly explain the relation between both migration background and educational background and eating disorders. In order to prevent eating disorders in female high school students, attention should be paid to performance-orientation experienced at school and in the social background, and improved individual support for disadvantaged students should be made available. © Georg Thieme Verlag KG Stuttgart · New York.

Transformations between inertial and linearly accelerated frames of reference

International Nuclear Information System (INIS)

Ashworth, D.G.

1983-01-01

Transformation equations between inertial and linearly accelerated frames of reference are derived and these transformation equations are shown to be compatible, where applicable, with those of special relativity. The physical nature of an accelerated frame of reference is unambiguously defined by means of an equation which relates the velocity of all points within the accelerated frame of reference to measurements made in an inertial frame of reference. (author)

Overview of CERN Technology Transfer Strategy and Accelerator-Related Activities

CERN Document Server

Chesta, E; Wuensch, W; Sgobba, S; Stora, T; Chiggiato, P; Taborelli, M

2013-01-01

CERN, the European Organization for Nuclear Research, is actively engaged in identifying technologies developed for its accelerator complex that could be profitably used by partner research organizations or commercial companies in applications with potentially high socio-economic impact beyond pure fundamental physics research. \

On statistical acceleration convergence of double sequences

Directory of Open Access Journals (Sweden)

Bipan Hazarika

2017-04-01

Full Text Available In this article the notion of statistical acceleration convergence of double sequences in Pringsheim's sense has been introduced. We prove the decompostion theorems for  statistical acceleration convergence of double sequences and some theorems related to that concept have been established using the four dimensional matrix transformations. We provided some examples, where the results of acceleration convergence fails to hold for the statistical cases.

Enhanced efficiency of plasma acceleration in the laser-induced cavity pressure acceleration scheme

International Nuclear Information System (INIS)

Badziak, J; Rosiński, M; Jabłoński, S; Pisarczyk, T; Chodukowski, T; Parys, P; Rączka, P; Krousky, E; Ullschmied, J; Liska, R; Kucharik, M

2015-01-01

Among various methods for the acceleration of dense plasmas the mechanism called laser-induced cavity pressure acceleration (LICPA) is capable of achieving the highest energetic efficiency. In the LICPA scheme, a projectile placed in a cavity is accelerated along a guiding channel by the laser-induced thermal plasma pressure or by the radiation pressure of an intense laser radiation trapped in the cavity. This arrangement leads to a significant enhancement of the hydrodynamic or electromagnetic forces driving the projectile, relative to standard laser acceleration schemes. The aim of this paper is to review recent experimental and numerical works on LICPA with the emphasis on the acceleration of heavy plasma macroparticles and dense ion beams. The main experimental part concerns the research carried out at the kilojoule sub-nanosecond PALS laser facility in Prague. Our measurements performed at this facility, supported by advanced two-dimensional hydrodynamic simulations, have demonstrated that the LICPA accelerator working in the long-pulse hydrodynamic regime can be a highly efficient tool for the acceleration of heavy plasma macroparticles to hyper-velocities and the generation of ultra-high-pressure (>100 Mbar) shocks through the collision of the macroparticle with a solid target. The energetic efficiency of the macroparticle acceleration and the shock generation has been found to be significantly higher than that for other laser-based methods used so far. Using particle-in-cell simulations it is shown that the LICPA scheme is highly efficient also in the short-pulse high-intensity regime and, in particular, may be used for production of intense ion beams of multi-MeV to GeV ion energies with the energetic efficiency of tens of per cent, much higher than for conventional laser acceleration schemes. (paper)

A Statistical Perspective on Highly Accelerated Testing

Energy Technology Data Exchange (ETDEWEB)

Thomas, Edward V. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2015-02-01

Highly accelerated life testing has been heavily promoted at Sandia (and elsewhere) as a means to rapidly identify product weaknesses caused by flaws in the product's design or manufacturing process. During product development, a small number of units are forced to fail at high stress. The failed units are then examined to determine the root causes of failure. The identification of the root causes of product failures exposed by highly accelerated life testing can instigate changes to the product's design and/or manufacturing process that result in a product with increased reliability. It is widely viewed that this qualitative use of highly accelerated life testing (often associated with the acronym HALT) can be useful. However, highly accelerated life testing has also been proposed as a quantitative means for "demonstrating" the reliability of a product where unreliability is associated with loss of margin via an identified and dominating failure mechanism. It is assumed that the dominant failure mechanism can be accelerated by changing the level of a stress factor that is assumed to be related to the dominant failure mode. In extreme cases, a minimal number of units (often from a pre-production lot) are subjected to a single highly accelerated stress relative to normal use. If no (or, sufficiently few) units fail at this high stress level, some might claim that a certain level of reliability has been demonstrated (relative to normal use conditions). Underlying this claim are assumptions regarding the level of knowledge associated with the relationship between the stress level and the probability of failure. The primary purpose of this document is to discuss (from a statistical perspective) the efficacy of using accelerated life testing protocols (and, in particular, "highly accelerated" protocols) to make quantitative inferences concerning the performance of a product (e.g., reliability) when in fact there is lack-of-knowledge and uncertainty concerning

Future HEP Accelerators: The US Perspective

Energy Technology Data Exchange (ETDEWEB)

Bhat, Pushpalatha [Fermilab; Shiltsev, Vladimir [Fermilab

2015-11-02

Accelerator technology has advanced tremendously since the introduction of accelerators in the 1930s, and particle accelerators have become indispensable instruments in high energy physics (HEP) research to probe Nature at smaller and smaller distances. At present, accelerator facilities can be classified into Energy Frontier colliders that enable direct discoveries and studies of high mass scale particles and Intensity Frontier accelerators for exploration of extremely rare processes, usually at relatively low energies. The near term strategies of the global energy frontier particle physics community are centered on fully exploiting the physics potential of the Large Hadron Collider (LHC) at CERN through its high-luminosity upgrade (HL-LHC), while the intensity frontier HEP research is focused on studies of neutrinos at the MW-scale beam power accelerator facilities, such as Fermilab Main Injector with the planned PIP-II SRF linac project. A number of next generation accelerator facilities have been proposed and are currently under consideration for the medium- and long-term future programs of accelerator-based HEP research. In this paper, we briefly review the post-LHC energy frontier options, both for lepton and hadron colliders in various regions of the world, as well as possible future intensity frontier accelerator facilities.

Hands-on Training Courses Using Research Reactors and Accelerators

International Nuclear Information System (INIS)

2014-01-01

The enhancement of nuclear science education and training in all Member States is of interest to the IAEA since many of these countries, particularly in the developing world, are building up and expanding their scientific and technological infrastructures. Unfortunately, most of these countries still lack sufficient numbers of well-educated and qualified nuclear specialists and technologists. This may arise from, amongst other things: a lack of candidates with sufficient educational background in nuclear science who would qualify to receive specialized training; a lack of institutions available for training nuclear science specialists; a lack of lecturers in nuclear related fields; and a lack of suitable educational and teaching materials. A related concern is the potential loss of valuable knowledge accumulated over many decades due to the ageing workforce. An imperative for Member States is to develop and offer suitable graduate and postgraduate academic programmes which combine study and project work so that students can attain a prerequisite level of knowledge, abilities and skills in their chosen subject area. In nearly all academic programmes, experimental work forms an essential and integral component of study to help students develop general and subject specific skills. Experimental laboratory courses and exercises can mean practical work in a conventional laboratory or an advanced facility with an operational particle accelerator or research reactor often accompanied by computer simulations and theoretical exercises. In this context, available or newly planned research reactors and particle accelerators should be seen as extremely important and indispensable components of nuclear science and technology curricula. Research reactors can demonstrate nuclear science and technology based on nuclear fission and the interaction of neutrons and photons with matter, while particle accelerators can demonstrate nuclear science and technology based on charged particle

An unofficial history of Japanese accelerators. Part four

International Nuclear Information System (INIS)

Inoue, Makoto

2005-01-01

History of accelerator development in Japan is overviewed for a period after 1980. In the first part, big accelerator projects including Japan-U.S. Science and Technology Cooperation Program, participation in SSC project, Big Hadron Project and RCNP ring cyclotron project are looked back. In the second part, the spread of small- and medium-scale accelerator utilization are overviewed. The third part is devoted to view the relation between the atomic energy research and accelerators. Organizations of Japanese accelerator society are surveyed in the last section. (K.Y.)

Airfoil flow instabilities induced by background flow oscillations

Energy Technology Data Exchange (ETDEWEB)

Selerowicz, W.C.; Szumowski, A.P. [Technical Univ. Warsaw (Poland)

2002-04-01

The effect of background flow oscillations on transonic airfoil (NACA 0012) flow was investigated experimentally. The oscillations were generated by means of a rotating plate placed downstream of the airfoil. Owing to oscillating chocking of the flow caused by the plate, the airfoil flow periodically accelerated and decelerated. This led to strong variations in the surface pressure and the airfoil loading. The results are presented for two angles of attack, {alpha}=4 and {alpha}=8.5 , which correspond to the attached and separated steady airfoil flows, respectively. (orig.)

Childhood cancers in the UK and their relation to background radiation

International Nuclear Information System (INIS)

Kneale, G.W.; Stewart, A.M.

1987-01-01

This chapter shows the results of including two independent data sets in a study of several factors with cancer associations including background radiation. One data set came from the Oxford Survey of Childhood Cancers (OSCC); the other from the National Radiological Protection Board (NRPB) and findings are compatible with background radiation being the single most important cause of juvenile neoplasms. It also emerged that these neoplasms have a strongly clustered distribution. No obvious cause of clusters was found, but they had associations with prenatal and postnatal illnesses as well as background radiation. Therefore, since there is mounting sensitivity to infections during the latent phase of leukaemia, cancer clusters might be the result of competing causes of death having an epidemic distribution. The findings as a whole are compatible with all man-made additions to background (including leakages of radioactivity from a reprocessing plant) adding to risk of an early cancer death. Proof that certain leukaemia clusters in the vicinity of two reprocessing plants were caused in this way must await collection of data. (author)

A definition of background independence

International Nuclear Information System (INIS)

Gryb, Sean

2010-01-01

We propose a definition for background (in)/dependence in dynamical theories of the evolution of configurations that have a continuous symmetry and test this definition on particle models and on gravity. Our definition draws from Barbour's best matching framework developed for the purpose of implementing spatial and temporal relationalism. Among other interesting theories, general relativity can be derived within this framework in novel ways. We study the detailed canonical structure of a wide range of best matching theories and show that their actions must have a local gauge symmetry. When gauge theory is derived in this way, we obtain at the same time a conceptual framework for distinguishing between background-dependent and -independent theories. Gauge invariant observables satisfying Kuchar's criterion are identified and, in simple cases, explicitly computed. We propose a procedure for inserting a global background time into temporally relational theories. Interestingly, using this procedure in general relativity leads to unimodular gravity.

Dispersion relation and electron acceleration in the combined circular and elliptical metallic-dielectric waveguide filled by plasma

Science.gov (United States)

Abdoli-Arani, A.; Montazeri, M. M.

2018-04-01

Two special types of metallic waveguide having dielectric cladding and plasma core including the combined circular and elliptical structure are studied. Longitudinal and transverse field components in the different regions are obtained. Applying the boundary conditions, dispersion relations of the electromagnetic waves in the structures are obtained and then plotted. The acceleration of an injected external relativistic electron in the considered waveguides is studied. The obtained differential equations related to electron motion are solved by the fourth-order Runge-Kutta method. Numerical computations are made, and the results are graphically presented.

High power electron accelerators for flue gas treatment

International Nuclear Information System (INIS)

Zimek, Z.

2011-01-01

Flue gas treatment process based on electron beam application for SO 2 and NO x removal was successfully demonstrated in number of laboratories, pilot plants and industrial demonstration facilities. The industrial scale application of an electron beam process for flue gas treatment requires accelerators modules with a beam power 100-500 kW and electron energy range 0.8-1.5 MeV. The most important accelerator parameters for successful flue gas radiation technology implementation are related to accelerator reliability/availability, electrical efficiency and accelerator price. Experience gained in high power accelerators exploitation in flue gas treatment industrial demonstration facility was described and high power accelerator constructions have been reviewed. (author)

Examination of background contamination levels for gas counting and AMS target preparation in Trondheim

DEFF Research Database (Denmark)

Gulliksen, S.; Thomsen, M.S.

1992-01-01

conventional gas proportional counting (GPC) system. We have also studied contamination levels of our target preparation for C-14 accelerator mass spectrometry (AMS) dating in Uppsala. A significant lower background is obtained for Icelandic double spar than for marbles, probably due to a crystal structure...

Special scientific programme on use of high energy accelerators for transmutation of actinides and power production

International Nuclear Information System (INIS)

1994-09-01

Various techniques for the transmutation of radioactive waste through the use of high energy accelerators are reviewed and discussed. In particular, the present publication contains presentations on (i) requirements and the technical possibilities for the transmutation of long-lived radionuclides (background paper); (ii) high energy particle accelerators for bulk transformation of elements and energy generation; (iii) the resolution of nuclear energy issues using accelerator-driven technology; (iv) the use of proton accelerators for the transmutation of actinides and power production; (v) the coupling of an accelerator to a subcritical fission reactor (with a view on its potential impact on waste transmutation); (vi) research and development of accelerator-based transmutation technology at JAERI (Japan); and (vii) questions and problems with regard to accelerator-driven nuclear power and transmutation facilities. Refs, figs and tabs

Background to Dark Matter Searches from Galactic Cosmic Rays

CERN Multimedia

CERN. Geneva

2015-01-01

Just as searches for BSM physics at the LHC necessitate a careful audit of SM backgrounds, the search for signals of dark matter in cosmic rays must contend with production of secondaries like e+ and pbar through cosmic ray propagation in the Galaxy. The theoretical framework for calculating this has however not been directly calibrated at the high energies being explored by AMS-02 and there may be surprises in store. In particular a nearby source where cosmic rays are being accelerated stochastically can naturally generate a e+ fraction rising with energy as is observed. The test of this is the expected correlated rise in other secondary/primary ratios e.g. B/C and pbar/p. Such a nearby cosmic accelerator should also be detectable through the concomitant flux of neutrinos and its discovery would be (nearly!) as exciting as that of dark matter.

Laser-propelled ram accelerator

Energy Technology Data Exchange (ETDEWEB)

Sasoh, A. [Tohoku Univ., Sendai (Japan). Inst. of Fluid Science

2000-11-01

The concept of 'laser-propelled ram accelerator (L-RAMAC)' is proposed. Theoretically it is capable of achieving a higher launch speed than that by a chemical ram accelerator because a higher specific energy can be input to the propellant gas. The laser beam is supplied through the muzzle, focused as an annulus behind the base of the projectile. The performance of L-RAMAC is analized based on generalized Rankine-Hugoniot relations, suggesting that a superorbital muzzle speed is achievable out of this device. (orig.)

Precise muon drift tube detectors for high background rate conditions

CERN Document Server

Engl, Albert; Dünnweber, Wolfgang

The muon spectrometer of the ATLAS-experiment at the Large H adron Collider consists of drift tube chambers, which provide the precise m easurement of trajec- tories of traversing muons. In order to determine the moment um of the muons with high precision, the measurement of the position of the m uon in a single tube has to be more accurate than σ ≤ 100 m. The large cross section of proton-proton-collisions and th e high luminosity of the accelerator cause relevant background of neutrons and γ s in the muon spectrome- ter. During the next decade a luminosity upgrade [1] to 5 10 34 cm − 2 s − 1 is planned, which will increase the background counting rates consider ably. In this context this work deals with the further development of the existing drift chamber tech- nology to provide the required accuracy of the position meas urement under high background conditions. Two approaches of improving the dri ft tube chambers are described: • In regions of moderate background rates a faster and more lin ear ...

Background intercomparison with escape-suppressed germanium detectors in underground mines

Energy Technology Data Exchange (ETDEWEB)

Szuecs, Tamas; Bemmerer, Daniel [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden (Germany)

2014-07-01

A key requirement for underground nuclear astrophysics experiments is the very low background level in germanium detectors underground. The reference for these purposes is the world's so far only underground accelerator laboratory for nuclear astrophysics, LUNA. LUNA is located deep underground in the Gran Sasso laboratory in Italy, shielded from cosmic rays by 1400 m of rock. The background at LUNA was studied in detail using an escape-suppressed Clover-type HPGe detector. Exactly the same detector was subsequently transported to the Felsenkeller underground laboratory in Dresden, shielded by 45 m of rock, and the background was shown to be only a factor of three higher than at LUNA when comparing the escape-suppressed spectra, with interesting consequences for underground nuclear astrophysics. As the next step of a systematic study of the effects of a combination of active and passive shielding on the cosmic ray induced background, this detector is now being brought to the ''Reiche Zeche'' mine in Freiberg/Sachsen, shielded by 150 m of rock. The data from the Freiberg measurement are shown and discussed.

Implementation of Hardware Accelerators on Zynq

DEFF Research Database (Denmark)

Toft, Jakob Kenn

of the ARM Cortex-9 processor featured on the Zynq SoC, with regard to execution time, power dissipation and energy consumption. The implementation of the hardware accelerators were successful. Use of the Monte Carlo processor resulted in a significant increase in performance. The Telco hardware accelerator......In the recent years it has become obvious that the performance of general purpose processors are having trouble meeting the requirements of high performance computing applications of today. This is partly due to the relatively high power consumption, compared to the performance, of general purpose...... processors, which has made hardware accelerators an essential part of several datacentres and the worlds fastest super-computers. In this work, two different hardware accelerators were implemented on a Xilinx Zynq SoC platform mounted on the ZedBoard platform. The two accelerators are based on two different...

Materials considerations for molten salt accelerator-based plutonium conversion systems

International Nuclear Information System (INIS)

DiStefano, J.R.; DeVan, J.H.; Keiser, J.R.; Klueh, R.L.; Eatherly, W.P.

1995-03-01

Accelerator-driven transmutation technology (ADTT) refers to a concept for a system that uses a blanket assembly driven by a source of neutrons produced when high-energy protons from an accelerator strike a heavy metal target. One application for such a system is called Accelerator-Based Plutonium Conversion, or ABC. Currently, the version of this concept being proposed by the Los Alamos National Laboratory features a liquid lead target material and a blanket fuel of molten fluorides that contain plutonium. Thus, the materials to be used in such a system must have, in addition to adequate mechanical strength, corrosion resistance to molten lead, corrosion resistance to molten fluoride salts, and resistance to radiation damage. In this report the corrosion properties of liquid lead and the LiF-BeF 2 molten salt system are reviewed in the context of candidate materials for the above application. Background information has been drawn from extensive past studies. The system operating temperature, type of protective environment, and oxidation potential of the salt are shown to be critical design considerations. Factors such as the generation of fission products and transmutation of salt components also significantly affect corrosion behavior, and procedures for inhibiting their effects are discussed. In view of the potential for extreme conditions relative to neutron fluxes and energies that can occur in an ADTT, a knowledge of radiation effects is a most important factor. Present information for potential materials selections is summarized

Materials considerations for molten salt accelerator-based plutonium conversion systems

International Nuclear Information System (INIS)

DiStefano, J.R.; DeVan, J.H.; Keiser, J.R.; Klueh, R.L.; Eatherly, W.P.

1995-02-01

Accelerator-driven transmutation technology (ADTT) refers to a concept for a system that uses a blanket assembly driven by a source of neutrons produced when high-energy protons from an accelerator strike a heavy metal target. One application for such a system is called Accelerator-Based Plutonium Conversion, or ABC. Currently, the version of this concept being proposed by the Los Alamos National Laboratory features a liquid lead target material and a blanket fuel of molten fluorides that contain plutonium. Thus, the materials to be used in such a system must have, in addition to adequate mechanical strength, corrosion resistance to molten lead, corrosion resistance to molten fluoride salts, and resistance to radiation damage. In this report the corrosion properties of liquid lead and the LiF-BeF 2 molten salt system are reviewed in the context of candidate materials for the above application. Background information has been drawn from extensive past studies. The system operating temperature, type of protective environment, and oxidation potential of the salt are shown to be critical design considerations. Factors such as the generation of fission products and transmutation of salt components also significantly affect corrosion behavior, and procedures for inhibiting their effects are discussed. In view of the potential for extreme conditions relative to neutron fluxes and energies that can occur in an ADTT, a knowledge of radiation effects is a most important factor. Present information for potential materials selections is summarized

A statistical comparison of accelerated concrete testing methods

OpenAIRE

Denny Meyer

1997-01-01

Accelerated curing results, obtained after only 24 hours, are used to predict the 28 day strength of concrete. Various accelerated curing methods are available. Two of these methods are compared in relation to the accuracy of their predictions and the stability of the relationship between their 24 hour and 28 day concrete strength. The results suggest that Warm Water accelerated curing is preferable to Hot Water accelerated curing of concrete. In addition, some other methods for improving the...

Linear Accelerator Stereotactic Radiosurgery of Central Nervous System Arteriovenous Malformations: A 15-Year Analysis of Outcome-Related Factors in a Single Tertiary Center.

Science.gov (United States)

Thenier-Villa, José Luis; Galárraga-Campoverde, Raúl Alejandro; Martínez Rolán, Rosa María; De La Lama Zaragoza, Adolfo Ramón; Martínez Cueto, Pedro; Muñoz Garzón, Víctor; Salgado Fernández, Manuel; Conde Alonso, Cesáreo

2017-07-01

Linear accelerator stereotactic radiosurgery is one of the modalities available for the treatment of central nervous system arteriovenous malformations (AVMs). The aim of this study was to describe our 15-year experience with this technique in a single tertiary center and the analysis of outcome-related factors. From 1998 to 2013, 195 patients were treated with linear accelerator-based radiosurgery; we conducted a retrospective study collecting patient- and AVM-related variables. Treatment outcomes were obliteration, posttreatment hemorrhage, symptomatic radiation-induced changes, and 3-year neurologic status. We also analyzed prognostic factors of each outcome and predictability analysis of 5 scales: Spetzler-Martin grade, Lawton-Young supplementary and Lawton combined scores, radiosurgery-based AVM score, Virginia Radiosurgery AVM Scale, and Heidelberg score. Overall obliteration rate was 81%. Nidus diameter and venous drainage were predictive of obliteration (P linear accelerator-based radiosurgery is a useful, valid, effective, and safe modality for treatment of brain AVMs. Copyright © 2017 Elsevier Inc. All rights reserved.

Acceleration of a high-current single bunch in a linear accelerator

International Nuclear Information System (INIS)

Takeda, Seishi

1984-01-01

Some problems associated with the feasibility of an electron-positron linear collider with colliding energy of about 1x1 TeV are discussed. The first problem is related to the generation of high-current single bunch. A quasi-relativistic electron beam from an electron gun is injected into one bucket of the accelerating fields, in opposition to the longitudinal defocusing due to the space-charge effect. For generating a high-current single bunch, the beam bunching by means of the velocity modulation with a subharmonic prebuncher (SHPB) is indispensable. Three existing second generation single bunch electron linear accelerators (SLC, ANL and ISLR-Osaka Univ.) are briefly described. The results of the simulation of subharmonic-bunching is also reported. The second problem is associated with the physics of accelerating high-current single bunch. The longitudinal and transverse wake fields generated by a bunch-cavity interaction and the energy spread of the single bunch are analyzed and discussed. (Aoki, K.)

Plasma accelerators

International Nuclear Information System (INIS)

Bingham, R.; Angelis, U. de; Johnston, T.W.

1991-01-01

Recently attention has focused on charged particle acceleration in a plasma by a fast, large amplitude, longitudinal electron plasma wave. The plasma beat wave and plasma wakefield accelerators are two efficient ways of producing ultra-high accelerating gradients. Starting with the plasma beat wave accelerator (PBWA) and laser wakefield accelerator (LWFA) schemes and the plasma wakefield accelerator (PWFA) steady progress has been made in theory, simulations and experiments. Computations are presented for the study of LWFA. (author)

ORNL pellet acceleration program

International Nuclear Information System (INIS)

Foster, C.A.; Milora, S.L.

1978-01-01

The Oak Ridge National Laboratory (ORNL) pellet fueling program is centered around developing equipment to accelerate large pellets of solidified hydrogen to high speeds. This equipment will be used to experimentally determine pellet-plasma interaction physics on contemporary tokamaks. The pellet experiments performed on the Oak Ridge Tokamak (ORMAK) indicated that much larger, faster pellets would be advantageous. In order to produce and accelerate pellets of the order of 1 to 6 mm in diameter, two apparatuses have been designed and are being constructed. The first will make H 2 pellets by extruding a filament of hydrogen and mechanically chopping it into pellets. The pellets formed will be mechanically accelerated with a high speed arbor to a speed of 950 m/sec. This technique may be extended to speeds up to 5000 m/sec, which makes it a prime candidate for a reactor fueling device. In the second technique, a hydrogen pellet will be formed, loaded into a miniature rifle, and accelerated by means of high pressure hydrogen gas. This technique should be capable of speeds of the order of 1000 m/sec. While this technique does not offer the high performance of the mechanical accelerator, its relative simplicity makes it attractive for near-term experiments

Conformal symmetries of FRW accelerating cosmologies

International Nuclear Information System (INIS)

Kehagias, A.; Riotto, A.

2014-01-01

We show that any accelerating Friedmann–Robertson–Walker (FRW) cosmology with equation of state w<−1/3 (and therefore not only a de Sitter stage with w=−1) exhibits three-dimensional conformal symmetry on future constant-time hypersurfaces if the bulk theory is invariant under bulk conformal Killing vectors. We also offer an alternative derivation of this result in terms of conformal Killing vectors and show that long wavelength comoving curvature perturbations of the perturbed FRW metric are just conformal Killing motions of the FRW background. We then extend the boundary conformal symmetry to the bulk for accelerating cosmologies. Our findings indicate that one can easily generate perturbations of scalar fields which are not only scale invariant, but also fully conformally invariant on super-Hubble scales. Measuring a scale-invariant power spectrum for the cosmological perturbation does not automatically imply that the universe went through a de Sitter stage

Acceleration of electrons and supplementary ionization during parametrical plasma heating

International Nuclear Information System (INIS)

Grach, S.M.; Mityakov, N.A.; Trakhtengerts, V.Yu.; AN SSSR, Gor'kij. Inst. Prikladnoj Fiziki)

1986-01-01

Acceleration of electrons by plasma waves in partially ionized plasma is considered with provision for the effects of turbulent scattering and formation of secondary electrons, which are produced in the process of electron shock ionization. It is shown that the avalanche density growth of electrons accelerated up to 1-2 ionization potential (instability) takes place beginning from some critical density of plasma waves. Density of fast electrons is found out along with plasma wave energy density at the stage of instability saturation. Additional concentration of a background plasma, which manifests itself due to ionization, is evaluated

Attrition and success rates of accelerated students in nursing courses: a systematic review

OpenAIRE

Doggrell, Sheila Anne; Schaffer, Sally

2016-01-01

Background There is a comprehensive literature on the academic outcomes (attrition and success) of students in traditional/baccalaureate nursing programs, but much less is known about the academic outcomes of students in accelerated nursing programs. The aim of this systematic review is to report on the attrition and success rates (either internal examination or NCLEX-RN) of accelerated students, compared to traditional students. Methods For the systematic review, the databases (Pubmed, Cinah...

Multi-Mode Cavity Accelerator Structure

Energy Technology Data Exchange (ETDEWEB)

Jiang, Yong [Yale Univ., New Haven, CT (United States); Hirshfield, Jay Leonard [Omega-P R& D, Inc., New Haven, CT (United States)

2016-11-10

This project aimed to develop a prototype for a novel accelerator structure comprising coupled cavities that are tuned to support modes with harmonically-related eigenfrequencies, with the goal of reaching an acceleration gradient >200 MeV/m and a breakdown rate <10^-7/pulse/meter. Phase I involved computations, design, and preliminary engineering of a prototype multi-harmonic cavity accelerator structure; plus tests of a bimodal cavity. A computational procedure was used to design an optimized profile for a bimodal cavity with high shunt impedance and low surface fields to maximize the reduction in temperature rise ΔT. This cavity supports the TM010 mode and its 2nd harmonic TM011 mode. Its fundamental frequency is at 12 GHz, to benchmark against the empirical criteria proposed within the worldwide High Gradient collaboration for X-band copper structures; namely, a surface electric field E_sur^max< 260 MV/m and pulsed surface heating ΔT^max< 56 °K. With optimized geometry, amplitude and relative phase of the two modes, reductions are found in surface pulsed heating, modified Poynting vector, and total RF power—as compared with operation at the same acceleration gradient using only the fundamental mode.

Multi-Mode Cavity Accelerator Structure

International Nuclear Information System (INIS)

Jiang, Yong; Hirshfield, Jay Leonard

2016-01-01

This project aimed to develop a prototype for a novel accelerator structure comprising coupled cavities that are tuned to support modes with harmonically-related eigenfrequencies, with the goal of reaching an acceleration gradient >200 MeV/m and a breakdown rate <10"-"7/pulse/meter. Phase I involved computations, design, and preliminary engineering of a prototype multi-harmonic cavity accelerator structure; plus tests of a bimodal cavity. A computational procedure was used to design an optimized profile for a bimodal cavity with high shunt impedance and low surface fields to maximize the reduction in temperature rise Δ T. This cavity supports the TM010 mode and its 2nd harmonic TM011 mode. Its fundamental frequency is at 12 GHz, to benchmark against the empirical criteria proposed within the worldwide High Gradient collaboration for X-band copper structures; namely, a surface electric field E_s_u_r"m"a"x< 260 MV/m and pulsed surface heating Δ T"m"a"x< 56 °K. With optimized geometry, amplitude and relative phase of the two modes, reductions are found in surface pulsed heating, modified Poynting vector, and total RF power - as compared with operation at the same acceleration gradient using only the fundamental mode.

APT related papers presented at the 1997 particle accelerator conference, Vancouver, May 12--16, 1997

International Nuclear Information System (INIS)

Lawrence, G.

1997-07-01

Tritium is essential for the US nuclear weapons to function, but because it is radioactive with a half-life of 12.3 years, the supply must be periodically replenished. Presently, only reactor or accelerator systems can be used to produce tritium. This report is a compilation of 31 papers given at the 1997 Particle Accelerator Conference which dealt with the accelerator production of tritium. The papers are grouped into two categories, invited and contributed

APT related papers presented at the 1997 particle accelerator conference, Vancouver, May 12--16, 1997

Energy Technology Data Exchange (ETDEWEB)

Lawrence, G. [comp.

1997-07-01

Tritium is essential for the US nuclear weapons to function, but because it is radioactive with a half-life of 12.3 years, the supply must be periodically replenished. Presently, only reactor or accelerator systems can be used to produce tritium. This report is a compilation of 31 papers given at the 1997 Particle Accelerator Conference which dealt with the accelerator production of tritium. The papers are grouped into two categories, invited and contributed.

High power electron accelerators for flue gas treatment

Energy Technology Data Exchange (ETDEWEB)

Zimek, Z. [Institute of Nuclear Chemistry and Technology, Warsaw (Poland)

2011-07-01

Flue gas treatment process based on electron beam application for SO{sub 2} and NO{sub x} removal was successfully demonstrated in number of laboratories, pilot plants and industrial demonstration facilities. The industrial scale application of an electron beam process for flue gas treatment requires accelerators modules with a beam power 100-500 kW and electron energy range 0.8-1.5 MeV. The most important accelerator parameters for successful flue gas radiation technology implementation are related to accelerator reliability/availability, electrical efficiency and accelerator price. Experience gained in high power accelerators exploitation in flue gas treatment industrial demonstration facility was described and high power accelerator constructions have been reviewed. (author)

Next generation redshift surveys and the origin of cosmic acceleration

International Nuclear Information System (INIS)

Acquaviva, Viviana; Hajian, Amir; Spergel, David N.; Das, Sudeep

2008-01-01

Cosmologists are exploring two possible sets of explanations for the remarkable observation of cosmic acceleration: dark energy fills space or general relativity fails on cosmological scales. We define a null test parameter ε(k,a)≡Ω m -γ dlnD/dlna-1, where a is the scale factor, D is the growth rate of structure, Ω m (a) is the matter density parameter, and γ is a simple function of redshift. We show that it can be expressed entirely in terms of the bias factor, b(a), measured from cross correlations with cosmic microwave background (CMB) lensing, and the amplitude of redshift-space distortions, β(k,a). Measurements of the CMB power spectrum determine Ω m0 H 0 2 . If dark energy within general relativity is the solution to the cosmic acceleration problem, then the logarithmic growth rate of structure dlnD/dlna=Ω m γ . Thus, ε(k,a)=0 on linear scales to better than 1%. We show that in the class of modified gravity models known as f(R), the growth rate has a different dependence on scale and redshift. By combining measurements of the amplitude of β and of the bias, b, redshift surveys will be able to determine the logarithmic growth rate as a function of scale and redshift. We estimate the predicted sensitivity of the proposed SDSS III (BOSS) survey and the proposed ADEPT mission and find that they will test structure growth in general relativity to the percent level.

AI systems approach in particle accelerators

International Nuclear Information System (INIS)

Kataria, S.K.; Bhagwat, P.V.; Kori, S.A.

1992-01-01

The large particle accelerators machines like pelletron accelerator at Tata Institute of Fundamental Research (T.I.F.R) have several levels of controls with operators responsible for overall global control decisions and closed loop feedback controllers for relatively small subsystems of the machines. As the accelerator machines are becoming more complicated and the requirements more stringent, there is a need to provide the operators with an artificial intelligence (AI) system to aid in the tuning the machine and in failure diagnosis. There are few major areas in the pelletron operation, which can be done more efficiently using AI systems approach so that useful beam is available for much more time: 1) Accelerator Conditioning, 2) Accelerator Tuning, and 3) Maintaining the Tune beams. The feasibility study for using expert system for above areas and also for safety evaluation of the various subsystems is carried out. (author). 10 refs., 4 figs

Cosmic-ray acceleration at stellar wind terminal shocks

International Nuclear Information System (INIS)

Webb, G.M.; Forman, M.A.; Axford, W.I.

1985-01-01

Steady-state, spherically symmetric, analytic solutions of the cosmic-ray transport equations, applicable to the problem of acceleration of cosmic rays at the terminal shock to a stellar wind, are studied. The spectra, gradients, and flow patterns of particle modulated and accelerated by the stellar wind and shock are investigated by means of monoenergetic-source solutions at finite radius, as well as solutions with monoenergetic and power-law Galactic spectra. The solutions obtained apply in the test particle limit in which the cosmic rays do not modify the background flow. The solutions show a characteristic power-law momentum spectrum for accelerated particles and a more complex spectrum of particles that are decelerated in the stellar wind. The power-law spectral index depends on the compression ratio of the shock and on the modulation parameters characterizing propagation conditions in the upstream and downstream regions of the shock. Solutions of the transport equations for the total density N (integrated over all energies), pressure P/sub c/, and energy flux F/sub c/ of Galactic cosmic rays interacting with a stellar wind and shock are also studied. The density N(r) increases with radius r, and for strong shocks with large enough modulation parameters, there may be a significant enhancement of the pressure of weakly relativistic particles near the shock compared to the cosmic-ray background pressure P/sub infinity/. The emergent energy flux at infinity is of the order of 4π R 2 V 1 P/sub infinity/ (V 1 is wind velocity upstream of the shock, R is shock radius)

First muon acceleration using a radio-frequency accelerator

Directory of Open Access Journals (Sweden)

S. Bae

2018-05-01

Full Text Available Muons have been accelerated by using a radio-frequency accelerator for the first time. Negative muonium atoms (Mu^{-}, which are bound states of positive muons (μ^{+} and two electrons, are generated from μ^{+}’s through the electron capture process in an aluminum degrader. The generated Mu^{-}’s are initially electrostatically accelerated and injected into a radio-frequency quadrupole linac (RFQ. In the RFQ, the Mu^{-}’s are accelerated to 89 keV. The accelerated Mu^{-}’s are identified by momentum measurement and time of flight. This compact muon linac opens the door to various muon accelerator applications including particle physics measurements and the construction of a transmission muon microscope.

From coach to colleague: adjusting pedagogical approaches and attitudes in accelerated nursing programs.

Science.gov (United States)

Bowie, Bonnie H; Carr, Katherine Camacho

2013-01-01

Accelerated nursing programs are an innovative approach to training nurses and advanced practice nurses that are growing steadily in number and popularity. Although there is ample evidence to show that these programs have good outcomes, acceptance by both faculty and nurses in the community remains low. This article gives a description of the accelerated nursing student, which provides some insight as to why this student is both a challenge and a joy to mentor. In addition, an overview of pedagogical approaches that may be helpful in teaching this bright group of accelerated nursing students is provided. Accelerated nursing students enrich the nursing profession with the myriad of skills and varied backgrounds they bring to nursing. As professionals, mentors, and educators, we need to not only embrace accelerated students but also be advocates and mentors for them as they assimilate into our profession. Copyright © 2013 Elsevier Inc. All rights reserved.

Portuguese Coaches' Perceptions of and Preferences for Knowledge Sources Related to their Professional Background.

Science.gov (United States)

Mesquita, Isabel; Isidro, Sofia; Rosado, António

2010-01-01

The purpose of this study was to analyse Portuguese coaches' perceptions of, and preferences for, knowledge sources as related to professional background; namely academic education level, coach education level and coaching experience. The study's participants comprised 336 Portuguese coaches from twenty-two sports. A questionnaire was used to identify coaches' demographic characteristics and representations about their preferred sources of coaching knowledge. MANOVA using Tukey's HSD test was used to compare groups. The results highlighted that coaches perceived that coaching knowledge is built from a broad range of sources from personal coaching and playing experiences to more explicit formal, informal and non-formal learning situations. Results indicated that the coaches ascribed more importance to experiential sources such as working with experts, learning by doing, interacting with peer coaches and attending informal seminars and clinics, than to the formal learning situations provided by the national coaching certification programs. Differences, however, were found in that coaches who had a greater background within higher education (physical) and sport valued informal and non-formal learning sources more than did coaches who were defined as not coming from an academic background. The findings point to the importance of developing new learning, experientially-based, opportunities within the Portuguese context, where curricula content continues to be delivered via didactic means. Key pointsCoaches recognized that learning is obtained from a broad range of sources of coaching knowledge and each source has a particular role in the development of a coach.Experiential guided sources reached more importance to coaches as working with experts, learning by doing, attending seminars/clinics outside of the formal system and interaction with peers were the most acknowledged.The only source that is related to formal learning, national certification programs, was

Portuguese Coaches’ Perceptions of and Preferences for Knowledge Sources Related to their Professional Background

Science.gov (United States)

Mesquita, Isabel; Isidro, Sofia; Rosado, António

2010-01-01

The purpose of this study was to analyse Portuguese coaches’ perceptions of, and preferences for, knowledge sources as related to professional background; namely academic education level, coach education level and coaching experience. The study’s participants comprised 336 Portuguese coaches from twenty-two sports. A questionnaire was used to identify coaches’ demographic characteristics and representations about their preferred sources of coaching knowledge. MANOVA using Tukey’s HSD test was used to compare groups. The results highlighted that coaches perceived that coaching knowledge is built from a broad range of sources from personal coaching and playing experiences to more explicit formal, informal and non-formal learning situations. Results indicated that the coaches ascribed more importance to experiential sources such as working with experts, learning by doing, interacting with peer coaches and attending informal seminars and clinics, than to the formal learning situations provided by the national coaching certification programs. Differences, however, were found in that coaches who had a greater background within higher education (physical) and sport valued informal and non-formal learning sources more than did coaches who were defined as not coming from an academic background. The findings point to the importance of developing new learning, experientially-based, opportunities within the Portuguese context, where curricula content continues to be delivered via didactic means. Key points Coaches recognized that learning is obtained from a broad range of sources of coaching knowledge and each source has a particular role in the development of a coach. Experiential guided sources reached more importance to coaches as working with experts, learning by doing, attending seminars/clinics outside of the formal system and interaction with peers were the most acknowledged. The only source that is related to formal learning, national certification programs

Accelerator development

International Nuclear Information System (INIS)

Anon.

1975-01-01

Because the use of accelerated heavy ions would provide many opportunities for new and important studies in nuclear physics and nuclear chemistry, as well as other disciplines, both the Chemistry and Physics Divisions are supporting the development of a heavy-ion accelerator. The design of greatest current interest includes a tandem accelerator with a terminal voltage of approximately 25 MV injecting into a linear accelerator with rf superconducting resonators. This combined accelerator facility would be capable of accelerating ions of masses ranging over the entire periodic table to an energy corresponding to approximately 10 MeV/nucleon. This approach, as compared to other concepts, has the advantages of lower construction costs, lower operating power, 100 percent duty factor, and high beam quality (good energy resolution, good timing resolution, small beam size, and small beam divergence). The included sections describe the concept of the proposed heavy-ion accelerator, and the development program aiming at: (1) investigation of the individual questions concerning the superconducting accelerating resonators; (2) construction and testing of prototype accelerator systems; and (3) search for economical solutions to engineering problems. (U.S.)

Accelerator Technology: Geodesy and Alignment for Particle Accelerators

CERN Document Server

Missiaen, D

2013-01-01

This document is part of Subvolume C 'Accelerators and Colliders' of Volume 21 'Elementary Particles' of Landolt-Börnstein - Group I 'Elementary Particles, Nuclei and Atoms'. It contains the the Section '8.9 Geodesy and Alignment for Particle Accelerators' of the Chapter '8 Accelerator Technology' with the content: 8.9 Geodesy and Alignment for Particle Accelerators 8.9.1 Introduction 8.9.2 Reference and Co-ordinate Systems 8.9.3 Definition of the Beam Line on the Accelerator Site 8.9.4 Geodetic Network 8.9.5 Tunnel Preliminary Works 8.9.6 The Alignment References 8.9.7 Alignment of Accelerator Components 8.9.8 Permanent Monitoring and Remote Alignment of Low Beta Quadrupoles 8.9.9 Alignment of Detector Components

Recent trends in particle accelerator radiation safety

International Nuclear Information System (INIS)

Ohnesorge, W.F.; Butler, H.M.

1974-01-01

The use of particle accelerators in applied and research activities continues to expand, bringing new machines with higher energy and current capabilities which create radiation safety problems not commonly encountered before. An overview is given of these increased ionizing radiation hazards, along with a discussion of some of the new techniques required in evaluating and controlling them. A computer search of the literature provided a relatively comprehensive list of publications describing accelerator radiation safety problems and related subjects

28 CFR 23.2 - Background.

Science.gov (United States)

2010-07-01

... 28 Judicial Administration 1 2010-07-01 2010-07-01 false Background. 23.2 Section 23.2 Judicial Administration DEPARTMENT OF JUSTICE CRIMINAL INTELLIGENCE SYSTEMS OPERATING POLICIES § 23.2 Background. It is... potential threats to the privacy of individuals to whom such data relates, policy guidelines for Federally...

Relation of EEG alpha background to cognitive fuction, brain atrophy, and cerebral metabolism in Down's syndrome. Age-specific changes

International Nuclear Information System (INIS)

Devinsky, O.; Sato, S.; Conwit, R.A.; Schapiro, M.B.

1990-01-01

We studied 19 young adults (19 to 37 years old) and 9 older patients (42 to 66 years old) with Down's syndrome (DS) and a control group of 13 healthy adults (22 to 38 years old) to investigate the relation of electroencephalographic (EEG) alpha background to cognitive function and cerebral metabolism. Four of the older patients with DS had a history of mental deterioration, disorientation, and memory loss and were demented. Patients and control subjects had EEGs, psychometric testing, quantitative computed tomography, and positron emission tomography with fludeoxyglucose F 18. A blinded reader classified the EEGs into two groups--those with normal alpha background or those with abnormal background. All the control subjects, the 13 young adult patients with DS, and the 5 older patients with DS had normal EEG backgrounds. In comparison with the age-matched patients with DS with normal alpha background, older patients with DS with decreased alpha background had dementia, fewer visuospatial skills, decreased attention span, larger third ventricles, and a global decrease in cerebral glucose utilization with parietal hypometabolism. In the young patients with DS, the EEG background did not correlate with psychometric or positron emission tomographic findings, but the third ventricles were significantly larger in those with abnormal EEG background. The young patients with DS, with or without normal EEG background, had positron emission tomographic findings similar to those of the control subjects. The mechanism underlying the abnormal EEG background may be the neuropathologic changes of Alzheimer's disease in older patients with DS and may be cerebral immaturity in younger patients with DS

Measurement of gravitational acceleration of antimatter

International Nuclear Information System (INIS)

Rouhani, S.

1989-12-01

The minute yet effective impact of gravitational potential in the central region of a long tube magnetic container of non-neutral plasmas can be utilized for the measurement of the gravitational acceleration of antimatter particles. The slight change in distribution of plasma particles along the gravitational field affects the internal electric field of the plasma, which in turn affects the frequency of the magnetron motion of its particles. Thus, a rather straightforward relation is established between the gravitational acceleration of the particles and their magnetron frequencies, which is measurable directly, determining the value of the gravitational acceleration. (author). 7 refs, 3 figs

Are Principal Background and School Processes Related to Teacher Job Satisfaction? A Multilevel Study Using Schools and Staffing Survey 2003-04

Science.gov (United States)

Shen, Jianping; Leslie, Jeffrey M.; Spybrook, Jessaca K.; Ma, Xin

2012-01-01

Using nationally representative samples for public school teachers and principals, the authors inquired into whether principal background and school processes are related to teacher job satisfaction. Employing hierarchical linear modeling (HLM), the authors were able to control for background characteristics at both the teacher and school levels.…

Development of compact low energy election beam accelerator

International Nuclear Information System (INIS)

Katsura, Ichiro

1996-01-01

Sumitomo Heavy Industries has developed new compact accelerator jointly with its affiliated company RPC industries and some of which have already been in use in industries. Named WIPL, or WIP, which stands for Wire Ion Plasma, this accelerator is almost half the size of existing accelerators yet with performance as high as well enough to cope with industrial requirements. Background of our determination to develop such accelerator was that there prevails fairly good numbers of small laboratory units but only small numbers of production machines are in use. The main reason which brought such environment was that those production units were husky and costly. To overcome such problem and to turn situation in favor we launched the development programme and eventually succeeded to complete WIPL. Unique feature of WIPL was materialized by adopting special method of generating electrons. Unlike existing accelerators which use heated filaments WIPL utilizes the system using electron emission by bombardment of cathode plate by helium ions as electron source. Electrons are to be generated in following manner. 1) Thin helium gas is introduced in plasma chamber in which wire(s) for applying electric power. When power is supplied helium gas is turned into helium plasma by electric field. 2) Being energized by separate high voltage power source cathode plate is charged minus simultaneously. 3) Plus charged helium ions in plasma are then accelerated toward cathode plate and hit the surface. 4) Cathode plate emits electrons by bombardment and emitted electrons are compelled by the field and accelerated to the direction which helium ion came. Since such system no longer requires insulated transformers and control system for controlling electron beam current used in filament type machines equipment becomes remarkably small and economical. We really hope that this machine is accepted widely and contributes for exploiting the new horizon of electron beam market. (author)

Pushing the accelerator - speeding up drug research with accelerator mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Garner, R.C. E-mail: colin.garner@cbams.co.uk; Leong, D

2000-10-01

Accelerator mass spectrometry (AMS) is the most sensitive analytical method yet developed for elemental isotope analysis and has a broad range of applications. The measurement of {sup 14}C is of most interest to biomedical researchers but few studies have been reported using AMS in drug discovery and development. For biomedical use, {sup 14}C is incorporated into organic molecules by either radiosynthesis or biosynthetically and the isotope is used as a surrogate for the distribution of the radiolabelled molecule either in animal or human studies. The majority of users of {sup 14}C quantitate the radioactivity using decay counting usually with a liquid scintillation counter (LSC). Our Centre over the past 12 months has been evaluating and validating the use of AMS as an alternative detection method. In vitro spiking studies of human plasma with {sup 14}C-Fluconazole, a prescription antifungal drug has demonstrated an excellent correlation between AMS and LSC (correlation coefficient 0.999). Human Phase I clinical studies have been conducted with radioactive doses ranging from 120 Bq (7000 dpm) to 11 kBq (300 nCi) to provide mass balance, plasma concentration and radioactive metabolite profiling data. Limits of detection of 0.00022 Bq {sup 14}C-labelled drug/ml plasma have been accurately quantitated in a plasma background of 0.0078 Bq/ml (0.013 dpm/ml in a plasma background of 0.47 dpm/ml or 2.72 pMC in a background of 90.19 pMC)

Heavy ion acceleration at the AGS

International Nuclear Information System (INIS)

Lee, Y.Y.

1989-01-01

The Brookhaven AGS is alternating gradient synchrotron, 807 meters in circumference, which was originally designed for only protons. Using the 15 MV Brookhaven Tandem Van de Graaff as an injector, the AGS started to accelerate heavy ions of mass lighter than sulfur. Because of the relatively poor vacuum (∼10 -8 Torr), the AGS is not able to accelerate heavier ions which could not be fully stripped of electrons at the Tandem energy. When the AGS Booster, which is under construction, is completed the operation will be extended to all species of heavy ions including gold and uranium. Because ultra-high vacuum (∼10 -11 Torr) is planned, the Booster can accelerate partially stripped elements. The operational experience, the parameters, and scheme of heavy ion acceleration will be presented in detail from injection to extraction, as well as future injection into the new Relativistic Heavy Ion Collider (RHIC). A future plan to improve intensity of the accelerator will also be presented. 5 figs., 4 tabs

Digital linear accelerator: The advantages for radiotherapy

International Nuclear Information System (INIS)

Andric, S.; Maksimovic, M.; Dekic, M.; Clark, T.

1998-01-01

Technical performances of Digital Linear Accelerator were presented to point out its advantages for clinical radiotherapy treatment. The accelerator installation is earned out at Military Medical Academy, Radiotherapy Department, by Medes and Elekta companies. The unit offers many technical advantages with possibility of introduction new conformal treatment techniques as stereotactic radiosurgery, total body and total skin irradiation. In the paper are underlined advantages in relation to running conventional accelerator units at Yugoslav radiotherapy departments, both from technical and medical point of view. (author)

Particle acceleration by pulsars

International Nuclear Information System (INIS)

Arons, Jonathan.

1980-06-01

The evidence that pulsars accelerate relativistic particles is reviewed, with emphasis on the γ-ray observations. The current state of knowledge of acceleration in strong waves is summarized, with emphasis on the inability of consistent theories to accelerate very high energy particles without converting too much energy into high energy photons. The state of viable models for pair creation by pulsars is summarized, with the conclusion that pulsars very likely lose rotational energy in winds instead of in superluminous strong waves. The relation of the pair creation models to γ-ray observations and to soft X-ray observations of pulsars is outlined, with the conclusion that energetically viable models may exist, but none have yet yielded useful agreement with the extant data. Some paths for overcoming present problems are discussed. The relation of the favored models to cosmic rays is discussed. It is pointed out that the pairs made by the models may have observable consequences for observation of positrons in the local cosmic ray flux and for observations of the 511 keV line from the interstellar medium. Another new point is that asymmetry of plasma supply from at least one of the models may qualitatively explain the gross asymmetry of the X-ray emission from the Crab nebula. It is also argued that acceleration of cosmic ray nuclei by pulsars, while energetically possible, can occur only at the boundary of the bubbles blown by the pulsars, if the cosmic ray composition is to be anything like that of the known source spectrum

Radiocarbon dating with the Chalk River MP Tandem accelerator

International Nuclear Information System (INIS)

Ball, G.C.; Andrews, H.R.; Brown, R.M.; Burn, N.; Davies, W.G.; Imahori, Y.; Milton, J.C.D.

1981-01-01

During the past three years an automated radiocarbon dating system based on the MP Tandem accelerator has been developed for the analysis of 14 C in groundwater samples from the nuclear waste disposal research program and other small samples of scientific interest. At the present time 14 C/ 12 C ratio measurements can be determined with an accuracy of about 5% and the system background levels (approx. 35000 to 45000 years) are totally determined by sample and/or ion source contamination. Our goal has been to develop a dedicated reliable system for routine analysis that will produce accurate results with a minimum expenditure of human resources and accelerator beam time. Improvements required to operate the tandem accelerator as a quantitative tool have also benefited the rest of the experimental nuclear physics program. The early evolution of the dating facility was described previously. This paper is a brief report of the current status at Chalk River

2014 CERN Accelerator Schools: Plasma Wake Acceleration

CERN Multimedia

2014-01-01

A specialised school on Plasma Wake Acceleration will be held at CERN, Switzerland from 23-29 November, 2014.   This course will be of interest to staff and students in accelerator laboratories, university departments and companies working in or having an interest in the field of new acceleration techniques. Following introductory lectures on plasma and laser physics, the course will cover the different components of a plasma wake accelerator and plasma beam systems. An overview of the experimental studies, diagnostic tools and state of the art wake acceleration facilities, both present and planned, will complement the theoretical part. Topical seminars and a visit of CERN will complete the programme. Further information can be found at: http://cas.web.cern.ch/cas/PlasmaWake2014/CERN-advert.html http://indico.cern.ch/event/285444/

Radiation levels at the boundaries of the Frascati center and natural background

International Nuclear Information System (INIS)

Lucci, F.; Pelliccioni, M.

1975-01-01

The results of dosimetric controls carried out with thermoluminescent dosimeters along the boundaries of the Frascati Center since 1969 are presented. The average yearly exposure observed during the period 1969-1974 is 206mR/y, while no significant tendency is evident. In particular neither effects of accelerator shutdowns nor seasonal ones are noticed. The measurements at the boundary are also compared with measurements of natural background carried out near Frascati and in Rome, Thus we can estimate that the machine contribution to the total dose along the boundaries is equal to a small fraction of either the natural background or the general population dose limit [fr

Weakly supervised semantic segmentation using fore-background priors

Science.gov (United States)

Han, Zheng; Xiao, Zhitao; Yu, Mingjun

2017-07-01

Weakly-supervised semantic segmentation is a challenge in the field of computer vision. Most previous works utilize the labels of the whole training set and thereby need the construction of a relationship graph about image labels, thus result in expensive computation. In this study, we tackle this problem from a different perspective. We proposed a novel semantic segmentation algorithm based on background priors, which avoids the construction of a huge graph in whole training dataset. Specifically, a random forest classifier is obtained using weakly supervised training data .Then semantic texton forest (STF) feature is extracted from image superpixels. Finally, a CRF based optimization algorithm is proposed. The unary potential of CRF derived from the outputting probability of random forest classifier and the robust saliency map as background prior. Experiments on the MSRC21 dataset show that the new algorithm outperforms some previous influential weakly-supervised segmentation algorithms. Furthermore, the use of efficient decision forests classifier and parallel computing of saliency map significantly accelerates the implementation.

Virtual Accelerator for Accelerator Optics Improvement

CERN Document Server

Yan Yi Ton; Decker, Franz Josef; Ecklund, Stanley; Irwin, John; Seeman, John; Sullivan, Michael K; Turner, J L; Wienands, Ulrich

2005-01-01

Through determination of all quadrupole strengths and sextupole feed-downs by fitting quantities derivable from precision orbit measurement, one can establish a virtual accelerator that matches the real accelerator optics. These quantities (the phase advances, the Green's functions, and the coupling eigen-plane ellipses tilt angles and axis ratios) are obtained by analyzing turn-by-turn Beam Position Monitor (BPM) data with a model-independent analysis (MIA). Instead of trying to identify magnet errors, a limited number of quadrupoles are chosen for optimized strength adjustment to improve the virtual accelerator optics and then applied to the real accelerator accordingly. These processes have been successfully applied to PEP-II rings for beta beating fixes, phase and working tune adjustments, and linear coupling reduction to improve PEP-II luminosity.

Correlation analysis of measurement result between accelerator mass spectrometry and gamma counter

International Nuclear Information System (INIS)

Minamimoto, Ryogo; Cheng, C.; Oka, Takashi; Inoue, Tomio; Hamabe, Yoshimi; Shimoda, Marika

2010-01-01

The guidelines for microdosing in clinical trials were published in Japan in 2008 following the guidelines of the European Medicines Agency and the Food and Drug Administration. They recommend utilizing accelerator mass spectrometry (AMS) and positron emission tomography as candidates for monitoring drug metabolites in preclinical studies. We correlate the two methods by measuring appropriately labeled tissue samples from various mouse organs using both AMS and gamma counter. First, we measured the 14 C background levels in mouse organs using the AMS system. We then clarified the relationship between AMS and gamma counter by simultaneously administering 14 C-2-fluoro-2-deoxyglucose ( 14 C-FDG) and 18 F-2-fluoro-2-deoxyglucose ( 18 F-FDG). Tissue distribution was examined after 30 min, 1 h, 2 h and 4 h using the AMS system for 14 C-FDG and gamma counter for 18 F-FDG. Background 14 C levels were subtracted from the data obtained with radiotracer administration. The background 14 C concentration differed with tissue type measured. Background 14 C concentration in mouse liver was higher than in other organs, and was approximately 1.5-fold that in blood. The correlation coefficient (r) of the measurements between AMS ( 14 C-FDG) and gamma counter ( 18 F-FDG) was high in both normal (0.99 in blood, 0.91 in brain, 0.61 in liver and 0.78 in kidney) and tumor-bearing mice (0.95 in blood and 0.99 in tumor). The clearance profile of 18 F-FDG was nearly identical to that of 14 C-FDG measured with AMS. Accelerator mass spectrometry analysis has an excellent correlation with biodistribution measurements using gamma counter. Our results suggest that the combination of AMS and positron emission tomography (PET) can act as a complementary approach to accelerate drug development. (author)

GPU-Accelerated Real-Time Surveillance De-Weathering

OpenAIRE

Pettersson, Niklas

2013-01-01

A fully automatic de-weathering system to increase the visibility/stability in surveillance applications during bad weather has been developed. Rain, snow and haze during daylight are handled in real-time performance with acceleration from CUDA implemented algorithms. Video from fixed cameras is processed on a PC with no need of special hardware except an NVidia GPU. The system does not use any background model and does not require any precalibration. Increase in contrast is obtained in all h...

Accelerated telomere attrition is associated with relative household income, diet and inflammation in the pSoBid cohort.

Directory of Open Access Journals (Sweden)

Paul G Shiels

Full Text Available It has previously been hypothesized that lower socio-economic status can accelerate biological ageing, and predispose to early onset of disease. This study investigated the association of socio-economic and lifestyle factors, as well as traditional and novel risk factors, with biological-ageing, as measured by telomere length, in a Glasgow based cohort that included individuals with extreme socio-economic differences.A total of 382 blood samples from the pSoBid study were available for telomere analysis. For each participant, data was available for socio-economic status factors, biochemical parameters and dietary intake. Statistical analyses were undertaken to investigate the association between telomere lengths and these aforementioned parameters.The rate of age-related telomere attrition was significantly associated with low relative income, housing tenure and poor diet. Notably, telomere length was positively associated with LDL and total cholesterol levels, but inversely correlated to circulating IL-6.These data suggest lower socio-economic status and poor diet are relevant to accelerated biological ageing. They also suggest potential associations between elevated circulating IL-6, a measure known to predict cardiovascular disease and diabetes with biological ageing. These observations require further study to tease out potential mechanistic links.

Use of accelerator based neutron sources

International Nuclear Information System (INIS)

2000-05-01

With the objective of discussing new requirements related to the use of accelerator based neutron generators an Advisory Group meeting was held in October 1998 in Vienna. This meeting was devoted to the specific field of the utilization of accelerator based neutron generators. This TECDOC reports on the technical discussions and presentations that took place at this meeting and reflects the current status of neutron generators. The 14 MeV neutron generators manufactured originally for neutron activation analysis are utilised also for nuclear structure and reaction studies, nuclear data acquisition, radiation effects and damage studies, fusion related studies, neutron radiography

Acceleration and propagation of cosmic radiation. Production, oscillation and detection of neutrinos

International Nuclear Information System (INIS)

Lagage, P.-O.

1987-06-01

In recent years, the old problem of cosmic-ray acceleration and propagation has become alive again, with the discovery of the diffusive shock acceleration mechanism, and with the first measurements of the cosmic-ray antiproton flux, which appears to be higher than expected. I have shown that the new acceleration mechanism was slow and I have calculated the maximum energy that can be reached by particles accelerated in various astrophysical sites. I have also studied in detail a cosmic-ray propagation model which takes into account the antiproton measurements. Neutrino astronomy is a field much more recent and in rapid expansion, thanks to a convergence of interests between astrophysicists and elementary particle physicists. Several large neutrino detectors already exist; really huge ones are in project. I have studied the possible impact of the high energy (> 1 TeV) neutrino astronomy on models of cosmic-ray sources such as Cygnus X3. Comparing the low energy (∼ 10 MeV) cosmic-ray antineutrinos with other sources of neutrinos and antineutrinos (sun, supernova, earth...), I have pointed out that the antineutrino background resulting from all the nuclear power-stations of the planet was sizeable. This background is a nuisance for some astrophysical applications but could be useful for studies on vacuum or matter neutrino oscillations (MSW effect). I have also examined the MSW effect in another context: the travel through the earth of neutrinos from the supernova explosion SN1987a [fr

rf coaxial couplers for high-intensity linear accelerators

International Nuclear Information System (INIS)

Manca, J.J.; Knapp, E.A.

1980-02-01

Two rf coaxial couplers that are particularly suitable for intertank connection of the disk-and-washer accelerating structure for use in high-intensity linear accelerators have been developed. These devices have very high coupling to the accelerating structure and very low rf power loss at the operating frequency, and they can be designed for any relative particle velocity β > 0.4. Focusing and monitoring devices can be located inside these couplers

The acceleration of particles at propagating interplanetary shocks

Science.gov (United States)

Prinsloo, P. L.; Strauss, R. D. T.

2017-12-01

Enhancements of charged energetic particles are often observed at Earth following the eruption of coronal mass ejections (CMEs) on the Sun. These enhancements are thought to arise from the acceleration of those particles at interplanetary shocks forming ahead of CMEs, propagating into the heliosphere. In this study, we model the acceleration of these energetic particles by solving a set of stochastic differential equations formulated to describe their transport and including the effects of diffusive shock acceleration. The study focuses on how acceleration at halo-CME-driven shocks alter the energy spectra of non-thermal particles, while illustrating how this acceleration process depends on various shock and transport parameters. We finally attempt to establish the relative contributions of different seed populations of energetic particles in the inner heliosphere to observed intensities during selected acceleration events.

Analyzing radial acceleration with a smartphone acceleration sensor

Science.gov (United States)

Vogt, Patrik; Kuhn, Jochen

2013-03-01

This paper continues the sequence of experiments using the acceleration sensor of smartphones (for description of the function and the use of the acceleration sensor, see Ref. 1) within this column, in this case for analyzing the radial acceleration.

Back-reaction and effective acceleration in generic LTB dust models

International Nuclear Information System (INIS)

Sussman, Roberto A

2011-01-01

We provide a thorough examination of the conditions for the existence of back-reaction and an 'effective' acceleration (in the context of Buchert's averaging formalism) in regular generic spherically symmetric Lemaitre-Tolman-Bondi (LTB) dust models. By considering arbitrary spherical comoving domains,we verify rigorously the fulfillment of these conditions expressed in terms of suitable scalar variables that are evaluated at the boundary of every domain. Effective deceleration necessarily occurs in all domains in (a) the asymptotic radial range of models converging to a FLRW background (b) the asymptotic time range of non-vacuum hyperbolic models (c) LTB self-similar solutions and (d) near a simultaneous big bang. Accelerating domains are proven to exist in the following scenarios: (i) central vacuum regions(ii) central (non-vacuum) density voids (iii) the intermediate radial range of models converging to a FLRW background (iv) the asymptotic radial range of models converging to a Minkowski vacuum and (v) domains near and or intersecting a non-simultaneous big bang. All these scenarios occur in hyperbolic models with negative averaged and local spatial curvature though scenarios (iv) and (v) are also possible in low density regions of a class of elliptic models in which the local spatial curvature is negative but its average is positive. Rough numerical estimates between -0.003 and -0.5 were found for the effective deceleration parameter. While the existence of accelerating domains cannot be ruled out in models converging to an Einstein-de Sitter background and in domains undergoing gravitational collapse the conditions for this are very restrictive. The results obtained may provide important theoretical clues on the effects of back-reaction and averaging in more general non-spherical models. Communicated by L Andersson (paper)

Particle Accelerators: Activities and Developments in the CIEMAT

International Nuclear Information System (INIS)

Garcia Tabares, L.; Toral Fernandez, F.

2010-01-01

Although they have been in use for many years, particle accelerators are machines in constant evolution with a growing number of applications. They are not only used in basic science to understand the structure of matter, but they also have multiple technological, medical and analytical applications, etc. This fact led the CIEMAT to create the Accelerator Unit in late 2008, as part of the Technology department. Although the group had been carrying out accelerator-related activities for some time, the aim of creating the Unit was to develop not only accelerator components but also complete systems. This article contains a brief introduction to accelerators and also describes the current activities in our Unit. (Author) 8 refs.

Contribution of genetic background, traditional risk factors, and HIV-related factors to coronary artery disease events in HIV-positive persons

NARCIS (Netherlands)

Rotger, Margalida; Glass, Tracy R.; Junier, Thomas; Lundgren, Jens; Neaton, James D.; Poloni, Estella S.; van 't Wout, Angélique B.; Lubomirov, Rubin; Colombo, Sara; Martinez, Raquel; Rauch, Andri; Günthard, Huldrych F.; Neuhaus, Jacqueline; Wentworth, Deborah; van Manen, Danielle; Gras, Luuk A.; Schuitemaker, Hanneke; Albini, Laura; Torti, Carlo; Jacobson, Lisa P.; Li, Xiuhong; Kingsley, Lawrence A.; Carli, Federica; Guaraldi, Giovanni; Ford, Emily S.; Sereti, Irini; Hadigan, Colleen; Martinez, Esteban; Arnedo, Mireia; Egaña-Gorroño, Lander; Gatell, Jose M.; Law, Matthew; Bendall, Courtney; Petoumenos, Kathy; Rockstroh, Jürgen; Wasmuth, Jan-Christian; Kabamba, Kabeya; Delforge, Marc; de Wit, Stephane; Berger, Florian; Mauss, Stefan; de Paz Sierra, Mariana; Losso, Marcelo; Belloso, Waldo H.; Leyes, Maria; Campins, Antoni; Mondi, Annalisa; de Luca, Andrea; Bernardino, Ignacio; Barriuso-Iglesias, Mónica; Torrecilla-Rodriguez, Ana; Gonzalez-Garcia, Juan; Arribas, José R.; Fanti, Iuri; Gel, Silvia; Puig, Jordi; Negredo, Eugenia; Gutierrez, Mar; Domingo, Pere; Fischer, Julia; Fätkenheuer, Gerd; Alonso-Villaverde, Carlos; Macken, Alan; Woo, James; McGinty, Tara; Mallon, Patrick; Mangili, Alexandra; Skinner, Sally; Wanke, Christine A.; Reiss, Peter; Weber, Rainer; Bucher, Heiner C.; Fellay, Jacques; Telenti, Amalio; Tarr, Philip E.; Gras, A. Luuk; van Wout, Angelique B.; Arnedo-Valero, Mireia; Sierra, Mariana de Paz; Rodriguez, Ana Torrecilla; Garcia, Juan Gonzalez; Arribas, Jose R.; Aubert, V.; Barth, J.; Battegay, M.; Bernasconi, E.; Böni, J.; Bucher, H. C.; Burton-Jeangros, C.; Calmy, A.; Cavassini, M.; Egger, M.; Elzi, L.; Fehr, J.; Fellay, J.; Francioli, P.; Furrer, H.; Fux, C. A.; Gorgievski, M.; Günthard, H.; Haerry, D.; Hasse, B.; Hirsch, H. H.; Hirschel, B.; Hösli, I.; Kahlert, C.; Kaiser, L.; Keiser, O.; Kind, C.; Klimkait, T.; Kovari, H.; Ledergerber, B.; Martinetti, G.; Martinez de Tejada, B.; Metzner, K.; Müller, N.; Nadal, D.; Pantaleo, G.; Rauch, A.; Regenass, S.; Rickenbach, M.; Rudin, C.; Schmid, P.; Schultze, D.; Schöni-Affolter, F.; Schüpbach, J.; Speck, R.; Taffé, P.; Tarr, P.; Telenti, A.; Trkola, A.; Vernazza, P.; Weber, R.; Prins, Yerly S. J. M.; Kuijpers, T. W.; Scherpbier, H. J.; Boer, K.; van der Meer, J. T. M.; Wit, F. W. M. N.; Godfried, M. H.; van der Poll, T.; Nellen, F. J. B.; Lange, J. M. A.; Geerlings, S. E.; van Vugt, M.; Vrouenraets, S. M. E.; Pajkrt, D.; Bos, J. C.; van der Valk, M.; Schreij, G.; Lowe, S.; Oude Lashof, A.; Pronk, M. J. H.; Bravenboer, B.; van der Ende, M. E.; de Vries-Sluijs, T. E. M. S.; Schurink, C. A. M.; van der Feltz, M.; Nouwen, J. L.; Gelinck, L. B. S.; Verbon, A.; Rijnders, B. J. A.; van de Ven-de Ruiter, E. D.; Slobbe, L.; Haag, Den; Kauffmann, R. H.; Schippers, E. F.; Groeneveld, P. H. P.; Alleman, M. A.; Bouwhuis, J. W.; ten Kate, R. W.; Soetekouw, R.; Kroon, F. P.; van den Broek, P. J.; van Dissel, J. T.; Arend, S. M.; van Nieuwkoop, C.; de Boer, M. J. G.; Jolink, H.; den Hollander, J. G.; Pogany, K.; Bronsveld, W.; Kortmann, W.; van Twillert, G.; van Houte, D. P. F.; Polée, M. B.; van Vonderen, M. G. A.; ten Napel, C. H. H.; Kootstra, G. J.; Brinkman, K.; Blok, W. L.; Frissen, P. H. J.; Schouten, W. E. M.; van den Berk, G. E. L.; Juttmann, J. R.; van Kasteren, M. E. E.; Brouwer, A. E.; Mulder, J. W.; van Gorp, E. C. M.; Smit, P. M.; Weijer, S.; van Eeden, A.; Verhagen, D. W. M.; Sprenger, H. G.; Doedens, R.; Scholvinck, E. H.; van Assen, S.; Stek, C. J.; Hoepelman, I. M.; Mudrikova, T.; Schneider, M. M. E.; Jaspers, C. A. J. J.; Ellerbroek, P. M.; Peters, E. J. G.; Maarschalk-Ellerbroek, L. J.; Oosterheert, J. J.; Arends, J. E.; Wassenberg, M. W. M.; van der Hilst, J. C. H.; Richter, C.; van der Berg, J. P.; Gisolf, E. H.; Margolick, Joseph B.; Plankey, Michael; Crain, Barbara; Dobs, Adrian; Farzadegan, Homayoon; Gallant, Joel; Johnson-Hill, Lisette; Sacktor, Ned; Selnes, Ola; Shepard, James; Thio, Chloe; Phair, John P.; Wolinsky, Steven M.; Badri, Sheila; Conover, Craig; O'Gorman, Maurice; Ostrow, David; Palella, Frank; Ragin, Ann; Detels, Roger; Martínez-Maza, Otoniel; Aronow, Aaron; Bolan, Robert; Breen, Elizabeth; Butch, Anthony; Fahey, John; Jamieson, Beth; Miller, Eric N.; Oishi, John; Vinters, Harry; Visscher, Barbara R.; Wiley, Dorothy; Witt, Mallory; Yang, Otto; Young, Stephen; Zhang, Zuo Feng; Rinaldo, Charles R.; Becker, James T.; Cranston, Ross D.; Martinson, Jeremy J.; Mellors, John W.; Silvestre, Anthony J.; Stall, Ronald D.; Muñoz, Alvaro; Abraham, Alison; Althoff, Keri; Cox, Christopher; D'Souza, Gypsyamber; Gange, Stephen J.; Golub, Elizabeth; Schollenberger, Janet; Seaberg, Eric C.; Su, Sol; Huebner, Robin E.; Dominguez, Geraldina; Moroni, M.; Angarano, G.; Antinori, A.; Carosi, G.; Cauda, R.; Monforte, A. d'Arminio; Di Perri, G.; Galli, M.; Iardino, R.; Ippolito, G.; Lazzarin, A.; Perno, C. F.; Sagnelli, E.; Viale, P. L.; Von Schlosser, F.; d'Arminio Monforte, A.; Ammassari, A.; Andreoni, M.; Balotta, C.; Bonfanti, P.; Bonora, S.; Borderi, M.; Capobianchi, M. R.; Castagna, A.; Ceccherini-Silberstein, F.; Cozzi-Lepri, A.; de Luca, A.; Gargiulo, M.; Gervasoni, C.; Girardi, E.; Lichtner, M.; Lo Caputo, S.; Madeddu, G.; Maggiolo, F.; Marcotullio, S.; Monno, L.; Murri, R.; Mussini, C.; Puoti, M.; Torti, C.; Fanti, I.; Formenti, T.; Galli, Laura; Lorenzini, Patrizia; Montroni, M.; Giacometti, A.; Costantini, A.; Riva, A.; Tirelli, U.; Martellotta, F.; Ladisa, N.; Lazzari, G.; Verucchi, G.; Castelli, F.; Scalzini, A.; Minardi, C.; Bertelli, D.; Quirino, T.; Abeli, C.; Manconi, P. E.; Piano, P.; Vecchiet, J.; Falasca, K.; Carnevale, G.; Lorenzotti, S.; Sighinolfi, L.; Segala, D.; Leoncini, F.; Mazzotta, F.; Pozzi, M.; Cassola, G.; Viscoli, G.; Viscoli, A.; Piscopo, R.; Mazzarello, G.; Mastroianni, C.; Belvisi, V.; Caramma, I.; Chiodera, A.; Castelli, P.; Rizzardini, G.; Ridolfo, A. L.; Foschi, A.; Salpietro, S.; Galli, A.; Bigoloni, A.; Spagnuolo, V.; Merli, S.; Carenzi, L.; Moioli, M. C.; Cicconi, P.; Bisio, L.; Gori, A.; Lapadula, G.; Abrescia, N.; Chirianni, A.; de Marco, M.; Ferrari, C.; Borghi, R.; Baldelli, F.; Belfiori, B.; Parruti, G.; Ursini, T.; Magnani, G.; Ursitti, M. A.; Narciso, P.; Tozzi, V.; Vullo, V.; d'Avino, A.; Zaccarelli, M.; Gallo, L.; Acinapura, R.; Capozzi, M.; Libertone, R.; Trotta, M. P.; Tebano, G.; Cattelan, A. M.; Mura, M. S.; Caramello, P.; Orofino, G. C.; Sciandra, M.; Raise, N. N.; Ebo, F.; Pellizzer, G.; Manfrin, V.; Law, M.; Petoumenos, K.; McManus, H.; Wright, S.; Bendall, C.; Moore, R.; Edwards, S.

2013-01-01

Persons infected with human immunodeficiency virus (HIV) have increased rates of coronary artery disease (CAD). The relative contribution of genetic background, HIV-related factors, antiretroviral medications, and traditional risk factors to CAD has not been fully evaluated in the setting of HIV

Special radiation protection aspects of medical accelerators

CERN Document Server

Silari, Marco

2001-01-01

Radiation protection aspects relevant to medical accelerators are discussed. An overview is first given of general safety requirements. Next. shielding and labyrinth design are discussed in some detail for the various types of accelerators, devoting more attention to hadron machines as they are far less conventional than electron linear accelerators. Some specific aspects related to patient protection are also addressed. Finally, induced radioactivity in accelerator components and shielding walls is briefly discussed. Three classes of machines are considered: (1) medical electron linacs for 'conventional' radiation therapy. (2) low energy cyclotrons for production of radionuclides mainly for medical diagnostics and (3) medium energy cyclotrons and synchrotrons for advanced radiation therapy with protons or light ion beams (hadron therapy). (51 refs).

Drift tube suspension for high intensity linear accelerators

International Nuclear Information System (INIS)

Clark, D.C.; Frank, J.A.; Liska, D.J.; Potter, R.C.; Schamaun, R.G.

1982-01-01

The disclosure relates to a drift tube suspension for high intensity linear accelerators. The system comprises a series of box-sections girders independently adjustably mounted on a linear accelerator. A plurality of drift tube holding stems are individually adjustably mounted on each girder

Drift tube suspension for high intensity linear accelerators

Science.gov (United States)

Liska, Donald J.; Schamaun, Roger G.; Clark, Donald C.; Potter, R. Christopher; Frank, Joseph A.

1982-01-01

The disclosure relates to a drift tube suspension for high intensity linear accelerators. The system comprises a series of box-sections girders independently adjustably mounted on a linear accelerator. A plurality of drift tube holding stems are individually adjustably mounted on each girder.

Heavy Ion Fusion Accelerator Research (HIFAR)

International Nuclear Information System (INIS)

1991-04-01

This report discusses the following topics: emittance variations in current-amplifying ion induction lina; transverse emittance studies of an induction accelerator of heavy ions; drift compression experiments on MBE-4 and related emittance; low emittance uniform- density C s + sources for heavy ion fusion accelerator studies; survey of alignment of MBE-4; time-of-flight dependence on the MBE-4 quadrupole voltage; high order calculation of the multiple content of three dimensional electrostatic geometries; an induction linac injector for scaled experiments; induction accelerator test module for HIF; longitudinal instability in HIF beams; and analysis of resonant longitudinal instability in a heavy ion induction linac

Experiences with nutrition-related information during antenatal care of pregnant women of different ethnic backgrounds residing in the area of Oslo, Norway.

Science.gov (United States)

Garnweidner, Lisa M; Sverre Pettersen, Kjell; Mosdøl, Annhild

2013-12-01

to explore experiences with nutrition-related information during routine antenatal care among women of different ethnical backgrounds. individual interviews with seventeen participants were conducted twice during pregnancy. Data collection and analysis were inspired by an interpretative phenomenological approach. participants were purposively recruited at eight Mother and Child Health Centres in the area of Oslo, Norway, where they received antenatal care. participants had either immigrant backgrounds from African and Asian countries (n=12) or were ethnic Norwegian (n=5). Participants were pregnant with their first child and had a pre-pregnancy Body Mass Index above 25 kg/m(2). participants experienced that they were provided with little nutrition-related information in antenatal care. The information was perceived as presented in very general terms and focused on food safety. Weight management and the long-term prevention of diet-related chronic diseases had hardly been discussed. Participants with immigrant backgrounds appeared to be confused about information given by the midwife which was incongruent with their original food culture. The participants were actively seeking for nutrition-related information and had to navigate between various sources of information. the midwife is considered a trustworthy source of nutrition-related information. Therefore, antenatal care may have considerable potential to promote a healthy diet to pregnant women. Findings suggest that nutrition communication in antenatal care should be more tailored towards women's dietary habits and cultural background, nutritional knowledge as well as level of nutrition literacy. Copyright © 2012 Elsevier Ltd. All rights reserved.

Accelerator driven systems for energy production and waste incineration: Physics, design and related nuclear data

International Nuclear Information System (INIS)

Herman, M.; Stanculescu, A.; Paver, N.

2003-01-01

This volume contains the notes of lectures given at the workshops 'Hybrid Nuclear Systems for Energy Production, Utilisation of Actinides and Transmutation of Long-lived Radioactive Waste' and 'Nuclear Data for Science and Technology: Accelerator Driven Waste Incineration', held at the Abdus Salam ICTP in September 2001. The subject of the first workshop was focused on the so-called Accelerator Driven Systems, and covered the most important physics and technological aspects of this innovative field. The second workshop was devoted to an exhaustive survey on the acquisition, evaluation, retrieval and validation of the nuclear data relevant to the design of Accelerator Driven Systems

Accelerator driven systems for energy production and waste incineration: Physics, design and related nuclear data

Energy Technology Data Exchange (ETDEWEB)

Herman, M; Stanculescu, A [International Atomic Energy Agency, Vienna (Austria); Paver, N [University of Trieste and INFN, Trieste (Italy)

2003-06-15

This volume contains the notes of lectures given at the workshops 'Hybrid Nuclear Systems for Energy Production, Utilisation of Actinides and Transmutation of Long-lived Radioactive Waste' and 'Nuclear Data for Science and Technology: Accelerator Driven Waste Incineration', held at the Abdus Salam ICTP in September 2001. The subject of the first workshop was focused on the so-called Accelerator Driven Systems, and covered the most important physics and technological aspects of this innovative field. The second workshop was devoted to an exhaustive survey on the acquisition, evaluation, retrieval and validation of the nuclear data relevant to the design of Accelerator Driven Systems.

Community Petascale Project for Accelerator Science and Simulation: Advancing Computational Science for Future Accelerators and Accelerator Technologies

Energy Technology Data Exchange (ETDEWEB)

Spentzouris, P.; /Fermilab; Cary, J.; /Tech-X, Boulder; McInnes, L.C.; /Argonne; Mori, W.; /UCLA; Ng, C.; /SLAC; Ng, E.; Ryne, R.; /LBL, Berkeley

2011-11-14

The design and performance optimization of particle accelerators are essential for the success of the DOE scientific program in the next decade. Particle accelerators are very complex systems whose accurate description involves a large number of degrees of freedom and requires the inclusion of many physics processes. Building on the success of the SciDAC-1 Accelerator Science and Technology project, the SciDAC-2 Community Petascale Project for Accelerator Science and Simulation (ComPASS) is developing a comprehensive set of interoperable components for beam dynamics, electromagnetics, electron cooling, and laser/plasma acceleration modelling. ComPASS is providing accelerator scientists the tools required to enable the necessary accelerator simulation paradigm shift from high-fidelity single physics process modeling (covered under SciDAC1) to high-fidelity multiphysics modeling. Our computational frameworks have been used to model the behavior of a large number of accelerators and accelerator R&D experiments, assisting both their design and performance optimization. As parallel computational applications, the ComPASS codes have been shown to make effective use of thousands of processors. ComPASS is in the first year of executing its plan to develop the next-generation HPC accelerator modeling tools. ComPASS aims to develop an integrated simulation environment that will utilize existing and new accelerator physics modules with petascale capabilities, by employing modern computing and solver technologies. The ComPASS vision is to deliver to accelerator scientists a virtual accelerator and virtual prototyping modeling environment, with the necessary multiphysics, multiscale capabilities. The plan for this development includes delivering accelerator modeling applications appropriate for each stage of the ComPASS software evolution. Such applications are already being used to address challenging problems in accelerator design and optimization. The ComPASS organization

Accelerator Service

International Nuclear Information System (INIS)

Champelovier, Y.; Ferrari, M.; Gardon, A.; Hadinger, G.; Martin, J.; Plantier, A.

1998-01-01

Since the cessation of the operation of hydrogen cluster accelerator in July 1996, four electrostatic accelerators were in operation and used by the peri-nuclear teams working in multidisciplinary collaborations. These are the 4 MV Van de Graaff accelerator, 2,5 MV Van de Graaff accelerator, 400 kV ion implanter as well as the 120 kV isotope separator

Advanced Accelerator Development Strategy Report: DOE Advanced Accelerator Concepts Research Roadmap Workshop

Energy Technology Data Exchange (ETDEWEB)

None, None

2016-02-03

Over a full two day period, February 2–3, 2016, the Office of High Energy Physics convened a workshop in Gaithersburg, MD to seek community input on development of an Advanced Accelerator Concepts (AAC) research roadmap. The workshop was in response to a recommendation by the HEPAP Accelerator R&D Subpanel [1] [2] to “convene the university and laboratory proponents of advanced acceleration concepts to develop R&D roadmaps with a series of milestones and common down selection criteria towards the goal for constructing a multi-TeV e+e– collider” (the charge to the workshop can be found in Appendix A). During the workshop, proponents of laser-driven plasma wakefield acceleration (LWFA), particle-beam-driven plasma wakefield acceleration (PWFA), and dielectric wakefield acceleration (DWFA), along with a limited number of invited university and laboratory experts, presented and critically discussed individual concept roadmaps. The roadmap workshop was preceded by several preparatory workshops. The first day of the workshop featured presentation of three initial individual roadmaps with ample time for discussion. The individual roadmaps covered a time period extending until roughly 2040, with the end date assumed to be roughly appropriate for initial operation of a multi-TeV e+e– collider. The second day of the workshop comprised talks on synergies between the roadmaps and with global efforts, potential early applications, diagnostics needs, simulation needs, and beam issues and challenges related to a collider. During the last half of the day the roadmaps were revisited but with emphasis on the next five to ten years (as specifically requested in the charge) and on common challenges. The workshop concluded with critical and unanimous endorsement of the individual roadmaps and an extended discussion on the characteristics of the common challenges. (For the agenda and list of participants see Appendix B.)

IFMIF accelerators design

International Nuclear Information System (INIS)

Mosnier, A.; Ratzinger, U.

2008-01-01

The IFMIF requirement for 250 mA current of deuteron beams at a nominal energy of 40 MeV is met by means of two identical continuous wave (CW) 175 MHz linear accelerators running in parallel, each delivering a 125 mA, 40 MeV deuteron beam to the common target. This approach allows to stay within the current capability of present RF linac technology while providing operational redundancy in case of failure of one of the linacs. Each linac comprises a sequence of acceleration and beam transport/matching stages. The ion source generates a 140 mA deuteron beam at 100 keV. A low energy beam transport (LEBT) transfers the deuteron beam from the source to a radio frequency quadrupole (RFQ) cavity. The RFQ bunches and accelerates the 125 mA beam to 5 MeV. The RFQ output beam is injected through a matching section into a drift-tube-linac (DTL) where it is accelerated to the final energy of 40 MeV. In the reference design, the final acceleration stage is a conventional Alvarez-type DTL with post-couplers operating at room temperature. Operation of both the RFQ and the DTL at the same relatively low frequency is essential for accelerating the high current deuteron beam with low beam loss. The primary concern of the IFMIF linacs is the minimization of beam losses, which could limit their availability and maintainability due to excessive activation of the linac and irradiation of the environment. A careful beam dynamics design is therefore needed from the source to the target to avoid the formation of particle halo that could finally be lost in the linac or transfer lines. A superconducting solution for the high energy portion of the linac using, for example, CH-structure or coaxial-type resonators, could offer some advantages, in particular the reduction of operational costs. Careful beam dynamics simulations and comparison tests with beam during the EVEDA phase are however necessary in order to fully assess the technical feasibility of such alternative solutions

CERN: Accelerator school

International Nuclear Information System (INIS)

Anon.

1993-01-01

Full text: Jyvaskyla, a university town in central Finland, was the setting for last year's General Accelerator School organized by the CERN Accelerator School. Well over a hundred students - more than for some time - followed two weeks of lectures on a broad spectrum of accelerator topics, the first step en route to becoming the designers, builders and operators of the surprisingly large number of, accelerators of all kinds either built or planned throughout Europe and further afield. This was the fifth such school organized by CAS in a biennial cycle which alternates this introductory level with more advanced tuition. The next, advanced, school will be from 20 October - 1 November, hosted by Athens University on the Greek Island of Rhodes. (Application details will become available in Spring but would-be participants should already reserve the dates.) After Finland, the CAS caravan moved to Benalmadena near Malaga in Spain where, together with Seville University, they organized one of the joint US-CERN schools held every two years and focusing on frontier accelerator topics. This time the subject was electron-positron factories - machines for high luminosity experiments in phi, tau-charm, beauty and Z physics. Experts from both sides of the Atlantic and from Japan shared their knowledge with an equally representative audience and probed the many intensity related phenomena which must be mastered to reach design performance. A number of these topics will receive extended coverage in the next specialist CAS School which is a repeat - by public demand - of the highly successful radiofrequency course held in Oxford in 1991. This school will be in Capri, Italy, with the support of the University of Naples from 29 April to 5 May. Details and application forms are now available by e-mail (CASRF@CERNVM.CERN.CH), by fax (+41 22 7824836) or from Suzanne von Wartburg, CERN Accelerator School, 1211 Geneva 23, Switzerland

Obtaining the intrinsic electron spectrum of linear accelerators using the relation between the current of the bending magnet and the absorbed dose in water

International Nuclear Information System (INIS)

Vega, Jose M. de la; Guirado, Damian; Vilches, Manuel; Perdices, Jose I.; Lallena, Antonio M.

2008-01-01

Purpose. To present a novel methodology to model the intrinsic electron spectra of a linear accelerator and its situation with respect to the energy window. Methods. The spectra are obtained by fitting the variation of R 50 and the maximum dose rate measured in a water phantom with the bending magnet current. The obtained spectra are verified with a realistic Monte Carlo simulation of the accelerator. Results. The intrinsic spectra and their relative position with respect to the energy window of the bending magnet have been obtained for a Siemens Mevatron KDS and an ELEKTA SL20 accelerators. Conclusions. Using this method in the commissioning and scheduled revisions of the accelerator, the tuning of the current of the bending magnet could be done in such a way that both the quality of the beam and the dose rate would reach a better long-term stability

Quantitative accelerated degradation testing: Practical approaches

International Nuclear Information System (INIS)

Mohammadian, S. Hossein; Ait-Kadi, Daoud; Routhier, Francois

2010-01-01

The concept of accelerated testing by tracking degradation of samples over test time needs to be developed for reliability estimation. This paper aims at proposing practical approaches to conduct accelerated degradation testing on new and available used samples. For this purpose, product failure is related to a suitable physical property. Then, its failure time is defined as the expected time in which its property reaches the critical level. Degradation model of field samples returned from service due to a degrading failure mode has been estimated based on the least square method, and available gap between manufacturer criterion and user's claim (to report a failure) has also been discussed. For a product under some stresses, a general formula has been proposed by the superposition principle in order to estimate its degradation for independent and dependent failure modes. If used samples are available, and acceleration factor of the related test is unknown, partial aging method has been presented to considerably shorten the test time.

Uses of accelerators in energy R and D

International Nuclear Information System (INIS)

Saltmarsh, M.J.

1975-01-01

At many laboratories an increasing emphasis is being placed on energy-related research, often at the expense of more basic programs. The effects of this change can be clearly seen at accelerator laboratories, where tools traditionally reserved for nuclear and particle physicists are being applied in areas such as radiation damage, nuclear waste management, and materials science. The success of accelerator-based work in these fields is reflected by the increasing interest in proposals for new facilities devoted entirely to applied programs. Current proposals include various forms of intense neutron sources for fusion-related work, synchrotron x-ray sources for materials studies, and even the use of accelerators for large-scale nuclear waste disposal. (45 referencs) (U.S.)

Tau/Charm Factory Accelerator Report

OpenAIRE

M. E. BiaginiINFN, Laboratori Nazionali Frascati, Italy; R. BoniINFN, Laboratori Nazionali Frascati, Italy; M. BoscoloINFN, Laboratori Nazionali Frascati, Italy; A. ChiarucciINFN, Laboratori Nazionali Frascati, Italy; R. CiminoINFN, Laboratori Nazionali Frascati, Italy; A. ClozzaINFN, Laboratori Nazionali Frascati, Italy; A. DragoINFN, Laboratori Nazionali Frascati, Italy; S. GuiducciINFN, Laboratori Nazionali Frascati, Italy; C. LigiINFN, Laboratori Nazionali Frascati, Italy; G. MazzitelliINFN, Laboratori Nazionali Frascati, Italy; R. RicciINFN, Laboratori Nazionali Frascati, Italy; C. SanelliINFN, Laboratori Nazionali Frascati, Italy; M. SerioINFN, Laboratori Nazionali Frascati, Italy; A. StellaINFN, Laboratori Nazionali Frascati, Italy; S. TomassiniINFN, Laboratori Nazionali Frascati, Italy

2014-01-01

The present Report concerns the current status of the Italian Tau/Charm accelerator project and in particular discusses the issues related to the lattice design, to the accelerators systems and to the associated conventional facilities. The project aims at realizing a variable energy Flavor Factory between 1 and 4.6 GeV in the center of mass, and succeeds to the SuperB project from which it inherits most of the solutions proposed in this document. The work comes from a cooperation involving t...

An injection system for a linear accelerator

International Nuclear Information System (INIS)

Santos, A.C.R.

1978-03-01

An injection system for the Linear Accelerator is developed using the parameters of machines at the Centro Brasileiro de Pesquisas Fisicas and the Instituto Militar de Engenharia. The proposed system consists basically of a prebuncher and a chopper. The pre-buncher is used to improve the energy resolution and also to increase the accelerator target current. The chopper is used to remove from the beam the electrons that have no possibility of attaining the desired energy and that are usually lost in the walls and the cavity tube, thus producing undesirable background. Theoretical development of the chopper is performed in order to obtain its dimensions for future construction. The complete design the pre-buncher and its feed supply system and the experimental verication of its performance are also presented. It is intended to give the necessary information for the design and construction of the complete injection system proposed. (Author) [pt

Radiation protection of the operation of accelerator facilities. On high energy proton and electron accelerators

International Nuclear Information System (INIS)

Kondo, Kenjiro

1997-01-01

Problems in the radiation protection raised by accelerated particles with energy higher than several hundreds MeV in strong accelerator facilities were discussed in comparison with those with lower energy in middle- and small-scale facilities. The characteristics in the protection in such strong accelerator facilities are derived from the qualitative changes in the interaction between the high energy particles and materials and from quantitative one due to the beam strength. In the former which is dependent on the emitting mechanism of the radiation, neutron with broad energy spectrum and muon are important in the protection, and in the latter, levels of radiation and radioactivity which are proportional to the beam strength are important. The author described details of the interaction between high energy particles and materials: leading to the conclusion that in the electron accelerator facilities, shielding against high energy-blemsstrahlung radiation and -neutron is important and in the proton acceleration, shielding against neutron is important. The characteristics of the radiation field in the strong accelerator facilities: among neutron, ionized particles and electromagnetic wave, neutron is most important in shielding since it has small cross sections relative to other two. Considerations for neutron are necessary in the management of exposure. Multiplicity of radionuclides produced: which is a result of nuclear spallation reaction due to high energy particles, especially to proton. Radioactivation of the accelerator equipment is a serious problem. Other problems: the interlock systems, radiation protection for experimenters and maintenance of the equipment by remote systems. (K.H.). 11 refs

Community petascale project for accelerator science and simulation: Advancing computational science for future accelerators and accelerator technologies

International Nuclear Information System (INIS)

Spentzouris, P.; Cary, J.; McInnes, L.C.; Mori, W.; Ng, C.; Ng, E.; Ryne, R.

2008-01-01

The design and performance optimization of particle accelerators are essential for the success of the DOE scientific program in the next decade. Particle accelerators are very complex systems whose accurate description involves a large number of degrees of freedom and requires the inclusion of many physics processes. Building on the success of the SciDAC-1 Accelerator Science and Technology project, the SciDAC-2 Community Petascale Project for Accelerator Science and Simulation (ComPASS) is developing a comprehensive set of interoperable components for beam dynamics, electromagnetics, electron cooling, and laser/plasma acceleration modelling. ComPASS is providing accelerator scientists the tools required to enable the necessary accelerator simulation paradigm shift from high-fidelity single physics process modeling (covered under SciDAC1) to high-fidelity multiphysics modeling. Our computational frameworks have been used to model the behavior of a large number of accelerators and accelerator R and D experiments, assisting both their design and performance optimization. As parallel computational applications, the ComPASS codes have been shown to make effective use of thousands of processors.

Breakdowns and solutions in 15 UD pelletron ion accelerator facility at Inter-University Accelerator Centre, New Delhi

International Nuclear Information System (INIS)

Joshi, R.; Singh, P.; Suraj; Nishal, S.M.; Panwar, N.S.; Singh, M.P.; Kumar, R.; Prasad, J.; Sota, M.; Patel, V.P.; Sharma, R.P.; Kumar, Pankaj; Devi, K.D.; Ojha, S.; Gargari, S.; Chopra, S.; Kanjilal, D.

2013-01-01

15UD Pelletron accelerator, installed in Inter-University Accelerator Centre (IUAC), New Delhi, is a tandem ion accelerator and is performing well since its commissioning. Constant efforts have been put to keep high uptime and better performance of the accelerator for more than two decades. In recent years, the facility was improved by many modifications and up gradations. It has also gone through a few major breakdowns related to charging system and fiber optic cables. Out of two charging systems, one system failed and devices housed in tank stopped working due to the damage of fiber optic cables. The reasons for both of these breakdowns were studied thoroughly. The entire charging system and fiber optic cable network have been rebuilt and tested. The diagnostic techniques and maintenance methods for these two breakdowns will be discussed in this paper. (author)

Non-collision backgrounds in ATLAS

CERN Document Server

Gibson, S M; The ATLAS collaboration

2012-01-01

The proton-proton collision events recorded by the ATLAS experiment are on top of a background that is due to both collision debris and non-collision components. The latter comprises of three types: beam-induced backgrounds, cosmic particles and detector noise. We present studies that focus on the first two of these. We give a detailed description of beam-related and cosmic backgrounds based on the full 2011 ATLAS data set, and present their rates throughout the whole data-taking period. Studies of correlations between tertiary proton halo and muon backgrounds, as well as, residual pressure and resulting beam-gas events seen in beam-condition monitors will be presented. Results of simulations based on the LHC geometry and its parameters will be presented. They help to better understand the features of beam-induced backgrounds in each ATLAS sub-detector. The studies of beam-induced backgrounds in ATLAS reveal their characteristics and serve as a basis for designing rejection tools that can be applied in physic...

Advanced concepts for acceleration

International Nuclear Information System (INIS)

Keefe, D.

1986-07-01

Selected examples of advanced accelerator concepts are reviewed. Such plasma accelerators as plasma beat wave accelerator, plasma wake field accelerator, and plasma grating accelerator are discussed particularly as examples of concepts for accelerating relativistic electrons or positrons. Also covered are the pulsed electron-beam, pulsed laser accelerator, inverse Cherenkov accelerator, inverse free-electron laser, switched radial-line accelerators, and two-beam accelerator. Advanced concepts for ion acceleration discussed include the electron ring accelerator, excitation of waves on intense electron beams, and two-wave combinations

Accelerated EM-based clustering of large data sets

NARCIS (Netherlands)

Verbeek, J.J.; Nunnink, J.R.J.; Vlassis, N.

2006-01-01

Motivated by the poor performance (linear complexity) of the EM algorithm in clustering large data sets, and inspired by the successful accelerated versions of related algorithms like k-means, we derive an accelerated variant of the EM algorithm for Gaussian mixtures that: (1) offers speedups that

Modeling of thermalization phenomena in coaxial plasma accelerators

Science.gov (United States)

Subramaniam, Vivek; Panneerchelvam, Premkumar; Raja, Laxminarayan L.

2018-05-01

Coaxial plasma accelerators are electromagnetic acceleration devices that employ a self-induced Lorentz force to produce collimated plasma jets with velocities ~50 km s‑1. The accelerator operation is characterized by the formation of an ionization/thermalization zone near gas inlet of the device that continually processes the incoming neutral gas into a highly ionized thermal plasma. In this paper, we present a 1D non-equilibrium plasma model to resolve the plasma formation and the electron-heavy species thermalization phenomena that take place in the thermalization zone. The non-equilibrium model is based on a self-consistent multi-species continuum description of the plasma with finite-rate chemistry. The thermalization zone is modelled by tracking a 1D gas-bit as it convects down the device with an initial gas pressure of 1 atm. The thermalization process occurs in two stages. The first is a plasma production stage, associated with a rapid increase in the charged species number densities facilitated by cathode surface electron emission and volumetric production processes. The production stage results in the formation of a two-temperature plasma with electron energies of ~2.5 eV in a low temperature background gas of ~300 K. The second, a temperature equilibration stage, is characterized by the energy transfer between the electrons and heavy species. The characteristic length scale for thermalization is found to be comparable to axial length of the accelerator thus putting into question the equilibrium magnetohydrodynamics assumption used in modeling coaxial accelerators.

Accelerating tube for the ''EG-1'' electrostatic accelerator

International Nuclear Information System (INIS)

Romanov, V.A.; Ivanov, V.V.; Krupnov, E.P.; Debin, V.K.; Dudkin, N.I.; Volodin, V.I.

1980-01-01

A design of an accelerating tube (AT) for an electrostatic accelerator of the EG-1 type is described. Primary consideration in the development of the AT has been given to increasing the electric strength of accelerating gaps, the vacuum conductivity and better insulator screening from charged particles. After AT vacuum and high-voltage ageing in the accelerator, a hydrogen ions beam of up to 80 μA has been produced. The beam was adequately shaped in the energy range from 1.8 to 5.0 MeV [ru

Metabolic syndrome but not obesity measures are risk factors for accelerated age-related glomerular filtration rate decline in the general population.

Science.gov (United States)

Stefansson, Vidar T N; Schei, Jørgen; Solbu, Marit D; Jenssen, Trond G; Melsom, Toralf; Eriksen, Bjørn O

2018-05-01

Rapid age-related glomerular filtration rate (GFR) decline increases the risk of end-stage renal disease, and a low GFR increases the risk of mortality and cardiovascular disease. High body mass index and the metabolic syndrome are well-known risk factors for patients with advanced chronic kidney disease, but their role in accelerating age-related GFR decline independent of cardiovascular disease, hypertension and diabetes is not adequately understood. We studied body mass index, waist circumference, waist-hip ratio and metabolic syndrome as risk factors for accelerated GFR decline in 1261 middle-aged people representative of the general population without diabetes, cardiovascular disease or kidney disease. GFR was measured as iohexol clearance at baseline and repeated after a median of 5.6 years. Metabolic syndrome was defined as fulfilling three out of five criteria, based on waist circumference, blood pressure, glucose, high-density lipoprotein cholesterol and triglycerides. The mean GFR decline rate was 0.95 ml/min/year. Neither the body mass index, waist circumference nor waist-hip ratio predicted statistically significant changes in age-related GFR decline, but individuals with baseline metabolic syndrome had a significant mean of 0.30 ml/min/year faster decline than individuals without metabolic syndrome in a multivariable adjusted linear regression model. This association was mainly driven by the triglyceride criterion of metabolic syndrome, which was associated with a significant 0.36 ml/min/year faster decline when analyzed separately. Results differed significantly when GFR was estimated using creatinine and/or cystatin C. Thus, metabolic syndrome, but not the body mass index, waist circumference or waist-hip ratio, is an independent risk factor for accelerated age-related GFR decline in the general population. Copyright © 2017 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.

Accelerating the cosmic microwave background map-making procedure through preconditioning

Science.gov (United States)

Szydlarski, M.; Grigori, L.; Stompor, R.

2014-12-01

Estimation of the sky signal from sequences of time ordered data is one of the key steps in cosmic microwave background (CMB) data analysis, commonly referred to as the map-making problem. Some of the most popular and general methods proposed for this problem involve solving generalised least-squares (GLS) equations with non-diagonal noise weights given by a block-diagonal matrix with Toeplitz blocks. In this work, we study new map-making solvers potentially suitable for applications to the largest anticipated data sets. They are based on iterative conjugate gradient (CG) approaches enhanced with novel, parallel, two-level preconditioners. We apply the proposed solvers to examples of simulated non-polarised and polarised CMB observations and a set of idealised scanning strategies with sky coverage ranging from a nearly full sky down to small sky patches. We discuss their implementation for massively parallel computational platforms and their performance for a broad range of parameters that characterise the simulated data sets in detail. We find that our best new solver can outperform carefully optimised standard solvers used today by a factor of as much as five in terms of the convergence rate and a factor of up to four in terms of the time to solution, without significantly increasing the memory consumption and the volume of inter-processor communication. The performance of the new algorithms is also found to be more stable and robust and less dependent on specific characteristics of the analysed data set. We therefore conclude that the proposed approaches are well suited to address successfully challenges posed by new and forthcoming CMB data sets.

Electron Cloud Effects in Accelerators

International Nuclear Information System (INIS)

Furman, M A

2013-01-01

We present a brief summary of various aspects of the electron-cloud effect (ECE) in accelerators. For further details, the reader is encouraged to refer to the proceedings of many prior workshops, either dedicated to EC or with significant EC contents, including the entire 'ECLOUD' series. In addition, the proceedings of the various flavors of Particle Accelerator Conferences contain a large number of EC-related publications. The ICFA Beam Dynamics Newsletter series contains one dedicated issue, and several occasional articles, on EC. An extensive reference database is the LHC website on EC. (author)

Machine Protection: Availability for Particle Accelerators

CERN Document Server

Apollonio, Andrea; Schmidt, Ruediger

2015-03-16

Machine availability is a key indicator for the performance of the next generation of particle accelerators. Availability requirements need to be carefully considered during the design phase to achieve challenging objectives in different fields, as e.g. particle physics and material science. For existing and future High-Power facilities, such as ESS (European Spallation Source) and HL-LHC (High-Luminosity LHC), operation with unprecedented beam power requires highly dependable Machine Protection Systems (MPS) to avoid any damage-induced downtime. Due to the high complexity of accelerator systems, finding the optimal balance between equipment safety and accelerator availability is challenging. The MPS architecture, as well as the choice of electronic components, have a large influence on the achievable level of availability. In this thesis novel methods to address the availability of accelerators and their protection systems are presented. Examples of studies related to dependable MPS architectures are given i...

Proceedings of B Factories, the state of the art in accelerators, detectors and physics

International Nuclear Information System (INIS)

Hitlin, D.

1992-11-01

The conference B Factories, The State of the Art in Accelerators, Detectors and Physics was held at Stanford Linear Accelerator Center on April 6-10, 1992. The guiding principle of the conference was to bring together accelerator physicists and high energy experimentalists and theorists at the same time, with the goal of encouraging communication in defining and solving problems in a way which cut across narrow areas of specialization. Thus the conference was, in large measure, two distinct conferences, one involving accelerator specialists, the other theorists and experimentalists. There were initial and closing plenary sessions, and three separate tracks of parallel sessions, called Accelerator, Detector/Physics and Joint Interest sessions. This report contains the papers of this conference, the general topics of these cover: vacuum system, lattice design, beam-beam interactions, rf systems, feedback systems, measuring instrumentation, the interaction region, radiation background, particle detectors, particle tracking and identification, data acquisition, and computing system, and particle theory

Proceedings of B Factories, the state of the art in accelerators, detectors and physics

Energy Technology Data Exchange (ETDEWEB)

Hitlin, D. (ed.) (California Inst. of Tech., Pasadena, CA (United States))

1992-11-01

The conference B Factories, The State of the Art in Accelerators, Detectors and Physics was held at Stanford Linear Accelerator Center on April 6-10, 1992. The guiding principle of the conference was to bring together accelerator physicists and high energy experimentalists and theorists at the same time, with the goal of encouraging communication in defining and solving problems in a way which cut across narrow areas of specialization. Thus the conference was, in large measure, two distinct conferences, one involving accelerator specialists, the other theorists and experimentalists. There were initial and closing plenary sessions, and three separate tracks of parallel sessions, called Accelerator, Detector/Physics and Joint Interest sessions. This report contains the papers of this conference, the general topics of these cover: vacuum system, lattice design, beam-beam interactions, rf systems, feedback systems, measuring instrumentation, the interaction region, radiation background, particle detectors, particle tracking and identification, data acquisition, and computing system, and particle theory.

CAS CERN Accelerator School superconductivity in particle accelerators

International Nuclear Information System (INIS)

Turner, S.

1989-01-01

One of the objectives of the CERN Accelerator School is to run courses on specialised topics in the particle accelerator field. The present volume contains the proceedings of one such course, this time organized in conjunction with the Deutsches Elektronen Synchrotron (DESY) on the subject of superconductivity in particle accelerators. This course reflects the very considerable progress made over the last few years in the use of the technology for the magnet and radio-frequency systems of many large and small accelerators already in use or nearing completion, while also taking account of the development work now going on for future machines. The lectures cover the theory of superconductivity, cryogenics and accelerator magnets and cavities, while the seminars include superfluidity, superconductors, special magnets and the prospects for high-temperature superconductors. (orig.)

Could the cosmic acceleration be transient?

Energy Technology Data Exchange (ETDEWEB)

Guimaraes, Antonio C.C.; Lima, J.A.S. [Universidade de Sao Paulo (IAG/USP), SP (Brazil). Inst. de Astronomia, Geofisica e Ciencias Atmosfericas

2011-07-01

Full text: The possibility of a transient cosmic acceleration appears in several theoretical scenarios and is theoretically interesting because it solves some difficulties inherent to eternally accelerating universes (like {Lambda}CDM). On the observational side, some authors, using a dynamical Ansatz for the dark energy equation of state, have suggested that the cosmic acceleration have already peaked and that we are currently witnessing its slowing down. Here, a possible slowing down of the cosmic expansion is investigated through a cosmographic approach. By expanding the luminous distance to fourth order and fitting the SNe Ia data from the most recent compilations (Union, Constitution and Union 2), the marginal likelihood distribution for the deceleration parameter today indicates that there is a considerable probability for q{sub 0} > 0. Also in contrast to the prediction of the {Lambda}CDM model, the cosmographic q(z) reconstruction suggests that the cosmic acceleration could already have peaked and be presently slowing down, what would imply that the recent accelerated expansion of the Universe is a transient phenomenon. It is also shown that to describe a transient acceleration the luminous distance needs to be expanded at least to fourth order. The present cosmographic results depend neither on the validity of general relativity nor on the matter-energy contents of the Universe. (author)

Acceleration and propagation of cosmic rays. Production, oscillation and detection of neutrinos

International Nuclear Information System (INIS)

Lagage, P.O.

1987-01-01

This thesis is devoted to studies on cosmic rays and neutrinos, particles astrophysically relevant. In recent years, the old problem of cosmic-ray acceleration and propagation has become alive again, with the discovery of the diffusive shock acceleration mechanism, and with the first measurements of the cosmic-ray antiproton flux, which appears to be higher than expected. I have shown that the new acceleration mechanism was slow and I have calculated the maximum energy that can be reached by particles accelerated in various astrophysical sites. I have also studied in detail a cosmic-ray propagation model which takes into account the antiproton measurements. Neutrino astronomy is a field much more recent and in rapid expansion, thanks to a convergence of interests between astrophysicists and elementary particle physicists. Several large neutrino detectors already exist; really huge ones are in project. I have studied the possible impact of the high energy (> 1 TeV) neutrino astronomy on models of cosmic-ray sources such as Cygnus X3. Comparing the low energy (∼ 10 MeV) cosmic-ray antineutrinos with other sources of neutrinos and antineutrinos (sun, supernova, earth ...), I have pointed out that the antineutrino background resulting from all the nuclear power-stations of the planet was sizeable. This background is a nuisance for some astrophysical applications but could be useful for studies on vacuum or matter neutrino oscillations (MSW effect). I have also examined the MSW effect in another context: the travel through the earth of neutrinos from the supernova explosion SN1987a [fr

A statistical comparison of accelerated concrete testing methods

Directory of Open Access Journals (Sweden)

Denny Meyer

1997-01-01

Full Text Available Accelerated curing results, obtained after only 24 hours, are used to predict the 28 day strength of concrete. Various accelerated curing methods are available. Two of these methods are compared in relation to the accuracy of their predictions and the stability of the relationship between their 24 hour and 28 day concrete strength. The results suggest that Warm Water accelerated curing is preferable to Hot Water accelerated curing of concrete. In addition, some other methods for improving the accuracy of predictions of 28 day strengths are suggested. In particular the frequency at which it is necessary to recalibrate the prediction equation is considered.

Proton linear accelerators: A theoretical and historical introduction

International Nuclear Information System (INIS)

Lapostolle, P.M.

1989-07-01

From the beginning, the development of linear accelerators has followed a number of different directions. This report surveys the basic ideas and general principles of such machines, pointing out the problems that have led to the various improvements, with the hope that it may also aid further progress. After a brief historical survey, the principal aspects of accelerator theory are covered in some detail: phase stability, focusing, radio-frequency accelerating structures, the detailed calculation of particle dynamics, and space-charge effects at high intensities. These developments apply essentially to proton and ion accelerators, and only the last chapter deals with a few aspects relative to electrons. 134 refs

Study on the limiting acceleration rate in the VLEPP linear accelerator

International Nuclear Information System (INIS)

Balakin, V.E.; Brezhnev, O.N.; Zakhvatkin, M.N.

1987-01-01

To realize the design of colliding linear electron-positron beams it is necessary to solve the radical problem of production of accelerating structure with acceleration rate of approximately 100 MeV/m which can accelerate 10 12 particles in a bunch. Results of experimental studies of the limiting acceleration rate in the VLEPP accelerating structure are presented. Accelerating sections of different length were tested. When testing sections 29 cm long the acceleration rate of 55 MeV/m was attained, and for 1 m section the value reached 40 MeV/m. The maximum rate of acceleration (90 MeV/m) was attained when electric field intensity on the structure surface constituted more than 150 MV/m

Particle-accelerator decommissioning

International Nuclear Information System (INIS)

Opelka, J.H.; Mundis, R.L.; Marmer, G.J.; Peterson, J.M.; Siskind, B.; Kikta, M.J.

1979-12-01

Generic considerations involved in decommissioning particle accelerators are examined. There are presently several hundred accelerators operating in the United States that can produce material containing nonnegligible residual radioactivity. Residual radioactivity after final shutdown is generally short-lived induced activity and is localized in hot spots around the beam line. The decommissioning options addressed are mothballing, entombment, dismantlement with interim storage, and dismantlement with disposal. The recycle of components or entire accelerators following dismantlement is a definite possibility and has occurred in the past. Accelerator components can be recycled either immediately at accelerator shutdown or following a period of storage, depending on the nature of induced activation. Considerations of cost, radioactive waste, and radiological health are presented for four prototypic accelerators. Prototypes considered range from small accelerators having minimal amounts of radioactive mmaterial to a very large accelerator having massive components containing nonnegligible amounts of induced activation. Archival information on past decommissionings is presented, and recommendations concerning regulations and accelerator design that will aid in the decommissioning of an accelerator are given

Cosmological evolution of vacuum and cosmic acceleration

International Nuclear Information System (INIS)

Kaya, Ali

2010-01-01

It is known that the unregularized expressions for the stress-energy tensor components corresponding to subhorizon and superhorizon vacuum fluctuations of a massless scalar field in a Friedmann-Robertson-Walker background are characterized by the equation of state parameters ω = 1/3 and ω = -1/3, which are not sufficient to produce cosmological acceleration. However, the form of the adiabatically regularized finite stress-energy tensor turns out to be completely different. By using the fact that vacuum subhorizon modes evolve nearly adiabatically and superhorizon modes have ω = -1/3, we approximately determine the regularized stress-energy tensor, whose conservation is utilized to fix the time dependence of the vacuum energy density. We then show that vacuum energy density grows from zero up to H 4 in about one Hubble time, vacuum fluctuations give positive acceleration of the order of H 4 /M 2 p and they can completely alter the cosmic evolution of the universe dominated otherwise by the cosmological constant, radiation or pressureless dust. Although the magnitude of the acceleration is tiny to explain the observed value today, our findings indicate that the cosmological backreaction of vacuum fluctuations must be taken into account in early stages of cosmic evolution.

Study and realization of an electron linear accelerator. Dynamics of accelerated electrons; Etude et realisation d'un accelerateur lineaire d'electrons. Dynamique des electrons acceleres

Energy Technology Data Exchange (ETDEWEB)

Bernard, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1967-04-01

The theoretical characteristics of the electron linear accelerator are: 30 MeV for the energy W{sub S} and 250 mA for the peak current I{sub c}. The main utilization is the intense production of fast neutrons by the reactions ({gamma},n) and ({gamma},f) induced in a target of natural uranium by the accelerated electrons. In the first part of the thesis, relative to the study and the realization of the accelerator, a new equation of dispersion is established analytically when the guide is loaded with round-edged irises. The relation is compared with the equation established by CHU and Hansen, WALKINSHAW, KVASIL in the case of a guide loaded with flat-edged irises. The experimental and theoretical curves of dispersion are compared. The accuracy of every relation of dispersion is estimated. The second part of the thesis is relative to the theoretical study of the electrons dynamics in the guide; it allows the derivation of the parameters of the beam: dispersion of phase, energy, dispersion of energy and the relation W{sub S} = f (I{sub c}). The results relative to the first experiments are given and compared with the theoretical expectations. (author) [French] Les caracteristiques nominales theoriques de l'accelerateur lineaire d'electrons sont: 30 MeV pour l'energie W{sub S} et 250 mA pour le courant de crete I{sub c}. L'utilisation principale envisagee est la production de neutrons rapides par les reactions ({gamma},n) et ({gamma},f) induites dans une cible d'uranium naturel par les electrons acceleres. Dans la premiere partie de la these relative a l'elude et a la realisation de l'accelerateur, une nouvelle equation de dispersion (ou equation aux frequences) est etablie analytiquement pour un guide charge par des iris a bord rond. Cette relation est comparee a celles etablies par CHU et HANSEN, WALKINSHAW, KVASIL dans le cas du guide charge par des iris a bord plat. On compare les courbes de dispersion theoriques et experimentales et on evalue la precision de

Ghosts in the self-accelerating DGP branch with Gauss–Bonnet effect

Energy Technology Data Exchange (ETDEWEB)

Liu, Yen-Wei; Izumi, Keisuke; Bouhmadi-López, Mariam; Chen, Pisin

2015-06-01

The Dvali–Gabadadze–Porrati brane-world model provides a possible approach to address the late-time cosmic acceleration. However, it has subsequently been pointed out that a ghost instability will arise on the self-accelerating branch. Here, we carefully investigate whether this ghost problem could be possibly cured by introducing the Gauss–Bonnet term in the five-dimensional bulk action, a natural generalization to the Dvali–Gabadadze–Porrati model. Our analysis is carried out for a background where a de Sitter brane is embedded in an anti–de Sitter bulk. Our result shows that the ghost excitations cannot be avoided even in this modified model.

Recent status of superconductors for accelerator magnets

International Nuclear Information System (INIS)

Greene, A.F.

1992-01-01

A survey is given of superconductor wire and cable which has been or will be used for construction of dipole magnets for all of the large European and US superconducting accelerator rings. Included is a simplified view of the construction methods and operating requirements of an accelerator dipole magnet, with emphasis on required superconductor performance. The methods of fabricating Nb-Ti superconductors are described, including the critical parameters and materials requirements. The superconductor performance requirements are summarized in an effort to relate why these are important to accelerator designers. Some of the recently observed time dependent effects are covered briefly

Advanced Accelerator Test Facility (AATF) upgrade plan

International Nuclear Information System (INIS)

Gai, W.; Ho, C.; Konecny, R.

1989-01-01

We have successfully demonstrated the principles of wake-field acceleration using structures (cavity, dielectric) and plasmas as wake-field devices using the AATF at Argonne National Laboratory. Due to the limited driver electron pulse intensity and relative long pulse length, only modest accelerating gradients were observed. In order to study the wake field effects in much greater detail and demonstrate the feasibility of wake-field accelerator for high energy physics, we are considering construction of a laser photocathode injector on the existing 20 MeV Chem-Linac to produce very intense and short electron pulses. 10 refs., 5 figs

Accelerated protein digestion and amino acid absorption after Roux-en-Y gastric bypass

DEFF Research Database (Denmark)

Bojsen-Møller, Anna Kirstine; Jacobsen, Siv H; Dirksen, Carsten

2015-01-01

BACKGROUND: Roux-en-Y gastric bypass (RYGB) involves exclusion of major parts of the stomach and changes in admixture of gastro-pancreatic enzymes, which could have a major impact on protein digestion and amino acid absorption. OBJECTIVE: We investigated the effect of RYGB on amino acid appearance......: RYGB accelerates caseinate digestion and amino acid absorption, resulting in faster and higher but more transient postprandial elevation of plasma amino acids. Changes are likely mediated by accelerated intestinal nutrient entry and clearly demonstrate that protein digestion is not impaired after RYGB...

Linear Accelerator Development for Cancer Treatment at SLRI

International Nuclear Information System (INIS)

Juntong, N.

2014-01-01

Linear accelerator (linac) technology has been widely utilised for cancer treatment in hospital. This linac utilised an accelerated electron beam to create x-ray beam for radiotherapy. At Synchrotron Light Research Institute (SLRI), the idea to fabricate the prototype of medical linac with low cost for domestic use in Thailand was proposed and the budget has been granted. There are three objectives of this proposal: 1) to develop prototype of medical linac by the ability of domestic people for reducing the machine import and maintenance costs,2) to encourage researching in science and technology concerning medical application for the practical use products, and 3) to develop knowledge and expertise in accelerator and concerning technologies of medical linac. In the first phase, the electron beam energy of the prototype machine will be 6 MeV or equivalent to x-ray energy of 6 MV based on discussions with several hospitals in the country. This energy level is considered suitable for the Thais due to shapes and sizes of the bodies. A brief introduction of background, objectives, and scope of the project will be presented together with the project timeline. Progression of project activities will also be discussed.

Source-to-accelerator quadrupole matching section for a compact linear accelerator

Science.gov (United States)

Seidl, P. A.; Persaud, A.; Ghiorso, W.; Ji, Q.; Waldron, W. L.; Lal, A.; Vinayakumar, K. B.; Schenkel, T.

2018-05-01

Recently, we presented a new approach for a compact radio-frequency (RF) accelerator structure and demonstrated the functionality of the individual components: acceleration units and focusing elements. In this paper, we combine these units to form a working accelerator structure: a matching section between the ion source extraction grids and the RF-acceleration unit and electrostatic focusing quadrupoles between successive acceleration units. The matching section consists of six electrostatic quadrupoles (ESQs) fabricated using 3D-printing techniques. The matching section enables us to capture more beam current and to match the beam envelope to conditions for stable transport in an acceleration lattice. We present data from an integrated accelerator consisting of the source, matching section, and an ESQ doublet sandwiched between two RF-acceleration units.

Computational and experimental investigation of plasma deflagration jets and detonation shocks in coaxial plasma accelerators

Science.gov (United States)

Subramaniam, Vivek; Underwood, Thomas C.; Raja, Laxminarayan L.; Cappelli, Mark A.

2018-02-01

We present a magnetohydrodynamic (MHD) numerical simulation to study the physical mechanisms underlying plasma acceleration in a coaxial plasma gun. Coaxial plasma accelerators are known to exhibit two distinct modes of operation depending on the delay between gas loading and capacitor discharging. Shorter delays lead to a high velocity plasma deflagration jet and longer delays produce detonation shocks. During a single operational cycle that typically consists of two discharge events, the plasma acceleration exhibits a behavior characterized by a mode transition from deflagration to detonation. The first of the discharge events, a deflagration that occurs when the discharge expands into an initially evacuated domain, requires a modification of the standard MHD algorithm to account for rarefied regions of the simulation domain. The conventional approach of using a low background density gas to mimic the vacuum background results in the formation of an artificial shock, inconsistent with the physics of free expansion. To this end, we present a plasma-vacuum interface tracking framework with the objective of predicting a physically consistent free expansion, devoid of the spurious shock obtained with the low background density approach. The interface tracking formulation is integrated within the MHD framework to simulate the plasma deflagration and the second discharge event, a plasma detonation, formed due to its initiation in a background prefilled with gas remnant from the deflagration. The mode transition behavior obtained in the simulations is qualitatively compared to that observed in the experiments using high framing rate Schlieren videography. The deflagration mode is further investigated to understand the jet formation process and the axial velocities obtained are compared against experimentally obtained deflagration plasma front velocities. The simulations are also used to provide insight into the conditions responsible for the generation and sustenance of

Electrostatic accelerators

CERN Document Server

Hinterberger, F

2006-01-01

The principle of electrostatic accelerators is presented. We consider Cockcroft– Walton, Van de Graaff and Tandem Van de Graaff accelerators. We resume high voltage generators such as cascade generators, Van de Graaff band generators, Pelletron generators, Laddertron generators and Dynamitron generators. The speci c features of accelerating tubes, ion optics and methods of voltage stabilization are described. We discuss the characteristic beam properties and the variety of possible beams. We sketch possible applications and the progress in the development of electrostatic accelerators.

Centrifugal acceleration in the magnetotail lobes

Directory of Open Access Journals (Sweden)

H. Nilsson

2010-02-01

Full Text Available Combined Cluster EFW and EDI measurements have shown that cold ion outflow in the magnetospheric lobes dominates the hydrogen ion outflow from the Earth's atmosphere. The ions have too low kinetic energy to be measurable with particle instruments, at least for the typical spacecraft potential of a sunlit spacecraft in the tenuous lobe plasmas outside a few R_E. The measurement technique yields both density and bulk velocity, which can be combined with magnetic field measurements to estimate the centrifugal acceleration experienced by these particles. We present a quantitative estimate of the centrifugal acceleration, and the velocity change with distance which we would expect due to centrifugal acceleration. It is found that the centrifugal acceleration is on average outward with an average value of about of 5 m s⁻². This is small, but acting during long transport times and over long distances the cumulative effect is significant, while still consistent with the relatively low velocities estimated using the combination of EFW and EDI data. The centrifugal acceleration should accelerate any oxygen ions in the lobes to energies observable by particle spectrometers. The data set also put constraints on the effectiveness of any other acceleration mechanisms acting in the lobes, where the total velocity increase between 5 and 19 R_E geocentric distance is less than 5 km s⁻¹.

Pellet acceleration studies relating to the refuelling of a steady-state fusion reactor

International Nuclear Information System (INIS)

Dimock, D.; Jensen, K.; Jensen, V.O.; Joergensen, L.W.; Pecseli, H.L.; Soerensen, H.; Oester, F.

1975-11-01

Several methods for refuelling a steady state-fusion reactor have been proposed, and the pellet method seems advantageous if the pellet can be accelerated to the necessary velocity. A study group was formed to analyze this acceleration problem. Two pellet velocity values were considered: 10 4 m/s and 300 m/s. A pellet velocity of 10 4 m/s may be suitable in the case of a reactor, whereas 300 m/s is believed to be a reasonable velocity at which to perform realistic ablation experiments in the near future. A pneumatic acceleration method was found promising. The pressure is either supplied separately or by evaporation of a part of the pellet. In the latter case, a spark behind the pellet should provide the evoporation and the necessary heating of the driving gas. A preliminary test at room temperature with pellets made of beeswax (the density being ten times that of solid hydrogen, and plastic properties similar to those of solid hydrogen) resulted in a pellet velocity of 100 m/s at a modest value of the energy supplied to the spark. (Auth.)

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.

Multiperiodic accelerator structures for linear particle accelerators

International Nuclear Information System (INIS)

Tran, D.T.

1975-01-01

High efficiency linear accelerator structures, comprised of a succession of cylindrical resonant cavities for acceleration, are described. Coupling annular cavities are located at the periphery, each being coupled to two adjacent cylindrical cavities. (auth)

A hybrid dielectric and iris loaded periodic accelerating structure

International Nuclear Information System (INIS)

Zou, P.; Xiao, L.; Sun, X.; Gai, W.

2001-01-01

One disadvantage of conventional iris-loaded accelerating structures is the high ratio of the peak surface electric field to the peak axial electric field useful for accelerating a beam. Typically this ratio E s /E a ≥ 2. The high surface electric field relative to the accelerating gradient may prove to be a limitation for realizing technologies for very high gradient accelerators. In this paper, we present a scheme that uses a hybrid dielectric and iris loaded periodic structure to reduce E s /E a to near unity, while the shunt impedance per unit length r and the quality factor Q compare favorably with conventional metallic structures. The analysis based on MAFIA simulations of such structures shows that we can lower the peak surface electric field close to the accelerating gradient while maintaining high acceleration efficiency as measured by r/Q. Numerical examples of X-band hybrid accelerating structures are given

Ultra-accelerated natural sunlight exposure testing

Science.gov (United States)

Jorgensen, Gary J.; Bingham, Carl; Goggin, Rita; Lewandowski, Allan A.; Netter, Judy C.

2000-06-13

Process and apparatus for providing ultra accelerated natural sunlight exposure testing of samples under controlled weathering without introducing unrealistic failure mechanisms in exposed materials and without breaking reciprocity relationships between flux exposure levels and cumulative dose that includes multiple concurrent levels of temperature and relative humidity at high levels of natural sunlight comprising: a) concentrating solar flux uniformly; b) directing the controlled uniform sunlight onto sample materials in a chamber enclosing multiple concurrent levels of temperature and relative humidity to allow the sample materials to be subjected to accelerated irradiance exposure factors for a sufficient period of time in days to provide a corresponding time of about at least a years worth of representative weathering of the sample materials.

Background enhancement in breast MR: Correlation with breast density in mammography and background echotexture in ultrasound

International Nuclear Information System (INIS)

Ko, Eun Sook; Lee, Byung Hee; Choi, Hye Young; Kim, Rock Bum; Noh, Woo-Chul

2011-01-01

Objective: This study aimed to determine whether background enhancement on MR was related to mammographic breast density or ultrasonographic background echotexture in premenopausal and postmenopausal women. Materials and methods: We studied 142 patients (79 premenopausal, 63 postmenopausal) who underwent mammography, ultrasonography, and breast MR. We reviewed the mammography for overall breast density of the contralateral normal breast according to the four-point scale of the BI-RADS classification. Ultrasound findings were classified as homogeneous or heterogeneous background echotexture according to the BI-RADS lexicon. We rated background enhancement on a contralateral breast MR into four categories based on subtraction images: absent, mild, moderate, and marked. All imaging findings were interpreted independently by two readers without knowledge of menstrual status, imaging findings of other modalities. Results: There were significant differences between the premenopausal and postmenopausal group in distribution of mammographic breast density, ultrasonographic background echotexture, and degree of background enhancement. Regarding the relationship between mammographic density and background enhancement, there was no significant correlation. There was significant relationship between ultrasonographic background echotexture and background enhancement in both premenopausal and postmenopausal groups. Conclusion: There is a significant correlation between ultrasonographic background echotexture and background enhancement in MR regardless of menopausal status. Interpreting breast MR, or scheduling for breast MR of women showing heterogeneous background echotexture needs more caution.

The Accelerated Late Adsorption of Pulmonary Surfactant

Science.gov (United States)

2011-01-01

Adsorption of pulmonary surfactant to an air−water interface lowers surface tension (γ) at rates that initially decrease progressively, but which then accelerate close to the equilibrium γ. The studies here tested a series of hypotheses concerning mechanisms that might cause the late accelerated drop in γ. Experiments used captive bubbles and a Wilhelmy plate to measure γ during adsorption of vesicles containing constituents from extracted calf surfactant. The faster fall in γ reflects faster adsorption rather than any feature of the equation of state that relates γ to surface concentration (Γ). Adsorption accelerates when γ reaches a critical value rather than after an interval required to reach that γ. The hydrophobic surfactant proteins (SPs) represent key constituents, both for reaching the γ at which the acceleration occurs and for producing the acceleration itself. The γ at which rates of adsorption increase, however, is unaffected by the Γ of protein in the films. In the absence of the proteins, a phosphatidylethanolamine, which, like the SPs, induces fusion of the vesicles with the interfacial film, also causes adsorption to accelerate. Our results suggest that the late acceleration is characteristic of adsorption by fusion of vesicles with the nascent film, which proceeds more favorably when the Γ of the lipids exceeds a critical value. PMID:21417351

Low energy accelerators for research and applications

International Nuclear Information System (INIS)

Bhandari, R.K.

2013-01-01

Charged particle accelerators are instruments for producing a variety of radiations under controlled conditions for basic and applied research as well as applications. They have helped enormously to study the matter, atoms, nuclei, sub-nuclear particles and their constituents, forces involved in the related phenomena etc. No other man-made instrument has been so effective in such studies as the accelerator. The large accelerator constructed so far is the Large Hadron Collider (LHC) housed in a tunnel of 27 km circumference, while a small accelerator can fit inside a room. Small accelerators accelerate charged particles such as electrons, protons, deuterons, alphas and, in general ions to low energy, generally, below several MeV. These particle beams are used for studies in nuclear astrophysics, atomic physics, material science, surface physics, bio sciences etc. They are used for ion beam analysis such as RBS, PIXE, NRA, AMS, CPAA etc. More importantly, the ion beams have important industrial applications like ion implantation, surface modification, isotope production etc. while electron beams are used for material processing, material modification, sterilization, food preservation, non destructive testing etc. In this talk, role of low energy accelerators in research and industry as well as medicine will be discussed. (author)

PAC++: Object-oriented platform for accelerator codes

International Nuclear Information System (INIS)

Malitsky, N.; Reshetov, A.; Bourianoff, G.

1994-06-01

Software packages in accelerator physics have relatively long life cycles. They had been developed and used for a wide range of accelerators in the past as well as for the current projects. For example, the basic algorithms written in the first accelerator Program TRANSPORT are actual for design of most magnet systems. Most of these packages had been implemented on Fortran. But this language is rather inconvenient as a basic language for large integrated projects that possibly could include real-time data acquisition, data base access, graphic riser interface modules (GUI), arid other features. Some later accelerator programs had been based on object-oriented tools (primarily, C++ language). These range from systems for advanced theoretical studies to control system software. For the new generations of accelerators it would be desirable to have an integrated platform in which all simulation and control tasks will be considered with one point of view. In this report the basic principles of an object-oriented platform for accelerator research software (PAC++) are suggested and analyzed. Primary objectives of this work are to enable efficient self-explaining realization of the accelerator concepts and to provide an integrated environment for the updating and the developing of the code

Beam transport through electrostatic accelerators and matching into post accelerators

International Nuclear Information System (INIS)

Larson, J.D.

1986-01-01

Ion beam transport through electrostatic acceleration is briefly reviewed. Topics discussed include injection, matching into the low-energy acceleration stage, matching from the terminal stripper into the high-energy stage, transport to a post accelerator, space charge, bunching isochronism, dispersion and charge selection. Beam transport plans for the proposed Vivitron accelerator are described. (orig.)

Can Accelerators Accelerate Learning?

International Nuclear Information System (INIS)

Santos, A. C. F.; Fonseca, P.; Coelho, L. F. S.

2009-01-01

The 'Young Talented' education program developed by the Brazilian State Funding Agency (FAPERJ)[1] makes it possible for high-schools students from public high schools to perform activities in scientific laboratories. In the Atomic and Molecular Physics Laboratory at Federal University of Rio de Janeiro (UFRJ), the students are confronted with modern research tools like the 1.7 MV ion accelerator. Being a user-friendly machine, the accelerator is easily manageable by the students, who can perform simple hands-on activities, stimulating interest in physics, and getting the students close to modern laboratory techniques.

Can Accelerators Accelerate Learning?

Science.gov (United States)

Santos, A. C. F.; Fonseca, P.; Coelho, L. F. S.

2009-03-01

The 'Young Talented' education program developed by the Brazilian State Funding Agency (FAPERJ) [1] makes it possible for high-schools students from public high schools to perform activities in scientific laboratories. In the Atomic and Molecular Physics Laboratory at Federal University of Rio de Janeiro (UFRJ), the students are confronted with modern research tools like the 1.7 MV ion accelerator. Being a user-friendly machine, the accelerator is easily manageable by the students, who can perform simple hands-on activities, stimulating interest in physics, and getting the students close to modern laboratory techniques.

Argonne Wakefield Accelerator Update '92

International Nuclear Information System (INIS)

Rosing, M.; Balka, L.; Chojnacki, E.; Gai, W.; Ho, C.; Konecny, R.; Power, J.; Schoessow, P.; Simpson, J.

1992-01-01

The Argonne Wakefield Accelerator (AWA) is an experiment designed to test various ideas related to wakefield technology. Construction is now underway for a 100 nC electron beam in December of 1992. This report updates this progress

Minkowski spacetime does not apply to a homogeneously accelerating medium

Directory of Open Access Journals (Sweden)

Brian Coleman

Full Text Available Home and comoving inertial frame parameters of an individual point of an idealized medium of launch length L uniformly co-accelerating between identical fixed-thrust rockets, are well known. This is not the case with the varying inter-rocket radar periods and related implications regarding a changing ‘noninertial own-length’ Λ which differs from a front rocket’s retrospective separation L from the simultaneously relatively moving rear rocket. On the other hand, the nonhomogeneous acceleration case involving every comoving frame’s unchanging perception of a contrived ‘rigor mortis’ medium (so-called ‘rigid motion’ traditionally associated with ‘Rindler coordinates’ whereby Λ=L=L, constitutes the sole extended accelerating medium scenario where the entrenched Minkowski metric is actually applicable. Paraphrasing Wolfgang Pauli, not only is Minkowski spacetime not correct [in the general sense], it is not even wrong [in the restricted sense]. Keywords: Homogeneous acceleration, Radar intervals, Minkowski metric, Rigor mortis acceleration, Medium-timed photon crossing rate, Retrospective separation

Accelerations in Flight

Science.gov (United States)

Doolittle, J H

1925-01-01

This work on accelerometry was done at McCook Field for the purpose of continuing the work done by other investigators and obtaining the accelerations which occur when a high-speed pursuit airplane is subjected to the more common maneuvers. The accelerations obtained in suddenly pulling out of a dive with well-balanced elevators are shown to be within 3 or 4 per cent of the theoretically possible accelerations. The maximum acceleration which a pilot can withstand depends upon the length of time the acceleration is continued. It is shown that he experiences no difficulty under the instantaneous accelerations as high as 7.8 G., but when under accelerations in excess of 4.5 G., continued for several seconds, he quickly loses his faculties.

Theoretical Investigations of Plasma-Based Accelerators and Other Advanced Accelerator Concepts

International Nuclear Information System (INIS)

Shuets, G.

2004-01-01

Theoretical investigations of plasma-based accelerators and other advanced accelerator concepts. The focus of the work was on the development of plasma based and structure based accelerating concepts, including laser-plasma, plasma channel, and microwave driven plasma accelerators

VEDs for charged particle accelerators: Indian scenario

International Nuclear Information System (INIS)

Bhandari, R.K.

2012-01-01

In the initial times after their invention, the charged particle accelerators have, primarily, been used for fundamental studies on nuclei and atoms. From the first modern accelerator, the cathode ray tube, used by J.J. Thomson for the discovery of electron, very recently the gigantic 27 km circumference Large Hadron Collider (LHC) is operational in the search of Higg's boson and related physics issues. Particle accelerators have emerged as powerful microscopes for investigating the finest details of cells, genes, molecules, atoms, protons, neutrons, muons, electrons, quarks and, possibly, still undiscovered even more fundamental constituents of the universe, such as dark matter and dark energy. Several noble prize winning discoveries have been made using accelerators. Accelerators are now being used in a wide area of industrial and medical applications. They are used for the production of radioisotopes for medical imaging, cancer therapy, food sterilization, treatment of waste water, sterilization of medical equipment, material modification, mass spectroscopy, cargo scanning, fabrication of semiconductors etc. Ongoing effort towards the development of accelerators with megawatt beam power is showing hope for a cleaner source of nuclear energy and treatment of nuclear waste. Several tens of thousands of accelerators are presently operational in the world for basic research and applications. Development of new accelerators has several times been driven by new technologies and materials and sometimes they have driven the technological developments towards cutting edge. Some examples are ultra-high vacuum in large volumes, superfluid helium in cryogenics, cryocoolers, superconducting magnets and RF cavities, high power vacuum electronic devices, global control systems, superfast computing and communication networks, giant data storage/processing systems etc. India has been pursuing a fairly robust programme of accelerator development at various institutions. It

Extragalactic background light measurements and applications.

Science.gov (United States)

Cooray, Asantha

2016-03-01

This review covers the measurements related to the extragalactic background light intensity from γ-rays to radio in the electromagnetic spectrum over 20 decades in wavelength. The cosmic microwave background (CMB) remains the best measured spectrum with an accuracy better than 1%. The measurements related to the cosmic optical background (COB), centred at 1 μm, are impacted by the large zodiacal light associated with interplanetary dust in the inner Solar System. The best measurements of COB come from an indirect technique involving γ-ray spectra of bright blazars with an absorption feature resulting from pair-production off of COB photons. The cosmic infrared background (CIB) peaking at around 100 μm established an energetically important background with an intensity comparable to the optical background. This discovery paved the way for large aperture far-infrared and sub-millimetre observations resulting in the discovery of dusty, starbursting galaxies. Their role in galaxy formation and evolution remains an active area of research in modern-day astrophysics. The extreme UV (EUV) background remains mostly unexplored and will be a challenge to measure due to the high Galactic background and absorption of extragalactic photons by the intergalactic medium at these EUV/soft X-ray energies. We also summarize our understanding of the spatial anisotropies and angular power spectra of intensity fluctuations. We motivate a precise direct measurement of the COB between 0.1 and 5 μm using a small aperture telescope observing either from the outer Solar System, at distances of 5 AU or more, or out of the ecliptic plane. Other future applications include improving our understanding of the background at TeV energies and spectral distortions of CMB and CIB.

Electron acceleration using laser produced plasmas

CERN Multimedia

CERN. Geneva; Landua, Rolf

2005-01-01

Low density plasmas have long been of interest as a potential medium for particle acceleration since relativistic plasma waves are capable of supporting electric fields greater than 100 GeV/m. The physics of particle acceleration using plasmas will be reviewed, and new results will be discussed which have demonstrated that relatively narrow energy spread (<3%) beams having energies greater than 100 MeV can be produced from femtosecond laser plasma interactions. Future experiments and potential applications will also be discussed.

Reliability studies of a high-power proton accelerator for accelerator-driven system applications for nuclear waste transmutation

Energy Technology Data Exchange (ETDEWEB)

Burgazzi, Luciano [ENEA-Centro Ricerche ' Ezio Clementel' , Advanced Physics Technology Division, Via Martiri di Monte Sole, 4, 40129 Bologna (Italy)]. E-mail: burgazzi@bologna.enea.it; Pierini, Paolo [INFN-Sezione di Milano, Laboratorio Acceleratori e Superconduttivita Applicata, Via Fratelli Cervi 201, I-20090 Segrate (MI) (Italy)

2007-04-15

The main effort of the present study is to analyze the availability and reliability of a high-performance linac (linear accelerator) conceived for Accelerator-Driven Systems (ADS) purpose and to suggest recommendations, in order both to meet the high operability goals and to satisfy the safety requirements dictated by the reactor system. Reliability Block Diagrams (RBD) approach has been considered for system modelling, according to the present level of definition of the design: component failure modes are assessed in terms of Mean Time Between Failure (MTBF) and Mean Time To Repair (MTTR), reliability and availability figures are derived, applying the current reliability algorithms. The lack of a well-established component database has been pointed out as the main issue related to the accelerator reliability assessment. The results, affected by the conservative character of the study, show a high margin for the improvement in terms of accelerator reliability and availability figures prediction. The paper outlines the viable path towards the accelerator reliability and availability enhancement process and delineates the most proper strategies. The improvement in the reliability characteristics along this path is shown as well.

Reliability studies of a high-power proton accelerator for accelerator-driven system applications for nuclear waste transmutation

International Nuclear Information System (INIS)

Burgazzi, Luciano; Pierini, Paolo

2007-01-01

The main effort of the present study is to analyze the availability and reliability of a high-performance linac (linear accelerator) conceived for Accelerator-Driven Systems (ADS) purpose and to suggest recommendations, in order both to meet the high operability goals and to satisfy the safety requirements dictated by the reactor system. Reliability Block Diagrams (RBD) approach has been considered for system modelling, according to the present level of definition of the design: component failure modes are assessed in terms of Mean Time Between Failure (MTBF) and Mean Time To Repair (MTTR), reliability and availability figures are derived, applying the current reliability algorithms. The lack of a well-established component database has been pointed out as the main issue related to the accelerator reliability assessment. The results, affected by the conservative character of the study, show a high margin for the improvement in terms of accelerator reliability and availability figures prediction. The paper outlines the viable path towards the accelerator reliability and availability enhancement process and delineates the most proper strategies. The improvement in the reliability characteristics along this path is shown as well

Large tandem accelerators

International Nuclear Information System (INIS)

Jones, C.M.

1976-01-01

The increasing importance of energetic heavy ion beams in the study of atomic physics, nuclear physics, and materials science has partially or wholly motivated the construction of a new generation of tandem accelerators designed to operate at maximum terminal potentials in the range 14 to 30 MV. In addition, a number of older tandem accelerators are now being significantly upgraded to improve their heavy ion performance. Both of these developments have reemphasized the importance of negative heavy ion sources. The new large tandem accelerators are described, and the requirements placed on negative heavy ion source technology by these and other tandem accelerators used for the acceleration of heavy ions are discussed. First, a brief description is given of the large tandem accelerators which have been completed recently, are under construction, or are funded for construction, second, the motivation for construction of these accelerators is discussed, and last, criteria for negative ion sources for use with these accelerators are presented

Ion acceleration in the plasma source sheath

International Nuclear Information System (INIS)

Birdsall, C.K.

1986-01-01

This note is a calculation of the potential drop for a planar plasma source, across the source sheath, into a uniform plasma region defined by vector E = 0 and/or perhaps ∂ 2 PHI/∂ x 2 = 0. The calculation complements that of Bohm who obtained the potential drop at the other end of a plasma, at a planar collector sheath. The result is a relation between the source ion flux and the source sheath potential drop and the accompanying ion acceleration. This planar source sheath ion acceleration mechanism (or that from a distributed source) can provide the pre-collector-sheath ion acceleration as found necessary by Bohm. 3 refs

New developments in particle acceleration techniques. Proceedings. Vol. 2

International Nuclear Information System (INIS)

Turner, S.

1987-01-01

A Workshop organised jointly by the European Committee for Future Accelerators (ECFA), the CERN Accelerator School (CAS), the Institut National de Physique Nucleaire et de Physique des Particules (IN2P3), the Institut pour la Recherche Fondamentale/Commissariat a l'Energie Atomique (IRF/CEA) and the European Physical Society (EPS) was held at the Laboratoire de l'Accelerateur Lineaire (LAL), Orsay, from 29 June to 4 July 1987. Its purpose was to review current experimental and theoretical developments in charged-particle accelerator techniques and to address problems related to future very-high-energy machines. These proceedings contain the great majority of the papers presented at the Workshop, the corresponding questions and answers, and the round-table discussion. The principal topics were semi-conventional high-frequency linacs, transformer acceleration mechanisms, acceleration using plasma, e + e - sources, including low-emittance production and preservation, final focus and interaction point, and other new ideas. Among the latter were open accelerating structures, crystal X-ray accelerators, ferroelectrics, and acceleration using lasers. (orig.)

New developments in particle acceleration techniques. Proceedings. Vol. 1

International Nuclear Information System (INIS)

Turner, S.

1987-01-01

A Workshop organised jointly by the European Committee for Future Accelerators (ECFA), the CERN Accelerator School (CAS), the Institut National de Physique Nucleaire et de Physique des Particules (IN2P3), the Institut pour la Recherche Fondamentale/Commissariat a l'Energie Atomique (IRF/CEA) and the European Physical Society (EPS) was held at the Laboratoire de l'Accelerateur Lineaire (LAL), Orsay, from 29 June to 4 July 1987. Its purpose was to review current experimental and theoretical developments in charged-particle accelerator techniques and to address problems related to future very-high-energy machines. These proceedings contain the great majority of the papers presented at the Workshop, the corresponding questions and answers, and the round-table discussion. The principal topics were semi-conventional high-frequency linacs, transformer acceleration mechanisms, acceleration using plasma, e + e - sources including low-emittance production and preservation, final focus and interaction point, and other new ideas. Among the latter were open accelerating structures, crystal X-ray accelerators, ferroelectrics, and acceleration using lasers. (orig.)

Characteristics of Four SPE Classes According to Onset Timing and Proton Acceleration Patterns

Science.gov (United States)

Kim, Roksoon

2015-04-01

In our previous work (Kim et al., 2015), we suggested a new classification scheme, which categorizes the SPEs into four groups based on association with flare or CME inferred from onset timings as well as proton acceleration patterns using multienergy observations. In this study, we have tried to find whether there are any typical characteristics of associated events and acceleration sites in each group using 42 SPEs from 1997 to 2012. We find: (i) if the proton acceleration starts from a lower energy, a SPE has a higher chance to be a strong event (> 5000 pfu) even if the associated flare and CME are not so strong. The only difference between the SPEs associated with flare and CME is the location of the acceleration site. For the former, the sites are very low ( ~1 Rs) and close to the western limb, while the latter has a relatively higher (mean=6.05 Rs) and wider acceleration sites. (ii) When the proton acceleration starts from the higher energy, a SPE tends to be a relatively weak event (pfu), in spite of its associated CME is relatively stronger than previous group. (iii) The SPEs categorized by the simultaneous proton acceleration in whole energy range within 10 minutes, tend to show the weakest proton flux (mean=327 pfu) in spite of strong related eruptions. Their acceleration heights are very close to the locations of type II radio bursts. Based on those results, we suggest that the different characteristics of the four groups are mainly due to the different mechanisms governing the acceleration pattern and interval, and different condition such as the acceleration location.

Plasma particle accelerators

International Nuclear Information System (INIS)

Dawson, J.M.

1988-01-01

The Superconducting Supercollider (SSC) will require an 87-kilometer accelerator ring to boost particles to 40 TeV. The SSC's size is due in part to the fact that its operating principle is the same one that has dominated accelerator design for 50 years: it guides particles by means of magnetic fields and propels them by strong electric fields. If one were to build an equally powerful but smaller accelerator, one would need to increase the strength of the guiding and propelling fields. Actually, however, conventional technology may not be able to provide significant increases in field strength. There are two reasons. First, the forces from magnetic fields are becoming greater than the structural forces that hold a magnetic material together; the magnets that produce these fields would themselves be torn apart. Second, the energy from electric fields is reaching the energies that bind electrons to atoms; it would tear electrons from nuclei in the accelerator's support structures. It is the electric field problem that plasma accelerators can overcome. Plasma particle accelerators are based on the principle that particles can be accelerated by the electric fields generated within a plasma. Because the plasma has already been ionized, plasma particle accelerators are not susceptible to electron dissociation. They can in theory sustain accelerating fields thousands of times stronger that conventional technologies. So far two methods for creating plasma waves for accelerators have been proposed and tested: the wakefield and the beat wave. Although promising electric fields have been produced, more research is necessary to determine whether plasma particle accelerators can compete with the existing accelerators. 7 figs

Genetic algorithms and their applications in accelerator physics

Energy Technology Data Exchange (ETDEWEB)

Hofler, Alicia S. [JLAB

2013-12-01

Multi-objective optimization techniques are widely used in an extremely broad range of fields. Genetic optimization for multi-objective optimization was introduced in the accelerator community in relatively recent times and quickly spread becoming a fundamental tool in multi-dimensional optimization problems. This discussion introduces the basics of the technique and reviews applications in accelerator problems.

Molecular ion acceleration using tandem accelerator

Energy Technology Data Exchange (ETDEWEB)

Saito, Yuichi; Mizuhashi, Kiyoshi; Tajima, Satoshi [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

1996-12-01

In TIARA compound beam radiation system, cluster beams have been produced using 3 MV tandem accelerator (9SDH-2) to supply them to various radiation on injection experiments. Till now, productions of C{sub 2-8}, Si{sub 2-4} and O{sub 2} and their accelerations up to 6 MeV have been succeeded. This study aimed at production and acceleration of B{sub 2-4} and LiF. Anion clusters were produced using the conventional ion source of cesium sputter type. The proportions of atoms, molecules and clusters elicited from the ion source were varied depending on the material`s properties and the operating conditions of ion source such as sample temperature, sputter voltage and the shape of sample. The anion clusters were accelerated toward the high voltage terminal in the center of tandem accelerator, leading to cations through losing their electrons by the collision to N{sub 2} gas in a charge conversion cell at the terminal. Positively charged cluster ions could be obtained by modulating the pressure of N{sub 2} gas. Thus, B{sub 2} (64 nA), B{sub 3} (4.4 nA) and B{sub 4} (2.7 nA) have been produced and their maximum survival probabilities were higher than those of carbon or silicon clusters. In addition, the relationship between beam current and gas pressure was investigated for Bn (n = 2-4) and LiF. (M.N.)

TeV/m Nano-Accelerator: Current Status of CNT-Channeling Acceleration Experiment

Energy Technology Data Exchange (ETDEWEB)

Shin, Young Min [Northern Illinois U.; Lumpkin, Alex H. [Fermilab; Thangaraj, Jayakar Charles [Fermilab; Thurman-Keup, Randy Michael [Fermilab; Shiltsev, Vladimir D. [Fermilab

2014-09-17

Crystal channeling technology has offered various opportunities in the accelerator community with a viability of ultrahigh gradient (TV/m) acceleration for future HEP collider. The major challenge of channeling acceleration is that ultimate acceleration gradients might require a high power driver in the hard x-ray regime (~ 40 keV). This x-ray energy exceeds those for x-rays as of today, although x-ray lasers can efficiently excite solid plasma and accelerate particles inside a crystal channel. Moreover, only disposable crystal accelerators are possible at such high externally excited fields which would exceed the ionization thresholds destroying the atomic structure, so acceleration will take place only in a short time before full dissociation of the lattice. Carbon-based nanostructures have great potential with a wide range of flexibility and superior physical strength, which can be applied to channeling acceleration. This paper presents a beam- driven channeling acceleration concept with CNTs and discusses feasible experiments with the Advanced Superconducting Test Accelerator (ASTA) in Fermilab.

Possible connection between the location of the cutoff in the cosmic microwave background spectrum and the equation of state of dark energy.

Science.gov (United States)

Enqvist, Kari; Sloth, Martin S

2004-11-26

We investigate a possible connection between the suppression of the power at low multipoles in the cosmic microwave background (CMB) spectrum and the late time acceleration. We show that, assuming a cosmic IR/UV duality between the UV cutoff and a global infrared cutoff given by the size of the future event horizon, the equation of state of the dark energy can be related to the apparent cutoff in the CMB spectrum. The present limits on the equation of state of dark energy are shown to imply an IR cutoff in the CMB multipole interval of 9>l>8.5.

Acute myeloid leukaemia in relation to background radiation in houses

International Nuclear Information System (INIS)

Axelson, O.; Flodin, U.

1993-01-01

A review is presented on the results of several studies performed since the late 1970s to elucidate the role of background gamma radiation in houses and the incidence of cancer, especially leukemia. The influence of exposure time is discussed and the age dependence of the latency period is outlined. Estimation of dose-response relationships are presented. (MG)

A genomic background based method for association analysis in related individuals.

Directory of Open Access Journals (Sweden)

Najaf Amin

Full Text Available BACKGROUND: Feasibility of genotyping of hundreds and thousands of single nucleotide polymorphisms (SNPs in thousands of study subjects have triggered the need for fast, powerful, and reliable methods for genome-wide association analysis. Here we consider a situation when study participants are genetically related (e.g. due to systematic sampling of families or because a study was performed in a genetically isolated population. Of the available methods that account for relatedness, the Measured Genotype (MG approach is considered the 'gold standard'. However, MG is not efficient with respect to time taken for the analysis of genome-wide data. In this context we proposed a fast two-step method called Genome-wide Association using Mixed Model and Regression (GRAMMAR for the analysis of pedigree-based quantitative traits. This method certainly overcomes the drawback of time limitation of the measured genotype (MG approach, but pays in power. One of the major drawbacks of both MG and GRAMMAR, is that they crucially depend on the availability of complete and correct pedigree data, which is rarely available. METHODOLOGY: In this study we first explore type 1 error and relative power of MG, GRAMMAR, and Genomic Control (GC approaches for genetic association analysis. Secondly, we propose an extension to GRAMMAR i.e. GRAMMAR-GC. Finally, we propose application of GRAMMAR-GC using the kinship matrix estimated through genomic marker data, instead of (possibly missing and/or incorrect genealogy. CONCLUSION: Through simulations we show that MG approach maintains high power across a range of heritabilities and possible pedigree structures, and always outperforms other contemporary methods. We also show that the power of our proposed GRAMMAR-GC approaches to that of the 'gold standard' MG for all models and pedigrees studied. We show that this method is both feasible and powerful and has correct type 1 error in the context of genome-wide association analysis

Accelerator mass spectrometry at the Rossendorf 5 MV tandem accelerator

International Nuclear Information System (INIS)

Friedrich, M.; Buerger, W.; Curian, H.; Hartmann, B.; Hentschel, E.; Matthes, H.; Probst, W.; Seidel, M.; Turuc, S.; Hebert, D.; Rothe, T.; Stolz, W.

1992-01-01

The Rossendorf electrostatic accelerators (5 MV tandem accelerator and single ended 2 MV van de Graaff accelerator) are already used for ion beam analysis. The existing methods (RBS, PIXE, ERDA, NRA, nuclear microprobe and external beam) will be completed by introduction of Accelerator Mass Spectrometry (AMS). A short description of the Rossendorf AMS system is given and first experimental results are presented. (R.P.) 4 refs.; 6 figs

Truck acceleration behavior study and acceleration lane length recommendations for metered on-ramps

Directory of Open Access Journals (Sweden)

Guangchuan Yang

2016-10-01

Full Text Available This paper investigated the actual truck acceleration capability at metered on-ramps. Truck acceleration performance data were collected through a video-based data collection method. A piecewise constant acceleration model was employed to capture truck acceleration characteristics. It was found that the existing acceleration length will affect truck drivers’ acceleration behavior. At the taper type ramp that has limited acceleration distance, acceleration profile indicated a decreasing trend with distance. While for the ramp with an auxiliary lane that has sufficient acceleration distance, it was found that the acceleration behavior is to have a high acceleration rate in the beginning, then acceleration rate decrease with speed increase, and high acceleration rate again as drivers approach the merging area. Field data show that the truck acceleration performance data documented in the ITE’s (Institute of Transportation Engineers “Traffic Engineering Handbook” are much lower than the field collected data. Also, based on the regression analysis of speed versus distance profiles, it was found that the AASHTO’s (American Association of State Highway and Transportation Officials Green Book acceleration length design guidance is insufficient to accommodate trucks at metered on-ramps. The required acceleration lengths for medium and heavy trucks are approximately 1.3 and 1.6 times of the Green Book design guideline, respectively.

Accelerated subcutaneous immunotherapy in pediatric population – Systematic review

Directory of Open Access Journals (Sweden)

R.A. Gomes dos Reis Pimentel

2018-05-01

Full Text Available Background: Accelerated subcutaneous immunotherapy (SCIT schedules represent an alternative to conventional SCIT, providing immunotherapy benefits in a shorter period of time. The objectives of this systematic review were to assess clinical and immunological efficacy as well as safety of accelerated SCIT build-up schedules for the treatment of respiratory allergy in pediatric patients. Methods: Studies were located by searching PubMed, using “immunotherapy” and “desensitization” as keywords. The selection of studies, published from January 1st, 2006, to December 31th, 2015, was performed in two stages: screening of titles and abstracts, and assessment of the full papers identified as relevant, considering the inclusion criteria. Data were extracted in a standardized way and synthesized qualitatively to assess efficacy and safety of accelerated schedules in respiratory allergy. Results: Eleven trials were included: two evaluated rush SCIT and nine assessed cluster SCIT. This review demonstrated that rush and cluster schedules are clinically and immunological efficacious, with faster effect than conventional schedules. No relevant difference with respect to clinical outcomes was noticed between subgroups (pediatric, adult and mixed populations. Regarding safety, most local adverse reactions were mild and there were neither life-threatening systemic reactions nor fatal events. No relevant differences in the incidence and severity of either local or systemic reactions between the accelerated schedule group and control group were registered. Conclusions: Accelerated SCIT build-up schedules are effective in the treatment of respiratory allergy in pediatric patients, representing a safe alternative to the conventional schedules with the advantage of achieving clinical effectiveness sooner. Keywords: Allergy, Immunotherapy, Pediatrics

Determination of endogenous inflammation-related lipid mediators in ischemic stroke rats using background subtracting calibration curves by liquid chromatography-tandem mass spectrometry.

Science.gov (United States)

Yang, Yang; Zhong, Qisheng; Mo, Canlong; Zhang, Hao; Zhou, Ting; Tan, Wen

2017-11-01

Accurate and reliable quantification of endogenous lipid mediators in complex biological samples is a daunting challenge. In this study, a robust and direct endogenous quantitative method using background subtracting calibration curves by liquid chromatography-tandem mass spectrometry was first developed for the determination of endogenous lipid mediators in ischemic stroke rats. Absolute quantification without surrogate matrix could be achieved by using background subtracting calibration curves, which were corrected and verified from standard curves constructed on original matrix. The recoveries of this method were in the range of 50.3-98.3%, the precision with the relative standard deviation was less than 13.8%, and the accuracy with the relative error was within ± 15.0%. In addition, background subtracting calibration curves were further verified by validation factors ranging from 90.3 to 110.9%. This validated method has been successfully applied to the analysis of seven endogenous inflammation-related lipid mediators in the brain tissues of ischemic stroke rats. The results indicated that prostaglandins as inflammatory factors and some lipid mediators with neuroprotective effects increased apparently (p endogenous compounds in the complex biological samples. Graphical abstract The analysis procedure of determining endogenous inflammation-related lipid mediators using BSCC by LC-MS/MS.

Thailand: Background and U.S. Relations

National Research Council Canada - National Science Library

Chanlett-Avery, Emma

2006-01-01

U.S.-Thailand relations are of particular interest to Congress because of Thailand's status as a long-time military ally, a key country in the war against terrorism in Southeast Asia, and a significant...

Probing electron acceleration and x-ray emission in laser-plasma accelerators

International Nuclear Information System (INIS)

Thaury, C.; Ta Phuoc, K.; Corde, S.; Brijesh, P.; Lambert, G.; Malka, V.; Mangles, S. P. D.; Bloom, M. S.; Kneip, S.

2013-01-01

While laser-plasma accelerators have demonstrated a strong potential in the acceleration of electrons up to giga-electronvolt energies, few experimental tools for studying the acceleration physics have been developed. In this paper, we demonstrate a method for probing the acceleration process. A second laser beam, propagating perpendicular to the main beam, is focused on the gas jet few nanosecond before the main beam creates the accelerating plasma wave. This second beam is intense enough to ionize the gas and form a density depletion, which will locally inhibit the acceleration. The position of the density depletion is scanned along the interaction length to probe the electron injection and acceleration, and the betatron X-ray emission. To illustrate the potential of the method, the variation of the injection position with the plasma density is studied

''Theta gun,'' a multistage, coaxial, magnetic induction projectile accelerator

International Nuclear Information System (INIS)

Burgess, T.J.; Duggin, B.W.; Cowan, M. Jr.

1985-11-01

We experimentally and theoretically studied a multistage coaxial magnetic induction projectile accelerator. We call this system a ''theta gun'' to differentiate it from other coaxial accelerator concepts such as the mass driver. We conclude that this system can theoretically attain railgun performance only for large caliber or very high injection velocity and, even then, only for long coil geometry. Our experiments with a three-stage, capactor bank-driven accelerator are described. The experiments are modeled with a 1-1/2 dimensional equivalent circuit-hydrodynamics code which is also described. We derive an expression for the conditions of coaxial accelerator-railgun ''velocity breakeven'' in the absence of ohmic and hydrodynamic effects. This, in conjunction with an expression for the magnetic coupling coefficient, defines a set of geometric relations which the coaxial system must simultaneously satisfy. Conclusions concerning both the existence and configuration of a breakeven coaxial system follow from this requirement. The relative advantages and disadvantages of the coaxial induction projectile accelerator, previously cited in the literature, are critiqued from the viewpoint of our analysis and experimental results. We find that the advantages vis-a-vis the railgun have been overstated. 13 refs., 17 figs

Evolving Waves and Turbulence in the Outer Corona and Inner Heliosphere: The Accelerating Expanding Box

Energy Technology Data Exchange (ETDEWEB)

Tenerani, Anna; Velli, Marco [EPSS, UCLA, Los Angeles, CA (United States)

2017-07-01

Alfvénic fluctuations in the solar wind display many properties reflecting an ongoing nonlinear cascade, e.g., a well-defined spectrum in frequency, together with some characteristics more commonly associated with the linear propagation of waves from the Sun, such as the variation of fluctuation amplitude with distance, dominated by solar wind expansion effects. Therefore, both nonlinearities and expansion must be included simultaneously in any successful model of solar wind turbulence evolution. Because of the disparate spatial scales involved, direct numerical simulations of turbulence in the solar wind represent an arduous task, especially if one wants to go beyond the incompressible approximation. Indeed, most simulations neglect solar wind expansion effects entirely. Here we develop a numerical model to simulate turbulent fluctuations from the outer corona to 1 au and beyond, including the sub-Alfvénic corona. The accelerating expanding box (AEB) extends the validity of previous expanding box models by taking into account both the acceleration of the solar wind and the inhomogeneity of background density and magnetic field. Our method incorporates a background accelerating wind within a magnetic field that naturally follows the Parker spiral evolution using a two-scale analysis in which the macroscopic spatial effect coupling fluctuations with background gradients becomes a time-dependent coupling term in a homogeneous box. In this paper we describe the AEB model in detail and discuss its main properties, illustrating its validity by studying Alfvén wave propagation across the Alfvén critical point.

Local expansion flows of galaxies: quantifying acceleration effect of dark energy

Science.gov (United States)

Chernin, A. D.; Teerikorpi, P.

2013-08-01

The nearest expansion flow of galaxies observed around the Local group is studied as an archetypical example of the newly discovered local expansion flows around groups and clusters of galaxies in the nearby Universe. The flow is accelerating due to the antigravity produced by the universal dark energy background. We introduce a new acceleration measure of the flow which is the dimensionless ``acceleration parameter" Q (x) = x - x-2 depending on the normalized distance x only. The parameter is zero at the zero-gravity distance x = 1, and Q(x) ∝ x, when x ≫ 1. At the distance x = 3, the parameter Q = 2.9. Since the expansion flows have a self-similar structure in normalized variables, we expect that the result is valid as well for all the other expansion flows around groups and clusters of galaxies on the spatial scales from ˜ 1 to ˜ 10 Mpc everywhere in the Universe.

Bremsstrahlung pair-production of positrons with low neutron background

International Nuclear Information System (INIS)

Lessner, E.

1998-01-01

Minimization of component activation is highly desirable at accelerator-based positron sources. Electrons in the 8- to 14-MeV energy range impinging on a target produce photons energetic enough to create electron-positron pairs; however, few of the photons are energetic enough to produce photoneutrons. Slow positron production by low-energy electrons impinging on a multilayer tungsten target with and without electromagnetic extraction between the layers was studied by simulation. The neutron background from 14-MeV electrons is expected to be significantly lower than that encountered with higher-energy electron beams. Numerical results are presented and some ideas for a low-activation slow-positron source are discussed

State registration and inspection programs for particle accelerators

International Nuclear Information System (INIS)

Bailey, E.D.

1976-01-01

The Suggested State Regulations for Control of Radiation(SSRCR) are recommended by the Council of State Governments and the National Conference of Radiation Control Program Directors as the model regulations which states should adopt in order to have adequate regulation and uniformity from state to state. These regulations are used as a basis for reviewing the current status of accelerator regulation in each state. The SSRCR does contain a separate part for registration (Part B--Registration of Radiation Machine Facilities and Services) and a separate part (Part I--Radiation Safety Requirements for Particle Accelerators) with specific requirements for the possession and use of accelerators. In addition, medical accelerators have additional requirements in Part F--X-Rays in The Heating Acts. These regulations specify requirements related to limitations of use, shielding and safety design requirements, control and interlock systems, warning devices, operating procedures, radiation monitoring, and calibration of medical accelerators

Microelectromechanical acceleration-sensing apparatus

Science.gov (United States)

Lee, Robb M [Albuquerque, NM; Shul, Randy J [Albuquerque, NM; Polosky, Marc A [Albuquerque, NM; Hoke, Darren A [Albuquerque, NM; Vernon, George E [Rio Rancho, NM

2006-12-12

An acceleration-sensing apparatus is disclosed which includes a moveable shuttle (i.e. a suspended mass) and a latch for capturing and holding the shuttle when an acceleration event is sensed above a predetermined threshold level. The acceleration-sensing apparatus provides a switch closure upon sensing the acceleration event and remains latched in place thereafter. Examples of the acceleration-sensing apparatus are provided which are responsive to an acceleration component in a single direction (i.e. a single-sided device) or to two oppositely-directed acceleration components (i.e. a dual-sided device). A two-stage acceleration-sensing apparatus is also disclosed which can sense two acceleration events separated in time. The acceleration-sensing apparatus of the present invention has applications, for example, in an automotive airbag deployment system.

Commissioning the GTA accelerator

International Nuclear Information System (INIS)

Sander, O.R.; Atkins, W.H.; Bolme, G.O.; Bowling, S.; Brown, S.; Cole, R.; Gilpatrick, J.D.; Garnett, R.; Guy, F.W.; Ingalls, W.B.; Johnson, K.F.; Kerstiens, D.; Little, C.; Lohsen, R.A.; Lloyd, S.; Lysenko, W.P.; Mottershead, C.T.; Neuschaefer, G.; Power, J.; Rusthoi, D.P.; Sandoval, D.P. Stevens, R.R. Jr.; Vaughn, G.; Wadlinger, E.A.; Yuan, V.; Connolly, R.; Weiss, R.; Saadatmand, K.

1992-01-01

The Ground Test Accelerator (GTA) is supported by the Strategic Defense command as part of their Neutral Particle Beam (NPB) program. Neutral particles have the advantage that in space they are unaffected by the earth's magnetic field and travel in straight lines unless they enter the earth's atmosphere and become charged by stripping. Heavy particles are difficult to stop and can probe the interior of space vehicles; hence, NPB can function as a discriminator between warheads and decoys. We are using GTA to resolve the physics and engineering issues related to accelerating, focusing, and steering a high-brightness, high-current H - beam and then neutralizing it. Our immediate goal is to produce a 24-MeV, 50mA device with a 2% duty factor

Accelerators for cancer therapy

International Nuclear Information System (INIS)

Lennox, Arlene J.

2000-01-01

The vast majority of radiation treatments for cancerous tumors are given using electron linacs that provide both electrons and photons at several energies. Design and construction of these linacs are based on mature technology that is rapidly becoming more and more standardized and sophisticated. The use of hadrons such as neutrons, protons, alphas, or carbon, oxygen and neon ions is relatively new. Accelerators for hadron therapy are far from standardized, but the use of hadron therapy as an alternative to conventional radiation has led to significant improvements and refinements in conventional treatment techniques. This paper presents the rationale for radiation therapy, describes the accelerators used in conventional and hadron therapy, and outlines the issues that must still be resolved in the emerging field of hadron therapy

Channel-accelerating gap interaction and beam acceleration and transport experiments with the recirculating linear accelerator (RLA)

International Nuclear Information System (INIS)

Mazarakis, M.G.; Smith, D.L.; Poukey, J.W.; Wagner, J.S.; Bennett, L.F.; Olson, W.R.; Turman, B.N.; Prestwich, K.R.; Wells, J.; Struve, K.

1992-01-01

The lifetime of the Ion Focusing Regime (IFR) channel following the pulsing of the post-accelerating gaps is critical for open-ended low energy devices. It dictates the number of allowable beam recirculations through the gaps. In the case of a closed racetrack configuration, it is significant but not as critical, since the presence of the electron beam focuses the ions and lengthens the lifetime of the ion channel. The authors have experimentally established that pulsing an accelerating gap perturbs the IFR channel. However for the parameters studied, the lifetime is long enough to allow at least four beam recirculations in a spiral device. In addition transparent grids of cusp fields positioned upstream and downstream from the gaps prevent them from perturbing the IFR channel. Experiments were performed with and without injected electron beams. For the experiments investigating the IFR channel interaction with the accelerating gap, the injector was removed and the beam line was extended downstream and upstream from the accelerating cavity. Only the first straight section of the RLA with one accelerating cavity (ET-2) was utilized. The acceleration and transport experiments were performed utilizing two injectors: first the low energy 1.3-MV Isolated Blumlein (IB) injector and most recently the new 4-MV 20-kA injector. Beams of 6--20 kA current were produced and successfully transported and accelerated through the ET-2 post-accelerating gap. For both injectors an apertured non-immersed ion-focused foilless diode was selected among various options. It is the simplest and easiest to operate and can be adjusted to provide variable beam impedance loads to the injector. The transport efficiencies were 90% for the low energy injector and 100% for the new 4-MV injector. The beam Gaussian profile and radius (5 mm) remain the same through acceleration. Experimental results will be presented and compared with numerical simulations

Accelerator reliability workshop

International Nuclear Information System (INIS)

Hardy, L.; Duru, Ph.; Koch, J.M.; Revol, J.L.; Van Vaerenbergh, P.; Volpe, A.M.; Clugnet, K.; Dely, A.; Goodhew, D.

2002-01-01

About 80 experts attended this workshop, which brought together all accelerator communities: accelerator driven systems, X-ray sources, medical and industrial accelerators, spallation sources projects (American and European), nuclear physics, etc. With newly proposed accelerator applications such as nuclear waste transmutation, replacement of nuclear power plants and others. Reliability has now become a number one priority for accelerator designers. Every part of an accelerator facility from cryogenic systems to data storage via RF systems are concerned by reliability. This aspect is now taken into account in the design/budget phase, especially for projects whose goal is to reach no more than 10 interruptions per year. This document gathers the slides but not the proceedings of the workshop

Accelerator reliability workshop

Energy Technology Data Exchange (ETDEWEB)

Hardy, L; Duru, Ph; Koch, J M; Revol, J L; Van Vaerenbergh, P; Volpe, A M; Clugnet, K; Dely, A; Goodhew, D

2002-07-01

About 80 experts attended this workshop, which brought together all accelerator communities: accelerator driven systems, X-ray sources, medical and industrial accelerators, spallation sources projects (American and European), nuclear physics, etc. With newly proposed accelerator applications such as nuclear waste transmutation, replacement of nuclear power plants and others. Reliability has now become a number one priority for accelerator designers. Every part of an accelerator facility from cryogenic systems to data storage via RF systems are concerned by reliability. This aspect is now taken into account in the design/budget phase, especially for projects whose goal is to reach no more than 10 interruptions per year. This document gathers the slides but not the proceedings of the workshop.

Advanced age-related denervation and fiber-type grouping in skeletal muscle of SOD1 knockout mice.

Science.gov (United States)

Kostrominova, Tatiana Y

2010-11-30

In this study skeletal muscles from 1.5- and 10-month-old Cu/Zn superoxide dismutase (SOD1) homozygous knockout (JLSod1(-/-)) mice obtained from The Jackson Laboratory (C57Bl6/129SvEv background) were compared with muscles from age- and sex-matched heterozygous (JLSod1(+/-)) littermates. The results of this study were compared with previously published data on two different strains of Sod1(-/-) mice: one from Dr. Epstein's laboratory (ELSod1(-/-); C57Bl6 background) and the other from Cephalon, Inc. (CSod1(-/-); 129/CD-1 background). Grouping of succinate dehydrogenase-positive fibers characterized muscles of Sod1(-/-) mice from all three strains. The 10-month-old Sod1(-/-)C and JL mice displayed pronounced denervation of the gastrocnemius muscle, whereas the ELSod1(-/-) mice displayed a small degree of denervation at this age, but developed accelerated age-related denervation later on. Denervation markers were up-regulated in skeletal muscle of 10-month-old JLSod1(-/-) mice. This study is the first to show that metallothionein mRNA and protein expression was up-regulated in the skeletal muscle of 10-month-old JLSod1(-/-) mice and was mostly localized to the small atrophic muscle fibers. In conclusion, all three strains of Sod1(-/-) mice develop accelerated age-related muscle denervation, but the genetic background has significant influence on the progress of denervation. Copyright © 2010 Elsevier Inc. All rights reserved.

Future accelerator technology

International Nuclear Information System (INIS)

Sessler, A.M.

1986-05-01

A general discussion is presented of the acceleration of particles. Upon this foundation is built a categorization scheme into which all accelerators can be placed. Special attention is devoted to accelerators which employ a wake-field mechanism and a restricting theorem is examined. It is shown how the theorem may be circumvented. Comments are made on various acceleration schemes

Comparison of impact forces, accelerations and ankle range of motion in surfing-related landing tasks.

Science.gov (United States)

Lundgren, Lina E; Tran, Tai T; Nimphius, Sophia; Raymond, Ellen; Secomb, Josh L; Farley, Oliver R L; Newton, Robert U; Sheppard, Jeremy M

2016-01-01

This study aimed to describe the impact forces, accelerations and ankle range of motion in five different landing tasks that are used in training and testing for competitive surfing athletes, to assist coaches in the prescription of landing task progression and monitoring training load. Eleven competitive surfing athletes aged 24 ± 7 years participated, and inertial motion sensors were fixed to the anterior aspect of the feet, mid-tibial shafts, sacrum and eighth thoracic vertebrae on these athletes. Three tasks were performed landing on force plates and two tasks in a modified gymnastics set-up used for land-based aerial training. Peak landing force, resultant peak acceleration and front and rear side ankle dorsiflexion ranges of motion during landing were determined. The peak acceleration was approximately 50% higher when performing aerial training using a mini-trampoline and landing on a soft-density foam board, compared to a similar landing off a 50 cm box. Furthermore, the ankle ranges of motion during the gymnastic type landings were significantly lower than the other landing types (P ≤ 0.05 and P ≤ 0.001), for front and rear sides, respectively. Conclusively, increased task complexity and specificity of the sport increased the tibial peak acceleration, indicating greater training load.

Requirements of a proton beam accelerator for an accelerator-driven reactor

International Nuclear Information System (INIS)

Takahashi, H.; Zhao, Y.; Tsoupas, N.; An, Y.; Yamazaki, Y.

1997-01-01

When the authors first proposed an accelerator-driven reactor, the concept was opposed by physicists who had earlier used the accelerator for their physics experiments. This opposition arose because they had nuisance experiences in that the accelerator was not reliable, and very often disrupted their work as the accelerator shut down due to electric tripping. This paper discusses the requirements for the proton beam accelerator. It addresses how to solve the tripping problem and how to shape the proton beam

SLAC accelerator operations report: 1995--1997

International Nuclear Information System (INIS)

Erickson, R.; Allen, C.W.; Anderson, S.; Linebarger, W.; Stanek, M.

1997-05-01

Operational statistics for the linear accelerator programs at SLAC are presented, including run-time records for SLC and the fixed-target programs. Also included are summaries of reliability and maintenance-related statistics

Licensing criteria for particle accelerators categorization

International Nuclear Information System (INIS)

Costa, Evaldo L.C. da

2013-01-01

From the international experience of research centers in various parts of the world, where there are particle accelerators of various sizes and energies, it was found that operating energy of particle accelerators is one of the parameters used by categorization models in the licensing of these radiation facilities, and the facility size is an important aspect to be considered in this model. A categorization based on these two key parameters is presented, also taking into account the kinds of accelerated particles and radiation produced, the operating related technology and the possible applications concerned. The categorization models of national nuclear authorities of five countries are reviewed, emphasizing the contribution of Brazil, and the new model proposed is also based on the experience of these countries, modified by those two parameter discussed above: facility size and operating energy of particle accelerators. Later, some changes are suggested, considering risk factors and safety features related to these facilities, emphasizing some analytical tools commonly used in nuclear facilities and chemical plants, such as: risk-informing decision making, layer of protection analysis (LOPRA) and safety integrity levels (SIL), the two latter ones having its origin in the broader concept of system safety. We also discuss the problem of scarcity of reliability data (common in the analyses involving risk factors and safety), due to security concerns and other factors, being the possible alternative solutions the use of generic databases and the adoption of reference facilities that provide partial data publicly. (author).

Licensing criteria for particle accelerators categorization

Energy Technology Data Exchange (ETDEWEB)

Costa, Evaldo L.C. da, E-mail: evaldo@cnen.gov.br [Comissao Nacional de Energia Nuclear (CNEN-RJ), Rio de Janeiro, RJ (Brazil). Dir. de Radioprotecao e Seguranca; Melo, Paulo F.F. Frutuoso e, E-mail: frutuoso@nuclear.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil)

2013-07-01

From the international experience of research centers in various parts of the world, where there are particle accelerators of various sizes and energies, it was found that operating energy of particle accelerators is one of the parameters used by categorization models in the licensing of these radiation facilities, and the facility size is an important aspect to be considered in this model. A categorization based on these two key parameters is presented, also taking into account the kinds of accelerated particles and radiation produced, the operating related technology and the possible applications concerned. The categorization models of national nuclear authorities of five countries are reviewed, emphasizing the contribution of Brazil, and the new model proposed is also based on the experience of these countries, modified by those two parameter discussed above: facility size and operating energy of particle accelerators. Later, some changes are suggested, considering risk factors and safety features related to these facilities, emphasizing some analytical tools commonly used in nuclear facilities and chemical plants, such as: risk-informing decision making, layer of protection analysis (LOPRA) and safety integrity levels (SIL), the two latter ones having its origin in the broader concept of system safety. We also discuss the problem of scarcity of reliability data (common in the analyses involving risk factors and safety), due to security concerns and other factors, being the possible alternative solutions the use of generic databases and the adoption of reference facilities that provide partial data publicly. (author).

Ablation plume dynamics in a background gas

DEFF Research Database (Denmark)

Amoruso, Salvatore; Schou, Jørgen; Lunney, James G.

2010-01-01

The expansion of a plume in a background gas of pressure comparable to that used in pulsed laser deposition (PLD) has been analyzed in terms of the model of Predtechensky and Mayorov (PM). This approach gives a relatively clear and simple description of the essential hydrodynamics during the expa......The expansion of a plume in a background gas of pressure comparable to that used in pulsed laser deposition (PLD) has been analyzed in terms of the model of Predtechensky and Mayorov (PM). This approach gives a relatively clear and simple description of the essential hydrodynamics during...... the expansion. The model also leads to an insightful treatment of the stopping behavior in dimensionless units for plumes and background gases of different atomic/molecular masses. The energetics of the plume dynamics can also be treated with this model. Experimental time-of-flight data of silver ions in a neon...... background gas show a fair agreement with predictions from the PM-model. Finally we discuss the validity of the model, if the work done by the pressure of the background gas is neglected....

Advanced accelerator research and development

International Nuclear Information System (INIS)

Anon.

1974-01-01

Research and development on the Positron-Electron Project (PEP), the electron rings, the superconducting accelerator (ESCAR), and the superconductivity program are reported. Efforts relating to the proposed PEP include work on: (1) the injection system; (2) the rf system; (3) the main-ring bend magnets; (4) the magnet power supplies and controls; (5) alignment; (6) radiation and shielding; (7) the vacuum system; and (8) conventional facilities (utilities, etc.). Experimental and theoretical work continued on the development of suitably intense electron rings as vehicles for the collective acceleration of ions. The most difficult problem was found to be the longitudinal (negative mass) instability. Design work was begun for ESCAR (Experimental Superconducting Accelerating Ring), a small proton synchrotron and storage ring using superconducting magnets, which should aid in the design of future large superconducting facilities. Magnet development was largely directed toward the detailed design of the dipole units. A superconducting beam transport line was installed at the Bevatron. (PMA)

SALOME: An Accelerator for the Practical Course in Accelerator Physics

OpenAIRE

Miltchev, Velizar; Riebesehl, Daniel; Roßbach, Jörg; Trunk, Maximilian; Stein, Oliver

2014-01-01

SALOME (Simple Accelerator for Learning Optics and the Manipulation of Electrons) is a short low energy linear electron accelerator built by the University of Hamburg. The goal of this project is to give the students the possibility to obtain hands-on experience with the basics of accelerator physics. In this contribution the layout of the device will be presented. The most important components of the accelerator will be discussed and an overview of the planned demonstration experiments will ...

The miniature accelerator

CERN Multimedia

Antonella Del Rosso

2015-01-01

The image that most people have of CERN is of its enormous accelerators and their capacity to accelerate particles to extremely high energies. But thanks to some cutting-edge studies on beam dynamics and radiofrequency technology, along with innovative construction techniques, teams at CERN have now created the first module of a brand-new accelerator, which will be just 2 metres long. The potential uses of this miniature accelerator will include deployment in hospitals for the production of medical isotopes and the treatment of cancer. It’s a real David-and-Goliath story.   Serge Mathot, in charge of the construction of the "mini-RFQ", pictured with the first of the four modules that will make up the miniature accelerator. The miniature accelerator consists of a radiofrequency quadrupole (RFQ), a component found at the start of all proton accelerator chains around the world, from the smallest to the largest. The LHC is designed to produce very high-intensity beams ...

Measurement of radioactivity in air at the linear accelerator of Kyoto University reactor facility

International Nuclear Information System (INIS)

Ikebe, Yukimasa; Shimo, Michikuni

1976-01-01

It is well-known that the induced activities from a number of nuclides are generated in air during the operation of high energy accelerators. Of these, measurements were performed with the linear accelerator of Kyoto University reactor facility for the purpose of the clarification of the production mechanism and behavior of radioactive aerosols. The concentration in air and the size distribution of 13 N aerosols which have aerosols as the carrier among 13 N produced by the γ-n reaction of 14 N were measured with filter packs and by diffusion method, respectively. The density of number and size distribution of non-radioactive aerosols were measured to understand the production mechanism and behavior of 13 N aerosols. For the aerosol number density, Aitken nucleus number was measured with a Pollak counter. The results obtained show that (1) under the operating condition of the linear accelerator at that measurement time, 13 N aerosol concentration was (2 to 50) x 10 -13 Ci/cm 3 while 13 N gas component concentration was (1 to 25) x 10 -12 Ci/cm 3 , i.e. the ratio was approximately 1 : 10 (2) the average size of 13 N aerosols was 0.01 to 0.04 μm, and it was found that there was positive correlation to relative humidity; (3) during the operation of the accelerator, the generation of aerosols 10 to 100 times as much as the background level was observed. The size distribution of aerosols showed a peak around 0.01 μm; and others. Examination was carried out regarding a 13 N aerosol production model based on the sticking of aerosol-free 13 N to aerosols. (Wakatsuki, Y.)

MHD accelerated motion on a body placed symmetrical to the flow in the presence of transverse magnetic field fixed relative to the body

International Nuclear Information System (INIS)

Goyal, Mamta; Bansal, J.L.

1993-01-01

The growth of the boundary layer in an accelerated flow of an electricity conducting fluid past a symmetrical placed body in the presence of uniform transverse magnetic field fixed relative to the body has been studied. The boundary layer equation has been solved by using a method previously developed by Pozzi, based on expressing the unknown velocity in term of an error function and on using differential and integral relations obtained from the balance equation. As examples, the impulsive flow past a circular cylinder and uniformly accelerated flow over a flat plate are considered. It is found that the effect of the magnetic field is to decelerate the fluid motion which results in an earlier boundary layer separation in the impulsive flow past a circular cylinder. The results show a good agreement with the numerical data available in the literature. (author). 30 refs., 4 figs., 2 tabs

Electron pulse shaping in the FELIX RF accelerator

International Nuclear Information System (INIS)

Weits, H.H.; Geer, C.A.J. van der; Oepts, D.; Meer, A.F.G. van der

1999-01-01

The FELIX free-electron laser uses short pulses of relativistic electrons produced by an RF accelerator. The design target for the duration of these electron bunches was around 3 ps. In experiments we observed that the bunches emit coherently enhanced spontaneous emission (CSE) when they travel through an undulator. It was demonstrated that the power level of the CSE critically depends on the settings of the accelerator. In this article we seek to explain these observations by studying the length and shape of the electron bunches as a function of the settings of the accelerator. A particle-tracking model was used to simulate the acceleration and transport processes. These include bunch compression in a 14-cell travelling wave buncher cavity, acceleration in a travelling wave linear accelerator, and passage through a (dispersive) chicane structure. The effect of the phase setting of the RF accelerating field with respect to the arrival time of the electron bunch in each accelerator structure was studied. The parameter range of the simulations is related to that of an actual free-electron laser experiment using these bunches. We find that, for specific settings of the accelerating system, electron pulses with a length of 350 μm FWHM (1 ps) are produced. The charge in the bunch rises steeply within a distance of 25 μm. This bunch shape explains the high level of coherently enhanced spontaneous emission observed in the FELIX laser. (author)

Tunnel flexibility effect on the ground surface acceleration response

Science.gov (United States)

Baziar, Mohammad Hassan; Moghadam, Masoud Rabeti; Choo, Yun Wook; Kim, Dong-Soo

2016-09-01

Flexibility of underground structures relative to the surrounding medium, referred to as the flexibility ratio, is an important factor that influences their dynamic interaction. This study investigates the flexibility effect of a box-shaped subway tunnel, resting directly on bedrock, on the ground surface acceleration response using a numerical model verified against dynamic centrifuge test results. A comparison of the ground surface acceleration response for tunnel models with different flexibility ratios revealed that the tunnels with different flexibility ratios influence the acceleration response at the ground surface in different ways. Tunnels with lower flexibility ratios have higher acceleration responses at short periods, whereas tunnels with higher flexibility ratios have higher acceleration responses at longer periods. The effect of the flexibility ratio on ground surface acceleration is more prominent in the high range of frequencies. Furthermore, as the flexibility ratio of the tunnel system increases, the acceleration response moves away from the free field response and shifts towards the longer periods. Therefore, the flexibility ratio of the underground tunnels influences the peak ground acceleration (PGA) at the ground surface, and may need to be considered in the seismic zonation of urban areas.

Electrostatic accelerators

OpenAIRE

Hinterberger, F

2006-01-01

The principle of electrostatic accelerators is presented. We consider Cockcroft– Walton, Van de Graaff and Tandem Van de Graaff accelerators. We resume high voltage generators such as cascade generators, Van de Graaff band generators, Pelletron generators, Laddertron generators and Dynamitron generators. The speci c features of accelerating tubes, ion optics and methods of voltage stabilization are described. We discuss the characteristic beam properties and the variety of possible beams. We ...

Superconducting accelerator technology

International Nuclear Information System (INIS)

Grunder, H.A.; Hartline, B.K.

1986-01-01

Modern and future accelerators for high energy and nuclear physics rely increasingly on superconducting components to achieve the required magnetic fields and accelerating fields. This paper presents a practical overview of the phenomenon of superconductivity, and describes the design issues and solutions associated with superconducting magnets and superconducting rf acceleration structures. Further development and application of superconducting components promises increased accelerator performance at reduced electric power cost

Sector ring accelerator ''RESATRON''

International Nuclear Information System (INIS)

Schwabe, E.

1980-01-01

Project of sector ring accelerator RESATRON is described. The curiosity of this accelerator is the second cycle of acceleration of the beam after stripping it on the foil. In such an accelerator heavy ions with a different ratio Z to A can be accelerated. (S.B.)

Comparing joint kinematics and center of mass acceleration as feedback for control of standing balance by functional neuromuscular stimulation

Directory of Open Access Journals (Sweden)

Nataraj Raviraj

2012-05-01

Full Text Available Abstract Background The purpose of this study was to determine the comparative effectiveness of feedback control systems for maintaining standing balance based on joint kinematics or total body center of mass (COM acceleration, and assess their clinical practicality for standing neuroprostheses after spinal cord injury (SCI. Methods In simulation, controller performance was measured according to the upper extremity effort required to stabilize a three-dimensional model of bipedal standing against a variety of postural disturbances. Three cases were investigated: proportional-derivative control based on joint kinematics alone, COM acceleration feedback alone, and combined joint kinematics and COM acceleration feedback. Additionally, pilot data was collected during external perturbations of an individual with SCI standing with functional neuromuscular stimulation (FNS, and the resulting joint kinematics and COM acceleration data was analyzed. Results Compared to the baseline case of maximal constant muscle excitations, the three control systems reduced the mean upper extremity loading by 51%, 43% and 56%, respectively against external force-pulse perturbations. Controller robustness was defined as the degradation in performance with increasing levels of input errors expected with clinical deployment of sensor-based feedback. At error levels typical for body-mounted inertial sensors, performance degradation due to sensor noise and placement were negligible. However, at typical tracking error levels, performance could degrade as much as 86% for joint kinematics feedback and 35% for COM acceleration feedback. Pilot data indicated that COM acceleration could be estimated with a few well-placed sensors and efficiently captures information related to movement synergies observed during perturbed bipedal standing following SCI. Conclusions Overall, COM acceleration feedback may be a more feasible solution for control of standing with FNS given its

2014 Joint International Accelerator School: Beam Loss and Accelerator Protection

CERN Document Server

JAS - Joint US-CERN-Japan-Russia Accelerator School

2016-01-01

Many particle accelerators operate with very high beam power and very high energy stored in particle beams as well as in magnet systems. In the future, the beam power in high intensity accelerators will further increase. The protection of the accelerator equipment from the consequences of uncontrolled release of the energy is essential. This was the motivation for organizing a first school on beam losses and accelerator protection (in general referred to as machine protection). During the school the methods and technologies to identify, mitigate, monitor and manage the technical risks associated with the operation of accelerators with high-power beams or subsystems with large stored energy were presented. At the completion of the school the participants should have been able to understand the physical phenomena that can damage machine subsystems or interrupt operations and to analyze an accelerator facility to produce a register of technical risks and the corresponding risk mitigation and management strategie...

Physics of Neutralization of Intense Charged Particle Beam Pulses by a Background Plasma

International Nuclear Information System (INIS)

Kaganovich, I.D.; Davidson, R.C.; Dorf, M.A.; Startsev, E.A.; Sefkow, A.B; Friedman, A.F.; Lee, E.P.

2009-01-01

Neutralization and focusing of intense charged particle beam pulses by a background plasma forms the basis for a wide range of applications to high energy accelerators and colliders, heavy ion fusion, and astrophysics. For example, for ballistic propagation of intense ion beam pulses, background plasma can be used to effectively neutralize the beam charge and current, so that the self-electric and self-magnetic fields do not affect the ballistic propagation of the beam. From the practical perspective of designing advanced plasma sources for beam neutralization, a robust theory should be able to predict the self-electric and self-magnetic fields during beam propagation through the background plasma. The major scaling relations for the self-electric and self-magnetic fields of intense ion charge bunches propagating through background plasma have been determined taking into account the effects of transients during beam entry into the plasma, the excitation of collective plasma waves, the effects of gas ionization, finite electron temperature, and applied solenoidal and dipole magnetic fields. Accounting for plasma production by gas ionization yields a larger self-magnetic field of the ion beam compared to the case without ionization, and a wake of current density and self-magnetic field perturbations is generated behind the beam pulse. A solenoidal magnetic field can be applied for controlling the beam propagation. Making use of theoretical models and advanced numerical simulations, it is shown that even a small applied magnetic field of about 100G can strongly affect the beam neutralization. It has also been demonstrated that in the presence of an applied magnetic field the ion beam pulse can excite large-amplitude whistler waves, thereby producing a complex structure of self-electric and self-magnetic fields. The presence of an applied solenoidal magnetic field may also cause a strong enhancement of the radial self-electric field of the beam pulse propagating

Linear Accelerators

International Nuclear Information System (INIS)

Vretenar, M

2014-01-01

The main features of radio-frequency linear accelerators are introduced, reviewing the different types of accelerating structures and presenting the main characteristics aspects of linac beam dynamics

Electrostatic Plasma Accelerator (EPA)

Science.gov (United States)

Brophy, John R.; Aston, Graeme

1995-01-01

The application of electric propulsion to communications satellites, however, has been limited to the use of hydrazine thrusters with electric heaters for thrust and specific impulse augmentation. These electrothermal thrusters operate at specific impulse levels of approximately 300 s with heater powers of about 500 W. Low power arcjets (1-3 kW) are currently being investigated as a way to increase specific impulse levels to approximately 500 s. Ion propulsion systems can easily produce specific impulses of 3000 s or greater, but have yet to be applied to communications satellites. The reasons most often given for not using ion propulsion systems are their high level of overall complexity, low thrust with long burn times, and the difficulty of integrating the propulsion system into existing commercial spacecraft busses. The Electrostatic Plasma Accelerator (EPA) is a thruster concept which promises specific impulse levels between low power arcjets and those of the ion engine while retaining the relative simplicity of the arcjet. The EPA thruster produces thrust through the electrostatic acceleration of a moderately dense plasma. No accelerating electrodes are used and the specific impulse is a direct function of the applied discharge voltage and the propellant atomic mass.

Accelerator structure for a charged particle linear accelerator working in standing wave mode

International Nuclear Information System (INIS)

Tran, D.T.; Tronc, Dominique.

1977-01-01

Charged particle accelerators generally include a pre-grouping or pre-accelerating structure associated with the accelerator structure itself. But pre-grouping or pre-accelerating structures of known type (Patent application No. 70 39261 for example) present electric and dimensional characteristics that rule them out for accelerators working at high frequencies (C or X bands for example), since the distance separating the interaction spaces becomes very small in this case. The accelerator structure mentioned in this invention can be used to advantage for such accelerators [fr

Injection Related Background due to the Transverse Feedback

International Nuclear Information System (INIS)

Decker, F.J.; Akre, R.; Fisher, A.; Iverson, R.; Weaver, M.

2008-01-01

The background in the BaBar detector is especially high during injection, when most components are actually having reduced voltages. The situation is worse for the beam in High Energy Ring (HER) when the LER beam is present. It was found that the transverse feedback system plays an important role when stacking more charge on top of existing bunches. Lowering the feedback gain helped and it was realized later that the best scenario would be to gate off the feedback for only the one bunch, which got additional charge injected into it. The explanation is that the blown-up, but centered, original HER bunch plus the small injected off-axis bunch (each with half the charge) would stay in the ring if not touched, but the feedback system sees half the offset and wants to correct it, therefore disturbing and scraping the blown-up part

Development of bipolar pulse accelerator for intense pulsed ion beam acceleration

International Nuclear Information System (INIS)

Fujioka, Y.; Mitsui, C.; Kitamura, I.; Takahashi, T.; Masugata, K.; Tanoue, H.; Arai, K.

2003-01-01

To improve the purity of an intense pulsed ion beams a new type of pulsed ion beam accelerator named 'bipolar pulse accelerator (BPA)' was proposed. In the accelerator purity of the beam is expected. To confirm the principle of the accelerator experimental system was developed. The system utilizes B y type magnetically insulated acceleration gap and operated with single polar negative pulse. A coaxial gas puff plasma gun placed in the grounded anode was used as an ion source, and source plasma (nitrogen) of current density approx. = 25 A/cm 2 , duration approx. = 1.5 μs was injected into the acceleration gap. The ions are successfully accelerated from the grounded anode to the drift tube by applying negative pulse of voltage 180 kV, duration 60 ns to the drift tube. Pulsed ion beam of current density approx. = 40 A/cm 2 , duration approx. 60 ns was obtained at 42 mm downstream from the anode surface. (author)

Age-Related Macular Degeneration: Pathogenesis, Genetic Background, and the Role of Nutritional Supplements

Directory of Open Access Journals (Sweden)

Marilita M. Moschos

2014-01-01

Full Text Available Age-related macular degeneration (ARMD is the leading cause of severe vision loss and blindness worldwide, mainly affecting people over 65 years old. Dry and wet ARDM are the main types of the disease, which seem to have a multifactorial background. The aim of this review is to summarize the mechanisms of ARMD pathogenesis and exhibit the role of diet and nutritional supplements in the onset and progression of the disease. Environmental factors, such as smoking, alcohol, and, diet appear to interact with mutations in nuclear and mitochondrial DNA, contributing to the pathogenesis of ARMD. Inflammatory mediators and oxidative stress, induced by the daily exposure of retina to high pressure of oxygen and light radiation, have been also associated with ARMD lesions. Other than medical and surgical therapies, nutritional supplements hold a significant role in the prevention and treatment of ARMD, eliminating the progression of macular degeneration.

Effects of background radiation

International Nuclear Information System (INIS)

Knox, E.G.; Stewart, A.M.; Gilman, E.A.; Kneale, G.W.

1987-01-01

The primary objective of this investigation is to measure the relationship between exposure to different levels of background gamma radiation in different parts of the country, and different Relative Risks for leukaemias and cancers in children. The investigation is linked to an earlier analysis of the effects of prenatal medical x-rays upon leukaemia and cancer risk; the prior hypothesis on which the background-study was based, is derived from the earlier results. In a third analysis, the authors attempted to measure varying potency of medical x-rays delivered at different stages of gestation and the results supply a link between the other two estimates. (author)

Heating and acceleration of solar wind ions by turbulent wave spectrum in inhomogeneous expanding plasma

Energy Technology Data Exchange (ETDEWEB)

Ofman, Leon, E-mail: Leon.Ofman@nasa.gov [Department of Physics, The Catholic University of America, Washington, DC (United States); NASA Goddard Space Flight Center, Greenbelt, MD (United States); Visiting, Department of Geosciences, Tel Aviv University, Tel Aviv (Israel); Ozak, Nataly [Centre for mathematical Plasma Astrophysics, KU Leuven, Celestijnenlaan 200B, 3001 Leuven (Belgium); Viñas, Adolfo F. [NASA Goddard Space Flight Center, Greenbelt, MD (United States)

2016-03-25

Near the Sun (< 10R{sub s}) the acceleration, heating, and propagation of the solar wind are likely affected by the background inhomogeneities of the magnetized plasma. The heating and the acceleration of the solar wind ions by turbulent wave spectrum in inhomogeneous plasma is studied using a 2.5D hybrid model. The hybrid model describes the kinetics of the ions, while the electrons are modeled as massless neutralizing fluid in an expanding box approach. Turbulent magnetic fluctuations dominated by power-law frequency spectra, which are evident from in-situ as well as remote sensing measurements, are used in our models. The effects of background density inhomogeneity across the magnetic field on the resonant ion heating are studied. The effect of super-Alfvénic ion drift on the ion heating is investigated. It is found that the turbulent wave spectrum of initially parallel propagating waves cascades to oblique modes, and leads to enhanced resonant ion heating due to the inhomogeneity. The acceleration of the solar wind ions is achieved by the parametric instability of large amplitude waves in the spectrum, and is also affected by the inhomogeneity. The results of the study provide the ion temperature anisotropy and drift velocity temporal evolution due to relaxation of the instability. The non-Maxwellian velocity distribution functions (VDFs) of the ions are modeled in the inhomogeneous solar wind plasma in the acceleration region close to the Sun.

Characteristics of four SPE groups with different origins and acceleration processes

Science.gov (United States)

Kim, R.-S.; Cho, K.-S.; Lee, J.; Bong, S.-C.; Joshi, A. D.; Park, Y.-D.

2015-09-01

Solar proton events (SPEs) can be categorized into four groups based on their associations with flare or CME inferred from onset timings as well as acceleration patterns using multienergy observations. In this study, we have investigated whether there are any typical characteristics of associated events and acceleration sites in each group using 42 SPEs from 1997 to 2012. We find the following: (i) if the proton acceleration starts from a lower energy, a SPE has a higher chance to be a strong event (> 5000 particle flux per unit (pfu)) even if its associated flare and/or CME are not so strong. The only difference between the SPEs associated with flare and CME is the location of the acceleration site. (ii) For the former (Group A), the sites are very low (˜ 1 Rs) and close to the western limb, while the latter (Group C) have relatively higher (mean = 6.05 Rs) and wider acceleration sites. (iii) When the proton acceleration starts from the higher energy (Group B), a SPE tends to be a relatively weak event (pfu), although its associated CME is relatively stronger than previous groups. (iv) The SPEs categorized by the simultaneous acceleration in whole energy range within 10 min (Group D) tend to show the weakest proton flux (mean = 327 pfu) in spite of strong associated eruptions. Based on those results, we suggest that the different characteristics of SPEs are mainly due to the different conditions of magnetic connectivity and particle density, which are changed with longitude and height as well as their origin.

An accelerating reference frame for electromagnetic waves in a rapidly growing plasma

International Nuclear Information System (INIS)

Yablonovitch, E.

1989-01-01

In 1974, Hawking showed that black holes can evaporate by the emission of low temperature thermal radiation, now named Hawking radiation. Shortly thereafter, a closely related effect called Unruh radiation became apparent. The author discusses how, according to Unruh and Davies, observers of the electromagnetic field in an accelerating reference frame should see thermal radiation at a temperature T: KT = h/2π a/c where a is the acceleration relative to an inertial frame, c is the speed of light and h and K are Planck's and Boltzmann's constant respectively. In a frame accelerating at g = 980 cm/sec 2 , equivalent to the acceleration experienced at the earth's surface, this thermal radiation is at a temperature of only 4 x 10 -20 degrees K. Therefore, physicists hoping to observe this radiation, have sought out systems being subjected to extreme acceleration

Semiconductor acceleration sensor

Science.gov (United States)

Ueyanagi, Katsumichi; Kobayashi, Mitsuo; Goto, Tomoaki

1996-09-01

This paper reports a practical semiconductor acceleration sensor especially suited for automotive air bag systems. The acceleration sensor includes four beams arranged in a swastika structure. Two piezoresistors are formed on each beam. These eight piezoresistors constitute a Wheatstone bridge. The swastika structure of the sensing elements, an upper glass plate and a lower glass plate exhibit the squeeze film effect which enhances air dumping, by which the constituent silicon is prevented from breakdown. The present acceleration sensor has the following features. The acceleration force component perpendicular to the sensing direction can be cancelled. The cross-axis sensitivity is less than 3 percent. And, the erroneous offset caused by the differences between the thermal expansion coefficients of the constituent materials can be canceled. The high aspect ratio configuration realized by plasma etching facilitates reducing the dimensions and improving the sensitivity of the acceleration sensor. The present acceleration sensor is 3.9 mm by 3.9 mm in area and 1.2 mm in thickness. The present acceleration sensor can measure from -50 to +50 G with sensitivity of 0.275 mV/G and with non-linearity of less than 1 percent. The acceleration sensor withstands shock of 3000 G.

Accelerator-based conversion (ABC) of weapons plutonium: Plant layout study and related design issues

International Nuclear Information System (INIS)

Cowell, B.S.; Fontana, M.H.; Krakowski, R.A.; Beard, C.A.; Buksa, J.J.; Davidson, J.W.; Sailor, W.C.; Williamson, M.A.

1995-01-01

In preparation for and in support of a detailed R and D Plan for the Accelerator-Based Conversion (ABC) of weapons plutonium, an ABC Plant Layout Study was conducted at the level of a pre-conceptual engineering design. The plant layout is based on an adaptation of the Molten-Salt Breeder Reactor (MSBR) detailed conceptual design that was completed in the early 1070s. Although the ABC Plant Layout Study included the Accelerator Equipment as an essential element, the engineering assessment focused primarily on the Target; Primary System (blanket and all systems containing plutonium-bearing fuel salt); the Heat-Removal System (secondary-coolant-salt and supercritical-steam systems); Chemical Processing; Operation and Maintenance; Containment and Safety; and Instrumentation and Control systems. Although constrained primarily to a reflection of an accelerator-driven (subcritical) variant of MSBR system, unique features and added flexibilities of the ABC suggest improved or alternative approaches to each of the above-listed subsystems; these, along with the key technical issues in need of resolution through a detailed R ampersand D plan for ABC are described on the bases of the ''strawman'' or ''point-of-departure'' plant layout that resulted from this study

Students' Moral Reasoning as Related to Cultural Background and Educational Experience.

Science.gov (United States)

Bar-Yam, Miriam; And Others

The relationship between moral development and cultural and educational background is examined. Approximately 120 Israeli youth representing different social classes, sex, religious affiliation, and educational experience were interviewed. The youth interviewed included urban middle and lower class students, Kibbutz-born, Youth Aliyah…

Large electrostatic accelerators

Energy Technology Data Exchange (ETDEWEB)

Jones, C.M.

1984-01-01

The increasing importance of energetic heavy ion beams in the study of atomic physics, nuclear physics, and materials science has partially or wholly motivated the construction of a new generation of large electrostatic accelerators designed to operate at terminal potentials of 20 MV or above. In this paper, the author briefly discusses the status of these new accelerators and also discusses several recent technological advances which may be expected to further improve their performance. The paper is divided into four parts: (1) a discussion of the motivation for the construction of large electrostatic accelerators, (2) a description and discussion of several large electrostatic accelerators which have been recently completed or are under construction, (3) a description of several recent innovations which may be expected to improve the performance of large electrostatic accelerators in the future, and (4) a description of an innovative new large electrostatic accelerator whose construction is scheduled to begin next year. Due to time and space constraints, discussion is restricted to consideration of only tandem accelerators.

Large electrostatic accelerators

International Nuclear Information System (INIS)

Jones, C.M.

1984-01-01

The increasing importance of energetic heavy ion beams in the study of atomic physics, nuclear physics, and materials science has partially or wholly motivated the construction of a new generation of large electrostatic accelerators designed to operate at terminal potentials of 20 MV or above. In this paper, the author briefly discusses the status of these new accelerators and also discusses several recent technological advances which may be expected to further improve their performance. The paper is divided into four parts: (1) a discussion of the motivation for the construction of large electrostatic accelerators, (2) a description and discussion of several large electrostatic accelerators which have been recently completed or are under construction, (3) a description of several recent innovations which may be expected to improve the performance of large electrostatic accelerators in the future, and (4) a description of an innovative new large electrostatic accelerator whose construction is scheduled to begin next year. Due to time and space constraints, discussion is restricted to consideration of only tandem accelerators

CD97-decay-accelerating factor interaction is not involved in leukocyte adhesion to endothelial cells

NARCIS (Netherlands)

Boulday, Gwénola; Hamann, Jörg; Soulillou, Jean-Paul; Charreau, Béatrice

2002-01-01

Background. Effective improvement in xenograft survival is achieved using transplants from transgenic pigs expressing human complement (C) regulatory proteins, including decay-accelerating factor (DAF), CD59, and CD46 on endothelial cells (ECs). The aim of this study was to investigate whether human

CERN Accelerator School: Registration open for Advanced Accelerator Physics course

CERN Multimedia

2015-01-01

Registration is now open for the CERN Accelerator School’s Advanced Accelerator Physics course to be held in Warsaw, Poland from 27 September to 9 October 2015.   The course will be of interest to physicists and engineers who wish to extend their knowledge of accelerator physics. The programme offers core lectures on accelerator physics in the mornings and a practical course with hands-on tuition in the afternoons.  Further information can be found at: http://cas.web.cern.ch/cas/Poland2015/Warsaw-advert.html http://indico.cern.ch/event/361988/

CERN Accelerator School: Registration open for Advanced Accelerator Physics course

CERN Multimedia

2015-01-01

Registration is now open for the CERN Accelerator School’s Advanced Accelerator Physics course to be held in Warsaw, Poland from 27 September to 9 October 2015.   The course will be of interest to physicists and engineers who wish to extend their knowledge of Accelerator Physics. The programme offers core lectures on accelerator physics in the mornings and a practical course with hands-on tuition in the afternoons.  Further information can be found at: http://cas.web.cern.ch/cas/Poland2015/Warsaw-advert.html http://indico.cern.ch/event/361988/

Heavy ion accelerators

International Nuclear Information System (INIS)

Schmelzer, C.

1974-01-01

This review of the present state of work on heavy-ion accelerators pays particular attention to the requirements for nuclear research. It is divided into the following sections: single-particle versus collective acceleration, heavy-ion accelerators, beam quality, and a status report on the UNILAC facility. Among the topics considered are the recycling cyclotron, linacs with superconducting resonators, and acceleration to the GeV/nucleon range. (8 figures, 2 tables) (U.S.)

Accelerators at school

Energy Technology Data Exchange (ETDEWEB)

Anon.

1986-06-15

Latest subject covered by the CERN Accelerator School was 'Applied Geodesy of Particle Accelerators', which attracted an impressive number of outside participants to CERN for a week in April. Since the forerunners of today's particle accelerators were demonstrated over 50 years ago, the positioning of accelerator components has progressed from the laboratory bench-top to tunnels tens of kilometres long. Despite this phenomenal growth in size, sub-millimetre accuracy is still required.

Acceleration theorems

International Nuclear Information System (INIS)

Palmer, R.

1994-06-01

Electromagnetic fields can be separated into near and far components. Near fields are extensions of static fields. They do not radiate, and they fall off more rapidly from a source than far fields. Near fields can accelerate particles, but the ratio of acceleration to source fields at a distance R, is always less than R/λ or 1, whichever is smaller. Far fields can be represented as sums of plane parallel, transversely polarized waves that travel at the velocity of light. A single such wave in a vacuum cannot give continuous acceleration, and it is shown that no sums of such waves can give net first order acceleration. This theorem is proven in three different ways; each method showing a different aspect of the situation

The Source Equivalence Acceleration Method

International Nuclear Information System (INIS)

Everson, Matthew S.; Forget, Benoit

2015-01-01

Highlights: • We present a new acceleration method, the Source Equivalence Acceleration Method. • SEAM forms an equivalent coarse group problem for any spatial method. • Equivalence is also formed across different spatial methods and angular quadratures. • Testing is conducted using OpenMOC and performance is compared with CMFD. • Results show that SEAM is preferable for very expensive transport calculations. - Abstract: Fine-group whole-core reactor analysis remains one of the long sought goals of the reactor physics community. Such a detailed analysis is typically too computationally expensive to be realized on anything except the largest of supercomputers. Recondensation using the Discrete Generalized Multigroup (DGM) method, though, offers a relatively cheap alternative to solving the fine group transport problem. DGM, however, suffered from inconsistencies when applied to high-order spatial methods. While an exact spatial recondensation method was developed and provided full spatial consistency with the fine group problem, this approach substantially increased memory requirements for realistic problems. The method described in this paper, called the Source Equivalence Acceleration Method (SEAM), forms a coarse-group problem which preserves the fine-group problem even when using higher order spatial methods. SEAM allows recondensation to converge to the fine-group solution with minimal memory requirements and little additional overhead. This method also provides for consistency when using different spatial methods and angular quadratures between the coarse group and fine group problems. SEAM was implemented in OpenMOC, a 2D MOC code developed at MIT, and its performance tested against Coarse Mesh Finite Difference (CMFD) acceleration on the C5G7 benchmark problem and on a 361 group version of the problem. For extremely expensive transport calculations, SEAM was able to outperform CMFD, resulting in speed-ups of 20–45 relative to the normal power

A new approach to modeling linear accelerator systems

International Nuclear Information System (INIS)

Gillespie, G.H.; Hill, B.W.; Jameson, R.A.

1994-01-01

A novel computer code is being developed to generate system level designs of radiofrequency ion accelerators with specific applications to machines of interest to Accelerator Driven Transmutation Technologies (ADTT). The goal of the Accelerator System Model (ASM) code is to create a modeling and analysis tool that is easy to use, automates many of the initial design calculations, supports trade studies used in accessing alternate designs and yet is flexible enough to incorporate new technology concepts as they emerge. Hardware engineering parameters and beam dynamics are to be modeled at comparable levels of fidelity. Existing scaling models of accelerator subsystems were used to produce a prototype of ASM (version 1.0) working within the Shell for Particle Accelerator Related Code (SPARC) graphical user interface. A small user group has been testing and evaluating the prototype for about a year. Several enhancements and improvements are now being developed. The current version of ASM is described and examples of the modeling and analysis capabilities are illustrated. The results of an example study, for an accelerator concept typical of ADTT applications, is presented and sample displays from the computer interface are shown

Cosmic ray acceleration mechanisms

International Nuclear Information System (INIS)

Cesarsky, C.J.

1982-09-01

We present a brief summary of some of the most popular theories of cosmic ray acceleration: Fermi acceleration, its application to acceleration by shocks in a scattering medium, and impulsive acceleration by relativistic shocks

Senegal: Background and U.S. Relations

Science.gov (United States)

2011-03-25

treatment of prisoners; corruption; violence and discrimination against women; child abuse, child labor, and child marriage ; and human trafficking...and U.S. Relations Congressional Research Service 8 both are reportedly widespread.36 Senegalese law also criminalizes homosexuality , and...Senegalese legislature amended the constitution and passed legislation aimed at removing any legal obstacles. However, the government has since stalled

Accelerator research studies: Progress report, Task B

International Nuclear Information System (INIS)

1985-06-01

The main objectives in Task B of the research program are summarized as follows: (1) studies of the collective acceleration of positive ions from a localized plasma source by an intense relativistic electron beam (IREB), (2) studies of ways in which external control may be achieved over the electron beam front in order to achieve higher ion energies - the Beam Front Accelerator (BFA) concept, and (3) study of electron and ion beam generation in a new kind of compact pulsed accelerator in which energy is stored inductively and switched using a plasma focus opening switch. During the past year, substantial progress was made in each of these areas. Our exploratory research on the collective acceleration of laser-produced ions has confirmed the acceleration of C, Al, and Fe ions to peak energies in excess of 10 MeV/amu. In addition, studies of the relation between collective ion acceleration and electron beam propagation in vacuum have shed new light on the experimental processes that lead to energy transfer from electrons to ions. Meanwhile, extensive progress has been made in our attempts to use analytical theory and numerical simulation to model ion acceleration in these systems. Our resultant improved understanding of the processes that limit the peak ion energy has had a profound impact on our plans for further research in this area. Studies of the Compact Pulsed Accelerator have included both ion and electron beam extraction from the device. Its potential to reduce the volume of pulse power sources by an order of magnitude has already been demonstrated, and plans are currently underway to scale the experiment up to voltages in the 1 MV range

FERMILAB ACCELERATOR R&D PROGRAM TOWARDS INTENSITY FRONTIER ACCELERATORS : STATUS AND PROGRESS

Energy Technology Data Exchange (ETDEWEB)

Shiltsev, Vladimir [Fermilab

2016-11-15

The 2014 P5 report indicated the accelerator-based neutrino and rare decay physics research as a centrepiece of the US domestic HEP program at Fermilab. Operation, upgrade and development of the accelerators for the near- term and longer-term particle physics program at the Intensity Frontier face formidable challenges. Here we discuss key elements of the accelerator physics and technology R&D program toward future multi-MW proton accelerators and present its status and progress. INTENSITY FRONTIER ACCELERATORS

Recircular accelerator to proton ocular therapy

International Nuclear Information System (INIS)

Rabelo, Luisa A.; Campos, Tarcisio P.R.

2013-01-01

Proton therapy has been used for the treatment of Ocular Tumors, showing control in most cases as well as conservation of the eyeball, avoiding the enucleation. The protons provide higher energetic deposition in depth with reduced lateral spread, compared to the beam of photons and electrons, with characteristic dose deposition peak (Bragg peak). This technique requires large particle accelerators hampering the deployment a Proton Therapy Center in some countries due to the need for an investment of millions of dollars. This study is related to a new project of an electromagnetic unit of proton circular accelerator to be coupled to the national radiopharmaceutical production cyclotrons, to attend ocular therapy. This project evaluated physical parameters of proton beam circulating through classical and relativistic mechanical formulations and simulations based on an ion transport code in electromagnetic fields namely CST (Computer Simulation Technology). The structure is differentiated from other circular accelerations (patent CTIT/UFMG NRI research group/UFMG). The results show the feasibility of developing compact proton therapy equipment that works like pre-accelerator or post-accelerator to cyclotrons, satisfying the interval energy of 15 MeV to 64 MeV. Methods of reducing costs of manufacture, installation and operation of this equipment will facilitate the dissemination of the proton treatment in Brazil and consequently advances in fighting cancer. (author)

Recircular accelerator to proton ocular therapy

Energy Technology Data Exchange (ETDEWEB)

Rabelo, Luisa A.; Campos, Tarcisio P.R., E-mail: luisarabelo88@gmail.com, E-mail: tprcampos@pq.cnpq.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear

2013-07-01

Proton therapy has been used for the treatment of Ocular Tumors, showing control in most cases as well as conservation of the eyeball, avoiding the enucleation. The protons provide higher energetic deposition in depth with reduced lateral spread, compared to the beam of photons and electrons, with characteristic dose deposition peak (Bragg peak). This technique requires large particle accelerators hampering the deployment a Proton Therapy Center in some countries due to the need for an investment of millions of dollars. This study is related to a new project of an electromagnetic unit of proton circular accelerator to be coupled to the national radiopharmaceutical production cyclotrons, to attend ocular therapy. This project evaluated physical parameters of proton beam circulating through classical and relativistic mechanical formulations and simulations based on an ion transport code in electromagnetic fields namely CST (Computer Simulation Technology). The structure is differentiated from other circular accelerations (patent CTIT/UFMG NRI research group/UFMG). The results show the feasibility of developing compact proton therapy equipment that works like pre-accelerator or post-accelerator to cyclotrons, satisfying the interval energy of 15 MeV to 64 MeV. Methods of reducing costs of manufacture, installation and operation of this equipment will facilitate the dissemination of the proton treatment in Brazil and consequently advances in fighting cancer. (author)

Safety in design and operation of low energy particle accelerators

International Nuclear Information System (INIS)

Badawy, I.

1991-01-01

This paper studies the safety in design and operation of low energy accelerators which produce beams of accelerated charged particles and radiations. As radiation sources, the accelerators are widely used in scientific research, industry, food and medical applications. The risks to human and environment are considered. The safety in accelerators is discussed-particularly-the shielding against ionizing radiations, overexposure to RF radiation fire hazards and power failures. Also the paper studies the emergency response at incidents. Emergency procedures are recommended for each type of emergency. Reporting to the competent Authority is also recommended to be prepared for each incident. The basic principles of regulatory control, licensing and inspections for accelerator facilities are discussed. The relation with the competent authority is pointed out. 4 fig

Accelerators at school

International Nuclear Information System (INIS)

Anon.

1986-01-01

Latest subject covered by the CERN Accelerator School was 'Applied Geodesy of Particle Accelerators', which attracted an impressive number of outside participants to CERN for a week in April. Since the forerunners of today's particle accelerators were demonstrated over 50 years ago, the positioning of accelerator components has progressed from the laboratory bench-top to tunnels tens of kilometres long. Despite this phenomenal growth in size, sub-millimetre accuracy is still required

Particle beam accelerator

International Nuclear Information System (INIS)

Turner, N.L.

1982-01-01

A particle beam accelerator is described which has several electrodes that are selectively short circuited together synchronously with changes in the magnitude of a DC voltage applied to the accelerator. By this method a substantially constant voltage gradient is maintained along the length of the unshortened electrodes despite variations in the energy applied to the beam by the accelerator. The invention has particular application to accelerating ion beams that are implanted into semiconductor wafers. (U.K.)

Large electrostatic accelerators

International Nuclear Information System (INIS)

Jones, C.M.

1984-01-01

The paper is divided into four parts: a discussion of the motivation for the construction of large electrostatic accelerators, a description and discussion of several large electrostatic accelerators which have been recently completed or are under construction, a description of several recent innovations which may be expected to improve the performance of large electrostatic accelerators in the future, and a description of an innovative new large electrostatic accelerator whose construction is scheduled to begin next year

An introduction to acceleration mechanisms

International Nuclear Information System (INIS)

Palmer, R.B.

1987-05-01

This paper discusses the acceleration of charged particles by electromagnetic fields, i.e., by fields that are produced by the motion of other charged particles driven by some power source. The mechanisms that are discussed include: Ponderamotive Forces, Acceleration, Plasma Beat Wave Acceleration, Inverse Free Electron Laser Acceleration, Inverse Cerenkov Acceleration, Gravity Acceleration, 2D Linac Acceleration and Conventional Iris Loaded Linac Structure Acceleration

Acceleration in the care of older adults: new demands as predictors of employee burnout and engagement.

Science.gov (United States)

Kubicek, Bettina; Korunka, Christian; Ulferts, Heike

2013-07-01

This paper introduces the concept of acceleration-related demands in the care of older adults. It examines these new demands and their relation to cognitive, emotional, and physical job demands and to employee well-being. Various changes in the healthcare systems of Western societies pose new demands for healthcare professionals' careers and jobs. In particular today's societal changes give rise to acceleration-related demands, which manifest themselves in work intensification and in increasing requirements to handle new technical equipment and to update one's job-related knowledge. It is, therefore, of interest to investigate the effects of these new demands on the well-being of employees. Survey. Between March-June 2010 the survey was conducted among healthcare professionals involved in care of older adults in Austria. A total of 1498 employees provided data on cognitive, emotional, and physical job demands and on acceleration-related demands. The outcome variables were the core dimensions of burnout (emotional exhaustion and depersonalization) and engagement (vigour and dedication). Hierarchical regression analyses show that acceleration-related demands explain additional variance for exhaustion, depersonalization, vigour, and dedication when controlling for cognitive, emotional, and physical demands. Furthermore, acceleration-related demands associated with increasing requirements to update one's knowledge are related to positive outcomes (vigour and dedication). Acceleration-related demands associated with an increasing work pace are related to negative outcomes such as emotional exhaustion. Results illustrate that new demands resulting from social acceleration generate potential challenges for on-the-job learning and potential risks to employees' health and well-being. © 2012 Blackwell Publishing Ltd.

CAS CERN Accelerator School second advanced accelerator physics course

International Nuclear Information System (INIS)

Turner, S.

1989-01-01

The advanced course on general accelerator physics given in West Berlin closely followed that organised by the CERN Accelerator School at Oxford in September 1985 and whose proceedings were published as CERN Yellow Report 87-03 (1987). However, certain subjects were treated in a different way, improved or extended, while some new ones were introduced and it is all of these which are included in the present proceedings. The lectures include particle-photon interactions, high-brilliance lattices and single/multiple Touschek effect, while the seminars are on the major accelerators presently under construction or proposed for the near future, applications of synchrotron radiation, free-electron lasers, cosmic accelerators and crystal beams. Also included are errata, and addenda to some of the lectures, of CERN 87-03. (orig.)

2014 CERN Accelerator Schools: Beam Loss and Accelerator Protection

CERN Multimedia

2014-01-01

The US-CERN-JAPAN-RUSSIA Joint International Accelerator School is organising a course on Beam Loss and Accelerator Protection to be held in Newport Beach, California, USA from 5-14 November, 2014.    This school is intended for physicists and engineers who are or may be engaged in the design, construction, and/or operation of accelerators with high power photon or particle beams and/or accelerator sub-systems with large stored energy. Application deadlines are 15 August and 4 September. Further information on this Joint School can be found at: http://cas.web.cern.ch/cas/JAS/Newport%20Beach%202014/NPBadvert.html http://indico.cern.ch/event/287647/ http://uspas.fnal.gov/programs/JAS/JAS14.shtml

Vp x B acceleration

International Nuclear Information System (INIS)

Sugihara, Ryo.

1987-05-01

A unique particle acceleration by an electrostatic (ES) wave, a magnetosonic shock wave as well as an electromagnetic (EM) wave is reviewed. The principle of the acceleration is that when a charged particle is carried across an external magnetic field the charge feels a DC field (the Lorentz force) and is accelerated. The theory for the ES wave acceleration is experimentally verified thought it is semi-quantitative. The shock acceleration is extensively studied theoretically and in a particle simulation method and the application is extended to phenomena in interplanetary space. The EM wave acceleration is based on a trapping in a moving neutral sheet created by the wave magnetic field and the external magnetic field, and the particle can be accelerated indefinitely. A brief sketch on a slow-wave-structure for this acceleration will be given. (author)

Acceleration of polarized proton in high energy accelerators

International Nuclear Information System (INIS)

Lee, S.Y.

1991-01-01

In low to medium energy accelerators, betatron tune jumps and vertical orbit harmonic correction methods have been used to overcome the intrinsic and imperfection resonances. At high energy accelerators, snakes are needed to preserve polarization. The author analyzes the effects of snake resonances, snake imperfections, and overlapping resonances on spin depolarization. He discusses also results of recent snake experiments at the IUCF Cooler Ring. The snake can overcome various kinds of spin depolarization resonances. These experiments pointed out further that partial snake can be used to cure the imperfection resonances in low to medium energy accelerators

Simulation studies of acceleration of heavy ions and their elemental compositions

International Nuclear Information System (INIS)

Toida, Mieko; Ohsawa, Yukiharu

1996-07-01

By using a one-dimensional, electromagnetic particle simulation code with full ion and electron dynamics, we have studied the acceleration of heavy ions by a nonlinear magnetosonic wave in a multi-ion-species plasma. First, we describe the mechanism of heavy ion acceleration by magnetosonic waves. We then investigate this by particle simulations. The simulation plasma contains four ion species: H, He, O, and Fe. The number density of He is taken to be 10% of that of H, and those of O and Fe are much lower. Simulations confirm that, as in a single-ion-species plasma, some of the hydrogens can be accelerated by the longitudinal electric field formed in the wave. Furthermore, they show that magnetosonic waves can accelerate all the particles of all the heavy species (He, O, and Fe) by a different mechanism, i.e., by the transverse electric field. The maximum speeds of the heavy species are about the same, of the order of the wave propagation speed. These are in good agreement with theoretical prediction. These results indicate that, if high-energy ions are produced in the solar corona through these mechanisms, the elemental compositions of these heavy ions can be similar to that of the background plasma, i.e., the corona

Supersonic micro-jets and their application to few-cycle laser-driven electron acceleration

International Nuclear Information System (INIS)

Schmid, Karl

2009-01-01

This thesis covers the few-cycle laser-driven acceleration of electrons in a laser-generated plasma. The laser system employed in this work is a new development based on optical parametric chirped pulse amplification and is the only multi-TW few-cycle laser in the world. In the experiment, the laser beam is focused onto a supersonic helium gas jet which leads to the formation of a plasma channel. The laser pulse, having an intensity of 10 19 W/cm 2 propagates through the plasma with an electron density of 2 x 10 19 cm -3 and forms via a highly nonlinear interaction a strongly anharmonic plasma wave. The amplitude of the wave is so large that the wave breaks, thereby injecting electrons from the background plasma into the accelerating phase. The energy transfer from the laser pulse to the plasma is so strong that the maximum propagation distance is limited to the 100 m range. Therefore, gas jets specifically tuned to these requirements have to be employed. The properties of microscopic supersonic gas jets are thoroughly analyzed in this work. Based on numeric flow simulation, this study encompasses several extensive parameter studies that illuminate all relevant features of supersonic flows in microscopic gas nozzles. This allowed the optimized design of de Laval nozzles with exit diameters ranging from 150 μm to 3 mm. The employment of these nozzles in the experiment greatly improved the electron beam quality. After these optimizations, the laser-driven electron accelerator now yields monoenergetic electron pulses with energies up to 50 MeV and charges between one and ten pC. The electron beam has a typical divergence of 5 mrad and comprises an energy spectrum that is virtually free from low energetic background. The electron pulse duration could not yet be determined experimentally but simulations point towards values in the range of 1 fs. The acceleration gradient is estimated from simulation and experiment to be approximately 0.5 TV/m. The electron accelerator

Supersonic micro-jets and their application to few-cycle laser-driven electron acceleration

Energy Technology Data Exchange (ETDEWEB)

Schmid, Karl

2009-07-23

This thesis covers the few-cycle laser-driven acceleration of electrons in a laser-generated plasma. The laser system employed in this work is a new development based on optical parametric chirped pulse amplification and is the only multi-TW few-cycle laser in the world. In the experiment, the laser beam is focused onto a supersonic helium gas jet which leads to the formation of a plasma channel. The laser pulse, having an intensity of 10{sup 19} W/cm{sup 2} propagates through the plasma with an electron density of 2 x 10{sup 19} cm{sup -3} and forms via a highly nonlinear interaction a strongly anharmonic plasma wave. The amplitude of the wave is so large that the wave breaks, thereby injecting electrons from the background plasma into the accelerating phase. The energy transfer from the laser pulse to the plasma is so strong that the maximum propagation distance is limited to the 100 m range. Therefore, gas jets specifically tuned to these requirements have to be employed. The properties of microscopic supersonic gas jets are thoroughly analyzed in this work. Based on numeric flow simulation, this study encompasses several extensive parameter studies that illuminate all relevant features of supersonic flows in microscopic gas nozzles. This allowed the optimized design of de Laval nozzles with exit diameters ranging from 150 {mu}m to 3 mm. The employment of these nozzles in the experiment greatly improved the electron beam quality. After these optimizations, the laser-driven electron accelerator now yields monoenergetic electron pulses with energies up to 50 MeV and charges between one and ten pC. The electron beam has a typical divergence of 5 mrad and comprises an energy spectrum that is virtually free from low energetic background. The electron pulse duration could not yet be determined experimentally but simulations point towards values in the range of 1 fs. The acceleration gradient is estimated from simulation and experiment to be approximately 0.5 TV/m. The

Collective ion acceleration

International Nuclear Information System (INIS)

Godfrey, B.B.; Faehl, R.J.; Newberger, B.S.; Shanahan, W.R.; Thode, L.E.

1977-01-01

Progress achieved in the understanding and development of collective ion acceleration is presented. Extensive analytic and computational studies of slow cyclotron wave growth on an electron beam in a helix amplifier were performed. Research included precise determination of linear coupling between beam and helix, suppression of undesired transients and end effects, and two-dimensional simulations of wave growth in physically realizable systems. Electrostatic well depths produced exceed requirements for the Autoresonant Ion Acceleration feasibility experiment. Acceleration of test ions to modest energies in the troughs of such waves was also demonstrated. Smaller efforts were devoted to alternative acceleration mechanisms. Langmuir wave phase velocity in Converging Guide Acceleration was calculated as a function of the ratio of electron beam current to space-charge limiting current. A new collective acceleration approach, in which cyclotron wave phase velocity is varied by modulation of electron beam voltage, is proposed. Acceleration by traveling Virtual Cathode or Localized Pinch was considered, but appears less promising. In support of this research, fundamental investigations of beam propagation in evacuated waveguides, of nonneutral beam linear eigenmodes, and of beam stability were carried out. Several computer programs were developed or enhanced. Plans for future work are discussed

Accelerators for Medicine

CERN Multimedia

CERN. Geneva

2018-01-01

This lecture will review the different applications of particle accelerators to the medical field, from cancer treatment with beams of accelerator-produced particles (photons, electrons, protons, ions and neutrons) to the generation of radioactive isotopes used in medical diagnostics, in cancer therapy and in the new domain of theragnostics. For each application will be outlined the state of the art, the potential, and the accelerator challenges to be faced to meet the increasing demand for therapeutic procedures based on accelerators.

Commissioning and Acceptance Testing of the existing linear accelerator upgraded to volumetric modulated arc therapy

Science.gov (United States)

Varadharajan, Ekambaram; Ramasubramanian, Velayudham

2013-01-01

Aim The RapidArc commissioning and Acceptance Testing program will test and ensure accuracy in DMLC position, precise dose-rate control during gantry rotation and accurate control of gantry speed. Background Recently, we have upgraded our linear accelerator capable of performing IMRT which was functional from 2007 with image guided RapidArc facility. The installation of VMAT in the existing linear accelerator is a tedious process which requires many quality assurance procedures before the proper commissioning of the facility and these procedures are discussed in this study. Materials and methods Output of the machine at different dose rates was measured to verify its consistency at different dose rates. Monitor and chamber linearity at different dose rates were checked. DMLC QA comprising of MLC transmission factor measurement and dosimetric leaf gap measurements were performed using 0.13 cm3 and 0.65 cm3 Farmer type ionization chamber, dose 1 dosimeter, and IAEA 30 cm × 30 cm × 30 cm water phantom. Picket fence test, garden fence test, tests to check leaf positioning accuracy due to carriage movement, calibration of the leaves, leaf speed stability effects due to the acceleration and deceleration of leaves, accuracy and calibration of leaves in producing complex fields, effects of interleaf friction, etc. were verified using EDR2 therapy films, Vidar scanner, Omnipro accept software, amorphous silicon based electronic portal imaging device and EPIQA software.1–8 Results All the DMLC related quality assurance tests were performed and evaluated by film dosimetry, portal dosimetry and EPIQA.7 Conclusion Results confirmed that the linear accelerator is capable of performing accurate VMAT. PMID:24416566

Status report of pelletron accelerator and ECR based heavy ion accelerator programme

International Nuclear Information System (INIS)

Gupta, A.K.

2015-01-01

The BARC-TIFR Pelletron Accelerator is completing twenty seven years of round-the-clock operation, serving diverse users from institutions within and outside DAE. Over the years, various developmental activities and application oriented programs have been initiated at Pelletron Accelerator Facility, resulting into enhanced utilization of the accelerator. We have also been pursuing an ECR based heavy ion accelerator programme under XII th Plan, consisting of an 18 GHz superconducting ECR (Electron Cyclotron Resonance) ion source and a room temperature RFQ (Radio Frequency Quadrupole) followed by low and high beta superconducting niobium resonator cavities. This talk will provide the current status of Pelletron Accelerator and the progress made towards the ECR based heavy ion accelerator program at BARC. (author)

Acceleration parameters for fluid physics with accelerating bodies

CSIR Research Space (South Africa)

Gledhill, Irvy MA

2016-06-01

Full Text Available to an acceleration parameter that appears to be new in fluid physics, but is known in cosmology. A selection of cases for rectilinear acceleration has been chosen to illustrate the point that this parameter alone does not govern regimes of flow about significantly...

Impulsive ion acceleration in earth's outer magnetosphere

International Nuclear Information System (INIS)

Baker, D.N.; Belian, R.D.

1985-01-01

Considerable observational evidence is found that ions are accelerated to high energies in the outer magnetosphere during geomagnetic disturbances. The acceleration often appears to be quite impulsive causing temporally brief (10's of seconds), very intense bursts of ions in the distant plasma sheet as well as in the near-tail region. These ion bursts extend in energy from 10's of keV to over 1 MeV and are closely associated with substorm expansive phase onsets. Although the very energetic ions are not of dominant importance for magnetotail plasma dynamics, they serve as an important tracer population. Their absolute intensity and brief temporal appearance bespeaks a strong and rapid acceleration process in the near-tail, very probably involving large induced electric fields substantially greater than those associated with cross-tail potential drops. Subsequent to their impulsive acceleration, these ions are injected into the outer trapping regions forming ion ''drift echo'' events, as well as streaming tailward away from their acceleration site in the near-earth plasma sheet. Most auroral ion acceleration processes occur (or are greatly enhanced) during the time that these global magnetospheric events are occurring in the magnetotail. A qualitative model relating energetic ion populations to near-tail magnetic reconnection at substorm onset followed by global redistribution is quite successful in explaining the primary observational features. Recent measurements of the elemental composition and charge-states have proven valuable for showing the source (solar wind or ionosphere) of the original plasma population from which the ions were accelerated

Accessing Intel FPGAs for Acceleration

CERN Multimedia

CERN. Geneva

2018-01-01

In this presentation, we will discuss the latest tools and products from Intel that enables FPGAs to be deployed as Accelerators. We will first talk about the Acceleration Stack for Intel Xeon CPU with FPGAs which makes it easy to create, verify, and execute functions on the Intel Programmable Acceleration Card in a Data Center. We will then talk about the OpenCL flow which allows parallel software developers to create FPGA systems and deploy them using the OpenCL standard. Next, we will talk about the Intel High-Level Synthesis compiler which can convert C++ code into custom RTL code optimized for Intel FPGAs. Lastly, we will focus on the task of running Machine Learning inference on the FPGA leveraging some of the tools we discussed. About the speaker Karl Qi is Sr. Staff Applications Engineer, Technical Training. He has been with the Customer Training department at Altera/Intel for 8 years. Most recently, he is responsible for all training content relating to High-Level Design tools, including the OpenCL...

Accelerator-driven X-ray Sources

Energy Technology Data Exchange (ETDEWEB)

Nguyen, Dinh Cong [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2015-11-09

After an introduction which mentions x-ray tubes and storage rings and gives a brief review of special relativity, the subject is treated under the following topics and subtopics: synchrotron radiation (bending magnet radiation, wiggler radiation, undulator radiation, brightness and brilliance definition, synchrotron radiation facilities), x-ray free-electron lasers (linac-driven X-ray FEL, FEL interactions, self-amplified spontaneous emission (SASE), SASE self-seeding, fourth-generation light source facilities), and other X-ray sources (energy recovery linacs, Inverse Compton scattering, laser wakefield accelerator driven X-ray sources. In summary, accelerator-based light sources cover the entire electromagnetic spectrum. Synchrotron radiation (bending magnet, wiggler and undulator radiation) has unique properties that can be tailored to the users’ needs: bending magnet and wiggler radiation is broadband, undulator radiation has narrow spectral lines. X-ray FELs are the brightest coherent X-ray sources with high photon flux, femtosecond pulses, full transverse coherence, partial temporal coherence (SASE), and narrow spectral lines with seeding techniques. New developments in electron accelerators and radiation production can potentially lead to more compact sources of coherent X-rays.

In-beam background suppression shield

DEFF Research Database (Denmark)

Santoro, V.; Cai, Xiao Xiao; DiJulio, D. D.

2015-01-01

The long (3 ms) proton pulse of the European Spallation Source (ESS) gives rise to unique and potentially high backgrounds for the instrument suite. In such a source an instrument's capabilities will be limited by its Signal to Noise (S/N) ratio. The instruments with a direct view of the moderator......, which do not use a bender to help mitigate the fast neutron background, are the most challenging. For these beam lines we propose the innovative shielding of placing blocks of material directly into the guide system, which allow a minimum attenuation of the cold and thermal fluxes relative...... to the background suppression. This shielding configuration has been worked into a beam line model using Geant4. We study particularly the advantages of single crystal sapphire and silicon blocks....

Illinois Accelerator Research Center

Science.gov (United States)

Kroc, Thomas K.; Cooper, Charlie A.

The Illinois Accelerator Research Center (IARC) hosts a new accelerator development program at Fermi National Accelerator Laboratory. IARC provides access to Fermi's state-of-the-art facilities and technologies for research, development and industrialization of particle accelerator technology. In addition to facilitating access to available existing Fermi infrastructure, the IARC Campus has a dedicated 36,000 ft2 Heavy Assembly Building (HAB) with all the infrastructure needed to develop, commission and operate new accelerators. Connected to the HAB is a 47,000 ft2 Office, Technology and Engineering (OTE) building, paid for by the state, that has office, meeting, and light technical space. The OTE building, which contains the Accelerator Physics Center, and nearby Accelerator and Technical divisions provide IARC collaborators with unique access to world class expertise in a wide array of accelerator technologies. At IARC scientists and engineers from Fermilab and academia work side by side with industrial partners to develop breakthroughs in accelerator science and translate them into applications for the nation's health, wealth and security.

FFAGS for muon acceleration

International Nuclear Information System (INIS)

Berg, J. Scott; Kahn, Stephen; Palmer, Robert; Trbojevic, Dejan; Johnstone, Carol; Keil, Eberhard; Aiba, Masamitsu; Machida, Shinji; Mori, Yoshiharu; Ogitsu, Toru; Ohmori, Chihiro; Sessler, Andrew; Koscielniak, Shane

2003-01-01

Due to their finite lifetime, muons must be accelerated very rapidly. It is challenging to make the magnets ramp fast enough to accelerate in a synchrotron, and accelerating in a linac is very expensive. One can use a recirculating accelerator (like CEBAF), but one needs a different arc for each turn, and this limits the number of turns one can use to accelerate, and therefore requires significant amounts of RF to achieve the desired energy gain. An alternative method for muon acceleration is using a fixed field alternating gradient (FFAG) accelerator. Such an accelerator has a very large energy acceptance (a factor of two or three), allowing one to use the same arc with a magnetic field that is constant over time. Thus, one can in principle make as many turns as one can tolerate due to muon decay, therefore reducing the RF cost without increasing the arc cost. This paper reviews the current status of research into the design of FFAGs for muon acceleration. Several current designs are described and compared. General design considerations are also discussed

Research of accelerator-based neutron source for boron neutron capture therapy

International Nuclear Information System (INIS)

Li Changkai; Ma Yingjie; Tang Xiaobin; Xie Qin; Geng Changran; Chen Da

2013-01-01

Background: 7 Li (p, n) reaction of high neutron yield and low threshold energy has become one of the most important neutron generating reactions for Accelerator-based Boron Neutron Capture Therapy (BNCT). Purpose Focuses on neutron yield and spectrum characteristics of this kind of neutron generating reaction which serves as an accelerator-based neutron source and moderates the high energy neutron beams to meet BNCT requirements. Methods: The yield and energy spectrum of neutrons generated by accelerator-based 7 Li(p, n) reaction with incident proton energy from 1.9 MeV to 3.0 MeV are researched using the Monte Carlo code-MCNPX2.5.0. And the energy and angular distribution of differential neutron yield by 2.5-MeV incident proton are also given in this part. In the following part, the character of epithermal neutron beam generated by 2.5-MeV incident protons is moderated by a new-designed moderator. Results: Energy spectra of neutrons generated by accelerator-based 7 Li(p, n) reaction with incident proton energy from 1.9 MeV to 3.0 MeV are got through the simulation and calculation. The best moderator thickness is got through comparison. Conclusions: Neutron beam produced by accelerator-based 7 Li(p, n) reaction, with the bombarding beam of 10 mA and the energy of 2.5 MeV, can meet the requirement of BNCT well after being moderated. (authors)

Progress Towards a Laboratory Test of Alfvénic Electron Acceleration

Science.gov (United States)

Schroeder, J. W. R.; Skiff, F.; Howes, G. G.; Kletzing, C. A.; Carter, T. A.; Vincena, S.; Dorfman, S.

2016-10-01

Alfvén waves are thought to be a key mechanism for accelerating auroral electrons. Due to inherent limitations of single point measurements, in situ data has been unable to demonstrate a causal relationship between Alfvén waves and accelerated electrons. Electron acceleration occurs in the inner magnetosphere where the Alfvén speed is greater than the electron thermal speed. In these conditions, Alfvén waves can have an electric field aligned with the background magnetic field B0 if the scale of wave structure across B0 is comparable to the electron skin depth. In the Large Plasma Device (LaPD), Alfvén waves are launched in conditions relevant to the inner magnetosphere. The reduced parallel electron distribution function is measured using a whistler-mode wave absorption diagnostic. The linear electron response has been measured as oscillations of the electron distribution function at the Alfvén wave frequency. These measurements agree with linear theory. Current efforts focus on measuring the nonlinear acceleration of electrons that is relevant to auroral generation. We report on recent progress including experiments with a new higher-power Alfvén wave antenna with the goal of measuring nonlinear electron acceleration. This work was supported by the NSF GRFP and by Grants from NSF, DOE, and NASA. Experiments were performed at the Basic Plasma Science Facility which is funded by DOE and NSF.

Susceptibility of materials processing experiments to low-level accelerations

Science.gov (United States)

Naumann, R. J.

1981-01-01

The types of material processing experiments being considered for shuttle can be grouped into four categories: (1) contained solidification experiment; (2) quasicontainerless experiments; (3) containerless experiments; and (4) fluids experiments. Low level steady acceleration, compensated and uncompensated transient accelerations, and rotation induced flow factors that must be considered in the acceleration environment of a space vehicle whose importance depends on the type of experiment being performed. Some control of these factors may be exercised by the location and orientation of the experiment relative to shuttle and by the orbit vehicle attitude chosen for mission. The effects of the various residual accelerations can have serious consequence to the control of the experiment and must be factored into the design and operation of the apparatus.

Performance of the intense pulsed neutron source accelerator system

International Nuclear Information System (INIS)

Potts, C.; Brumwell, F.; Rauchas, A.; Stipp, V.; Volk, G.

1983-01-01

The Intense Pulsed Neutron Source (IPNS) facility has now been operating in a routine way for outside users since November 1, 1981. From that date through December of 1982, the accelerator system was scheduled for neutron science for 4500 hours. During this time the accelerator achieved its short-term goals by delivering about 380,000,000 pulses of beam totaling over 6 x 10 20 protons. The changes in equipment and operating practices that evolved during this period of intense running are described. The intensity related instability threshold was increased by a factor of two and the accelerator beam current has been ion source limited. Plans to increase the accelerator intensity are also described. Initial operating results with a new H - ion source are discussed

NLC. A test accelerator for the next linear collider

International Nuclear Information System (INIS)

Ruth, R.D.; Adolphsen, C.; Bane, K.; Boyce, R.F.; Burke, D.L.; Callin, R.; Caryotakis, G.; Cassel, R.; Clark, S.L.; Deruyter, H.; Fant, K.; Fuller, R.; Heifets, S.; Hoag, H.; Humphrey, R.; Kheifets, S.; Koontz, R.; Kroll, N.M.; Lavine, T.; Loew, G.A.; Menegat, A.; Miller, R.H.; Nantista, C.; Paterson, J.M.; Pearson, C.; Phillips, R.; Rifkin, J.; Spencer, J.; Tantawi, S.; Thompson, K.A.; Vlieks, A.; Vylet, V.; Wang, J.W.; Wilson, P.B.; Yeremian, A.; Youngman, B.

1993-01-01

At SLAC, we are pursuing the design of a Next Linear Collider (NLC) which would begin with a center-of-mass energy of 0.5 TeV, and be upgradable to at least 1.0 TeV. To achieve this high energy, we have been working on the development of a high-gradient 11.4-GHz (X-band) linear accelerator for the main linac of the collider. In this paper, we present the design of a 'Next Linear Collider Test Accelerator' (NLCTA). The goal of the NLCTA is to incorporate the new technologies of X-band accelerator structures, RF pulse compression systems and klystrons into a short linac which will then be a test bed for beam dynamics issues related to high-gradient acceleration. (orig.)

The electron accelerator Ridgetron

International Nuclear Information System (INIS)

Hayashizaki, N.; Hattori, T.; Odera, M.; Fujisawa, T.

1999-01-01

Many electron accelerators of DC or RF type have been widely used for electron beam irradiation (curing, crosslinking of polymers, sterilization of medical disposables, preservation of food, etc.). Regardless of the acceleration energy, the accelerators to be installed in industrial facilities, have to satisfy the requires of compact size, low power consumption and stable operation. The DC accelerator is realized very compact in the energy under 300 keV, however, it is large to prevent the discharge of an acceleration column in the energy over 300 keV. The RF electron accelerator Ridgetron has been developed to accelerate the continuous beam of the 0.5-10 MeV range in compact space. It is the first example as an electron accelerator incorporated a ridged RF cavity. A prototype system of final energy of 2.5 MeV has been studied to confirm the feasibility at present

High brightness electron accelerator

International Nuclear Information System (INIS)

Sheffield, R.L.; Carlsten, B.E.; Young, L.M.

1994-01-01

A compact high brightness linear accelerator is provided for use, e.g., in a free electron laser. The accelerator has a first plurality of accelerating cavities having end walls with four coupling slots for accelerating electrons to high velocities in the absence of quadrupole fields. A second plurality of cavities receives the high velocity electrons for further acceleration, where each of the second cavities has end walls with two coupling slots for acceleration in the absence of dipole fields. The accelerator also includes a first cavity with an extended length to provide for phase matching the electron beam along the accelerating cavities. A solenoid is provided about the photocathode that emits the electrons, where the solenoid is configured to provide a substantially uniform magnetic field over the photocathode surface to minimize emittance of the electrons as the electrons enter the first cavity. 5 figs

Using octupoles for background control in linear colliders -- An exploratory conceptual study

International Nuclear Information System (INIS)

Pitthan, R.

2000-01-01

If one adds a suited Octupole (or an even higher multipole) lattice to linear collider Quadrupole FODO lattices, the amplifying properties of the combined lattice drive particles in the tails, but not those in the core, into resonant losses. This approach is quite different in concept and beam dynamics impact from past proposed use of non-linear elements for collimation. This non-traditional scheme for background control has the added advantage that most, or maybe all, of the Halo collimation can be done using the lever arm of the real estate of the main accelerators, thus reducing the costly length of a separate dedicated collimation section and also unifying machine protection and background control. Simulations of particle distributions are presented. This approach requires cooperation by the designers of the accelerators, the beam delivery system, and the Detector, because a careful balance between sometimes conflicting requirements has to be found. As a second component of this approach the use of Octupoles right before the final focusing Quadrupoles is proposed in order to enlarge the effective beam stay clear by a factor of 2--3, thus reducing the requirements for collimation. This concept would reduce the requirement for collimation but simulation have not been carried out here in detail. To further explore and implement this concept will require a considerable effort in manpower, possibly comparable to, although less in scope, than the effort to develop the NLC RF or the CLIC RF schemes

Accelerator developments since the ZGS by ZGS people

International Nuclear Information System (INIS)

Cho, Y.

1994-01-01

The ZGS was a facility, as well as an organization, where people got together to pursue a common goal of doing exciting science of the day. In this note, the authors describe notable events related to accelerators and accelerator people since the closing of the ZGS program some 15 years ago. Many of the same ZGS people have been carrying out the state-of-the art accelerator work around the Laboratory with the same dedication that characterized their work in the earlier days. First the authors describe how the activities were re-organized after the closing of the ZGS, the migration of people, and the organizational evolution since that time. Doing this shows the similarity between the birth of the ZGS and the birth of the Advanced Photon Source (APS). Then, some of the accelerator work by the former ZGS people are described. These include: (1) Intense Pulsed Neutron Source (IPNS), (2) GeV Electron Microtron (GEM), (3) Wake Field Accelerator Test Facility, (4) Advanced Photon Source, and (5) IPNS Upgrade

Turkey: Background and U.S. Relations

Science.gov (United States)

2016-08-26

rate hikes . 71 Most analyses of Turkey’s economy express optimism about its fiscal position and banking system, while noting that Turkey’s...Turkish officials have threatened to curtail U.S. access to Turkish bases. Calculations regarding the costs and benefits to the United States of a U.S...of diplomatic relations. Reportedly, Vice President Joe Biden facilitated the rapprochement in part due to potential mutual benefits anticipated by

Argentina: Background and U.S. Relations

Science.gov (United States)

2016-09-06

Venezuela . For some observers, Macri’s election and policy changes signaled an ebbing of the so-called pink tide populist leftist governments in the region...2002 but also was characterized by protectionist and unorthodox economic policies and at times difficult relations with the United States...Peronist (Justicialist Party, PJ) senator selected by Congress to fill out the remainder of President de la Rúa’s term, implemented policies that

Differential effects of tissue plasminogen activator and streptokinase on infarct size and on rate of enzyme release: influence of early infarct related artery patency : The GUSTO Enzyme Substudy

NARCIS (Netherlands)

T. Baardman (Taco); W.T. Hermens (Wim); G.P. Molhoek; G. Grollier (Gilles); M.E. Pfisterer (Matthias); M.L. Simoons (Maarten); T. Lenderink (Timo)

1996-01-01

textabstractBACKGROUND: The recent international GUSTO trial of 41,021 patients with acute myocardial infarction demonstrated improved 90-min infarct related artery patency as well as reduced mortality in patients treated with an accelerated regimen of tissue plasminogen activator, compared to

Linear accelerators for TeV colliders. Revision

International Nuclear Information System (INIS)

Wilson, P.B.

1985-10-01

The basic scaling relations for important linear collider design parameters are introduced. Some of the basic concepts concerning the design of accelerating structures are presented, and breakdown limitations are discussed. Rf power sources are considered. Some of the key concepts of wakefield accelerators are discussed, and some examples of wake fields for typical linac structures are presented. Some general concepts concerning emittance, and the limitations on the emittance that can be obtained from linac guns and damping rings are discussed. 49 refs., 15 figs

Multipactor Physics, Acceleration, and Breakdown in Dielectric-Loaded Accelerating Structures

International Nuclear Information System (INIS)

Fischer, Richard P.; Gold, Steven H.

2016-01-01

The objective of this 3-year program is to study the physics issues associated with rf acceleration in dielectric-loaded accelerating (DLA) structures, with a focus on the key issue of multipactor loading, which has been found to cause very significant rf power loss in DLA structures whenever the rf pulsewidth exceeds the multipactor risetime (~10 ns). The experiments are carried out in the X-band magnicon laboratory at the Naval Research Laboratory (NRL) in collaboration with Argonne National Laboratory (ANL) and Euclid Techlabs LLC, who develop the test structures with support from the DoE SBIR program. There are two main elements in the research program: (1) high-power tests of DLA structures using the magnicon output (20 MW @11.4 GHz), and (2) tests of electron acceleration in DLA structures using relativistic electrons from a compact X-band accelerator. The work during this period has focused on a study of the use of an axial magnetic field to suppress multipactor in DLA structures, with several new high power tests carried out at NRL, and on preparation of the accelerator for the electron acceleration experiments.