WorldWideScience

Sample records for acceleration mechanics

  1. An introduction to acceleration mechanisms

    International Nuclear Information System (INIS)

    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

  2. The wake field acceleration mechanism

    International Nuclear Information System (INIS)

    The wake fields of dense bunches of relativistic electrons are used to accelerate secondary beams of positrons and electrons. The basic principle is the transformation of wake forces by means of geometric structures with different impedances at different locations. In such wake field transformers beams of a few GeV energy can accelerate secondary beams to ten times the energy of the driving particles. Two 50 GeV colliding beam linear accelerators based on this mechanism occupy less than 1300 meters total length. (orig.)

  3. Mechanical Design of Superconducting Accelerator Magnets

    OpenAIRE

    Toral, Fernando

    2015-01-01

    This paper is about the mechanical design of superconducting accelerator magnets. First, we give a brief review of the basic concepts and terms. In the following sections, we describe the particularities of the mechanical design of different types of superconducting accelerator magnets: solenoids, cos-theta, superferric, and toroids. Special attention is given to the pre-stress principle, which aims to avoid the appearance of tensile stresses in the superconducting coils. A case study on a co...

  4. Mechanical Design of Superconducting Accelerator Magnets

    CERN Document Server

    Toral, F

    2014-01-01

    This paper is about the mechanical design of superconducting accelerator magnets. First, we give a brief review of the basic concepts and terms. In the following sections, we describe the particularities of the mechanical design of different types of superconducting accelerator magnets: solenoids, costheta, superferric, and toroids. Special attention is given to the pre-stress principle, which aims to avoid the appearance of tensile stresses in the superconducting coils. A case study on a compact superconducting cyclotron summarizes the main steps and the guidelines that should be followed for a proper mechanical design. Finally, we present some remarks on the measurement techniques.

  5. Mechanisms of thrombolysis acceleration by cavitation

    Science.gov (United States)

    Weiss, Hope; Selvaraj, Prashanth; Ahadi, Golnaz; Voie, Arne; Hoelscher, Thilo; Okita, Kohei; Matsumoto, Yoichiro; Szeri, Andrew

    2012-11-01

    Recent studies, in vitro and in vivo, have shown that High Intensity Focused Ultrasound (HIFU) accelerates thrombolysis, the dissolution of blood clots, for ischemic stroke. Although the mechanisms are not fully understood, cavitation is thought to play an important role in sonothrombolysis. The damage to a blood clot's fibrin fiber network from cavitation in a HIFU field is studied using two independent approaches for an embedded bubble. One method is extended to the more important scenario of a bubble outside a blood clot that collapses asymmetrically creating a jet towards the clot. There is significantly more damage potential from a bubble undergoing cavitation collapse outside the clot compared to a rapidly expanding bubble embedded within the clot structure. Also, the effects of the physical properties of skull bone when a HIFU wave propagates through it are examined by use of computer simulation. The dynamics of a test bubble placed at the focus is used in understanding of the pressure field. All other things being equal, the analysis suggests that skull thickness can alter the wave at the focus, which in turn can change the nature of cavitation bubble dynamics and the amount of energy available for clot damage. Now at MSOE.

  6. Non-thermal acceleration mechanisms in supernova remnant shells

    OpenAIRE

    Decourchelle, Anne

    2008-01-01

    A review of the main issues in the field of particle acceleration in Supernova Remnants is provided in the context of future X-ray observations with Simbol-X. After a summary of the nonthermal acceleration mechanisms at work, I briefly review the observations of supernova remnants in hard X-rays and in gamma rays. Open issues are discussed in this framework.

  7. Mechanical power output during running accelerations in wild turkeys.

    Science.gov (United States)

    Roberts, Thomas J; Scales, Jeffrey A

    2002-05-01

    We tested the hypothesis that the hindlimb muscles of wild turkeys (Meleagris gallopavo) can produce maximal power during running accelerations. The mechanical power developed during single running steps was calculated from force-plate and high-speed video measurements as turkeys accelerated over a trackway. Steady-speed running steps and accelerations were compared to determine how turkeys alter their running mechanics from a low-power to a high-power gait. During maximal accelerations, turkeys eliminated two features of running mechanics that are characteristic of steady-speed running: (i) they produced purely propulsive horizontal ground reaction forces, with no braking forces, and (ii) they produced purely positive work during stance, with no decrease in the mechanical energy of the body during the step. The braking and propulsive forces ordinarily developed during steady-speed running are important for balance because they align the ground reaction force vector with the center of mass. Increases in acceleration in turkeys correlated with decreases in the angle of limb protraction at toe-down and increases in the angle of limb retraction at toe-off. These kinematic changes allow turkeys to maintain the alignment of the center of mass and ground reaction force vector during accelerations when large propulsive forces result in a forward-directed ground reaction force. During the highest accelerations, turkeys produced exclusively positive mechanical power. The measured power output during acceleration divided by the total hindlimb muscle mass yielded estimates of peak instantaneous power output in excess of 400 W kg(-1) hindlimb muscle mass. This value exceeds estimates of peak instantaneous power output of turkey muscle fibers. The mean power developed during the entire stance phase increased from approximately zero during steady-speed runs to more than 150 W kg(-1) muscle during the highest accelerations. The high power outputs observed during accelerations

  8. Diagnostics for studies of novel laser ion acceleration mechanisms

    International Nuclear Information System (INIS)

    Diagnostic for investigating and distinguishing different laser ion acceleration mechanisms has been developed and successfully tested. An ion separation wide angle spectrometer can simultaneously investigate three important aspects of the laser plasma interaction: (1) acquire angularly resolved energy spectra for two ion species, (2) obtain ion energy spectra for multiple species, separated according to their charge to mass ratio, along selected axes, and (3) collect laser radiation reflected from and transmitted through the target and propagating in the same direction as the ion beam. Thus, the presented diagnostic constitutes a highly adaptable tool for accurately studying novel acceleration mechanisms in terms of their angular energy distribution, conversion efficiency, and plasma density evolution

  9. High proton energies from cone targets: electron acceleration mechanisms

    International Nuclear Information System (INIS)

    Recent experiments in the Trident laser facility (Los Alamos National Laboratory) have shown that hollow conical targets with a flat top at the tip can enhance the maximum energy of proton beams created during the interaction of an ultra-intense short laser pulse with the target (Gaillard S A et al 2011 Phys. Plasmas 18 056710). The proton energies that have been seen in these experiments are the highest energies observed so far in laser-driven proton acceleration. This is attributed to a new acceleration mechanism, direct light pressure acceleration of electrons (DLLPA), which increases the number and energy of hot electrons that drive the proton acceleration. This acceleration process of protons due to a two-temperature sheath formed at the flat-top rear side is very robust and produces a large number of protons per shot, similar to what is regularly observed in target normal sheath acceleration (Hatchett S P et al 2000 Phys. Plasmas 7 2076, Maksimchuk A et al 2000 Phys. Rev. Lett. 84 4108, Snavely R A et al 2000 Phys. Rev. Lett. 85 2945) with flat foils. In this paper, we investigate the electron kinetics during DLLPA, showing that they are governed by two mechanisms, both of which lead to continuous electron acceleration along the inner cone wall. Based on our model, we predict the scaling of the hot electron temperature and ion maximum energy with both laser and target geometrical parameters. The scaling of T=mec02a02/4 with the laser strength parameter a0 leads to an ion energy scaling that surpasses that of some recently proposed acceleration mechanisms such as radiation pressure acceleration (RPA), while in addition the maximum electron energy is found to scale linearly with the length of the cone neck. We find that when optimizing parameters, high proton energies suitable for applications can be reached using compact short-pulse laser systems with pulse durations of only a few tens to hundreds of laser periods. (paper)

  10. On the novel mechanism of acceleration of cosmic particles

    CERN Document Server

    Osmanov, Z

    2015-01-01

    A novel model of particle acceleration in the rotating magnetospheres of active galactic nuclei (AGN) and pulsars is constructed. The particle energies may be boosted up to enormous energies in a several step mechanism. In the first stage, the Langmuir waves are centrifugally excited and amplified by means of a parametric process that efficiently pumps rotational energy to excite electrostatic fields. By considering the pulsars it is shown that the Langmuir waves very soon Landau damp on the relativistic electrons already present in a magnetosphere. It has been found that the process is so efficient that no energy losses might affect the mechanism of particle acceleration. Applying typical parameters for young pulsars we have shown that by means of this process the electrons might achieve energies of the order of $10^{18}$ eV. The situation in AGN magnetospheres is slightly different. In the second stage, the process of "Langmuir collapse" develops, creating appropriate conditions for transferring electric en...

  11. Young Supernovae as Experimental Sites to Study Electron Acceleration Mechanism

    OpenAIRE

    Maeda, Keiichi

    2012-01-01

    Radio emissions from young supernovae (~ 1 year after the explosion) show a peculiar feature in the relativistic electron population at a shock wave, where their energy distribution is steeper than typically found in supernova remnants (SNRs) and than the prediction from the standard diffusive shock acceleration (DSA) mechanism. This is especially established for a class of stripped envelope supernovae (SNe IIb/Ib/Ic) where a combination of high shock velocity and low circumstellar material (...

  12. Mechanical stability study for Integrable Optics Test Accelerator at Fermilab

    CERN Document Server

    McGee, M W; Carlson, K; Leibfritz, J; Nobrega, L; Valishev, A

    2016-01-01

    The Integrable Optics Test Accelerator (IOTA) is proposed for operation at Fermilab. The goal of IOTA is to create practical nonlinear accelerator focusing systems with a large frequency spread and stable particle motion. The IOTA is a 40 m circumference, 150 MeV (e-), 2.5 MeV (p+) diagnostic test ring. A heavy low frequency steel floor girder is proposed as the primary tier for IOTA device component support. Two design lengths; (8) 3.96 m and (2) 3.1 m long girders with identical cross section completely encompass the ring. This study focuses on the 3.96 m length girder and the development of a working prototype. Hydrostatic Level Sensor (HLS), temperature, metrology and fast motion measurements characterize the anticipated mechanical stability of the IOTA ring.

  13. Mechanical Stability Study for Integrable Optics Test Accelerator at Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    McGee, Mike [Fermilab; Andrews, Richard [Fermilab; Carlson, Kermit [Fermilab; Leibfritz, Jerry [Fermilab; Nobrega, Lucy [Fermilab; Valishev, Alexander [Fermilab

    2016-07-01

    The Integrable Optics Test Accelerator (IOTA) is proposed for operation at Fermilab. The goal of IOTA is to create practical nonlinear accelerator focusing systems with a large frequency spread and stable particle motion. The IOTA is a 40 m circumference, 150 MeV (e-), 2.5 MeV (p⁺) diagnostic test ring. A heavy low frequency steel floor girder is proposed as the primary tier for IOTA device component support. Two design lengths; (8) 4 m and (2) 2.8 m long girders with identical cross section completely encompass the ring. This study focuses on the 4 m length girder and the development of a working prototype. Hydrostatic Level Sensor (HLS), temperature, metrology and fast motion measurements characterize the anticipated mechanical stability of the IOTA ring.

  14. A "slingshot" laser-driven acceleration mechanism of plasma electrons

    Science.gov (United States)

    Fiore, Gaetano; De Nicola, Sergio

    2016-09-01

    We briefly report on the recently proposed Fiore et al. [1] and Fiore and De Nicola [2] electron acceleration mechanism named "slingshot effect": under suitable conditions the impact of an ultra-short and ultra-intense laser pulse against the surface of a low-density plasma is expected to cause the expulsion of a bunch of superficial electrons with high energy in the direction opposite to that of the pulse propagation; this is due to the interplay of the huge ponderomotive force, huge longitudinal field arising from charge separation, and the finite size of the laser spot.

  15. An Alternative Mechanism for Accelerated Carbon Sequestration in Concrete

    Energy Technology Data Exchange (ETDEWEB)

    Haselbach, Liv M.; Thomle, Jonathan N.

    2014-07-01

    The increased rate of carbon dioxide sequestration (carbonation) is desired in many primary and secondary life applications of concrete in order to make the life cycle of concrete structures more carbon neutral. Most carbonation rate studies have focused on concrete exposed to air under various conditions. An alternative mechanism for accelerated carbon sequestration in concrete was investigated in this research based on the pH change of waters in contact with pervious concrete which have been submerged in carbonate laden waters. The results indicate that the concrete exposed to high levels of carbonate species in water may carbonate faster than when exposed to ambient air, and that the rate is higher with higher concentrations. Validation of increased carbon dioxide sequestration was also performed via thermogravimetric analysis (TGA). It is theorized that the proposed alternative mechanism reduces a limiting rate effect of carbon dioxide dissolution in water in the micro pores of the concrete.

  16. Consistency analysis of accelerated degradation mechanism based on gray theory

    Institute of Scientific and Technical Information of China (English)

    Yunxia Chen; Hongxia Chen; Zhou Yang; Rui Kang; Yi Yang

    2014-01-01

    A fundamental premise of an accelerated testing is that the failure mechanism under elevated and normal stress levels should remain the same. Thus, verification of the consistency of failure mechanisms is essential during an accelerated testing. A new consistency analysis method based on the gray theory is pro-posed for complex products. First of al , existing consistency ana-lysis methods are reviewed with a focus on the comparison of the differences among them. Then, the proposed consistency ana-lysis method is introduced. Two effective gray prediction models, gray dynamic model and new information and equal dimensional (NIED) model, are adapted in the proposed method. The process to determine the dimension of NIED model is also discussed, and a decision rule is expanded. Based on that, the procedure of ap-plying the new consistent analysis method is developed. Final y, a case study of the consistency analysis of a reliability enhancement testing is conducted to demonstrate and validate the proposed method.

  17. Accelerator

    International Nuclear Information System (INIS)

    The invention claims equipment for stabilizing the position of the front covers of the accelerator chamber in cyclic accelerators which significantly increases accelerator reliability. For stabilizing, it uses hydraulic cushions placed between the electromagnet pole pieces and the front chamber covers. The top and the bottom cushions are hydraulically connected. The cushions are disconnected and removed from the hydraulic line using valves. (J.P.)

  18. New mechanism of acceleration of particles by stellar black holes

    CERN Document Server

    Osmanov, Z

    2016-01-01

    In this paper we study efficiency of particle acceleration in the magnetospheres of stellar mass black holes. For this purpose we consider the linearized set of the Euler equation, continuity equation and Poisson equation respectively. After introducing the varying relativistic centrifugal force, we show that the charge separation undergoes the parametric instability, leading to generation of centrifugally excited Langmuir waves. It is shown that these waves, via the Langmuir collapse damp by means of the Landau damping, as a result energy transfers to particles accelerating them to energies of the order of $10^{16}$eV.

  19. Mechanical stability study for Integrable Optics Test Accelerator at Fermilab

    OpenAIRE

    McGee, M. W.; Andrews, R; Carlson, K.; Leibfritz, J.; Nobrega, L.; Valishev, A.

    2016-01-01

    The Integrable Optics Test Accelerator (IOTA) is proposed for operation at Fermilab. The goal of IOTA is to create practical nonlinear accelerator focusing systems with a large frequency spread and stable particle motion. The IOTA is a 40 m circumference, 150 MeV (e-), 2.5 MeV (p+) diagnostic test ring. A heavy low frequency steel floor girder is proposed as the primary tier for IOTA device component support. Two design lengths; (8) 3.96 m and (2) 3.1 m long girders with identical cross secti...

  20. Properties and Acceleration Mechanism of Cement Mortar Added with Low Alkaline Liquid State Setting Accelerator

    Institute of Scientific and Technical Information of China (English)

    PAN Zhihua; WANG Xuebing; LIU Weiqing

    2014-01-01

    Low alkaline liquid state setting accelerator(LSA) for Portland cement was prepared in laboratory from aqueous solution of several inorganic sulfate salts and some organic chemical substances. Properties of cement with addition of LSA relating to its setting time and strength development as well as its resistance to sulfate attack for short and long term exposure were experimentally examined. The experimental results showed that 5%-7%addition of LSA significantly accelerated the initial and final setting of Portland cement in the presence or absence of the blending of mineral admixtures, the initial and final setting time being less than 3 min and 6 min respectively. Meanwhile, the early 1 day curing age compressive strength increased remarkably by 20%, while the late 28th day curing age compressive strength remained almost unchanged as compared with that of the reference accelerator free cement mortar specimen. Furthermore, mortar specimens of cement added with LSA and exposed to 5%Na2SO4 solution showed their excellent resistance to sulfate attack, with their short and long term curing age resistance coefficient to sulfate attack being around 1.04 to 1.17, all larger than 1.0. XRD analysis on hardened cement paste specimens at very early curing ages of several minutes disclosed the existence of more ettringite in specimens added with LSA than that of the reference specimens, meanwhile SEM observation also revealed the existence of well crystallized ettringite at very early hydration stage, suggesting that the accelerated setting of Portland cement can be attributed to the early and rapid formation of ettringite over the whole cement paste matrix due to the introduction of LSA. MIP measurement revealed that hardened cement paste specimens with the addition of LSA presented less medium diameter pores, more proportion of small pores and less proportion of large capillary pores, which is in a very good coincidence with the improvement of strength development of

  1. A Massively Parallel Solver for the Mechanical Harmonic Analysis of Accelerator Cavities

    Energy Technology Data Exchange (ETDEWEB)

    Kononenko, O. [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-02-17

    ACE3P is a 3D massively parallel simulation suite that developed at SLAC National Accelerator Laboratory that can perform coupled electromagnetic, thermal and mechanical study. Effectively utilizing supercomputer resources, ACE3P has become a key simulation tool for particle accelerator R and D. A new frequency domain solver to perform mechanical harmonic response analysis of accelerator components is developed within the existing parallel framework. This solver is designed to determine the frequency response of the mechanical system to external harmonic excitations for time-efficient accurate analysis of the large-scale problems. Coupled with the ACE3P electromagnetic modules, this capability complements a set of multi-physics tools for a comprehensive study of microphonics in superconducting accelerating cavities in order to understand the RF response and feedback requirements for the operational reliability of a particle accelerator. (auth)

  2. The Mechanisms of Electron Acceleration During Multiple X Line Magnetic Reconnection with a Guide Field

    CERN Document Server

    Wang, Huanyu; Huang, Can; Wang, Shui

    2016-01-01

    The interactions between magnetic islands are considered to play an important role in electron acceleration during magnetic reconnection. In this paper, two-dimensional (2-D) particle-in-cell (PIC) simulations are performed to study electron acceleration during multiple X line reconnection with a guide field. The electrons remain almost magnetized, and we can then analyze the contributions of the parallel electric field, Fermi and betatron mechanisms to electron acceleration during the evolution of magnetic reconnection by comparing with a guide-center theory. The results show that with the proceeding of magnetic reconnection, two magnetic islands are formed in the simulation domain. The electrons are accelerated by both the parallel electric field in the vicinity of the X lines and Fermi mechanism due to the contraction of the two magnetic islands. Then the two magnetic islands begin to merge into one, and in such a process electrons can be accelerated by the parallel electric field and betatron mechanisms. ...

  3. Drift mechanism of laser-induced electron acceleration in vacuum

    Science.gov (United States)

    Morgovsky, L.

    2015-12-01

    Laser-induced electron acceleration in vacuum is possible due to the ejection of electrons from the beam as a consequence of the transverse drift orthogonal to the propagation direction. The transverse drift is derived from the general solution of the equations of motion of the electrons in the field of a plane electromagnetic wave with arbitrary polarization. It is shown that the energy gain is proportional to the square of the field strength additionally modulated by the function of the injection and ejection phases. In particular, for a linearly polarized beam this function is reduced to the squared difference between the cosines of these phases. The finite laser pulse duration restricts the range of the field strength suitable for direct electron acceleration in vacuum within certain limits. It is demonstrated that the high efficiency of energy transfer from the laser wave into the kinetic energy of the accelerated electrons demands phase matching between the electron quiver phase at the exit point and the phase of the energy transfer.

  4. Mechanism of Isoflavone Aglycone's Effect on Cognitive Performance of Senescence-Accelerated Mice

    Science.gov (United States)

    Yang, Hong; Jin, Guifang; Ren, Dongdong; Luo, Sijing; Zhou, Tianhong

    2011-01-01

    This study investigated the effect of isoflavone aglycone (IA) on the learning and memory performance of senescence-accelerated mice, and explored its neural protective mechanism. Results showed that SAM-P/8 senescence-accelerated mice treated with IA performed significantly better in the Y-maze cognitive test than the no treatment control (P less…

  5. Acceleration of Thermal Protons By Generic Phenomenological Mechanisms

    CERN Document Server

    Petrosian, Vahé

    2016-01-01

    We investigate heating and acceleration of protons from a thermal gas with a generic diffusion and acceleration model, and subject to Coulomb scattering and energy loss, as was carried out in Petrosian & East (2008) for electrons. As protons gain energy their loss to electrons becomes important. Thus, we need to solve the coupled proton-electron kinetic equation. We numerically solve the coupled Fokker-Plank equations and computes the time evolution of the spectra of both particles. We show that this can lead to a quasi-thermal component plus a high energy nonthermal tail. We determine the evolution of nonthermal tail and the quasi-thermal component. The results may be used to explore the possibility of inverse bremsstrahlung radiation as a source of hard X-ray emissions from hot sources such as solar flares, accretion disk coronas and the intracluster medium of galaxy clusters. We find that emergence of nonthermal protons is accompanied by excessive heating of the entire plasma, unless the turbulence nee...

  6. THE MECHANISMS OF ELECTRON ACCELERATION DURING MULTIPLE X LINE MAGNETIC RECONNECTION WITH A GUIDE FIELD

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Huanyu; Lu, Quanming; Huang, Can; Wang, Shui, E-mail: qmlu@ustc.edu.cn [CAS Key Lab of Geospace Environment, Department of Geophysics and Planetary Science, University of Science and Technology of China, Hefei 230026 (China)

    2016-04-20

    The interactions between magnetic islands are considered to play an important role in electron acceleration during magnetic reconnection. In this paper, two-dimensional particle-in-cell simulations are performed to study electron acceleration during multiple X line reconnection with a guide field. Because the electrons remain almost magnetized, we can analyze the contributions of the parallel electric field, Fermi, and betatron mechanisms to electron acceleration during the evolution of magnetic reconnection through comparison with a guide-center theory. The results show that with the magnetic reconnection proceeding, two magnetic islands are formed in the simulation domain. Next, the electrons are accelerated by both the parallel electric field in the vicinity of the X lines and the Fermi mechanism due to the contraction of the two magnetic islands. Then, the two magnetic islands begin to merge into one, and, in such a process, the electrons can be accelerated by both the parallel electric field and betatron mechanisms. During the betatron acceleration, the electrons are locally accelerated in the regions where the magnetic field is piled up by the high-speed flow from the X line. At last, when the coalescence of the two islands into one big island finishes, the electrons can be further accelerated by the Fermi mechanism because of the contraction of the big island. With the increase of the guide field, the contributions of the Fermi and betatron mechanisms to electron acceleration become less and less important. When the guide field is sufficiently large, the contributions of the Fermi and betatron mechanisms are almost negligible.

  7. Research on the Mechanism of Accelerator for Photocurable Resin in 3D Printing

    Institute of Scientific and Technical Information of China (English)

    LIU Hai-tao; MO Jian-hua; HUANG Xiao-mao

    2009-01-01

    The photopolymerization kinetics of cycloaliphatic epoxide and oxetane with accelerators were investigated with Real-time Fourier transform infrared spectroscopy (RT-FTIR). The consumption rates of epoxy group and oxetane group as a function of time were obtained by monitoring of the absorption peaks in the 789 cm-1 and 981 cm-1. The effect of accelerators type and the accelerating mechanism were discussed. In general, benzyl alcohol and its analogues with electron-donating substituents are useful accelerators for the cationic polymerization of cycloaliphatic epoxide and oxetane. Activated monomer mechanism and free-radical chain-induced decomposition of onium salt cationic photoinitiator account for the observed accelerating effect on the polymerization rate.

  8. Delayed and accelerated aging share common longevity assurance mechanisms

    NARCIS (Netherlands)

    B. Schumacher; I. van der Pluijm; M.J. Moorhouse; T. Kosteas; A.R. Robinson; Y. Suh; T.M. Breit; H. van Steeg; L.J. Niedernhofer; W. van IJcken; A. Bartke; S.R. Spindler; J.H.J. Hoeijmakers; G.T.J. van der Horst; G.A. Garinis

    2008-01-01

    Mutant dwarf and calorie-restricted mice benefit from healthy aging and unusually long lifespan. In contrast, mouse models for DNA repair-deficient progeroid syndromes age and die prematurely. To identify mechanisms that regulate mammalian longevity, we quantified the parallels between the genome-wi

  9. Studies on mechanisms of the laser particle acceleration; Untersuchungen zu Mechanismen der Laser-Teilchenbeschleunigung

    Energy Technology Data Exchange (ETDEWEB)

    Aurand, Bastian

    2012-06-20

    Within the last decade, many developments towards higher energies and particle numbers paved the way of particle acceleration performed by high intensity laser systems. Up to now, the process of a field-induced acceleration process (Target-Normal-Sheath-Acceleration (TNSA)) is investigated the most. Acceleration occurs as a consequence of separation of charges on a surface potential. Here, the broad energy spectrum is a problem not yet overcome although many improvements were achieved. Calculations for intensities higher than 10{sup 20..21} W/cm{sup 2} give hint that Radiation-Pressure-Acceleration (RPA) may lead to a sharper, monoenergetic energy spectrum. Within the framework of this thesis, the investigation of the acceleration mechanism is studied experimentally in the intensity range of 10{sup 19} W/cm{sup 2}. Suitable targets were developed and applied for patent. A broad range of parameters was scanned by means of high repetition rates together with an adequate laser system to provide high statistics of several thousands of shots, and the dependence of target material, intensity, laser polarisation and pre plasma-conditions was verified. Comparisons with 2-d numeric simulations lead to a model of the acceleration process which was analyzed by several diagnostic methods, giving clear evidence for a new, not field-induced acceleration process. In addition, a system for a continuous variation of the polarization based on reflective optics was developed in order to overcome the disadvantages of retardation plates, and their practicability of high laser energies can be achieved.

  10. YOUNG SUPERNOVAE AS EXPERIMENTAL SITES FOR STUDYING THE ELECTRON ACCELERATION MECHANISM

    International Nuclear Information System (INIS)

    Radio emissions from young supernovae (∼<1 year after the explosion) show a peculiar feature in the relativistic electron population at a shock wave, where their energy distribution is steeper than typically found in supernova remnants and than that predicted from the standard diffusive shock acceleration (DSA) mechanism. This has been especially established for the case for a class of stripped envelope supernovae (SNe IIb/Ib/Ic), where a combination of high shock velocity and low circumstellar material density makes it easier to derive the intrinsic energy distribution than in other classes of SNe. We suggest that this apparent discrepancy reflects a situation where the low energy electrons, before being accelerated by the DSA-like mechanism, are responsible for the radio synchrotron emission from young SNe, and that studying young SNe sheds light on the still-unresolved electron injection problem in the acceleration theory of cosmic rays. We suggest that the electron's energy distribution could be flattened toward high energy, most likely around 100 MeV, which marks a transition from inefficient to efficient acceleration. Identifying this feature will be a major advance in understanding the electron acceleration mechanism. We suggest two further probes: (1) millimeter/submillimeter observations in the first year after the explosion and (2) X-ray observations at about one year and thereafter. We show that these are reachable by ALMA and Chandra for nearby SNe.

  11. Constraining sources of ultrahigh energy cosmic rays and shear acceleration mechanism of particles in relativistic jets

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ruoyu

    2015-06-10

    Ultrahigh energy cosmic rays are extreme energetic particles from outer space. They have aroused great interest among scientists for more than fifty years. However, due to the rarity of the events and complexity of the process of their propagation to Earth, they are still one of the biggest puzzles in modern high energy astrophysics. This dissertation is dedicated to study the origin of ultrahigh energy cosmic rays from various aspects. Firstly, we discuss a possible link between recently discovered sub-PeV/PeV neutrinos and ultrahigh energy cosmic rays. If these two kinds of particles share the same origin, the observation of neutrinos may provide additional and non-trivial constraints on the sources of ultrahigh energy cosmic rays. Secondly, we jointly employ the chemical composition measurement and the arrival directions of ultrahigh energy cosmic rays, and find a robust upper limit for distances of sources of ultrahigh energy cosmic rays above ∝55 EeV, as well as a lower limit for their metallicities. Finally, we study the shear acceleration mechanism in relativistic jets, which is a more efficient mechanism for the acceleration of higher energy particle. We compute the acceleration efficiency and the time-dependent particle energy spectrum, and explore the feature of synchrotron radiation of the accelerated particles. The possible realizations of this mechanism for acceleration of ultrahigh energy cosmic rays in different astrophysical environments is also discussed.

  12. Centripetal Acceleration Reaction: An Effective and Robust Mechanism for Flapping Flight in Insects.

    Directory of Open Access Journals (Sweden)

    Chao Zhang

    Full Text Available Despite intense study by physicists and biologists, we do not fully understand the unsteady aerodynamics that relate insect wing morphology and kinematics to lift generation. Here, we formulate a force partitioning method (FPM and implement it within a computational fluid dynamic model to provide an unambiguous and physically insightful division of aerodynamic force into components associated with wing kinematics, vorticity, and viscosity. Application of the FPM to hawkmoth and fruit fly flight shows that the leading-edge vortex is the dominant mechanism for lift generation for both these insects and contributes between 72-85% of the net lift. However, there is another, previously unidentified mechanism, the centripetal acceleration reaction, which generates up to 17% of the net lift. The centripetal acceleration reaction is similar to the classical inviscid added-mass in that it depends only on the kinematics (i.e. accelerations of the body, but is different in that it requires the satisfaction of the no-slip condition, and a combination of tangential motion and rotation of the wing surface. Furthermore, the classical added-mass force is identically zero for cyclic motion but this is not true of the centripetal acceleration reaction. Furthermore, unlike the lift due to vorticity, centripetal acceleration reaction lift is insensitive to Reynolds number and to environmental flow perturbations, making it an important contributor to insect flight stability and miniaturization. This force mechanism also has broad implications for flow-induced deformation and vibration, underwater locomotion and flows involving bubbles and droplets.

  13. Mechanical design and construction of a 200 mA, 100 keV, dc, negative ion accelerator

    International Nuclear Information System (INIS)

    A volume production source and a 100 keV, dc, accelerator together with an additional, modular, 100 keV, electro static focused accelerator provide a starting point for a high energy H-/D- beam-line (200 keV to 800 keV), intended for fusion energy applications. The 100 keV accelerator tests started in June 1987. The mechanical design and construction of the accelerator is described. 3 refs., 8 figs

  14. Assembly Test of Elastic Averaging Technique to Improve Mechanical Alignment for Accelerating Structure Assemblies in CLIC

    CERN Document Server

    Huopana, J

    2010-01-01

    The CLIC (Compact LInear Collider) is being studied at CERN as a potential multi-TeV e+e- collider [1]. The manufacturing and assembly tolerances for the required RF-components are important for the final efficiency and for the operation of CLIC. The proper function of an accelerating structure is very sensitive to errors in shape and location of the accelerating cavity. This causes considerable issues in the field of mechanical design and manufacturing. Currently the design of the accelerating structures is a disk design. Alternatively it is possible to create the accelerating assembly from quadrants, which favour the mass manufacturing. The functional shape inside of the accelerating structure remains the same and a single assembly uses less parts. The alignment of these quadrants has been previously made kinematic by using steel pins or spheres to align the pieces together. This method proved to be a quite tedious and time consuming method of assembly. To limit the number of different error sources, a meth...

  15. Working toward exposure thresholds for blast-induced traumatic brain injury: thoracic and acceleration mechanisms

    CERN Document Server

    Courtney, Michael; 10.1016/j.neuroimage.2010.05.025

    2011-01-01

    Research in blast-induced lung injury resulted in exposure thresholds that are useful in understanding and protecting humans from such injury. Because traumatic brain injury (TBI) due to blast exposure has become a prominent medical and military problem, similar thresholds should be identified that can put available research results in context and guide future research toward protecting warfighters as well as diagnosis and treatment. At least three mechanical mechanisms by which the blast wave may result in brain injury have been proposed - a thoracic mechanism, head acceleration and direct cranial transmission. These mechanisms need not be mutually exclusive. In this study, likely regions of interest for the first two mechanisms based on blast characteristics (positive pulse duration and peak effective overpressure) are developed using available data from blast experiments and related studies, including behind-armor blunt trauma and ballistic pressure wave studies. These related studies are appropriate to in...

  16. Quantitative relationship between axonal injury and mechanical response in a rodent head impact acceleration model.

    Science.gov (United States)

    Li, Yan; Zhang, Liying; Kallakuri, Srinivasu; Zhou, Runzhou; Cavanaugh, John M

    2011-09-01

    A modified Marmarou impact acceleration model was developed to study the mechanical responses induced by this model and their correlation to traumatic axonal injury (TAI). Traumatic brain injury (TBI) was induced in 31 anesthetized male Sprague-Dawley rats (392±13 g) by a custom-made 450-g impactor from heights of 1.25 m or 2.25 m. An accelerometer and angular rate sensor measured the linear and angular responses of the head, while the impact event was captured by a high-speed video camera. TAI distribution along the rostro-caudal direction, as well as across the left and right hemispheres, was determined using β-amyloid precursor protein (β-APP) immunocytochemistry, and detailed TAI injury maps were constructed for the entire corpus callosum. Peak linear acceleration 1.25 m and 2.25 m impacts were 666±165 g and 907±501 g, respectively. Peak angular velocities were 95±24 rad/sec and 124±48 rad/sec, respectively. Compared to the 2.25-m group, the observed TAI counts in the 1.25-m impact group were significantly lower. Average linear acceleration, peak angular velocity, average angular acceleration, and surface righting time were also significantly different between the two groups. A positive correlation was observed between normalized total TAI counts and average linear acceleration (R(2)=0.612, plinear and angular acceleration response of the rat head during impact, not necessarily the drop height.

  17. Coupled Mechanical-Electrochemical-Thermal Modeling for Accelerated Design of EV Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Santhanagopalan, Shriram; Zhang, Chao; Kim, Gi-Heon; Pesaran, Ahmad A.

    2015-05-03

    This presentation provides an overview of the mechanical electrochemical-thermal (M-ECT) modeling efforts. The physical phenomena occurring in a battery are many and complex and operate at different scales (particle, electrodes, cell, and pack). A better understanding of the interplay between different physics occurring at different scales through modeling could provide insight to design improved batteries for electric vehicles. Work funded by the U.S. DOE has resulted in development of computer-aided engineering (CAE) tools to accelerate electrochemical and thermal design of batteries; mechanical modeling is under way. Three competitive CAE tools are now commercially available.

  18. Thermal vacuum accelerated life test of the unit qualification model msds 3 marconi low speed mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Appleton, D.A.

    1975-01-01

    The thermal vacuum accelerated life test of a solar array unit qualification mechanism (MSDS 3) is described. Most of the test was conducted with the shaft of the mechanism rotating at one revolution per hour, which is 24 times normal speed. The test was conducted at two different temperature conditions, and included additional thermal cycling of the shaft temperature to simulate conditions of earth eclipse of a satellite in a geostationary orbit. Throughout the test there was no change in the motor power required to drive the shaft, and the electrical noise levels on the slip rings showed no significant deterioration.

  19. Physical mechanism of the transverse instability in radiation pressure ion acceleration

    CERN Document Server

    Wan, Y; Zhang, C J; Li, F; Wu, Y P; Hua, J F; Lu, W; Gu, Y Q; Silva, L O; Joshi, C; Mori, W B

    2016-01-01

    The transverse stability of the target is crucial for obtaining high quality ion beams using the laser radiation pressure acceleration (RPA) mechanism. In this letter, a theoretical model and supporting two-dimensional (2D) Particle-in-Cell (PIC) simulations are presented to clarify the physical mechanism of the transverse instability observed in the RPA process. It is shown that the density ripples of the target foil are mainly induced by the coupling between the transverse oscillating electrons and the quasi-static ions, a mechanism similar to the transverse two stream instability in the inertial confinement fusion (ICF) research. The predictions of the mode structure and the growth rates from the theory agree well with the results obtained from the PIC simulations in various regimes, indicating the model contains the essence of the underlying physics of the transverse break-up of the target.

  20. Evaluation of Dynamic Mechanical Loading as an Accelerated Test Method for Ribbon Fatigue

    Energy Technology Data Exchange (ETDEWEB)

    Bosco, Nick; Silverman, Timothy J.; Wohlgemuth, John; Kurtz, Sarah; Inoue, Masanao; Sakurai, Keiichiro; Shioda, Tsuyoshi; Zenkoh, Hirofumi; Hirota, Kusato; Miyashita, Masanori; Tadanori, Tanahashi; Suzuki, Soh; Chen, Yifeng; Verlinden, Pierre J.

    2014-12-31

    Dynamic Mechanical Loading (DML) of photovoltaic modules is explored as a route to quickly fatigue copper interconnect ribbons. Results indicate that most of the interconnect ribbons may be strained through module mechanical loading to a level that will result in failure in a few hundred to thousands of cycles. Considering the speed at which DML may be applied, this translates into a few hours of testing. To evaluate the equivalence of DML to thermal cycling, parallel tests were conducted with thermal cycling. Preliminary analysis suggests that one +/-1 kPa DML cycle is roughly equivalent to one standard accelerated thermal cycle and approximately 175 of these cycles are equivalent to a 25-year exposure in Golden Colorado for the mechanism of module ribbon fatigue.

  1. Evaluation of Dynamic Mechanical Loading as an Accelerated Test Method for Ribbon Fatigue: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Bosco, N.; Silverman, T. J.; Wohlgemuth, J.; Kurtz, S.; Inoue, M.; Sakurai, K.; Shinoda, T.; Zenkoh, H.; Hirota, K.; Miyashita, M.; Tadanori, T.; Suzuki, S.

    2015-04-07

    Dynamic Mechanical Loading (DML) of photovoltaic modules is explored as a route to quickly fatigue copper interconnect ribbons. Results indicate that most of the interconnect ribbons may be strained through module mechanical loading to a level that will result in failure in a few hundred to thousands of cycles. Considering the speed at which DML may be applied, this translates into a few hours o testing. To evaluate the equivalence of DML to thermal cycling, parallel tests were conducted with thermal cycling. Preliminary analysis suggests that one +/-1 kPa DML cycle is roughly equivalent to one standard accelerated thermal cycle and approximately 175 of these cycles are equivalent to a 25-year exposure in Golden Colorado for the mechanism of module ribbon fatigue.

  2. The Acceleration Mechanism of Resistive MHD Jets Launched from Accretion Disks

    CERN Document Server

    Kuwabara, T; Kudoh, T; Matsumoto, R

    2004-01-01

    We analyzed the results of non-linear resistive magnetohydrodynamical (MHD) simulations of jet formation to study the acceleration mechanism of axisymmetric, resistive MHD jets. The initial state is a constant angular momentum, polytropic torus threaded by weak uniform vertical magnetic fields. The time evolution of the torus is simulated by applying the CIP-MOCCT scheme extended for resistive MHD equations. We carried out simulations up to 50 rotation period at the innermost radius of the disk created by accretion from the torus. The acceleration forces and the characteristics of resistive jets were studied by computing forces acting on Lagrangian test particles. Since the angle between the rotation axis of the disk and magnetic field lines is smaller in resistive models than in ideal MHD models, magnetocentrifugal acceleration is smaller. The effective potential along a magnetic field line has maximum around $z \\sim 0.5r_0$ in resistive models, where $r_0$ is the radius where the density of the initial toru...

  3. VDE characteristics during disruption process and its underlying acceleration mechanism in the ITER-EDA tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Yukiharu; Nishio, Satoshi; Yoshino, Ryuji [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment; Kessel, C.E.; Jardin, S.C.

    1996-12-01

    The dynamic behavior of vertical displacement events (VDEs) during a disruption and acceleration mechanisms that govern VDEs in the ITER-EDA tokamak are investigated using the Tokamak Simulation Code. A sudden plasma pressure drop ({beta}{sub p} collapse) does not accelerate VDEs for the ITER tokamak. The geometry of the ITER resistive shell is shown to be suitable for preventing a {beta}{sub p} collapse-induced VDE, because the magnetic field decay n-index after the {beta}{sub p} collapse does not considerably degrade. On the other hand, it is shown that the plasma current quench (I{sub p} quench) following the energy quench can accelerate VDEs due to the vertical imbalance of the attractive force arising from the up-down asymmetric shell. The vertical location of the neutral point where the I{sub p} quench-induced VDE almost disappears is found to lie at {approx}22 cm below the plasma magnetic axis of the nominal equilibrium (Z = 1.44 m). An upward and moderate I{sub p} quench-induced VDE can be expected for the nominal configuration in the ITER-EDA tokamak. It is shown that the ITER tokamak has an advantage of avoiding the fatal damage of the complicated structures of the bottom-divertor. (author)

  4. VDE characteristics during disruption process and its underlying acceleration mechanism in the ITER-EDA tokamak

    International Nuclear Information System (INIS)

    The dynamic behavior of vertical displacement events (VDEs) during a disruption and acceleration mechanisms that govern VDEs in the ITER-EDA tokamak are investigated using the Tokamak Simulation Code. A sudden plasma pressure drop (βp collapse) does not accelerate VDEs for the ITER tokamak. The geometry of the ITER resistive shell is shown to be suitable for preventing a βp collapse-induced VDE, because the magnetic field decay n-index after the βp collapse does not considerably degrade. On the other hand, it is shown that the plasma current quench (Ip quench) following the energy quench can accelerate VDEs due to the vertical imbalance of the attractive force arising from the up-down asymmetric shell. The vertical location of the neutral point where the Ip quench-induced VDE almost disappears is found to lie at ∼22 cm below the plasma magnetic axis of the nominal equilibrium (Z = 1.44 m). An upward and moderate Ip quench-induced VDE can be expected for the nominal configuration in the ITER-EDA tokamak. It is shown that the ITER tokamak has an advantage of avoiding the fatal damage of the complicated structures of the bottom-divertor. (author)

  5. Accelerated Discovery in Photocatalysis using a Mechanism-Based Screening Method.

    Science.gov (United States)

    Hopkinson, Matthew N; Gómez-Suárez, Adrián; Teders, Michael; Sahoo, Basudev; Glorius, Frank

    2016-03-18

    Herein, we report a conceptually novel mechanism-based screening approach to accelerate discovery in photocatalysis. In contrast to most screening methods, which consider reactions as discrete entities, this approach instead focuses on a single constituent mechanistic step of a catalytic reaction. Using luminescence spectroscopy to investigate the key quenching step in photocatalytic reactions, an initial screen of 100 compounds led to the discovery of two promising substrate classes. Moreover, a second, more focused screen provided mechanistic insights useful in developing proof-of-concept reactions. Overall, this fast and straightforward approach both facilitated the discovery and aided the development of new light-promoted reactions and suggests that mechanism-based screening strategies could become useful tools in the hunt for new reactivity. PMID:27000485

  6. Accelerated Discovery in Photocatalysis using a Mechanism-Based Screening Method.

    Science.gov (United States)

    Hopkinson, Matthew N; Gómez-Suárez, Adrián; Teders, Michael; Sahoo, Basudev; Glorius, Frank

    2016-03-18

    Herein, we report a conceptually novel mechanism-based screening approach to accelerate discovery in photocatalysis. In contrast to most screening methods, which consider reactions as discrete entities, this approach instead focuses on a single constituent mechanistic step of a catalytic reaction. Using luminescence spectroscopy to investigate the key quenching step in photocatalytic reactions, an initial screen of 100 compounds led to the discovery of two promising substrate classes. Moreover, a second, more focused screen provided mechanistic insights useful in developing proof-of-concept reactions. Overall, this fast and straightforward approach both facilitated the discovery and aided the development of new light-promoted reactions and suggests that mechanism-based screening strategies could become useful tools in the hunt for new reactivity.

  7. Mechanism of Calcium Fluoride Acceleration for Vacuum Carbothermic Reduction of Magnesia

    Science.gov (United States)

    Jiang, Yun; Liu, Yu-qin; Ma, Hong-wen; Zhou, Wei-gong

    2016-04-01

    The use of a small amount of calcium fluoride as an additive greatly accelerated the reduction of magnesia during the preparation of magnesium from magnesia using the vacuum carbothermic reduction method. At 1573 K (1300 °C), the magnesia reaction rates of the samples with 1, 3, and 5 pct CaF2 were all approximately 26 pct, three times that of free CaF2, and they were arranged in order of the calcium fluoride weight percentages at 1673 K (1400 °C). The residues were analyzed using chemical analysis, XRD, SEM, EDS, and XRF. The possible acceleration mechanism was discussed. Calcium fluoride combined with magnesia and silicon dioxide to form a eutectic that melted as a channel to aid the solid-solid reaction between carbon and magnesia at approximately 1573 K (1300 °C). Calcium fluoride in the molten state offered free calcium ions and fluorine ions. Fluorine ions entered and distorted the magnesia crystal lattice. The structural strength and chemical stability of the magnesia crystal lattice decreased, which facilitated the magnesia reduction by carbon. Calcium ions were employed to generate the calcium and magnesium silicate. The easyly evaporating fluorides, including magnesium fluoride and silicon tetrafluoride, were regarded as the main reason for the loss of fluorine.

  8. The slingshot effect: a new laser-driven high energy acceleration mechanism for electrons?

    CERN Document Server

    Fiore, Gaetano; de Angelis, Umberto

    2013-01-01

    We argue that the impact of an ultra-intense and ultra-short pancake-shaped laser pulse normally onto a plasma may cause a violent expulsion of a very thin layer of surface electrons in the direction opposite to that of propagation of the pulse. In fact, the ponderomotive force exerted by the pulse first boosts all these electrons deep into the ion background distribution ("slingshot loading"); then the huge longitudinal electric force due to the charge separation (the "slingshot") does most of its work unopposed after passing of the pulse, causing their back-acceleration and expulsion ("slingshot effect") from the bulk in the backward direction with a very high, peaked and simple energy spectrum. The effect should arise also from impact onto gases or other states of matter, provided the pulse is sufficiently intense to cause locally their complete ionization. Its experimental verification seems feasible in several laboratories. If confirmed, it might be applied as an acceleration mechanism for electrons alte...

  9. The slingshot effect: A possible new laser-driven high energy acceleration mechanism for electrons

    International Nuclear Information System (INIS)

    We show that under appropriate conditions the impact of a very short and intense laser pulse onto a plasma causes the expulsion of surface electrons with high energy in the direction opposite to the one of the propagations of the pulse. This is due to the combined effects of the ponderomotive force and the huge longitudinal field arising from charge separation (“slingshot effect”). The effect should also be present with other states of matter, provided the pulse is sufficiently intense to locally cause complete ionization. An experimental test seems to be feasible and, if confirmed, would provide a new extraction and acceleration mechanism for electrons, alternative to traditional radio-frequency-based or laser-wake-field ones

  10. Modal self-excitation by nonlinear acceleration feedback in a class of mechanical systems

    Science.gov (United States)

    Malas, Anindya; Chatterjee, S.

    2016-08-01

    The article proposes an acceleration feedback based technique for exciting modal self-oscillation in a class of multi degrees-of-freedom mechanical systems. The controller comprises a bank of second-order filters and the control law is formulated as the nonlinear function of the filter output. A design methodology is developed to excite self-oscillation in any desired mode or combination of modes (mixed-mode oscillation). The choice of control parameters takes into account the control cost and robustness of the controller. The effects of structural damping on the system performance are also studied. Analytical results are confirmed by numerical simulations. An adaptive control is proposed to maintain the oscillation amplitude at the desired level.

  11. Improvement of the Error-detection Mechanism in Adults with Dyslexia Following Reading Acceleration Training.

    Science.gov (United States)

    Horowitz-Kraus, Tzipi

    2016-05-01

    The error-detection mechanism aids in preventing error repetition during a given task. Electroencephalography demonstrates that error detection involves two event-related potential components: error-related and correct-response negativities (ERN and CRN, respectively). Dyslexia is characterized by slow, inaccurate reading. In particular, individuals with dyslexia have a less active error-detection mechanism during reading than typical readers. In the current study, we examined whether a reading training programme could improve the ability to recognize words automatically (lexical representations) in adults with dyslexia, thereby resulting in more efficient error detection during reading. Behavioural and electrophysiological measures were obtained using a lexical decision task before and after participants trained with the reading acceleration programme. ERN amplitudes were smaller in individuals with dyslexia than in typical readers before training but increased following training, as did behavioural reading scores. Differences between the pre-training and post-training ERN and CRN components were larger in individuals with dyslexia than in typical readers. Also, the error-detection mechanism as represented by the ERN/CRN complex might serve as a biomarker for dyslexia and be used to evaluate the effectiveness of reading intervention programmes. Copyright © 2016 John Wiley & Sons, Ltd.

  12. Improvement of the Error-detection Mechanism in Adults with Dyslexia Following Reading Acceleration Training.

    Science.gov (United States)

    Horowitz-Kraus, Tzipi

    2016-05-01

    The error-detection mechanism aids in preventing error repetition during a given task. Electroencephalography demonstrates that error detection involves two event-related potential components: error-related and correct-response negativities (ERN and CRN, respectively). Dyslexia is characterized by slow, inaccurate reading. In particular, individuals with dyslexia have a less active error-detection mechanism during reading than typical readers. In the current study, we examined whether a reading training programme could improve the ability to recognize words automatically (lexical representations) in adults with dyslexia, thereby resulting in more efficient error detection during reading. Behavioural and electrophysiological measures were obtained using a lexical decision task before and after participants trained with the reading acceleration programme. ERN amplitudes were smaller in individuals with dyslexia than in typical readers before training but increased following training, as did behavioural reading scores. Differences between the pre-training and post-training ERN and CRN components were larger in individuals with dyslexia than in typical readers. Also, the error-detection mechanism as represented by the ERN/CRN complex might serve as a biomarker for dyslexia and be used to evaluate the effectiveness of reading intervention programmes. Copyright © 2016 John Wiley & Sons, Ltd. PMID:27072047

  13. Mechanism of self-reinforcing YORP acceleration for fast-rotating asteroids

    Science.gov (United States)

    Statler, T.; Richardson, D.; Walsh, K.; Yu, Y.; Michel, P.

    2014-07-01

    The YORP effect is an important process that directly alters the spin states, and indirectly alters the orbits, of small Solar System bodies. It has been suggested that YORP may be able simultaneously to account for the high fraction of binaries among the near-Earth-asteroid (NEA) population, the frequent radar detections of objects shaped like child's tops, and the abundance of top-shaped asteroids with binary companions. In a compelling demonstration, Walsh et al. (2008, Nature 454, 188) simulated the evolution of idealized, gravitationally bound rubble piles, to which they continually added angular momentum. The centrifugal force caused material to move from mid-latitudes toward the equator, generating the characteristic top shape. Continued spin-up caused the equatorial ridge to shed material, which reaccreted in orbit to form a binary companion. But this mechanism rests on the assumption that YORP will provide all the angular momentum needed to form axisymmetric tops, accelerate them to the mass-shedding limit, and drive enough mass into orbit to form an observable companion. This assumption is problematic, as a truly axisymmetic body would experience no YORP effect at all, and small surface changes on an object with approximate large-scale axisymmetry can easily change the sign of the torque and decelerate the spin (Statler 2009, Icarus 202, 502). So the search is on for a mechanism that can ensure a continual increase in angular momentum to overcome the stochastic effect of topographic changes. One intriguing suggestion is ''tangential YORP'' (Golubov and Krugly 2012, ApJL 752, L11), which arises from asymmetric east-west heat conduction across small exposed structures, and always produces an eastward torque. But tangential YORP relies on structures at a preferred size scale, which shrinks to millimeters as the rotation rate approaches periods of a few hours. How the effects generated at these tiny scales are diluted by the mesoscale (meters to hectometers

  14. Study on Acceleration Mechanism of Liquid Alkali-free Accelerating Components%液体无碱速凝组分的速凝机理探讨

    Institute of Scientific and Technical Information of China (English)

    贺雄飞; 张迅

    2014-01-01

    The acceleration mechanism of liquid alkali-free accelerating components,including aluminum sulfate and aluminum fluoride,is discussed by testing on the setting time of cement paste mixed with aluminum sulfate and aluminum fluoride respectively,as well as by XRD analysis on the cement paste mixed with accelerating components after final setting,1-day hydration and 7-day hydration.The study results show that,due to the large amount of ettringite generated and the C3 S hydration caused by calcium ion reduction and hydration heat,the setting of the cement paste is accelerated when aluminum sulfate solution is mixed into the Portland cement;due to the C3 AH6 generated,the setting of the cement paste is accelerated by aluminum fluoride solution;the aluminum ion in the aluminum fluoride solution accelerates the hydration of the cement paste;the fluoride ion in the aluminum fluoride solution retards the setting of the cement paste.The paper can provide a theoretical basis for developing and promoting the application of high-performance liquid alkali-free accelerator.%通过测试单独掺入液体无碱速凝组分硫酸铝和氟化铝后水泥浆的凝结时间以及对掺速凝组分后达到终凝、水化1d及水化7 d 的水泥浆体进行XRD图谱分析,深入探讨液体无碱速凝剂组分硫酸铝和氟化铝对水泥的速凝机理。试验结果表明:硅酸盐水泥中掺入硫酸铝溶液因生成大量的钙矾石,同时因消耗大量的钙离子及水化热的作用促进C3 S的水化作用导致浆体快速凝结;氟化铝溶液主要通过形成C3 AH6而导致水泥浆体速凝,氟化铝溶液中铝离子对水泥水化起速凝作用,而氟离子起缓凝作用。

  15. Material studies in the frame of CLIC Accelerating structures production conducted within the Mechanics program together with Metso Oy

    CERN Document Server

    Nurminen, Janne

    2012-01-01

    MeChanICs (Marie Curie Linking Industry to CERN) is an Industry to Academia Partnership and Pathways (IAPP) platform for precision manufacturing knowledge exchange bringing together five Finnish manufacturing companies with Helsinki Insitute of Physics (HIP) and CERN. The scientific objective of MeChanICs project is to contribute to the manufacturing RTD of CLIC enabling technologies. The focus is on the design, materials, machining, brazing and assembly of A CLIC accelerating structure. This study deals with the materials work package of the program and wants to explore the following items: 1) producing copper accelerating structures for CLIC from raw copper powder by near net shape hot isostatic pressing (HIP). 2) The feasibility to use HIP diffusion bonding of the accelerator structures as a function of surface quality and applied temperature and pressure. 3) Brazing for CLIC AS auxiliary systems, like water cooling or damping manifolds, to the disc stack by coating one of the brazing partners with an enab...

  16. One DOF mechanism for the mechanical harvest of vines in an arbor structure and the validation of the acceleration of grape berry harvesting

    Science.gov (United States)

    Penisi, Osvaldo; Bocca, José; Aguilar, Horacio; Bocca, Pedro

    2015-09-01

    In the mechanized harvest of vines, grape berries are detached through the vibration to the structure supporting the clusters. According to the kind of guide selected, the clusters require one or two vibration directions in the structure. For guiding in parral structures, vibration is necessary in two directions or planes: One perpendicular to the other. The guide branches producing the clusters develop in these planes, and the guiding is called H-guiding. Mechanism theory indicates that a mechanism has as many degrees of freedom as its actuators, and an actuator is needed to achieve a certain vibration. Having the smallest number of possible actuators is beneficial in reducing moving parts and achieving more compact and easily controllable mechanisms. In this case, a single degree-of-freedom mechanism is proposed. It is capable of generating vibrations on two planes: One perpendicular to the other. This mechanism is the sum of two link mechanisms on perpendicular planes with a common outlet located at the output rod of the mechanism where the actuator is found. As the distance between the soil and the elements containing the clusters is not constant, a system has been designed to measure the accelerations at the bars and the rocker to validate the acceleration values that detach the grape berries in a prototype in a lab experiment, to ensure that the acceleration needed for pulling the grape berries are produced at any contact point of the bar.

  17. From laser particle acceleration to the synthesis of extremely neutron rich isotopes via the novel fission-fusion mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Thirolf, P. G., E-mail: Peter.Thirolf@lmu.de [Ludwig-Maximilians-Universität München, Am Coulombwall 1, Garching (Germany)

    2015-02-24

    High-power, short pulse lasers have emerged in the last decade as attractive tools for accelerating charged particles (electrons, ions) to high energies over mm-scale acceleration lengths, thus promising to rival conventional acceleration techniques in the years ahead. In the first part of the article, the principles of laser-plasma interaction as well as the techniques and the current status of the acceleration of electron and ion beams will be briefly introduced. In particular with the upcoming next generation of multi-PW class laser systems, such as the one under construction for the ELI-Nuclear Physics project in Bucharest (ELI-NP), very efficient acceleration mechanisms for brilliant ion beams like radiation pressure acceleration (RPA) come into reach. Here, ultra-dense ion beams reaching solid-state density can be accelerated from thin target foils, exceeding the density of conventionally accelerated ion beams by about 14 orders of magnitude. This unique property of laser-accelerated ion beams can be exploited to explore the scenario of a new reaction mechanism called ‘fission-fusion’, which will be introduced in the second part of the article. Accelerating fissile species (e.g. {sup 232}Th) towards a second layer of the same material will lead to fission both of the beam-like and target-like particles. Due to the close to solid-state density of the accelerated ion bunches, fusion may occur between neutron-rich (light) fission products. This may open an access path towards extremely neutron-rich nuclides in the vicinity of the N=126 waiting point of the astrophysical r process. ‘Waiting points’ at closed nucleon shells play a crucial role in controlling the reaction rates. However, since most of the pathway of heavy-element formation via the rapid-neutron capture process (r-process) runs in ‘terra incognita’ of the nuclear landscape, in particular the waiting point at N=126 is yet unexplored and will remain largely inaccessible to conventional

  18. IPS observations of the solar wind velocity and the acceleration mechanism

    Science.gov (United States)

    Ofman, L.; Davila, J. M.; Coles, W. A.; Grall, R. R.; Klinglesmith, M. T.

    1997-01-01

    Coronal holes are well know sources of high speed solar wind, however, the exact acceleration mechanism of the wind is still unknown. Interplanetary scintillation (IPS) observations indicate that the fast solar wind reaches an average velocity of 800 km s(exp -1) within several solar radii with large velocity fluctuations. However, the origin of the IPS velocity spread below 10 solar radii is unclear. A previously developed coronal home model with a more realistic initial state is applied, and time-dependent, nonlinear, resistive 2.5-DMHD equations are numerically solved. It is found that nonlinear solitary-like waves with a supersonic phase speed are generated in coronal holes by torisonal Alfven waves in the radial flow velocity. The outward propagating nonlinear waves are similar in properties to sound solitons. When these waves are present, the solar wind speed and density fluctuate considerably on a time scale of an hour and on spatial scales of several solar radii in addition to the Alfvenic fluctuations. This is in qualitative agreement with the IPS velocity observations beyond 10 solar radii.

  19. Prediction of strong acceleration motion depended on focal mechanism; Shingen mechanism wo koryoshita jishindo yosoku ni tsuite

    Energy Technology Data Exchange (ETDEWEB)

    Kaneda, Y.; Ejiri, J. [Obayashi Corp., Tokyo (Japan)

    1996-10-01

    This paper describes simulation results of strong acceleration motion with varying uncertain fault parameters mainly for a fault model of Hyogo-ken Nanbu earthquake. For the analysis, based on the fault parameters, the strong acceleration motion was simulated using the radiation patterns and the breaking time difference of composite faults as parameters. A statistic waveform composition method was used for the simulation. For the theoretical radiation patterns, directivity was emphasized which depended on the strike of faults, and the maximum acceleration was more than 220 gal. While, for the homogeneous radiation patterns, the maximum accelerations were isotopically distributed around the fault as a center. For variations in the maximum acceleration and the predominant frequency due to the breaking time difference of three faults, the response spectral value of maximum/minimum was about 1.7 times. From the viewpoint of seismic disaster prevention, underground structures including potential faults and non-arranging properties can be grasped using this simulation. Significance of the prediction of strong acceleration motion was also provided through this simulation using uncertain factors, such as breaking time of composite faults, as parameters. 4 refs., 4 figs., 1 tab.

  20. Mechanisms of blood pressure regulation that differ in men repeatedly exposed to high-G acceleration

    Science.gov (United States)

    Convertino, V. A.

    2001-01-01

    The purpose of this study was to test the hypothesis that repeated exposure to high acceleration (G) would be associated with enhanced functions of specific mechanisms of blood pressure regulation. We measured heart rate (HR), stroke volume (SV), cardiac output (), mean arterial blood pressure, central venous pressure, forearm and leg vascular resistance, catecholamines, and changes in leg volume (%DeltaLV) during various protocols of lower body negative pressure (LBNP), carotid stimulation, and infusions of adrenoreceptor agonists in 10 males after three training sessions on different days over a period of 5-7 days using a human centrifuge (G trained). These responses were compared with the same measurements in 10 males who were matched for height, weight, and fitness but did not undergo G training (controls). Compared with the control group, G-trained subjects demonstrated greater R-R interval response to equal carotid baroreceptor stimulation (7.3 +/- 1.2 vs. 3.9 +/- 0.4 ms/mmHg, P = 0.02), less vasoconstriction to equal low-pressure baroreceptor stimulation (-1.4 +/- 0.2 vs. -2.6 +/- 0.3 U/mmHg, P = 0.01), and higher HR (-1.2 +/- 0.2 vs. -0.5 +/- 0.1 beats. min(-1). mmHg(-1), P = 0.01) and alpha-adrenoreceptor response (32.8 +/- 3.4 vs. 19.5 +/- 4.7 U/mmHg, P = 0.04) to equal dose of phenylephrine. During graded LBNP, G-trained subjects had less decline in and SV, %DeltaLV, and elevation in thoracic impedance. G-trained subjects also had greater total blood (6,497 +/- 496 vs. 5,438 +/- 228 ml, P = 0.07) and erythrocyte (3,110 +/- 364 vs. 2,310 +/- 96 ml, P = 0.06) volumes. These results support the hypothesis that exposure to repeated high G is associated with increased capacities of mechanisms that underlie blood pressure regulation.

  1. Mechanical engineering and design criteria for the Magnetically Insulated Transmission Experiment Accelerator

    International Nuclear Information System (INIS)

    A single-unit electron beam accelerator was designed, fabricated, and assembled in Sandia's Technical Area V to conduct magnetically insulated transmission experiments. Results of these experiments will be utilized in the future design of larger, more complex accelerators. This design makes optimum use of existing facilities and equipment. When designing new components, possible future applications were considered as well as compatibility with existing facilities and hardware

  2. Evaluation of seismic acceleration responses of base-isolated and nonisolated structures varying with mechanical characteristics of foundations

    Energy Technology Data Exchange (ETDEWEB)

    You, Bong; Lee, Jae Han; Ku, Kyung Hoi [Korea Atomic Energy Research Institute, Daeduk (Korea, Republic of)

    1996-05-01

    The evaluation of acceleration responses of isolated and nonisolated structures according to mechanical features of soils is important. The kinds of soils taken in analyses are soft, medium and hard rocks, and a fixed base condition is also taken for the comparison. The horizontal isolation frequency used is 0.5 Hz. The time history analyses of reference power plant using 1940 El Centro horizontal (NS) and vertical earthquakes are performed to investigate the seismic responses varying with soil characteristics for isolated and nonisolated structures. The horizontal acceleration responses of the horizontal isolated-structures show almost similar values irrespective of the various kinds of soils and are largely decreased in the frequency ranges above 2 hz. The vertical natural frequency, 21Hz of high damping rubber bearing does not affect the vertical acceleration responses in case of soft rock, but largely affects in hard rock condition. For nonisolated structures, the acceleration responses are decreased in both horizontal and vertical directions by taking into account the soils in the analysis model. The extent of reduction of acceleration responses is larger in vertical direction than in horizontal one, as the stiffness of rock becomes softer. 8 tabs., 21 figs., 8 refs. (Author) .new.

  3. Mechanism of poly(acrylic acid) acceleration of antithrombin inhibition of thrombin: implications for the design of novel heparin mimics.

    Science.gov (United States)

    Monien, Bernhard H; Cheang, Kai I; Desai, Umesh R

    2005-08-11

    The bridging mechanism of antithrombin inhibition of thrombin is a dominant mechanism contributing a massive approximately 2500-fold acceleration in the reaction rate and is also a key reason for the clinical usage of heparin. Our recent study of the antithrombin-activating properties of a carboxylic acid-based polymer, poly(acrylic acid) (PAA), demonstrated a surprisingly high acceleration in thrombin inhibition (Monien, B. H.; Desai, U. R. J. Med. Chem. 2005, 48, 1269). To better understand this interesting phenomenon, we have studied the mechanism of PAA-dependent acceleration in antithrombin inhibition of thrombin. Competitive binding studies with low-affinity heparin and a heparin tetrasaccharide suggest that PAA binds antithrombin in both the pentasaccharide- and the extended heparin-binding sites, and these results are corroborated by molecular modeling. The salt-dependence of the K(D) of the PAA-antithrombin interaction shows the formation of five ionic interactions. In contrast, the contribution of nonionic forces is miniscule, resulting in an interaction that is significantly weaker than that observed for heparins. A bell-shaped profile of the observed rate constant for antithrombin inhibition of thrombin as a function of PAA concentration was observed, suggesting that inhibition proceeds through the "bridging" mechanism. The knowledge gained in this mechanistic study highlights important rules for the rational design of orally available heparin mimics. PMID:16078853

  4. Mangiferin, a natural xanthone, accelerates gastrointestinal transit in mice involving cholinergic mechanism

    Institute of Scientific and Technical Information of China (English)

    Talita Cavalcante Morais; Synara Cavalcante Lopes; Karine Maria Martins Bezerra Carvalho; Bruno Rodrigues Arruda; Francisco Thiago Correia de Souza; Maria Teresa Salles Trevisan; Vietla Satyanarayana Rao; Flávia Almeida Santos

    2012-01-01

    AIM:To investigate the effects of mangiferin on gastrointestinal transit (GIT) in normal and constipated mice,together with the possible mechanism.METHODS:Intragastrically-administered charcoal meal was used to measure GIT in overnight starved Swiss mice.In the first experiments,mangiferin (3 mg/kg,10mg/kg,30 mg/kg,and 100 mg/kg,po) or tegaserod (1mg/kg,ip) were administered 30 min before the charcoal meal to study their effects on normal transit.In the second series,mangiferin (30 mg/kg) was tested on delayed GIT induced by several different pharmacological agonists (morphine,clonidine,capsaicin) or antagonists (ondansetron,verapamil,and atropine) whereas in the third series,mangiferin (30 mg/kg,100mg/kg and 300 mg/kg) or tegaserod (1 mg/kg) were tested on 6 h fecal pellets outputted by freely fed mice.The ratio of wet to dry weight was calculated and used as a marker of fecal water content.RESULTS:Mangiferin administered orally significantly (P < 0.05) accelerated GIT at 30 mg/kg and 100 mg/kg (89%and 93%,respectively),similarly to 5-hydroxytryptamine4 (5-HT4) agonist tegaserod (81%) when compared to vehicle-treated control (63%).Co-administered mangiferin (30 mg/kg) totally reversed the inhibitory effect of opioid agonist morphine,5-HT3-receptor antagonist ondansetron and transient receptor potential vanilloid-1 receptor agonist capsaicin on GIT,but only to a partial extent with the GIT-delay induced by α2-adrenoceptor agonist clonidine,and calcium antagonist verapamil.However,co-administered atropine completely blocked the stimulant effect of mangiferin on GIT,suggesting the involvement of muscarinic acetylcholine receptor activation.Although mangiferin significantly enhanced the 6 h fecal output at higher doses (245.5 ± 10.43 mg vs 161.9 ± 10.82 mg and 227.1 ± 20.11 mg vs 161.9 ±10.82 mg of vehicle-treated control,at 30 and 100 mg/kg,P < 0.05,respectively),the effect of tegaserod was more potent (297.4 ± 7.42 mg vs 161.9 ± 10.82 mg of

  5. Ergonomic assessment of brake and accelerator mechanisms of MF285 and MF399 tractors using electromyography method

    Directory of Open Access Journals (Sweden)

    A Nikkhah

    2016-04-01

    Full Text Available Introduction: Too many people are working in the agricultural sector and therefore, pay more attention to the safety and health at work in the agricultural sector is important. This issue is more important in developing industrial countries where the level of the ergonomic working condition is less than that of developed countries. Attention to ergonomic condition of agricultural machinery drivers is one of the goals of agricultural mechanization. Therefore, in this study the ergonomic conditions of brake and accelerator mechanisms for MF285 and MF399 tractor's drivers were investigated using a new method. Materials and Methods: 25 people were selected for experiment. The electrical activity of Medialis gastrocnemius, Lateralis gastrocnemius, Vastus medialis, Vastus lateralis, Quadratus Lumborum and Trapezius muscles of drivers before and during pressing the pedal and after rest time were recorded using Biovision device. Measurements were performed for each person on each muscle 30 seconds before pressing the pedal, 60 seconds after pressing the pedal and after 60 seconds of rest. For all drivers, the muscles on the right side (brake and accelerator side have been selected and tested. The measurements were performed in compliance with appropriate time intervals between the measurements. Results and Discussion: Ergonomic assessment of brake pedal: The results showed that the RMS electrical activity of muscles of Vastus medialis and Medial gastrocnemius, during 60 seconds braking were 2.47 and 1.97. So, Vastus medialis and Medial gastrocnemius had the highest stress during pressing the MF399 tractor's brake pedal. Moreover, the Medial gastrocnemius and Lateral gastrocnemius with RMS electrical activity ratio of 2.47 and 1.74 had the highest RMS electrical activity ratio respectively, during 60 seconds braking compared to before braking of MF285 tractor. The comparison of results showed that the Vastus medialis and Trapezius had the higher stress

  6. Effect of accelerated aging of MSWI bottom ash on the leaching mechanisms of copper and molybdenum

    NARCIS (Netherlands)

    Dijkstra, J.J.; Zomeren, van A.; Meeussen, J.C.L.; Comans, R.N.J.

    2006-01-01

    The effect of accelerated aging of Municipal Solid Waste Incinerator (MSWI) bottom ash on the leaching of Cu and Mo was studied using a "multisurface" modeling approach, based on surface complexation to iron/aluminum (hydr) oxides, mineral dissolution/precipitation, and metal complexation by humic s

  7. Mechanical Design of a High Energy Beam Absorber for the Advanced Superconducting Test Accelerator (ASTA) at Fermilab

    CERN Document Server

    Baffes, C; Leibfritz, J; Oplt, S; Rakhno, I

    2013-01-01

    A high energy beam absorber has been built for the Advanced Superconducting Test Accelerator (ASTA) at Fermilab. In the facility's initial configuration, an electron beam will be accelerated through 3 TTF-type or ILC-type RF cryomodules to an energy of 750MeV. The electron beam will be directed to one of multiple downstream experimental and diagnostic beam lines and then deposited in one of two beam absorbers. The facility is designed to accommodate up to 6 cryomodules, which would produce a 75kW beam at 1.5GeV; this is the driving design condition for the beam absorbers. The beam absorbers consist of water-cooled graphite, aluminum and copper layers contained in a Helium-filled enclosure. This paper describes the mechanical implementation of the beam absorbers, with a focus on thermal design and analysis. In addition, the potential for radiation-induced degradation of the graphite is discussed.

  8. Mechanism and Optimal Application of Chemical Additives for Accelerating Early Strength of Lime-flyash Stabilized Soils

    Institute of Scientific and Technical Information of China (English)

    JIANG Zengguo; ZHAO Yuan

    2005-01-01

    To accelerate the early strength of lime-flyash stabilized soil for extending its further uses in highway and shortening highway construction time, five kinds of chemical additives were chosen on the basis of mechanism analysis of accelerating early strength in highway as a semi-rigid base material, and a series of experiments about the effect of different kinds of additives and quantity on the early strength of the stabilized soil were tested. The results show that chemical additives can efficiently improve the early strength of lime-flyash stabilized soil both the 7 d and 28d, and the optimum quantity for above chemical additive is 1.5%-2.5% approximately.Some suggestions for the practical construction were also proposed.

  9. Mechanical Design of a High Energy Beam Absorber for the Advanced Superconducting Test Accelerator (ASTA) at Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    Baffes, C.; Church, M.; Leibfritz, J.; Oplt, S.; Rakhno, I.; /Fermilab

    2012-05-10

    A high energy beam absorber has been built for the Advanced Superconducting Test Accelerator (ASTA) at Fermilab. In the facility's initial configuration, an electron beam will be accelerated through 3 TTF-type or ILC-type SRF cryomodules to an energy of 750MeV. The electron beam will be directed to one of multiple downstream experimental and diagnostic beam lines and then deposited in one of two beam absorbers. The facility is designed to accommodate up to 6 cryomodules, which would produce a 75kW beam at 1.5GeV; this is the driving design condition for the beam absorbers. The beam absorbers consist of water-cooled graphite, aluminum and copper layers contained in a helium-filled enclosure. This paper describes the mechanical implementation of the beam absorbers, with a focus on thermal design and analysis. The potential for radiation-induced degradation of the graphite is discussed.

  10. Sprint acceleration mechanics: the major role of hamstrings in horizontal force production

    Directory of Open Access Journals (Sweden)

    Jean-Benoit eMORIN

    2015-12-01

    Full Text Available Recent literature supports the importance of horizontal ground reaction force (GRF production for sprint acceleration performance. Modeling and clinical studies have shown that the hip extensors are very likely contributors to sprint acceleration performance. We experimentally tested the role of the hip extensors in horizontal GRF production during short, maximal, treadmill sprint accelerations. Torque capabilities of the knee and hip extensors and flexors were assessed using an isokinetic dynamometer in 14 males familiar with sprint running. Then, during 6-s sprints on an instrumented motorized treadmill, horizontal and vertical GRF were synchronized with electromyographic (EMG activity of the vastus lateralis, rectus femoris, biceps femoris and gluteus maximus averaged over the first half of support, entire support, entire swing and end-of-swing phases. No significant correlations were found between isokinetic or EMG variables and horizontal GRF. Multiple linear regression analysis showed a significant relationship (P = 0.024 between horizontal GRF and the combination of biceps femoris EMG activity during the end of the swing and the knee flexors eccentric peak torque. In conclusion, subjects who produced the greatest amount of horizontal force were both able to highly activate their hamstring muscles just before ground contact and present high eccentric hamstring peak torque capability.

  11. Laser-driven proton beams: Acceleration mechanism, beam optimization, and radiographic applications

    Energy Technology Data Exchange (ETDEWEB)

    Borghesi, M.; Romagnani, L.; Kar, S.; Wilson, P.A. [School of Mathematics and Physics, The Queen' s University of Belfast (United Kingdom); Cecchetti, C.A. [School of Mathematics and Physics, The Queen' s University of Belfast (United Kingdom); Also with the Intense Laser Irradiation Laboratory, IPCF-CNR, Pisa (Italy); Toncian, T.; Pipahl, A.; Amin, M.; Jung, R.; Osterholz, J.; Willi, O. [Institute for Laser and Plasma Physics, Heinrich Heine University, Dusseldorf (Germany); Fuchs, J.; Audebert, P.; Brambrink, E. [Laboratoire pour l' Utilisation des Lasers Intenses LULI, UMR 7605 CNRS-CEA-Ecole Polytechnique, 91 - Palaiseau (France); Antici, P. [Laboratoire pour l' Utilisation des Lasers Intenses LULI, UMR 7605 CNRS CEA Ecole Polytechnique, 91 - Palaiseau (France); Frascati National Laboratories INFN, Frascati (Italy); Nazarov, W. [School of Chemistry, University of St. Andrews, St. Andrews (United Kingdom); Clarke, R.J.; Notley, M.; Neely, D. [Central Laser Facility, STFC Rutherford Appleton Laboratory, OX Didcot (United Kingdom); Mora, P.; Grismayer, T. [Centre de Physique Theorique, Ecole Polytechnique, CNRS, 91 - Palaiseau (France); Schurtz, G. [Centre d' Etudes des Lasers Intenses et Applications, UMR 5107 University Bordeaux I-CNRS-CEA, 33 - Talence (France); Schiavi, A. [Dipartimento di Energetica, Universita -La Sapienza-, Rome (Italy); Sentoku, Y.; D' Humieres, E. [Physics Department, MS 220, University of Nevada, Reno, NV (United States)

    2008-08-15

    This paper reviews recent experimental activity in the area of optimization, control, and application of laser-accelerated proton beams, carried out at the Rutherford Appleton Laboratory and the Laboratoire pour l'Utilisation des Lasers Intenses 100 TW facility in France. In particular, experiments have investigated the role of the scale length at the rear of the plasma in reducing target-normal-sheath-acceleration acceleration efficiency. Results match with recent theoretical predictions and provide information in view of the feasibility of proton fast-ignition applications. Experiments aiming to control the divergence of the proton beams have investigated the use of a laser-triggered micro-lens, which employs laser-driven transient electric fields in cylindrical geometry, enabling to focus the emitted protons and select monochromatic beamlets; out of the broad spectrum beam. This approach could be advantageous in view of a variety of applications. The use of laser-driven protons as a particle probe for transient field detection has been developed and applied to a number of experimental conditions. Recent work in this area has focused on the detection of large-scale self-generated magnetic fields in laser-produced plasmas and the investigation of fields associated to the propagation of relativistic electron both on the surface and in the bulk of targets irradiated by high-power laser pulses. (authors)

  12. Coupled mechanical-electrostatic FE-BE analysis with FMM acceleration

    OpenAIRE

    Sabariego, Ruth,; Gyselinck, J.; Dular, P.; De Coster, Jeroen; Henrotte, François; HAMEYER, Kay

    2004-01-01

    This paper deals with the coupled mechanical-electrostatic analysis of a shunt capacitive MEMS switch. The mechanical and electrostatic parts of the prob- lem are modelled by the FE method and BE method, respectively. The fast multipole method is applied to reduce the storage requirements and the computational cost of the BE electrostatic model. An adaptive truncation expansion of the 3D Laplace Green function is employed. The strong interaction between the mechanical and electrostatic system...

  13. Mechanical properties of electrospun PCL scaffold under in vitro and accelerated degradation conditions

    DEFF Research Database (Denmark)

    Løvdal, Alexandra Liv Vest; Vange, Jakob; Nielsen, Lene Feldskov;

    2014-01-01

    Within recent years, researchers have looked into using polycaprolactone (PCL) as a synthetic biodegradable scaffold for tissue engineering purposes. This study investigated the mechanical properties of an electrospun PCL, while being exposed to physiological fluids at 37C (in vitro conditions...... not deteriorate the mechanical properties of PCL after 16 weeks. The viability of the cells decreased over time, however, without influencing the mechanical properties of the scaffold. A relation between reduction in molecular weight and the mechanical properties of electrospun PCL was seen between 2–29 days...

  14. Accelerator and Technical Sector Seminar: Mechanical stabilization and positioning of CLIC quadrupoles with sub-nanometre resolution

    CERN Multimedia

    2011-01-01

    Thursday 24 November 2010 Accelerator and Technical Sector Seminar at 14:15  -  BE Auditorium, bldg. 6 (Meyrin) – please note unusual place Mechanical stabilization and positioning of CLIC quadrupoles with sub-nanometre resolution Stef Janssens /EN-MME Abstract: To reach the required luminosity at the CLIC interaction point, about 4000 quadrupoles are needed to obtain a vertical beam size of 1 nm at the interaction point. The mechanical jitter of the quadrupole magnets will result in an emittance growth. An active vibration isolation system is required to reduce vibrations from the ground and from external forces to about 1.5 nm integrated root mean square (r.m.s.) vertical displacement at 1 Hz. A short overview of vibration damping and isolation strategies will be presented as well as a comparison of existing systems. The unprecedented resolution requirements and the instruments enabling these measurements will be discussed. The vibration sources from which the magnets need to...

  15. The effect of artificial accelerated weathering on the mechanical properties of maxillofacial polymers PDMS and CPE

    Energy Technology Data Exchange (ETDEWEB)

    Eleni, P N; Krokida, M K [Department of Chemical Engineering, National Technical University of Athens, Zografou, Campus, 15780 Athens (Greece); Polyzois, G L [Division of Removable Prosthodontics, University of Athens, Dental School, 2 Thivon Street, 11527 Athens (Greece)

    2009-06-15

    The effect of UVA-UVB irradiation on the mechanical properties of three different industrial types of polydimethylsiloxane and chlorinated polyethylene samples, used in maxillofacial prostheses, was investigated in this study. Mechanical properties and thermal analysis are commonly used to determine the structural changes and mechanical strength. An aging chamber was used in order to simulate the solar radiation and assess natural aging. Compression and tensile tests were conducted on a Zwick testing machine. Durometer Shore A hardness measurements were carried out in a CV digital Shore A durometer according to ASTM D 2240. Glass transition temperature was evaluated with a differential scanning calorimeter. Simple mathematical models were developed to correlate the measured properties with irradiation time. The effect of UVA-UVB irradiation on compressive behavior affected model parameters. Significant deterioration seems to occur due to irradiation in samples.

  16. RAGE mediates accelerated diabetic vein graft atherosclerosis induced by combined mechanical stress and AGEs via synergistic ERK activation.

    Directory of Open Access Journals (Sweden)

    Yuhuang Li

    Full Text Available AIMS/HYPOTHESIS: Diabetes with hypertension rapidly accelerates vascular disease, but the underlying mechanism remains unclear. We evaluated the hypothesis that the receptor of advanced glycation end products (RAGE might mediate combined signals initiated by diabetes-related AGEs and hypertension-induced mechanical stress as a common molecular sensor. METHODS: In vivo surgical vein grafts created by grafting vena cava segments from C57BL/6J mice into the common carotid arteries of streptozotocin (STZ-treated and untreated isogenic mice for 4 and 8 weeks were analyzed using morphometric and immunohistochemical techniques. In vitro quiescent mouse vascular smooth muscle cells (VSMCs with either knockdown or overexpression of RAGE were subjected to cyclic stretching with or without AGEs. Extracellular signal-regulated kinase (ERK phosphorylation and Ki-67 expression were investigated. RESULTS: Significant increases in neointimal formation, AGE deposition, Ki-67 expression, and RAGE were observed in the vein grafts of STZ-induced diabetic mice. The highest levels of ERK phosphorylation and Ki-67 expression in VSMCs were induced by simultaneous stretch stress and AGE exposure. The synergistic activation of ERKs and Ki-67 in VSMCs was significantly inhibited by siRNA-RAGE treatment and enhanced by over-expression of RAGE. CONCLUSION: RAGE may mediate synergistically increased ERK activation and VSMC proliferation induced by mechanical stretching with and without AGEs. It may serve as a common molecular bridge between the two, accelerating vascular remodeling. This study provides potential drug targets and novel therapeutic strategies for the treatment of vascular diseases resulting from diabetes with hypertension.

  17. Neural Network Models of Simple Mechanical Systems Illustrating the Feasibility of Accelerated Life Testing

    Science.gov (United States)

    Fusaro, Robert L.; Jones, Steven P.; Jansen, Ralph

    1996-01-01

    A complete evaluation of the tribological characteristics of a given material/mechanical system is a time-consuming operation since the friction and wear process is extremely systems sensitive. As a result, experimental designs (i.e., Latin Square, Taguchi) have been implemented in an attempt to not only reduce the total number of experimental combinations needed to fully characterize a material/mechanical system, but also to acquire life data for a system without having to perform an actual life test. Unfortunately, these experimental designs still require a great deal of experimental testing and the output does not always produce meaningful information. In order to further reduce the amount of experimental testing required, this study employs a computer neural network model to investigate different material/mechanical systems. The work focuses on the modeling of the wear behavior, while showing the feasibility of using neural networks to predict life data. The model is capable of defining which input variables will influence the tribological behavior of the particular material/mechanical system being studied based on the specifications of the overall system.

  18. THE MECHANICAL AND SHIELDING DESIGN OF A PORTABLE SPECTROMETER AND BEAM DUMP ASSEMBLY AT BNLS ACCELERATOR TEST FACILITY.

    Energy Technology Data Exchange (ETDEWEB)

    HU,J.P.; CASEY,W.R.; HARDER,D.A.; PJEROV,S.; RAKOWSKY,G.; SKARITKA,J.R.

    2002-09-05

    A portable assembly containing a vertical-bend dipole magnet has been designed and installed immediately down-beam of the Compton electron-laser interaction chamber on beamline 1 of the Accelerator Test Facility (ATF) at Brookhaven National Laboratory (BNL). The water-cooled magnet designed with field strength of up to 0.7 Tesla will be used as a spectrometer in the Thompson scattering and vacuum acceleration experiments, where field-dependent electron scattering, beam focusing and energy spread will be analyzed. This magnet will deflect the ATF's 60 MeV electron-beam 90{sup o} downward, as a vertical beam dump for the Compton scattering experiment. The dipole magnet assembly is portable, and can be relocated to other beamlines at the ATF or other accelerator facilities to be used as a spectrometer or a beam dump. The mechanical and shielding calculations are presented in this paper. The structural rigidity and stability of the assembly were studied. A square lead shield surrounding the assembly's Faraday Cup was designed to attenuate the radiation emerging from the 1 inch-copper beam stop. All photons produced were assumed to be sufficiently energetic to generate photoneutrons. A safety evaluation of groundwater tritium contamination due to the thermal neutron capturing by the deuterium in water was performed, using updated Monte Carlo neutron-photon coupled transport code (MCNP). High-energy neutron spallation, which is a potential source to directly generate radioactive tritium and sodium-22 in soil, was conservatively assessed in verifying personal and environmental safety.

  19. The erosion of the beaches on the coast of Alicante: Study of the mechanisms of weathering by accelerated laboratory tests.

    Science.gov (United States)

    López, I; López, M; Aragonés, L; García-Barba, J; López, M P; Sánchez, I

    2016-10-01

    One of the main problems that coasts around the world present, is the regression and erosion of beaches. However, the factors involved in these processes are unclear. In this study, the influence of sediment erosion on beach regression has been analysed. In order to do that, a three-step investigation has been carried out. Firstly, coastline variations of four Spanish beaches have been analysed. Secondly, a study on sediment position along the beach profile has been developed. Finally, the process that beach sediments undergo along the surf zone when they are hit by the incident waves has been simulated by an accelerated particle weathering test. Samples of sand and shells were subjected to this accelerated particle weathering test. Results were supplemented with those from carbonate content test, XRD, SEM and granulometric analysis. Results shows a cross-shore classification of sediments along the beach profile in which finer particles move beyond offshore limit. Besides, it was observed that sediment erosion process is divided into three sages: i) particles wear due to crashes ii) dissolution of the carbonate fraction, and iii) breakage and separation of mineral and carbonate parts of particles. All these processes lead to a reduction of particle size. The mechanism responsible of beach erosion would consist of multiples and continuous particle location exchanges along the beach profile as a consequence of grain-size decrease due to erosion.

  20. The erosion of the beaches on the coast of Alicante: Study of the mechanisms of weathering by accelerated laboratory tests.

    Science.gov (United States)

    López, I; López, M; Aragonés, L; García-Barba, J; López, M P; Sánchez, I

    2016-10-01

    One of the main problems that coasts around the world present, is the regression and erosion of beaches. However, the factors involved in these processes are unclear. In this study, the influence of sediment erosion on beach regression has been analysed. In order to do that, a three-step investigation has been carried out. Firstly, coastline variations of four Spanish beaches have been analysed. Secondly, a study on sediment position along the beach profile has been developed. Finally, the process that beach sediments undergo along the surf zone when they are hit by the incident waves has been simulated by an accelerated particle weathering test. Samples of sand and shells were subjected to this accelerated particle weathering test. Results were supplemented with those from carbonate content test, XRD, SEM and granulometric analysis. Results shows a cross-shore classification of sediments along the beach profile in which finer particles move beyond offshore limit. Besides, it was observed that sediment erosion process is divided into three sages: i) particles wear due to crashes ii) dissolution of the carbonate fraction, and iii) breakage and separation of mineral and carbonate parts of particles. All these processes lead to a reduction of particle size. The mechanism responsible of beach erosion would consist of multiples and continuous particle location exchanges along the beach profile as a consequence of grain-size decrease due to erosion. PMID:27220096

  1. Mechanical properties as an indicator of interstitials in niobium for superconducting accelerator cavities

    International Nuclear Information System (INIS)

    A preliminary investigation was conducted into the feasibility of using simple mechanical properties experiments to evaluate interstitial impurity uptake from processing environments. Two types of tests were examined: tensile tests and complex modulus measurements using a dynamic mechanical analyzer (DMA). For the tensile tests, samples were cut from a single crystal of niobium, with the same orientation, and then prepared following different procedures. Significant differences were observed during tensile tests, with yielding strength and strain-to-failure clearly related to interstitial uptake. When the strain rate was reduced by an order of magnitude, the strain-to-failure was reduced by 18 % indicating that interstitial hydrogen is responsible for this behavior. For the complex modulus measurement, polycrystalline samples from different locations of two different ingots were examined at a frequency of 1.0 Hz while the temperature was increased at the rate of 1.0 °C per minute. Anaelastic peaks were found for C, N, and O in all samples, but the lower limit of the system did not allow for detection of a peak for H. It is concluded that mechanical properties could be developed as a measurement tool to guide the development of processing methods for producing reduced interstitial content material, but additional research, and uncertainty analysis, is required for these tools to be reliable in this application

  2. Mechanical properties as an indicator of interstitials in niobium for superconducting accelerator cavities

    Energy Technology Data Exchange (ETDEWEB)

    Ricker, R. E., E-mail: richard.ricker@nist.gov; Pitchure, D. J., E-mail: david.pitchure@nist.gov [Materials Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, US (United States); Myneni, G. R., E-mail: rao@jlab.org [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606, US (United States)

    2015-12-04

    A preliminary investigation was conducted into the feasibility of using simple mechanical properties experiments to evaluate interstitial impurity uptake from processing environments. Two types of tests were examined: tensile tests and complex modulus measurements using a dynamic mechanical analyzer (DMA). For the tensile tests, samples were cut from a single crystal of niobium, with the same orientation, and then prepared following different procedures. Significant differences were observed during tensile tests, with yielding strength and strain-to-failure clearly related to interstitial uptake. When the strain rate was reduced by an order of magnitude, the strain-to-failure was reduced by 18 % indicating that interstitial hydrogen is responsible for this behavior. For the complex modulus measurement, polycrystalline samples from different locations of two different ingots were examined at a frequency of 1.0 Hz while the temperature was increased at the rate of 1.0 °C per minute. Anaelastic peaks were found for C, N, and O in all samples, but the lower limit of the system did not allow for detection of a peak for H. It is concluded that mechanical properties could be developed as a measurement tool to guide the development of processing methods for producing reduced interstitial content material, but additional research, and uncertainty analysis, is required for these tools to be reliable in this application.

  3. Another Mechanism which Can Prevent Infinite Collision Energy via Black Hole as Particle Accelerators

    Science.gov (United States)

    Ding, Chikun; Lin, Siyuan; Li, Junfeng; Wang, Peng; Li, Qian; Zhang, Binqing

    2013-03-01

    It has recently been pointed out that infinite center of mass energies for the colliding particles can be attained when the black hole is exactly extremal and only at infinite time and on the horizon of the black hole. In this letter, we show that it cannot occur when the spacetime noncommutative effect is considered, i.e. the quantum effect of gravity is an other preventing mechanism. Additionally, the bigger of the black hole's mass is, the higher of center of mass energy that the particles obtain.

  4. Mechanical quality assurance using light field for linear accelerators with camera calibration.

    Science.gov (United States)

    Park, Kwangwoo; Choi, Wonhoon; Keum, Ki Chang; Lee, Ho; Yoon, Jeongmin; Lee, Chang Geol; Lee, Ik Jae; Cho, Jaeho

    2016-02-01

    Mechanical Quality Assurance (QA) is important to assure spatially precise delivery of external-beam radiation therapy. As an alternative to the conventional-film based method, we have developed a new tool for mechanical QA of LINACs which uses a light field rather than radiation. When light passes through the collimator, a shadow is projected onto a piece of translucent paper and the resulting image is captured by a digital camera via a mirror. With this method, we evaluated the position of the LINAC isocenter and the accuracy of the gantry, collimator, and couch rotation. We also evaluated the accuracy of the digital readouts of the gantry, collimator, and couch rotation. In addition, the treatment couch position indicator was tested. We performed camera calibration as an essential pre-requisite for quantitative measurements of the position of isocenter, the linear motion of the couch, and the rotation angles of the gantry and collimator. Camera calibration reduced the measurement error to submillimeter based on uncertainty in pixel size of the image, while, without calibration, the measurement error of up to 2 mm could occur for an object with a length of 5 cm.

  5. Calculation of mechanical stresses and deformations in superconducting magnets of the accelerating-storage complex

    International Nuclear Information System (INIS)

    To provide working capacity of superconducting magnets, mechanical stresses and deformations in the superconducting coil and tyre under conditions maximally approaching the practical ones are calculated. Calculations are carried out for the following processes: construction deformation under the effect of ponderomotive forces corresponding to the 50 kGs magnetic field in the centre; coil compression by a press; welding in points; magnet cooling till helium tempe-- rature. It is shown that the tyre thickness should be not less than 2.5 cm to prevent changes in the coil shape. The maximum press loading should be 3150 kg/cm2. The numerical values of deviations of coordinates of some boundary points of the coil from the optimum values at additional press compression are given

  6. Coupled Mechanical-Electrochemical-Thermal Modeling for Accelerated Design of EV Batteries; NREL (National Renewable Energy Laboratory)

    Energy Technology Data Exchange (ETDEWEB)

    Pesaran, Ahmad; Zhang, Chao; Kim, Gi-heon; Santhanagopalan, Shriram

    2015-06-10

    The physical and chemical phenomena occurring in a battery are many and complex and in many different scales. Without a better knowledge of the interplay among the multi-physics occurring across the varied scales, it is very challenging and time consuming to design long-lasting, high-performing, safe, affordable large battery systems, enabling electrification of the vehicles and modernization of the grid. The National Renewable Energy Laboratory, a U.S. Department of Energy laboratory, has been developing thermal and electrochemical models for cells and battery packs. Working with software producers, carmakers, and battery developers, computer-aided engineering tools have been developed that can accelerate the electrochemical and thermal design of batteries, reducing time to develop and optimize them and thus reducing the cost of the system. In the past couple of years, we initiated a project to model the mechanical response of batteries to stress, strain, fracture, deformation, puncture, and crush and then link them to electrochemical and thermal models to predict the response of a battery. This modeling is particularly important for understanding the physics and processes that happen in a battery during a crush-inducing vehicle crash. In this paper, we provide an overview of electrochemical-thermal-mechanical models for battery system understanding and designing.

  7. Effect of Accelerated Xenon Lamp Aging on the Mechanical Properties and Structure of Thermoplastic Polyurethane for Stratospheric Airship Envelope

    Institute of Scientific and Technical Information of China (English)

    LIU Yuyan; LIU Yuxi; LIU Shaozhu; TAN Huifeng

    2014-01-01

    This study aimed to investigate the effect of artificial weathering test on the photoaging behavior of TPU films. Changes in mechanical properties, morphology and chemical structures are studied by tensile test, scanning electron microscopy, atomic force microscopy, Fourier-transformed infrared, and X-ray photoelectron spectroscopy. The results show that the photoaging negatively affects the initial modulus and stress at break values of TPU films. The surface of the specimen that is exposed to irradiation becomes rough, and some visible micro-defects such as blisters and voids can be detected. The morphology of the fracture surfaces illustrates that irradiation reduces the plasticity but increases the brittleness of the TPU films. The chemical structure analyses of the accelerated aged films prove that chemical structural changes in TPU films occur. The irradiation may break the long molecular chains on the surface of the specimens and form the low-molecular weight oxygen-containing groups. The number of chain scissions increases with the increase in exposure time.

  8. Noncanonical Myo9b-RhoGAP Accelerates RhoA GTP Hydrolysis by a Dual-Arginine-Finger Mechanism.

    Science.gov (United States)

    Yi, Fengshuang; Kong, Ruirui; Ren, Jinqi; Zhu, Li; Lou, Jizhong; Wu, Jane Y; Feng, Wei

    2016-07-31

    The GTP hydrolysis activities of Rho GTPases are stimulated by GTPase-activating proteins (GAPs), which contain a RhoGAP domain equipped with a characteristic arginine finger and an auxiliary asparagine for catalysis. However, the auxiliary asparagine is missing in the RhoGAP domain of Myo9b (Myo9b-RhoGAP), a unique motorized RhoGAP that specifically targets RhoA for controlling cell motility. Here, we determined the structure of Myo9b-RhoGAP in complex with GDP-bound RhoA and magnesium fluoride. Unexpectedly, Myo9b-RhoGAP contains two arginine fingers at its catalytic site. The first arginine finger resembles the one within the canonical RhoGAP domains and inserts into the nucleotide-binding pocket of RhoA, whereas the second arginine finger anchors the Switch I loop of RhoA and interacts with the nucleotide, stabilizing the transition state of GTP hydrolysis and compensating for the lack of the asparagine. Mutating either of the two arginine fingers impaired the catalytic activity of Myo9b-RhoGAP and affected the Myo9b-mediated cell migration. Our data indicate that Myo9b-RhoGAP accelerates RhoA GTP hydrolysis by a previously unknown dual-arginine-finger mechanism, which may be shared by other noncanonical RhoGAP domains lacking the auxiliary asparagine. PMID:27363609

  9. A novel incoherent x-ray source using the inverse Compton scattering mechanism in a linear accelerator

    International Nuclear Information System (INIS)

    A classical theory to characterize inverse Compton scattering from a pulsed relativistic electron beam colliding head on with a high energy, pulsed, laser beam has been developed and is presented. Agreement between classical and quantum mechanical theories are demonstrated. Analytical expressions for the total and differential powers are shown. Numerical studies are based on the parameters of an existing linear accelerator and existing high energy ruby and CO2 lasers. The electron beam and photon beam profiles are pulsed along and gaussian perpendicular to the direction of motion. Numerical calculations show that the total power scattered from a single 30 MeV, 500 ps pulsed electron beam (3--10 nC) illuminated with a single 5 ns pulse of focused ruby or CO2 photons (10 J) can generate enough X-ray photons to be detected with a sensitive CsI x-ray detector. The scattered power is distributed in a vary narrow conical region in the back scattered direction. This distribution is shown and the properties of the windowless CsI x-ray detector are presented. The tunable property of this VUV/X-ray source is discussed. A comparison with other non-nuclear x-ray source are made

  10. Mechanisms underlying insulin deficiency-induced acceleration of β-amyloidosis in a mouse model of Alzheimer's disease.

    Directory of Open Access Journals (Sweden)

    Latha Devi

    Full Text Available Although evidence is accumulating that diabetes mellitus is an important risk factor for sporadic Alzheimer's disease (AD, the mechanisms by which defects in insulin signaling may lead to the acceleration of AD progression remain unclear. In this study, we applied streptozotocin (STZ to induce experimental diabetes in AD transgenic mice (5XFAD model and investigated how insulin deficiency affects the β-amyloidogenic processing of amyloid precursor protein (APP. Two and half months after 5XFAD mice were treated with STZ (90 mg/kg, i.p., once daily for two consecutive days, they showed significant reductions in brain insulin levels without changes in insulin receptor expression. Concentrations of cerebral amyloid-β peptides (Aβ40 and Aβ42 were significantly increased in STZ-treated 5XFAD mice as compared with vehicle-treated 5XFAD controls. Importantly, STZ-induced insulin deficiency upregulated levels of both β-site APP cleaving enzyme 1 (BACE1 and full-length APP in 5XFAD mouse brains, which was accompanied by dramatic elevations in the β-cleaved C-terminal fragment (C99. Interestingly, BACE1 mRNA levels were not affected, whereas phosphorylation of the translation initiation factor eIF2α, a mechanism proposed to mediate the post-transcriptional upregulation of BACE1, was significantly elevated in STZ-treated 5XFAD mice. Meanwhile, levels of GGA3, an adapter protein responsible for sorting BACE1 to lysosomal degradation, are indistinguishable between STZ- and vehicle-treated 5XFAD mice. Moreover, STZ treatments did not affect levels of Aβ-degrading enzymes such as neprilysin and insulin-degrading enzyme (IDE in 5XFAD brains. Taken together, our findings provide a mechanistic foundation for a link between diabetes and AD by demonstrating that insulin deficiency may change APP processing to favor β-amyloidogenesis via the translational upregulation of BACE1 in combination with elevations in its substrate, APP.

  11. Acceleration of dormant storage effects to address the reliability of silicon surface micromachined Micro-Electro-Mechanical Systems (MEMS).

    Energy Technology Data Exchange (ETDEWEB)

    Cox, James V.; Candelaria, Sam A.; Dugger, Michael Thomas; Duesterhaus, Michelle Ann; Tanner, Danelle Mary; Timpe, Shannon J.; Ohlhausen, James Anthony; Skousen, Troy J.; Jenkins, Mark W.; Jokiel, Bernhard, Jr.; Walraven, Jeremy Allen; Parson, Ted Blair

    2006-06-01

    Qualification of microsystems for weapon applications is critically dependent on our ability to build confidence in their performance, by predicting the evolution of their behavior over time in the stockpile. The objective of this work was to accelerate aging mechanisms operative in surface micromachined silicon microelectromechanical systems (MEMS) with contacting surfaces that are stored for many years prior to use, to determine the effects of aging on reliability, and relate those effects to changes in the behavior of interfaces. Hence the main focus was on 'dormant' storage effects on the reliability of devices having mechanical contacts, the first time they must move. A large number ({approx}1000) of modules containing prototype devices and diagnostic structures were packaged using the best available processes for simple electromechanical devices. The packaging processes evolved during the project to better protect surfaces from exposure to contaminants and water vapor. Packages were subjected to accelerated aging and stress tests to explore dormancy and operational environment effects on reliability and performance. Functional tests and quantitative measurements of adhesion and friction demonstrated that the main failure mechanism during dormant storage is change in adhesion and friction, precipitated by loss of the fluorinated monolayer applied after fabrication. The data indicate that damage to the monolayer can occur at water vapor concentrations as low as 500 ppm inside the package. The most common type of failure was attributed to surfaces that were in direct contact during aging. The application of quantitative methods for monolayer lubricant analysis showed that even though the coverage of vapor-deposited monolayers is generally very uniform, even on hidden surfaces, locations of intimate contact can be significantly depleted in initial concentration of lubricating molecules. These areas represent defects in the film prone to adsorption of

  12. The Influence of Irradiation and Accelerated Aging on the Mechanical and Tribological Properties of the Graphene Oxide/Ultra-High-Molecular-Weight Polyethylene Nanocomposites

    Directory of Open Access Journals (Sweden)

    Guodong Huang

    2016-01-01

    Full Text Available Graphene oxide/ultra-high-molecular-weight polyethylene (GO/UHMWPE nanocomposite is a potential and promising candidate for artificial joint applications. However, after irradiation and accelerated aging, the mechanical and tribological behaviors of the nanocomposites are still unclear and require further investigation. GO/UHMWPE nanocomposites were successfully fabricated using ultrasonication dispersion, ball-milling, and hot-pressing process. Then, the nanocomposites were irradiated by gamma ray at doses of 100 kGy. Finally, GO/UHMWPE nanocomposites underwent accelerated aging at 80°C for 21 days in air. The mechanical and tribological properties of GO/UHMWPE nanocomposites have been evaluated after irradiation and accelerated aging. The results indicated that the incorporation of GO could enhance the mechanical, wear, and antiscratch properties of UHMWPE. After irradiation, these properties could be further enhanced, compared to unirradiated ones. After accelerated aging, however, these properties have been significantly reduced when compared to unirradiated ones. Moreover, GO and irradiation can synergistically enhance these properties.

  13. Physical Mechanisms and Feedback Control of Beam Halo-Chaos for Accelerator-driven Radioactive-clean Nuclear Power Systems

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    High-current proton beams have attractive features for possible breakthrough applications, especially for accelerator-driven radioactive-clean nuclear power systems (ADS), which make nuclear energy systems safer, cleaner, cheaper, and therefore more practical. However, beam halo-chaos in ADS has become one of the key technical issues because it can cause excessive radio-activation from the accelerators and significantly limits the industrial applications of the new accelerators.Some general engineering methods for chaos control have been developed, but they generally

  14. Evidence for a Common Acceleration Mechanism for Enrichments of 3He and Heavy Ions in Impulsive SEP Events

    Science.gov (United States)

    Mason, Glenn M.; Nitta, Nariaki V.; Wiedenbeck, Mark E.; Innes, Davina E.

    2016-06-01

    We have surveyed the period 1997–2015 for a rare type of 3He-rich solar energetic particle (SEP) event, with enormously enhanced values of the S/O ratio, that differs from the majority of 3He-rich events, which show enhancements of heavy ions increasing smoothly with mass. Sixteen events were found, most of them small but with solar source characteristics similar to other 3He-rich SEP events. A single event on 2014 May 16 had higher intensities than the others, and curved Si and S spectra that crossed the O spectrum above ∼200 keV nucleon‑1. Such crossings of heavy-ion spectra have never previously been reported. The dual enhancement of Si and S suggests that element Q/M ratio is critical to the enhancement since this pair of elements uniquely has very similar Q/M ratios over a wide range of temperatures. Besides 3He, Si, and S, in this same event the C, N, and Fe spectra also showed curved shape and enhanced abundances compared to O. The spectral similarities suggest that all have been produced from the same mechanism that enhances 3He. The enhancements are large only in the high-energy portion of the spectrum, and so affect only a small fraction of the ions. The observations suggest that the accelerated plasma was initially cool (∼0.4 MK) and was then heated to a few million kelvin to generate the preferred Q/M ratio in the range C–Fe. The temperature profile may be the distinct feature of these events that produces the unusual abundance signature.

  15. Analytical study in the mechanism of flame movement in horizontal tubes. II. Flame acceleration in smooth open tubes

    CERN Document Server

    Kazakov, Kirill A

    2013-01-01

    The problem of spontaneous acceleration of premixed flames propagating in open horizontal tubes with smooth walls is revisited. It is proved that in long tubes, this process can be considered quasi-steady, and an equation for the flame front position is derived using the on-shell description. Numerical solutions of this equation are found which show that as in the case of uniform flame movement, there are two essentially different regimes of flame propagation. In the type I regime, the flame speed and its acceleration are comparatively low, whereas the type II regime is characterized by significant flame acceleration that rapidly increases as the flame travels along the tube. A detailed comparison of the obtained results with the experimental data on flame acceleration in methane-air mixtures is given. In particular, it is confirmed that flames propagating in near-stoichiometric mixtures and mixtures near the limits of inflammability belong to the types II and I, respectively, whereas flames in transient mixt...

  16. The effect of the accelerated aging on the mechanical properties of the PMMA denture base materials modified with itaconates

    Directory of Open Access Journals (Sweden)

    Spasojević Pavle M.

    2011-01-01

    Full Text Available This study evaluated the effect of accelerated ageing on the tensile strength, elongation at break, hardness and Charpy impact strength in commercial PMMA denture base material modified with di-methyl itaconate (DMI and di-n-butyl itaconate (DBI. The samples were prepared by modifying commercial formulation by addition of itaconates in the amounts of 2.5, 5, 7.5 and 10% by weight. After polymerization samples were characterized by FT-IR and DSC analysis while residual monomer content was determined by HPLC-UV. Accelerated ageing was performed at 70°C in water for periods of 7, 15 and 30 days. Tensile measurements were performed using Instron testing machine while the hardness of the polymerized samples was measured by Shore D method. The addition of itaconate significantly reduces the residual MMA. Even at the small amounts of added itaconates (2.5% the residual MMA content was reduced by 50%. The increase of itaconate content in the system leads to the decrease of residual MMA. It has been found that the addition of di-n-alkyl itaconates decreases the tensile strength, hardness and Charpy impact strength and increases elongation at break. Samples modified with DMI had higher values of tensile strength, hardness and Charpy impact strength compared to the ones modified with DBI. This is explained by the fact that DBI has longer side chain compared to DMI. After accelerated ageing during a 30 days period the tensile strength decreased for all the investigated samples. The addition of DMI had no effect on the material ageing and the values for the tensile strength of all of the investigated samples decreased around 20%, while for the samples modified with DBI, the increase of the amount of DBI in the polymerized material leads to the higher decrease of the tensile strength after the complete accelerated ageing period od 30 days, aulthough after the first seven days of the accelerated ageing the values of hardness have increased for all of the

  17. Novel durable bio-photocatalyst purifiers, a non-heterogeneous mechanism: accelerated entrapped dye degradation into structural polysiloxane-shield nano-reactors.

    Science.gov (United States)

    Dastjerdi, Roya; Montazer, Majid; Shahsavan, Shadi; Böttcher, Horst; Moghadam, M B; Sarsour, Jamal

    2013-01-01

    This research has designed innovative Ag/TiO(2) polysiloxane-shield nano-reactors on the PET fabric to develop novel durable bio-photocatalyst purifiers. To create these very fine nano-reactors, oppositely surface charged multiple size nanoparticles have been applied accompanied with a crosslinkable amino-functionalized polysiloxane (XPs) emulsion. Investigation of photocatalytic dye decolorization efficiency revealed a non-heterogeneous mechanism including an accelerated degradation of entrapped dye molecules into the structural polysiloxane-shield nano-reactors. In fact, dye molecules can be adsorbed by both Ag and XPs due to their electrostatic interactions and/or even via forming a complex with them especially with silver NPs. The absorbed dye and active oxygen species generated by TiO(2) were entrapped by polysiloxane shelter and the presence of silver nanoparticles further attract the negative oxygen species closer to the adsorbed dye molecules. In this way, the dye molecules are in close contact with concentrated active oxygen species into the created nano-reactors. This provides an accelerated degradation of dye molecules. This non-heterogeneous mechanism has been detected on the sample containing all of the three components. Increasing the concentration of Ag and XPs accelerated the second step beginning with an enhanced rate. Further, the treated samples also showed an excellent antibacterial activity.

  18. Linear Accelerators

    CERN Document Server

    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.

  19. Stochastic shock response spectrum decomposition method based on probabilistic definitions of temporal peak acceleration, spectral energy, and phase lag distributions of mechanical impact pyrotechnic shock test data

    Science.gov (United States)

    Hwang, James Ho-Jin; Duran, Adam

    2016-08-01

    Most of the times pyrotechnic shock design and test requirements for space systems are provided in Shock Response Spectrum (SRS) without the input time history. Since the SRS does not describe the input or the environment, a decomposition method is used to obtain the source time history. The main objective of this paper is to develop a decomposition method producing input time histories that can satisfy the SRS requirement based on the pyrotechnic shock test data measured from a mechanical impact test apparatus. At the heart of this decomposition method is the statistical representation of the pyrotechnic shock test data measured from the MIT Lincoln Laboratory (LL) designed Universal Pyrotechnic Shock Simulator (UPSS). Each pyrotechnic shock test data measured at the interface of a test unit has been analyzed to produce the temporal peak acceleration, Root Mean Square (RMS) acceleration, and the phase lag at each band center frequency. Maximum SRS of each filtered time history has been calculated to produce a relationship between the input and the response. Two new definitions are proposed as a result. The Peak Ratio (PR) is defined as the ratio between the maximum SRS and the temporal peak acceleration at each band center frequency. The ratio between the maximum SRS and the RMS acceleration is defined as the Energy Ratio (ER) at each band center frequency. Phase lag is estimated based on the time delay between the temporal peak acceleration at each band center frequency and the peak acceleration at the lowest band center frequency. This stochastic process has been applied to more than one hundred pyrotechnic shock test data to produce probabilistic definitions of the PR, ER, and the phase lag. The SRS is decomposed at each band center frequency using damped sinusoids with the PR and the decays obtained by matching the ER of the damped sinusoids to the ER of the test data. The final step in this stochastic SRS decomposition process is the Monte Carlo (MC

  20. Revisiting Caianiello's Maximal Acceleration

    OpenAIRE

    Papini, G.

    2003-01-01

    A quantum mechanical limit on the speed of orthogonality evolution justifies the last remaining assumption in Caianiello's derivation of the maximal acceleration. The limit is perfectly compatible with the behaviour of superconductors of the first type.

  1. Computer simulation of rocket/missile safing and arming mechanism (containing pin pallet runaway escapement, three-pass involute gear train and acceleration driven rotor)

    Science.gov (United States)

    Gorman, P. T.; Tepper, F. R.

    1986-03-01

    A complete simulation of missile and rocket safing and arming (S&A) mechanisms containing an acceleration-driven rotor, a three-pass involute gear train, and a pin pallet runaway escapement was developed. In addition, a modification to this simulation was formulated for the special case of the PATRIOT M143 S&A mechanism which has a pair of driving gears in addition to the three-pass gear train. The three motion regimes involved in escapement operation - coupled motion, free motion, and impact - are considered in the computer simulation. The simulation determines both the arming time of the device and the non-impact contact forces of all interacting components. The program permits parametric studies to be made, and is capable of analyzing pallets with arbitrarily located centers of mass. A sample simulation of the PATRIOT M143 S&A in an 11.9 g constant acceleration arming test was run. The results were in good agreement with laboratory test data.

  2. Future accelerators (?)

    Energy Technology Data Exchange (ETDEWEB)

    John Womersley

    2003-08-21

    I describe the future accelerator facilities that are currently foreseen for electroweak scale physics, neutrino physics, and nuclear structure. I will explore the physics justification for these machines, and suggest how the case for future accelerators can be made.

  3. Superposed-laser electron acceleration

    International Nuclear Information System (INIS)

    A new mechanism is proposed for electron acceleration by using two superposed laser beams in vacuum. In this mechanism, an electron is accelerated by the longitudinal component of the wave electric field in the overlapped region of two laser beams. Single-particle computations and analytical works are performed in order to demonstrate the viability. These results show that the electron can be accelerated well in this proposed mechanism. (author)

  4. Accelerating Value Creation with Accelerators

    DEFF Research Database (Denmark)

    Jonsson, Eythor Ivar

    2015-01-01

    accelerator programs. Microsoft runs accelerators in seven different countries. Accelerators have grown out of the infancy stage and are now an accepted approach to develop new ventures based on cutting-edge technology like the internet of things, mobile technology, big data and virtual reality. It is also...... with the traditional audit and legal universes and industries are examples of emerging potentials both from a research and business point of view to exploit and explore further. The accelerator approach may therefore be an Idea Watch to consider, no matter which industry you are in, because in essence accelerators...

  5. Laser accelerator

    OpenAIRE

    Vigil, Ricardo

    2014-01-01

    Approved for public release; distribution is unlimited In 1979,W. B. Colson and S. K. Ride proposed a new kind of electron accelerator using a uniform magnetic field in combination with a circularly-polarized laser field. A key concept is to couple the oscillating electric field to the electron’s motion so that acceleration is sustained. This dissertation investigates the performance of the proposed laser accelerator using modern high powered lasers and mag-netic fields that are significan...

  6. Self-consistent plasma heating and acceleration by strong magnetosonic waves for theta = 90 0. Part I: Basic mechanisms

    International Nuclear Information System (INIS)

    The behavior of strong magnetosonic waves propagating perpendicular to a static field B0 is investigated within the frequency range ω/sub c/i0 results; the electrons exhibit only poor heating associated with their adiabatic compression. The dynamics of both particle species, the consequences of the wave--particle energy transfer and the particle viscosities, are studied in detail. Competitive and self-consistent effects such as space-charge effects, wave overtaking, ion trapping, and wave damping are investigated and compared with previous models; the mechanisms by which these various phenomena interact on each other are analyzed. Characteristics of nonstochastic and stochastic ion heating are also discussed. Our computations show that if sufficient intensity is reached, one is not constrained to use lower-hybrid waves or cyclotron harmonic waves to heat a plasma efficiently and that any frequency below ω/sub lh/ can be used

  7. The acceleration of galactic cosmic rays

    International Nuclear Information System (INIS)

    A number of acceleration mechanisms are discussed including stochastic acceleration, shock acceleration, laminar shock acceleration and acceleration by shocks in scattering media. The self-consistent problem is analysed and it is concluded that provided the cosmic rays are scattered effectively and provided energy losses are not too severe, they can be very efficiently accelerated by shock waves in the interstellar medium. (C.F.)

  8. $K$-essence model from the mechanical approach point of view: coupled scalar field and the late cosmic acceleration

    CERN Document Server

    Bouhmadi-López, Mariam; Marto, João; Morais, João; Zhuk, Alexander

    2016-01-01

    In this paper, we consider the Universe at the late stage of its evolution and deep inside the cell of uniformity. At these scales, we can consider the Universe to be filled with dust-like matter in the form of discretely distributed galaxies, a $K$-essence scalar field, playing the role of dark energy, and radiation as matter sources. We investigate such a Universe in the mechanical approach. This means that the peculiar velocities of the inhomogeneities (in the form of galaxies) as well as the fluctuations of the other perfect fluids are non-relativistic. Such fluids are designated as coupled because they are concentrated around the inhomogeneities. In the present paper, we investigate the conditions under which the $K$-essence scalar field with the most general form for its action can become coupled. We investigate at the background level three particular examples of the $K$-essence models: (i) the pure kinetic $K$-essence field, (ii) a $K$-essence with a constant speed of sound and (iii) the $K$-essence m...

  9. LIBO accelerates

    CERN Multimedia

    2002-01-01

    The prototype module of LIBO, a linear accelerator project designed for cancer therapy, has passed its first proton-beam acceleration test. In parallel a new version - LIBO-30 - is being developed, which promises to open up even more interesting avenues.

  10. Collective ion acceleration

    International Nuclear Information System (INIS)

    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

  11. Bi-layer structure of counterstreaming energetic electron fluxes: a diagnostic tool of the acceleration mechanism in the Earth's magnetotail

    Directory of Open Access Journals (Sweden)

    D. V. Sarafopoulos

    2010-02-01

    Full Text Available For the first time we identify a bi-layer structure of energetic electron fluxes in the Earth's magnetotail and establish (using datasets mainly obtained by the Geotail Energetic Particles and Ion Composition (EPIC/ICS instrument that it actually provides strong evidence for a purely spatial structure. Each bi-layer event is composed of two distinct layers with counterstreaming energetic electron fluxes, parallel and antiparallel to the local ambient magnetic field lines; in particular, the tailward directed fluxes always occur in a region adjacent to the lobes. Adopting the X-line as a standard reconnection model, we determine the occurrence of bi-layer events relatively to the neutral point, in the substorm frame; four (out of the shown seven events are observed earthward and three tailward, a result implying that four events probably occurred with the substorm's local recovery phase. We discuss the bi-layer events in terms of the X-line model; they add more constraints for any candidate electron acceleration mechanism. It should be stressed that until this time, none proposed electron acceleration mechanism has discussed or predicted these layered structures with all their properties. Then we discuss the bi-layer events in terms of the much promising "akis model", as introduced by Sarafopoulos (2008. The akis magnetic field topology is embedded in a thinned plasma sheet and is potentially causing charge separation. We assume that as the Rc curvature radius of the magnetic field line tends to become equal to the ion gyroradius rg, then the ions become non-adiabatic. At the limit Rc=rg the demagnetization process is also under way and the frozen-in magnetic field condition is violated by strong wave turbulence; hence, the ion particles in this geometry are stochastically scattered. In addition, ion diffusion probably takes place across the magnetic field, since an

  12. 将机械式直线加速器用于采油机械的设想%An idea of applying mechanical linear accelerator to oil pumping system

    Institute of Scientific and Technical Information of China (English)

    刘泽峰; 李少果; 黄清世

    2001-01-01

    Mechanical linear accelerator is a new transmission devicedesigned on the basis of the parallel straight push rod linear reducer. To make use of its acceleration and stroke increment functions, an idea of applying the mechanical linear accelerator to oil pumping system is put forward. The design schemes for long stroke pumping unit and downhole stroke increment device both equipped with the mechanical linear accelerator are presented. The long stroke pumping unit with the linear accelerator is easy to realize compound balance and is predicted to have high mechanical efficiency and long service life. The downhole stroke increment device with the linear accelerator can increase the stroke of the subsurface pump plunger, therefore it provides the condition for modifying the existing pumping systems to long stroke pumping systems.%机械式直线加速器是根据平行直动推杆传动机构设计而成的新型传动装置,利用其加速和增程功能,提出两种采取对称布置的直线加速器实现长冲程、低冲次的抽油装置设计新方案:(1)采用直线加速器的长冲程抽油机,其结构合理,便于实现复合平衡,预计有较高的机械效率和较长的使用寿命;(2)采用直线加速器的抽油机井下增程装置,可使地面设备结构紧凑,比同类型长冲程抽油机的悬点载荷相对较低,对现有抽油机实施长冲程改造有着重要的实际意义。

  13. Thermo-mechanical, Wear and Fracture Behavior of High-density Polyethylene/Hydroxyapatite Nano Composite for Biomedical Applications:Effect of Accelerated Ageing

    Institute of Scientific and Technical Information of China (English)

    H.Fouad; R.Elleithy; Othman Y.Alothman

    2013-01-01

    The objective of this work is to demonstrate how the viscoelastic,thermal,rheological,hardness,wear resistance and fracture behavior of bioinert high-density polyethylene (HDPE) can be changed by the addition of hydroxyapatite (HAP) nano particles.Also the effects of accelerated thermal ageing on the composite properties have been investigated.Different weight fractions of HAP nano particles up to 30 wt% have been incorporated in HDPE matrix by using melt blending in co-rotating intermeshing twin screw extruder.The fracture toughness results showed a remarkable decrease in proportion to the HAP content.The differential scanning calorimetry results indicated that the melting temperature and crystallinity were affected by the addition of HAP nano particles into the matrix.The complex viscosity increased as the percentage of HAP increased due to the restriction of the molecular mobility.The dynamic mechanical analysis results revealed that higher storage modulus (8.3 1011 Pa) could be obtained in the developed HDPE/HAP in 30 wt% compared to neat HDPE (5.1 1011 Pa).Finally,the hardness and wear resistance of HDPE were improved significantly due to the addition of HAP nano particles.The changes in the HDPE and its nano composite properties due to ageing showed that the HDPE and its hang composites crystallinity increased while the fracture toughness,hardness,wear resistance,storage and loss modulus decreased.

  14. Accelerators in the sky

    International Nuclear Information System (INIS)

    The author surveys the large body of evidence showing that there are very efficient mechanisms capable of accelerating particles to high energies under very different astrophysical conditions. The circumstances whereby huge amounts of relativistic and ultrarelativistic particles such as one finds in a) cosmic rays, b) supernova remnants and c) radio galaxies and quasars are produced are considered. (Auth.)

  15. CAS CERN Accelerator School: Advanced accelerator physics. Proceedings. Vol. 1

    International Nuclear Information System (INIS)

    This advanced course on general accelerator physics is the second of the biennial series given by the CERN Accelerator School and follows on from the first basic course given at Gif-sur-Yvette, Paris, in 1984. Stress is placed on the mathematical tools of Hamiltonian mechanics and the Vlasov and Fokker-Planck equations, which are widely used in accelerator theory. The main topics treated in this present work include: nonlinear resonances, chromaticity, motion in longitudinal phase space, growth and control of longitudinal and transverse beam emittance, space-charge effects and polarization. The seminar programme treats some specific accelerator techniques, devices, projects and future possibilities. (orig.)

  16. CAS CERN Accelerator School: Advanced accelerator physics. Proceedings. Vol. 2

    International Nuclear Information System (INIS)

    This advanced course on general accelerator physics is the second of the biennial series given by the CERN Accelerator School and follows on from the first basic course given at Gif-sur-Yvette, Paris, in 1984. Stress is placed on the mathematical tools of Hamiltonian mechanics and the Vlasov and Fokker-Planck equations, which are widely used in accelerator theory. The main topics treated in this present work include: nonlinear resonances, chromaticity, motion in longitudinal phase space, growth and control of longitudinal and transverse beam emittance, space-charge effects and polarization. The seminar programme treats some specific accelerator techniques, devices, projects and future possibilities. (orig.)

  17. Shadows of a maximal acceleration

    OpenAIRE

    Papini, G.

    2002-01-01

    A quantum mechanical upper limit on the value of particle accelerations, or maximal acceleration (MA), is applied to compact stars. A few MA fermions are at most present in canonical white dwarfs and neutron stars. They drastically alter a star's stability conditions.

  18. Shadows of a maximal acceleration

    Energy Technology Data Exchange (ETDEWEB)

    Papini, G

    2002-12-16

    A quantum mechanical upper limit on the value of particle accelerations, or maximal acceleration (MA), is applied to compact stars. A few MA fermions are at most present in canonical white dwarfs and neutron stars. They drastically alter a star's stability conditions.

  19. Particle acceleration in space and laboratory plasmas

    International Nuclear Information System (INIS)

    The general principle of charged particle acceleration in space and laboratory plasmas is illustrated by a discussion of particular types of acceleration mechanisms which can be classified as either deterministic processes or stochastic processes. Acceleration by parallel electric fields, produced in double layers is an example of a deterministic process. Fermi acceleration and acceleration by turbulent wave fields are examples of stochastic processes. The physical acceleration mechanism involved in each type of process is discussed and examples given for space and laboratory plasmas. (author)

  20. Antibiotics as selectors and accelerators of diversity in the mechanisms of resistance: From the resistome to genetic plasticity in the beta-lactamases world

    Directory of Open Access Journals (Sweden)

    Juan- Carlos eGalán

    2013-02-01

    Full Text Available Antibiotics and antibiotic resistance determinants, natural molecules closely related to bacterial physiology and consistent with an ancient origin, are not only present in antibiotic-producing bacteria. Throughput sequencing technologies have revealed an unexpected reservoir of antibiotic resistance in the environment. These data suggest that co-evolution between antibiotic and antibiotic resistance genes has occurred since the beginning of time. This evolutionary race has probably been slow because of highly regulated processes and low antibiotic concentrations. Therefore to understand this global problem, a new variable must be introduced, that the antibiotic resistance is a natural event, inherent to life. However, the industrial production of natural and synthetic antibiotics has dramatically accelerated this race, selecting some of the many resistance genes present in nature and contributing to their diversification. One of the best models available to understand the biological impact of selection and diversification are -lactamases. They constitute the most widespread mechanism of resistance, at least among pathogenic bacteria, with more than 1000 enzymes identified in the literature. In the last years, there has been growing concern about the description, spread and diversification of -lactamases with carbapenemase activity and AmpC-type in plasmids. Phylogenies of these enzymes help the understanding of the evolutionary forces driving their selection. Moreover, understanding the adaptive potential of -lactamases contribute to exploration the evolutionary antagonists trajectories through the design of more efficient synthetic molecules. In this review, we attempt to analyse the antibiotic resistance problem from new perspectives. From intrinsic and environmental resistomes to the adaptive potential of resistance genes and the driving forces involved in their diversification, in order to provide a global perspective of the

  1. Accelerator operations

    International Nuclear Information System (INIS)

    This section is concerned with the operation of both the tandem-linac system and the Dynamitron, two accelerators that are used for entirely different research. Developmental activities associated with the tandem and the Dynamitron are also treated here, but developmental activities associated with the superconducting linac are covered separately because this work is a program of technology development in its own right

  2. Advanced accelerators

    International Nuclear Information System (INIS)

    This report discusses the suitability of four novel particle acceleration technologies for multi-TeV particle physics machines: laser driven linear accelerators (linac), plasma beat-wave devices, plasma wakefield devices, and switched power and cavity wakefield linacs. The report begins with the derivation of beam parameters practical for multi-TeV devices. Electromagnetic field breakdown of materials is reviewed. The two-beam accelerator scheme for using a free electron laser as the driver is discussed. The options recommended and the conclusions reached reflect the importance of cost. We recommend that more effort be invested in achieving a self-consistent range of TeV accelerator design parameters. Beat-wave devices have promise for 1-100 GeV applications and, while not directly scalable to TeV designs, the current generation of ideas are encouraging for the TeV regime. In particular, surfatrons, finite-angle optical mixing devices, plasma grating accelerator, and the Raman forward cascade schemes all deserve more complete analysis. The exploitation of standard linac geometry operated in an unconventional mode is in a phase of rapid evolution. While conceptual projects abound, there are no complete designs. We recommend that a fraction of sponsored research be devoted to this approach. Wakefield devices offer a great deal of potential; trades among their benefits and constraints are derived and discussed herein. The study of field limitation processes has received inadequate attention; this limits experiment designers. The costs of future experiments are such that investment in understanding these processes is prudent. 34 refs., 12 figs., 3 tabs

  3. Quantum aspects of accelerator optics

    OpenAIRE

    Khan, Sameen Ahmed

    1999-01-01

    Present understanding of accelerator optics is based mainly on classical mechanics and electrodynamics. In recent years quantum theory of charged-particle beam optics has been under development. In this paper the newly developed formalism is outlined.

  4. Superconducting accelerator magnet design

    International Nuclear Information System (INIS)

    Superconducting dipoles, quadrupoles and correction magnets are necessary to achieve the high magnetic fields required for big accelerators presently in construction or in the design phase. Different designs of superconducting accelerator magnets are described and the designs chosen at the big accelerator laboratories are presented. The most frequently used cosθ coil configuration is discussed in detail. Approaches for calculating the magnetic field quality including coil end fields are presented. Design details of the cables, coils, mechanical structures, yokes, helium vessels and cryostats including thermal radiation shields and support structures used in superconducting magnets are given. Necessary material properties are mentioned. Finally, the main results of magnetic field measurements and quench statistics are presented. (orig.)

  5. KEKB accelerator

    International Nuclear Information System (INIS)

    KEKB, the B-Factory at High Energy Accelerator Research Organization (KEK) recently achieved the luminosity of 1 x 1034 cm-2s-1. This luminosity is two orders higher than the world's level at 1990 when the design of KEKB started. This unprecedented result was made possible by KEKB's innovative design and technology in three aspects - beam focusing optics, high current storage, and beam - beam interaction. Now KEKB is leading the luminosity frontier of the colliders in the world. (author)

  6. Accelerating networks

    International Nuclear Information System (INIS)

    Evolving out-of-equilibrium networks have been under intense scrutiny recently. In many real-world settings the number of links added per new node is not constant but depends on the time at which the node is introduced in the system. This simple idea gives rise to the concept of accelerating networks, for which we review an existing definition and-after finding it somewhat constrictive-offer a new definition. The new definition provided here views network acceleration as a time dependent property of a given system as opposed to being a property of the specific algorithm applied to grow the network. The definition also covers both unweighted and weighted networks. As time-stamped network data becomes increasingly available, the proposed measures may be easily applied to such empirical datasets. As a simple case study we apply the concepts to study the evolution of three different instances of Wikipedia, namely, those in English, German, and Japanese, and find that the networks undergo different acceleration regimes in their evolution

  7. Accelerators and the Accelerator Community

    Energy Technology Data Exchange (ETDEWEB)

    Malamud, Ernest; Sessler, Andrew

    2008-06-01

    In this paper, standing back--looking from afar--and adopting a historical perspective, the field of accelerator science is examined. How it grew, what are the forces that made it what it is, where it is now, and what it is likely to be in the future are the subjects explored. Clearly, a great deal of personal opinion is invoked in this process.

  8. accelerating cavity

    CERN Multimedia

    On the inside of the cavitytThere is a layer of niobium. Operating at 4.2 degrees above absolute zero, the niobium is superconducting and carries an accelerating field of 6 million volts per metre with negligible losses. Each cavity has a surface of 6 m2. The niobium layer is only 1.2 microns thick, ten times thinner than a hair. Such a large area had never been coated to such a high accuracy. A speck of dust could ruin the performance of the whole cavity so the work had to be done in an extremely clean environment.

  9. Diffusive Shock Acceleration and Reconnection Acceleration Processes

    Science.gov (United States)

    Zank, G. P.; Hunana, P.; Mostafavi, P.; Le Roux, J. A.; Li, Gang; Webb, G. M.; Khabarova, O.; Cummings, A.; Stone, E.; Decker, R.

    2015-12-01

    Shock waves, as shown by simulations and observations, can generate high levels of downstream vortical turbulence, including magnetic islands. We consider a combination of diffusive shock acceleration (DSA) and downstream magnetic-island-reconnection-related processes as an energization mechanism for charged particles. Observations of electron and ion distributions downstream of interplanetary shocks and the heliospheric termination shock (HTS) are frequently inconsistent with the predictions of classical DSA. We utilize a recently developed transport theory for charged particles propagating diffusively in a turbulent region filled with contracting and reconnecting plasmoids and small-scale current sheets. Particle energization associated with the anti-reconnection electric field, a consequence of magnetic island merging, and magnetic island contraction, are considered. For the former only, we find that (i) the spectrum is a hard power law in particle speed, and (ii) the downstream solution is constant. For downstream plasmoid contraction only, (i) the accelerated spectrum is a hard power law in particle speed; (ii) the particle intensity for a given energy peaks downstream of the shock, and the distance to the peak location increases with increasing particle energy, and (iii) the particle intensity amplification for a particular particle energy, f(x,c/{c}0)/f(0,c/{c}0), is not 1, as predicted by DSA, but increases with increasing particle energy. The general solution combines both the reconnection-induced electric field and plasmoid contraction. The observed energetic particle intensity profile observed by Voyager 2 downstream of the HTS appears to support a particle acceleration mechanism that combines both DSA and magnetic-island-reconnection-related processes.

  10. High-energy cosmic-ray acceleration

    CERN Document Server

    Bustamante, M; de Paula, W; Duarte Chavez, J A; Gago, A M; Hakobyan, H; Jez, P; Monroy Montañez, J A; Ortiz Velasquez, A; Padilla Cabal, F; Pino Rozas, M; Rodriguez Patarroyo, D J; Romeo, G L; Saldaña-Salazar , U J; Velasquez, M; von Steinkirch, M

    2010-01-01

    We briefly review the basics of ultrahigh-energy cosmic-ray acceleration. The Hillas criterion is introduced as a geometrical criterion that must be fulfilled by potential acceleration sites, and energy losses are taken into account in order to obtain a more realistic scenario. The different available acceleration mechanisms are presented, with special emphasis on Fermi shock acceleration and its prediction of a power-law cosmic-ray energy spectrum. We conclude that first-order Fermi acceleration, though not entirely satisfactory, is the most promising mechanism for explaining the ultra-high-energy cosmic-ray flux.

  11. Particle Acceleration in Astrophysical Sources

    CERN Document Server

    Amato, Elena

    2015-01-01

    Astrophysical sources are extremely efficient accelerators. Some sources emit photons up to multi-TeV energies, a signature of the presence, within them, of particles with energies much higher than those achievable with the largest accelerators on Earth. Even more compelling evidence comes from the study of Cosmic Rays, charged relativistic particles that reach the Earth with incredibly high energies: at the highest energy end of their spectrum, these subatomic particles are carrying a macroscopic energy, up to a few Joules. Here I will address the best candidate sources and mechanisms as cosmic particle accelerators. I will mainly focus on Galactic sources such as Supernova Remnants and Pulsar Wind Nebulae, which being close and bright, are the best studied among astrophysical accelerators. These sources are held responsible for most of the energy that is put in relativistic particles in the Universe, but they are not thought to accelerate particles up to the highest individual energies, $\\approx 10^{20}$ eV...

  12. Understanding the Mechanisms Enabling an Ultra-high Efficiency Moving Wire Interface for Real-time Carbon 14 Accelerator Mass Spectrometry Quantitation of Samples Suspended in Solvent

    Science.gov (United States)

    Thomas, Avraham Thaler

    Carbon 14 (14C) quantitation by accelerator mass spectrometry (AMS) is a powerfully sensitive and uniquely quantitative tool for tracking labeled carbonaceous molecules in biological systems. This is due to 14C's low natural abundance of 1 ppt, the nominal difference in biological activity between an unlabeled and a 14C-labeled molecule, and the ability of AMS to measure isotopic ratios independently of a sample's other characteristics. To make AMS more broadly accessible, a moving wire interface for real-time coupling of high pressure liquid chromatography (HPLC) to AMS and high throughput AMS quantitation of minute single samples has been developed. Prior to this work, samples needed to be converted to solid carbon before measurement. This conversion process has many steps and requires that the sample size be large enough to allow precise handling of the resulting graphite. These factors make the process susceptible to error and time consuming, as well as requiring 0.5 ug of carbon. Samples which do not contain enough carbon, such as HPLC fractions, must be bulked up. This adds background and increases effort. The moving wire interface overcomes these limitations by automating sample processing. Samples placed on the wire are transported through a solvent removal stage followed by a combustion stage after which the combustion products are directed to a gas accepting ion source. The ion source converts the carbon from the CO2 combustion product into C ions, from which an isotopic ratio can be determined by AMS. Although moving wire interfaces have been implemented for various tasks since 1964, the efficiency of these systems at transferring fluid from an HPLC to the wire was only 3%, the efficiency of transferring combustion products from the combustion oven to ion source was only 30%, the flow and composition of the carrier gas from the combustion oven to the ion source needed to be optimized for coupling to an AMS gas accepting ion source and the drying ovens

  13. Caianiello's maximal acceleration. Recent developments

    OpenAIRE

    Papini, G.

    2004-01-01

    A quantum mechanical upper limit on the value of particle accelerations is consistent with the behavior of a class of superconductors and well known particle decay rates. It also sets limits on the mass of the Higgs boson and affects the stability of compact stars. In particular, type-I superconductors in static conditions offer an example of a dynamics in which acceleration has an upper limit.

  14. Sequentially pulsed traveling wave accelerator

    Science.gov (United States)

    Caporaso, George J.; Nelson, Scott D.; Poole, Brian R.

    2009-08-18

    A sequentially pulsed traveling wave compact accelerator having two or more pulse forming lines each with a switch for producing a short acceleration pulse along a short length of a beam tube, and a trigger mechanism for sequentially triggering the switches so that a traveling axial electric field is produced along the beam tube in synchronism with an axially traversing pulsed beam of charged particles to serially impart energy to the particle beam.

  15. Microwave View on Particle Acceleration in Flares

    CERN Document Server

    Fleishman, Gregory D

    2013-01-01

    The thermal-to-nonthermal partition was found to vary greatly from one flare to another resulting in a broad variety of cases from 'heating without acceleration' to 'acceleration without heating'. Recent analysis of microwave data of these differing cases suggests that a similar acceleration mechanism, forming a power-law nonthermal tail up to a few MeV or even higher, operates in all the cases. However, the level of this nonthermal spectrum compared to the original thermal distribution differs significantly from one case to another, implying a highly different thermal-to-nonthermal energy partition in various cases. This further requires a specific mechanism capable of extracting the charged particles from the thermal pool and supplying them to a bulk acceleration process to operate in flares \\textit{in addition} to the bulk acceleration process itself, which, in contrast, efficiently accelerates the seed particles, while cannot accelerate the thermal particles. Within this 'microwave' view on the flare ener...

  16. Particle-acceleration timescales in TeV blazar flares

    CERN Document Server

    Tammi, Joni

    2008-01-01

    Observations of minute-scale flares in TeV Blazars place constraints on particle acceleration mechanisms in those objects. The implications for a variety of radiation mechanisms have been addressed in the literature; in this paper we compare four different acceleration mechanisms: diffusive shock acceleration, second-order Fermi, shear acceleration and the converter mechanism. When the acceleration timescales and radiative losses are taken into account, we can exclude shear acceleration and the neutron-based converted mechanism as possible acceleration processes in these systems. The first-order Fermi process and the converter mechanism working via SSC photons are still practically instantaneous, however, provided sufficient turbulence is generated on the timescale of seconds. We propose stochastic acceleration as a promising candidate for the energy-dependent time delays in recent gamma-ray flares of Markarian 501.

  17. Mechanics

    CERN Document Server

    Hartog, J P Den

    1961-01-01

    First published over 40 years ago, this work has achieved the status of a classic among introductory texts on mechanics. Den Hartog is known for his lively, discursive and often witty presentations of all the fundamental material of both statics and dynamics (and considerable more advanced material) in new, original ways that provide students with insights into mechanical relationships that other books do not always succeed in conveying. On the other hand, the work is so replete with engineering applications and actual design problems that it is as valuable as a reference to the practicing e

  18. PROTON ACCELERATION AT OBLIQUE SHOCKS

    International Nuclear Information System (INIS)

    Acceleration at the shock waves propagating oblique to the magnetic field is studied using a recently developed theoretical/numerical model. The model assumes that resonant hydromagnetic wave-particle interaction is the most important physical mechanism relevant to motion and acceleration of particles as well as to excitation and damping of waves. The treatment of plasma and waves is self-consistent and time dependent. The model uses conservation laws and resonance conditions to find where waves will be generated or damped, and hence particles will be pitch-angle-scattered. The total distribution is included in the model and neither introduction of separate population of seed particles nor some ad hoc escape rate of accelerated particles is needed. Results of the study show agreement with diffusive shock acceleration models in the prediction of power spectra for accelerated particles in the upstream region. However, they also reveal the presence of spectral break in the high-energy part of the spectra. The role of the second-order Fermi-like acceleration at the initial stage of the acceleration is discussed. The test case used in the paper is based on ISEE-3 data collected for the shock of 1978 November 12.

  19. Proton Acceleration at Oblique Shocks

    Science.gov (United States)

    Galinsky, V. L.; Shevchenko, V. I.

    2011-06-01

    Acceleration at the shock waves propagating oblique to the magnetic field is studied using a recently developed theoretical/numerical model. The model assumes that resonant hydromagnetic wave-particle interaction is the most important physical mechanism relevant to motion and acceleration of particles as well as to excitation and damping of waves. The treatment of plasma and waves is self-consistent and time dependent. The model uses conservation laws and resonance conditions to find where waves will be generated or damped, and hence particles will be pitch-angle-scattered. The total distribution is included in the model and neither introduction of separate population of seed particles nor some ad hoc escape rate of accelerated particles is needed. Results of the study show agreement with diffusive shock acceleration models in the prediction of power spectra for accelerated particles in the upstream region. However, they also reveal the presence of spectral break in the high-energy part of the spectra. The role of the second-order Fermi-like acceleration at the initial stage of the acceleration is discussed. The test case used in the paper is based on ISEE-3 data collected for the shock of 1978 November 12.

  20. Accelerator structure work for NLC

    Energy Technology Data Exchange (ETDEWEB)

    Miller, R.H.; Adolphsen, C.; Bane, K.L.F.; Deruyter, H.; Farkas, Z.D.; Hoag, H.A.; Holtkamp, N.; Lavine, T.; Loew, G.A.; Nelson, E.M.; Palmer, R.B.; Paterson, J.M.; Ruth, R.D.; Thompson, K.A.; Vlieks, A.; Wang, J.W.; Wilson, P.B. [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Gluckstern, R. [Maryland Univ., College Park, MD (United States); Ko, K.; Kroll, N. [Stanford Linear Accelerator Center, Menlo Park, CA (United States)]|[California Univ., San Diego, La Jolla, CA (United States). Dept. of Physics

    1992-07-01

    The NLC design achieves high luminosity with multiple bunches in each RF pulse. Acceleration of a train of bunches without emittance growth requires control of long range dipole wakefields. SLAC is pursuing a structure design which suppresses the effect of wakefields by varying the physical dimensions of successive cells of the disk-loaded traveling wave structure in a manner which spreads the frequencies of the higher mode while retaining the synchronism between the electrons and the accelerating mode. The wakefields of structures incorporating higher mode detuning have been measured at the Accelerator Test Facility at Argonne. Mechanical design and brazing techniques which avoid getting brazing alloy into the interior of the accelerator are being studied. A test facility for high-power testing of these structures is complete and high power testing has begun.

  1. Linear Accelerator (LINAC)

    Science.gov (United States)

    ... News Physician Resources Professions Site Index A-Z Linear Accelerator A linear accelerator (LINAC) customizes high energy x-rays to ... ensured? What is this equipment used for? A linear accelerator (LINAC) is the device most commonly used ...

  2. 无碱液体水泥速凝剂的性能及其促凝机理%Performance and action mechanism of alkali-free liquid accelerating agent

    Institute of Scientific and Technical Information of China (English)

    刘梅艳; 何真; 蔡新华; 陈晓润

    2012-01-01

    A so-called macro and micro testing method is employed to study on the impact of alkali-free liquid accelerating agent on the performance of cement-based composites, and analyze its hydration mechanism. The results show that the impact of accelerating agent on cement hydration mainly happens in 1 day, however, it has little affect on cement hydration within 28 days. When accelerating agent adding is 6%, there are much more stick ettringite in the structure of cement paste hydrated 1 hour, those generated ettringite,interleaved filled in the pore of cement paste,makes the structure of cement paste more compact and high early strength. Action mechanism of alkali-free liquid accelerating agent is to form more ettringite to make cement setting. SEM pictures show that ettringite is produced by liquid chemical reaction-precipitation exhalation, those short column random oriented ettringite disordered distribute throughout the whole cement paste,which is the main reason why setting time had been shorten and the compressive had been increased.%采用宏微观试验方法,研究无碱液态水泥速凝剂对水泥基材料的性能影响及其水化机理.结果表明:无碱液体速凝剂对水泥水化作用主要体现在1d之内,水泥水化28d时几乎不起作用;掺加6%速凝剂1h水泥净浆硬化体有较多棒状AFt晶体形成,这些AFt晶体互相交错,填充在水泥浆体的孔隙中,使水泥净浆结构比基准水泥净浆结构更致密,使得其早期强度更高;无碱液体速凝剂的促凝机理主要是促进早期水泥浆体中AFt晶体的形成而达到促凝:SEM照片显示,生成的AFt是通过液相化学反应-沉淀析出途径生成,AFt晶体呈短柱状、随机取向,无序分布于整个硬化体空间,与基准水泥浆体形成的AFt途径完全不同,这可能是导致水泥浆体快速凝结及强度提高的主要原因.

  3. Cosmic-ray acceleration in young protostars

    CERN Document Server

    Padovani, Marco; Marcowith, Alexandre; Ferrière, Katia

    2015-01-01

    The main signature of the interaction between cosmic rays and molecular clouds is the high ionisation degree. This decreases towards the densest parts of a cloud, where star formation is expected, because of energy losses and magnetic effects. However recent observations hint to high levels of ionisation in protostellar systems, therefore leading to an apparent contradiction that could be explained by the presence of energetic particles accelerated within young protostars. Our modelling consists of a set of conditions that has to be satisfied in order to have an efficient particle acceleration through the diffusive shock acceleration mechanism. We find that jet shocks can be strong accelerators of protons which can be boosted up to relativistic energies. Another possibly efficient acceleration site is located at protostellar surfaces, where shocks caused by impacting material during the collapse phase are strong enough to accelerate protons. Our results demonstrate the possibility of accelerating particles du...

  4. Nonresonant Grain Acceleration in MHD Turbulence

    CERN Document Server

    Yan, Huirong

    2009-01-01

    We discuss a new type of dust acceleration mechanism that acts in a turbulent magnetized medium. The magnetohydrodynamic (MHD) turbulence can accelerate grains through resonant as well as nonresonant interactions. We show that the magnetic compression provides higher velocities for super-Alfv\\'enic turbulence and can accelerate an extended range of grains in warm media compared to gyroresonance. While fast modes dominate the acceleration for the large grains, slow modes can be important for sub-micron grains. We provide comprehensive discussion of all the possible grain acceleration mechanisms in interstellar medium. We show that supersonic velocities are attainable for Galactic dust grains. We discuss the consequence of the acceleration. The implications for extinction curve, grain alignment, chemical abundance, etc, are provided.

  5. Enhanced particle acceleration via cascade of autoresonance detrappings

    Energy Technology Data Exchange (ETDEWEB)

    Nakach, R. [Association Euratom-CEA, CEA Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee; Gell, Y. [CET, Tel-Aviv (Israel)

    1997-10-01

    We propose to enhance the acceleration of electrons by repeating consecutively a basic accelerating mechanism. This mechanism consists of trapping the particles in a traveling ponderomotive well, then autoresonance detrapping them allowing for considerable acceleration. The traveling well is generated by two counterpropagating electromagnetic waves along a uniform magnetic field. (author) 8 refs.

  6. Accelerating cosmology in Rastall's theory

    CERN Document Server

    Capone, Monica; Ruggiero, Matteo Luca

    2009-01-01

    In an attempt to look for a viable mechanism leading to a present day accelerated expansion, we investigate the possibility that the observed cosmic speed up may be recovered in the framework of the Rastall's theory, relying on the non - conservativity of the stress - energy tensor, i.e. $T^{\\mu}_{\

  7. Acceleration of Ca(2+) repletion in the junctional sarcoplasmic reticulum and alternation of the Ca(2+)-induced Ca(2+)-release mechanism in hypertensive rat (SHR) cardiac muscle.

    Science.gov (United States)

    Tanaka, Midori; Tameyasu, Tsukasa

    2008-04-01

    We estimated the time taken for a repletion of the junctional sarcoplasmic reticulum (JSR) Ca(2+) stores from a family of mechanical restitution curves after twitches of various magnitudes in the cardiac muscle of hypertensive rats (SHR), using a method described previously (Tameyasu et al. Jpn J Physiol. 2004;54:209-19), to evaluate abnormality in Ca(2+) handling by cardiac JSR in hypertension. We found no differences in contractility or in the time course of mechanical restitution between SHR and the controls (WKY) at 3 weeks of age. In comparison to WKY, 7- and 20-week-old SHR showed a greater rested state contraction (RST) and similar or smaller rapid cooling contracture, suggesting that their JSR contains a similar amount of Ca(2+) at saturation, but releases more Ca(2+) upon stimulation. The adult SHR and WKY showed similar mechanical restitution time courses, but the adults had longer pretwitch latencies. The function G(t) representing the time course of JSR Ca(2+) store repletion in adult SHR exceeded the WKY value at t JSR [Ca(2+)] change corresponding to the mechanical restitution after RST was smaller in the adult SHR at t JSR Ca(2+) store repletion and an alternation of the Ca(2+)-induced release of Ca(2+ )from the JSR in young adult SHR. PMID:18312741

  8. Study of the mechanisms of heavy-ion induced desorption on accelerator-relevant materials; Untersuchung der Mechanismen schwerioneninduzierter Desorption an beschleunigerrelevanten Materialien

    Energy Technology Data Exchange (ETDEWEB)

    Bender, Markus

    2008-02-22

    The ion beam loss induced desorption is a performance limitation for low charge state heavy ion accelerators. If charge exchanged projectile ions get lost onto the beam pipe, desorption of gas is stimulated resulting in a pressure increase inside of the synchrotron and thus, a dramatically reduction of the beam life time. To minimize the amount of desorbed gas an experimental program has been started to measure the desorption yields (released gas molecules per incident ion) of various materials and different projectile ions. The present work is a contribution to the understanding of the physical processes behind the ion beam loss induced desorption. The yield measurements by the pressure rise method have been combined for the rst time with in situ ion beam analysis technologies such as ERDA and RBS. With this unique method the desorption behavior of a sample can be correlated to its surface and bulk properties. The performed experiments with 1,4 MeV/u Xenon-Ions show that the ion induced desorption is mainly a surface effect. Sputtered oxide layers or impurities do not contribute to the desorbed gas significantly. Nevertheless bulk properties play an important role in the desorption strength. Pure metallic samples desorb less gas than isolating materials under swift heavy ion irradiation. From the experimental results it was possible to estimate the desorption yields of various materials under ion bombardment by means of an extended inelastic thermal-spike-model. The extension is the combination of the thermal-spike's temperature map with thermal desorption. Within this model the ion induced desorption can be regarded as the release of adsorbates from a transient overheated spot on the samples surface around the ion impact. Finally a copper substrate with a gold coated surface was developed and proposed as a suitable material for a beam loss collimator with minimum desorption to ensure the performance of GSI's SIS18 in high current beam operation. (orig.)

  9. Application of Plasma Waveguides to High Energy Accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Milchberg, Howard [Univ. of Maryland, College Park, MD (United States)

    2016-07-01

    This grant supported basic experimental, theoretical and computer simulation research into developing a compact, high pulse repetition rate laser accelerator using the direct laser acceleration mechanism in plasma-based slow wave structures.

  10. Mechanics

    CERN Document Server

    Chester, W

    1979-01-01

    When I began to write this book, I originally had in mind the needs of university students in their first year. May aim was to keep the mathematics simple. No advanced techniques are used and there are no complicated applications. The emphasis is on an understanding of the basic ideas and problems which require expertise but do not contribute to this understanding are not discussed. How­ ever, the presentation is more sophisticated than might be considered appropri­ ate for someone with no previous knowledge of the subject so that, although it is developed from the beginning, some previous acquaintance with the elements of the subject would be an advantage. In addition, some familiarity with element­ ary calculus is assumed but not with the elementary theory of differential equations, although knowledge of the latter would again be an advantage. It is my opinion that mechanics is best introduced through the motion of a particle, with rigid body problems left until the subject is more fully developed. Howev...

  11. Accelerator mass spectrometry programme at BARC-TIFR pelletron accelerator

    International Nuclear Information System (INIS)

    Accelerator based mass spectrometry (ABMs) is an ultra sensitive means of counting individual atoms having sufficiently long half life and available in small amount. The 14 U D Pelletron Accelerator is an ideal machine to carry out ABMs studies with heavy isotopes like 36Cl and 129I. Cosmogenic radio isotope 36Cl is widely being detected using ABMs as it has got applications in ground water research, radioactive waste management, atmospheric 36Cl transport mechanism studies of Arctic Alpine ice core etc. As a part of the ongoing ABMs programme at 14UD Pelletron Accelerator Facility at Mumbai, a segmented gas detector developed for identification of 36Cl was tested for performance. Recently a beam chopper required for this measurement has been developed. Further progress made in this programme is discussed in this paper. (author)

  12. Conditioning and breakdown phenomena in accelerator tubes

    International Nuclear Information System (INIS)

    Important breakdown mechanisms in accelerator tubes are reviewed, and discharge phenomena in NEC tubes are deduced from the surface appearance of the electrodes and insulators of a used tube. Microphotos of these surfaces are shown

  13. 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/

  14. The direction of acceleration

    Science.gov (United States)

    Wilhelm, Thomas; Burde, Jan-Philipp; Lück, Stephan

    2015-11-01

    Acceleration is a physical quantity that is difficult to understand and hence its complexity is often erroneously simplified. Many students think of acceleration as equivalent to velocity, a ˜ v. For others, acceleration is a scalar quantity, which describes the change in speed Δ|v| or Δ|v|/Δt (as opposed to the change in velocity). The main difficulty with the concept of acceleration therefore lies in developing a correct understanding of its direction. The free iOS app AccelVisu supports students in acquiring a correct conception of acceleration by showing acceleration arrows directly at moving objects.

  15. High intensity laser-driven ion acceleration

    International Nuclear Information System (INIS)

    Ion acceleration by intense laser-plasma interactions is a very active field of research whose development can be traced in a large number of publications over the last few years. Past studies were mostly performed irradiating thin foils where protons are predominantly accelerated to energies up to 60 MeV in an exponentially decaying spectrum by a mechanism named target normal sheath acceleration (TNSA). We present our latest experimental advances on acceleration schemes away from TNSA, such as shock acceleration, ion beam generation from relativistically transparent targets and radiation-pressure acceleration. These results are a major step towards highly energetic, mono-chromatic ion beams generated at high conversion efficiencies as demanded by many potential applications. Those include fast ignition inertial confinement fusion (ICF) as well as oncology and radiation therapy of tumors.

  16. The Diffusive Shock Acceleration Myth

    Science.gov (United States)

    Gloeckler, G.; Fisk, L. A.

    2012-12-01

    It is generally accepted that diffusive shock acceleration (DSA) is the dominant mechanism for particle acceleration at shocks. This is despite the overwhelming observational evidence that is contrary to predictions of DSA models. For example, our most recent survey of hourly-averaged, spin-averaged proton distribution functions around 61 locally observed shocks in 2001 at 1 AU found that in 21 cases no particles were accelerated. Spectral indices (γ ) of suprathermal tails on the velocity distributions around the 40 shocks that did accelerate particles, showed none of the DSA-predicted correlations of γ with the shock compression ratio and the shock normal to magnetic field angle. Here we will present ACE/SWICS observations of three sets of 72 consecutive one-hour averaged velocity distributions (in each of 8 SWICS spin sectors). Each set includes passage of one or more shocks or strong compression regions. All spectra were properly transformed to the solar wind frame using the detailed, updated SWICS forward model, taking into account the hourly-averaged directions of the solar wind flow, the magnetic field and the ACE spin axis (http://www.srl.caltech.edu/ACE/ASC/). The suprathermal tails are observed to be a combination of locally accelerated and remote tails. The local tails are power laws. The remote tails are also power laws with rollovers at higher energies. When local tails are weak (as is the case especially upstream of strong shocks or compression regions) the remote tails also have a rollover at low energies due to modulation (transport effects). Among our main findings are that (1) the spectral indices of both the local and remote tails are -5 within the uncertainties of the measurements, as predicted by our pump acceleration mechanism, and (2) the velocity distributions are anisotropic with the perpendicular (to the magnetic field) pressure greater than the parallel pressure.

  17. Accelerated bone ingrowth by local delivery of Zinc from bioactive glass: oxidative stress status, mechanical property, and microarchitectural characterization in an ovariectomized rat model

    Directory of Open Access Journals (Sweden)

    Jbahi Samira

    2015-10-01

    Full Text Available Background: Synthetic bone graft substitutes such as bioactive glass (BG material are developed in order to achieve successful bone regeneration. Zn plays an important role in the proper bone growth, development, and maintenance of healthy bones. Aims: This study aims to evaluate in vivo the performance therapy of zinc-doped bioactive glass (BG-Zn and its applications in biomedicine. Methods: Female Wistar rats were ovariectomized. BG and BG-Zn were implanted in the femoral condyles of Wistar rats and compared to that of control group. Grafted bone tissues were carefully removed to evaluate the oxidative stress status, histomorphometric profile, mechanical property, and mineral bone distribution by using inductively coupled plasma optical emission spectrometry. Results: A significant decrease of thiobarbituric acid–reactive substances was observed after BG-Zn implantation. Superoxide dismutase, catalase (CAT, and glutathione peroxidase (GPx activities significantly increased in ovariectomized group implanted with Zinc-doped bioactive glass (OVX-BG-Zn as compared to ovariectomized group implanted with bioactive glass (OVX-BG. An improved mechanical property was noticed in contact of OVX-BG-Zn (39±6 HV when compared with that of OVX-BG group (26±9 HV. After 90 days of implantation, the histomorphometric analysis showed that trabecular thickness (Tb.Th and trabecular number (Tb.N were significantly increased with 28 and 24%, respectively, in treated rats of OVX-BG-Zn group as compared to those of OVX-BG groups. Trabecular separation (Tb.Sp and trabecular bone pattern factor (TBPf were significantly decreased in OVX-BG-Zn group with 29.5 and 54% when compared with those of OVX-BG rat groups. On the other hand, a rise in Ca and P ion concentrations in the implanted microenvironment was shown and lead to the formation/deposition of Ca-P phases. The ratio of pyridinoline [Pyr] to dihydroxylysinonorleucine [DHLNL] cross-links was normalized to the

  18. Accelerating Compact Object Mergers in Triple Systems with the Kozai Resonance: A Mechanism for "Prompt'' Type Ia Supernovae, Gamma-Ray Bursts, and Other Exotica

    CERN Document Server

    Thompson, Todd A

    2010-01-01

    The mechanism of Type Ia supernovae and gamma-ray bursts (GRBs) is unknown, but a subset of both may be due to white dwarf-white dwarf (WD-WD) and neutron star-neutron star (NS-NS) mergers, respectively. A general problem with this picture is the production of binaries with semi-major axes small enough to merge via gravitational wave (GW) emission in significantly less than the Hubble time (t_H), and thus accommodate the observation that these events closely follow episodes of star formation in time. I explore the possibility that such systems are not binaries at all, but actually coeval, or dynamical formed, hierarchical triple systems. The tertiary induces Kozai oscillations in the inner binary, driving it to high eccentricity, and dramatically reducing its GW merger timescale. This effect significantly increases the allowed range of binary period P such that the merger time is t_merge < t_H. I find that Chandrasehkar mass binaries with P as large as ~300 days can in fact merge in < t_H if they contai...

  19. San Francisco Accelerator Conference

    International Nuclear Information System (INIS)

    'Where are today's challenges in accelerator physics?' was the theme of the open session at the San Francisco meeting, the largest ever gathering of accelerator physicists and engineers

  20. Improved plasma accelerator

    Science.gov (United States)

    Cheng, D. Y.

    1971-01-01

    Converging, coaxial accelerator electrode configuration operates in vacuum as plasma gun. Plasma forms by periodic injections of high pressure gas that is ionized by electrical discharges. Deflagration mode of discharge provides acceleration, and converging contours of plasma gun provide focusing.

  1. Standing wave linear accelerator

    International Nuclear Information System (INIS)

    Consideration is being given to standing wave linear accelerator containing generator, phase shifter, two accelerating resonator sections, charged particle injector and waveguide bridge. Its first arm is oined up with generator via the phase shifter, the second and the third ones-with accelerating sections and the fourth one - with HF-power absorber. HF-power absorber represents a section of circular diaphragmatic wavequide with transformer with input wave and intrawaveguide output load located between injector and the first accelerating section. The section possesses holes in side walls lying on accelerator axis. The distances between centers of the last cell of the fast accelerating section and the first cell of the second accelerating sectiOn equal (2n+3)lambda/4, where n=1, 2, 3..., lambda - wave length of generator. The suggested system enables to improve by one order spectral characteristics of accelerators as compared to the prototype in which magnetrons are used as generator

  2. Accelerator Technology Division

    Science.gov (United States)

    1992-04-01

    In fiscal year (FY) 1991, the Accelerator Technology (AT) division continued fulfilling its mission to pursue accelerator science and technology and to develop new accelerator concepts for application to research, defense, energy, industry, and other areas of national interest. This report discusses the following programs: The Ground Test Accelerator Program; APLE Free-Electron Laser Program; Accelerator Transmutation of Waste; JAERI, OMEGA Project, and Intense Neutron Source for Materials Testing; Advanced Free-Electron Laser Initiative; Superconducting Super Collider; The High-Power Microwave Program; (Phi) Factory Collaboration; Neutral Particle Beam Power System Highlights; Accelerator Physics and Special Projects; Magnetic Optics and Beam Diagnostics; Accelerator Design and Engineering; Radio-Frequency Technology; Free-Electron Laser Technology; Accelerator Controls and Automation; Very High-Power Microwave Sources and Effects; and GTA Installation, Commissioning, and Operations.

  3. High Energy Particle Accelerators

    CERN Multimedia

    Audio Productions, Inc, New York

    1960-01-01

    Film about the different particle accelerators in the US. Nuclear research in the US has developed into a broad and well-balanced program.Tour of accelerator installations, accelerator development work now in progress and a number of typical experiments with high energy particles. Brookhaven, Cosmotron. Univ. Calif. Berkeley, Bevatron. Anti-proton experiment. Negative k meson experiment. Bubble chambers. A section on an electron accelerator. Projection of new accelerators. Princeton/Penn. build proton synchrotron. Argonne National Lab. Brookhaven, PS construction. Cambridge Electron Accelerator; Harvard/MIT. SLAC studying a linear accelerator. Other research at Madison, Wisconsin, Fixed Field Alternate Gradient Focusing. (FFAG) Oakridge, Tenn., cyclotron. Two-beam machine. Comments : Interesting overview of high energy particle accelerators installations in the US in these early years. .

  4. Low doses of LPS and minimally oxidized LDL cooperatively activate macrophages via NF-kappaB and AP-1: Possible mechanism for acceleration of atherosclerosis by subclinical endotoxemia

    Science.gov (United States)

    Wiesner, Philipp; Choi, Soo-Ho; Almazan, Felicidad; Benner, Christopher; Huang, Wendy; Diehl, Cody J.; Gonen, Ayelet; Butler, Susan; Witztum, Joseph L.; Glass, Christopher K.; Miller, Yury I.

    2010-01-01

    Rationale Oxidized low-density lipoprotein (LDL) is an important determinant of inflammation in atherosclerotic lesions. It has also been documented that certain chronic infectious diseases, such as periodontitis and chlamydial infection, exacerbate clinical manifestations of atherosclerosis. In addition, low-level but persistent metabolic endotoxemia is often found in diabetic and obese subjects and is induced in mice fed a high-fat diet. Objective In this study, we examined cooperative macrophage activation by low levels of bacterial LPS and by minimally oxidized LDL (mmLDL), as a model for subclinical endotoxemia-complicated atherosclerosis. Methods and Results We found that both in vitro and in vivo, mmLDL and LPS (Kdo2-LipidA) cooperatively activated macrophages to express pro-inflammatory cytokines Cxcl2 (MIP-2), Ccl3 (MIP-1alpha), and Ccl4 (MIP-1beta). Importantly, the mmLDL and LPS cooperative effects were evident at a threshold LPS concentration (1 ng/ml) at which LPS alone induced only a limited macrophage response. Analyzing microarray data with a de novo motif discovery algorithm, we found that genes transcribed by promoters containing an AP-1 binding site were significantly upregulated by co-stimulation with mmLDL and LPS. In a nuclear factor-DNA binding assay, the cooperative effect of mmLDL and LPS co-stimulation on c-Jun and c-Fos DNA binding, but not on p65 or p50, was dependent on mmLDL-induced activation of ERK1/2. In addition, mmLDL induced JNK-dependent derepression of AP-1 by removing the corepressor NCoR from the chemokine promoters. Conclusions The cooperative engagement of AP-1 and NF-kappaB by mmLDL and LPS may constitute a mechanism of increased transcription of inflammatory cytokines within atherosclerotic lesions. PMID:20489162

  5. Maximal Acceleration Is Nonrotating

    OpenAIRE

    Page, Don N.

    1997-01-01

    In a stationary axisymmetric spacetime, the angular velocity of a stationary observer that Fermi-Walker transports its acceleration vector is also the angular velocity that locally extremizes the magnitude of the acceleration of such an observer, and conversely if the spacetime is also symmetric under reversing both t and phi together. Thus a congruence of Nonrotating Acceleration Worldlines (NAW) is equivalent to a Stationary Congruence Accelerating Locally Extremely (SCALE). These congruenc...

  6. A Solid state accelerator

    International Nuclear Information System (INIS)

    We present a solid state accelerator concept utilizing particle acceleration along crystal channels by longitudinal electron plasma waves in a metal. Acceleration gradients of order 100 GV/cm are theoretically possible, but channeling radiation limits the maximum attainable energy to 105 TeV for protons. Beam dechanneling due to multiple scattering is substantially reduced by the high acceleration gradient. Plasma wave dissipation and generation in metals are also discussed

  7. Applications of particle accelerators

    International Nuclear Information System (INIS)

    Particle accelerators are now widely used in a variety of applications for scientific research, applied physics, medicine, industrial processing, while possible utilisation in power engineering is envisaged. Earlier presentations of this subject, given at previous CERN Accelerator School sessions have been updated with papers contributed to the first European Conference on Accelerators in Applied Research and Technology (ECAART) held in September 1989 in Frankfurt and to the Second European Particle Accelerator Conference in Nice in June 1990. (orig.)

  8. Accelerators at school

    International Nuclear Information System (INIS)

    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

  9. Acceleration: It's Elementary

    Science.gov (United States)

    Willis, Mariam

    2012-01-01

    Acceleration is one tool for providing high-ability students the opportunity to learn something new every day. Some people talk about acceleration as taking a student out of step. In actuality, what one is doing is putting a student in step with the right curriculum. Whole-grade acceleration, also called grade-skipping, usually happens between…

  10. The CERN Accelerator School

    CERN Multimedia

    2016-01-01

    Introduction to accelerator physics The CERN Accelerator School: Introduction to Accelerator Physics, which should have taken place in Istanbul, Turkey, later this year has now been relocated to Budapest, Hungary.  Further details regarding the new hotel and dates will be made available as soon as possible on a new Indico site at the end of May.

  11. Accelerators and Dinosaurs

    CERN Document Server

    Turner, Michael Stanley

    2003-01-01

    Using naturally occuring particles on which to research might have made accelerators become extinct. But in fact, results from astrophysics have made accelerator physics even more important. Not only are accelerators used in hospitals but they are also being used to understand nature's inner workings by searching for Higgs bosons, CP violation, neutrino mass and dark matter (2 pages)

  12. Far field acceleration

    Energy Technology Data Exchange (ETDEWEB)

    Fernow, R.C.

    1995-07-01

    Far fields are propagating electromagnetic waves far from their source, boundary surfaces, and free charges. The general principles governing the acceleration of charged particles by far fields are reviewed. A survey of proposed field configurations is given. The two most important schemes, Inverse Cerenkov acceleration and Inverse free electron laser acceleration, are discussed in detail.

  13. Direct Laser Acceleration in Laser Wakefield Accelerators

    OpenAIRE

    Shaw, Jessica

    2016-01-01

    In this dissertation, the direct laser acceleration (DLA) of ionization-injected electrons in a laser wakefield accelerator (LWFA) operating in the quasi-blowout regime has been investigated through experiment and simulation. In the blowout regime of LWFA, the radiation pressure of an intense laser pulse can push a majority of the plasma electrons out and around the main body of the pulse. The expelled plasma electrons feel the electrostatic field of the relatively-stationary ions and are t...

  14. 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.

  15. Induction linear accelerators

    Science.gov (United States)

    Birx, Daniel

    1992-03-01

    Among the family of particle accelerators, the Induction Linear Accelerator is the best suited for the acceleration of high current electron beams. Because the electromagnetic radiation used to accelerate the electron beam is not stored in the cavities but is supplied by transmission lines during the beam pulse it is possible to utilize very low Q (typicallymarriage of liner accelerator technology and nonlinear magnetic compressors has produced some unique capabilities. It now appears possible to produce electron beams with average currents measured in amperes, peak currents in kiloamperes and gradients exceeding 1 MeV/meter, with power efficiencies approaching 50%. The nonlinear magnetic compression technology has replaced the spark gap drivers used on earlier accelerators with state-of-the-art all-solid-state SCR commutated compression chains. The reliability of these machines is now approaching 1010 shot MTBF. In the following paper we will briefly review the historical development of induction linear accelerators and then discuss the design considerations.

  16. Particle-accelerator decommissioning

    International Nuclear Information System (INIS)

    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

  17. Particle-accelerator decommissioning

    Energy Technology Data Exchange (ETDEWEB)

    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.

  18. Particle acceleration by shocks in supernova remnants

    CERN Document Server

    Bell, A R

    2013-01-01

    Particle acceleration occurs on a range of scales from AU in the heliosphere to Mpc in clusters of galaxies and to energies ranging from MeV to EeV. A number of acceleration processes have been proposed, but diffusive shock acceleration (DSA) is widely invoked as the predominant mechanism. DSA operates on all these scales and probably to the highest energies. DSA is simple, robust and predicts a universal spectrum. However there are still many unknowns regarding particle acceleration. This paper focuses on the particular question of whether supernova remnants (SNR) can produce the Galactic CR spectrum up to the knee at a few PeV. The answer depends in large part on the detailed physics of diffusive shock acceleration.

  19. ACCELERATING POLARIZED PROTONS TO HIGH ENERGY.

    Energy Technology Data Exchange (ETDEWEB)

    BAI, M.; AHRENS, L.; ALEKSEEV, I.G.; ALESSI, J.; BEEBE-WANG, J.; BLASKIEWICZ, M.; BRAVAR, A.; BRENNAN, J.M.; BRUNO, D.; BUNCE, G.; ET AL.

    2006-10-02

    The Relativistic Heavy Ion Collider (RHIC) is designed to provide collisions of high energy polarized protons for the quest of understanding the proton spin structure. Polarized proton collisions at a beam energy of 100 GeV have been achieved in RHIC since 2001. Recently, polarized proton beam was accelerated to 250 GeV in RHIC for the first time. Unlike accelerating unpolarized protons, the challenge for achieving high energy polarized protons is to fight the various mechanisms in an accelerator that can lead to partial or total polarization loss due to the interaction of the spin vector with the magnetic fields. We report on the progress of the RHIC polarized proton program. We also present the strategies of how to preserve the polarization through the entire acceleration chain, i.e. a 200 MeV linear accelerator, the Booster, the AGS and RHIC.

  20. Phase space quantum mechanics and maximal acceleration

    Science.gov (United States)

    Caianiello, Eduardo

    1989-03-01

    It is a great honour to be asked to dedicate one's work to Eugene P. Wigner. I do so with humility and reverence, and warmest affection and gratitude for all that, directly or indirectly, I owe to him as a Person and a Teacher.

  1. 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.

  2. Switched Matrix Accelerator

    International Nuclear Information System (INIS)

    We describe a new concept for a microwave circuit functioning as a charged-particle accelerator at mm-wavelengths, permitting an accelerating gradient higher than conventional passive circuits can withstand consistent with cyclic fatigue. The device provides acceleration for multiple bunches in parallel channels, and permits a short exposure time for the conducting surface of the accelerating cavities. Our analysis includes scalings based on a smooth transmission line model and a complementary treatment with a coupled-cavity simulation. We provide also an electromagnetic design for the accelerating structure, arriving at rough dimensions for a seven-cell accelerator matched to standard waveguide and suitable for bench tests at low power in air at 91.392. GHz. A critical element in the concept is a fast mm-wave switch suitable for operation at high-power, and we present the considerations for implementation in an H-plane tee. We discuss the use of diamond as the photoconductor switch medium

  3. Accelerator and radiation physics

    CERN Document Server

    Basu, Samita; Nandy, Maitreyee

    2013-01-01

    "Accelerator and radiation physics" encompasses radiation shielding design and strategies for hadron therapy accelerators, neutron facilities and laser based accelerators. A fascinating article describes detailed transport theory and its application to radiation transport. Detailed information on planning and design of a very high energy proton accelerator can be obtained from the article on radiological safety of J-PARC. Besides safety for proton accelerators, the book provides information on radiological safety issues for electron synchrotron and prevention and preparedness for radiological emergencies. Different methods for neutron dosimetry including LET based monitoring, time of flight spectrometry, track detectors are documented alongwith newly measured experimental data on radiation interaction with dyes, polymers, bones and other materials. Design of deuteron accelerator, shielding in beam line hutches in synchrotron and 14 MeV neutron generator, various radiation detection methods, their characteriza...

  4. Leaky Fermi accelerators

    CERN Document Server

    Shah, Kushal; Rom-Kedar, Vered; Turaev, Dmitry

    2015-01-01

    A Fermi accelerator is a billiard with oscillating walls. A leaky accelerator interacts with an environment of an ideal gas at equilibrium by exchange of particles through a small hole on its boundary. Such interaction may heat the gas: we estimate the net energy flow through the hole under the assumption that the particles inside the billiard do not collide with each other and remain in the accelerator for sufficiently long time. The heat production is found to depend strongly on the type of the Fermi accelerator. An ergodic accelerator, i.e. one which has a single ergodic component, produces a weaker energy flow than a multi-component accelerator. Specifically, in the ergodic case the energy gain is independent of the hole size, whereas in the multi-component case the energy flow may be significantly increased by shrinking the hole size.

  5. Nuclear physics accelerator facilities

    International Nuclear Information System (INIS)

    This paper describes many of the nuclear physics heavy-ion accelerator facilities in the US and the research programs being conducted. The accelerators described are: Argonne National Laboratory--ATLAS; Brookhaven National Laboratory--Tandem/AGS Heavy Ion Facility; Brookhaven National Laboratory--Relativistic Heavy Ion Collider (RHIC) (Proposed); Continuous Electron Beam Accelerator Facility; Lawrence Berkeley Laboratory--Bevalac; Lawrence Berkeley Laboratory--88-Inch Cyclotron; Los Alamos National Laboratory--Clinton P. Anderson Meson Physics Facility (LAMPF); Massachusetts Institute of Technology--Bates Linear Accelerator Center; Oak Ridge National Laboratory--Holifield Heavy Ion Research Facility; Oak Ridge National Laboratory--Oak Ridge Electron Linear Accelerator; Stanford Linear Accelerator Center--Nuclear Physics Injector; Texas AandM University--Texas AandM Cyclotron; Triangle Universities Nuclear Laboratory (TUNL); University of Washington--Tandem/Superconducting Booster; and Yale University--Tandem Van de Graaff

  6. Accelerator reliability workshop

    International Nuclear Information System (INIS)

    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

  7. Particle acceleration at a reconnecting magnetic separator

    CERN Document Server

    Threlfall, J; Parnell, C E; Oskoui, S Eradat

    2014-01-01

    While the exact acceleration mechanism of energetic particles during solar flares is (as yet) unknown, magnetic reconnection plays a key role both in the release of stored magnetic energy of the solar corona and the magnetic restructuring during a flare. Recent work has shown that special field lines, called separators, are common sites of reconnection in 3D numerical experiments. To date, 3D separator reconnection sites have received little attention as particle accelerators. We investigate the effectiveness of separator reconnection as a particle acceleration mechanism for electrons and protons. We study the particle acceleration using a relativistic guiding-centre particle code in a time-dependent kinematic model of magnetic reconnection at a separator. The effect upon particle behaviour of initial position, pitch angle and initial kinetic energy are examined in detail, both for specific (single) particle examples and for large distributions of initial conditions. The separator reconnection model contains ...

  8. High Gradient Accelerator Research

    Energy Technology Data Exchange (ETDEWEB)

    Temkin, Richard [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Physics. Plasma Science and Fusion Center

    2016-07-12

    The goal of the MIT program of research on high gradient acceleration is the development of advanced acceleration concepts that lead to a practical and affordable next generation linear collider at the TeV energy level. Other applications, which are more near-term, include accelerators for materials processing; medicine; defense; mining; security; and inspection. The specific goals of the MIT program are: • Pioneering theoretical research on advanced structures for high gradient acceleration, including photonic structures and metamaterial structures; evaluation of the wakefields in these advanced structures • Experimental research to demonstrate the properties of advanced structures both in low-power microwave cold test and high-power, high-gradient test at megawatt power levels • Experimental research on microwave breakdown at high gradient including studies of breakdown phenomena induced by RF electric fields and RF magnetic fields; development of new diagnostics of the breakdown process • Theoretical research on the physics and engineering features of RF vacuum breakdown • Maintaining and improving the Haimson / MIT 17 GHz accelerator, the highest frequency operational accelerator in the world, a unique facility for accelerator research • Providing the Haimson / MIT 17 GHz accelerator facility as a facility for outside users • Active participation in the US DOE program of High Gradient Collaboration, including joint work with SLAC and with Los Alamos National Laboratory; participation of MIT students in research at the national laboratories • Training the next generation of Ph. D. students in the field of accelerator physics.

  9. High Gradient Accelerator Research

    Energy Technology Data Exchange (ETDEWEB)

    Temkin, Richard [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Physics. Plasma Science and Fusion Center

    2016-07-12

    The goal of the MIT program of research on high gradient acceleration is the development of advanced acceleration concepts that lead to a practical and affordable next generation linear collider at the TeV energy level. Other applications, which are more near-term, include accelerators for materials processing; medicine; defense; mining; security; and inspection. The specific goals of the MIT program are: • Pioneering theoretical research on advanced structures for high gradient acceleration, including photonic structures and metamaterial structures; evaluation of the wakefields in these advanced structures • Experimental research to demonstrate the properties of advanced structures both in low power microwave cold test and high power, high gradient test at megawatt power levels • Experimental research on microwave breakdown at high gradient including studies of breakdown phenomena induced by RF electric fields and RF magnetic fields; development of new diagnostics of the breakdown process • Theoretical research on the physics and engineering features of RF vacuum breakdown • Maintaining and improving the Haimson / MIT 17 GHz accelerator, the highest frequency operational accelerator in the world, a unique facility for accelerator research • Providing the Haimson / MIT 17 GHz accelerator facility as a facility for outside users • Active participation in the US DOE program of High Gradient Collaboration, including joint work with SLAC and with Los Alamos National Laboratory; participation of MIT students in research at the national laboratories • Training the next generation of Ph. D. students in the field of accelerator physics.

  10. Centripetal Acceleration: Often Forgotten or Misinterpreted

    CERN Document Server

    Singh, Chandralekha

    2016-01-01

    Acceleration is a fundamental concept in physics which is taught in mechanics at all levels. Here, we discuss some challenges in teaching this concept effectively when the path along which the object is moving has a curvature and centripetal acceleration is present. We discuss examples illustrating that both physics teachers and students have difficulty with this concept. We conclude with instructional strategies that may help students with this challenging concept.

  11. Observation of Laser Wakefield Acceleration of Electrons

    CERN Document Server

    Amiranoff, F; Bernard, D; Cros, B; Descamps, D; Dorchies, F; Jacquet, F; Malka, V; Marqués, J R; Matthieussent, G; Miné, P; Modena, A; Mora, P; Morillo, J; Najmudin, Z

    1998-01-01

    The acceleration of electrons injected in a plasma wave generated by the laser wakefield mechanism has been observed. A maximum energy gain of 1.6~MeV has been measured and the maximum longitudinal electric field is estimated to 1.5~GV/m. The experimental data agree with theoretical predictions when 3D effects are taken into account. The duration of the plasma wave inferred from the number of accelerated electrons is of the order of 1~ps.

  12. Solar flare particle acceleration in collapsing magnetic traps

    OpenAIRE

    Grady, Keith J.

    2012-01-01

    The topic of this thesis is a detailed investigation of different aspects of the particle acceleration mechanisms operating in Collapsing Magnetic Traps (CMTs), which have been suggested as one possible mechanism for particle acceleration during solar flares. The acceleration processes in CMTs are investigated using guiding centre test particle calculations. Results including terms of different orders in the guiding centre approximation are compared to help identify which of the terms a...

  13. Pulsed Superconductivity Acceleration

    CERN Document Server

    Liepe, M

    2000-01-01

    The design of the proposed linear collider TESLA is based on 9-cell 1.3 GHz superconducting niobium cavities, operated in pulsed mode. Within the framework of an international collaboration the TESLA Test Facility (TTF) has been set up at DESY, providing the infrastructure for cavity R&D towards higher gradients. More than 60 nine-cell cavities were tested, accelerating gradients as high as 30 MV/m were measured. In the second production of TTF-cavities the average gradient was measured to be 24.7 MV/m. Two modules, each containing eight resonators, are presently used in the TTF-linac. These cavities are operated in pulsed mode: 0.8 ms constant gradient with up to 10 Hz repetitions rate. We will focus on two aspects: Firstly, the cavity fabrication and treatment is discussed, allowing to reach high gradients. Latest results of single cell cavities will be shown, going beyond 40 MV/m. Secondly, the pulsed mode operation of superconducting cavities is reviewed. This includes Lorentz force detuning, mechanic...

  14. Accelerator Modeling with MATLAB Accelerator Toolbox

    International Nuclear Information System (INIS)

    This paper introduces Accelerator Toolbox (AT)--a collection of tools to model storage rings and beam transport lines in the MATLAB environment. The objective is to illustrate the flexibility and efficiency of the AT-MATLAB framework. The paper discusses three examples of problems that are analyzed frequently in connection with ring-based synchrotron light sources

  15. Angular velocities, angular accelerations, and coriolis accelerations

    Science.gov (United States)

    Graybiel, A.

    1975-01-01

    Weightlessness, rotating environment, and mathematical analysis of Coriolis acceleration is described for man's biological effective force environments. Effects on the vestibular system are summarized, including the end organs, functional neurology, and input-output relations. Ground-based studies in preparation for space missions are examined, including functional tests, provocative tests, adaptive capacity tests, simulation studies, and antimotion sickness.

  16. Racetrack linear accelerators

    International Nuclear Information System (INIS)

    An improved recirculating electron beam linear accelerator of the racetrack type is described. The system comprises a beam path of four straight legs with four Pretzel bending magnets at the end of each leg to direct the beam into the next leg of the beam path. At least one of the beam path legs includes a linear accelerator. (UK)

  17. COLLECTIVE-FIELD ACCELERATION

    Energy Technology Data Exchange (ETDEWEB)

    Sessler, Andrew M.

    1969-07-04

    Diverse methods proposed for the acceleration of particles by means of collective fields are reviewed. A survey is made of the various currently active experimental programs devoted to investigating collective acceleration, and the present status of the research is briefly noted.

  18. KEK digital accelerator

    Science.gov (United States)

    Iwashita, T.; Adachi, T.; Takayama, K.; Leo, K. W.; Arai, T.; Arakida, Y.; Hashimoto, M.; Kadokura, E.; Kawai, M.; Kawakubo, T.; Kubo, Tomio; Koyama, K.; Nakanishi, H.; Okazaki, K.; Okamura, K.; Someya, H.; Takagi, A.; Tokuchi, A.; Wake, M.

    2011-07-01

    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.

  19. Asia honours accelerator physicists

    CERN Multimedia

    2010-01-01

    "Steve Meyers of Cern and Jie Wei of Beijing's Tsinghua University are the first recipients of a new prize for particle physics. The pair were honoured for their contributions to numerous particle-accelerator projects - including Cern's Large Hadron Collider - by the Asian Committee for Future Accelerators (ACFA)..." (1 paragraph)

  20. Accelerators for energy production

    International Nuclear Information System (INIS)

    A tremendous progress of accelerators for these several decades, has been motivated mainly by the research on subnuclear physics. The culmination in high energy accelerators might be SSC, 20 TeV collider in USA, probably the ultimate accelerator being built with the conventional principle. The technology cultivated and integrated for the accelerator development, can now stably offer the high power beam which could be used for the energy problems. The Inertial Confinement Fusion (ICF) with high current, 10 kA and short pulse, 20 ns heavy ion beam (HIB) of mass number ∼200, would be the most promising application of accelerators for energy production. In this scenario, the fuel containing D-T mixture, will be compressed to the high temperature, ∼10 keV and to the high density state, ∼1000 times the solid density with the pressure of ablative plasma or thermal X ray produced by bombarding of high power HIB. The efficiency, beam power/electric power for accelerator, and the repetition rate of HIB accelerators could be most suitable for the energy production. In the present paper, the outline of HIB ICF (HIF) is presented emphasizing the key issues of high current heavy ion accelerator system. (author)

  1. Accelerators Beyond The Tevatron?

    Energy Technology Data Exchange (ETDEWEB)

    Lach, Joseph; /Fermilab

    2010-07-01

    Following the successful operation of the Fermilab superconducting accelerator three new higher energy accelerators were planned. They were the UNK in the Soviet Union, the LHC in Europe, and the SSC in the United States. All were expected to start producing physics about 1995. They did not. Why?

  2. Maximal Acceleration Is Nonrotating

    CERN Document Server

    Page, D N

    1998-01-01

    In a stationary axisymmetric spacetime, the angular velocity of a stationary observer that Fermi-Walker transports its acceleration vector is also the angular velocity that locally extremizes the magnitude of the acceleration of such an observer, and conversely if the spacetime is also symmetric under reversing both t and phi together. Thus a congruence of Nonrotating Acceleration Worldlines (NAW) is equivalent to a Stationary Congruence Accelerating Locally Extremely (SCALE). These congruences are defined completely locally, unlike the case of Zero Angular Momentum Observers (ZAMOs), which requires knowledge around a symmetry axis. The SCALE subcase of a Stationary Congruence Accelerating Maximally (SCAM) is made up of stationary worldlines that may be considered to be locally most nearly at rest in a stationary axisymmetric gravitational field. Formulas for the angular velocity and other properties of the SCALEs are given explicitly on a generalization of an equatorial plane, infinitesimally near a symmetry...

  3. Linear induction accelerator

    International Nuclear Information System (INIS)

    This paper examines a new layout for the injector and accelerating sectins of a linear induction accelerator. The sections are combined in a single housing: an induction system with a current-pulse generator based on double strip shaping lines laid over ferromagnetic cores; a multichannel spark discharger with forced current division among channels; and a system for core demagnetization and electron-beam formation and transport. The results of formation of an electron beam in the injector system and its acceleration in the first accelerating section of the accelerator for injection of beams with energies of 0.2-0.4 MeV, currents of 1-2 kA, and pulse durations of 60 nsec are given

  4. Collinear wake field acceleration

    International Nuclear Information System (INIS)

    In the Voss-Weiland scheme of wake field acceleration a high current, ring-shaped driving bunch is used to accelerate a low current beam following along on axis. In such a structure, the transformer ratio, i.e., the ratio of maximum voltage that can be gained by the on-axis beam and the voltage lost by the driving beam, can be large. In contrast, it has been observed that for an arrangement in which driving and driven bunches follow the same path, and where the current distribution of both bunches is gaussian, the transformer ratio is not normally greater than two. This paper explores some of the possibilities and limitations of a collinear acceleration scheme. In addition to its application to wake field acceleration in structures, this study is also of interest for the understanding of the plasma wake field accelerator. 11 refs., 4 figs

  5. Accelerators, Beams And Physical Review Special Topics - Accelerators And Beams

    Energy Technology Data Exchange (ETDEWEB)

    Siemann, R.H.; /SLAC

    2011-10-24

    Accelerator science and technology have evolved as accelerators became larger and important to a broad range of science. Physical Review Special Topics - Accelerators and Beams was established to serve the accelerator community as a timely, widely circulated, international journal covering the full breadth of accelerators and beams. The history of the journal and the innovations associated with it are reviewed.

  6. Exploring Particle Acceleration in Gamma-Ray Binaries

    CERN Document Server

    Bosch-Ramon, V

    2011-01-01

    Binary systems can be powerful sources of non-thermal emission from radio to gamma rays. When the latter are detected, then these objects are known as gamma-ray binaries. In this work, we explore, in the context of gamma-ray binaries, different acceleration processes to estimate their efficiency: Fermi I, Fermi II, shear acceleration, the converter mechanism, and magnetic reconnection. We find that Fermi I acceleration in a mildly relativistic shock can provide, although marginally, the multi-10 TeV particles required to explain observations. Shear acceleration may be a complementary mechanism, giving particles the final boost to reach such a high energies. Fermi II acceleration may be too slow to account for the observed very high energy photons, but may be suitable to explain extended low-energy emission. The converter mechanism seems to require rather high Lorentz factors but cannot be discarded a priori. Standard relativistic shock acceleration requires a highly turbulent, weakly magnetized downstream med...

  7. 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 ...

  8. 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.

  9. Accelerator programme at CAT

    International Nuclear Information System (INIS)

    The Accelerator Programme at the Centre for Advanced Technology (CAT), Indore, has very broad based concept under which all types of accelerators are to be taken up for design and fabrication. This centre will be housing a wide variety of accelerators to serve as a common facility for the universities, national laboratories in addition to laboratories under the Department of Atomic Energy. In the first phase of the programme, a series of electron accelerators are designed and fabricated. They are synchrotron radiation sources of 450 MeV (INDUS-I) and of 2 GeV (INDUS-II), microtron upto energy of 20 MeV, linear accelerator upto 20 MeV, and DC Accelerator for industrial irradiation upto 750 KeV and 20 KW. A proton accelerator of 300 MeV with 20 MeV linac injector is also designed. CAT is also developing a strong base for support technologies like ultra high vacuum, radio frequency and microwaves, DC pulsed and superconducting magnets, power supplies and controls etc. These technologies are very useful for other industrial applications also. To develop user groups to utilise INDUS-II synchrotron radiation source, a batch production of rotating Anode X-ray generators with power supplies has been initiated. So also, the sputter ion pumps, electron guns, turbo molecular pumps are brought into batch production. (author)

  10. A cyclic behavior of CME accelerations for accelerating and decelerating events

    Institute of Scientific and Technical Information of China (English)

    Peng-Xin Gao; Ke-Jun Li

    2009-01-01

    We investigate the cyclic evolutionary behavior of CME accelerations for accelerating and decelerating CME events in cycle 23 from 1997 January to 2007 December.It is found that the absolute values of semiannual mean accelerations of both accelerating and decelerating CME events roughly wax and wane in a cycle,delaying the sunspot cycle in time phase.We also investigate the semiannual number of CMEs with positive and negative acceleration and find that there are more decelerating CME events than accelerating CME events during the maximum period of a cycle (about three years),but there are more accelerating CME events than decelerating CME events during the rest of the time interval of the cycle.Our results seem to suggest that the different driving mechanisms may be acting accelerate and decelerate CME events: for accelerating CME events,the propelling force (Fp) statistically seems to play a significant role in pushing CMEs outward;for decelerating CME events,the drag (F_d) statistically seems to play a more effective role in determining CME kinematic evolution in the outer corona.During the maximum period of a cycle,because of the V_2 dependence,Fd is generally stronger; because of the magnetic field dependence,Fp is also generally stronger.Thus,the absolute values of both the negative and positive accelerations are generally larger during that time.Because of the V2 dependence,Fd may be more effective during the maximum period of a cycle.Hence,there are more decelerating CME events than accelerating CME events during that time.During the minimum time interval of a cycle,CMEs have relatively small speeds,and Fp may be more effective.Therefore,there are more accelerating CME events than decelerating CME events during that time.

  11. 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 RE. 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 RE geocentric distance is less than 5 km s−1.

  12. Rf cavity primer for cyclic proton accelerators

    International Nuclear Information System (INIS)

    The purpose of this note is to describe the electrical and mechanical properites of particle accelerator rf cavities in a manner which will be useful to physics and engineering graduates entering the accelerator field. The discussion will be limited to proton (or antiproton) synchrotron accelerators or storage rings operating roughly in the range of 20 to 200 MHz. The very high gradient, fixed frequency UHF or microwave devices appropriate for electron machines and the somewhat lower frequency and broader bandwidth devices required for heavy ion accelerators are discussed extensively in other papers in this series. While it is common pratice to employ field calculation programs such as SUPERFISH, URMEL, or MAFIA as design aids in the development of rf cavities, we attempt here to elucidate various of the design parameters commonly dealt with in proton machines through the use of simple standing wave coaxial resonator expressions. In so doing, we treat only standing wave structures. Although low-impedance, moderately broad pass-band travelling wave accelerating systems are used in the CERN SPS, such systems are more commonly found in linacs, and they have not been used widely in large cyclic accelerators. Two appendices providing useful supporting material regarding relativistic particle dynamics and synchrotron motion in cyclic accelerators are added to supplement the text

  13. Accelerator Toolbox for MATLAB

    International Nuclear Information System (INIS)

    This paper introduces Accelerator Toolbox (AT)--a collection of tools to model particle accelerators and beam transport lines in the MATLAB environment. At SSRL, it has become the modeling code of choice for the ongoing design and future operation of the SPEAR 3 synchrotron light source. AT was designed to take advantage of power and simplicity of MATLAB--commercially developed environment for technical computing and visualization. Many examples in this paper illustrate the advantages of the AT approach and contrast it with existing accelerator code frameworks

  14. Hadron accelerators in medicine

    Energy Technology Data Exchange (ETDEWEB)

    Amaldi, U. [European Organization for Nuclear Research (CERN), Geneva (Switzerland). Accelerator School; Silari, M. [Consiglio Nazionale delle Ricerche, Milan (Italy)

    1996-12-31

    The application of hadron accelerators (protons and light ions) in cancer therapy is discussed. After a brief introduction on the rationale for the use of heavy charged particles in radiation therapy, a discussion is given on accelerator technology and beam delivery systems. Next, existing and planned facilities are briefly reviewed. The Italian Hadron-therapy Project is then described in some detail, with reference ro both the National Centre for Oncological Hadron-therapy and the design of different types of compact proton accelerators aimed at introducing proton therapy in a large umber of hospitals. (author) 28 refs.

  15. Confronting Twin Paradox Acceleration

    Science.gov (United States)

    Murphy, Thomas W.

    2016-05-01

    The resolution to the classic twin paradox in special relativity rests on the asymmetry of acceleration. Yet most students are not exposed to a satisfactory analysis of what exactly happens during the acceleration phase that results in the nonaccelerated observer's more rapid aging. The simple treatment presented here offers both graphical and quantitative solutions to the problem, leading to the correct result that the acceleration-induced age gap is 2Lβ years when the one-way distance L is expressed in light-years and velocity β ≡v/c .

  16. Entropic accelerating universe

    Energy Technology Data Exchange (ETDEWEB)

    Easson, Damien A., E-mail: easson@asu.ed [Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa, Chiba 277-8568 (Japan); Department of Physics and School of Earth and Space Exploration and Beyond Center, Arizona State University, Phoenix, AZ 85287-1504 (United States); Kavli Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106-4030 (United States); Frampton, Paul H., E-mail: frampton@physics.unc.ed [Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa, Chiba 277-8568 (Japan); Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC 27599 (United States); Smoot, George F., E-mail: gfsmoot@lbl.go [Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa, Chiba 277-8568 (Japan); Lawrence Berkeley National Lab, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Physics Department, University of California, Berkeley, CA 94720 (United States); Institute for the Early Universe, Ewha Womans University and Advanced Academy, Seoul (Korea, Republic of); Chaire Blaise Pascale, Universite Paris Denis Diderot, Paris (France)

    2011-01-31

    To accommodate the observed accelerated expansion of the universe, one popular idea is to invoke a driving term in the Friedmann-Lemaitre equation of dark energy which must then comprise 70% of the present cosmological energy density. We propose an alternative interpretation which takes into account the entropy and temperature intrinsic to the horizon of the universe due to the information holographically stored there. Dark energy is thereby obviated and the acceleration is due to an entropic force naturally arising from the information storage on the horizon surface screen. We consider an additional quantitative approach inspired by surface terms in general relativity and show that this leads to the entropic accelerating universe.

  17. ACCELERATORS: School prizes

    International Nuclear Information System (INIS)

    Dedicated to its goal of encouraging scientists and students to work in the field of particle accelerators, the US Particle Accelerator School (operating since 1981) has switched to a new format. Starting this year, it will offer in alternate years basic accelerator physics plus advanced subjects in both university and symposium styles over four weeks. Expanding the school from two to four weeks gives additional flexibility, and undergraduate participation should be encouraged by university credits being offered for particular courses. In the intervening years, the school will organize six-day topical courses

  18. Auroral electron acceleration

    International Nuclear Information System (INIS)

    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)

  19. The particle accelerator

    International Nuclear Information System (INIS)

    As the Palais de la Decouverte (in Paris) is the sole scientific vulgarization establishment in the world to operate an actual particle accelerator able to provoke different types of nuclear reactions, the author recalls some historical aspects of the concerned department since the creation of the 'Radioactivity - Atom synthesis' department in 1937. He recalls the experiments which were then performed, the installation of the particle accelerator in 1964 and its renewal. He describes what's going on in this accelerator. He gives an overview of the difficulties faced after it has been decided to move it, of the works which had to be performed, and of radiation protection measures

  20. Joint kinematics and kinetics of overground accelerated running versus running on an accelerated treadmill.

    Science.gov (United States)

    Caekenberghe, Ine Van; Segers, Veerle; Aerts, Peter; Willems, Patrick; De Clercq, Dirk

    2013-07-01

    Literature shows that running on an accelerated motorized treadmill is mechanically different from accelerated running overground. Overground, the subject has to enlarge the net anterior-posterior force impulse proportional to acceleration in order to overcome linear whole body inertia, whereas on a treadmill, this force impulse remains zero, regardless of belt acceleration. Therefore, it can be expected that changes in kinematics and joint kinetics of the human body also are proportional to acceleration overground, whereas no changes according to belt acceleration are expected on a treadmill. This study documents kinematics and joint kinetics of accelerated running overground and running on an accelerated motorized treadmill belt for 10 young healthy subjects. When accelerating overground, ground reaction forces are characterized by less braking and more propulsion, generating a more forward-oriented ground reaction force vector and a more forwardly inclined body compared with steady-state running. This change in body orientation as such is partly responsible for the changed force direction. Besides this, more pronounced hip and knee flexion at initial contact, a larger hip extension velocity, smaller knee flexion velocity and smaller initial plantarflexion velocity are associated with less braking. A larger knee extension and plantarflexion velocity result in larger propulsion. Altogether, during stance, joint moments are not significantly influenced by acceleration overground. Therefore, we suggest that the overall behaviour of the musculoskeletal system (in terms of kinematics and joint moments) during acceleration at a certain speed remains essentially identical to steady-state running at the same speed, yet acting in a different orientation. However, because acceleration implies extra mechanical work to increase the running speed, muscular effort done (in terms of power output) must be larger. This is confirmed by larger joint power generation at the level of

  1. Particle Acceleration in 3D Magnetic Reconnection

    Science.gov (United States)

    Dahlin, J.; Drake, J. F.; Swisdak, M.

    2015-12-01

    Magnetic reconnection is an important driver of energetic particles in phenomena such as magnetospheric storms and solar flares. Using kinetic particle-in-cell (PIC) simulations, we show that the stochastic magnetic field structure which develops during 3D reconnection plays a vital role in particle acceleration and transport. In a 2D system, electrons are trapped in magnetic islands which limits their energy gain. In a 3D system, however, the stochastic magnetic field enables the energetic electrons to access volume-filling acceleration regions and therefore gain energy much more efficiently than in the 2D system. We also examine the relative roles of two important acceleration drivers: parallel electric fields and a Fermi mechanism associated with reflection of charged particles from contracting field lines. We find that parallel electric fields are most important for accelerating low energy particles, whereas Fermi reflection dominates energetic particle production. We also find that proton energization is reduced in the 3D system.

  2. SPS accelerating cavity

    CERN Multimedia

    1983-01-01

    See photo 8202397: View towards the downstream end of one of the SPS accelerating cavities (200 MHz, travelling wave structure). See 7603195 and 8011289 for more details, 7411032 for the travelling wave structure, and also 8104138.

  3. SPS accelerating cavity

    CERN Multimedia

    1983-01-01

    View towards the downstream end of one of the SPS accelerating cavities (200 MHz, travelling wave structure). See 7603195 and 8011289 for more details, 7411032 for the travelling wave structure, and also 8104138.

  4. Rejuvenating CERN's Accelerators

    CERN Multimedia

    2004-01-01

    In the coming years and especially in 2005, CERN's accelerators are going to receive an extensive renovation programme to ensure they will perform reliably and effectively when the LHC comes into service.

  5. Dimension Driven Accelerating Universe

    CERN Document Server

    Chatterjee, S

    2009-01-01

    The current acceleration of the universe leads us to investigate higher dimensional gravity theory, which is able to explain acceleration from a theoretical view point without the need of introducing dark energy by hand. We argue that the terms containing higher dimensional metric coefficients produce an extra negative pressure that apparently drives an acceleration of the 3D space, tempting us to suggest that the accelerating universe seems to act as a window to the existence of extra spatial dimensions. Interesting to point out that in this case our cosmology apparently mimics the well known quintessence scenario fuelled by a generalised Chaplygin-type of fluid where a smooth transition from a dust dominated model to a de Sitter like one takes place. Correspondence to models generated by a tachyonic form of matter is also briefly discussed.

  6. Joint International Accelerator School

    CERN Multimedia

    CERN Accelerator School

    2014-01-01

    The CERN and US Particle Accelerator Schools recently organised a Joint International Accelerator School on Beam Loss and Accelerator Protection, held at the Hyatt Regency Hotel, Newport Beach, California, USA from 5-14 November 2014. This Joint School was the 13th in a series of such schools, which started in 1985 and also involves the accelerator communities in Japan and Russia.   Photo courtesy of Alfonse Pham, Michigan State University.   The school attracted 58 participants representing 22 different nationalities, with around half from Europe and the other half from Asia and the Americas. The programme comprised 26 lectures, each of 90 minutes, and 13 hours of case study. The students were given homework each day and had an opportunity to sit a final exam, which counted towards university credit. Feedback from the participants was extremely positive, praising the expertise and enthusiasm of the lecturers, as well as the high standard and quality of their lectures. Initial dis...

  7. A symmetrical rail accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Igenbergs, E. (Technische Univ. Muenchen, Lehrstuhl fuer Raumfahrttechnik, Richard-Wagner-Strasse 18, 8000 Muenchen 2 (DE))

    1991-01-01

    This paper reports on the symmetrical rail accelerator that has four rails, which are arranged symmetrically around the bore. The opposite rails have the same polarity and the adjacent rails the opposite polarity. In this configuration the radial force acting upon the individual rails is significantly smaller than in a conventional 2-rail configuration and a plasma armature is focussed towards the axis of the barrel. Experimental results indicate a higher efficiency compared to a conventional rail accelerator.

  8. Advanced Accelerator Concepts

    International Nuclear Information System (INIS)

    This conference proceedings represent the results of theThird Advanced Accelerator Concepts Workshop held in PortJefferson, New York. The workshop was sponsored by the U.S.Department of Energy, the Office of Navel Research and BrookhavenNational Laboratory. The purpose was to assess new techniques forproduction of ultra-high gradient acceleration and to addressengineering issues in achieving this goal. There are eighty-onepapers collected in the proceedings and all have been abstractedfor the database

  9. CEBAF Accelerator Achievements

    International Nuclear Information System (INIS)

    In the past decade, nuclear physics users of Jefferson Lab's Continuous Electron Beam Accelerator Facility (CEBAF) have benefited from accelerator physics advances and machine improvements. As of early 2011, CEBAF operates routinely at 6 GeV, with a 12 GeV upgrade underway. This article reports highlights of CEBAF's scientific and technological evolution in the areas of cryomodule refurbishment, RF control, polarized source development, beam transport for parity experiments, magnets and hysteresis handling, beam breakup, and helium refrigerator operational optimization.

  10. Accelerating Cosmologies from Compactification

    CERN Document Server

    Townsend, P K; Townsend, Paul K.; Wohlfarth, Mattias N.R.

    2003-01-01

    A solution of the (4+n)-dimensional vacuum Einstein equations is found for which spacetime is compactified on a compact hyperbolic manifold of time-varying volume to a flat four-dimensional FLRW cosmology undergoing accelerated expansion in Einstein conformal frame. This shows that the `no-go' theorem forbidding acceleration in `standard' (time-independent) compactifications of string/M-theory does not apply to `cosmological' (time-dependent) hyperbolic compactifications.

  11. Designing reliability into accelerators

    International Nuclear Information System (INIS)

    Future accelerators will have to provide a high degree of reliability. Quality must be designed in right from the beginning and must remain a central theme throughout the project. The problem is similar to the problems facing US industry today, and examples of the successful application of quality engineering will be given. Different aspects of an accelerator project will be addressed: Concept, Design, Motivation, Management Techniques, and Fault Diagnosis. The importance of creating and maintaining a coherent team will be stressed

  12. Accelerated cyclic corrosion tests

    OpenAIRE

    Prošek T.

    2016-01-01

    Accelerated corrosion testing is indispensable for material selection, quality control and both initial and residual life time prediction for bare and painted metallic, polymeric, adhesive and other materials in atmospheric exposure conditions. The best known Neutral Salt Spray (NSS) test provides unrealistic conditions and poor correlation to exposures in atmosphere. Modern cyclic accelerated corrosion tests include intermittent salt spray, wet and dry phases and eventually other technical p...

  13. Accelerating News Issue 2

    CERN Document Server

    Kahle, K; Wildner, E

    2012-01-01

    In this summer issue we look at how developments in collimator materials could have applications in aerospace and beyond, and how Polish researchers are harnessing accelerators for medical and industrial uses. We see how the LHC luminosity upgrade is linking with European industry and US researchers, and how the neutrino oscillation community is progressing. We find out the mid-term status of TIARA-PP and how it is mapping European accelerator education resources.

  14. Nuclear physics accelerator facilities

    International Nuclear Information System (INIS)

    Brief descriptions are given of DOE and Nuclear Physics program operated and sponsored accelerator facilities. Specific facilities covered are the Argonne Tandem/Linac Accelerator System, the Tandem/AGS Heavy Ion Facility at Brookhaven National Laboratory, the proposed Continuous Beam Accelerator at Newport News, Virginia, the Triangle Universities Nuclear Laboratory at Duke University, the Bevalac and the SuperHILAC at Lawrence Berkeley Laboratory, the 88-Inch Cyclotron at Lawrence Berkeley Laboratory, the Clinton P. Anderson Meson Physics Facility at Los Alamos National Laboratory, the Bates Linear Accelerator Center at Massachusetts Institute of Technology, the Holifield Heavy Ion Research Facility at Oak Ridge National Laboratory, the Nuclear Physics Injector at Stanford Linear Accelerator Center, the Texas A and M Cyclotrons, the Tandem/Superconducting Booster Accelerator at the University of Washington and the Tandem Van de Graaff at the A.W. Wright Nuclear Structure Laboratory of Yale University. Included are acquisition cost, research programs, program accomplishments, future directions, and operating parameters of each facility

  15. Accelerators for America's Future

    Science.gov (United States)

    Bai, Mei

    2016-03-01

    Particle accelerator, a powerful tool to energize beams of charged particles to a desired speed and energy, has been the working horse for investigating the fundamental structure of matter and fundermental laws of nature. Most known examples are the 2-mile long Stanford Linear Accelerator at SLAC, the high energy proton and anti-proton collider Tevatron at FermiLab, and Large Hadron Collider that is currently under operation at CERN. During the less than a century development of accelerator science and technology that led to a dazzling list of discoveries, particle accelerators have also found various applications beyond particle and nuclear physics research, and become an indispensible part of the economy. Today, one can find a particle accelerator at almost every corner of our lives, ranging from the x-ray machine at the airport security to radiation diagnostic and therapy in hospitals. This presentation will give a brief introduction of the applications of this powerful tool in fundermental research as well as in industry. Challenges in accelerator science and technology will also be briefly presented

  16. 单进口后混式射流粉碎中多相流混合机理及加速特性%Mixing mechanism of multiphase flow and acceleration performance in single inlet rear-mixed jet flow crushing

    Institute of Scientific and Technical Information of China (English)

    万继伟; 牛争鸣; 廖伟丽; 牛助农

    2013-01-01

    In order to deeply understand the super fine crushing technology of rear-mixed high-speed water jet flow,the mixing and jetting behavior of gas-liquid-solid three phases in acceleration tube with various diameter were investigated by using numerical simulation and crushing experiment methods.Mixing mechanism and acceleration performance of multiphase mixture jet flow were explored,and particles distributions in acceleration space were obtained.The result showed that aeration and entrainment effects of jet flow turbulent motion were the inherent mechanism of mixed attached phase.There existed many partition zones in the rear-mixed jet flow for particle acceleration.Whereby the nearer to the potential flow zone,the stronger the impact energy.Accordingly,optimizing configuration of the optional nozzle diameter with the acceleration tube diameter could force the particles near or enter the potential flow zone,whereby effectively improving grinding yield efficiency.The particles in space distribution within the acceleration tube were in the highest contents in high-efficiency acceleration zones of the outer and inner layers.As a result,the nearer to the potential flow zone,the fewer the particles.The particle contents in the air flow zone increased with increasing acceleration tube diameter.It was difficult for the particles to enter the ideal acceleration zone so that most of the particles were accelerated by relying on the highefficiency acceleration zone of the inner and outer layers.In the case of maintaining the flowing morphological state of free jet flow,the grinding yield efficiency decreased with increasing acceleration tube diameter.Accordingly small tube diameter was of better constraint and concentration functions for water jet flow energy and particle motion space.%为了深入了解后混式高速水射流超细粉碎技术,以4种加速管管径条件下的液、气、固三相混合射流为对象,利用数值计算和粉碎实验相结合的方法,研

  17. Particle acceleration by combined diffusive shock acceleration and downstream multiple magnetic island acceleration

    Science.gov (United States)

    Zank, G. P.; Hunana, P.; Mostafavi, P.; le Roux, J. A.; Li, Gang; Webb, G. M.; Khabarova, O.

    2015-09-01

    As a consequence of the evolutionary conditions [28; 29], shock waves can generate high levels of downstream vortical turbulence. Simulations [32-34] and observations [30; 31] support the idea that downstream magnetic islands (also called plasmoids or flux ropes) result from the interaction of shocks with upstream turbulence. Zank et al. [18] speculated that a combination of diffusive shock acceleration (DSA) and downstream reconnection-related effects associated with the dynamical evolution of a “sea of magnetic islands” would result in the energization of charged particles. Here, we utilize the transport theory [18; 19] for charged particles propagating diffusively in a turbulent region filled with contracting and reconnecting plasmoids and small-scale current sheets to investigate a combined DSA and downstream multiple magnetic island charged particle acceleration mechanism. We consider separately the effects of the anti-reconnection electric field that is a consequence of magnetic island merging [17], and magnetic island contraction [14]. For the merging plasmoid reconnection- induced electric field only, we find i) that the particle spectrum is a power law in particle speed, flatter than that derived from conventional DSA theory, and ii) that the solution is constant downstream of the shock. For downstream plasmoid contraction only, we find that i) the accelerated particle spectrum is a power law in particle speed, flatter than that derived from conventional DSA theory; ii) for a given energy, the particle intensity peaks downstream of the shock, and the peak location occurs further downstream of the shock with increasing particle energy, and iii) the particle intensity amplification for a particular particle energy, f(x, c/c0)/f(0, c/c0), is not 1, as predicted by DSA theory, but increases with increasing particle energy. These predictions can be tested against observations of electrons and ions accelerated at interplanetary shocks and the heliospheric

  18. Effect of Accelerated Ultraviolet Aging on Mechanical Properties of Polyethylene Film%加速紫外老化对聚乙烯薄膜力学性能的影响

    Institute of Scientific and Technical Information of China (English)

    姚培培; 李琛

    2013-01-01

    The aging principle of polyethylene (PE) film was introduced, and the accelerated ultraviolet aging experiments of PE film were carried on. Setting the cycle way of ultraviolet irradiation and gel and spray, in order to test the changes of the mechanical properties of PE film before and after the aging test, and also define the influence on the PE properties as the aging time extended. The results show that: the PE chemical bond triggers cross linking and cleavage reaction under the ultraviolet irradiation, cleavage reaction occupies a predominant position to lead to polymer molecular weight decrease. The tensile strength and breaking elongation rate and elastic modulus of PE film all reduce with the aging time extended. The force to resist destruction of PE film occur to decline sharply after aging 60 hours, at the same time the elastic modulus trends to slow down, the breaking elongation rate is nearly linear as the ageing time to decrease.%介绍了聚乙烯(PE)薄膜老化机理,并对PE薄膜进行了人工加速紫外光老化试验.分析了老化时间对PE薄质力学性能的影响.结果表明:紫外光的照射使PE的化学键发生交联和断裂反应,其中断裂反应占主导,使聚合物分子量减小,物理性能下降;PE薄膜的拉伸强度,断裂伸长率和弹性模量随老化时间的延长而降低;PE薄膜抵抗破坏的能力在老化60 h以上会急剧下降,而此时弹性模量的变化趋势变得平缓,断裂伸长率与老化时间近似成线性关系递减.

  19. Small type accelerator. Try for accelerator driven system

    CERN Document Server

    Mori, Y

    2003-01-01

    FFAG (Fixed-field alternating gradient) accelerator for accelerator driven subcritical reactor, which aims to change from long-lived radioactive waste to short-lived radioactivity, is introduced. It is ring accelerator. The performance needed is proton as accelerator particle, 10MW (total) beam power, about 1GeV beam energy, >30% power efficiency and continuous beam. The feature of FFAG accelerator is constant magnetic field. PoP (Proof-of-principle)-FFAG accelerator, radial type, was run at first in Japan in 2000. The excursion is about some ten cm. In principle, beam can be injected and extracted at any place of ring. The 'multi-fish' acceleration can accelerate beams to 100% duty by repeating acceleration. 150MeV-FFAG accelerator has been started since 2001. It tried to practical use, for example, treatment of cancer. (S.Y.)

  20. Educating and Training Accelerator Scientists and Technologists for Tomorrow

    CERN Document Server

    Barletta, William A; Seryi, Andrei

    2012-01-01

    Accelerator science and technology is inherently an integrative discipline that combines aspects of physics, computational science, electrical and mechanical engineering. As few universities offer full academic programs, the education of accelerator physicists and engineers for the future has primarily relied on a combination of on-the-job training supplemented with intense courses at regional accelerator schools. This paper describes the approaches being used to satisfy the educational interests of a growing number of interested physicists and engineers.

  1. The Study of Expert System Utilization for the Accelerator Operation

    International Nuclear Information System (INIS)

    The utilization of expert system in the accelerator laboratory has been studied. The study covers the utilization of expert system in the setting up experiment (tuning parameter), controlling system, safety or warning system. The results study shows, that using the expert system in the accelerator would be easy to operate the accelerator for user and operator. Increasing the skill of expert system could be updated without logical mechanism modification. (author)

  2. Linear collider accelerator physics issues regarding alignment

    International Nuclear Information System (INIS)

    The next generation of linear colliders will require more stringent alignment tolerances than those for the SLC with regard to the accelerating structures, quadrupoles, and beam position monitors. New techniques must be developed to achieve these tolerances. A combination of mechanical-electrical and beam-based methods will likely be needed

  3. Accelerating nondiffracting beams

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Shaohui; Li, Manman; Yao, Baoli, E-mail: yaobl@opt.ac.cn; Yu, Xianghua; Lei, Ming; Dan, Dan; Yang, Yanlong; Min, Junwei; Peng, Tong

    2015-06-05

    We present a set of beams which combine the properties of accelerating beams and (conventional) diffraction-free beams. These beams can travel along a desired trajectory while keeping an approximately invariant transverse profile, which may be (higher-order) Bessel-, Mathieu- or parabolic-nondiffracting-like beams, depending on the initial complex amplitude distribution. A possible application of these beams presented here may be found in optical trapping field. For example, a higher-order Bessel-like beam, which has a hollow (transverse) pattern, is suitable for guiding low-refractive-index or metal particles along a curve. - Highlights: • A set of beams having arbitrary trajectories of accelerating and nondiffracting behaviors are generalized and presented. • Bessel-like accelerating beams are generalized to the higher-order (hollow) version. • Mathieu-like accelerating beams and parabolic-nondiffracting-like accelerating beams are presented. • A possible application of these beams may be found in optical trapping and guiding of particles.

  4. Dielectric laser accelerators

    Science.gov (United States)

    England, R. Joel; Noble, Robert J.; Bane, Karl; Dowell, David H.; Ng, Cho-Kuen; Spencer, James E.; Tantawi, Sami; Wu, Ziran; Byer, Robert L.; Peralta, Edgar; Soong, Ken; Chang, Chia-Ming; Montazeri, Behnam; Wolf, Stephen J.; Cowan, Benjamin; Dawson, Jay; Gai, Wei; Hommelhoff, Peter; Huang, Yen-Chieh; Jing, Chunguang; McGuinness, Christopher; Palmer, Robert B.; Naranjo, Brian; Rosenzweig, James; Travish, Gil; Mizrahi, Amit; Schachter, Levi; Sears, Christopher; Werner, Gregory R.; Yoder, Rodney B.

    2014-10-01

    The use of infrared lasers to power optical-scale lithographically fabricated particle accelerators is a developing area of research that has garnered increasing interest in recent years. The physics and technology of this approach is reviewed, which is referred to as dielectric laser acceleration (DLA). In the DLA scheme operating at typical laser pulse lengths of 0.1 to 1 ps, the laser damage fluences for robust dielectric materials correspond to peak surface electric fields in the GV /m regime. The corresponding accelerating field enhancement represents a potential reduction in active length of the accelerator between 1 and 2 orders of magnitude. Power sources for DLA-based accelerators (lasers) are less costly than microwave sources (klystrons) for equivalent average power levels due to wider availability and private sector investment. Because of the high laser-to-particle coupling efficiency, required pulse energies are consistent with tabletop microJoule class lasers. Combined with the very high (MHz) repetition rates these lasers can provide, the DLA approach appears promising for a variety of applications, including future high-energy physics colliders, compact light sources, and portable medical scanners and radiative therapy machines.

  5. Laser technologies for laser accelerators. Annual report

    International Nuclear Information System (INIS)

    The primary result of the work reported is the determination of laser system architectures that satsify the requirements of high luminosity, high energy (about 1 TeV), electron accelerators. It has been found that high laser efficiency is a very hard driver for these accelerators as the total average laser output optical power is likely to fall above 10 MW. The luminosity requires rep rates in the kHz range, and individual pulse lengths in the 1-10 psec range are required to satisfy acceleration gradient goals. CO2 and KrF lasers were chosen for study because of their potential to simultaneously satisfy the given requirements. Accelerator luminosity is reviewed, and requirements on laser system average power and rep rate are determined as a function of electron beam bunch parameters. Laser technologies are reviewed, including CO2, excimers, solid state, and free electron lasers. The proposed accelerator mechanisms are summarized briefly. Work on optical transport geometries for near and far field accelerators are presented. Possible exploitation of the CO2 and DrF laser technology to generate the required pulse lengths, rep rates, and projected efficiencies is illustrated and needed development work is suggested. Initial efforts at developing a 50 GeV benchmark conceptual design and a 100 MeV demonstration experiment conceptual design are presented

  6. Plasma-based accelerator structures

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, Carl B.

    1999-12-01

    Plasma-based accelerators have the ability to sustain extremely large accelerating gradients, with possible high-energy physics applications. This dissertation further develops the theory of plasma-based accelerators by addressing three topics: the performance of a hollow plasma channel as an accelerating structure, the generation of ultrashort electron bunches, and the propagation of laser pulses is underdense plasmas.

  7. Plasma-based accelerator structures

    International Nuclear Information System (INIS)

    Plasma-based accelerators have the ability to sustain extremely large accelerating gradients, with possible high-energy physics applications. This dissertation further develops the theory of plasma-based accelerators by addressing three topics: the performance of a hollow plasma channel as an accelerating structure, the generation of ultrashort electron bunches, and the propagation of laser pulses is underdense plasmas

  8. Particle accelerator physics

    CERN Document Server

    Wiedemann, Helmut

    2007-01-01

    Particle Accelerator Physics is an in-depth and comprehensive introduction to the field of high-energy particle acceleration and beam dynamics. Part I gathers the basic tools, recalling the essentials of electrostatics and electrodynamics as well as of particle dynamics in electromagnetic fields. Part II is an extensive primer in beam dynamics, followed in Part III by the introduction and description of the main beam parameters. Part IV is devoted to the treatment of perturbations in beam dynamics. Part V discusses the details of charged particle accleration. Part VI and Part VII introduce the more advanced topics of coupled beam dynamics and the description of very intense beams. Part VIII is an exhaustive treatment of radiation from accelerated charges and introduces important sources of coherent radiation such as synchrotrons and free-electron lasers. Part IX collects the appendices gathering useful mathematical and physical formulae, parameters and units. Solutions to many end-of-chapter problems are give...

  9. Superconducting Accelerator Magnets

    CERN Document Server

    Mess, K H; Wolff, S

    1996-01-01

    The main topic of the book are the superconducting dipole and quadrupole magnets needed in high-energy accelerators and storage rings for protons, antiprotons or heavy ions. The basic principles of low-temperature superconductivity are outlined with special emphasis on the effects which are relevant for accelerator magnets. Properties and fabrication methods of practical superconductors are described. Analytical methods for field calculation and multipole expansion are presented for coils without and with iron yoke. The effect of yoke saturation and geometric distortions on field quality is studied. Persistent magnetization currents in the superconductor and eddy currents the copper part of the cable are analyzed in detail and their influence on field quality and magnet performance is investigated. Superconductor stability, quench origins and propagation and magnet protection are addressed. Some important concepts of accelerator physics are introduced which are needed to appreciate the demanding requirements ...

  10. Uniform Acceleration in General Relativity

    CERN Document Server

    Friedman, Yaakov

    2016-01-01

    We extend de la Fuente and Romero's defining equation for uniform acceleration in a general curved spacetime from linear acceleration to the full Lorentz covariant uniform acceleration. In a flat spacetime background, we have explicit solutions. We use generalized Fermi-Walker transport to parallel transport the Frenet basis along the trajectory. In flat spacetime, we obtain velocity and acceleration transformations from a uniformly accelerated system to an inertial system. We obtain the time dilation between accelerated clocks. We apply our acceleration transformations to the motion of a charged particle in a constant electromagnetic field and recover the Lorentz-Abraham-Dirac equation.

  11. Nuclear Physics accelerator facilities

    International Nuclear Information System (INIS)

    The Nuclear Physics program requires the existence and effective operation of large and complex accelerator facilities. These facilities provide the variety of projectile beams upon which virtually all experimental nuclear research depends. Their capability determine which experiments can be performed and which cannot. Seven existing accelerator facilities are operated by the Nuclear Physics program as national facilities. These are made available to all the Nation's scientists on the basis of scientific merit and technical feasibility of proposals. The national facilities are the Clinton P. Anderson Meson Physics Facility (LAMPF) at Los Alamos National Laboratory; the Bates Linear Accelerator Center at Massachusetts Institute of Technology; the Bevalac at Lawrence Berkeley Laboratory; the Tandem/AGS Heavy Ion Facility at Brookhaven National Laboratory; the ATLAS facility at Argonne National Laboratory; the 88-Inch Cyclotron at Lawrence Berkeley Laboratory; the Holifield Heavy Ion Research Facility at Oak Ridge National Laboratory. The Nuclear Physics Injector at the Stanford Linear Accelerator Center (SLAC) enables the SLAC facility to provide a limited amount of beam time for nuclear physics research on the same basis as the other national facilities. To complement the national facilities, the Nuclear Physics program supports on-campus accelerators at Duke University, Texas A and M University, the University of Washington, and Yale University. The facility at Duke University, called the Triangle Universities Nuclear Laboratory (TUNL), is jointly staffed by Duke University, North Carolina State University, and the University of North Carolina. These accelerators are operated primarily for the research use of the local university faculty, junior scientists, and graduate students

  12. Microelectromechanical acceleration-sensing apparatus

    Science.gov (United States)

    Lee, Robb M.; Shul, Randy J.; Polosky, Marc A.; Hoke, Darren A.; Vernon, George E.

    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.

  13. Studies of accelerated compact toruses

    International Nuclear Information System (INIS)

    In an earlier publication we considered acceleration of plasma rings (Compact Torus). Several possible accelerator configurations were suggested and the possibility of focusing the accelerated rings was discussed. In this paper we consider one scheme, acceleration of a ring between coaxial electrodes by a B/sub theta/ field as in a coaxial rail-gun. If the electrodes are conical, a ring accelerated towards the apex of the cone undergoes self-similar compression (focusing) during acceleration. Because the allowable acceleration force, F/sub a/ = kappaU/sub m//R where (kappa -2, the accelerating distance for conical electrodes is considerably shortened over that required for coaxial electrodes. In either case, however, since the accelerating flux can expand as the ring moves, most of the accelerating field energy can be converted into kinetic energy of the ring leading to high efficiency

  14. Intermittent Sea Level Acceleration

    OpenAIRE

    Olivieri, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Spada, G.; Dipartimento di Scienze di Base e Fondamenti, Università di Urbino Carlo Bo, Urbino

    2013-01-01

    Using instrumental observations from the Permanent Service for Mean Sea Level (PSMSL), we provide a new assessment of the global sea{level acceleration for the last 2 centuries (1820-2010). Our results, obtained by a stack of tide gauge time series, con firm the existence of a global sea level acceleration (GSLA) and, coherently with independent assessments so far, they point to a value close to 0:01 mm/yr2. However, di fferently from previous studies, we discuss how change points or ...

  15. Seismic surveying and accelerators

    International Nuclear Information System (INIS)

    The paper deals with an investigation into the impact of earth vibrations on charged particle beams in modern colliders. It is ascertained that the displacement of accelerator magnetic elements from the perfect position results in the excitation of betatron oscillations and distortion of particle orbit position. The results of experimental investigations into seismic noises are presented for ASR, SSC, DESY and KEK. The rms orbit displacement in accelerators is estimated relying on the law of earth diffusion motion, according to which the variance of relative displacements is proportional to the distance between these points and time of observation. 6 refs., 3 figs., 2 tabs

  16. High intensity hadron accelerators

    International Nuclear Information System (INIS)

    This rapporteur report consists mainly of two parts. Part I is an abridged review of the status of all High Intensity Hadron Accelerator projects in the world in semi-tabulated form for quick reference and comparison. Part II is a brief discussion of the salient features of the different technologies involved. The discussion is based mainly on my personal experiences and opinions, tempered, I hope, by the discussions I participated in in the various parallel sessions of the workshop. In addition, appended at the end is my evaluation and expression of the merits of high intensity hadron accelerators as research facilities for nuclear and particle physics

  17. SPS accelerating cavity

    CERN Multimedia

    1983-01-01

    See photo 8302397: View from the downstream end of one of the SPS accelerating cavities (200 MHz, travelling wave structure). See 7603195 and 8011289 for more details, 7411032 for the travelling wave structure, and also 8104138. Giacomo Primadei stands on the left.

  18. The CERN accelerator complex

    CERN Multimedia

    Haffner, Julie

    2013-01-01

    The LHC is the last ring (dark grey line) in a complex chain of particle accelerators. The smaller machines are used in a chain to help boost the particles to their final energies and provide beams to a whole set of smaller experiments, which also aim to uncover the mysteries of the Universe.

  19. Hamburg Accelerator Conference

    International Nuclear Information System (INIS)

    From 20-24 July, Hamburg welcomed the Fifteenth International Conference on High Energy Accelerators (HEACC). A natural highlight was the recent commissioning success of the HERA electron-proton collider at Hamburg's DESY Laboratory and its first high energy electron-proton collision data. This gave the meeting the feel of a family event celebrating a newborn

  20. The CERN accelerator complex

    CERN Multimedia

    Christiane Lefèvre

    2008-01-01

    The LHC is the last ring (dark grey line) in a complex chain of particle accelerators. The smaller machines are used in a chain to help boost the particles to their final energies and provide beams to a whole set of smaller experiments, which also aim to uncover the mysteries of the Universe.

  1. The CERN accelerator complex

    CERN Multimedia

    De Melis, Cinzia

    2016-01-01

    The LHC is the last ring (dark blue line) in a complex chain of particle accelerators. The smaller machines are used in a chain to help boost the particles to their final energies and provide beams to a whole set of smaller experiments, which also aim to uncover the mysteries of the Universe.

  2. The Bevalac accelerator

    International Nuclear Information System (INIS)

    Presented are the characteristics of the Bevatron and SuperHilac heavy ion accelerators in a very general manner. Some aspects of their application in the field of biological medicine and some of the interesting results obtained in experiments on nuclear physics are mentioned. (Author). 20 refs, 2 figs, 2 tabs

  3. The CERN Accelerator School

    CERN Multimedia

    2016-01-01

      Introduction to accelerator physics This course will take place in Istanbul, Turkey, from 18 to 30 September 2016. It is now open for registration, and further information can be found here: http://cas.web.cern.ch/cas/Turkey-2016/Turkey-advert.html

  4. SPS accelerating cavity

    CERN Multimedia

    1980-01-01

    One of the SPS acceleration cavities (200 MHz, travelling wave structure). On the ceiling one sees the coaxial transmission line which feeds the power from the amplifier, located in a surface building above, to the upstream end of the cavity. See 7603195 for more details, 7411032 for the travelling wave structure, and also 8104138, 8302397.

  5. Prospects for Accelerator Technology

    Science.gov (United States)

    Todd, Alan

    2011-02-01

    Accelerator technology today is a greater than US$5 billion per annum business. Development of higher-performance technology with improved reliability that delivers reduced system size and life cycle cost is expected to significantly increase the total accelerator technology market and open up new application sales. Potential future directions are identified and pitfalls in new market penetration are considered. Both of the present big market segments, medical radiation therapy units and semiconductor ion implanters, are approaching the "maturity" phase of their product cycles, where incremental development rather than paradigm shifts is the norm, but they should continue to dominate commercial sales for some time. It is anticipated that large discovery-science accelerators will continue to provide a specialty market beset by the unpredictable cycles resulting from the scale of the projects themselves, coupled with external political and economic drivers. Although fraught with differing market entry difficulties, the security and environmental markets, together with new, as yet unrealized, industrial material processing applications, are expected to provide the bulk of future commercial accelerator technology growth.

  6. Heavy ion accelerator GANIL

    International Nuclear Information System (INIS)

    This article presents GANIL, a large national heavy ion accelerator. The broad problems of nuclear physics, atomic physics, astrophysics and physics of condensed media which can be approached and studied with this machine are discussed first, after which the final construction project is described. The project comprises a circular injector, a separated sector cyclotron up beam stripper, and a second separated cyclotron downstream

  7. Superconducting traveling wave accelerators

    International Nuclear Information System (INIS)

    This note considers the applicability of superconductivity to traveling wave accelerators. Unlike CW operation of a superconducting standing wave or circulating wave accelerator section, which requires improvement factors (superconductor conductivity divided by copper conductivity) of about 106 in order to be of practical use, a SUperconducting TRaveling wave Accelerator, SUTRA, operating in the pulsed mode requires improvement factors as low as about 103, which are attainable with niobium or lead at 4.2K, the temperature of liquid helium at atmospheric pressure. Changing from a copper traveling wave accelerator to SUTRA achieves the following. (1) For a given gradient SUTRA reduces the peak and average power requirements typically by a factor of 2. (2) SUTRA reduces the peak power still further because it enables us to increase the filling time and thus trade pulse width for gradient. (3) SUTRA makes possible a reasonably long section at higher frequencies. (4) SUTRA makes possible recirculation without additional rf average power. 8 references, 6 figures, 1 table

  8. SPS accelerating cavity

    CERN Multimedia

    CERN PhotoLab

    1981-01-01

    One of the SPS accelerating cavities (200 MHz, travelling wave structure). The power that is fed into the upstream end of the cavity is extracted at the downstream end and sent into a dump load. See 7603195 for more details, 7411032 for the travelling wave structure, and also 8011289, 8302397.

  9. The CERN Accelerator School

    CERN Multimedia

    2016-01-01

    Introduction to accelerator physics This course will take place in Budapest, Hungary, from 2 to 14 October 2016. It is now open for registration and further information can be found at: http://cas.web.cern.ch/cas/Hungary2016/Hungary-advert.html and http://indico.cern.ch/event/532397/.

  10. Deuteron and neutron induced activation in the Eveda accelerator materials: implications for the accelerator maintenance

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, M.; Sanz, J.; Garcia, N.; Cabellos, O. [Madrid Univ. Politecnica, C/ Jose Gutierrez Abascal, lnstituto de Fusion Nuclear (Spain); Sauvan, R. [Universidad Nacional de Educacion a Distancia (UNED), Madrid (Spain); Moreno, C.; Sedano, L.A. [CIEMAT-Centro de Investigaciones Energeticas Medioambientales y Tecnologicas, Association Euratom-CIEMAT, Madrid (Spain)

    2007-07-01

    Full text of publication follows: The IFMIF (International Fusion Materials Irradiation Facility) is an accelerator-based DLi neutron source designed to test fusion reactor candidate materials for high fluence neutrons. Before deciding IFMIF construction, an engineering design and associated experimental data acquisition, defined as EVEDA, has been proposed. Along the EVEDA accelerator, deuteron beam losses collide with the accelerator materials, producing activation and consequent radiations responsible of dose. Calculation of the dose rates in the EVEDA accelerator room is necessary in order to analyze the feasibility for manual maintenance. Dose rates due to the activation produced by the deuteron beam losses interaction with the accelerator materials, will be calculated with the ACAB activation code, using EAF2007 library for deuteron activation cross-sections. Also, dose rates from the activation induced by the neutron source produced by the interaction of deuteron beam losses with the accelerator materials and the deuterium implanted in the structural lattice, will be calculated with the SRIM2006, TMAP7, DROSG2000/NEUYIE, MCNPX and ACAB codes. All calculations will be done for the EVEDA accelerator with the room temperature DTL structure, which is based on copper cavities for the DTL. Some calculations will be done for the superconducting DTL structure, based on niobium cavities for the DTL working at cryogenic temperature. Final analysis will show the dominant mechanisms and major radionuclides contributing to the surface dose rates. (authors)

  11. Relativistic particle acceleration in developing Alfv\\'{e}n turbulence

    CERN Document Server

    Matsukiyo, S; 10.1088/0004-637X/692/2/1004

    2009-01-01

    A new particle acceleration process in a developing Alfv\\'{e}n turbulence in the course of successive parametric instabilities of a relativistic pair plasma is investigated by utilyzing one-dimensional electromagnetic full particle code. Coherent wave-particle interactions result in efficient particle acceleration leading to a power-law like energy distribution function. In the simulation high energy particles having large relativistic masses are preferentially accelerated as the turbulence spectrum evolves in time. Main acceleration mechanism is simultaneous relativistic resonance between a particle and two different waves. An analytical expression of maximum attainable energy in such wave-particle interactions is derived.

  12. Double layer -- a particle accelerator in the magnetosphere

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Xiangrong [Los Alamos National Laboratory

    2015-07-16

    Slides present the material under the following topics: Introduction (What is a double layer (DL)? Why is it important? Key unsolved problems); Theory -- time-independent solutions of 1D Vlasov--Poisson system; Particle-in-cell simulations (Current-driven DLs); and Electron acceleration by DL (Betatron acceleration). Key problems include the generation mechanism, stability, and electron acceleration. In summary, recent observations by Van Allen Probes show large number of DLs in the outer radiation belt, associated with enhanced flux of relativistic electrons. Simulations show that ion acoustic double layers can be generated by field-aligned currents. Thermal electrons can gain energy via betatron acceleration in a dipole magnetic field.

  13. 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

    2016-08-16

    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

  14. Intermittent sea-level acceleration

    Science.gov (United States)

    Olivieri, M.; Spada, G.

    2013-10-01

    Using instrumental observations from the Permanent Service for Mean Sea Level (PSMSL), we provide a new assessment of the global sea-level acceleration for the last ~ 2 centuries (1820-2010). Our results, obtained by a stack of tide gauge time series, confirm the existence of a global sea-level acceleration (GSLA) and, coherently with independent assessments so far, they point to a value close to 0.01 mm/yr2. However, differently from previous studies, we discuss how change points or abrupt inflections in individual sea-level time series have contributed to the GSLA. Our analysis, based on methods borrowed from econometrics, suggests the existence of two distinct driving mechanisms for the GSLA, both involving a minority of tide gauges globally. The first effectively implies a gradual increase in the rate of sea-level rise at individual tide gauges, while the second is manifest through a sequence of catastrophic variations of the sea-level trend. These occurred intermittently since the end of the 19th century and became more frequent during the last four decades.

  15. On Solar Wind Origin and Acceleration: Measurements from ACE

    Science.gov (United States)

    Stakhiv, Mark; Lepri, Susan T.; Landi, Enrico; Tracy, Patrick; Zurbuchen, Thomas H.

    2016-10-01

    The origin and acceleration of the solar wind are still debated. In this paper, we search for signatures of the source region and acceleration mechanism of the solar wind in the plasma properties measured in situ by the Advanced Composition Explorer spacecraft. Using the elemental abundances as a proxy for the source region and the differential velocity and ion temperature ratios as a proxy for the acceleration mechanism, we are able to identify signatures pointing toward possible source regions and acceleration mechanisms. We find that the fast solar wind in the ecliptic plane is the same as that observed from the polar regions and is consistent with wave acceleration and coronal-hole origin. We also find that the slow wind is composed of two components: one similar to the fast solar wind (with slower velocity) and the other likely originating from closed magnetic loops. Both components of the slow solar wind show signatures of wave acceleration. From these findings, we draw a scenario that envisions two types of wind, with different source regions and release mechanisms, but the same wave acceleration mechanism.

  16. Ion acceleration processes at reforming collisionless shocks

    CERN Document Server

    Lee, R E; Dendy, R O

    2004-01-01

    The identification of pre-acceleration mechanisms for cosmic ray ions in supernova remnant shocks is an important problem in astrophysics. Recent particle-in-cell (PIC) shock simulations have shown that inclusion of the full electron kinetics yields non-time-stationary solutions, in contrast to previous hybrid (kinetic ions, fluid electrons) simulations. Here, by running a PIC code at high phase space resolution, ion acceleration mechanisms associated with the time dependence of a supercritical collisionless perpendicular shock are examined. In particular the components of $\\int \\mathbf{F} \\cdot \\mathbf{v} dt$ are analysed along trajectories for ions that reach both high and low energies. Selection mechanisms for the ions that reach high energies are also examined. In contrast to quasi-stationary shock solutions, the suprathermal protons are selected from the background population on the basis of the time at which they arrive at the shock, and thus are generated in bursts.

  17. Ion acceleration in a scalable MEMS RF-structure for a compact linear accelerator

    CERN Document Server

    Persaud, A; Feinberg, E; Seidl, P A; Waldron, W L; Lal, A; Vinayakumar, K B; Ardanuc, S; Schenkel, T

    2016-01-01

    A new approach for a compact radio-frequency(rf) accelerator structure is presented. The idea is based on the Multiple Electrostatic Quadrupole Array Linear Accelerator (MEQALAC) structure that was first developed in the 1980s. The MEQALAC allowed scaling of rf-structure down to dimensions of centimeters while at the same time allowing for higher beam currents through parallel beamlets. Using micro-electro-mechanical systems (MEMS) for highly scalable fabrication, we reduce the critical dimension to the sub-millimeter regime, while massively scaling up the potential number of parallel beamlets. The technology is based on rf-acceleration components and electrostatic quadrupoles (ESQs) implemented in a silicon wafer based design where each beamlet passes through beam apertures in the wafer. The complete accelerator is then assembled by stacking these wafers. This approach allows fast and cheap batch fabrication of the components and flexibility in system design for different applications. For prototyping these ...

  18. Giga-electronvolt electrons due to a transition from laser wakefield acceleration to plasma wakefield acceleration

    International Nuclear Information System (INIS)

    We show through experiments that a transition from laser wakefield acceleration (LWFA) regime to a plasma wakefield acceleration (PWFA) regime can drive electrons up to energies close to the GeV level. Initially, the acceleration mechanism is dominated by the bubble created by the laser in the nonlinear regime of LWFA, leading to an injection of a large number of electrons. After propagation beyond the depletion length, leading to a depletion of the laser pulse, whose transverse ponderomotive force is not able to sustain the bubble anymore, the high energy dense bunch of electrons propagating inside bubble will drive its own wakefield by a PWFA regime. This wakefield will be able to trap and accelerate a population of electrons up to the GeV level during this second stage. Three dimensional particle-in-cell simulations support this analysis and confirm the scenario

  19. Giga-electronvolt electrons due to a transition from laser wakefield acceleration to plasma wakefield acceleration

    Science.gov (United States)

    Masson-Laborde, P. E.; Mo, M. Z.; Ali, A.; Fourmaux, S.; Lassonde, P.; Kieffer, J. C.; Rozmus, W.; Teychenné, D.; Fedosejevs, R.

    2014-12-01

    We show through experiments that a transition from laser wakefield acceleration (LWFA) regime to a plasma wakefield acceleration (PWFA) regime can drive electrons up to energies close to the GeV level. Initially, the acceleration mechanism is dominated by the bubble created by the laser in the nonlinear regime of LWFA, leading to an injection of a large number of electrons. After propagation beyond the depletion length, leading to a depletion of the laser pulse, whose transverse ponderomotive force is not able to sustain the bubble anymore, the high energy dense bunch of electrons propagating inside bubble will drive its own wakefield by a PWFA regime. This wakefield will be able to trap and accelerate a population of electrons up to the GeV level during this second stage. Three dimensional particle-in-cell simulations support this analysis and confirm the scenario.

  20. AESS: Accelerated Exact Stochastic Simulation

    Science.gov (United States)

    Jenkins, David D.; Peterson, Gregory D.

    2011-12-01

    The Stochastic Simulation Algorithm (SSA) developed by Gillespie provides a powerful mechanism for exploring the behavior of chemical systems with small species populations or with important noise contributions. Gene circuit simulations for systems biology commonly employ the SSA method, as do ecological applications. This algorithm tends to be computationally expensive, so researchers seek an efficient implementation of SSA. In this program package, the Accelerated Exact Stochastic Simulation Algorithm (AESS) contains optimized implementations of Gillespie's SSA that improve the performance of individual simulation runs or ensembles of simulations used for sweeping parameters or to provide statistically significant results. Program summaryProgram title: AESS Catalogue identifier: AEJW_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEJW_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: University of Tennessee copyright agreement No. of lines in distributed program, including test data, etc.: 10 861 No. of bytes in distributed program, including test data, etc.: 394 631 Distribution format: tar.gz Programming language: C for processors, CUDA for NVIDIA GPUs Computer: Developed and tested on various x86 computers and NVIDIA C1060 Tesla and GTX 480 Fermi GPUs. The system targets x86 workstations, optionally with multicore processors or NVIDIA GPUs as accelerators. Operating system: Tested under Ubuntu Linux OS and CentOS 5.5 Linux OS Classification: 3, 16.12 Nature of problem: Simulation of chemical systems, particularly with low species populations, can be accurately performed using Gillespie's method of stochastic simulation. Numerous variations on the original stochastic simulation algorithm have been developed, including approaches that produce results with statistics that exactly match the chemical master equation (CME) as well as other approaches that approximate the CME. Solution

  1. A new electrostatic accelerator: the vivitron

    International Nuclear Information System (INIS)

    The 35 MV electrostatic accelerator described in the present document operates according to Van de Graaff tandem type accelerator principles. This new accelerator has appreciable advantages over the classical machines built up to today: 1) reduced radial dimensions, and in consequence, a lower overall cast for identical or even lower limiting electric field values; 2) a significantly reduced stored electrical energy distributed in a homogeneous and better controlled way over the interelectrode space; 3) the use of discrete electrodes rather than classical intermediate screens enabling the advantages of direct electrical vision between the vessel and the high-tension electrode (voltage measurements and regulation by the Corona effect) to be retained. The reduced surface area of these electrodes improving both their characteristics when a voltage is applied and the mechanical behavior of the system; 4) a ''light'' internal structure enabling a horizontal machine to be envisaged

  2. Selective Acceleration in Impulsive Solar Flares

    Institute of Scientific and Technical Information of China (English)

    王德焴

    2001-01-01

    A plasma acceleration mechanism is proposed to explain the dramatic enhancement in the ratio of 3 He/4He, (enhancement factor 102 - 103) observed in solar 3He-rich flares. Considering that coronal plasma is mainly composed of hydrogen and helium ions, the hydrogen ion-helium ion hybrid waves and quasi-perpendicular waves can be excited by energetic electron beam during the impulsive solarflares. The frequencies of these waves are close to the 3He++ ion gyrofrequency, but far from the 4He++ ion gyrofrequency. Most of these waves are selectively absorbed by 3He ions. These preheated 3He ions can be successively stochastic accelerated by Alfvén turbulence, when their velocities are larger than the local Alfvén velocity. It makes the ratio of 3He/4He dramatically enhanced and the acceleration energy spectrum of 3He ions forms a power-law distribution during the impulsive solar flares.

  3. Protection of Accelerator Hardware: RF systems

    CERN Document Server

    Kim, S-H

    2016-01-01

    The radio-frequency (RF) system is the key element that generates electric fields for beam acceleration. To keep the system reliable, a highly sophisticated protection scheme is required, which also should be designed to ensure a good balance between beam availability and machine safety. Since RF systems are complex, incorporating high-voltage and high-power equipment, a good portion of machine downtime typically comes from RF systems. Equipment and component damage in RF systems results in long and expensive repairs. Protection of RF system hardware is one of the oldest machine protection concepts, dealing with the protection of individual high-power RF equipment from breakdowns. As beam power increases in modern accelerators, the protection of accelerating structures from beam-induced faults also becomes a critical aspect of protection schemes. In this article, an overview of the RF system is given, and selected topics of failure mechanisms and examples of protection requirements are introduced.

  4. A Statistical Perspective on Highly Accelerated Testing.

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Edward V.

    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

  5. Born Reciprocity and Cosmic Accelerations

    CERN Document Server

    Bolognesi, S

    2015-01-01

    The trans-Planckian theory is a model that realizes concretely the Born reciprocity idea, which is the postulate of absolute equivalence between coordinate $x$ and momenta $p$. This model is intrinsically global, and thus it is naturally implemented in a cosmological setting. Cosmology and Born reciprocity are made for each other. Inflation provides the essential mechanism to suppress the terms coming from the dual part of the action. The trans-Planckian theory, on the other hand, provides an explanation for the accelerated periods of the universe scale factor, both the inflationary period and the present period dominated by dark energy. All of this is possible just considering a simple model that contains gravity, one gauge field plus one matter field (to be identified with dark matter) together with the reciprocity principle.

  6. Accelerating the life of transistors

    Institute of Scientific and Technical Information of China (English)

    Qi Haochun; Lü Changzhi; Zhang Xiaoling; Xie Xuesong

    2013-01-01

    Choosing small and medium power switching transistors of the NPN type in a 3DK set as the study object,the test of accelerating life is conducted in constant temperature and humidity,and then the data are statistically analyzed with software developed by ourselves.According to degradations of such sensitive parameters as the reverse leakage current of transistors,the lifetime order of transistors is about more than 104 at 100 ℃ and 100% relative humidity (RH) conditions.By corrosion fracture of transistor outer leads and other failure modes,with the failure truncated testing,the average lifetime rank of transistors in different distributions is extrapolated about 103.Failure mechanism analyses of degradation of electrical parameters,outer lead fracture and other reasons that affect transistor lifetime are conducted.The findings show that the impact of external stress of outer leads on transistor reliability is more serious than that of parameter degradation.

  7. Accelerator system for neutron radiography

    International Nuclear Information System (INIS)

    The field of x-ray radiography is well established for doing non-destructive evaluation of a vast array of components, assemblies, and objects. While x-rays excel in many radiography applications, their effectiveness diminishes rapidly if the objects of interest are surrounded by thick, high-density materials that strongly attenuate photons. Due to the differences in interaction mechanisms, neutron radiography is highly effective in imaging details inside such objects. To obtain a high intensity neutron source suitable for neutron imaging a 9-MeV linear accelerator is being evaluated for putting a deuteron beam into a high-pressure deuterium gas cell. As a windowless aperture is needed to transport the beam into the gas cell, a low-emittance is needed to minimize losses along the high-energy beam transport (HEBT) and the end station. A description of the HEBT, the transport optics into the gas cell, and the requirements for the linac will be presented

  8. Accelerating the life of transistors

    Science.gov (United States)

    Haochun, Qi; Changzhi, Lü; Xiaoling, Zhang; Xuesong, Xie

    2013-06-01

    Choosing small and medium power switching transistors of the NPN type in a 3DK set as the study object, the test of accelerating life is conducted in constant temperature and humidity, and then the data are statistically analyzed with software developed by ourselves. According to degradations of such sensitive parameters as the reverse leakage current of transistors, the lifetime order of transistors is about more than 104 at 100 °C and 100% relative humidity (RH) conditions. By corrosion fracture of transistor outer leads and other failure modes, with the failure truncated testing, the average lifetime rank of transistors in different distributions is extrapolated about 103. Failure mechanism analyses of degradation of electrical parameters, outer lead fracture and other reasons that affect transistor lifetime are conducted. The findings show that the impact of external stress of outer leads on transistor reliability is more serious than that of parameter degradation.

  9. Embryonic development during chronic acceleration

    Science.gov (United States)

    Smith, A. H.; Abbott, U. K.

    1982-01-01

    Experiments carried out on chicken eggs indicate that the embryo is affected during very early development, especially over the first four days, and during hatching. In the first four days, the brain develops as well as the anlage for all other organs. In addition, the heart commences to function and the extraembryonic membranes that compartmentalize the egg contents form. The latter require an appreciable extension and folding of tissue which may be disrupted by the mechanical load. Observations of embryonic abnormalities that occur during chronic acceleration suggest an inhibition of development of the axial skeleton, which is rarely seen otherwise, a general retardation of embryonic growth, and circulatory problems. The final stages of development (after 18 days) involve the uptake of fluids, the transition to aerial respiration, and the reorientation of the embryo into a normal hatching position. At 4 G mortality is very high during this period, with a majority of embryos failing to reorient into the normal hatching position.

  10. Accelerated Characterization of Polymer Properties

    Energy Technology Data Exchange (ETDEWEB)

    R. Wroczynski; l. Brewer; D. Buckley; M. Burrell; R. Potyrailo

    2003-07-30

    This report describes the efforts to develop a suite of microanalysis techniques that can rapidly measure a variety of polymer properties of industrial importance, including thermal, photo-oxidative, and color stability; as well as ductility, viscosity, and mechanical and antistatic properties. Additional goals of the project were to direct the development of these techniques toward simultaneous measurements of multiple polymer samples of small size in real time using non-destructive and/or parallel or rapid sequential measurements, to develop microcompounding techniques for preparing polymers with additives, and to demonstrate that samples prepared in the microcompounder could be analyzed directly or used in rapid off-line measurements. These enabling technologies are the crucial precursors to the development of high-throughput screening (HTS) methodologies for the polymer additives industry whereby the rate of development of new additives and polymer formulations can be greatly accelerated.

  11. Database automation of accelerator operation

    International Nuclear Information System (INIS)

    Database management techniques are applied to automating the setup of operating parameters of a heavy-ion accelerator used in nuclear physics experiments. Data files consist of ion-beam attributes, the interconnection assignments of the numerous power supplies and magnetic elements that steer the ions' path through the system, the data values that represent the electrical currents supplied by the power supplies, as well as the positions of motors and status of mechanical actuators. The database is relational and permits searching on ranges of any subset of the ion-beam attributes. A file selected from the database is used by the control software to replicate the ion beam conditions by adjusting the physical elements in a continuous manner

  12. Theoretical Aspects of Cosmic Acceleration

    CERN Document Server

    Trodden, Mark

    2016-01-01

    Efforts to understand and map the possible explanations for the late time acceleration of the universe have led to a broad range of suggestions, ranging from the cosmological constant and straightforward dark energy, to exotically coupled models, to infrared modifications of General Relativity. If we are to uncover which, if any, of these approaches might provide a serious answer to the problem, it is crucial to understand the constraints that theoretical consistency places on the models, and on the regimes in which they make predictions. In this talk, delivered as an invited plenary lecture at the Dark Side of the Universe conference in Kyoto, Japan, I briefly describe some modern attempts to carry out this program and some of the more interesting ideas that have emerged. As an example, I use the Galileon model, discussing how the Vainshtein mechanism occurs, and how a number of these theoretical problems arise around such backgrounds.

  13. Particle Acceleration in an Evolving Network of Unstable Current Sheets

    CERN Document Server

    Vlahos, L; Lepreti, F

    2004-01-01

    We study the acceleration of electrons and protons interacting with localized, multiple, small-scale dissipation regions inside an evolving, turbulent active region. The dissipation regions are Unstable Current Sheets (UCS), and in their ensemble they form a complex, fractal, evolving network of acceleration centers. Acceleration and energy dissipation are thus assumed to be fragmented. A large-scale magnetic topology provides the connectivity between the UCS and determines in this way the degree of possible multiple acceleration. The particles travel along the magnetic field freely without loosing or gaining energy, till they reach a UCS. In a UCS, a variety of acceleration mechanisms are active, with the end-result that the particles depart with a new momentum. The stochastic acceleration process is represented in the form of Continuous Time Random Walk (CTRW), which allows to estimate the evolution of the energy distribution of the particles. It is found that under certain conditions electrons are heated a...

  14. Acceleration Workspace of Cooperating Multi-Finger Robot Systems

    Institute of Scientific and Technical Information of China (English)

    Hyungwon Shim; Jihong Lee

    2008-01-01

    We present a mathematical method for acceleration workspace analysis of cooperating multi-finger robot systems using a model of point-contact with friction. A new unified formulation from dynamic equations of cooperating multi-finger robots is derived considering the force and acceleration relationships between the fingers and the object to be handled. From the dynamic equation, maximum translational and rotational acceleration bounds of an object are calculated under given constraints of contact conditions, configurations of fingers, and bounds on the torques of joint actuators for each finger. Here, the rotational acceleration bounds can be applied as an important manipulability index when the multi-finger robot grasps an object. To verify the proposed method, we used a set of case studies with a simple multi-finger mechanism system. The achievable acceleration boundary in task space can be obtained successfully with the proposed method and the acceleration boundary depends on the configurations of fingers.

  15. Accelerator mass spectrometry programme at Mumbai pelletron accelerator facility

    International Nuclear Information System (INIS)

    The Accelerator Mass Spectrometry (AMS) programme and the related developments based on the Mumbai Pelletron accelerator are described. The initial results of the measurement of the ratio, 36Cl / Cl in water samples are presented. (author)

  16. Accelerated stability testing of organic photovoltaics using concentrated sunlight

    DEFF Research Database (Denmark)

    Katz, Eugene A.; Manor, Assaf; Mescheloff, Asaf;

    2012-01-01

    We suggest to use concentrated sunlight for accelerated studies of light-induced mechanisms in the degradation of organic photovoltaics (OPV) based on the polymer (P3HT)/fullerene (PCBM) bulk heterojunctions. Two particular cases of the degradation are reported.......We suggest to use concentrated sunlight for accelerated studies of light-induced mechanisms in the degradation of organic photovoltaics (OPV) based on the polymer (P3HT)/fullerene (PCBM) bulk heterojunctions. Two particular cases of the degradation are reported....

  17. 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)

  18. Accelerator research studies

    International Nuclear Information System (INIS)

    The Accelerator Research Studies program at the University of Maryland, sponsored by the Department of Energy under contract number AC05-85ER40216-8, is currently in the third year of its three-year funding cycle. This Renewal Proposal requests DOE support for the next three-year period from June 1, 1991 to May 31, 1994. It documents the progress made during the past year and outlines the proposed research program for the next three years. The program consisted of the following three tasks: Task A, ''Study of Transport and Longitudinal Compression of Intense, High-Brightness Beams,'' Task B, ''Study of Collective Ion Acceleration by Intense Electron Beams and Pseudospark Produced High Brightness Electron Beams,'' Task C, ''Study of a Gyroklystron High-Power Microwave Source for Linear Colliders.'' These tasks will be discussed in this paper

  19. Accelerator research studies

    International Nuclear Information System (INIS)

    The Accelerator Research Studies program at the University of Maryland, sponsored by the Department of Energy under grant number DE-FG05-91ER40642, is currently in the first year of a three-year funding cycle. The program consists of the following three tasks: TASK A, Study of Transport and Longitudinal Compression of Intense, High-Brightness Beams, TASK B, Study of Collective Ion Acceleration by Intense Electron Beams and Pseudospark Produced High Brightness Electron Beams; TASK C, Study of a Gyroklystron High-power Microwave Source for Linear Colliders. In this report we document the progress that has been made during the past year for each of the three tasks

  20. Accelerated Parallel Texture Optimization

    Institute of Scientific and Technical Information of China (English)

    Hao-Da Huang; Xin Tong; Wen-Cheng Wang

    2007-01-01

    Texture optimization is a texture synthesis method that can efficiently reproduce various features of exemplar textures. However, its slow synthesis speed limits its usage in many interactive or real time applications. In this paper, we propose a parallel texture optimization algorithm to run on GPUs. In our algorithm, k-coherence search and principle component analysis (PCA) are used for hardware acceleration, and two acceleration techniques are further developed to speed up our GPU-based texture optimization. With a reasonable precomputation cost, the online synthesis speed of our algorithm is 4000+ times faster than that of the original texture optimization algorithm and thus our algorithm is capable of interactive applications. The advantages of the new scheme are demonstrated by applying it to interactive editing of flow-guided synthesis.

  1. Hardware Accelerated Simulated Radiography

    Energy Technology Data Exchange (ETDEWEB)

    Laney, D; Callahan, S; Max, N; Silva, C; Langer, S; Frank, R

    2005-04-12

    We present the application of hardware accelerated volume rendering algorithms to the simulation of radiographs as an aid to scientists designing experiments, validating simulation codes, and understanding experimental data. The techniques presented take advantage of 32 bit floating point texture capabilities to obtain validated solutions to the radiative transport equation for X-rays. An unsorted hexahedron projection algorithm is presented for curvilinear hexahedra that produces simulated radiographs in the absorption-only regime. A sorted tetrahedral projection algorithm is presented that simulates radiographs of emissive materials. We apply the tetrahedral projection algorithm to the simulation of experimental diagnostics for inertial confinement fusion experiments on a laser at the University of Rochester. We show that the hardware accelerated solution is faster than the current technique used by scientists.

  2. Accelerating QDP++ using GPUs

    CERN Document Server

    Winter, Frank

    2011-01-01

    Graphic Processing Units (GPUs) are getting increasingly important as target architectures in scientific High Performance Computing (HPC). NVIDIA established CUDA as a parallel computing architecture controlling and making use of the compute power of GPUs. CUDA provides sufficient support for C++ language elements to enable the Expression Template (ET) technique in the device memory domain. QDP++ is a C++ vector class library suited for quantum field theory which provides vector data types and expressions and forms the basis of the lattice QCD software suite Chroma. In this work accelerating QDP++ expression evaluation to a GPU was successfully implemented leveraging the ET technique and using Just-In-Time (JIT) compilation. The Portable Expression Template Engine (PETE) and the C API for CUDA kernel arguments were used to build the bridge between host and device memory domains. This provides the possibility to accelerate Chroma routines to a GPU which are typically not subject to special optimisation. As an ...

  3. Accelerator research studies

    International Nuclear Information System (INIS)

    The Accelerator Research Studies program at the University of Maryland, sponsored by the Department of Energy under grant number DE-FG05-91ER40642, is currently in the second year of a three-year funding cycle. The program consists of the following three tasks: TASK A, ''Study of Transport and Longitudinal Compression of Intense, High-Brightness Beams,'' (P.I., M. Reiser); TASK B, ''Study of Collective Ion Acceleration by Intense Electron Beams and Pseudospark Produced High Brightness Electron Beams,'' (Co-P.I.'s, W.W. Destler, M. Reiser, M.J. Rhee, and C.D. Striffler); TASK C, ''Study of a Gyroklystron High-Power Microwave Source for Linear Colliders,'' (Co-P.I.'s, V.L. Granatstein, W. Lawson, M. Reiser, and C.D. Striffler). In this report we document the progress that has been made during the past year for each of the three tasks

  4. accelerating cavity from LEP

    CERN Multimedia

    This is an accelerating cavity from LEP, with a layer of niobium on the inside. Operating at 4.2 degrees above absolute zero, the niobium is superconducting and carries an accelerating field of 6 million volts per metre with negligible losses. Each cavity has a surface of 6 m2. The niobium layer is only 1.2 microns thick, ten times thinner than a hair. Such a large area had never been coated to such a high accuracy. A speck of dust could ruin the performance of the whole cavity so the work had to be done in an extremely clean environment. These challenging requirements pushed European industry to new achievements. 256 of these cavities are now used in LEP to double the energy of the particle beams.

  5. Accelerator research studies

    International Nuclear Information System (INIS)

    This progress report for the Accelerator Research Studies program at the University of Maryland covers the second year (June 1, 1989 to May 31, 1990) of the current three-year contract period from June 1, 1988 to May 31, 1991, funded by the Department of Energy under Contract No. AC05-85ER40216. The research program is divided into three separate tasks, as follows: the study of Transport and Longitudinal Compression of Intense, High-Brightness Beams; the study of Collective Ion Acceleration by Intense Electron Beams and Pulse-Powered Plasma Focus; the study of Microwave Sources and Parameter Scaling for High-Frequency Linacs. This report consists of three sections in which the progress for each task is documented separately. An introduction and synopsis is presented at the beginning of the progress report for each task

  6. NEW ACCELERATION METHODS

    Energy Technology Data Exchange (ETDEWEB)

    Sessler, A.M.

    1984-07-01

    But a glance at the Livingston chart, Fig. 1, of accelerator particle energy as a function of time shows that the energy has steadily, exponentially, increased. Equally significant is the fact that this increase is the envelope of diverse technologies. If one is to stay on, or even near, the Livingston curve in future years then new acceleration techniques need to be developed. What are the new acceleration methods? In these two lectures I would like to sketch some of these new ideas. I am well aware that they will probably not result in high energy accelerators within this or the next decade, but conversely, it is likely that these ideas will form the basis for the accelerators of the next century. Anyway, the ideas are stimulating and suffice to show that accelerator physicists are not just 'engineers', but genuine scientists deserving to be welcomed into the company of high energy physicists. I believe that outsiders will find this field surprisingly fertile and, certainly fun. To put it more personally, I very much enjoy working in this field and lecturing on it. There are a number of review articles which should be consulted for references to the original literature. In addition there are three books on the subject. Given this material, I feel free to not completely reference the material in the remainder of this article; consultation of the review articles and books will be adequate as an introduction to the literature for references abound (hundreds are given). At last, by way of introduction, I should like to quote from the end of Ref. 2 for I think the remarks made there are most germane. Remember that the talk was addressed to accelerator physicists: 'Finally, it is often said, I think by physicists who are not well-informed, that accelerator builders have used up their capital and now are bereft of ideas, and as a result, high energy physics will eventually--rather soon, in fact--come to a halt. After all, one can't build too many

  7. RFQ accelerator development

    International Nuclear Information System (INIS)

    Radio frequency quadrupole (RFQ) accelerators have established themselves as highly efficient and potential tools for delivering intense beams of the order of 100 mA or more. They are being employed as injectors to high energy machines used for basic sciences, spallation neutron sources, fusion devices and accelerator breeders. They have also made their mark as neutron generators, ion implanters, x-ray generators, etc. Realising the importance of this programme, Bhabha Atomic Research Centre initiated a totally indigenous effort to develop RFQs for the light as well as heavy ion beams. A low power RFQ for the proton and deuteron beams is already in the final phase of commissioning. (author). 30 refs., 14 figs., 2 tabs

  8. Particle accelerator physics

    CERN Document Server

    Wiedemann, Helmut

    2015-01-01

    This book by Helmut Wiedemann is a well-established, classic text, providing an in-depth and comprehensive introduction to the field of high-energy particle acceleration and beam dynamics. The present 4th edition has been significantly revised, updated and expanded. The newly conceived Part I is an elementary introduction to the subject matter for undergraduate students. Part II gathers the basic tools in preparation of a more advanced treatment, summarizing the essentials of electrostatics and electrodynamics as well as of particle dynamics in electromagnetic fields. Part III is an extensive primer in beam dynamics, followed, in Part IV, by an introduction and description of the main beam parameters and including a new chapter on beam emittance and lattice design. Part V is devoted to the treatment of perturbations in beam dynamics. Part VI then discusses the details of charged particle acceleration. Parts VII and VIII introduce the more advanced topics of coupled beam dynamics and describe very intense bea...

  9. Accelerators for Cancer Therapy

    Science.gov (United States)

    Lennox, Arlene J.

    2000-05-30

    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.

  10. Particle acceleration by pulsars

    International Nuclear Information System (INIS)

    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

  11. GPU accelerated face detection

    OpenAIRE

    Mäkelä, J.

    2013-01-01

    Graphics processing units have massive parallel processing capabilities, and there is a growing interest in utilizing them for generic computing. One area of interest is computationally heavy computer vision algorithms, such as face detection and recognition. Face detection is used in a variety of applications, for example the autofocus on cameras, face and emotion recognition, and access control. In this thesis, the face detection algorithm was accelerated with GPU using OpenCL. The goal was...

  12. Accelerator Experiments for Astrophysics

    OpenAIRE

    Ng, Johnny S. T.

    2003-01-01

    Many recent discoveries in astrophysics involve phenomena that are highly complex. Carefully designed experiments, together with sophisticated computer simulations, are required to gain insights into the underlying physics. We show that particle accelerators are unique tools in this area of research, by providing precision calibration data and by creating extreme experimental conditions relevant for astrophysics. In this paper we discuss laboratory experiments that can be carried out at the S...

  13. Compact pulsed accelerator

    International Nuclear Information System (INIS)

    The formation of fast pulses from a current charged transmission line and opening switch is described. By employing a plasma focus as an opening switch and diode in the prototype device, a proton beam of peak energy 250 keV is produced. The time integrated energy spectrum of the beam is constructed from a Thomson spectrograph. Applications of this device as an inexpensive and portable charged particle accelerator are discussed. 7 refs., 5 figs., 1 tab

  14. Laser plasma accelerators

    OpenAIRE

    Malka, V.

    2012-01-01

    Research activities on laser plasma accelerators are paved by many significant breakthroughs. This review article provides an opportunity to show the incredible evolution of this field of research which has, in record time, allowed physicists to produce high quality electron beams at the GeV level using compact laser systems. I will show the scientific path that led us to explore different injection schemes and to produce stable, high peak current and high quality electron beams with control ...

  15. LEP copper accelerating cavities

    CERN Multimedia

    Laurent Guiraud

    1999-01-01

    These copper cavities were used to generate the radio frequency electric field that was used to accelerate electrons and positrons around the 27-km Large Electron-Positron (LEP) collider at CERN, which ran from 1989 to 2000. The copper cavities were gradually replaced from 1996 with new superconducting cavities allowing the collision energy to rise from 90 GeV to 200 GeV by mid-1999.

  16. Accelerated plate tectonics.

    Science.gov (United States)

    Anderson, D L

    1975-03-21

    The concept of a stressed elastic lithospheric plate riding on a viscous asthenosphere is used to calculate the recurrence interval of great earthquakes at convergent plate boundaries, the separation of decoupling and lithospheric earthquakes, and the migration pattern of large earthquakes along an arc. It is proposed that plate motions accelerate after great decoupling earthquakes and that most of the observed plate motions occur during short periods of time, separated by periods of relative quiescence.

  17. Future Accelerator Magnet Needs

    CERN Document Server

    Devred, Arnaud; Yamamoto, A

    2005-01-01

    Superconducting magnet technology is continually evolving in order to meet the demanding needs of new accelerators and to provide necessary upgrades for existing machines. A variety of designs are now under development, including high fields and gradients, rapid cycling and novel coil configurations. This paper presents a summary of R&D programs in the EU, Japan and the USA. A performance comparison between NbTi and Nb3Sn along with fabrication and cost issues are also discussed.

  18. Shock accelerated vortex ring

    CERN Document Server

    Haehn, N; Oakley, J; Anderson, M; Rothamer, D; Bonazza, R

    2009-01-01

    The interaction of a shock wave with a spherical density inhomogeneity leads to the development of a vortex ring through the impulsive deposition of baroclinic vorticity. The present fluid dynamics videos display this phenomenon and were experimentally investigated at the Wisconsin Shock Tube Laboratory's (WiSTL) 9.2 m, downward firing shock tube. The tube has a square internal cross-section (0.25 m x 0.25 m) with multiple fused silica windows for optical access. The spherical soap bubble is generated by means of a pneumatically retracted injector and released into free-fall 200 ms prior to initial shock acceleration. The downward moving, M = 2.07 shock wave impulsively accelerates the bubble and reflects off the tube end wall. The reflected shock wave re-accelerates the bubble (reshock), which has now developed into a vortex ring, depositing additional vorticity. In the absence of any flow disturbances, the flow behind the reflected shock wave is stationary. As a result, any observed motion of the vortex rin...

  19. Accelerated Profile HMM Searches.

    Directory of Open Access Journals (Sweden)

    Sean R Eddy

    2011-10-01

    Full Text Available Profile hidden Markov models (profile HMMs and probabilistic inference methods have made important contributions to the theory of sequence database homology search. However, practical use of profile HMM methods has been hindered by the computational expense of existing software implementations. Here I describe an acceleration heuristic for profile HMMs, the "multiple segment Viterbi" (MSV algorithm. The MSV algorithm computes an optimal sum of multiple ungapped local alignment segments using a striped vector-parallel approach previously described for fast Smith/Waterman alignment. MSV scores follow the same statistical distribution as gapped optimal local alignment scores, allowing rapid evaluation of significance of an MSV score and thus facilitating its use as a heuristic filter. I also describe a 20-fold acceleration of the standard profile HMM Forward/Backward algorithms using a method I call "sparse rescaling". These methods are assembled in a pipeline in which high-scoring MSV hits are passed on for reanalysis with the full HMM Forward/Backward algorithm. This accelerated pipeline is implemented in the freely available HMMER3 software package. Performance benchmarks show that the use of the heuristic MSV filter sacrifices negligible sensitivity compared to unaccelerated profile HMM searches. HMMER3 is substantially more sensitive and 100- to 1000-fold faster than HMMER2. HMMER3 is now about as fast as BLAST for protein searches.

  20. Optimizing accelerator technology

    CERN Multimedia

    Katarina Anthony

    2012-01-01

    A new EU-funded research and training network, oPAC, is bringing together 22 universities, research centres and industry partners to optimize particle accelerator technology. CERN is one of the network’s main partners and will host 5 early-stage researchers in the BE department.   A diamond detector that will be used for novel beam diagnostics applications in the oPAC project based at CIVIDEC. (Image courtesy of CIVIDEC.) As one of the largest Marie Curie Initial Training Networks ever funded by the EU – to the tune of €6 million – oPAC extends well beyond the particle physics community. “Accelerator physics has become integral to research in almost every scientific discipline – be it biology and life science, medicine, geology and material science, or fundamental physics,” explains Carsten P. Welsch, oPAC co-ordinator based at the University of Liverpool. “By optimizing the operation of accelerators, all of these...

  1. Accelerated GLAS exposure station

    International Nuclear Information System (INIS)

    The Geoscience Laser Altimeter System (GLAS) is being developed by NASA/GSFC to measure the dynamics of the ice sheet mass balance, land, and cloud and atmospheric properties. An instrument altimetric resolution of 10 cm per shot is required. The laser transmitter will be a diode pumped, Q-switched, Nd:YAG laser producing 1064 nm, 100 mJ, 4 ns pulses at 40 Hz repetition rate in a TEM∞ mode. A minimum lifetime goal of 2 billion shots is required per laser transmitter. The performance of the GLAS laser can be limited by physical damage to the optical components caused by the interaction of intense laser energy with the optical coatings and substrates. Very little data exists describing the effects of long duration laser exposure, of 4 ns pulses, on an optical component. An Accelerated GLAS Exposure Station (AGES) is being developed which will autonomously operate and monitor the GLAS laser at an accelerated rate of 500 Hz. The effects of a large number of laser shots will be recorded. Parameters to be monitored include: laser power, pulsewidth, beam size, laser diode drive current and power, Q-switch drive voltage, temperature, and humidity. For comparison, one set of AGES-sister optical components will be used in the non-accelerated GLAS laser and another will be evaluated by a commercial optical damage test facility

  2. Linac transport and acceleration

    International Nuclear Information System (INIS)

    The acceleration of intense bunches maintaining high brightness is limited both by single-particle effects, e.g., misalignments, injection errors, and rf-steering, and collective phenomena, where the effects of the longitudinal and transverse wakefield on particles within a single bunch are the most severe. The working group has considered both problems and potentials of linac acceleration from ∼50 MeV to 1 GeV for free electron laser (FEL) applications, as well as from a few Gev to 1 TeV for linear colliders. The outlook for free electron lasers is bright: no fundamental problems seem to arise in the acceleration of peak currents in excess of 100 A with small emittance and low momentum spread. The situation of linear colliders is more complex and more difficult. Two examples, one operating at 11.4 GHz, the other at 30 GHz, are used to illustrate some of the difficulties and the exceedingly tight tolerances required. Both examples are based on round beams, and thus neither benefit from the advantages of flat beams nor address the increased care required in transporting beams of very small emittance in one plane. The working group acknowledges, but did not explore, promising concepts for colliders based on RF superconductivity

  3. Acceleration during magnetic reconnection

    Energy Technology Data Exchange (ETDEWEB)

    Beresnyak, Andrey [Los Alamos National Laboratory; Li, Hui [Los Alamos National Laboratory

    2015-07-16

    The presentation begins with colorful depictions of solar x-ray flares and references to pulsar phenomena. Plasma reconnection is complex, could be x-point dominated or turbulent, field lines could break due to either resistivity or non-ideal effects, such as electron pressure anisotropy. Electron acceleration is sometimes observed, and sometimes not. One way to study this complex problem is to have many examples of the process (reconnection) and compare them; the other way is to simplify and come to something robust. Ideal MHD (E=0) turbulence driven by magnetic energy is assumed, and the first-order acceleration is sought. It is found that dissipation in big (length >100 ion skin depths) current sheets is universal and independent on microscopic resistivity and the mean imposed field; particles are regularly accelerated while experiencing curvature drift in flows driven by magnetic tension. One example of such flow is spontaneous reconnection. This explains hot electrons with a power-law tail in solar flares, as well as ultrashort time variability in some astrophysical sources.

  4. Laser driven particle acceleration

    International Nuclear Information System (INIS)

    This dissertation summarizes the last ten years of research at the Laboratory of Applied Optics on laser-plasma based electron acceleration. The main result consists of the development and study of a relativistic electron source with unique properties: high energy (100-300 MeV) in short distances (few millimeters), mono-energetic, ultra-short (few fs), stable and tunable. The manuscript describes the steps that led to understanding the physics, and then mastering it in order to produce this new electron source. Non linear propagation of the laser pulse in the plasma is first presented, with phenomena such as non linear wakefield excitation, relativistic and ponderomotive self-focusing in the short pulse regime, self-compression. Acceleration and injection of electrons are then reviewed from a theoretical perspective. Experimental demonstrations of self-injection in the bubble regime and then colliding pulse injection are then presented. These experiments were among the first to produce monoenergetic, high quality, stable and tunable electron beams from a laser-plasma accelerator. The last two chapters are dedicated to the characterization of the electron beam using transition radiation and to its applications to gamma radiography and radiotherapy. Finally, the perspectives of this research are presented in the conclusion. Scaling laws are used to determine the parameters that the electron beams will reach using peta-watt laser systems currently under construction. (author)

  5. Berkeley Proton Linear Accelerator

    Science.gov (United States)

    Alvarez, L. W.; Bradner, H.; Franck, J.; Gordon, H.; Gow, J. D.; Marshall, L. C.; Oppenheimer, F. F.; Panofsky, W. K. H.; Richman, C.; Woodyard, J. R.

    1953-10-13

    A linear accelerator, which increases the energy of protons from a 4 Mev Van de Graaff injector, to a final energy of 31.5 Mev, has been constructed. The accelerator consists of a cavity 40 feet long and 39 inches in diameter, excited at resonance in a longitudinal electric mode with a radio-frequency power of about 2.2 x 10{sup 6} watts peak at 202.5 mc. Acceleration is made possible by the introduction of 46 axial "drift tubes" into the cavity, which is designed such that the particles traverse the distance between the centers of successive tubes in one cycle of the r.f. power. The protons are longitudinally stable as in the synchrotron, and are stabilized transversely by the action of converging fields produced by focusing grids. The electrical cavity is constructed like an inverted airplane fuselage and is supported in a vacuum tank. Power is supplied by 9 high powered oscillators fed from a pulse generator of the artificial transmission line type.

  6. CESR Test Accelerator

    CERN Document Server

    Rubin, David L

    2013-01-01

    The Cornell Electron Storage Ring (CESR) was reconfigured in 2008 as a test accelerator to investigate the physics of ultra-low emittance damping rings. During the approximately 40 days/year available for dedicated operation as a test accelerator, specialized instrumentation is used to measure growth and mitigation of the electron cloud, emittance growth due to electron cloud, intra-beam scattering, and ions, and single and multi-bunch instabilities generated by collective effects. The flexibility of the CESR guide field optics and the integration of accelerator modeling codes with the control system have made possible an extraordinary range of experiments. Findings at CesrTA with respect to electron cloud effects, emittance tuning techniques, and beam instrumentation for measuring electron cloud, beam sizes, and beam positions are the basis for much of the design of the ILC damping rings as documented in the ILC-Technical Design Report. The program has allowed the Cornell group to cultivate the kind of talen...

  7. Exploring Particle Acceleration in Gamma-Ray Binaries

    Science.gov (United States)

    Bosch-Ramon, V.; Rieger, F. M.

    2012-08-01

    Binary systems can be powerful sources of non-thermal emission from radio to gamma rays. When the latter are detected, then these objects are known as gamma ray binaries. In this work, we explore, in the context of gamma ray binaries, different acceleration processes to estimate their efficiency: Fermi I, Fermi II, shear acceleration, the converter mechanism, and magnetic reconnection. We find that Fermi I acceleration in a mildly relativistic shock can provide, although marginally, the multi-10 TeV particles required to explain observations. Shear acceleration may be a complementary mechanism, giving particles the final boost to reach such a high energies. Fermi II acceleration may be too slow to account for the observed very high energy photons, but may be suitable to explain extended low-energy emission. The converter mechanism seems to require rather high Lorentz factors but cannot be discarded a priori. Standard relativistic shock acceleration requires a highly turbulent, weakly magnetized downstream medium; magnetic reconnection, by itself possibly insufficient to reach very high energies, could perhaps facilitate such a conditions. Further theoretical developments, and a better source characterization, are needed to pinpoint the dominant acceleration mechanism, which need not be one and the same in all sources.

  8. Laser-driven electron accelerators

    International Nuclear Information System (INIS)

    The following possibilities are discussed: inverse free electron laser (wiggler accelerator); inverse Cerenkov effect; plasma accelerator; dielectric tube; and grating linac. Of these, the grating acceleraton is considered the most attractive alternative

  9. Electron accelerators for environmental protection

    International Nuclear Information System (INIS)

    The primary objective of this publication is to provide information suitable for electron accelerators implementation in facilities applying radiation technology for environmental protection. It should be noticed that radiation processing has been successfully used in the fields of crosslinking polymer curing and medical products sterilization for more than 40 years. Practical application of radiation technology today extends on SO2 and NOx removal from the flue gas (one of major power intensive radiation processing), destruction and removal of organic chemicals from water, decreasing bacteria content in the irradiated sludge and waste water. On the other hand the increased awareness of environmental pollution hazards and more stringent waste regulations in many countries may open stronger support for environmentally oriented technologies. This publication provides an evaluation of electron accelerators capabilities in respect of environmental applications where technological and economical criteria are now well defined. In order to determine the potential of electron accelerators, the literature data were examined as well visits and meetings with various accelerator manufacturers were performed by the author. Experience of the author in accelerator facilities construction and exploitation including those which were used for environmental protection are significant part of this publication. The principle of accelerator action was described in Chapter 1. Early development, accelerator classification and fields of accelerators application were included to this chapter as well. Details of accelerator construction was described in Chapter 2 to illustrate physical capability of accelerators to perform the function of ionizing radiation source. Electron beam extraction devices, under beam equipment, electron beam parameters and measuring methods were characterized in this chapter as well. Present studies of accelerator technology was described in Chapter 3, where direct

  10. Accelerating in de Sitter spacetimes

    CERN Document Server

    Cotaescu, Ion I

    2014-01-01

    We propose a definition of uniform accelerated frames in de Sitter spacetimes exploiting the Nachtmann group theoretical method of introducing coordinates on these manifolds. Requiring the transformation between the static frame and the accelerated one to depend continuously on acceleration in order to recover the well-known Rindler approach in the flat limit, we obtain a result with a reasonable physical meaning.

  11. Numerical Investigation and Experimental Reproduction of Fermi Acceleration in Laboratory Scale

    Science.gov (United States)

    Zhou, M.; Zhai, C.

    2015-12-01

    Fermi acceleration is widely accepted as the mechanism to explain power law of cosmic ray spectrum. Now this mechanism has been developed to first order Fermi acceleration and second order Fermi acceleration. In first order Fermi acceleration, also known as diffusive shock acceleration, particles are confined around the shock through scattering and accelerated by repeatedly crossing shock front. In second order Fermi acceleration, particles gain energy through statistical collisions with interstellar clouds. In this proposed work, we plan to carefully study these two kinds of acceleration numerically and experimentally. We first consider a single relativistic particle and investigate how it gains energy in Fermi-Ulam model and shock wave acceleration model respectively. We investigate collective behavior of particles with different kinds of wall-oscillation functions and try to find an optimal one in terms of efficiency of acceleration. Then, we plan to go further and consider a group of particles statistically, during which we borrow the correct generalization of Maxwell's velocity distribution in special relativity and compare the results with those in cases where we simply use Maxwell-Boltzmann distribution. To this end, we try to provide a scheme to build an accelerator applying both laser technology and mirror effect in Laboratory to reproduce Fermi acceleration, which might be a promising source to obtain high energy particles and further study the mechanism of cosmic rays acceleration.

  12. Observation of particle acceleration in laboratory magnetosphere

    CERN Document Server

    Kawazura, Yohei; Nishiura, Masaki; Saitoh, Haruhiko; Yano, Yoshihisa; Nogami, Tomoaki; Sato, Naoki; Yamasaki, Miyuri; Kashyap, Ankur; Mushiake, Toshiki

    2015-01-01

    The self-organization of magnetospheric plasma is brought about by inward diffusion of magnetized particles. Not only creating a density gradient toward the center of a dipole magnetic field, the inward diffusion also accelerates particles and provides a planetary radiation belt with high energy particles. Here, we report the first experimental observation of a 'laboratory radiation belt' created in the Ring Trap 1 (RT-1) device. By spectroscopic measurement, we found an appreciable anisotropy in the ion temperature, proving the betatron acceleration mechanism which heats particles in the perpendicular direction with respect to the magnetic field when particles move inward. The energy balance model including the heating mechanism explains the observed ion temperature profile.

  13. APT accelerator. Topical report

    International Nuclear Information System (INIS)

    The Accelerator Production of Tritium (APT) project, sponsored by Department of Energy Defense Programs (DOE/DP), involves the preconceptual design of an accelerator system to produce tritium for the nation's stockpile of nuclear weapons. Tritium is an isotope of hydrogen used in nuclear weapons, and must be replenished because of radioactive decay (its half-life is approximately 12 years). Because the annual production requirements for tritium has greatly decreased since the end of the Cold War, an alternative approach to reactors for tritium production, based on a linear accelerator, is now being seriously considered. The annual tritium requirement at the time this study was undertaken (1992-1993) was 3/8 that of the 1988 goal, usually stated as 3/8-Goal. Continued reduction in the number of weapons in the stockpile has led to a revised (lower) production requirement today (March, 1995). The production requirement needed to maintain the reduced stockpile, as stated in the recent Nuclear Posture Review (summer 1994) is approximately 3/16-Goal, half the previous level. The Nuclear Posture Review also requires that the production plant be designed to accomodate a production increase (surge) to 3/8-Goal capability within five years, to allow recovery from a possible extended outage of the tritium plant. A multi-laboratory team, collaborating with several industrial partners, has developed a preconceptual APT design for the 3/8-Goal, operating at 75% capacity. The team has presented APT as a promising alternative to the reactor concepts proposed for Complex-21. Given the requirements of a reduced weapons stockpile, APT offers both significant safety, environmental, and production-fexibility advantages in comparison with reactor systems, and the prospect of successful development in time to meet the US defense requirements of the 21st Century

  14. VLHC accelerator physics

    Energy Technology Data Exchange (ETDEWEB)

    Michael Blaskiewicz et al.

    2001-11-01

    A six-month design study for a future high energy hadron collider was initiated by the Fermilab director in October 2000. The request was to study a staged approach where a large circumference tunnel is built that initially would house a low field ({approx}2 T) collider with center-of-mass energy greater than 30 TeV and a peak (initial) luminosity of 10{sup 34} cm{sup -2}s{sup -1}. The tunnel was to be scoped, however, to support a future upgrade to a center-of-mass energy greater than 150 TeV with a peak luminosity of 2 x 10{sup 34} cm{sup -2} sec{sup -1} using high field ({approx} 10 T) superconducting magnet technology. In a collaboration with Brookhaven National Laboratory and Lawrence Berkeley National Laboratory, a report of the Design Study was produced by Fermilab in June 2001. 1 The Design Study focused on a Stage 1, 20 x 20 TeV collider using a 2-in-1 transmission line magnet and leads to a Stage 2, 87.5 x 87.5 TeV collider using 10 T Nb{sub 3}Sn magnet technology. The article that follows is a compilation of accelerator physics designs and computational results which contributed to the Design Study. Many of the parameters found in this report evolved during the study, and thus slight differences between this text and the Design Study report can be found. The present text, however, presents the major accelerator physics issues of the Very Large Hadron Collider as examined by the Design Study collaboration and provides a basis for discussion and further studies of VLHC accelerator parameters and design philosophies.

  15. APT accelerator. Topical report

    Energy Technology Data Exchange (ETDEWEB)

    Lawrence, G.; Rusthoi, D. [comp.] [ed.

    1995-03-01

    The Accelerator Production of Tritium (APT) project, sponsored by Department of Energy Defense Programs (DOE/DP), involves the preconceptual design of an accelerator system to produce tritium for the nation`s stockpile of nuclear weapons. Tritium is an isotope of hydrogen used in nuclear weapons, and must be replenished because of radioactive decay (its half-life is approximately 12 years). Because the annual production requirements for tritium has greatly decreased since the end of the Cold War, an alternative approach to reactors for tritium production, based on a linear accelerator, is now being seriously considered. The annual tritium requirement at the time this study was undertaken (1992-1993) was 3/8 that of the 1988 goal, usually stated as 3/8-Goal. Continued reduction in the number of weapons in the stockpile has led to a revised (lower) production requirement today (March, 1995). The production requirement needed to maintain the reduced stockpile, as stated in the recent Nuclear Posture Review (summer 1994) is approximately 3/16-Goal, half the previous level. The Nuclear Posture Review also requires that the production plant be designed to accomodate a production increase (surge) to 3/8-Goal capability within five years, to allow recovery from a possible extended outage of the tritium plant. A multi-laboratory team, collaborating with several industrial partners, has developed a preconceptual APT design for the 3/8-Goal, operating at 75% capacity. The team has presented APT as a promising alternative to the reactor concepts proposed for Complex-21. Given the requirements of a reduced weapons stockpile, APT offers both significant safety, environmental, and production-fexibility advantages in comparison with reactor systems, and the prospect of successful development in time to meet the US defense requirements of the 21st Century.

  16. 2014 CERN Accelerator Schools

    CERN Multimedia

    2014-01-01

    A specialised school on Power Converters will be held in Baden, Switzerland, from 7 to 14 May 2014. Please note that the deadline for applications is 7 FEBRUARY 2014. A course on Introduction to Accelerator Physics will be held in Prague, Czech Republic, from 31 August to 12 September 2014. Applications are now open for this school; the application deadline is 25 APRIL 2014. Further information on these schools and other CAS events can be found on the CAS website and on the Indico page. For further information please contact Barbara.strasser@cern.ch

  17. Accelerating abelian gauge dynamics

    CERN Document Server

    Adler, Stephen Louis

    1991-01-01

    In this paper, we suggest a new acceleration method for Abelian gauge theories based on linear transformations to variables which weight all length scales equally. We measure the autocorrelation time for the Polyakov loop and the plaquette at β=1.0 in the U(1) gauge theory in four dimensions, for the new method and for standard Metropolis updates. We find a dramatic improvement for the new method over the Metropolis method. Computing the critical exponent z for the new method remains an important open issue.

  18. Accelerated Innovation Pilot

    Science.gov (United States)

    Davis, Jeffrey

    2012-01-01

    Opportunities: I. Engage NASA team (examples) a) Research and technology calls . provide suggestions to AES, HRP, OCT. b) Use NASA@Work to solicit other ideas; (possibly before R+D calls). II. Stimulate collaboration (examples) a) NHHPC. b) Wharton Mack Center for Technological Innovation (Feb 2013). c) International ] DLR ] :envihab (July 2013). d) Accelerated research models . NSF, Myelin Repair Foundation. III. Engage public Prizes (open platform: InnoCentive, yet2.com, NTL; Rice Business Plan, etc.) IV. Use same methods to engage STEM.

  19. Hardware Accelerated Power Estimation

    CERN Document Server

    Coburn, Joel; Raghunathan, Anand

    2011-01-01

    In this paper, we present power emulation, a novel design paradigm that utilizes hardware acceleration for the purpose of fast power estimation. Power emulation is based on the observation that the functions necessary for power estimation (power model evaluation, aggregation, etc.) can be implemented as hardware circuits. Therefore, we can enhance any given design with "power estimation hardware", map it to a prototyping platform, and exercise it with any given test stimuli to obtain power consumption estimates. Our empirical studies with industrial designs reveal that power emulation can achieve significant speedups (10X to 500X) over state-of-the-art commercial register-transfer level (RTL) power estimation tools.

  20. Medical applications of accelerators

    CERN Document Server

    Rossi, Sandro

    1998-01-01

    At Present, about five thousands accelerators are devoted to biomedical applications. They are mainly used in radiotherapy, research and medical radioisotopes production. In this framework oncological hadron-therapy deserves particular attention since it represents a field in rapid evolution thanks to the joint efforts of laboratories with long experiences in particle physics. It is the case of CERN where the design of an optimised synchrotron for medical applications has been pursued. These lectures present these activities with particular attention to the new developments which are scientifically interesting and/or economically promising.

  1. Mechanics of machinery

    CERN Document Server

    Mostafa, Mahmoud A

    2012-01-01

    MechanismsDefinitions Degrees of Freedom of Planar Mechanisms Four-Revolute-Pairs Chains Single-Slider Chain Double-Slider Mechanisms Mechanisms with Higher Pairs Compound Mechanisms Special Mechanisms Analytical Position Analysis of Mechanisms Velocities and AccelerationsAbsolute Plane Motion of a Particle Relative Motion Applications to Common Links Analysis of Mechanisms: Graphical Method Method of Instantaneous Centers for Determining the VelocitiesAnalytical Analysis CamsIntroduction Types of Cams Modes of Input/Output Motion Follower Configurations Classes of Cams Spur GearsIntroduction

  2. Acceleration without Temperature

    CERN Document Server

    Doria, Alaric

    2015-01-01

    We show that while some non-uniformly accelerating observers (NUAOs) do indeed see a Bose-Einstein distribution of particles for the expectation value of the number operator in the Minkowski vacuum state, the density matrix is non-thermal and therefore a definition of temperature is not warranted. This is due to the fact that our NUAOs do not see event horizons in the spacetime. More specifically, the Minkowski vacuum state is perceived by our NUAOs as a single-mode squeezed state as opposed to the two-mode squeezed state characteristic of uniformly accelerating observers. Both single and two-mode squeezed states are pure quantum states; however, tracing over degrees of freedom in one of the modes of the two-mode squeezed state reduces the pure density matrix to a thermal density matrix. It is this property in the two-mode squeezed state that allows one to consistently define a temperature. In the single-mode case, an equivalent tracing is neither required nor available.

  3. Accelerator School Success

    CERN Document Server

    2004-01-01

    Accelerator specialists don't grow on trees: training them is the job of the CERN Accelerator School (CAS). Group photo during visit to the Daresbury Laboratory. CAS and the CCLRC Daresbury Laboratory jointly organised a specialised school on Power Converters in Warrington, England from 12-18 May 2004. The last CAS Power Converter course was in 1990, so there was plenty of ground to cover. The challenging programme proposed a review of the state of the art and the latest developments in the field, including 30 hours of tuition. The school also included a visit to the CCLRC Daresbury laboratory, a one-day excursion to Liverpool and Chester and a themed (Welsh medieval) dinner at the school's closure. A record attendance of 91 students of more than 20 different nationalities included not only participants from Europe and North America but also from Armenia, Taiwan, India, Turkey, Iran and for the first time, fee-paying students from China and Australia. European industry showed a welcome and solid interest in...

  4. Design Considerations for Plasma Accelerators Driven by Lasers or Particle Beams

    OpenAIRE

    Schroeder, C. B.

    2011-01-01

    Plasma accelerators may be driven by the ponderomotive force of an intense laser or the space-charge force of a charged particle beam. The implications for accelerator design and the different physical mechanisms of laser-driven and beam-driven plasma acceleration are discussed. Driver propagation is examined, as well as the effects of the excited plasma wave phase velocity. The driver coupling to subsequent plasma accelerator stages for high-energy physics applications is addressed.

  5. 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...

  6. 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

  7. Acceleration in Linear and Circular Motion

    Science.gov (United States)

    Kellington, S. H.; Docherty, W.

    1975-01-01

    Describes the construction of a simple accelerometer and explains its use in demonstrating acceleration, deceleration, constant speed, measurement of acceleration, acceleration and the inclined plane and angular and radial acceleration. (GS)

  8. Accelerated growth of calcium silicate hydrates: Experiments and simulations

    International Nuclear Information System (INIS)

    Despite the usefulness of isothermal calorimetry in cement analytics, without any further computations this brings only little information on the nucleation and growth of hydrates. A model originally developed by Garrault et al. is used in this study in order to simulate hydration curves of cement obtained by calorimetry with different known hardening accelerators. The limited basis set of parameters used in this model, having a physical or chemical significance, is valuable for a better understanding of mechanisms underlying in the acceleration of C-S-H precipitation. Alite hydration in presence of four different types of hardening accelerators was investigated. It is evidenced that each accelerator type plays a specific role on one or several growth parameters and that the model may support the development of new accelerators. Those simulations supported by experimental observations enable us to follow the formation of the C-S-H layer around grains and to extract interesting information on its apparent permeability.

  9. Generation and transport of laser accelerated ion beams

    International Nuclear Information System (INIS)

    Currently the LIGHT- Project (Laser Ion Generation, Handling and Transport) is performed at the GSI Helmholtzzentrum fuer Schwerionenforschung GmbH Darmstadt. Within this project, intense proton beams are generated by laser acceleration, using the TNSA mechanism. After the laser acceleration the protons are transported through the beam pipe by a pulsed power solenoid. To study the transport a VORPAL 3D simulation is compared with CST simulation. A criterion as a function of beam parameters was worked out, to rate the importance of space charge. Furthermore, an exemplary comparison of the solenoid with a magnetic quadrupole-triplet was carried out. In the further course of the LIGHT-Project, it is planned to generate ion beams with higher kinetic energies, using ultra-thin targets. The acceleration processes that can appear are: RPA (Radiation Pressure Acceleration) and BOA (Break-Out Afterburner). Therefore the transport of an ion distribution will be studied, as it emerges from a RPA acceleration.

  10. Estimation of direct laser acceleration in laser wakefield accelerators using particle-in-cell simulations

    CERN Document Server

    Shaw, J L; Marsh, K A; Tsung, F S; Mori, W B; Joshi, C

    2015-01-01

    Many current laser wakefield acceleration (LWFA) experiments are carried out in a regime where the laser pulse length is on the order of or longer than the wake wavelength and where ionization injection is employed to inject electrons into the wake. In these experiments, the trapped electrons will co-propagate with the longitudinal wakefield and the transverse laser field. In this scenario, the electrons can gain a significant amount of energy from both the direct laser acceleration (DLA) mechanism as well as the usual LWFA mechanism. Particle-in-cell (PIC) codes are frequently used to discern the relative contribution of these two mechanisms. However, if the longitudinal resolution used in the PIC simulations is inadequate, it can produce numerical heating that can overestimate the transverse motion, which is important in determining the energy gain due to DLA. We have therefore carried out a systematic study of this LWFA regime by varying the longitudinal resolution of PIC simulations from the standard, bes...

  11. Investigation on laser accelerators. Plasma beat wave accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Miura, Akihiko; Miyamoto, Yasuaki; Hagiwara, Masayoshi; Suzuki, Mitsutoshi; Sudo, Osamu [Power Reactor and Nuclear Fuel Development Corp., Tokai, Ibaraki (Japan). Tokai Works

    1998-04-01

    Laser accelerator technology has characteristics of high energy, compact, short pulse and high luminescence{center_dot}low emittance. This means potential many applications in wide ranges of fields as well as high energy and nuclear physics. High power short laser pulses are injected to a plasma in the typical example of laser accelerators. Large electric fields are induced in the plasma. Electrons in the plasma are accelerated with the ponderomotive force of the electric field. The principles of interaction on beat wave, wakefield accelerators, inverse free electron laser and inverse Cherenkov radiation are briefly introduced. The overview of plasma beat wave accelerator study is briefly described on the programs at Chalk River Laboratories(Canada), UCLA(USA), Osaka Univ. (Japan) and Ecole Polytechnique (France). Issues of the plasma beat wave accelerator are discussed from the viewpoint of application. Existing laser technologies of CO{sub 2}, YAG and YFL are available for the present day accelerator technology. An acceleration length of beat wave interaction is limited due to its phase condition. Ideas on multi-staged acceleration using the phasing plasma fiber are introduced. (Y. Tanaka)

  12. 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/

  13. 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/

  14. Vacuum system for Advanced Test Accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Denhoy, B.S.

    1981-09-03

    The Advanced Test Accelerator (ATA) is a pulsed linear electron beam accelerator designed to study charged particle beam propagation. ATA is designed to produce a 10,000 amp 50 MeV, 70 ns electron beam. The electron beam acceleration is accomplished in ferrite loaded cells. Each cell is capable of maintaining a 70 ns 250 kV voltage pulse across a 1 inch gap. The electron beam is contained in a 5 inch diameter, 300 foot long tube. Cryopumps turbomolecular pumps, and mechanical pumps are used to maintain a base pressure of 2 x 10/sup -6/ torr in the beam tube. The accelerator will be installed in an underground tunnel. Due to the radiation environment in the tunnel, the controlling and monitoring of the vacuum equipment, pressures and temperatures will be done from the control room through a computer interface. This paper describes the vacuum system design, the type of vacuum pumps specified, the reasons behind the selection of the pumps and the techniques used for computer interfacing.

  15. Multi-stage magnetic induction mass accelerator

    International Nuclear Information System (INIS)

    The magnetic induction method of mass acceleration readily lends itself to multi-staging. In the limit of many stages, such an accelerator approaches a distributed energy source system where only closing switches are necessary. We describe the design and performance of a three-stage accelerator, each driven by a separate capacitor bank. This system was modeled using a previously reported computer code. In order to do this the code was modified to calculate projectile acceleration through a succession of driver coils: Thermal conductivity and surface melting models were also added. The former is necessary due to the extended transit time through many stages. The latter is needed in anticipation of the more extreme ohmic heating when the capacitor banks are replaced by explosive-driven, magnetic flux compression generators. The performance goal of this system is to at least double the kinetic energy of a 0.3 kgm copperclad, steel projectile injected at a velocity of 300 m/sec from an explosive-driven gun. We then plan to test the system at the thermal and mechanical limit by using explosive-driven, magnetic flux compression generators as energy sources. We envision a six-stage system driven by three generators

  16. 36Chlorine accelerator mass spectrometry programme at BARC-TIFR pelletron accelerator. RSP-12

    International Nuclear Information System (INIS)

    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 36Cl and 129I. Cosmogenic radio isotope 36Cl is widely being detected using AMS as it has got applications in ground water research, radioactive waste management, atmospheric 36Cl transport mechanism studies of Arctic Alpine ice core etc. As a part of the ongoing AMS programme at 14UD Pelletron Accelerator Facility, Mumbai, a segmented gas detector developed for identification of 36Cl was tested for performance. Recently a beam chopper required for this measurement has been developed. 36Cl measurements carried out to detect and measure the ratio of 36Cl to 35Cl in an irradiated sample and dated sample are reported in this paper

  17. Lectures in accelerator theory

    International Nuclear Information System (INIS)

    Lecture I deals with the behavior of particles in the nonlinear field arising from the electromagnetic interaction of colliding beams. The case treated, that of counter-rotating proton beams crossing each other at a non-zero angle, has the simple feature that the force between the beam is one dimensional. In lecture II, an analysis of the development of traveling waves on particle beams is presented. The situation studied is that of a uniform beam current in a circular accelerator and the excitation for the coherent motion is induced by the resistivity of the vacuum chamber wall. Finally, in lecture III, a description of the current accumulation process used at the proton storage rings at CERN (The ISR) is given. Particle pulses of rather low average current are injected and stored along the length and width of the vacuum chamber. The efficiency is very high and large currents (over 40 amperes) have been achieved

  18. Accelerator vacuum system elements

    International Nuclear Information System (INIS)

    Some elements of vacuum systems are investigated. Considerable attention has been given to the investigation into peculiarities in pumping out of a ionoguide for transportation of an accelerated charged particles beam the spread of which often attains a considerable length. The number of pumps over the ionoguide length is experimentally determined. It is shown that as a result of ionoguide warm-up the pumping out time is considerably reduced maximum permissible pressure is decreased by two orders and lesser rate of pump pumping out is required. The investigations have shown that when operating the ionoguide there is no necessity in setting up seals between the ionoguide and magnetodischarged pump. The causes of the phenomenon in which the pressure near the pump is greater than in the end of the ionoguide, are impurities carried in by the pump into the ionoguide volume and the pumping out capacity of the pressure converter

  19. ACCELERATING NANO-TECHNOLOGICAL

    DEFF Research Database (Denmark)

    Jensen, Jens Stissing; Koch, Christian

    2007-01-01

    By viewing the construction industry as a technological innovation system (TIS) this paper discusses possible initiatives to accelerate nanotechnological innovations. The point of departure is a recent report on the application of nano-technology in the Danish construction industry, which concludes...... of the system are furthermore poorly equipped at identifying potentials within high-tech areas. In order to exploit the potentials of nano-technology it is thus argued that an alternative TIS needs to be established. Initiatives should identify and support “incubation rooms” or marked niches in order...... for the different elements of the TIS to evolve. This could involve nano-visioning including scenarios of future technological applications and industrial dynamics....

  20. Testing Gravity on Accelerators

    CERN Document Server

    Kalaydzhyan, Tigran

    2016-01-01

    Weak equivalence principle (WEP) is one of the cornerstones of the modern theories of gravity, stating that the trajectory of a freely falling test body is independent of its internal structure and composition. Even though WEP is known to be valid for the normal matter with a high precision, it has never been experimentally confirmed for relativistic matter and antimatter. We make an attempt to constrain possible deviations from WEP utilizing the modern accelerator technologies. We analyze the (absence of) vacuum Cherenkov radiation, photon decay, anomalous synchrotron losses and the Compton spectra to put limits on the isotropic Lorentz violation and further convert them to the constraints on the difference between the gravitational and inertial masses of the relativistic electrons/positrons. Our main result is the 0.1% limit on the mentioned difference.

  1. Self-accelerated Universe

    CERN Document Server

    Kosyakov, B P

    2005-01-01

    It is widely believed that the large redshifts for distant supernovae are explained by the vacuum energy dominance, or, in other words, by the cosmological constant in Einstein's equations, which is responsible for the anti-gravitation effect. A tacit assumption is that particles move along a geodesic for the background metric. This is in the same spirit as the consensus regarding the uniform Galilean motion of a free electron. However, there is a runaway solution to the Lorentz--Dirac equation governing the behavior of a radiating electron, in addition to the Galilean solution. Likewise, a runaway solution to the entire system of equations, both gravitation and matter equations of motion including, may provide an alternative explanation for the accelerated expansion of the Universe, without recourse to the hypothetic cosmological constant.

  2. The entangled accelerating universe

    CERN Document Server

    González-Díaz, Pedro F

    2009-01-01

    Using the known result that the nucleation of baby universes in correlated pairs is equivalent to spacetime squeezing, we show in this letter that there exists a T-duality symmetry between two-dimensional warp drives, which are physically expressible as localized de Sitter little universes, and two dimensional Tolman-Hawking and Gidding-Strominger baby universes respectively correlated in pairs, so that the creation of warp drives is also equivalent to spacetime squeezing. Perhaps more importantly, it has been also seen that the nucleation of warp drives entails a violation of the Bell's inequalities, and hence the phenomena of quantum entanglement, complementarity and wave function collapse. These results are generalized to the case of any dynamically accelerating universe filled with dark or phantom energy whose creation is also physically equivalent to spacetime squeezing and to the violation of the Bell's inequalities, so that the universe we are living in should be governed by essential sharp quantum the...

  3. SPS accelerating cavity

    CERN Multimedia

    1976-01-01

    The SPS started up with 2 accelerating cavities (each consisting of 5 tank sections) in LSS3. They have a 200 MHz travelling wave structure (see 7411032 and 7802190) and 750 kW of power is fed to each of the cavities from a 1 MW tetrode power amplifier, located in a surface building above, via a coaxial transmission line. Clemens Zettler, builder of the SPS RF system, is standing at the side of one of the cavities. In 1978 and 1979 another 2 cavities were added and entered service in 1980. These were part of the intensity improvement programme and served well for the new role of the SPS as proton-antiproton collider. See also 7411032, 8011289, 8104138, 8302397.

  4. Accelerator Technology for the Mankind

    CERN Document Server

    Sultansoy, S

    2006-01-01

    Particle accelerators technology is one of the generic technologies which is locomotive of the development in almost all fields of science and technology. According to the U.S. Department of Energy: "Accelerators underpin every activity of the Office of Science and, increasingly, of the entire scientific enterprise. From biology to medicine, from materials to metallurgy, from elementary particles to the cosmos, accelerators provide the microscopic information that forms the basis for scientific understanding and applications. The combination of ground and satellite based observatories and particle accelerators will advance our understanding of our world, our galaxy, our universe, and ourselves." Because of this, accelerator technology should become widespread all over the world. Existing situation shows that a large portion of the world, namely the South and Mid-East, is poor on the accelerator technology. UNESCO has recognized this deficit and started SESAME project in Mid-East, namely Jordan. Turkic Acceler...

  5. Electrostatic accelerators fundamentals and applications

    CERN Document Server

    2005-01-01

    Electrostatic accelerators are an important and widespread subgroup within the broad spectrum of modern, large particle acceleration devices. They are specifically designed for applications that require high-quality ion beams in terms of energy stability and emittance at comparatively low energies (a few MeV). Their ability to accelerate virtually any kind of ion over a continuously tunable range of energies make them a highly versatile tool for investigations in many research fields including, but not limited to, atomic and nuclear spectroscopy, heavy ion reactions, accelerator mass spectroscopy as well as ion-beam analysis and modification. The book is divided into three parts. The first part concisely introduces the field of accelerator technology and techniques that emphasize their major modern applications. The second part treats the electrostatic accelerator per se: its construction and operational principles as well as its maintenance. The third part covers all relevant applications in which electrosta...

  6. Accelerating Universe and Event Horizon

    OpenAIRE

    He, Xiao-Gang(INPAC, SKLPPC and Department of Physics, Shanghai Jiao Tong University, Shanghai, China)

    2001-01-01

    It has been argued in the literature that if a universe is expanding with an accelerating rate indefinitely, it presents a challenge to string theories due to the existence of event horizons. We study the fate of a currently accelerating universe. We show that the universe will continue to accelerate indefinitely if the parameter $\\omega = p/\\rho$ of the equation of state is a constant, no matter how many different types of energy (matter, radiation, quintessence, cosmological constant and et...

  7. Project X: Accelerator Reference Design

    CERN Document Server

    Holmes, S D; Chase, B; Gollwitzer, K; Johnson, D; Kaducak, M; Klebaner, A; Kourbanis, I; Lebedev, V; Leveling, A; Li, D; Nagaitsev, S; Ostroumov, P; Pasquinelli, R; Patrick, J; Prost, L; Scarpine, V; Shemyakin, A; Solyak, N; Steimel, J; Yakovlev, V; Zwaska, R

    2013-01-01

    Part 1 of "Project X: Accelerator Reference Design, Physics Opportunities, Broader Impacts". Part 1 contains the volume Preface and a description of the conceptual design for a high-intensity proton accelerator facility being developed to support a world-leading program of Intensity Frontier physics over the next two decades at Fermilab. Subjects covered include performance goals, the accelerator physics design, and the technological basis for such a facility.

  8. Stationary plasma accelerator - ATON engine

    International Nuclear Information System (INIS)

    The principles of a stationary plasma accelerator (engine) with closed electron drift are described. The accelerator has record integral characteristics. A method for analysis of operating process features in the integral characteristics is proposed. Results are presented of local measurements of the plasma parameters in the accelerator channel and in the leaving plasma jet Main attention is paid to determination of the part of twice ionized ions in the plasma flow

  9. Accelerator control systems in China

    International Nuclear Information System (INIS)

    Three accelerator facilities were built in the past few years, the 2.8 GeV electron positron collider BEPC, the heavy ion SSC cyclotron accelerator HIRFL and the 800 MeV synchrotron radiation storage ring HESYRL. Aimed at different research areas, they represent a new generation of accelerator in China. This report describes the design philosophy, the structure, performance as well as future improvements of the control systems of the these facilities. (author)

  10. Accelerator science in medical physics

    OpenAIRE

    Peach, K.; Wilson, P.; Jones, B

    2011-01-01

    The use of cyclotrons and synchrotrons to accelerate charged particles in hospital settings for the purpose of cancer therapy is increasing. Consequently, there is a growing demand from medical physicists, radiographers, physicians and oncologists for articles that explain the basic physical concepts of these technologies. There are unique advantages and disadvantages to all methods of acceleration. Several promising alternative methods of accelerating particles also have to be considered sin...

  11. Accelerators for research and applications

    International Nuclear Information System (INIS)

    The newest particle accelerators are almost always built for extending the frontiers of research, at the cutting edge of science and technology. Once these machines are operating and these technologies mature, new applications are always found, many of which touch our lives in profound ways. The evolution of accelerator technologies will be discussed, with descriptions of accelerator types and characteristics. The wide range of applications of accelerators will be discussed, in fields such as nuclear science, medicine, astrophysics and space-sciences, power generation, airport security, materials processing and microcircuit fabrication. 13 figs

  12. Maximal acceleration and radiative processes

    OpenAIRE

    Papini, Giorgio

    2015-01-01

    We derive the radiation characteristics of an accelerated, charged particle in a model due to Caianiello in which the proper acceleration of a particle of mass $m$ has the upper limit $\\mathcal{A}_m=2mc^3/\\hbar$. We find two power laws, one applicable to lower accelerations, the other more suitable for accelerations closer to $\\mathcal{A}_m$ and to the related physical singularity in the Ricci scalar. Geometrical constraints and power spectra are also discussed. By comparing the power laws du...

  13. Thomas Precession by Uniform Acceleration

    CERN Document Server

    Pardy, Miroslav

    2015-01-01

    We determine the nonlinear transformations between coordinate systems which are mutually in a constant symmetrical accelerated motion. The maximal acceleration limit follows from the kinematical origin and it is an analogue of the maximal velocity in special relativity. We derive the dependence of mass, length, time, Doppler effect, Cherenkov effect and transition radiation angle on acceleration as an analogue phenomena in special theory of relativity. The last application of our method is the Thomas precession by uniform acceleration with the possible role in the modern physics and cosmology. The comparison of derived results with other relativistic methods is necessary.

  14. Superconducting Radiofrequency (SRF) Acceleration Technology

    Data.gov (United States)

    Federal Laboratory Consortium — SRF cavities enable accelerators to increase particle beam energy levels while minimizing the use of electrical power by all but eliminating electrical resistance....

  15. Controlled rolling and accelerated cooling of steel

    Energy Technology Data Exchange (ETDEWEB)

    Ranta, H.; Korhonen, A.S.; Partinen, S.

    1993-12-31

    The subproject `Controlled Rolling and Cooling of Steel` was carried out at the Helsinki University of Technology in the Laboratory of Processing and Heat Treatment of Materials during the years 1989-91. The work described here was a part of a SULA-project. The aim of the project at the Helsinki University of Technology was to study controlled rolling and accelerated cooling and the temperature and strain distributions in the steel during rolling. Modelling of accelerated cooling is important in ensuring that the desired shape and mechanical properties of steel are obtained without additional heat treatment. When no additional heat treatments are needed after the rolling process, it is possible to increase the volume of production and to save time and money. Mathematical models were studied and developed to describe the processes and to make it possible to predict the shape and mechanical properties of the final product. Models are also needed to study the influence of various processing parameters. Since full-scale experiments are expensive, a laboratory-scale cooling line for hot rolling experiments was constructed. During this project numerous hot forming and accelerated cooling experiments were carried out

  16. Intense ion beams accelerated by relativistic laser plasmas

    Science.gov (United States)

    Roth, Markus; Cowan, Thomas E.; Gauthier, Jean-Claude J.; Allen, Matthew; Audebert, Patrick; Blazevic, Abel; Fuchs, Julien; Geissel, Matthias; Hegelich, Manuel; Karsch, S.; Meyer-ter-Vehn, Jurgen; Pukhov, Alexander; Schlegel, Theodor

    2001-12-01

    We have studied the influence of the target properties on laser-accelerated proton and ion beams generated by the LULI multi-terawatt laser. A strong dependence of the ion emission on the surface conditions, conductivity, shape and material of the thin foil targets were observed. We have performed a full characterization of the ion beam using magnetic spectrometers, Thompson parabolas, radiochromic film and nuclear activation techniques. The strong dependence of the ion beam acceleration on the conditions on the target back surface was found in agreement with theoretical predictions based on the target normal sheath acceleration (TNSA) mechanism. Proton kinetic energies up to 25 MeV have been observed.

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

    International Nuclear Information System (INIS)

    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 36Cl and 129I. Cosmogenic radioisotope 36Cl is widely being detected using AMS as it has got applications in ground water research, radioactive waste management, atmospheric 36Cl 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 14C from a charcoal sample and 3He in natural Helium. As the primary interest of AMS programme at Mumbai Pelletron Accelerator is related to the cosmogenic nuclei, 36Cl and 129I, a segmented gas detector developed for identification of 36Cl was tested for performance. Recently a beam chopper required for this measurement has also been developed

  18. Investigation of toroidal acceleration and potential acceleration forces in EAST and J-TEXT plasmas

    CERN Document Server

    Wang, Fudi; Pan, Xiayun; Cheng, Zhifeng; Chen, Jun; Cao, Guangming; Wang, Yuming; Han, Xiang; Li, Hao; Wu, Bin; Chen, Zhongyong; Bitter, Manfred; Hill, Kenneth; Rice, John; Morita, Shigeru; Li, Yadong; Zhuang, Ge; Ye, Minyou; Wan, Baonian; Shi, Yuejiang

    2014-01-01

    In order to produce intrinsic rotation, bulk plasmas must be collectively accelerated by the net force exerted on them, which results from both driving and damping forces. So, to study the possible mechanisms of intrinsic rotation generation, it is only needed to understand characteristics of driving and damping terms because the toroidal driving and damping forces induce net acceleration which generates intrinsic rotation. Experiments were performed on EAST and J-TEXT for ohmic plasmas with net counter- and co-current toroidal acceleration generated by density ramping up and ramping down. Additionally on EAST, net co-current toroidal acceleration was also formed by LHCD or ICRF. For the current experimental results, toroidal acceleration was between - 50 km/s^2 in counter-current direction and 70 km/s^2 in co-current direction. According to toroidal momentum equation, toroidal electric field (E\\-(\\g(f))), electron-ion toroidal friction, and toroidal viscous force etc. may play roles in the evolution of toroi...

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

    International Nuclear Information System (INIS)

    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.)

  20. Optimizing laser-driven proton acceleration from overdense targets

    Science.gov (United States)

    Stockem Novo, A.; Kaluza, M. C.; Fonseca, R. A.; Silva, L. O.

    2016-01-01

    We demonstrate how to tune the main ion acceleration mechanism in laser-plasma interactions to collisionless shock acceleration, thus achieving control over the final ion beam properties (e. g. maximum energy, divergence, number of accelerated ions). We investigate this technique with three-dimensional particle-in-cell simulations and illustrate a possible experimental realisation. The setup consists of an isolated solid density target, which is preheated by a first laser pulse to initiate target expansion, and a second one to trigger acceleration. The timing between the two laser pulses allows to access all ion acceleration regimes, ranging from target normal sheath acceleration, to hole boring and collisionless shock acceleration. We further demonstrate that the most energetic ions are produced by collisionless shock acceleration, if the target density is near-critical, ne ≈ 0.5 ncr. A scaling of the laser power shows that 100 MeV protons may be achieved in the PW range. PMID:27435449

  1. Optimizing laser-driven proton acceleration from overdense targets

    Science.gov (United States)

    Stockem Novo, A.; Kaluza, M. C.; Fonseca, R. A.; Silva, L. O.

    2016-07-01

    We demonstrate how to tune the main ion acceleration mechanism in laser-plasma interactions to collisionless shock acceleration, thus achieving control over the final ion beam properties (e. g. maximum energy, divergence, number of accelerated ions). We investigate this technique with three-dimensional particle-in-cell simulations and illustrate a possible experimental realisation. The setup consists of an isolated solid density target, which is preheated by a first laser pulse to initiate target expansion, and a second one to trigger acceleration. The timing between the two laser pulses allows to access all ion acceleration regimes, ranging from target normal sheath acceleration, to hole boring and collisionless shock acceleration. We further demonstrate that the most energetic ions are produced by collisionless shock acceleration, if the target density is near-critical, ne ≈ 0.5 ncr. A scaling of the laser power shows that 100 MeV protons may be achieved in the PW range.

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

    International Nuclear Information System (INIS)

    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.)

  3. Prototype of cavity for lepton acceleration in the SPS

    CERN Multimedia

    1982-01-01

    The SPS was to be the injector for LEP and had to accelerate the electrons and positrons delivered by the PS. This is a prototype of a 200 MHz, single-cell, standing-wave, cavity for lepton acceleration in the SPS. On top of the cavity, at the back, is the tetrode amplifier, the tuning mechanism is leaning towards the viewer. See also 8103523 and Annual Report 1981, p.114.

  4. "Super-acceleration" of ions in a stationary plasma discharge

    Science.gov (United States)

    Bardakov, Vladimir; Ivanov, Sergey; Kazantsev, Alexander; Strokin, Nikolay; Stupin, Aleksey

    2016-10-01

    We report on the detection of the acceleration effect of the bulk of ions in a stationary plasma E × B discharge to energies exceeding considerably the value equivalent to the discharge voltage. We determined the conditions necessary for the generation of high-energy ions, and ascertained the influence exerted on the value of the ion energies by pressure (flow rate) and the kind of plasma-producing gas, and by the value of discharge current. The possible acceleration mechanism is suggested.

  5. Laser Wakefield Acceleration of Electrons at Ecole Polytechnique

    CERN Document Server

    Amiranoff, F; Bernard, D; Cros, B; Descamps, D; Dorchies, F; Jacquet, F; Malka, V; Marquès, J; Matthieussent, G; Miné, P; Modena, A; Mora, P; Morillo, J; Najmudin, Z

    1999-01-01

    The acceleration of electrons injected in a plasma wave generated by the laser wakefield mechanism has been observed. A maximum energy gain of 1.6 eV has been measured and the maximum longitudinal electric field is estimated to 1.5~GV/m. The experimental data agree with theoretical predictions when 3D effects are taken into account. The duration of the plasma wave inferred from the number of accelerated electrons is of the order of 1 ps.

  6. Accelerating scientific publication in biology.

    Science.gov (United States)

    Vale, Ronald D

    2015-11-01

    Scientific publications enable results and ideas to be transmitted throughout the scientific community. The number and type of journal publications also have become the primary criteria used in evaluating career advancement. Our analysis suggests that publication practices have changed considerably in the life sciences over the past 30 years. More experimental data are now required for publication, and the average time required for graduate students to publish their first paper has increased and is approaching the desirable duration of PhD training. Because publication is generally a requirement for career progression, schemes to reduce the time of graduate student and postdoctoral training may be difficult to implement without also considering new mechanisms for accelerating communication of their work. The increasing time to publication also delays potential catalytic effects that ensue when many scientists have access to new information. The time has come for life scientists, funding agencies, and publishers to discuss how to communicate new findings in a way that best serves the interests of the public and the scientific community.

  7. Accelerator experiments for the unification

    International Nuclear Information System (INIS)

    The spectrum of the elementary particles known today sets the scale of our future explorations. It is dominated in the boson sector by the W-Z triplet, mw = 80.2 ± 0.2 GeV and mz = 91.189 ± 0.004 GeV, and in the fermion sector by the top quark, ml =175.5 ± 5.1 GeV. Supersymmetric models imply the existence of many undiscovered particles that would be the partners of the particles, which we know today. Most models predict that several of them should populate the 100 - 1000 GeV mass ranges in which the Higgs mechanism is expected to operate. Our current knowledge of the particle world points to a mass range extending typically an order of magnitude above the W-Z mass for future exploration. In order to reach the large mass at which we target, the new accelerators must be operated in the collider mode rather than in the fixed target mode. In practice pp and e+e- colliders are only the tools able to reach such luminosity. Synchrotron radiation losses prevent the operation of e+e- colliders above the LEP-2 energy range (80 GeV). In pp case, synchrotron radiation losses remain small and a circular design can be maintained. (author)

  8. Accelerated dry curing of hams.

    Science.gov (United States)

    Marriott, N G; Kelly, R F; Shaffer, C K; Graham, P P; Boling, J W

    1985-01-01

    Uncured pork legs from the right side of 18 carcasses were treated with a Ross Tenderizer and the left side were controls. All 36 samples were dry-cured for 40, 56 or 70 days and evaluated for appearance traits, cure penetration characteristics, microbial load, Kramer Shear force and taste attributes. The tenderization treatment had no effect (P > 0·05) on visual color or cure penetration rate, weight loss before curing, percentage moisture, nitrate level, nitrite level, total plate count, anaerobic counts, psychrotrophic counts, objective and subjective tenderness measurements or juiciness. However, the higher values of salt suggested a possible acceleration of the dry cure penetration process among the tenderized samples. Cure time had no effect (P > 0·05) on percentage moisture, percentage salt, nitrate content, nitrite content, shear force and juiciness. Results suggest a limited effect of the mechanical tenderization process on certain traits related to dry curing and that total process time should be at least 70 days if color stability during cooking is desired. PMID:22056076

  9. CAS CERN Accelerator School: Second general accelerator physics course

    International Nuclear Information System (INIS)

    The course on general accelerator physics given at Aarhus is basically a repeat of that organised by the CERN Accelerator School at Gif-sur-Yvette, Paris in September 1984 and whose proceedings were published as CERN Yellow Report 85-19 (1985). However, the opportunity was taken to improve or extend certain subjects while introducing new ones and it is these which are included in the present proceedings. The lectures treated here include accelerator optics, insertions, image and space charge forces, neutralisation, diagnostics and intra-beam scattering while the seminar programme includes a number of specialised accelerator topics. Reports on a separate series of seminars organised by the University of Aarhus, Denmark, and devoted to advanced technology arising from general accelerator physics are also included, as well as errata to CERN 85-19. (orig.)

  10. CAS CERN Accelerator School superconductivity in particle accelerators

    International Nuclear Information System (INIS)

    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.)

  11. 加速器二极磁体的应力和磁场分析%Analysis of Mechanical Stress and Magnetic Field in Nuclotron Dipole Magnet for GSI Accelerator

    Institute of Scientific and Technical Information of China (English)

    王秋良; Gebhard Moritz

    2004-01-01

    A mechanical analysis of the Nuclotron dipole magnet is carried out using ANSYS Finite Element Method. It is used to evaluate the stress in the magnet at full field of 2 Tesla. A magneto-mechanical model for the dipole was developed using the program ANSYS and employed to compute the mechanical state of the coil under pressure and under Lorentz forces at nominal field. The results of a parametric study where the dimensions of several components were altered are used to estimate the impact of fabrication tolerances and assembly procedures on the final mechanical state of the magnet.%在本论文中,我们发展了磁机械耦合的ANSYS分析方法,使用有限元方法研究了加速器二极磁体的应力特性,通过数值模拟,我们研究了超导加速器磁体在磁体装配,冷却和运行磁场为2T时的应力.研究的结果将用于评估超导加速器磁体在建造和运行时的应力控制.

  12. Online modeling of the Fermilab accelerators

    International Nuclear Information System (INIS)

    We have implemented access to beam physics models of the Fermilab accelerators and beamlines through the Fermilab control system. The models run on Unix workstations, communicating with legacy controls software through a front end redirection mechanism (the open access server), a relational database and a simple text-based protocol over TCP/IP. The clients and the server are implemented in object-oriented C++. We discuss limitations of our approach and the difficulties that arise from it. Some of the obstacles may be overcome by introducing a new layer of abstraction. To maintain compatibility with the next generation of accelerator control software currently under development at the laboratory, this layer would be implemented in Java. We discuss the implications of that choice

  13. Accelerator based atomic physics experiments: an overview

    International Nuclear Information System (INIS)

    Atomic Physics research with beams from accelerators has continued to expand and the number of papers and articles at meetings and in journals reflects a steadily increasing interest and an increasing support from various funding agencies. An attempt will be made to point out where interdisciplinary benefits have occurred, and where applications of the new results to engineering problems are expected. Drawing from material which will be discussed in the conference, a list of the most active areas of research is presented. Accelerator based atomic physics brings together techniques from many areas, including chemistry, astronomy and astrophysics, nuclear physics, solid state physics and engineering. An example is the use of crystal channeling to sort some of the phenomena of ordinary heavy ion stopping powers. This tool has helped us to reach a better understanding of stopping mechanisms with the result that now we have established a better base for predicting energy losses of heavy ions in various materials

  14. On the safety of ITER accelerators.

    Science.gov (United States)

    Li, Ge

    2013-01-01

    Three 1 MV/40A accelerators in heating neutral beams (HNB) are on track to be implemented in the International Thermonuclear Experimental Reactor (ITER). ITER may produce 500 MWt of power by 2026 and may serve as a green energy roadmap for the world. They will generate -1 MV 1 h long-pulse ion beams to be neutralised for plasma heating. Due to frequently occurring vacuum sparking in the accelerators, the snubbers are used to limit the fault arc current to improve ITER safety. However, recent analyses of its reference design have raised concerns. General nonlinear transformer theory is developed for the snubber to unify the former snubbers' different design models with a clear mechanism. Satisfactory agreement between theory and tests indicates that scaling up to a 1 MV voltage may be possible. These results confirm the nonlinear process behind transformer theory and map out a reliable snubber design for a safer ITER.

  15. Propane Clathrate Hydrate Formation Accelerated by Methanol.

    Science.gov (United States)

    Amtawong, Jaruwan; Guo, Jin; Hale, Jared S; Sengupta, Suvrajit; Fleischer, Everly B; Martin, Rachel W; Janda, Kenneth C

    2016-07-01

    The role of methanol as both an inhibitor and a catalyst for the formation of clathrate hydrates (CHs) has been a topic of intense study. We report a new quantitative study of the kinetics of propane CH formation at 253 K from the reaction of propane gas with ice particles that have been doped with varying amounts of methanol. We find that methanol significantly accelerates the formation reaction with quite small doping quantities. Even for only 1 methanol molecule per 10 000 water molecules, the maximum uptake rate of propane into CHs is enhanced and the initiation pressure is reduced. These results enable more efficient production of CHs for gas storage. This remarkable acceleration of the CH formation reaction by small quantities of methanol may place constraints on the mechanism of the inhibition effect observed under other conditions, usually employing much larger quantities of methanol. PMID:27275862

  16. Electron Acceleration by Multi-Island Coalescence

    CERN Document Server

    Oka, M; Krucker, S; Fujimoto, M; Shinohara, I

    2010-01-01

    Energetic electrons of up to tens of MeV are created during explosive phenomena in the solar corona. While many theoretical models consider magnetic reconnection as a possible way of generating energetic electrons, the precise roles of magnetic reconnection during acceleration and heating of electrons still remain unclear. Here we show from 2D particle-in-cell simulations that coalescence of magnetic islands that naturally form as a consequence of tearing mode instability and associated magnetic reconnection leads to efficient energization of electrons. The key process is the secondary magnetic reconnection at the merging points, or the `anti-reconnection', which is, in a sense, driven by the converging outflows from the initial magnetic reconnection regions. By following the trajectories of the most energetic electrons, we found a variety of different acceleration mechanisms but the energization at the anti-reconnection is found to be the most important process. We discuss possible applications to the energe...

  17. COMPASS Accelerator Design Technical Overview

    Energy Technology Data Exchange (ETDEWEB)

    Nanni, Emilio; Dolgashev, Valery; Tantawi, Sami; Neilson, Jeff; /SLAC

    2016-03-14

    This report is a survey of technical options for generating a MeV-class accelerator for space based science applications. The survey was performed focusing on the primary technical requirements of the accelerator in the context of a satellite environment with its unique challenges of limited electrical power (PE), thermal isolation, dimensions, payload requirement and electrical isolation.

  18. Correct and efficient accelerator programming

    OpenAIRE

    Cohen, Albert; Donaldson, Alistair F.; Huisman, Marieke; Katoen, Joost-Pieter

    2013-01-01

    This report documents the program and the outcomes of Dagstuhl Seminar 13142 “Correct and Efficient Accelerator Programming”. The aim of this Dagstuhl seminar was to bring together researchers from various sub-disciplines of computer science to brainstorm and discuss the theoretical foundations, design and implementation of techniques and tools for correct and efficient accelerator programming.

  19. Software for virtual accelerator designing

    International Nuclear Information System (INIS)

    The article discusses appropriate technologies for software implementation of the Virtual Accelerator. The Virtual Accelerator is considered as a set of services and tools enabling transparent execution of computational software for modeling beam dynamics in accelerators on distributed computing resources. Distributed storage and information processing facilities utilized by the Virtual Accelerator make use of the Service-Oriented Architecture (SOA) according to a cloud computing paradigm. Control system tool-kits (such as EPICS, TANGO), computing modules (including high-performance computing), realization of the GUI with existing frameworks and visualization of the data are discussed in the paper. The presented research consists of software analysis for realization of interaction between all levels of the Virtual Accelerator and some samples of middle-ware implementation. A set of the servers and clusters at St.-Petersburg State University form the infrastructure of the computing environment for Virtual Accelerator design. Usage of component-oriented technology for realization of Virtual Accelerator levels interaction is proposed. The article concludes with an overview and substantiation of a choice of technologies that will be used for design and implementation of the Virtual Accelerator. (authors)

  20. Lorentz contraction and accelerated systems

    OpenAIRE

    Tartaglia, Angelo; Ruggiero, Matteo Luca

    2003-01-01

    The paper discusses the problem of the Lorentz contraction in accelerated systems, in the context of the special theory of relativity. Equal proper accelerations along different world lines are considered, showing the differences arising when the world lines correspond to physically connected or disconnected objects. In all cases the special theory of relativity proves to be completely self-consistent

  1. Thomas Edison Accelerated Elementary School.

    Science.gov (United States)

    Levin, Henry M.; Chasin, Gene

    This paper describes early outcomes of a Sacramento, California, elementary school that participated in the Accelerated Schools Project. The school, which serves many minority and poor students, began training for the project in 1992. Accelerated Schools were designed to advance the learning rate of students through a gifted and talented approach,…

  2. New directions in linear accelerators

    International Nuclear Information System (INIS)

    Current work on linear particle accelerators is placed in historical and physics contexts, and applications driving the state of the art are discussed. Future needs and the ways they may force development are outlined in terms of exciting R and D challenges presented to today's accelerator designers. 23 references, 7 figures

  3. Accelerator technology for the mankind

    International Nuclear Information System (INIS)

    Full text: Particle accelerators technology is one of the generic technologies which is locomotive of the development in almost all fields of science and technology. According to the U. S. Department of Energy: Accelerators underpin every activity of the Office of Science and, increasingly, of the entire scientific enterprise. From biology to medicine, from materials to metallurgy, from elementary particles to the cosmos, accelerators provide the microscopic information that forms the basis for scientific understanding and applications. The combination of ground and satellite based observatories and particle accelerators will advance our understanding of our world, our galaxy, our universe, and ourselves. Because of this, accelerator technology should become widespread all over the world. Existing situation shows that a large portion of the world, namely the South and Mid-East, is poor on the accelerator technology. UNESCO has recognized this deficit and started SESAME project in Mid-East, namely Jordan. Turkic Accelerator Complex (TAC) project is more comprehensive and ambitious project, from the point of view of it includes light sources, particle physics experiments and proton and secondary beam applications. At this stage, TAC project includes: Linac-ring type charm factory; Synchrotron light source based on positron ring; Free electron laser based on electron linac; GeV scale proton accelerator; TAC-Test Facility

  4. Analysis of Accelerated Gossip Algorithms

    NARCIS (Netherlands)

    Liu, J.; Anderson, B.D.O.; Cao, M.; Morse, A.S.

    2009-01-01

    This paper investigates accelerated gossip algorithms for distributed computations in networks where shift-registers are utilized at each node. By using tools from matrix analysis, we prove the existence of the desired acceleration and establish the fastest rate of convergence in expectation for two

  5. The entangled accelerating universe

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Diaz, Pedro F. [Colina de los Chopos, Instituto de Fisica Fundamental, Consejo Superior de Investigaciones Cientificas, Serrano 121, 28006 Madrid (Spain); Estacion Ecologica de Biocosmologia, Pedro de Alvarado, 14, 06411-Medellin (Spain)], E-mail: p.gonzalezdiaz@imaff.cfmac.csic.es; Robles-Perez, Salvador [Colina de los Chopos, Instituto de Fisica Fundamental, Consejo Superior de Investigaciones Cientificas, Serrano 121, 28006 Madrid (Spain); Estacion Ecologica de Biocosmologia, Pedro de Alvarado, 14, 06411-Medellin (Spain)

    2009-08-31

    Using the known result that the nucleation of baby universes in correlated pairs is equivalent to spacetime squeezing, we show in this Letter that there exists a T-duality symmetry between two-dimensional warp drives, which are physically expressible as localized de Sitter little universes, and two-dimensional Tolman-Hawking and Gidding-Strominger baby universes respectively correlated in pairs, so that the creation of warp drives is also equivalent to spacetime squeezing. Perhaps more importantly, it has been also seen that the nucleation of warp drives entails a violation of the Bell's inequalities, and hence the phenomena of quantum entanglement, complementarity and wave function collapse. These results are generalized to the case of any dynamically accelerating universe filled with dark or phantom energy whose creation is also physically equivalent to spacetime squeezing and to the violation of the Bell's inequalities, so that the universe we are living in should be governed by essential sharp quantum theory laws and must be a quantum entangled system.

  6. Actinides, accelerators and erosion

    Science.gov (United States)

    Tims, S. G.; Fifield, L. K.

    2012-10-01

    Fallout isotopes can be used as artificial tracers of soil erosion and sediment accumulation. The most commonly used isotope to date has been 137Cs. Concentrations of 137Cs are, however, significantly lower in the Southern Hemisphere, and furthermore have now declined to 35% of original values due to radioactive decay. As a consequence the future utility of 137Cs is limited in Australia, with many erosion applications becoming untenable within the next 20 years, and there is a need to replace it with another tracer. Plutonium could fill this role, and has the advantages that there were six times as many atoms of Pu as of 137Cs in fallout, and any loss to decay has been negligible due to the long half-lives of the plutonium isotopes. Uranium-236 is another long-lived fallout isotope with significant potential for exploitation as a tracer of soil and sediment movement. Uranium is expected to be more mobile in soils than plutonium (or caesium), and hence the 236U/Pu ratio will vary with soil depth, and so could provide an independent measure of the amount of soil loss. In this paper we discuss accelerator based ultra-sensitive measurements of plutonium and 236U isotopes and their advantages over 137Cs as tracers of soil erosion and sediment movement.

  7. EXOTIC MAGNETS FOR ACCELERATORS.

    Energy Technology Data Exchange (ETDEWEB)

    WANDERER, P.

    2005-09-18

    Over the last few years, several novel magnet designs have been introduced to meet the requirements of new, high performance accelerators and beam lines. For example, the FAIR project at GSI requires superconducting magnets ramped at high rates ({approx} 4 T/s) in order to achieve the design intensity. Magnets for the RIA and FAIR projects and for the next generation of LHC interaction regions will need to withstand high doses of radiation. Helical magnets are required to maintain and control the polarization of high energy protons at RHIC. In other cases, novel magnets have been designed in response to limited budgets and space. For example, it is planned to use combined function superconducting magnets for the 50 GeV proton transport line at J-PARC to satisfy both budget and performance requirements. Novel coil winding methods have been developed for short, large aperture magnets such as those used in the insertion region upgrade at BEPC. This paper will highlight the novel features of these exotic magnets.

  8. Is Global Warming Accelerating?

    Science.gov (United States)

    Shukla, J.; Delsole, T. M.; Tippett, M. K.

    2009-12-01

    A global pattern that fluctuates naturally on decadal time scales is identified in climate simulations and observations. This newly discovered component, called the Global Multidecadal Oscillation (GMO), is related to the Atlantic Meridional Oscillation and shown to account for a substantial fraction of decadal fluctuations in the observed global average sea surface temperature. IPCC-class climate models generally underestimate the variance of the GMO, and hence underestimate the decadal fluctuations due to this component of natural variability. Decomposing observed sea surface temperature into a component due to anthropogenic and natural radiative forcing plus the GMO, reveals that most multidecadal fluctuations in the observed global average sea surface temperature can be accounted for by these two components alone. The fact that the GMO varies naturally on multidecadal time scales implies that it can be predicted with some skill on decadal time scales, which provides a scientific rationale for decadal predictions. Furthermore, the GMO is shown to account for about half of the warming in the last 25 years and hence a substantial fraction of the recent acceleration in the rate of increase in global average sea surface temperature. Nevertheless, in terms of the global average “well-observed” sea surface temperature, the GMO can account for only about 0.1° C in transient, decadal-scale fluctuations, not the century-long 1° C warming that has been observed during the twentieth century.

  9. Accelerating quantum universe

    CERN Document Server

    Kuzmichev, V E

    2007-01-01

    The exactly solvable quantum model of the homogeneous, isotropic and closed universe filled with a uniform scalar field and a perfect fluid which defines a reference frame is considered. The equations of the model are reduced to the form which allows a direct comparison between them and the equations of the Einstein classical theory of gravity. It is shown that matter in the universe has a component in a form of a condensate of massive zero-momentum excitation quanta of oscillations of a primordial scalar field which behaves as an antigravitating medium. The theory predicts an accelerating expansion of the universe even if the vacuum energy density vanishes. An antigravitating effect of a condensate has a purely quantum nature. It is ensured by quantum transitions between close states of the universe with different masses of a condensate. It is shown that in a state with large quantum numbers (in semi-classical approximation) the universe has to look effectively like spatially flat with a deceleration paramet...

  10. EXHIBITION: Accelerated Particles

    CERN Document Server

    2004-01-01

    An exhibition of plastic arts and two evenings of performances by sound and visual artists as part of CERN's 50th anniversary celebrations. Fifty candles for CERN, an international laboratory renowned for fundamental research, is a cause for celebration. Since March this year, Geneva and neighbouring parts of France have been the venues for a wealth of small and large-scale events, which will continue until November. Given CERN's location in the commune of Meyrin, the ForuMeyrin is hosting exhibitions of plastic arts and performances entitled: Accelerated Particles. Several works will be exhibited and performed in two 'salons'. Salon des matières: An exhibition of plastic arts From Tues 12 October to Wed 3 November 2004 Tuesdays to Fridays: 16:00 to 19:00 Saturdays: 14:00 to 18:00 Exhibition open late on performance nights, entrance free Salon des particules: Musical and visual performances Tues 12 and Mon 25 October from 20:00 to 23:00 Preview evening for both events: Tues 12 October from 18:...

  11. EXHIBITION: Accelerated Particles

    CERN Multimedia

    2004-01-01

    http://www.cern.ch/cern50/ An exhibition of plastic arts and two evenings of performances by sound and visual artists as part of CERN's fiftieth anniversary celebrations. The fiftieth anniversary of a world famous organization like CERN, an international laboratory specializing in fundamental research, is a cause for celebration. Since March this year, Geneva and neighbouring parts of France have been the venues for a wealth of small and large-scale events, which will continue until November. Given CERN's location in the commune of Meyrin, the ForuMeyrin is hosting two "salons" consisting of an exhibition of plastic arts and evenings of music and visual arts performances with the collective title of "Accelerated Particles". Several works will be exhibited and performed. Salon des matières: An exhibition of plastic arts Until Wednesday 3 November 2004. Tuesdays to Fridays: 4.00 p.m. to 7.00 p.m. Saturdays: 2.00 p.m. to 6.00 p.m. Doors open late on the evening of the performances. Salon des ...

  12. The entangled accelerating universe

    International Nuclear Information System (INIS)

    Using the known result that the nucleation of baby universes in correlated pairs is equivalent to spacetime squeezing, we show in this Letter that there exists a T-duality symmetry between two-dimensional warp drives, which are physically expressible as localized de Sitter little universes, and two-dimensional Tolman-Hawking and Gidding-Strominger baby universes respectively correlated in pairs, so that the creation of warp drives is also equivalent to spacetime squeezing. Perhaps more importantly, it has been also seen that the nucleation of warp drives entails a violation of the Bell's inequalities, and hence the phenomena of quantum entanglement, complementarity and wave function collapse. These results are generalized to the case of any dynamically accelerating universe filled with dark or phantom energy whose creation is also physically equivalent to spacetime squeezing and to the violation of the Bell's inequalities, so that the universe we are living in should be governed by essential sharp quantum theory laws and must be a quantum entangled system.

  13. LHC Dipoles Accelerate

    CERN Multimedia

    2001-01-01

    Andrezej Siemko (left), Peter Sievers (centre), and Lucio Rossi (right), have the exciting challenge of preparing and testing 2000 magnets for the LHC. The LHC is going to require a lot of powerful magnets by the time it begins operation in 2006. More specifically, it is going to need 130 special magnets, 400 quadrupoles, and a whopping 1250 dipoles! Preparing and testing these magnets for the conditions they will encounter in the LHC is not an easy task. But evaluation of the most recently received magnet, from the German company Noell, is showing that while the monumental task of receiving and testing nearly 2000 magnets is going to be exhausting, the goals are definitely attainable. At the moment and over the next year, pre-series magnets (the magnets that CERN uses to fine tune performance) are arriving slowly (90 in total will arrive), but by 2003 the rate of series magnet arrival will accelerate to 9 per week, that's over 450 in a single year! And working with these magnets when they arrive is tough. ...

  14. SPS RF Accelerating Cavity

    CERN Multimedia

    1979-01-01

    This picture shows one of the 2 new cavities installed in 1978-1979. The main RF-system of the SPS comprises four cavities: two of 20 m length and two of 16.5 m length. They are all installed in one long straight section (LSS 3). These cavities are of the travelling-wave type operating at a centre frequency of 200.2 MHz. They are wideband, filling time about 700 ns and untuned. The power amplifiers, using tetrodes are installed in a surface building 200 m from the cavities. Initially only two cavities were installed, a third cavity was installed in 1978 and a forth one in 1979. The number of power amplifiers was also increased: to the first 2 MW plant a second 2 MW plant was added and by end 1979 there were 8 500 kW units combined in pairs to feed each of the 4 cavities with up to about 1 MW RF power, resulting in a total accelerating voltage of about 8 MV. See also 7412016X, 7412017X, 7411048X

  15. Actinides, accelerators and erosion

    Directory of Open Access Journals (Sweden)

    Fifield L.K.

    2012-10-01

    Full Text Available Fallout isotopes can be used as artificial tracers of soil erosion and sediment accumulation. The most commonly used isotope to date has been 137Cs. Concentrations of 137Cs are, however, significantly lower in the Southern Hemisphere, and furthermore have now declined to 35% of original values due to radioactive decay. As a consequence the future utility of 137Cs is limited in Australia, with many erosion applications becoming untenable within the next 20 years, and there is a need to replace it with another tracer. Plutonium could fill this role, and has the advantages that there were six times as many atoms of Pu as of 137Cs in fallout, and any loss to decay has been negligible due to the long half-lives of the plutonium isotopes. Uranium-236 is another long-lived fallout isotope with significant potential for exploitation as a tracer of soil and sediment movement. Uranium is expected to be more mobile in soils than plutonium (or caesium, and hence the 236U/Pu ratio will vary with soil depth, and so could provide an independent measure of the amount of soil loss. In this paper we discuss accelerator based ultra-sensitive measurements of plutonium and 236U isotopes and their advantages over 137Cs as tracers of soil erosion and sediment movement.

  16. Heavy ion accelerators at GSI

    International Nuclear Information System (INIS)

    The status of the Unilac heavy ion linear accelerator at GSI, Darmstadt is given. A schematic overall plan view of the Unilac is shown and its systems are described. List of isotopes and intensities accelerated at the Unilac is presented. The experimental possibilities at GSI should be considerably extended by a heavy ion synchrotron (SIS 18) in combination with an experimental storage ring (ESR). A prototype of the rf-accelerating system of the synchrotron has been built and tested. Prototypes for the quadrupole and dipole magnets for the ring are being constructed. The SIS 18 is desigmed for a maximum magnetic rigidity of 18Tm so that neon can be accelerated to 2 GeV/W and uranium to 1 GeV/u. The design allows also the acceleration of protons up to 4.5 GeV. The ESR permits to storage fully stripped uranium ions up to an energy of approximately R50 MeV/u

  17. Industrial accelerators and their applications

    CERN Document Server

    Hamm, Marianne E

    2012-01-01

    This unique new book is a comprehensive review of the many current industrial applications of particle accelerators, written by experts in each of these fields. Readers will gain a broad understanding of the principles of these applications, the extent to which they are employed, and the accelerator technology utilized. The book also serves as a thorough introduction to these fields for non-experts and laymen. Due to the increased interest in industrial applications, there is a growing interest among accelerator physicists and many other scientists worldwide in understanding how accelerators are used in various applications. The government agencies that fund scientific research with accelerators are also seeking more information on the many commercial applications that have been or can be developed with the technology developments they are funding. Many industries are also doing more research on how they can improve their products or processes using particle beams.

  18. Maximal acceleration and radiative processes

    CERN Document Server

    Papini, Giorgio

    2015-01-01

    We derive the radiation characteristics of an accelerated, charged particle in a model due to Caianiello in which the proper acceleration of a particle of mass $m$ has the upper limit $\\mathcal{A}_m=2mc^3/\\hbar$. We find two power laws, one applicable to lower accelerations, the other more suitable for accelerations closer to $\\mathcal{A}_m$ and to the related physical singularity in the Ricci scalar. Geometrical constraints and power spectra are also discussed. By comparing the power laws due to the maximal acceleration with that for particles in gravitational fields, we find that the model of Caianiello allows, in principle, the use of charged particles as tools to distinguish inertial from gravitational fields locally.

  19. Maximal acceleration and radiative processes

    Science.gov (United States)

    Papini, Giorgio

    2015-08-01

    We derive the radiation characteristics of an accelerated, charged particle in a model due to Caianiello in which the proper acceleration of a particle of mass m has the upper limit 𝒜m = 2mc3/ℏ. We find two power laws, one applicable to lower accelerations, the other more suitable for accelerations closer to 𝒜m and to the related physical singularity in the Ricci scalar. Geometrical constraints and power spectra are also discussed. By comparing the power laws due to the maximal acceleration (MA) with that for particles in gravitational fields, we find that the model of Caianiello allows, in principle, the use of charged particles as tools to distinguish inertial from gravitational fields locally.

  20. The ISAC post-accelerator

    Science.gov (United States)

    Laxdal, R. E.; Marchetto, M.

    2014-01-01

    The acceleration chain of the ISAC facility boosts the energy of both radioactive and stable light and heavy ions for beam delivery to both a medium energy area in ISAC-I and a high energy area in ISAC-II. The post-accelerator comprises a 35.4 MHz RFQ to accelerate beams of A/q ≤ 30 from 2 keV/u to 150 keV/u and a post stripper, 106.1 MHz variable energy drift tube linac (DTL) to accelerate ions of A/q ≤ 6 to a final energy between 0.15 MeV/u to 1.5 MeV/u. A 40 MV superconducting linac further accelerates beam from 1.5 MeV/u to energies above the Coulomb barrier. All linacs operate cw to preserve beam intensity.

  1. Ion sources for electrostatic accelerators

    International Nuclear Information System (INIS)

    Maybe the most important part of an electrostatic accelerator system, and also often the most tricky part is the ion source. There has been a rapid growth in activity in ion-source research and development during the last two to three decades. Some of these developments have also been of benefit to electrostatic accelerator users. In this report some of the different types of ion sources used in electrostatic accelerators are described. The list is not complete but more an overview of some of the more commonly used sources. The description is divided into two groups; positive ion sources for single stage electrostatic accelerators and negative ion sources for two stages (i.e. tandem) accelerators

  2. Velocity bunching in travelling wave accelerator with low acceleration gradient

    CERN Document Server

    Huang, Rui-Xuan; Li, Wei-Wei; Jia, Qi-Ka

    2013-01-01

    We present the analytical and simulated results concerning the influences of the acceleration gradient in the velocity bunching process, which is a bunch compression scheme that uses a traveling wave accelerating structure as a compressor. Our study shows that the bunch compression application with low acceleration gradient is more tolerant to phase jitter and more successful to obtain compressed electron beam with symmetrical longitudinal distribution and low energy spread. We also present a transverse emittance compensation scheme to compensate the emittance growth caused by the increasing of the space charge force in the compressing process that is easy to be adjusted for different compressing factors.

  3. Quantitative Accelerated Life Testing of MEMS Accelerometers

    Directory of Open Access Journals (Sweden)

    Jean-Paul Collette

    2007-11-01

    Full Text Available Quantitative Accelerated Life Testing (QALT is a solution for assessing thereliability of Micro Electro Mechanical Systems (MEMS. A procedure for QALT is shownin this paper and an attempt to assess the reliability level for a batch of MEMSaccelerometers is reported. The testing plan is application-driven and contains combinedtests: thermal (high temperature and mechanical stress. Two variants of mechanical stressare used: vibration (at a fixed frequency and tilting. Original equipment for testing at tiltingand high temperature is used. Tilting is appropriate as application-driven stress, because thetilt movement is a natural environment for devices used for automotive and aerospaceapplications. Also, tilting is used by MEMS accelerometers for anti-theft systems. The testresults demonstrated the excellent reliability of the studied devices, the failure rate in the“worst case” being smaller than 10-7h-1.

  4. Accelerated coffee pulp composting.

    Science.gov (United States)

    Sánchez, G; Olguín, E J; Mercado, G

    1999-02-01

    The effect of two abundant, easily available and very low-cost agro-industrial organic residues, i.e., filter cake from the sugar industry and poultry litter, on the composting stabilization time of coffee pulp and on the quality of the produced compost, was evaluated. Piles of one cubic meter were built and monitored within the facilities of a coffee processing plant in the Coatepec region of the State of Veracruz, Mexico. Manual aeration was carried out once a week. A longer thermophilic period (28 days) and a much lower C/N ratio (in the range of 6.9-9.1) were observed in the piles containing the amendments, as compared to the control pile containing only coffee pulp (14 days and a C/N ratio of 14.4, respectively). The maximum assimilation rate of the reducing sugars was 1.6 g kg-1 d-1 (from 7.5 to 5.3%) during the first two weeks when accelerators were present in the proportion of 20% filter cake plus 20% poultry litter, while they accumulated at a rate of 1.2 g kg-1 d-1 (from 7.4 to 9.13%) during the same period in the control pile. The best combination of amendments was 30% filter cake with 20% poultry litter, resulting in a final nitrogen content as high as 4.81%. The second best combination was 20% filter cake with 10% poultry litter, resulting in a compost which also contained a high level of total nitrogen (4.54%). It was concluded that the use of these two residues enhanced the composting process of coffee pulp, promoting a shorter stabilization period and yielding a higher quality of compost.

  5. Operation of the accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Pardo, R.C.; Batzka, B.; Billquist, P.J. [and others

    1995-08-01

    Fiscal Year 1994 was the first year of seven-day operation since ATLAS became a national user facility in 1985. ATLAS made the most of the opportunity this year by providing 5200 hours of beam on-target to the research program. A record number of 60 experiments were completed and the {open_quotes}facility reliability{close_quotes} remained near the 90% level. Seven-day operation was made possible with the addition to the staff of two operator positions providing single-operator coverage during the weekend period. The normally scheduled coverage was augmented by an on-call list of system experts who respond to emergencies with phone-in advice and return to the Laboratory when necessary. This staffing approach continues but we rearranged our staffing patterns so that we now have one cryogenics engineer working a shift pattern which includes 8-hour daily coverage during the weekend. ATLAS provided a beam mix to users consisting of 26 different isotopic species, 23% of which were for A>100 in FY 1994. Approximately 60% of the beam time was provided by the Positive Ion Injector, slightly less than the usage rate of FY 1993. Experiments using uranium or lead beams accounted for 16.4% of the total beam time. The ECR ion source and high-voltage platform functioned well throughout the year. A new technique for solid material production in the source was developed which uses a sputtering process wherein the sample of material placed near the plasma chamber wall is biased negatively. Plasma ions are accelerated into the sample and material is sputtered from the surface into the plasma. This technique is now used routinely for many elements. Runs of calcium, germanium, nickel, lead, tellurium, and uranium were carried out with this technique.

  6. Accelerating DSMC data extraction.

    Energy Technology Data Exchange (ETDEWEB)

    Gallis, Michail A.; Piekos, Edward Stanley

    2006-10-01

    In many direct simulation Monte Carlo (DSMC) simulations, the majority of computation time is consumed after the flowfield reaches a steady state. This situation occurs when the desired output quantities are small compared to the background fluctuations. For example, gas flows in many microelectromechanical systems (MEMS) have mean speeds more than two orders of magnitude smaller than the thermal speeds of the molecules themselves. The current solution to this problem is to collect sufficient samples to achieve the desired resolution. This can be an arduous process because the error is inversely proportional to the square root of the number of samples so we must, for example, quadruple the samples to cut the error in half. This work is intended to improve this situation by employing more advanced techniques, from fields other than solely statistics, for determining the output quantities. Our strategy centers on exploiting information neglected by current techniques, which collect moments in each cell without regard to one another, values in neighboring cells, nor their evolution in time. Unlike many previous acceleration techniques that modify the method itself, the techniques examined in this work strictly post-process so they may be applied to any DSMC code without affecting its fidelity or generality. Many potential methods are drawn from successful applications in a diverse range of areas, from ultrasound imaging to financial market analysis. The most promising methods exploit relationships between variables in space, which always exist in DSMC due to the absence of shocks. Disparate techniques were shown to produce similar error reductions, suggesting that the results shown in this report may be typical of what is possible using these methods. Sample count reduction factors of approximately three to five were found to be typical, although factors exceeding ten were shown on some variables under some techniques.

  7. "small ACCELERATORS" 24 May - 2 June 2005

    CERN Multimedia

    2005-01-01

    CERN Accelerator School and Kernfysisch Versneller Instituut (KVI) Groningen, the Netherlands announce a course on "Small Accelerators", Hotel Golden Tulip Drenthe, Zeegse, the Netherlands, 24 May - 2 June 2005. This specialised course is dedicated to the physics and the main applications of small accelerators. The course will review the different accelerator types as well as their specificities in terms of accelerator physics.

  8. Application of electron accelerator worldwide

    Energy Technology Data Exchange (ETDEWEB)

    Machi, Sueo [Japan Atomic Industrial Forum, Inc., Tokyo (Japan)

    2003-02-01

    Electron accelerator is an important radiation source for radiation technology, which covers broad fields such as industry, health care, food and environmental protection. There are about 1,000 electron accelerators for radiation processing worldwide. Electron accelerator has advantage over Co-60 irradiator in term of high dose rate and power, assurance of safety, and higher economic performance at larger volume of irradiation. Accelerator generating higher energy in the range of 10 MeV and high power electron beam is now commercially available. There is a trend to use high-energy electron accelerator replacing Co-60 in case of large through-put of medical products. Irradiated foods, in particular species, are on the commercial market in 35 countries. Electron accelerator is used efficiently and economically for production of new or modified polymeric materials through radiation-induced cross-linking, grafting and polymerization reaction. Another important application of electron beam is the curing of surface coatings in the manufacture of products. Electron accelerators of large capacity are used for cleaning exhaust gases in industrial scale. Economic feasibility studies of this electron beam process have shown that this technology is more cost effective than the conventional process. It should be noted that the conventional limestone process produce gypsum as a by-product, which cannot be used in some countries. By contrast, the by-product of the electron beam process is a valuable fertilizer. (Y. Tanaka)

  9. Application of electron accelerator worldwide

    International Nuclear Information System (INIS)

    Electron accelerator is an important radiation source for radiation technology, which covers broad fields such as industry, health care, food and environmental protection. There are about 1,000 electron accelerators for radiation processing worldwide. Electron accelerator has advantage over Co-60 irradiator in term of high dose rate and power, assurance of safety, and higher economic performance at larger volume of irradiation. Accelerator generating higher energy in the range of 10 MeV and high power electron beam is now commercially available. There is a trend to use high-energy electron accelerator replacing Co-60 in case of large through-put of medical products. Irradiated foods, in particular species, are on the commercial market in 35 countries. Electron accelerator is used efficiently and economically for production of new or modified polymeric materials through radiation-induced cross-linking, grafting and polymerization reaction. Another important application of electron beam is the curing of surface coatings in the manufacture of products. Electron accelerators of large capacity are used for cleaning exhaust gases in industrial scale. Economic feasibility studies of this electron beam process have shown that this technology is more cost effective than the conventional process. It should be noted that the conventional limestone process produce gypsum as a by-product, which cannot be used in some countries. By contrast, the by-product of the electron beam process is a valuable fertilizer. (Y. Tanaka)

  10. 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

  11. CAS CERN Accelerator School second advanced accelerator physics course

    International Nuclear Information System (INIS)

    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.)

  12. Determination of beam characteristic parameters for a linear accelerator

    International Nuclear Information System (INIS)

    A mechanism to determine electron beam characteristic parameters of a linear accelerator was constructed. The mechanism consists in an electro-calorimeter and an accurate optical densitometer. The following parameters: mean power, mean current, mean energy/particle, pulse Width, pulse amplitude dispersion, and pulse frequency, operating the 2 MeV linear accelerator of CBPF (Brazilian Center pf Physics Researches). The optical isodensity curves of irradiated glass lamellae were obtained, providing information about focus degradation penetration direction in material and the reach of particle. The point to point dose distribution in the material from optical density curves were obtained, using a semi empirical and approached model. (M.C.K.)

  13. Nonlinear theory of diffusive acceleration of particles by shock waves

    International Nuclear Information System (INIS)

    Among the various acceleration mechanisms which have been suggested as responsible for the nonthermal particle spectra and associated radiation observed in many astrophysical and space physics environments, diffusive shock acceleration appears to be the most successful. We review the current theoretical understanding of this process, from the basic ideas of how a shock energizes a few reactionless particles to the advanced nonlinear approaches treating the shock and accelerated particles as a symbiotic self-organizing system. By means of direct solution of the nonlinear problem we set the limit to the test-particle approximation and demonstrate the fundamental role of nonlinearity in shocks of astrophysical size and lifetime. We study the bifurcation of this system, proceeding from the hydrodynamic to kinetic description under a realistic condition of Bohm diffusivity. We emphasize the importance of collective plasma phenomena for the global flow structure and acceleration efficiency by considering the injection process, an initial stage of acceleration and, the related aspects of the physics of collisionless shocks. We calculate the injection rate for different shock parameters and different species. This, together with differential acceleration resulting from nonlinear large-scale modification, determines the chemical composition of accelerated particles. The review concentrates on theoretical and analytical aspects but our strategic goal is to link the fundamental theoretical ideas with the rapidly growing wealth of observational data. (author)

  14. Effect of fringe divergence in fluid acceleration measurement using LDA

    Energy Technology Data Exchange (ETDEWEB)

    Chun, Se Jong; Sung, Hyung Jin [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of); Nobach, Holger; Tropea, Cam [Technische Universitat Darmstadt, Darmstadt (Germany)

    2004-07-01

    The laser Doppler technique is well-established as a velocity measurement technique of high precision for flow velocity. Recently, the laser Doppler technique has also been used to measure acceleration of fluid particles. Acceleration is interesting from a fluid mechanics point of view, since the Navier Stokes equations, specifically the left-hand-side, are formulated in terms of fluid acceleration. Further, there are several avenues to estimating the dissipation rate using the acceleration. However such measurements place additional demands on the design of the optical system; in particular fringe non-uniformity must be held below about 0.0001 to avoid systematic errors. Relations expressing fringe divergence as a function of the optical parameters of the system have been given in the literature; however, direct use of these formulae to minimize fringe divergence lead either to very large measurement volumes or to extremely high intersection angles. This dilemma can be resolved by using an off-axis receiving arrangement, in which the measurement volume is truncated by a pinhole in front of the detection plane. In the present study an optical design study is performed for optimizing laser Doppler systems for fluid acceleration measurements. This is followed by laboratory validation using a round free jet and a stagnation flow, two flows in which either fluid acceleration has been previously measured or in which the acceleration is known analytically. A 90 degree off-axis receiving angle is used with a pinhole or a slit.

  15. The Radiological Research Accelerator Facility

    International Nuclear Information System (INIS)

    The Radiological Research Accelerator Facility (RARAF) is based on a 4-MV Van de Graaff accelerator, which is used to generate a variety of well-characterized radiation beams for research in radiobiology, radiological physics, and radiation chemistry. It is part of the Center for Radiological Research (CRR) -- formerly the Radiological Research Laboratory (RRL) -- of Columbia University, and its operation is supported as a National Facility by the US Department of Energy (DOE). Fifteen different experiments were run during these 12 months, approximately the same as the previous two years. Brief summaries of each experiment are included. Accelerator usage is summarized and development activities are discussed. 7 refs., 4 tabs

  16. Stochastic modeling of Lagrangian accelerations

    Science.gov (United States)

    Reynolds, Andy

    2002-11-01

    It is shown how Sawford's second-order Lagrangian stochastic model (Phys. Fluids A 3, 1577-1586, 1991) for fluid-particle accelerations can be combined with a model for the evolution of the dissipation rate (Pope and Chen, Phys. Fluids A 2, 1437-1449, 1990) to produce a Lagrangian stochastic model that is consistent with both the measured distribution of Lagrangian accelerations (La Porta et al., Nature 409, 1017-1019, 2001) and Kolmogorov's similarity theory. The later condition is found not to be satisfied when a constant dissipation rate is employed and consistency with prescribed acceleration statistics is enforced through fulfilment of a well-mixed condition.

  17. Particle acceleration in modified shocks

    International Nuclear Information System (INIS)

    Efficient particle acceleration in shocks must modify the shock structure with consequent changes in the particle acceleration. This effect is studied and analytic solutions are found describing the diffusive acceleration of particles with momentum independent diffusion coefficients in hyperbolic tangent type velocity transitions. If the input particle spectrum is a delta function, the shock smoothing replaces the truncated power-law downstream particle spectrum by a more complicated form, but one which has a power-law tail at high momenta. For a cold plasma this solution can be made completely self-consistent. Some problems associated with momentum dependent diffusion coefficients are discussed. (author)

  18. Electromagnetic acceleration of permanent magnets

    CERN Document Server

    Dolya, S N

    2015-01-01

    We consider the acceleration of the permanent magnets, consisting of neodymium iron boron by means of the running magnetic field gradient. It is shown that the specific magnetic moment per nucleon in neodymium iron boron is determined by the remained magnetization of the substance. The maximum accessable gradient of the magnetic field accelerating the permanent magnets is determined by the coercive force thirty kilogauss. For the neodymium iron boron magnets this gradient is equal to twenty kilogauss divided by one centimeter. The finite velocity of the magnets six kilometers per second, the length of acceleration is six hundred thirty-seven meters.

  19. New type of collective accelerator

    International Nuclear Information System (INIS)

    A collective accelerator based on magnetically confined plasma rings is described. Typical rings which have been produced and which have 10 kJ magnetic energy and 0.1 to 10 coulombs of nuclei are predicted to be accelerated magnetically to 10 MJ or higher in acceleration lengths of 100 m if the final power delivered to the ring is 1012 W. Applications are discussed of current drive in Tokamak fusion reactions, fueling and heating magnetic fusion reactors, transuranic element synthesis, and, for focused rings, a high energy density driver for inertial confinement fusion

  20. Ion acceleration with ultra intense and ultra short laser pulses

    International Nuclear Information System (INIS)

    Accelerating ions/protons can be done using short laser pulse (few femto-seconds) focused on few micrometers area on solid target (carbon, aluminum, plastic...). The electromagnetic field intensity reached on target (≥1018 W.cm-2) allows us to turn the solid into a hot dense plasma. The dynamic motion of the electrons is responsible for the creation of intense static electric field at the plasma boundaries. These electric fields accelerate organic pollutants (including protons) located at the boundaries. This acceleration mechanism known as the Target Normal Sheath Acceleration (TNSA) has been the topic of the research presented in this thesis.The goal of this work has been to study the acceleration mechanism and to increase the maximal ion energy achievable. Indeed, societal application such as proton therapy requires proton energy up to few hundreds of MeV. To proceed, we have studied different target configurations allowing us to increase the laser plasma coupling and to transfer as much energy as possible to ions (target with microspheres deposit, foam target, grating). Different experiments have also dealt with generating a pre-plasma on the target surface thanks to a pre-pulse. On the application side, fluorescent material such as CdWO4 has been studied under high flux rate of protons. These high flux rates have been, up to now, beyond the conventional accelerators capabilities. (author)

  1. Negative ion sources for tandem accelerator

    International Nuclear Information System (INIS)

    Four kinds of negative ion sources (direct extraction Duoplasmatron ion source, radial extraction Penniing ion source, lithium charge exchange ion source and Middleton-type sputter ion source) have been installed in the JAERI tandem accelerator. The ion sources can generate many negative ions ranging from Hydrogen to Uranium with the exception of Ne, Ar, Kr, Xe and Rn. Discussions presented in this report include mechanisms of negative ion formation, electron affinity and stability of negative ions, performance of the ion sources and materials used for negative ion production. Finally, the author will discuss difficult problems to be overcome in order to get any negative ion sufficiently. (author)

  2. Parametric injection for monoenergetic electron acceleration

    Energy Technology Data Exchange (ETDEWEB)

    Oguchi, A; Takano, K; Hotta, E; Nemoto, K [Department of Energy Sciences Tokyo Institute of Technology 4259 Nagatsuta-cho Midori-ku Yokohama 226-8502 Japan (Japan); Zhidkov, A [Central Research Instistute of Electric Power Industry 2-6-1 Nagasaka Yokosuka Kanagawa 240-0196 Japan (Japan); Nakajima, K [High Energy Accelerator Research Organization, KEK 1-1 Oho Tsukuba Ibaraki 305-0801 Japan (Japan)], E-mail: blue-ayu@plasma.es.titech.ac.jp

    2008-05-01

    Electrons are accelerated in the laser wakefield (LWFA). This mechanism has been studied by 2D or 3D Particle In Cell simulation. However, how the electrons are injected in the wakefield is not understood. In this paper, we consider about the process of self -injection and propose new scheme. When plasma electron density modulates, parametric resonance of electron momentum is induced. The parametric resonance depends on laser waist modulation. We carried out 2D PIC simulation with the initial condition decided from resonance condition. Moreover, we analyze experimental result that generated 200-250 MeV monoenergetic electron beam with 400TW intense laser in CAEP in China.

  3. Cosmic ray acceleration search in Supernova Remnants

    Energy Technology Data Exchange (ETDEWEB)

    Giordano, Francesco; Di Venere, Leonardo [Dipartimento di Fisica M. Merlin dell' Università e del Politecnico di Bari, I-70126 Bari (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Bari, I-70126 Bari (Italy)

    2014-11-15

    Galactic Supernova Remnants (SNRs) are among the best candidates as source of cosmic rays due to energetics, observed rate of explosion and as possible sites where the Fermi mechanisms naturally plays a key role. Evidence of hadronic acceleration processes taking place in SNRs are being collected with the Fermi-LAT, whose sensitivity in the range 100MeV–100GeV is crucial for disentangling possible hadronic contribution from inverse Compton or bremsstrahlung leptonic component. A survey of the detected SNRs will be given, focusing the attention on the role of the environment and the evolution stage of the SNR in the interpretation of the observed γ-ray spectra.

  4. Accelerator Technology: Magnets, Normal and Superconducting

    CERN Document Server

    Bottura, L

    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 '8.1 Magnets, Normal and Superconducting' of the Chapter '8 Accelerator Technology' with the content: 8.1 Magnets, Normal and Superconducting 8.1.1 Introduction 8.1.2 Normal Conducting Magnets 8.1.2.1 Magnetic Design 8.1.2.2 Coils 8.1.2.3 Yoke 8.1.2.4 Costs 8.1.2.5 Undulators, Wigglers, Permanent Magnets 8.1.2.6 Solenoids 8.1.3 Superconducting Magnets 8.1.3.1 Superconducting Materials 8.1.3.2 Superconducting Cables 8.1.3.3 Stability and Margins, Quench and Protection 8.1.3.4 Magnetization, Coupling and AC Loss 8.1.3.5 Magnetic Design of Superconducting Accelerator Magnets 8.1.3.6 Current Leads 8.1.3.7 Mechanics, Insulation, Cooling and Manufacturing Aspects

  5. Plasma acceleration in the Martian magnetotail

    Science.gov (United States)

    Esteban Hernandez, Rosa; Modolo, Ronan; Leblanc, François; Chaufray, Jean-Yves; Curry, Shannon M.; Steckiewicz, Morgane; Connerney, John E. P.; McFadden, James P.; Jakosky, Bruce M.; Brain, David A.; DiBraccio, Gina A.; Romanelli, Norberto; Halekas, Jasper S.; Mitchell, David L.

    2016-04-01

    Since November 2014, the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft has been collecting data from Mars's upper atmosphere and induced magnetosphere (Jakosky et al., 2015). Evidences of escaping planetary ions have been reported from earlier missions as Mars-Express (Barabash et al., 2007) and more recently from MAVEN (e.g. Dong et al., 2015, Brain et al., 2015). Our goal is to determine the acceleration mechanism responsible for the energization of planetary ions in the Martian plasma sheet. MAVEN has a full plasma package with a magnetometer and plasma particles instruments, which allow to address the question of plasma particle acceleration. According to Dubinin et al. (2011), the j x B force due to magnetic shear stresses of the draped field lines is expected to play a major role in such energization process. On MAVEN data, we have first identified and characterized current sheet crossings taking place in Mars' magnetotail and then tested the Walén relation to infer the significance of the j x B force in the particle's energization. To characterize the plasma sheet crossing we have worked with MAVEN magnetometer (MAG, Connerney et al., SSR, 2015) and mass spectrometer (STATIC, McFadden et al., SSR, 2015) data, focusing on a particular event. We have performed a minimum variance analysis, on the magnetic field observations which allows to characterize the current sheet. We present results of the Walén test and our conclusions on planetary plasma acceleration in the plasma sheet region.

  6. Accelerated tests of coil coatings

    Directory of Open Access Journals (Sweden)

    Rosales, B. M.

    2003-12-01

    Full Text Available Accelerated laboratory tests on 12 materials in study in the Subgroup 6 of the PATINA Network (CYTED, are discussed for different exposition periods in salt spray, SO2 and Prohesion chambers. International standards used to evaluate failures caused by the different aggressive agents of these laboratory tests are the same as those applied for outdoor expositions. The results exposed contribute to a better understanding of the mechanisms occurred in the diverse natural environments, being mentioned the main analogies and differences respect to factors affecting natural tests. They also allowed to evidence the advantages and limitations in the application of these tests during several days, as compared to the years required to attain similar failure magnitudes through outdoor tests.

    En este trabajo se discuten los ensayos de laboratorio acelerados, realizados sobre 12 materiales de estudio en el Subgrupo 6 de la Red PATINA (CYTED, a diferentes periodos de exposición en cámaras de niebla salina, SO2 y Prohesion. Se utilizaron las normas internacionales para evaluar los fallos causados por los diferentes agentes agresivos de estos ensayos de laboratorio, las cuales se aplican también para los ensayos de exposición a la intemperie. Los resultados expuestos contribuyen a una mejor comprensión de los mecanismos ocurridos en los diversos ambientes naturales, mencionándose las principales analogías y diferencias respecto de los factores que afectan los ensayos naturales. También permitieron evidenciar las ventajas y limitaciones en la aplicación de estos ensayos durante varios días, en comparación con los años requeridos para alcanzar magnitudes de fallos similares por medio de ensayos a intemperie.

  7. Argonne lectures on particles accelerator magnets

    Energy Technology Data Exchange (ETDEWEB)

    Devred, A

    1999-09-01

    The quest for elementary particles has promoted the development of particle accelerators producing beams of increasingly higher energies. In a synchrotron, the particle energy is directly proportional to the product of the machine's radius times the bending magnets' field strength. Present proton experiments at the TeV scale require facilities with circumferences ranging from a few to tens of kilometers and relying on a large number (several hundred to several thousand) high field dipole magnets and high field gradient quadrupole magnets. These electro-magnets use high-current-density, low-critical-temperature superconducting cables and are cooled down at liquid helium temperature. They are among the most costly and the most challenging components of the machine. After explaining what are the various types of accelerator magnets and why they are needed (lecture 1), we briefly recall the origins of superconductivity and we review the parameters of existing superconducting particle accelerators (lecture 2). Then, we review the superconducting materials that are available at industrial scale (chiefly, NbTi and Nb{sub 3}Sn) and we explain in details the manufacturing of NbTi wires and cables (lecture 3). We also present the difficulties of processing and insulating Nb{sub 3}Sn conductors, which so far have limited the use of this material in spite of its superior performances. We continue by discussing the two dimensional current distributions which are the most appropriate for generating pure dipole and quadrupole fields and we explain how these ideal distributions can be approximated by so called cos{theta} and cos 2{theta} coil designs (lecture 4). We also present a few alternative designs which are being investigated and we describe the difficulties of realizing coil ends. Next, we present the mechanical design concepts that are used in existing accelerator magnets (lecture 5) and we describe how the magnets are assembled (lecture 6). Some of the toughest

  8. Argonne lectures on particles accelerator magnets

    International Nuclear Information System (INIS)

    The quest for elementary particles has promoted the development of particle accelerators producing beams of increasingly higher energies. In a synchrotron, the particle energy is directly proportional to the product of the machine's radius times the bending magnets' field strength. Present proton experiments at the TeV scale require facilities with circumferences ranging from a few to tens of kilometers and relying on a large number (several hundred to several thousand) high field dipole magnets and high field gradient quadrupole magnets. These electro-magnets use high-current-density, low-critical-temperature superconducting cables and are cooled down at liquid helium temperature. They are among the most costly and the most challenging components of the machine. After explaining what are the various types of accelerator magnets and why they are needed (lecture 1), we briefly recall the origins of superconductivity and we review the parameters of existing superconducting particle accelerators (lecture 2). Then, we review the superconducting materials that are available at industrial scale (chiefly, NbTi and Nb3Sn) and we explain in details the manufacturing of NbTi wires and cables (lecture 3). We also present the difficulties of processing and insulating Nb3Sn conductors, which so far have limited the use of this material in spite of its superior performances. We continue by discussing the two dimensional current distributions which are the most appropriate for generating pure dipole and quadrupole fields and we explain how these ideal distributions can be approximated by so called cosθ and cos 2θ coil designs (lecture 4). We also present a few alternative designs which are being investigated and we describe the difficulties of realizing coil ends. Next, we present the mechanical design concepts that are used in existing accelerator magnets (lecture 5) and we describe how the magnets are assembled (lecture 6). Some of the toughest requirements on the performance

  9. DYNAMIC MODELING OF METAMORPHIC MECHANISM

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The concept of metamorphic mechanism is put forward according to the change of configurations from one state to another. Different configurations of metamorphic mechanism are described through the method of Huston lower body arrays. Kinematics analyses for metamorphic mechanism with generalized topological structure, including the velocity, angular velocity, acceleration and angular acceleration, are given. Dynamic equations for an arbitrary configuration, including close-loop constraints, are formed by using Kane's equations. For an arbitrary metamorphic mechanism, the transformation matrix of generalized speeds between configuration (*)and(*)+1 is obtained for the first time. Furthermore, configuration-complete dynamic modeling of metamorphic mechanism including all configurations is completely established.

  10. The Effect of Novel Binary Accelerator System on Properties of Vulcanized Natural Rubber

    Directory of Open Access Journals (Sweden)

    Moez Kamoun

    2009-01-01

    Full Text Available The mechanical properties, curing characteristics, and swelling behaviour of vulcanized natural rubber with a novel binary accelerator system are investigated. Results indicate that the mechanical properties were improved. Crosslinking density of vulcanized natural rubber was measured by equilibrium swelling method. As a result, the new binary accelerator was found to be able to improve both cure rate and crosslinking density. Using the numerical analysis of test interaction between binary accelerator and operational modelling of vulcanization-factors experiments, it can be concluded that the interaction (Cystine, N-cyclohexyl-2-benzothiazyl sulfenamide was significant and the optimum value of binary accelerator was suggested, respectively, at levels 0 and +1.

  11. Probing Acceleration and Turbulence at Relativistic Shocks in Blazar Jets

    CERN Document Server

    Baring, Matthew G; Summerlin, Errol J

    2016-01-01

    Diffusive shock acceleration (DSA) at relativistic shocks is widely thought to be an important acceleration mechanism in various astrophysical jet sources, including radio-loud active galactic nuclei such as blazars. Such acceleration can produce the non-thermal particles that emit the broadband continuum radiation that is detected from extragalactic jets. An important recent development for blazar science is the ability of Fermi-LAT spectroscopy to pin down the shape of the distribution of the underlying non-thermal particle population. This paper highlights how multi-wavelength spectra spanning optical to X-ray to gamma-ray bands can be used to probe diffusive acceleration in relativistic, oblique, magnetohydrodynamic (MHD) shocks in blazar jets. Diagnostics on the MHD turbulence near such shocks are obtained using thermal and non-thermal particle distributions resulting from detailed Monte Carlo simulations of DSA. These probes are afforded by the characteristic property that the synchrotron $\

  12. Combined Particle Acceleration in Solar Flares and Associated CME Shocks

    Science.gov (United States)

    Petrosian, Vahe

    2016-07-01

    I will review some observations of the characteristics of accelerated electrons seen near Earth (as SEPs) and those producing flare radiation in the low corona and chromosphere. The similarities and differences between the numbers, spectral distribution, etc. of the two population can shed light on the mechanism and sites of the acceleration. I will show that in some events the origin of both population appears to be the flare site while in others, with harder SEP spectra, in addition to acceleration at the flare site, there appears to be a need for a second stage re-acceleration in the associated fast Coronal Mass Ejection (CME) environment. This scenario can also describe a similar dichotomy that exists between the so called impulsive, highly enriched (3He and heavy ions) and softer SEP ion events, and stronger more gradual SEP events with near normal ionic abundances and harder spectra. I will also describe under what conditions such hardening can be achieved.

  13. Terahertz-driven linear electron acceleration

    CERN Document Server

    Nanni, Emilio Alessandro; Ravi, Koustuban; Fallahi, Arya; Moriena, Gustavo; Miller, R J Dwayne; Kärtner, Franz X

    2014-01-01

    The cost, size and availability of electron accelerators is dominated by the achievable accelerating gradient. Conventional high-brightness radio-frequency (RF) accelerating structures operate with 30-50 MeV/m gradients. Electron accelerators driven with optical or infrared sources have demonstrated accelerating gradients orders of magnitude above that achievable with conventional RF structures. However, laser-driven electron accelerators require intense sources and suffer from low bunch charge, sub-micron tolerances and sub-femtosecond timing requirements due to the short wavelength of operation. Here, we demonstrate the first linear acceleration of electrons with keV energy gain using optically-generated terahertz (THz) pulses. THz-driven accelerating structures enable high-gradient electron accelerators with simple accelerating structures, high repetition rates and significant charge per bunch. Increasing the operational frequency of accelerators into the THz band allows for greatly increased accelerating ...

  14. SNEAP 80: symposium of Northeastern Accelerator personnel

    International Nuclear Information System (INIS)

    Reports of operations are presented for twenty-seven facilities, along with reports on accelerators in progress, ion sources, insulating gases, charging systems, stripping foils, accelerating tubes, and upgraded accelerator systems

  15. SNEAP 80: symposium of Northeastern Accelerator personnel

    Energy Technology Data Exchange (ETDEWEB)

    Billen, J.H. (ed.)

    1980-01-01

    Reports of operations are presented for twenty-seven facilities, along with reports on accelerators in progress, ion sources, insulating gases, charging systems, stripping foils, accelerating tubes, and upgraded accelerator systems. (GHT)

  16. Atomic References for Measuring Small Accelerations

    Science.gov (United States)

    Maleki, Lute; Yu, Nan

    2009-01-01

    Accelerometer systems that would combine the best features of both conventional (e.g., mechanical) accelerometers and atom interferometer accelerometers (AIAs) have been proposed. These systems are intended mainly for use in scientific research aboard spacecraft but may also be useful on Earth in special military, geological, and civil-engineering applications. Conventional accelerometers can be sensitive, can have high dynamic range, and can have high frequency response, but they lack accuracy and long-term stability. AIAs have low frequency response, but they offer high sensitivity, and high accuracy for measuring small accelerations. In a system according to the proposal, a conventional accelerometer would be used to perform short-term measurements of higher-frequency components of acceleration, while an AIA would be used to provide consistent calibration of, and correction of errors in, the measurements of the conventional accelerometer in the lower-frequency range over the long term. A brief description of an AIA is prerequisite to a meaningful description of a system according to the proposal. An AIA includes a retroreflector next to one end of a cell that contains a cold cloud of atoms in an ultrahigh vacuum. The atoms in the cloud are in free fall. The retroreflector is mounted on the object, the acceleration of which is to be measured. Raman laser beams are directed through the cell from the end opposite the retroreflector, then pass back through the cell after striking the retroreflector. The Raman laser beams together with the cold atoms measure the relative acceleration, through the readout of the AIA, between the cold atoms and the retroreflector.

  17. Variable Acceleration Force Calibration System (VACS)

    Science.gov (United States)

    Rhew, Ray D.; Parker, Peter A.; Johnson, Thomas H.; Landman, Drew

    2014-01-01

    Conventionally, force balances have been calibrated manually, using a complex system of free hanging precision weights, bell cranks, and/or other mechanical components. Conventional methods may provide sufficient accuracy in some instances, but are often quite complex and labor-intensive, requiring three to four man-weeks to complete each full calibration. To ensure accuracy, gravity-based loading is typically utilized. However, this often causes difficulty when applying loads in three simultaneous, orthogonal axes. A complex system of levers, cranks, and cables must be used, introducing increased sources of systematic error, and significantly increasing the time and labor intensity required to complete the calibration. One aspect of the VACS is a method wherein the mass utilized for calibration is held constant, and the acceleration is changed to thereby generate relatively large forces with relatively small test masses. Multiple forces can be applied to a force balance without changing the test mass, and dynamic forces can be applied by rotation or oscillating acceleration. If rotational motion is utilized, a mass is rigidly attached to a force balance, and the mass is exposed to a rotational field. A large force can be applied by utilizing a large rotational velocity. A centrifuge or rotating table can be used to create the rotational field, and fixtures can be utilized to position the force balance. The acceleration may also be linear. For example, a table that moves linearly and accelerates in a sinusoidal manner may also be utilized. The test mass does not have to move in a path that is parallel to the ground, and no re-leveling is therefore required. Balance deflection corrections may be applied passively by monitoring the orientation of the force balance with a three-axis accelerometer package. Deflections are measured during each test run, and adjustments with respect to the true applied load can be made during the post-processing stage. This paper will

  18. Accelerator technology working group summary

    International Nuclear Information System (INIS)

    A summary is presented of workshop deliberations on basic scaling, the economic viability of laser drive power for HEP accelerators, the availability of electron beam injectors for near-term experiments, and a few very general remarks on technology issues

  19. 1988 linear accelerator conference proceedings

    International Nuclear Information System (INIS)

    This report contains papers presented at the 1988 Linear Accelerator Conference. A few topics covered are beam dynamics; beam transport; superconducting components; free electron lasers; ion sources; and klystron research

  20. Accelerator and fusion research division

    International Nuclear Information System (INIS)

    This report contains brief discussions on research topics in the following area: Heavy-Ion Fusion Accelerator Research; Magnetic Fusion Energy; Advanced Light Source; Center for Beam Physics; Superconducting Magnets; and Bevalac Operations

  1. Electrodynamics acceleration of electrical dipoles

    CERN Document Server

    Dolya, S N

    2013-01-01

    This article considers the acceleration of electric dipoles consisting of thin metal plates and dielectric (barium titanate). The dipoles are of a cylindrical shape with a diameter of the cylinder two centimeters and length one centimeter. Capacity of the parallel-plate capacitor is three hundred picofarads and it is charged up to the voltage of two hundred eighty kilovolts. Pre-acceleration of the electric dipoles till velocity one kilometer per second is reached by the gas-dynamic method. The finite acceleration is produced in a spiral waveguide, where the pulse is travelling with voltage amplitude seven hundreds kilovolts and power one hundred twenty-five megawatts. This pulse travels via the spiral waveguide and accelerates the injected electric dipoles in the longitudinal direction till the finite velocity eight and a half kilometers per second over length seven hundred and seventy meters.

  2. drift tube for linear accelerator

    CERN Multimedia

    A drift tube from the Linac 1. This was the first tank of the linear accelerator Linac1, the injection system for the Proton Synchrotron, It ran for 34 years (1958 - 1992). Protons entered at the far end and were accelerated between the copper drift tubes by an oscillating electromagnetic field. The field flipped 200 million times a second (200 MHz) so the protons spent 5 nanoseconds crossing a drift tube and a gap. Moving down the tank, the tubes and gaps had to get longer as the protons gained speed. The tank accelerated protons from 500 KeV to 10 MeV. Linac1 was also used to accelerate deutrons and alpha particles for the Intersecting Storage Rings and oxygen and sulpher ions for the Super Proton Synchrotron heavy ion programme.

  3. Advanced Superconducting Test Accelerator (ASTA)

    Data.gov (United States)

    Federal Laboratory Consortium — The Advanced Superconducting Test Accelerator (ASTA) facility will be based on upgrades to the existing NML pulsed SRF facility. ASTA is envisioned to contain 3 to...

  4. Prototype of industrial electrons accelerator

    International Nuclear Information System (INIS)

    The interest and the necessity of Mexico's industry in the use of irradiation process has been increased in the last years. As examples are the irradiation of combustion gases (elimination of NOx and SO2) and the polymer cross-linking between others. At present time at least twelve enterprises require immediately of them which have been contacted by electron accelerators suppliers of foreign countries. The first project step consisted in to identify the electrons accelerator type that in can be constructed in Mexico with the major number of possible equipment, instruments, components and acquisition materials local and useful for the major number of users. the characteristics of the accelerator prototype are: accelerator type transformer with multiple secondary insulated and rectifier circuits with a potential of 0.8 MV of voltage, the second step it consisted in an economic study that permitted to demonstrate the economic feasibility of its construction. (Author)

  5. Accelerating advanced-materials commercialization

    Science.gov (United States)

    Maine, Elicia; Seegopaul, Purnesh

    2016-05-01

    Long commercialization times, high capital costs and sustained uncertainty deter investment in innovation for advanced materials. With appropriate strategies, technology and market uncertainties can be reduced, and the commercialization of advanced materials accelerated.

  6. Particle accelerator; the Universe machine

    CERN Multimedia

    Yurkewicz, Katie

    2008-01-01

    "In summer 2008, scientists will switch on one of the largest machines in the world to search for the smallest of particle. CERN's Large Hadron Collider particle accelerator has the potential to chagne our understanding of the Universe."

  7. IGBT accelerated aging data set.

    Data.gov (United States)

    National Aeronautics and Space Administration — Preliminary data from thermal overstress accelerated aging using the aging and characterization system. The data set contains aging data from 6 devices, one device...

  8. An Energy Model of a Failure Mechanism and its Application

    Institute of Scientific and Technical Information of China (English)

    MA Xiao-ning; LU Zhen-zhou

    2003-01-01

    The energy expression is presented for a failure mechanism, and it is applied in an Accelerated Life Test (ALT) and an Accelerated Reliability Growth Test (ARGT). The conditions of the common failure mechanism are obtained. The essential relationship between the conditions and the Accelerated Factor (Af) is proposed by using the energy model.

  9. 50 years of research on particle acceleration in the heliosphere

    Science.gov (United States)

    Fisk, L. A.

    2015-09-01

    In 1965, and through the late 1960s, the heliosphere was considered to be a passive place, an impediment to the information on the galaxy contained in galactic cosmic ray observations, and on the Sun, from solar energetic particles. All this changed in the early 1970s with the discovery of the Anomalous Cosmic Rays (ACRs), and the subsequent acceptance that the ACRs are ionized interstellar neutral gas that is accelerated in the heliosphere by four orders of magnitude in energy. In the mid-1970s, Pioneer 10 & 11 observations provided direct evidence of acceleration. In 1977-78, diffusive shock acceleration was introduced, and subsequently developed in detail, providing compelling explanations for, e.g., the observed acceleration in co-rotating interaction regions, and a likely explanation for the acceleration of ACRs at the termination shock of the solar wind. In 2004 and 2008, the Voyagers crossed the termination shock, did not observe the acceleration of the ACRs, but did observe that low- energy particles, up to a few MeV/nucleon, had identical spectra downstream from the termination shock, a distribution function that is a power law in particle speed with a spectral index of -5. When Voyager 1 reached ∼120 AU, where the high-energy ACRs are at peak intensity, the ACR spectrum is also a -5 spectrum. Moreover, observations of suprathermal tails in the solar wind in the inner solar system have a -5 spectrum, often peaking downstream, but not at shocks. These observations led to the development of a new acceleration mechanism, the pump acceleration mechanism of Fisk & Gloeckler, which can account for all the observed -5 spectra.

  10. Accelerated Development of Organizational Talent

    OpenAIRE

    Korotov, Konstantin

    2007-01-01

    This working paper explores the challenges of accelerated development of organizational talent. The meaning of the word "accelerated" is that such development takes place at a pace that is significantly higher than that of "traditional" development that allows an individual to learn the intricacies of the current job, observe incumbents in a higher level position (usually, one level up), practice elements of the boss' job when being delegated tasks, undergoing formal training, or benefiting f...

  11. Electron Cloud Effects in Accelerators

    OpenAIRE

    Furman, M.A.

    2014-01-01

    Abstract 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 [1?22]. In addition, the proceedings of the various flavors of Particle Accelerator Conferences [23] contain a large number of EC-related publications. The ICFA Beam Dynamics...

  12. Particle accelerators and scientific culture

    International Nuclear Information System (INIS)

    A historical review of fifty years of physics around particle accelerators, from the first nuclear reactions produced by beams of artificially accelerated particles to the large multinational projects now under discussion. The aim is to show how our description of natural phenomena has been shaped by advances in theoretical understanding, the development of new techniques, and the characters of men. Large use has been made of quotations from many of the scientists involved. (Auth.)

  13. Particle accelerators and scientific culture

    International Nuclear Information System (INIS)

    A historical review of fifty years of physics around particle accelerators, from the first nuclear reactions produced by beams of artificially accelerated particles to the large multinational projects now under discussion. The aim is to show how the description of natural phenomena has been shaped by advances in theoretical understanding, the development of new techniques, and the characters of men. Large use has been made of quotations from many of the scientists involved. (Auth.)

  14. The Beta Tech electron accelerator

    International Nuclear Information System (INIS)

    After describing the background of the Swedish Electron Sterilization Centre, the proposed linear accelerator sterilization plant is outlined. The accelerator will produce electrons of energy 10 MeV and a beam power of 30 KW. The handling system, control and identification systems are also described. Documentation will be designed around a bar code system on line to a computer. The various uses of dosimetry in plant performance and process control are described. (U.K.)

  15. Dark Energy or local acceleration?

    CERN Document Server

    Feoli, Antonio

    2016-01-01

    We find that an observer with a suitable acceleration relative to the frame comoving whit the cosmic fluid, in the context of the FRW decelerating universe, measures the same cosmological redshift as the LambdaCDM model. The estimated value of this acceleration is beta = 1.4x10^-9m/s^2. The problem of a too high peculiar velocity can be solved assuming, for the observer, a sort of helical motion.

  16. Test accelerator for linear collider

    International Nuclear Information System (INIS)

    KEK has proposed to build Test Accelerator Facility (TAF) capable of producing a 2.5 GeV electron beam for the purpose of stimulating R ampersand D for linear collider in TeV region. The TAF consists of a 1.5 GeV S-band linear accelerator, 1.5 GeV damping ring and 1.0 GeV X-band linear accelerator. The TAF project will be carried forward in three phases. Through Phase-I and Phase-II, the S-band and X-band linacs will be constructed, and in Phase-III, the damping ring will be completed. The construction of TAF Phase-I has started, and the 0.2 GeV S-band injector linac has been almost completed. The Phase-I linac is composed of a 240 keV electron gun, subharmonic bunchers, prebunchers and traveling buncher followed by high-gradient accelerating structures. The SLAC 5045 klystrons are driven at 450 kV in order to obtain the rf-power of 100 MW in a 1 μs pulse duration. The rf-power from a pair of klystrons are combined into an accelerating structure. The accelerating gradient up to 100 MeV/m will be obtained in a 0.6 m long structure. 5 refs., 3 figs., 2 tabs

  17. Ponderomotive Acceleration by Relativistic Waves

    CERN Document Server

    Lau, Calvin; Yeh, Po-Chun; Luk, Onnie; McClenaghan, Joseph; Ebisuzaki, Toshikazu; Tajima, Toshiki

    2014-01-01

    In the extreme high intensity regime of electromagnetic (EM) waves in plasma, the acceleration process is found to be dominated by the ponderomotive acceleration (PA). While the wakefields driven by the ponderomotive force of the relativistic intensity EM waves are important, they may be overtaken by the PA itself in the extreme high intensity regime when the dimensionless vector potential $a_0$ of the EM waves far exceeds unity. The energy gain by this regime (in 1D) is shown to be (approximately) proportional to $a_0^2$. Before reaching this extreme regime, the coexistence of the PA and the wakefield acceleration (WA) is observed where the wave structures driven by the wakefields show the phenomenon of multiple and folded wave-breakings. Investigated are various signatures of the acceleration processes such as the dependence on the mass ratio for the energy gain as well as the energy spectral features. The relevance to high energy cosmic ray acceleration and to the relativistic laser acceleration is conside...

  18. High-Intensity Proton Accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Jay L. Hirshfield

    2011-12-27

    Analysis is presented for an eight-cavity proton cyclotron accelerator that could have advantages as compared with other accelerators because of its potentially high acceleration gradient. The high gradient is possible since protons orbit in a sequence of TE111 rotating mode cavities of equally diminishing frequencies with path lengths during acceleration that greatly exceed the cavity lengths. As the cavities operate at sequential harmonics of a basic repetition frequency, phase synchronism can be maintained over a relatively wide injection phase window without undue beam emittance growth. It is shown that use of radial vanes can allow cavity designs with significantly smaller radii, as compared with simple cylindrical cavities. Preliminary beam transport studies show that acceptable extraction and focusing of a proton beam after cyclic motion in this accelerator should be possible. Progress is also reported on design and tests of a four-cavity electron counterpart accelerator for experiments to study effects on beam quality arising from variations injection phase window width. This device is powered by four 500-MW pulsed amplifiers at 1500, 1800, 2100, and 2400 MHz that provide phase synchronous outputs, since they are driven from a with harmonics derived from a phase-locked 300 MHz source.

  19. Vacuum Brazing of Accelerator Components

    International Nuclear Information System (INIS)

    Commonly used materials for accelerator components are those which are vacuum compatible and thermally conductive. Stainless steel, aluminum and copper are common among them. Stainless steel is a poor heat conductor and not very common in use where good thermal conductivity is required. Aluminum and copper and their alloys meet the above requirements and are frequently used for the above purpose. The accelerator components made of aluminum and its alloys using welding process have become a common practice now a days. It is mandatory to use copper and its other grades in RF devices required for accelerators. Beam line and Front End components of the accelerators are fabricated from stainless steel and OFHC copper. Fabrication of components made of copper using welding process is very difficult and in most of the cases it is impossible. Fabrication and joining in such cases is possible using brazing process especially under vacuum and inert gas atmosphere. Several accelerator components have been vacuum brazed for Indus projects at Raja Ramanna Centre for Advanced Technology (RRCAT), Indore using vacuum brazing facility available at RRCAT, Indore. This paper presents details regarding development of the above mentioned high value and strategic components/assemblies. It will include basics required for vacuum brazing, details of vacuum brazing facility, joint design, fixturing of the jobs, selection of filler alloys, optimization of brazing parameters so as to obtain high quality brazed joints, brief description of vacuum brazed accelerator components etc.

  20. Accelerated Testing Validation

    Energy Technology Data Exchange (ETDEWEB)

    Mukundan, Rangachary; James, Greg; Davey, John; Langlois, David; Torraco, Dennis; Yoon, Wonseok; Weber, Adam Z; Borup, Rodney L.

    2011-07-01

    The DOE Fuel Cell technical team recommended ASTs were performed on 2 different MEAs (designated P5 and HD6) from Ballard Power Systems. These MEAs were also incorporated into stacks and operated in fuel cell bus modules that were either operated in the field (three P5 buses) in Hamburg, or on an Orange county transit authority drive cycle in the laboratory (HD6 bus module). Qualitative agreement was found in the degradation mechanisms and rates observed in the AST and in the field. The HD6 based MEAs exhibited lower voltage degradation rates (due to catalyst corrosion) and slower membrane degradation rates in the field as reflected by their superior performance in the high potential hold and open-circuit potential AST tests. The quantitative correlation of the degradation rates will have to take into account the various stressors in the field including temperature, relative humidity, start/stops and voltage cycles.

  1. Orders of Fermi- and Plasma-Accelerations of Cosmic Rays

    CERN Document Server

    Tawfik, A

    2010-01-01

    The generic acceleration model for ultra high energy cosmic rays, which has been introduced in {\\tt 1006.5708 [astro-ph.HE]}, suggests various types of electromagnetic interactions between cosmic charged particles and the different types of the plasma fields, which are assumed to have general configurations, spatially and temporally. The well-known Fermi acceleration mechanisms are also included in the model. Meanwhile Fermi mechanisms in non-relativistic limit adhere first- and second-order of $\\beta$, the ratio of particle's velocity relative to the velocity of the stellar magnetic cloud, in the plasma field sector, $\\beta$ does not play any role, i.e. zero-order. In the relativistic limit, the orders of Fermi acceleration are only possible, when applying the corresponding conditions, either elastic scatterings or shock waves. Furthermore, it is found that the coefficients of $\\beta$ are functions of the initial and final velocities and the characteristic Larmor radius.

  2. The acceleration of cosmic rays by shock waves

    International Nuclear Information System (INIS)

    The direct transfer of energy to cosmic rays from supersonic motions of the background medium via shock waves, by means of an efficient first order Fermi mechanism, is considered. The acceleration of cosmic rays by shock waves is most effective in the dilute and hot, 1,000,000-K component of the interstellar medium. There is no limit to the energy that can be achieved by shock acceleration, if enough time is available and the particles can be contained in the vicinity of the shock. The two basic first order Fermi mechanisms contributing to the overall process of shock acceleration of cosmic rays are reflection at, or transmission through, the magnetic field jump associated with the shock, and multiple reflection between the media upstream and downstream of the shock, due to the presence of waves that scatter the particles in pitch angle

  3. Collective acceleration of protons by the plasma waves in a counterstreaming electron beam

    International Nuclear Information System (INIS)

    A novel advanced accelerator is proposed. The counterstreaming electron beam accelerator relies on the same physical mechanism as that of the plasma accelerator but replaces the stationary plasma in the plasma accelerator by a magnetized relativistic electron beam, drifting antiparallel to the driving source and the driven particles, as the wave supporting medium. The plasma wave in a counterstreaming electron beam can be excited either by a density-ramped driving electron beam or by properly beating two laser beams. The fundamental advantages of the counterstreaming electron beam accelerator over the plasma accelerator are a longer and tunable plasma wavelength, a longer pump depletion length or a larger transformer ratio, and easier pulse shaping for the driving source and the driven beam. Thus the energy gain of the driven particles can be greatly enhanced whereas the trapping threshold can be dramatically reduced so as to admit the possibility for proton acceleration

  4. New frontier of laser particle acceleration: driving protons to 80 MeV by radiation pressure

    CERN Document Server

    Kim, I Jong; Kim, Chul Min; Kim, Hyung Taek; Lee, Chang-Lyoul; Choi, Il Woo; Singhal, Himanshu; Sung, Jae Hee; Lee, Seong Ku; Lee, Hwang Woon; Nickles, Peter V; Jeong, Tae Moon; Nam, Chang Hee

    2014-01-01

    The radiation pressure acceleration (RPA) of charged particles has been considered a challenging task in laser particle acceleration. Laser-driven proton/ion acceleration has attracted considerable interests due to its underlying physics and potential for applications such as high-energy density physics, ultrafast radiography, and cancer therapy. Among critical issues to overcome the biggest challenge is to produce energetic protons using an efficient acceleration mechanism. The proton acceleration by radiation pressure is considerably more efficient than the conventional target normal sheath acceleration driven by expanding hot electrons. Here we report the generation of 80-MeV proton beams achieved by applying 30-fs circularly polarized laser pulses with an intensity of 6.1 x 1020 W/cm2 to ultrathin targets. The radiation pressure acceleration was confirmed from the obtained optimal target thickness, quadratic energy scaling, polarization dependence, and 3D-PIC simulations. We expect this fast energy scalin...

  5. Analysis on Mechanism of Flowing Cooling Water on Ship Pipeline Accelerated Corrosion%流动冷却水对船舶管路的冲刷加速腐蚀机理

    Institute of Scientific and Technical Information of China (English)

    杨元龙

    2015-01-01

    为研究船舶冷却水管路流动冲蚀失效过程,明晰冷却水管路易发生腐蚀破损的薄弱部位,建立船舶冷却水系统管路数理模型,采用基于CFD数值模拟的方法研究冷却水管路系统压力场和流速场运行特性,结合引发流动冷却水冲蚀管道的机理,得到弯头、三通管等易损部位的流速、湍动能、剪切应力和压力的参数分布。分析冷却水管路内流场,判定三通管流出支管易遭受冲击腐蚀和冲刷腐蚀,三通管焊缝区域易遭受空泡腐蚀,弯管中游靠内壁区域受冲击腐蚀、冲刷腐蚀和空泡腐蚀。%For the study of ship cooling water flow erosion failure process, weak position coming from corrosion damages for cooling water pipe were cleared.The mathematical and physical models of ship cooling water pipeline are established.The opera-tion characteristics with pressure and velocity field for the cooling water pipeline are analyzed by using CFD simulation.Three mechanisms comprised impingement corrosion, brush corrosion and cavitation erosion, which could induce pipeline erosion by flowing cooling water are inserted.The key predicting parameter such as local velocity, turbulence kinetic energy, wall shears and pressure around T-junction and elbow regions are obtained.Based on the analysis of flow field within the cooling water pipe-line, the calculated results indicated that impingement corrosion and brush corrosion are easy to come up.Cavitation erosion is easy to take place at the region of weld joint for T-junction.All of impingement corrosion, brush corrosion and cavitation erosion can happen midstream elbow rely on inner wall region.

  6. Accelerator and electrodynamics capability review

    Energy Technology Data Exchange (ETDEWEB)

    Jones, Kevin W [Los Alamos National Laboratory

    2010-01-01

    Los Alamos National Laboratory (LANL) uses capability reviews to assess the science, technology and engineering (STE) quality and institutional integration and to advise Laboratory Management on the current and future health of the STE. Capability reviews address the STE integration that LANL uses to meet mission requirements. The Capability Review Committees serve a dual role of providing assessment of the Laboratory's technical contributions and integration towards its missions and providing advice to Laboratory Management. The assessments and advice are documented in reports prepared by the Capability Review Committees that are delivered to the Director and to the Principal Associate Director for Science, Technology and Engineering (PADSTE). Laboratory Management will use this report for STE assessment and planning. LANL has defined fifteen STE capabilities. Electrodynamics and Accelerators is one of the seven STE capabilities that LANL Management (Director, PADSTE, technical Associate Directors) has identified for review in Fiscal Year (FY) 2010. Accelerators and electrodynamics at LANL comprise a blend of large-scale facilities and innovative small-scale research with a growing focus on national security applications. This review is organized into five topical areas: (1) Free Electron Lasers; (2) Linear Accelerator Science and Technology; (3) Advanced Electromagnetics; (4) Next Generation Accelerator Concepts; and (5) National Security Accelerator Applications. The focus is on innovative technology with an emphasis on applications relevant to Laboratory mission. The role of Laboratory Directed Research and Development (LDRD) in support of accelerators/electrodynamics will be discussed. The review provides an opportunity for interaction with early career staff. Program sponsors and customers will provide their input on the value of the accelerator and electrodynamics capability to the Laboratory mission.

  7. Plasma Beat-Wave Acceleration

    Science.gov (United States)

    Clayton, Christopher E.

    2002-04-01

    Among all the advanced accelerator concepts that use lasers as the power source, most of the effort to date has been with the idea of using a laser pulse to excite a accelerating mode in a plasma. Within this area, there are a variety of approaches for creating the accelerating mode, as indicated by the other talks in this session. What is common to these approaches is the physics of how a laser pulse pushes on plasma electrons to organize electron-density perturbations, the sources of the ultra-high (> GeV/M) accelerating gradients. It is the "ponderomotive force", proportional to the local gradient of the of the laser intensity, that pushes plasma electrons forward (on the leading edge of the pulse) and backwards (on the trailing edge) which leads to harmonic motion of the electrons. As the laser pulse moves through the plasma at group velocity Vg c, the oscillating electrons show up macroscopically as a plasma mode or wave with frequency w equal to the plasma frequency and k = w/Vg. For short laser pulses, this is the Laser Wakefield Accelerator (LWFA) concept. Closely related is the Plasma Beat-Wave Acceleration (PBWA) concept. Here, the laser pulse that perturbs the plasma is composed of two closely-spaced frequencies that "beat", i.e., periodically constructively and destructively interfere, forming an electromagnetic beat wave. One can visualize this as a train of short pulses. If this beating frequency is set to the plasma frequency, then each pulse in the train will reinforce the density perturbation caused by the previous pulse. The principal advantage of multiple pulses driving up the plasma wave as opposed to a single pulse is in efficiency, allowing for the production of relatively large diameter (more 1-D like) accelerating modes. In this talk I will discuss past, current and planned PBWA experiments which are taking place at UCLA, RAL in England, and LULI in France.

  8. CAS Accelerator Physics (RF for Accelerators) in Denmark

    CERN Multimedia

    Barbara Strasser

    2010-01-01

    The CERN Accelerator School (CAS) and Aarhus University jointly organised a specialised course on RF for Accelerators, at the Ebeltoft Strand Hotel, Denmark from 8 to 17 June 2010.   Caption The challenging programme focused on the introduction of the underlying theory, the study and the performance of the different components involved in RF systems, the RF gymnastics and RF measurements and diagnostics. This academic part was supplemented with three afternoons dedicated to practical hands-on exercises. The school was very successful, with 100 participants representing 25 nationalities. Feedback from the participants was extremely positive, praising the expertise and enthusiasm of the lecturers, as well as the high standard and excellent quality of their lectures. In addition to the academic programme, the participants were able to visit a small industrial exhibition organised by Aarhus University and take part in a one-day excursion consisting of a visit of the accelerators operated ...

  9. The Accelerator Markup Language and the Universal Accelerator Parser

    Energy Technology Data Exchange (ETDEWEB)

    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

    2006-10-06

    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.

  10. CAS CERN Accelerator School third general accelerator physics course

    International Nuclear Information System (INIS)

    The general course on accelerator physics given in Salamanca, Spain, closely followed those organised by the CERN Accelerator School at Gif-sur-Yvette, Paris in 1984, and at Aarhus, Denmark in 1986 and whose proceedings were published as CERN Yellow Reports 85-19 (1985) and 87-10 (1987) respectively. However, certain topics 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 beam-cooling concepts, Liouville's theorem and emittance, emittance dilution in transfer lines, weak-betatron coupling, diagnostics, while the seminars are on positron and electron sources, linac structures and the LEP L3 experiment, together with industrial aspects of particle accelerators. Also included are errata and addenda to the Yellow Reports mentioned above. (orig.)

  11. CAS CERN Accelerator School: Fourth general accelerator physics course

    International Nuclear Information System (INIS)

    The fourth CERN Accelerator School (CAS) basic course on General Accelerator Physics was given at KFA, Juelich, from 17 to 28 September 1990. Its syllabus was based on the previous similar courses held at Gif-sur-Yvette in 1984, Aarhus 1986, and Salamanca 1988, and whose proceedings were published as CERN Reports 85-19, 87-10, and 89-05, respectively. However, certain topics were treated in a different way, improved or extended, while new subjects were introduced. All of these appear in the present proceedings, which include lectures or seminars on the history and applications of accelerators, phase space and emittance, chromaticity, beam-beam effects, synchrotron radiation, radiation damping, tune measurement, transition, electron cooling, the designs of superconducting magnets, ring lattices, conventional RF cavities and ring RF systems, and an introduction to cyclotrons. (orig.)

  12. CAS CERN Accelerator School. Third advanced accelerator physics course

    International Nuclear Information System (INIS)

    The third version of the CERN Accelerator School's (CAS) advanced course on General Accelerator Physics was given at Uppsala University from 18-29 September, 1989. Its syllabus was based on the previous courses held in Oxford, 1985 and Berlin, 1987 whose proceedings were published as CERN Yellow Reports 87-03 and 89-01 respectively. However, the opportunity was taken to emphasize the physics of small accelerators and storage rings, to present some topics in new ways, and to introduce new seminars. Thus the lectures contained in the present volume include chromaticity, dynamic aperture, kinetic theory, Landau damping, ion-trapping, Schottky noise, laser cooling and small ring lattice problems while the seminars include interpretation of numerical tracking, internal targets and living with radiation. (orig.)

  13. Particle Acceleration at Relativistic and Ultra-Relativistic Shock Waves

    Science.gov (United States)

    Meli, A.

    We perform Monte Carlo simulations using diffusive shock acceleration at relativistic and ultra-relativistic shock waves. High upstream flow gamma factors are used, Γ=(1-uup2/c2)-0.5, which are relevant to models of ultra-relativistic particle shock acceleration in the central engines and relativistic jets of Active Galactic Nuclei (AGN) and in Gamma-Ray Burst (GRB) fireballs. Numerical investigations are carried out on acceleration properties in the relativistic and ultra-relativistic flow regime (Γ ˜ 10-1000) concerning angular distributions, acceleration time scales, particle energy gain versus number of crossings and spectral shapes. We perform calculations for both parallel and oblique sub-luminal and super-luminal shocks. For parallel and oblique sub-luminal shocks, the spectra depend on whether or not the scattering is represented by pitch angle diffusion or by large angle scattering. The large angle case exhibits a distinctive structure in the basic power-law spectrum not nearly so obvious for small angle scattering. However, both cases yield a significant 'speed-up' of acceleration rate when compared with the conventional, non-relativistic expression, tacc=[c/(uup-udown)] (λup/uup+λdown/udown). An energization by a factor Γ2 for the first crossing cycle and a large energy gains for subsequent crossings as well as the high 'speed-up' factors found, are important in supporting past works, especially the models developed by Vietri and Waxman on ultra-high energy cosmic ray, neutrino and gamma-ray production in GRB. For oblique super-luminal shocks, we calculate the energy gain and spectral shape for a number of different inclinations. For this case the acceleration of particles is 'pictured' by a shock drift mechanism. We use high gamma flows with Lorentz factors in the range 10-40 which are relevant to ultra-relativistic shocks in AGN accretion disks and jets. In all investigations we closely follow the particle's trajectory along the magnetic field

  14. Particle acceleration in tangential discontinuities by lower hybrid waves

    Directory of Open Access Journals (Sweden)

    D. Spicer

    2002-01-01

    Full Text Available We consider the role that the lower-hybrid wave turbulence plays in providing the necessary resistivity at collisionless reconnection sights. The mechanism for generating the waves is considered to be the lower-hybrid drift instability. We find that the level of the wave amplitude is sufficient enough to heat and accelerate both electrons and ions.

  15. Radial acceleration relation from screening of fifth forces

    CERN Document Server

    Burrage, Clare; Millington, Peter

    2016-01-01

    We show that the radial acceleration relation for rotationally-supported galaxies may be explained, in the absence of cold dark matter, by a non-minimally coupled scalar field, whose fifth forces are partially screened on galactic scales by the symmetron mechanism. If realised in nature, this effect could have a significant impact on the inferred density of dark matter halos.

  16. A MEMS Energy Harvesting Device for Vibration with Low Acceleration

    DEFF Research Database (Denmark)

    Triches, Marco; Wang, Fei; Crovetto, Andrea;

    2012-01-01

    We propose a polymer electret based energy harvesting device in order to extract energy from vibration sources with low acceleration. With MEMS technology, a silicon structure is fabricated which can resonate in 2D directions. Thanks to the excellent mechanical properties of the silicon material...

  17. Neck forces and moments and head accelerations in side impact

    NARCIS (Netherlands)

    Yoganandan, N.; Pintar, F.A.; Maiman, D.J.; Philippens, M.M.G.M.; Wismans, J.S.H.M.

    2009-01-01

    Objectives: Although side-impact sled studies have investigated chest, abdomen, and pelvic injury mechanics, determination of head accelerations and the associated neck forces and moments is very limited. The purpose of the present study was therefore to determine the temporal forces and moments at

  18. Accelerated Leach Test(s) Program: Annual report

    Energy Technology Data Exchange (ETDEWEB)

    Dougherty, D.R.; Pietrzak, R.F.; Fuhrmann, M.; Colombo, P.

    1986-09-01

    A computerized data base of LLW leaching data has been developed. Long-term tests on portland cement, bitumen and vinyl ester-styrene (VES) polymer waste forms containing simulated wastes are underway which are designed to identify and evaluate factors that accelerate leaching without changing the mechanisms.

  19. Industrial Electron Accelerators Type ILU

    CERN Document Server

    Auslender, Vadim; Cheskidov, Vladimir; Faktorovich, Boris; Gorbunov, Vladimir; Gornakov, Igor; Nekhaev, V E; Panfilov, Alexander; Sidorov, Alexander; Tkachenko, Vadim; Tuvik, Alfred; Voronin, Leonid

    2005-01-01

    The report describes the electron accelerators of ILU series covering the energy range from 0.5 to 5 MeV with beam power up to 50 kW. The pulse linear accelerators type ILU are developed since 1970 in Budker institute of Nuclear Physics and are supplied to the industry. The ILU machines are purposed for wide application in various technological processes and designed for long continuous and round-the-clock work in industrial conditions. A principle of acceleration of electrons in the gap of HF resonator is used in the ILU machines. The HF resonator has toroidal form. The electron gun is placed in one of the protruding electrodes forming the accelerating gap of the resonator. The resonator is fed from HF autogenerator realized on the industrial triode, the feedback signal is given from the resonator. The absence of outer beam injection and usage of self-excited HF generator simplify the design of accelerator and ensure its reliable operation.

  20. A variable acceleration calibration system

    Science.gov (United States)

    Johnson, Thomas H.

    2011-12-01

    A variable acceleration calibration system that applies loads using gravitational and centripetal acceleration serves as an alternative, efficient and cost effective method for calibrating internal wind tunnel force balances. Two proof-of-concept variable acceleration calibration systems are designed, fabricated and tested. The NASA UT-36 force balance served as the test balance for the calibration experiments. The variable acceleration calibration systems are shown to be capable of performing three component calibration experiments with an approximate applied load error on the order of 1% of the full scale calibration loads. Sources of error are indentified using experimental design methods and a propagation of uncertainty analysis. Three types of uncertainty are indentified for the systems and are attributed to prediction error, calibration error and pure error. Angular velocity uncertainty is shown to be the largest indentified source of prediction error. The calibration uncertainties using a production variable acceleration based system are shown to be potentially equivalent to current methods. The production quality system can be realized using lighter materials and a more precise instrumentation. Further research is needed to account for balance deflection, forcing effects due to vibration, and large tare loads. A gyroscope measurement technique is shown to be capable of resolving the balance deflection angle calculation. Long term research objectives include a demonstration of a six degree of freedom calibration, and a large capacity balance calibration.