WorldWideScience

Sample records for beam blowup

  1. Controlled Transverse Blow-up of Highenergy Proton Beams for Aperture Measurements and Loss Maps

    CERN Document Server

    Hӧfle, W; Redaelli, S; Schmidt, R; Valuch, D; Wollmann, D; Zerlauth, M

    2012-01-01

    A technique was developed to blow-up transversely in a controlled way high energy proton beams in the LHC. The technique is based on band limited white noise excitation that is injected into the transverse damper feedback loop. The injected signal can be gated to selectively blow-up individual trains of bunches. The speed of transverse blow-up can be precisely controlled. This opens the possibility to perform safely and efficiently aperture measurements and loss maps with high intensity bunch trains well above stored beam energies that are considered to be safe. In particular, lengthy procedures for measurements at top energy, otherwise requiring multiple fills of individual bunches, can be avoided. In this paper, the method is presented and results from beam measurements are discussed and compared with alternative blowup methods.

  2. PSB beam longitudinal blow-up by phase modulation with the digital LLRF prototype system

    CERN Document Server

    Angoletta, M E; Butterworth, A; Findlay, A; Jaussi, M; Leinonen, P; Molendijk, J; Sanchez-Quesada, J

    2014-01-01

    The PSB will be upgraded to a new, Digital Low-Level RF (DLLRF) system in 2014 at the injectors’ restart after LS1. This DLLRF is an evolution of that successfully deployed in LEIR and comprises new hardware, software and implementation strategies. Machine development studies have been carried out in the PSB over recent years with the existing LEIR-style hardware installed in PSB ring four. These studies have allowed testing approaches and validating implementation strategies. This note focuses on a series of MDs carried out during the 2011 run where a new implementation of the longitudinal beam blow-up obtained by phase modulation was tested. Test results and effects on the beam are show for a CNGS-type beam. Finally, an overview is given of the final longitudinal blow-up implementation planned with the new hardware, which will be operationally deployed in 2014.

  3. Simple countermeasures against the TM110-beam-blowup-mode in biperiodic structures

    International Nuclear Information System (INIS)

    Euteneuer, H.; Herminghaus, H.; Schoeler, H.

    1984-01-01

    The two fundamental methods of fighting beam blow-up in rf-accelerating-structures are staggered detuning and selective Q-spoiling of their higher order modes. Biperiodic structures offer a very simple way of applying the latter technique of the most dangerous TM 110 -like blowup mode at 1.7 times the accelerating frequency: letting this mode propagate but giving a large gap to the TM 110 -passband. This gap must be positive for electric coupling (f(phi=0) =1.7c. With asymmetric coupling elements between the cavities of a structure, one has a simple tool for staggered detuning: a change of the relative orientation of these elements spreads the resonance frequencies not only of the TM 110 -mode, but of at least all dipole modes. (orig.)

  4. Vertical blow-up in a low-current, stored, laser-cooled ion beam

    CERN Document Server

    Madsen, N; Siegfried, L E; Hangst, J S; Nielsen, J

    2003-01-01

    Using a novel technique for real-time transverse beam profile diagnostics of a stored ion beam, we have observed the transverse size of a stored, laser-cooled ion beam. Earlier we observed that the density of the beam is independent of the beam current. At very low currents we observe an abrupt change in this behavior: the vertical beam size increases suddenly by about an order of magnitude. This observation implies a sudden change in the indirect vertical cooling mediated by intrabeam scattering. Our results have serious implications for the ultimate beam quality attainable by laser- cooling. (12 refs).

  5. Low-current, vertical blowup in a stored laser-cooled ion beam

    CERN Document Server

    Madsen, N; Nielsen, S; Siegfried, L E; Hangst, J S

    2001-01-01

    Using a novel technique for real-time transverse beam profile diagnostics of a stored ion beam, we have observed the transverse size of a stored laser-cooled ion beam. Earlier we observed that the density of the beam is independent of the beam current. At very low currents, we observe an abrupt change in this behavior: The vertical beam size increases suddenly by about an order of magnitude. This observation implies a sudden change in the indirect vertical cooling mediated by intrabeam scattering. Our results have serious implications for the ultimate beam quality attainable by laser cooling. (11 refs).

  6. New beam-based and direct magnetic waveform measurements of the BTx.KFA10(20) vertical recombination kickers and induced emittance blow-up simulations at 1.4 and 2 GeV

    CERN Document Server

    Forte, Vincenzo; Borburgh, Jan; Sermeus, Luc; CERN. Geneva. ATS Department

    2018-01-01

    In the framework of the LHC Injectors Upgrade (LIU) project [1], this document summarises a new reconstruction methodology for the measurement of the magnetic waveforms of the vertical re-combination kickers BT1.KFA10, BT4.KFA10 and BT2.KFA20, from data collected during several Machine Development (MD) sessions. The reconstruction has been performed in order to verify the LIU specification of the recombination kickers, which is required for a clean transfer of the longer bunches coming from the PSB after the upgrade. A beam-based methodology was developed to measure the transient magnetics dynamics of the kicker where the bunch length is comparable to the rise and/or fall times. These measurements represent a valuable way to reconstruct the mag-netic waveform of the kickers where removing them to make direct probe measurements is time consuming. A benchmarking of the beam-based measurements with field probe measurements is presented, together with realistic simulations of the vertical emittance blow-up at 1...

  7. Blowup for flat slow manifolds

    DEFF Research Database (Denmark)

    Kristiansen, Kristian Uldall

    2017-01-01

    In this paper, we present a way of extending the blowup method, in the formulation of Krupa and Szmolyan, to flat slow manifolds that lose hyperbolicity beyond any algebraic order. Although these manifolds have infinite co-dimensions, they do appear naturally in certain settings; for example, in (a......) the regularization of piecewise smooth systems by tanh, (b) a particular aircraft landing dynamics model, and finally (c) in a model of earthquake faulting. We demonstrate the approach using a simple model system and the examples (a) and (b)....

  8. Blowup for flat slow manifolds

    Science.gov (United States)

    Kristiansen, K. U.

    2017-05-01

    In this paper, we present a way of extending the blowup method, in the formulation of Krupa and Szmolyan, to flat slow manifolds that lose hyperbolicity beyond any algebraic order. Although these manifolds have infinite co-dimensions, they do appear naturally in certain settings; for example, in (a) the regularization of piecewise smooth systems by \\tanh , (b) a particular aircraft landing dynamics model, and finally (c) in a model of earthquake faulting. We demonstrate the approach using a simple model system and the examples (a) and (b).

  9. Blow-up: A Free Lunch?

    Directory of Open Access Journals (Sweden)

    Jan Koenderink

    2012-02-01

    Full Text Available We consider operations that change the size of images, either shrinks or blow-ups. Image processing offers numerous possibilities, put at everyone's disposal with such computer programs as Adobe Photoshop. We consider a different class of operations, aimed at immediate visual awareness, rather than pixel arrays. We demonstrate cases of blow-ups that do not sacrifice apparent resolution. This apparent information gain is due to “amodal occlusion.”

  10. Improved Longitudinal Blow-up and Shaving in the Booster

    CERN Document Server

    Hancock, S

    2013-01-01

    The low-intensity proton beam for p-Pb collisions in the LHC did not come back in the Booster at the beginning of 2013 anything like it had been set up at the end of 2012. In particular there were unexplained intensity fluctuations of ±100%. Although the root cause of the drift in performance was never established, its investigation revealed long-standing issues in the longitudinal plane which, when corrected, allowed single-bunch beams to be delivered with unprecedented reproducibility and control of both intensity and longitudinal emittance. The new approach was adopted for the ion run and subsequently for MDs at higher intensities, where it made possible a robust control of intensity at constant 6D phase space volume. Post-LS1, it may even provide a platform upon which to build a more exotic controlled longitudinal blow-up to generate higher intensity bunches with a flattened line density.

  11. Blow-up : A free lunch?

    NARCIS (Netherlands)

    Koenderink, J.J.; Richards, W.; Van Doorn, A.J.

    2012-01-01

    We consider operations that change the size of images, either shrinks or blow-ups. Image processing offers numerous possibilities, put at everyone’s disposal with such computer programs as Adobe Photoshop. We consider a different class of operations, aimed at immediate visual awareness, rather than

  12. Simultaneous and non-simultaneous blow-up and uniform blow-up profiles for reaction-diffusion system

    Directory of Open Access Journals (Sweden)

    Zhengqiu Ling

    2012-11-01

    Full Text Available This article concerns the blow-up solutions of a reaction-diffusion system with nonlocal sources, subject to the homogeneous Dirichlet boundary conditions. The criteria used to identify simultaneous and non-simultaneous blow-up of solutions by using the parameters p and q in the model are proposed. Also, the uniform blow-up profiles in the interior domain are established.

  13. Blow-up in nonlinear Schroedinger equations. II. Similarity structure of the blow-up singularity

    DEFF Research Database (Denmark)

    Rypdal, K.; Juul Rasmussen, Jens

    1986-01-01

    invariance and generalizations of the latter. This generalized "quasi-invariance" reveals the nature of the blow-up singularity and resolves an old controversy. Most of the previous work has been done on the cubic nonlinearity. We generalize the results to an arbitrary power nonlinearity....

  14. A Note on the Blow-up Pattern for a Parabolic Equation

    OpenAIRE

    Kohda, Atsuhito; Suzuki, Takashi

    1999-01-01

    We consider here some conditions on initial value for parabolic problem which guarantee the blow-up of a solution. Then we study the behaviour of blow-up solution near blow-up time, that is blow-up patterns.

  15. Heterotic Mini-landscape in blow-up

    CERN Document Server

    Bizet, Nana Geraldine Cabo

    2013-01-01

    Localization properties of fields in compact extra dimensions are crucial ingredients for string model building, particularly in the framework of orbifold compactifications. Realistic models often require a slight deviation from the orbifold point, that can be analyzed using field theoretic methods considering (singlet) fields with nontrivial vacuum expectation values. Some of these fields correspond to blow-up modes that represent the resolution of orbifold singularities. Improving on previous analyses we give here an explicit example of the blow-up of a model from the heterotic Mini-landscape. An exact identification of the blow-up modes at various fixed points and fixed tori with orbifold twisted fields is given. We match the massless spectra and identify the blow-up modes as non-universal axions of compactified string theory. We stress the important role of the Green-Schwarz anomaly polynomial for the description of the resolution of orbifold singularities.

  16. Blow-Ups in Generalized Kähler Geometry

    Science.gov (United States)

    van der Leer Durán, J. L.

    2018-02-01

    We study blow-ups in generalized Kähler geometry. The natural candidates for submanifolds to be blown-up are those which are generalized Poisson submanifolds for one of the two generalized complex structures and can be blown up in a generalized complex manner. We show that the bi-Hermitian structure underlying the generalized Kähler pair lifts to a degenerate bi-Hermitian structure on this blow-up. Then, using a deformation procedure based on potentials in Kähler geometry, we identify two concrete situations in which one can deform the degenerate structure on the blow-up into a non-degenerate one. We end with a study of generalized Kähler Lie groups and give a concrete example on {(S^1)^n × (S^3)^m}, for n + m even.

  17. Gradient blow-up in generalized Burgers and Boussinesq equations

    Science.gov (United States)

    Yushkov, E. V.; Korpusov, M. O.

    2017-12-01

    We study the influence of gradient non-linearity on the global solubility of initial-boundary value problems for a generalized Burgers equation and an improved Boussinesq equation which are used for describing one-dimensional wave processes in dissipative and dispersive media. For a large class of initial data, we obtain sufficient conditions for global insolubility and a bound for blow-up times. Using the Boussinesq equation as an example, we suggest a modification of the method of non-linear capacity which is convenient from a practical point of view and enables us to estimate the blow-up rate. We use the method of contraction mappings to study the possibility of instantaneous blow-up and short-time existence of solutions.

  18. Finite Time Blowup in a Realistic Food-Chain Model

    KAUST Repository

    Parshad, Rana

    2013-05-19

    We investigate a realistic three-species food-chain model, with generalist top predator. The model based on a modified version of the Leslie-Gower scheme incorporates mutual interference in all the three populations and generalizes several other known models in the ecological literature. We show that the model exhibits finite time blowup in certain parameter range and for large enough initial data. This result implies that finite time blowup is possible in a large class of such three-species food-chain models. We propose a modification to the model and prove that the modified model has globally existing classical solutions, as well as a global attractor. We reconstruct the attractor using nonlinear time series analysis and show that it pssesses rich dynamics, including chaos in certain parameter regime, whilst avoiding blowup in any parameter regime. We also provide estimates on its fractal dimension as well as provide numerical simulations to visualise the spatiotemporal chaos.

  19. Strong-strong beam-beam simulation on parallel computer

    Energy Technology Data Exchange (ETDEWEB)

    Qiang, Ji

    2004-08-02

    The beam-beam interaction puts a strong limit on the luminosity of the high energy storage ring colliders. At the interaction points, the electromagnetic fields generated by one beam focus or defocus the opposite beam. This can cause beam blowup and a reduction of luminosity. An accurate simulation of the beam-beam interaction is needed to help optimize the luminosity in high energy colliders.

  20. Strong-strong beam-beam simulation on parallel computer

    International Nuclear Information System (INIS)

    Qiang, Ji

    2004-01-01

    The beam-beam interaction puts a strong limit on the luminosity of the high energy storage ring colliders. At the interaction points, the electromagnetic fields generated by one beam focus or defocus the opposite beam. This can cause beam blowup and a reduction of luminosity. An accurate simulation of the beam-beam interaction is needed to help optimize the luminosity in high energy colliders

  1. Blowup in the complex Ginzburg-Landau equation

    NARCIS (Netherlands)

    Schans, Martin van der

    2013-01-01

    In this thesis, we study the stability of a finite-time blowup solution of a partial di erential equation (PDE). Partial di erential equations can be used to model phenomena in a wide range of applications. Examples of well known partial di erential equations are: the heat equation which models heat

  2. Periodicity and blowup in a two-species cooperating model

    DEFF Research Database (Denmark)

    Lin, Zhigui; Liu, Jiahong; Pedersen, Michael

    2011-01-01

    for the same system are then given. It is shown that periodic solutions exist if the intra-specific competitions are strong whereas blowup solutions exist under certain conditions if the intra-specific competitions are weak. Numerical simulations and a brief discussion are also presented in the last section....

  3. Blowup Analysis for a Nonlocal Diffusion Equation with Reaction and Absorption

    Directory of Open Access Journals (Sweden)

    Yulan Wang

    2012-01-01

    Full Text Available We investigate a nonlocal reaction diffusion equation with absorption under Neumann boundary. We obtain optimal conditions on the exponents of the reaction and absorption terms for the existence of solutions blowing up in finite time, or for the global existence and boundedness of all solutions. For the blowup solutions, we also study the blowup rate estimates and the localization of blowup set. Moreover, we show some numerical experiments which illustrate our results.

  4. Asymptotic properties of blow-up solutions in reaction-diffusion equations with nonlocal boundary flux

    Science.gov (United States)

    Liu, Bingchen; Dong, Mengzhen; Li, Fengjie

    2018-04-01

    This paper deals with a reaction-diffusion problem with coupled nonlinear inner sources and nonlocal boundary flux. Firstly, we propose the critical exponents on nonsimultaneous blow-up under some conditions on the initial data. Secondly, we combine the scaling technique and the Green's identity method to determine four kinds of simultaneous blow-up rates. Thirdly, the lower and the upper bounds of blow-up time are derived by using Sobolev-type differential inequalities.

  5. Numerical study of blow-up in the Davey-Stewartson system

    KAUST Repository

    Klein, Christian

    2013-03-01

    Nonlinear dispersive partial differential equations such as the nonlinear Schrödinger equations can have solutions that blow up. We numerically study the long time behavior and potential blow-up of solutions to the focusing Davey-Stewartson II equation by analyzing perturbations of the lump and the Ozawa solutions. It is shown in this way that both are unstable to blow-up and dispersion, and that blow-up in the Ozawa solution is generic.

  6. Remarks on the Blow-Up Solutions for the Critical Gross-Pitaevskii Equation

    Directory of Open Access Journals (Sweden)

    Xiaoguang Li

    2013-01-01

    Full Text Available This paper is concerned with the blow-up solutions of the critical Gross-Pitaevskii equation, which models the Bose-Einstein condensate. The existence and qualitative properties of the minimal blow-up solutions are obtained.

  7. Transition between extinction and blow-up in a generalized Fisher–KPP model

    Energy Technology Data Exchange (ETDEWEB)

    Hernández-Bermejo, Benito, E-mail: benito.hernandez@urjc.es [Departamento de Física, Universidad Rey Juan Carlos, Calle Tulipán S/N, 28933, Móstoles, Madrid (Spain); Sánchez-Valdés, Ariel [Departamento de Matemática Aplicada, Universidad Rey Juan Carlos, Calle Tulipán S/N, 28933, Móstoles, Madrid (Spain)

    2014-05-01

    Stationary solutions of the Fisher–KPP equation with general nonlinear diffusion and arbitrary reactional kinetic orders terms are characterized. Such stationary (separatrix-like) solutions disjoint the blow-up solutions from those showing extinction. In addition a criterion for general parameter values is presented, which allows determining the blow-up or vanishing character of the solutions.

  8. A formula for the Chern classes of symplectic blow-ups

    NARCIS (Netherlands)

    Geiges, H.; Pasquotto, F.

    2007-01-01

    It is shown that the formula for the Chern classes (in the Chow ring) of blow-ups of algebraic varieties, due to Porteous and Lascu-Scott, also holds (in the singular cohomology ring) for blow-ups of symplectic and complex manifolds. This was used by the second author in her solution of the

  9. Blow-Up of Solutions for a Class of Sixth Order Nonlinear Strongly Damped Wave Equation

    Directory of Open Access Journals (Sweden)

    Huafei Di

    2014-01-01

    Full Text Available We consider the blow-up phenomenon of sixth order nonlinear strongly damped wave equation. By using the concavity method, we prove a finite time blow-up result under assumptions on the nonlinear term and the initial data.

  10. Global existence and finite time blow-up for a parabolic system on hyperbolic space

    Science.gov (United States)

    Wu, Hui; Yang, Xiaoping

    2018-01-01

    In this paper, we study the global existence and finite time blow-up of positive solutions for a parabolic system on hyperbolic space. Using the heat semigroup and constructing subsolutions and supersolutions, we obtain the Fujita type results. In the case of a critical exponent, the critical exponent is not a blow-up exponent.

  11. Blow-up for a three dimensional Keller-Segel model with consumption of chemoattractant

    Science.gov (United States)

    Jiang, Jie; Wu, Hao; Zheng, Songmu

    2018-04-01

    We investigate blow-up properties for the initial-boundary value problem of a Keller-Segel model with consumption of chemoattractant when the spatial dimension is three. Through a kinetic reformulation of the Keller-Segel system, we first derive some higher-order estimates and obtain certain blow-up criteria for the local classical solutions. These blow-up criteria generalize the results in [4,5] from the whole space R3 to the case of bounded smooth domain Ω ⊂R3. Lower global blow-up estimate on ‖ n ‖ L∞ (Ω) is also obtained based on our higher-order estimates. Moreover, we prove local non-degeneracy for blow-up points.

  12. Parallel Computation of Persistent Homology using the Blowup Complex

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, Ryan [Stanford Univ., CA (United States); Morozov, Dmitriy [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2015-04-27

    We describe a parallel algorithm that computes persistent homology, an algebraic descriptor of a filtered topological space. Our algorithm is distinguished by operating on a spatial decomposition of the domain, as opposed to a decomposition with respect to the filtration. We rely on a classical construction, called the Mayer--Vietoris blowup complex, to glue global topological information about a space from its disjoint subsets. We introduce an efficient algorithm to perform this gluing operation, which may be of independent interest, and describe how to process the domain hierarchically. We report on a set of experiments that help assess the strengths and identify the limitations of our method.

  13. Perturbational blowup solutions to the compressible Euler equations with damping.

    Science.gov (United States)

    Cheung, Ka Luen

    2016-01-01

    The N-dimensional isentropic compressible Euler system with a damping term is one of the most fundamental equations in fluid dynamics. Since it does not have a general solution in a closed form for arbitrary well-posed initial value problems. Constructing exact solutions to the system is a useful way to obtain important information on the properties of its solutions. In this article, we construct two families of exact solutions for the one-dimensional isentropic compressible Euler equations with damping by the perturbational method. The two families of exact solutions found include the cases [Formula: see text] and [Formula: see text], where [Formula: see text] is the adiabatic constant. With analysis of the key ordinary differential equation, we show that the classes of solutions include both blowup type and global existence type when the parameters are suitably chosen. Moreover, in the blowup cases, we show that the singularities are of essential type in the sense that they cannot be smoothed by redefining values at the odd points. The two families of exact solutions obtained in this paper can be useful to study of related numerical methods and algorithms such as the finite difference method, the finite element method and the finite volume method that are applied by scientists to simulate the fluids for applications.

  14. Local-in-space blow-up criteria for a class of nonlinear dispersive wave equations

    Science.gov (United States)

    Novruzov, Emil

    2017-11-01

    This paper is concerned with blow-up phenomena for the nonlinear dispersive wave equation on the real line, ut -uxxt +[ f (u) ] x -[ f (u) ] xxx +[ g (u) + f″/(u) 2 ux2 ] x = 0 that includes the Camassa-Holm equation as well as the hyperelastic-rod wave equation (f (u) = ku2 / 2 and g (u) = (3 - k) u2 / 2) as special cases. We establish some a local-in-space blow-up criterion (i.e., a criterion involving only the properties of the data u0 in a neighborhood of a single point) simplifying and precising earlier blow-up criteria for this equation.

  15. Beam instabilities in race track microtrons

    International Nuclear Information System (INIS)

    Euteneuer, H.; Herminghaus, H.; Klein, R.

    1982-01-01

    Several limitations of the benefits of the race track microtron (RTM) as an economic cw electron accelerator are discussed. For beam blowup some final results of our investigations for the Mainz Microtron are given. The other two effects presented more generally are beam diffusion by imperfections of the optical elements of a RTM and the deterioration of transverse phase space by synchrotron radiation

  16. Blow-up Criteria of Classical Solutions of Three-Dimensional Compressible Magnetohydrodynamic Equations

    Science.gov (United States)

    Liu, Xin

    2018-03-01

    In this paper we consider the isentropic compressible magnetohydrodynamic equations in three space dimensions, and establish a blow-up criterion of classical solutions, which depends on the gradient of the velocity and magnetic field.

  17. Space dimension can prevent the blow-up of solutions for parabolic problems

    Directory of Open Access Journals (Sweden)

    Alkis S. Tersenov

    2007-11-01

    Full Text Available In the present paper, we investigate the preventive role of space dimension for semilinear parabolic problems. Conditions guaranteeing the absence of the blow-up of the solutions are formulated.

  18. A blow-up result for a viscoelastic system in $R^n

    Directory of Open Access Journals (Sweden)

    Salim A. Messaoudi

    2007-08-01

    Full Text Available In this paper we consider a coupled system of nonlinear viscoelastic equations. Under suitable conditions on the initial data and the relaxation functions, we prove a finite-time blow-up result.

  19. On lower bounds for possible blow-up solutions to the periodic Navier-Stokes equation

    International Nuclear Information System (INIS)

    Cortissoz, Jean C.; Montero, Julio A.; Pinilla, Carlos E.

    2014-01-01

    We show a new lower bound on the H .3/2 (T 3 ) norm of a possible blow-up solution to the Navier-Stokes equation, and also comment on the extension of this result to the whole space. This estimate can be seen as a natural limiting result for Leray's blow-up estimates in L p (R 3 ), 3 .5/2 (T 3 ), and give the corresponding extension to the case of the whole space

  20. Treatment of Orbital Roof Blow-Up Fracture Using a Superior Blepharoplasty Incision.

    Science.gov (United States)

    Matsuzaki, Kyoichi; Enomoto, Sayaka; Aoki, Tomoko

    2015-06-01

    In orbital roof blow-up fractures, reduction can be achieved easily using an approach from the anterior cranial fossa but the procedure is highly invasive. In contrast, an orbital approach using a superior blepharoplasty incision is minimally invasive. However, if bone fragments are adhered to the dura mater, there is a risk of dura mater injury when fragments are moved for reduction. In blow-in fractures, reduction is performed by pushing the bone fragments against the anterior cranial fossa. In contrast, the procedure is difficult for blow-up fractures because bone fragments must be pulled out into the orbit through the anterior cranial fossa. Orbital blow-up fractures are often associated with intracranial injuries and frequently treated by an approach from the anterior cranial fossa. There has not yet been a report that discusses whether reduction of bone fragments should be performed in blow-up fracture without intracranial injury. In this report, we describe two cases of orbital roof blow-up fracture that did not require treatment for intracranial injury and that were treated using an orbital approach. The treatment involved only the release of orbital fat entrapped between bone fragments and did not involve reduction. The treatment outcomes were good in both cases.

  1. Local solvability and solution blow-up of one-dimensional equations of the Yajima-Oikawa-Satsuma type

    Science.gov (United States)

    Panin, A. A.; Shlyapugin, G. I.

    2017-11-01

    We consider one-dimensional equations of the type of the Yajima-Oikawa-Satsuma ion acoustic wave equation and prove the local solvability. Using the test function method, we obtain sufficient conditions for solution blow-up and estimate the blow-up time.

  2. Blowup Phenomenon of Solutions for the IBVP of the Compressible Euler Equations in Spherical Symmetry.

    Science.gov (United States)

    Cheung, Ka Luen; Wong, Sen

    2016-01-01

    The blowup phenomenon of solutions is investigated for the initial-boundary value problem (IBVP) of the N-dimensional Euler equations with spherical symmetry. We first show that there are only trivial solutions when the velocity is of the form c(t)|x| (α-1) x + b(t)(x/|x|) for any value of α ≠ 1 or any positive integer N ≠ 1. Then, we show that blowup phenomenon occurs when α = N = 1 and [Formula: see text]. As a corollary, the blowup properties of solutions with velocity of the form [Formula: see text] are obtained. Our analysis includes both the isentropic case (γ > 1) and the isothermal case (γ = 1).

  3. Blow-up of solutions to the rotation b-family system modeling equatorial water waves

    Directory of Open Access Journals (Sweden)

    Min Zhu

    2018-03-01

    Full Text Available We consider the blow-up mechanism to the periodic generalized rotation b-family system (R-b-family system. This model can be derived from the f-plane governing equations for the geographical water waves with a constant underlying current in the equatorial water waves with effect of the Coriolis force. When b=2, it is a rotation two-component Camassa-Holm (R2CH system. We consider the periodic R2CH system when linear dispersion is absent (which model is called r2CH system and derive two finite-time blow-up results.

  4. The method of non-local transformations: Applications to blow-up problems

    Science.gov (United States)

    Polyanin, A. D.; Shingareva, I. K.

    2017-12-01

    The method for numerical integration of Cauchy problems for ODEs with blow-up solutions is described. It is based on introducing a new non-local variable that reduces a single nth-order ODE to a system of first-order coupled ODEs. This method leads to problems whose solutions are presented in parametric form and do not have blowing-up singular points; therefore the standard fixed-step numerical methods can be applied. The efficiency of the proposed method is illustrated with two test problems. It is shown that the first Painlevé equation with suitable initial conditions have non-monotonic blow-up solutions.

  5. Blow-up in nonlinear Schroedinger equations. I. A general review

    DEFF Research Database (Denmark)

    Juul Rasmussen, Jens; Rypdal, K.

    1986-01-01

    The general properties of a class of nonlinear Schroedinger equations: iut + p:∇∇u + f(|u|2)u = 0 are reviewed. Conditions for existence, uniqueness, and stability of solitary wave solutions are presented, along with conditions for blow-up and global existence for the Cauchy problem.......The general properties of a class of nonlinear Schroedinger equations: iut + p:∇∇u + f(|u|2)u = 0 are reviewed. Conditions for existence, uniqueness, and stability of solitary wave solutions are presented, along with conditions for blow-up and global existence for the Cauchy problem....

  6. Blow-Up Analysis for a Quasilinear Degenerate Parabolic Equation with Strongly Nonlinear Source

    Directory of Open Access Journals (Sweden)

    Pan Zheng

    2012-01-01

    Full Text Available We investigate the blow-up properties of the positive solution of the Cauchy problem for a quasilinear degenerate parabolic equation with strongly nonlinear source ut=div(|∇um|p−2∇ul+uq,  (x,t∈RN×(0,T, where N≥1, p>2 , and m, l,  q>1, and give a secondary critical exponent on the decay asymptotic behavior of an initial value at infinity for the existence and nonexistence of global solutions of the Cauchy problem. Moreover, under some suitable conditions we prove single-point blow-up for a large class of radial decreasing solutions.

  7. Blow-Up and Global Existence for a Quasilinear Parabolic System

    Directory of Open Access Journals (Sweden)

    Chunchen Wu

    2014-01-01

    Full Text Available The problem of solutions to a class of quasilinear coupling parabolic system was studied. By constructing weak upper-solutions and weak lower-solutions, we obtain the global existence and blow-up of solutions under appropriate conditions.

  8. Blow-up of solutions for the sixth-order thin film equation with ...

    Indian Academy of Sciences (India)

    Abstract. In this paper, a sixth-order parabolic thin film equation with the initial boundary condi- tion is considered. By using the improved energy estimate method and by constructing second-order elliptic problem, a blow-up result for certain solution with positive initial energy is established, which is an improve over the ...

  9. Exact, rotational, infinite energy, blowup solutions to the 3-dimensional Euler equations

    International Nuclear Information System (INIS)

    Yuen, Manwai

    2011-01-01

    In this Letter, we construct a new class of blowup or global solutions with elementary functions to the 3-dimensional compressible or incompressible Euler and Navier-Stokes equations. And the corresponding blowup or global solutions for the incompressible Euler and Naiver-Stokes equations are also given. Our constructed solutions are similar to the famous Arnold-Beltrami-Childress (ABC) flow. The obtained solutions with infinite energy can exhibit the interesting behaviors locally. Furthermore, due to divu → =0 for the solutions, the solutions also work for the 3-dimensional incompressible Euler and Navier-Stokes equations. -- Highlights: → We construct a new class of solutions to the 3D compressible or incompressible Euler and Navier-Stokes equations. → The constructed solutions are similar to the famous Arnold-Beltrami-Childress flow. → The solutions with infinite energy can exhibit the interesting behaviors locally.

  10. Blow-up analysis for a system of heat equations coupled through a nonlinear boundary condition

    DEFF Research Database (Denmark)

    Pedersen, M.; Lin, Zhigui

    2001-01-01

    Consider the system of heat equations uit - Δui = 0 (i = 1 , . . . , k, uk+i := u1) in Ω x (0, T) coupled through nonlinear boundary conditions ∂ui/∂η = up1i+1 on ∂Ω x [0, T). The upper and lower bounds of the blow-up rate is derived. © 2000 Elsevier Science Ltd. All rights reserved.......Consider the system of heat equations uit - Δui = 0 (i = 1 , . . . , k, uk+i := u1) in Ω x (0, T) coupled through nonlinear boundary conditions ∂ui/∂η = up1i+1 on ∂Ω x [0, T). The upper and lower bounds of the blow-up rate is derived. © 2000 Elsevier Science Ltd. All rights reserved....

  11. LHC MD 1087: Controlled Longitudinal Emittance Blow-up with Short Bunches

    CERN Document Server

    Timko, Helga; Esteban Muller, Juan; Jaussi, Michael; Lasheen, Alexandre; Shaposhnikova, Elena; CERN. Geneva. ATS Department

    2017-01-01

    The aim of the MD was to study the controlled longitudinal emittance blow-up applied during the ramp with bunches that are slightly shorter than operational. Earlier MDs in 2015 have shown that with a short target bunch length, the blow-up is less controlled and a bifurcation of bunch lengths occurs. The presented measurements show that the bifurcation is independent of the presence of the bunch length feedback, pointing towards an intensity-dependent phenomenon, originating from a synchrotron frequency shift with intensity. Accurate measurements of synchrotron frequency shift with intensity are presented as well. The measurements took place between 22nd August 2016, 19:00 and 23rd August 2016, 04:00.

  12. Blow-up analysis for a system of heat equations coupled through a nonlinear boundary condition

    DEFF Research Database (Denmark)

    Pedersen, M.; Lin, Zhigui

    2001-01-01

    Consider the system of heat equations uit - Δui = 0 (i = 1 , . . . , k, uk+i := u1) in Ω x (0, T) coupled through nonlinear boundary conditions ∂ui/∂η = up1i+1 on ∂Ω x [0, T). The upper and lower bounds of the blow-up rate is derived. © 2000 Elsevier Science Ltd. All rights reserved....

  13. Blow-up Estimates of the Positive Solution of a Parabolic System

    DEFF Research Database (Denmark)

    Pedersen, Michael; Zhigui, Lin

    1999-01-01

    This paper establishes the blowup estimates for the systems: $u_t-\\Delta u=0,$ $v_t-\\Delta v=0$ in $B_R\\times (0,T)$, $B_R\\subset\\Bbb R^n$, with the nonlinear boundary conditions $\\frac{\\partial u}{\\partial \\eta}=u^{m_1}v^{n_1}$ and $\\frac{\\partial v}{\\partial \\eta}=u^{m_2}v^{n_2}$ on $S_R\\times (0...

  14. Blow-up Estimates of the Positive Solution of a Parabolic System

    DEFF Research Database (Denmark)

    Pedersen, Michael; Zhigui, Lin

    2001-01-01

    This paper establishes the blow-up estimates for the systems u(t) - Deltau = 0, v(t) - Deltav = 0 in B-R x (0, T), B-R subset of R-n, with the nonlinear boundary conditions partial derivativeu/partial derivativen = u(m1)v(n1) and partial derivativev/partial derivativen = u(m2)v(n2) on S-R x (0, T...

  15. A note on Burgers' equation with time delay: Instability via finite-time blow-up

    International Nuclear Information System (INIS)

    Jordan, P.M.

    2008-01-01

    Burgers' equation with time delay is considered. Using the Cole-Hopf transformation, the exact solution of this nonlinear partial differential equation (PDE) is determined in the context of a (seemingly) well-posed initial-boundary value problem (IBVP) involving homogeneous Dirichlet data. The solution obtained, however, is shown to exhibit a delay-induced instability, suffering blow-up in finite-time

  16. Classification of minimal mass blow-up solutions for an L2 critical inhomogeneous NLS

    NARCIS (Netherlands)

    Combet, V.; Genoud, S.F.

    2016-01-01

    We establish the classification of minimal mass blow-up solutions of the L2 critical inhomogeneous nonlinear Schrödinger equation i?tu+?u+|x|?b|u|4?2bNu=0, thereby extending the celebrated result of Merle (Duke Math J 69(2):427–454, 1993) from the classic case b=0 to the case 0

  17. Some problems on non-linear semigroups and the blow-up of integral solutions

    International Nuclear Information System (INIS)

    Pavel, N.H.

    1983-07-01

    After some introductory remarks, this highly mathematical document considers a unifying approach in the theory of non-linear semigroups. Then a brief survey is given on blow-up of mild solutions from the semilinear case. Finally, the global behavior of solutions to non-linear evolution equations is addressed; it is found that classical results on the behavior of the maximal solution u as t up-arrow tsub(max) hold also for integral solutions

  18. Universal structure of blow-up in 1D conservation laws

    OpenAIRE

    Mailybaev, Alexei A.

    2011-01-01

    We discuss universality properties of blow-up of a classical (smooth) solutions of conservation laws in one space dimension. It is shown that the renormalized wave profile tends to a universal function, which is independent both of initial conditions and of the form of a conservation law. This property is explained in terms of the renormalization group theory. A solitary wave appears in logarithmic coordinates of the Fourier space as a counterpart of this universality. Universality is demonst...

  19. Beyond blow-up in excitatory integrate and fire neuronal networks: Refractory period and spontaneous activity.

    Science.gov (United States)

    Cáceres, María J; Perthame, Benoît

    2014-06-07

    The Network Noisy Leaky Integrate and Fire equation is among the simplest model allowing for a self-consistent description of neural networks and gives a rule to determine the probability to find a neuron at the potential v. However, its mathematical structure is still poorly understood and, concerning its solutions, very few results are available. In the midst of them, a recent result shows blow-up in finite time for fully excitatory networks. The intuitive explanation is that each firing neuron induces a discharge of the others; thus increases the activity and consequently the discharge rate of the full network. In order to better understand the details of the phenomena and show that the equation is more complex and fruitful than expected, we analyze further the model. We extend the finite time blow-up result to the case when neurons, after firing, enter a refractory state for a given period of time. We also show that spontaneous activity may occur when, additionally, randomness is included on the firing potential VF in regimes where blow-up occurs for a fixed value of VF. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Attempted density blowup in a freely cooling dilute granular gas: hydrodynamics versus molecular dynamics.

    Science.gov (United States)

    Puglisi, Andrea; Assaf, Michael; Fouxon, Itzhak; Meerson, Baruch

    2008-02-01

    It has been recently shown [I. Fouxon, Phys. Rev. E 75, 050301(R) (2007); I. Fouxon, Phys. Fluids 19, 093303 (2007)] that, in the framework of ideal granular hydrodynamics (IGHD), an initially smooth hydrodynamic flow of a granular gas can produce an infinite gas density in a finite time. Exact solutions that exhibit this property have been derived. Close to the singularity, the granular gas pressure is finite and almost constant. We report molecular dynamics (MD) simulations of a freely cooling gas of nearly elastically colliding hard disks, aimed at identifying the "attempted" density blowup regime. The initial conditions of the simulated flow mimic those of one particular solution of the IGHD equations that exhibits the density blowup. We measure the hydrodynamic fields in the MD simulations and compare them with predictions from the ideal theory. We find a remarkable quantitative agreement between the two over an extended time interval, proving the existence of the attempted blowup regime. As the attempted singularity is approached, the hydrodynamic fields, as observed in the MD simulations, deviate from the predictions of the ideal solution. To investigate the mechanism of breakdown of the ideal theory near the singularity, we extend the hydrodynamic theory by accounting separately for the gradient-dependent transport and for finite density corrections.

  1. On the blow-up problem for the axisymmetric 3D Euler equations

    International Nuclear Information System (INIS)

    Chae, Dongho

    2008-01-01

    In this paper we study the finite time blow-up problem for the axisymmetric 3D incompressible Euler equations with swirl. The evolution equations for the deformation tensor and the vorticity are reduced considerably in this case. Under the assumption of local minima for the pressure on the axis of symmetry with respect to the radial variations we show that the solution blows up in finite time. If we further assume that the second radial derivative vanishes on the axis, then the system reduces to the form of Constantin–Lax–Majda equations and can be integrated explicitly

  2. Global existence and blowup for free boundary problems of coupled reaction-diffusion systems

    Directory of Open Access Journals (Sweden)

    Jianping Sun

    2014-05-01

    Full Text Available This article concerns a free boundary problem for a reaction-diffusion system modeling the cooperative interaction of two diffusion biological species in one space dimension. First we show the existence and uniqueness of a local classical solution, then we study the asymptotic behavior of the free boundary problem. Our results show that the free boundary problem admits a global solution if the inter-specific competitions are strong, while, if the inter-specific competitions are weak, there exist the blowup solution and a global fast solution.

  3. Asymptotic analysis of reaction-diffusion-advection problems: Fronts with periodic motion and blow-up

    Science.gov (United States)

    Nefedov, Nikolay

    2017-02-01

    This is an extended variant of the paper presented at MURPHYS-HSFS 2016 conference in Barcelona. We discuss further development of the asymptotic method of differential inequalities to investigate existence and stability of sharp internal layers (fronts) for nonlinear singularly perturbed periodic parabolic problems and initial boundary value problems with blow-up of fronts for reaction-diffusion-advection equations. In particular, we consider periodic solutions with internal layer in the case of balanced reaction. For the initial boundary value problems we prove the existence of fronts and give their asymptotic approximation including the new case of blowing-up fronts. This case we illustrate by the generalised Burgers equation.

  4. On blow-up of solutions of the Kuramoto-Sivashinsky equation

    International Nuclear Information System (INIS)

    Pokhozhaev, S I

    2008-01-01

    The problem of the absence of global solutions of initial-boundary value problems for the Kuramoto-Sivashinsky equation is considered. Sufficient conditions for the absence of global solutions of the problems under consideration are obtained both for bounded and unbounded domains. These conditions imply a priori the blow-up of the solution of the corresponding initial-boundary value problem. The proof uses a generalization of the method of non-linear capacity based on the choice of asymptotically optimal test functions. Bibliography: 20 titles.

  5. Critical Blow-Up and Global Existence for Discrete Nonlinear p-Laplacian Parabolic Equations

    Directory of Open Access Journals (Sweden)

    Soon-Yeong Chung

    2014-01-01

    Full Text Available The goal of this paper is to investigate the blow-up and the global existence of the solutions to the discrete p-Laplacian parabolic equation utx,t=Δp,wux,t+λux,tp-2ux,t, x,t∈S×0,∞, ux,t=0, x,t∈∂S×0,∞, ux,0=u0, depending on the parameters p>1 and λ>0. Besides, we provide several types of the comparison principles to this equation, which play a key role in the proof of the main theorems. In addition, we finally give some numerical examples which exploit the main results.

  6. Construction of a Blow-Up Solution for the Complex Ginzburg-Landau Equation in a Critical Case

    Science.gov (United States)

    Nouaili, Nejla; Zaag, Hatem

    2017-12-01

    We construct a solution for the Complex Ginzburg-Landau equation in a critical case which blows up in finite time T only at one blow-up point. We also give a sharp description of its profile. The proof relies on the reduction of the problem to a finite dimensional one, and the use of index theory to conclude. The interpretation of the parameters of the finite dimension problem in terms of the blow-up point and time allows us to prove the stability of the constructed solution.

  7. Longitudinal emittance blow-up and production of future LHC beams

    CERN Document Server

    Albright, S; Shaposhnikova, E

    2017-01-01

    During Long Shutdown 2 the RF systems of the PSB willbe replaced with broadband Finemet systems, there will alsobe an energy increase and many other modifications. Thisnote summarises studies that were done to investigate how tomeet the emittance requirements for the LIU-PSB baselineand a possible use of the broadband cavities to improve thecapture process.The LIU-PSB baseline requires longitudinal emittanceblow-up to 3 eVs with 205 ns bunch length at extraction. Thecurrent ferrite RF systems were used, with phase modulationof a high harmonic, to produce 2.8 eVs bunches with 220ns bunch length, as this is the largest that can currentlybe transferred to the PS. Larger emittances were possible,demonstrating the ability to reach the LIU-PSB baseline inthe future, which is confirmed in simulation.The broadband impedance of the Finemet was exploitedto allow RF voltage to be supplied on three harmonics (h=1,h=2, h=3), as opposed to the usual 2. For high intensitybeams this lead to an improved capture efficiency for...

  8. Blow-up in multidimensional aggregation equations with mildly singular interaction kernels

    International Nuclear Information System (INIS)

    Bertozzi, Andrea L; Laurent, Thomas; Carrillo, José A

    2009-01-01

    We consider the multidimensional aggregation equation u t − ∇· (u∇K * u) = 0 in which the radially symmetric attractive interaction kernel has a mild singularity at the origin (Lipschitz or better). In the case of bounded initial data, finite time singularity has been proved for kernels with a Lipschitz point at the origin (Bertozzi and Laurent 2007 Commun. Math. Sci. 274 717–35), whereas for C 2 kernels there is no finite-time blow-up. We prove, under mild monotonicity assumptions on the kernel K, that the Osgood condition for well-posedness of the ODE characteristics determines global in time well-posedness of the PDE with compactly supported bounded nonnegative initial data. When the Osgood condition is violated, we present a new proof of finite time blow-up that extends previous results, requiring radially symmetric data, to general bounded, compactly supported nonnegative initial data without symmetry. We also present a new analysis of radially symmetric solutions under less strict monotonicity conditions. Finally, we conclude with a discussion of similarity solutions for the case K(x) = |x| and some open problems

  9. Finite time blow-up of solutions for a nonlinear system of fractional differential equations

    Directory of Open Access Journals (Sweden)

    Abdelaziz Mennouni

    2017-06-01

    Full Text Available In this article we study the blow-up in finite time of solutions for the Cauchy problem of fractional ordinary equations $$\\displaylines{ u_{t} +a_1\\,^{c}D_{0_{+}}^{\\alpha_1} u +a_2\\,^{c}D_{0_{+}}^{\\alpha_2} u+\\dots +a_{n}\\,^{c}D_{0_{+}}^{\\alpha_n} u =\\int_0^{t} \\frac{(t-s^{-\\gamma_1}}{ \\Gamma(1-\\gamma_1 }f(u(s,v(sds,\\cr v_{t} +b_1\\,^{c}D_{0_{+}}^{\\beta_1} v+ b_2\\,^{c}D_{0_{+}}^{\\beta_2} v+\\dots +b_{n}\\,^{c}D_{0_{+}}^{\\beta_n} v = \\int_0^{t} \\frac{(t-s^{-\\gamma_2}}{ \\Gamma(1-\\gamma_2 }g(u(s,v(sds, }$$ for t>0, where the derivatives are Caputo fractional derivatives of order $\\alpha_i, \\beta_i$, and f and g are two continuously differentiable functions with polynomial growth. First, we prove the existence and uniqueness of local solutions for the above system supplemented with initial conditions, then we establish that they blow-up in finite time.

  10. Brezis-Gallouet-Wainger Type Inequalities and Blow-Up Criteria for Navier-Stokes Equations in Unbounded Domains

    Science.gov (United States)

    Nakao, Kohei; Taniuchi, Yasushi

    2017-12-01

    We shall find the weakest norm that satisfies the Brezis-Gallouet-Wainger type inequality, under some conditions. As an application of the Brezis-Gallouet-Wainger type inequality, we shall establish Beale-Kato-Majda type blow-up criteria of smooth solutions to the 3-D Navier-Stokes equations in unbounded domains.

  11. Blow-up results for systems of nonlinear Klein-Gordon equations with arbitrary positive initial energy

    Directory of Open Access Journals (Sweden)

    Shun-Tang Wu

    2012-06-01

    Full Text Available The initial boundary value problem for a system of nonlinear Klein-Gordon equations in a bounded domain is considered. We prove the existence of local solutions by using a successive approximation method. Then, we show blow-up results with arbitrary positive initial energy by a concavity method. Also estimates for the lifespan of solutions are given.

  12. Criteria on global boundedness versus finite time blow-up to a two-species chemotaxis system with two chemicals

    Science.gov (United States)

    Yu, Hao; Wang, Wei; Zheng, Sining

    2018-02-01

    This paper considers the two-species chemotaxis system with two chemicals in a smooth bounded domain Ω\\subset{R}2 , subject to the non-flux boundary condition, and χ, ξ, α, β, γ, δ>0 . We obtain a blow-up criterion that if m_1m_2-2π(\\frac{m_1}χβ+\\frac{m_2}ξδ)>0 , then there exist finite time blow-up solutions to the system with m_1:=\\int_Ω u_0(x)dx and m_2:=\\int_Ω w_0(x)dx . When χ=ξ= β=δ=1 , the blow-up criterion becomes m_1m_2-2π(m_1+m_2)>0 , and the global boundedness of solutions is furthermore established with α=γ=1 under the condition that \\max\\{m_1, m_2\\}current results for finite time blow-up with \\min\\{m_1, m_2\\}>4π and global boundedness with \\max\\{m_1, m_2\\}Education Department grant (LYB201601) and the Fundamental Research Funds for the Central Universities (DUT16LK24).

  13. Evolution PDEs with nonstandard growth conditions existence, uniqueness, localization, blow-up

    CERN Document Server

    Antontsev, Stanislav

    2015-01-01

    This monograph offers the reader a treatment of the theory of evolution PDEs with nonstandard growth conditions. This class includes parabolic and hyperbolic equations with variable or anisotropic nonlinear structure. We develop methods for the study of such equations and present a detailed account of recent results. An overview of other approaches to the study of PDEs of this kind is provided. The presentation is focused on the issues of existence and uniqueness of solutions in appropriate function spaces, and on the study of the specific qualitative properties of solutions, such as localization in space and time, extinction in a finite time and blow-up, or nonexistence of global in time solutions. Special attention is paid to the study of the properties intrinsic to solutions of equations with nonstandard growth.

  14. Finite-time blow-up in a quasilinear system of chemotaxis

    Science.gov (United States)

    Cieślak, Tomasz; Winkler, Michael

    2008-05-01

    We consider an elliptic-parabolic system of the Keller-Segel type which involves nonlinear diffusion. We find a critical exponent of the nonlinearity in the diffusion, measuring the strength of diffusion at points of high (population) densities, which distinguishes between finite-time blow-up and global-in-time existence of uniformly bounded solutions. This critical exponent depends on the space dimension n >= 1, where apart from the physically relevant cases n = 2 and n = 3 also the result obtained in the one-dimensional setting might be of mathematical interest: here, namely, finite-time explosion of solutions occurs although the Lyapunov functional associated with the system is bounded from below. Additionally this one-dimensional case is an example to show that L∞ estimates of solutions to non-uniformly parabolic drift-diffusion equations cannot be expected even when boundedness of the gradient of the drift term is presupposed.

  15. Blowup for biharmonic Schrödinger equation with critical nonlinearity

    Science.gov (United States)

    Phan, Thanh Viet

    2018-04-01

    We consider the minimizers for the biharmonic nonlinear Schrödinger functional E_a(u)=\\int \\limits _{R^d} |Δ u(x)|^2 dx + \\int \\limits _{R^d} V(x) |u(x)|^2 dx - a \\int \\limits _{R^d} |u(x)|q dx with the mass constraint \\int |u|^2=1. We focus on the special power q=2(1+4/d), which makes the nonlinear term \\int |u|^q scales similarly to the biharmonic term \\int |Δ u|^2. Our main results are the existence and blowup behavior of the minimizers when a tends to a critical value a^*, which is the optimal constant in a Gagliardo-Nirenberg interpolation inequality.

  16. Regularizations of two-fold bifurcations in planar piecewise smooth systems using blowup

    DEFF Research Database (Denmark)

    Kristiansen, Kristian Uldall; Hogan, S. J.

    2015-01-01

    We use blowup to study the regularization of codimension one two-fold singularities in planar piecewise smooth (PWS) dynamical systems. We focus on singular canards, pseudo-equlibria and limit cycles that can occur in the PWS system. Using the regularization of Sotomayor and Teixeira [30], we show...... rigorously how singular canards can persist and how the bifurcation of pseudo-equilibria is related to bifurcations of equilibria in the regularized system. We also show that PWS limit cycles are connected to Hopf bifurcations of the regularization. In addition, we show how regularization can create another...... as locally unique families of periodic orbits of the regularization and connect them, when possible, to limit cycles of the PWS system. We illustrate our analysis with numerical simulations and show how the regularized system can undergo a canard explosion phenomenon...

  17. Damping of coherent oscillations in intense ion beams

    International Nuclear Information System (INIS)

    Karpov, Ivan

    2017-01-01

    Transverse decoherence of a displaced ion bunch is an important phenomenon in synchrotrons and storage rings. An offset can be caused by an injection error after the bunch-to-bucket transfer between synchrotrons or by an externally generated kick. Decoherence results in a transverse emittance blowup, which can cause particle losses and a beam quality degradation. To prevent the beam blowup, a transverse feedback system (TFS) can be used. The damping time should be shorter than the characteristic decoherence time, which can be strongly affected by the interplay of different intensity effects (e.g., space charge and impedances). This thesis describes the development of the analytical models that explain decoherence and emittance growth with chromaticity, space charge, and image charges within the first synchrotron period. The pulsed response function including intensity effects was derived from the model for beam transfer functions. For a coasting beam, the two- dimensional model shows that space charge slows down and above intensity threshold suppresses decoherence. These predictions were confirmed by particle tracking simulations with self-consistent space charge fields. Additionally, halo buildup and losses during decoherence were observed in simulations. These effects were successfully interpreted using a non self-consistent particle-core model. The two-dimensional model was extended to the bunched beams. The simulation results reproduce the analytical predictions. The intensity threshold of decoherence suppression is higher in comparison to a coasting beam, image charges can restore decoherence. In the present work dedicated experiments were performed in the SIS18 synchrotron at GSI Darmstadt and the results were compared with simulations and analytical predictions. The contribution of nonlinearities and image charges is negligible while chromaticity and space charge dominate decoherence. To study the damping efficiency of TFS, a comprehensive TFS module was

  18. Blowup phenomena for the compressible euler and euler-poisson equations with initial functional conditions.

    Science.gov (United States)

    Wong, Sen; Yuen, Manwai

    2014-01-01

    We study, in the radial symmetric case, the finite time life span of the compressible Euler or Euler-Poisson equations in R (N) . For time t ≥ 0, we can define a functional H(t) associated with the solution of the equations and some testing function f. When the pressure function P of the governing equations is of the form P = Kρ (γ) , where ρ is the density function, K is a constant, and γ > 1, we can show that the nontrivial C (1) solutions with nonslip boundary condition will blow up in finite time if H(0) satisfies some initial functional conditions defined by the integrals of f. Examples of the testing functions include r (N-1)ln(r + 1), r (N-1) e (r) , r (N-1)(r (3) - 3r (2) + 3r + ε), r (N-1)sin((π/2)(r/R)), and r (N-1)sinh r. The corresponding blowup result for the 1-dimensional nonradial symmetric case is also given.

  19. Characterization of a nondestructive beam profile monitor using luminescent emission

    Directory of Open Access Journals (Sweden)

    A. Variola

    2007-12-01

    Full Text Available The LHC (large hadron collider [LHC study group: LHC. The large hadron collider conceptual design; CERN/AC/95-05] is the future p-p collider under construction at CERN, Geneva. Over a circumference of 26.7 km a set of cryogenic dipoles and rf cavities will store and accelerate proton and ion beams up to energies of the order of 7 TeV. Injection in LHC will be performed by the CERN complex of accelerators, starting from the source and passing through the linac, the four booster rings, the proton synchrotron (PS, and super proton synchrotron (SPS accelerators. One of the main constraints on LHC performance is emittance preservation along the whole chain of CERN accelerators. The accepted relative normalized emittance blowup after filamentation is ±7%. To monitor the beam and the emittance blowup process, a study of different prototypes of nonintercepting beam profile monitors has been performed. In this context a monitor using the luminescent emission of gases excited by ultrarelativistic protons (450 GeV was developed and tested in the SPS ring. The results of beam size measurements and their evolution as a function of the machine parameters are presented. The image quality and resolution attainable in the LHC case have been assessed. A first full characterization of the luminescence cross section, spectrum, decay time, and afterglow effect for an ultrarelativistic proton beam is provided. Some significant results are also provided for lead ion beams.

  20. LHC Damper Beam commissioning in 2010

    CERN Document Server

    Höfle, W; Schokker, M; Valuch, D

    2011-01-01

    The LHC transverse dampers were commissioned in 2010 with beam and their use at injection energy of 450 GeV, during the ramp and in collisions at 3.5 TeV for Physics has become part of the standard operations pro- cedure. The system proved important to limit emittance blow-up at injection and to maintain smaller than nominal emittances throughout the accelerating cycle. We describe the commissioning of the system step-by-step as done in 2010 and summarize its performance as achieved for pro- ton as well as ion beams in 2010. Although its principle function is to keep transverse oscillations under control, the system has also been used as an exciter for abort gap clean- ing and tune measurement. The dedicated beam position measurement system with its low noise properties provides additional possibilities for diagnostics.

  1. MD 382: Beam Transfer Function and diffusion mechanisms

    CERN Document Server

    Tambasco, Claudia; Buffat, Xavier; Crouch, Matthew; Pieloni, Tatiana; Boccardi, Andrea; Fuchsberger, Kajetan; Gasior, Marek; Kotzian, Gerd; Lefevre, Thibaut; Pojer, Mirko; Salvachua Ferrando, Belen Maria; Solfaroli Camillocci, Matteo; Giachino, Rossano; CERN. Geneva. ATS Department

    2016-01-01

    The Beam Transfer Function (BTF) measurements have been previously tested in the LHC during MD block 1 and 2. Different machine configurations (i.e. energy, beam intensity, emittance etc...) have been tested to determine a safe set-up (excitation amplitude) of the system to be completely transparent to the beam (no emittance blow-up neither losses). The aim of this experiment in MD block 3 was to characterize the Stability Diagram (SD) in the presence of diffusion mechanisms induced by excited resonances due to beam-beam long range and Landau octupole interplay. During the experiment, BTF measurements have been acquired at flat top for different settings of Landau octupole current, different chromaticity values and transverse feedback gains. In this note the description of the experiment is presented together with some preliminary results.

  2. Condition for a single bunch high frequency fast blow-up

    International Nuclear Information System (INIS)

    Wang, J.M.; Pellegrini, C.

    1980-01-01

    We study the longitudinal stability of a single particle bunch in a storage ring using Vlasov equation. We show that the Vlasov equation has solutions corresponding to a fast, microwave instability if a condition on the beam current, qualitatively similar to the stability condition for a coasting beam, is satisfied. This condition can be used to define a threshold current, and to discuss its dependence on the longitudinal coupling impedance

  3. High Intensity Beam Issues in the CERN Proton Synchrotron

    CERN Document Server

    Aumon, Sandra; Rivkin, Leonid

    This PhD work is about limitations of high intensity proton beams observed in the CERN Proton Synchrotron (PS) and, in particular, about issues at injection and transition energies. With its 53 years, the CERN PS would have to operate beyond the limit of its performance to match the future requirements. Beam instabilities driven by transverse impedance and aperture restrictions are important issues for the operation and for the High-Luminosity LHC upgrade which foresees an intensity increase delivered by the injectors. The main subject of the thesis concerns the study of a fast transverse instability occurring at transition energy. The proton beams crossing this energy range are particularly sensitive to wake forces because of the slow synchrotron motion. This instability can cause a strong vertical emittance blow-up and severe losses in less than a synchrotron period. Experimental observations show that the particles at the peak density of the beam longitudinal distribution oscillate in the vertical plane du...

  4. Characterization of a nondestructive beam profile monitor using luminescent emission

    CERN Document Server

    Variola, A; Ferioli, G

    2007-01-01

    The LHC (large hadron collider) [LHC study group: LHC. The large hadron collider conceptual design; CERN/AC/95-05] is the future p-p collider under construction at CERN, Geneva. Over a circumference of 26.7 km a set of cryogenic dipoles and rf cavities will store and accelerate proton and ion beams up to energies of the order of 7 TeV. Injection in LHC will be performed by the CERN complex of accelerators, starting from the source and passing through the linac, the four booster rings, the proton synchrotron (PS), and super proton synchrotron (SPS) accelerators. One of the main constraints on LHC performance is emittance preservation along the whole chain of CERN accelerators. The accepted relative normalized emittance blowup after filamentation is ±7%. To monitor the beam and the emittance blowup process, a study of different prototypes of nonintercepting beam profile monitors has been performed. In this context a monitor using the luminescent emission of gases excited by ultrarelativistic protons (450 GeV) ...

  5. Conceptual designs of beam choppers for RFQ linacs

    International Nuclear Information System (INIS)

    Nath, S.; Stevens, S.R. Jr.; Wangler, T.P.

    1995-01-01

    A design study at Los Alamos of a linac/accumulator ring facility for a pulsed neutron spallation source calls for an H - beam with a chopped structure of approximately 200-ns beam-free segments every 600-ns. The required angular impulse can easily be provided with existing pulse power technology and traveling wave structures with a transverse electric field similar to those now available. The deflected beam is then restored by suitable collimation. Chopping is relatively easily done at sufficiently low energies, where the beam is easily deflected, and beam powers are not too large. However, the energy should be high enough so that the space-charge blow-up of the beam can be controlled with adequate focusing. LAMPF presently uses a traveling-wave beam chopper at 750 keV, before injection into the drift tube linac (DTL). In the new linac designs, a radiofrequency quadrupole (RFQ) linac would typically bunch and accelerate the high intensity H - beam from 100 keV to 7 MeV. In this paper, the authors present concepts for beam-chopper systems both before and after the RFQ. The beam-optics designs are presented, together with numerical simulation results

  6. Beam-beam effects in high energy e+e- storage rings: resonant amplification of vertical dimensions for flat beams

    International Nuclear Information System (INIS)

    Bambade, P.

    1984-06-01

    In this thesis, we present a phenomenological study of the beam-beam effect in e + e - storage rings. We are in particular interested in the blow-up of the vertical dimension observed in this kind of accelerator. A detailed analysis of the electromagnetic field generated by the very flat bunches stored, and seen by the counter-rotating particles shows that two-dimensional non-linear resonances, which couple vertical and horizontal betatron oscillations, play a very important role. Moreover, the ''weak beam-strong beam'' approximation holds rather well in the case of very flat bunches. Perturbative analysis enables us to predict the effects from the strongest coupling resonance: 20sub(x)-20sub(y) = integer. We find that mainly the tails of the vertical distribution are affected, and we give a criterion concerning the optimal distance to this resonance in the case of a storage ring such as LEP. Finally, the results and in particular the validity of the single resonance approximation are checked through a numerical simulation [fr

  7. Eroding dipoles and vorticity growth for Euler flows in {{{R}}}^{3}: the hairpin geometry as a model for finite-time blowup

    Science.gov (United States)

    Childress, Stephen; Gilbert, Andrew D.

    2018-02-01

    A theory of an eroding ‘hairpin’ vortex dipole structure in three-dimensions is developed, extending our previous study of an axisymmetric eroding dipole without swirl. The axisymmetric toroidal dipole was found to lead to maximal growth of vorticity, as {t}4/3. The hairpin is here similarly proposed as a model to produce large ‘self-stretching’ of vorticity, with the possibility of finite-time blow-up. We derive a system of partial differential equations of ‘generalized’ form, involving contour averaging of a locally two-dimensional Euler flow. We do not attempt here to solve the system exactly, but point out that non-existence of physically acceptable solutions would most probably be a result of the axial flow. Because of the axial flow the vorticity distribution within the dipole eddies is no longer of the simple Sadovskii type (vorticity constant over a cross-section) obtained in the axisymmetric problem. Thus the solution of the system depends upon the existence of a larger class of propagating two-dimensional dipoles. The hairpin model is obtained by formal asymptotic analysis. As in the axisymmetric problem a local transformation to ‘shrinking’ coordinates is introduced, but now in a self-similar form appropriate to the study of a possible finite-time singularity. We discuss some properties of the model, including a study of the helicity and a first step in iterating toward a solution from the Sadovskii structure. We also present examples of two-dimensional propagating dipoles not previously studied, which have a vorticity profile consistent with our model. Although no rigorous results can be given, and analysis of the system is only partial, the formal calculations are consistent with the possibility of a finite time blowup of vorticity at a point of vanishing circulation of the dipole eddies, but depending upon the existence of the necessary two-dimensional propagating dipole. Our results also suggest that conservation of kinetic energy as

  8. MD1228: Validation of Single Bunch Stability Threshold & MD1751: Instability Studies with a Single Beam

    CERN Document Server

    Carver, Lee Robert; Biancacci, Nicolo; Buffat, Xavier; Iadarola, Giovanni; Lasocha, Kacper; Li, Kevin Shing Bruce; Levens, Tom; Metral, Elias; Salvant, Benoit; Tambasco, Claudia; CERN. Geneva. ATS Department

    2017-01-01

    Instabilities were being routinely observed in B1V during ADJUST. The timing of the instabilities has been localised to shortly after the TOTEM bump has been implemented. The result is emittance blowup which can negatively effect the luminosity output of the fill. This MD aimed to rule out possible sources of the instability (i.e. beam-beam effects or electron cloud) by only taking one single beam to 6.5TeV and going through the full machine cycle. After the implementation of the TOTEM bump, a reduction of the octupole current was performed in order to determine if there was a discrepancy in the threshold between simulations and measurement. As a precursor, the results of the End of Fill MD: Validation of Single Bunch Stability Threshold will also be described.

  9. A fast wire scanner, used to measure the transverse density distribution of beams circulating in an accelerator or storage ring.

    CERN Multimedia

    Maximilien Brice

    2002-01-01

    Fast wire scanners are used to measure the transverse density distribution of beams circulating in an accelerator or storage ring. In order to minimize blow-up of the beam through multiple Coulomb scattering, the wires are very thin (in the version shown here it is actually a twisted strand of carbon fibres with a total diameter of about 25 microns) and are swept through the beam at high speed (a linear motor, not mounted here, accelerates the wires to up to 20 m/s). One measures either the secondary emission current from the wire, or the signal from a scintillator/photomultiplier combination downstream from the wire scanner receiving the shower from nuclear reactions of beam particles with the wire nuclei. There are four such fast wire scanners in the 26 GeV PS and eight in the 1.4 GeV Booster.

  10. Controlling multibunch beam breakup in TeV linear colliders

    International Nuclear Information System (INIS)

    Thompson, K.A.; Ruth, R.D.

    1989-01-01

    To obtain luminosities near 10 34 cm/sup /minus/2/sec/sup /minus/1/ in a TeV linear collider, it will probably be essential to accelerate many bunches per RF fill in order to increase the energy transfer efficiency. In this paper we study the transverse dynamics of multiple bunches in a linac, and we examine the effects of several methods of controlling the beam blow-up that would otherwise be induced by transverse dipole wake fields. The methods we study are: damping the transverse modes, adjusting the frequency of the dominant transverse modes so that bunches may be placed near zero-crossings of the transverse wake, and bunch-to-bunch variation of the transverse focusing. We study the utility of these cures in the main linacs of an example of a TeV collider. 16 refs., 4 figs., 2 tabs

  11. The δf algorithm for beam dynamics

    International Nuclear Information System (INIS)

    Koga, J.; Tajima, T.

    1993-05-01

    An algorithm is developed to study particle dynamics of beams including collective interaction with high accuracy and low noise. Particle dynamics with collective interactions is treated through particle simulation, where the main or average distribution f 0 and the deviation away from it δf are separately followed. The main distribution f 0 is handled by an analytic equilibrium solution and the perturbation away from it δf is followed by the method of characteristics. We call this the δf algorithm. We specifically model a synchrotron collider which includes the collision section where collective effects of collisions are simulated by this δf algorithm and the rest of the collider where single particle dynamics are treated by simple harmonic transport. The most important target of this simulation is to understand and predict the long-time behavior of the beam luminosity and lifetime. The δf method allows the study the effect of small perturbations over long timescales on beam lifetime by eliminating the numerical noise problem inherent in Particle-in-Cell techniques. In the δf code using the reference parameters of the SSC (Superconducting Super Collider), beam blow-up near resonances and oscillations in the tune shift, Δν, far from resonances are observed. In studying long timescale particle diffusion in the phase space of the beams away from resonances, the δf code performance is compared with a tracking code which does not incorporate collective interaction

  12. Longitudinal beam instabilities in a double RF system

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00229208; Gazis, Evangelos

    Operation with a double RF system is essential for many accelerators in order to increase beam stability, to change the bunch shape or to perform various RF manipulations. This is also the case for the operation of the CERN SPS as the LHC proton injector, where in addition to the main RF system, a fourth harmonic RF system is used in bunch shortening mode in order to increase the synchrotron frequency spread inside the bunch and thus to enhance Landau damping of the collective instabilities. In fact the double RF system operation in the SPS is one of the essential means, together with the controlled longitudinal emittance blow-up to significantly increase the longitudinal instability thresholds (single and multi-bunch) and deliver a good quality beam for the LHC. However, for the HiLumi-LHC (HL-LHC) and LHC injector upgrade (LIU) projects higher beam intensities are required. After all upgrades are in place, the main performance limitations of the LHC injector complex are beam instabilities and high intensity...

  13. Coherent beam-beam effects

    International Nuclear Information System (INIS)

    Chao, A.W.

    1992-01-01

    There are two physical pictures that describe the beam-beam interaction in a storage ring collider: The weak-strong and the strong-strong pictures. Both pictures play a role in determining the beam-beam behavior. This review addresses only the strong-strong picture. The corresponding beam dynamical effects are referred to as the coherent beam-beam effects. Some basic knowledge of the weak-strong picture is assumed. To be specific, two beams of opposite charges are considered. (orig.)

  14. Pinched Ion Beam Transport in the Target Chamber

    Science.gov (United States)

    Rosenbluth, M.; Lee, E. P.; Briggs, R. J.

    2000-10-01

    Ion beam pulses for fusion reactors have a very high charge per unit length and may carry a high current. In order to avoid thermal blowup and focus to a small spot, it is required to be charge neutral and desirable to have a pinching magnetic field. This requires that the neutralizing electrons flow relative to the ions, and of course the pinch behavior depends on the return current path. Since the electrons have small gyroradii a fluid, charge neutral model is adopted. After the pulse has been well detached from the chamber entrance hole and is distant from all emitting surfaces fields, we look for a steady-state solution in the beam frame with electrons recirculating. We find the conditions for such "plasmoid" solutions, indicating the desirability of shaping the radial profile and find that while the outer part of the beam pulse is blown out, the core may be reasonably well pinch-confined. The effects of interactions with background gas and plasma are discussed. We plan to study possible instabilities-kink, sausage, Rayleigh-Taylor and filamentation.

  15. Superresolution beams

    CSIR Research Space (South Africa)

    Ngcobo, S

    2011-11-01

    Full Text Available zones capable of introducing a phase shift of zero or p on the alternately out of phase rings of the TEMp0 beams into a unified phase and then focusing the rectified beam to generate a high resolution beam which has a Gaussian beam intensity distribution...

  16. Beam-beam and impedance

    CERN Document Server

    White, S.

    2014-07-17

    As two counter-rotating beams interact they can give rise to coherent dipole modes. Under the influence of impedance these coherent beam-beam modes can couple to higher order head-tail modes and lead to strong instabilities. A fully self-consistent approach including beam-beam and impedance was used to characterize this new coupled mode instability and study possible cures such as a transverse damper and high chromaticity.

  17. Transfer line scattering model of therapeutic hadron beams and applications to nozzle and gantry optimization

    Directory of Open Access Journals (Sweden)

    M. Palm

    2013-01-01

    Full Text Available The field of hadron therapy is growing rapidly with several facilities currently being planned, under construction or in commissioning worldwide. In the “active scanning” irradiation technique, the target is irradiated using a narrow pencil beam that is scanned transversally over the target while the penetration depth is altered with the beam energy. Together, the target dose can thereby be conformed in all three dimensions to the shape of the tumor. For applications where a sharp lateral beam penumbra is required in order to spare critical organs from unwanted dose, beam size blowup due to scattering in on-line beam diagnostic monitors, air gaps and passive elements like the ripple filter must be minimized. This paper presents a model for transverse scattering of therapeutic hadron beams along arbitrary multislab geometries. The conventional scattering formulation, which is only applicable to a drift space, is extended to not only take beam optics into account, but also non-Gaussian transverse beam profiles which are typically obtained from the slow resonant extraction from a synchrotron. This work has been carried out during the design phase of the beam delivery system for MedAustron, an Austrian hadron therapy facility with first patient treatment planned for the end of 2015. Irradiation will be performed using active scanning with proton and carbon ion beams. As a direct application of the scattering model, design choices for the MedAustron proton gantry and treatment nozzles are evaluated with respect to the transverse beam profile at the focal point; in air and at the Bragg peak.

  18. Beam cooling

    OpenAIRE

    Danared, H

    2006-01-01

    Beam cooling is the technique of reducing the momentum spread and increasing the phase-space density of stored particle beams. This paper gives an introduction to beam cooling and Liouville’s theorem, and then it describes the three methods of active beam cooling that have been proven to work so far, namely electron cooling, stochastic cooling, and laser cooling. Ionization cooling is also mentioned briefly.

  19. Molecular beams

    International Nuclear Information System (INIS)

    Pendelbury, J.M.; Smith, K.F.

    1987-01-01

    Studies with directed collision-free beams of particles continue to play an important role in the development of modern physics and chemistry. The deflections suffered by such beams as they pass through electric and magnetic fields or laser radiation provide some of the most direct information about the individual constituents of the beam; the scattering observed when two beams intersect yields important data about the intermolecular forces responsible for the scattering. (author)

  20. Longitudinal emittance reduction in LEIR of ion beams for LHC

    CERN Document Server

    Angoletta, M E; Findlay, A; Hancock, S; Manglunki, D

    2014-01-01

    For the 2013 LHC ion run the anticipated request for batches from the PS Complex comprising four ion bunches spaced by 100 ns was changed to batches of two bunches spaced by 200 ns. This modified demand was met by suppressing a splitting step in the PS machine, but with the consequence of halving the longitudinal emittance required from LEIR. Thus NOMINAL Pb54+ beams from LEIR had to be delivered inside ~9 eVs to provide sufficient blow-up margin in the PS. Machine Development (MD) sessions were carried out in LEIR to investigate methods to satisfy these stricter requirements. Two main ingredients were found to reduce longitudinal emittance. The first and most important was to adjust carefully the frequency offset at capture in order to align the RF with the position where the beam is deposited by the electron cooling system prior to acceleration. The second ingredient was to reduce the final bucket area in order to reduce any residual filamentation during capture. This note documents the results obtaine...

  1. Beam diagnostics

    International Nuclear Information System (INIS)

    Bogaty, J.; Clifft, B.E.; Zinkann, G.P.; Pardo, R.C.

    1995-01-01

    The ECR-PII injector beam line is operated at a fixed ion velocity. The platform high voltage is chosen so that all ions have a velocity of 0.0085c at the PII entrance. If a previous tune configuration for the linac is to be used, the beam arrival time must be matched to the previous tune as well. A nondestructive beam-phase pickup detector was developed and installed at the entrance to the PII linac. This device provides continuous phase and beam current information and allows quick optimization of the beam injected into PII. Bunches traverse a short tubular electrode thereby inducing displacement currents. These currents are brought outside the vacuum interface where a lumped inductance resonates electrode capacitance at one of the bunching harmonic frequencies. This configuration yields a basic sensitivity of a few hundred millivolts signal per microampere of beam current. Beam-induced radiofrequency signals are summed against an offset frequency generated by our master oscillator. The resulting kilohertz difference frequency conveys beam intensity and bunch phase information which is sent to separate processing channels. One channel utilizes a phase locked loop which stabilizes phase readings if beam is unstable. The other channel uses a linear full wave active rectifier circuit which converts kilohertz sine wave signal amplitude to a D.C. voltage representing beam current. A prototype set of electronics is now in use with the detector and we began to use the system in operation to set the arrival beam phase. A permanent version of the electronics system for the phase detector is now under construction. Additional nondestructive beam intensity and phase monitors at the open-quotes Boosterclose quotes and open-quotes ATLASclose quotes linac sections are planned as well as on some of the high-energy beam lines. Such a monitor will be particularly useful for FMA experiments where the primary beam hits one of the electric deflector plates

  2. End-of-Fill Diffusion and Halo Population Measurements with Physics Beams at 6.5 TeV

    CERN Document Server

    Valentino, Gianluca; Gorzawski, Arkadiusz; Redaelli, Stefano; Trad, Georges; Wagner, Joschka; Xu, Chen; CERN. Geneva. ATS Department

    2017-01-01

    Beam halo measurements at 6.5 TeV in the LHC were conducted with a full physics beam via collimator scrapings in end-of-fill MDs carried out in May and July 2016. From the time evolution of the beam losses in a collimator scan, it is possible to extract information on the halo diffusion and population. In the first MD, six scans were performed with two collimators in the vertical and horizontal planes in B1 and B2 respectively. The scans were done with squeezed colliding beams, with and without a gentle continuous transverse blow-up with the ADT (transverse damper) on a non-colliding bunch train. In the second MD, four scans were performed with the same collimators with squeezed colliding beams. The beam losses observed with the standard ionization chamber BLMs are compared to the diamond BLMs, and parametric fits of the diffusion model are applied to temporal loss patterns from colliding and non-colliding bunch trains. The results presented in this note also include the particle escape times and frequency an...

  3. Elliptical beams.

    Science.gov (United States)

    Bandres, Miguel A; Gutiérrez-Vega, Julio C

    2008-12-08

    A very general beam solution of the paraxial wave equation in elliptic cylindrical coordinates is presented. We call such a field an elliptic beam (EB). The complex amplitude of the EB is described by either the generalized Ince functions or the Whittaker-Hill functions and is characterized by four parameters that are complex in the most general situation. The propagation through complex ABCD optical systems and the conditions for square integrability are studied in detail. Special cases of the EB are the standard, elegant, and generalized Ince-Gauss beams, Mathieu-Gauss beams, among others.

  4. Superresolution beams

    CSIR Research Space (South Africa)

    Ngcobo, S

    2012-07-01

    Full Text Available positions of p zeros of intensity distributions on the Gaussian beam, resulting to a generation of TEMp0 beams where there are minimum losses. The LGBs are well-known family of exact orthogonal solutions of free-space paraxial wave equation in cylindrical...

  5. Beam diagnostics

    CERN Document Server

    Raich, U

    2008-01-01

    Most beam measurements are based on the electro-magnetic interaction of fields induced by the beam with their environment. Beam current transformers as well as beam position monitors are based on this principle. The signals induced in the sensors must be amplified and shaped before they are converted into numerical values. These values are further treated numerically in order to extract meaningful machine parameter measurements. The lecture introduces the architecture of an instrument and shows where in the treatment chain digital signal analysis can be introduced. Then the use of digital signal processing is presented using tune measurements, orbit and trajectory measurements as well as beam loss detection and longitudinal phase space tomography as examples. The hardware as well as the treatment algorithms and their implementation on Digital Signal Processors (DSPs) or in Field Programmable Gate Arrays (FPGAs) are presented.

  6. Molecular beams

    International Nuclear Information System (INIS)

    Ramsey, N.F.

    1985-01-01

    This book is a timeless and rather complete theoretical and experimental treatment of electric and magnetic resonance molecular-beam experiments for studying the radio frequency spectra of atoms and molecules. The theory of interactions of the nucleus with atomic and molecular fields is extensively presented. Measurements of atomic and nuclear magnetic moments, electric multipole moments, and atomic fine and hyperfine structure are detailed. Useful but somewhat outdated chapters on gas kinetics, molecular beam design, and experimental techniques are also included

  7. Beam transport

    International Nuclear Information System (INIS)

    1988-01-01

    Considerable experience has now been gained with the various beam transport lines, and a number of minor changes have been made to improve the ease of operation. These include: replacement of certain little-used slits by profile monitors (harps or scanners); relocation of steering magnets, closer to diagnostic harps or profile scanners; installation of a scanner inside the isocentric neutron therapy system; and conversion of a 2-doublet quadrupole telescope (on the neutron therapy beamline) to a 2-triplet telescope. The beam-swinger project has been delayed by very late delivery of the magnet iron to the manufacturer, but is now progressing smoothly. The K=600 spectrometer magnets have now been delivered and are being assembled for field mapping. The x,y-table with its associated mapping equipment is complete, together with the driver software. One of the experimental areas has been dedicated to the production of collimated neutron beams and has been equipped with a bending magnet and beam dump, together with steel collimators fixed at 4 degrees intervals from 0 degrees to 16 degrees. Changes to the target cooling and shielding system for isotope production have led to a request for much smaller beam spot sizes on target, and preparations have been made for rearrangement of the isotope beamline to permit installation of quadrupole triplets on the three beamlines after the switching magnet. A practical system of quadrupoles for matching beam properties to the spectrometer has been designed. 6 figs

  8. Quantum beams

    International Nuclear Information System (INIS)

    Uesaka, Mitsuru

    2003-01-01

    Present state and future prospect are described on quantum beams for medical use. Efforts for compactness of linac for advanced cancer therapy have brought about the production of machines like Accuray's CyberKnife and TOMOTHERAPY (Tomo Therapy Inc.) where the acceleration frequency of X-band (9-11 GHz) is used. For cervical vein angiography by the X-band linac, a compact hard X-ray source is developed which is based on the (reverse) Compton scattering through laser-electron collision. More intense beam and laser are necessary at present. A compact machine generating the particle beam of 10 MeV-1 GeV (laser-plasma accelerator) for cancer therapy is also developed using the recent compression technique (chirped-pulse amplification) to generate laser of >10 TW. Tokyo University is studying for the electron beam with energy of GeV order, for the laser-based synchrotron X-ray, and for imaging by the short pulse ion beam. Development of advanced compact accelerators is globally attempted. In Japan, a virtual laboratory by National Institute of Radiological Sciences (NIRS), a working group of universities and research facilities through the Ministry of Education, Culture, Sports, Science and Technology, started in 2001 for practical manufacturing of the above-mentioned machines for cancer therapy and for angiography. Virtual Factory (Inc.), a business venture, is to be stood in future. (N.I.)

  9. BEAM-BEAM SIMULATIONS FOR DOUBLE-GAUSSIAN BEAMS.

    Energy Technology Data Exchange (ETDEWEB)

    MONTAG, C.; MALITSKY, N.; BEN-ZVI, I.; LITVINENKO, V.

    2005-05-16

    Electron cooling together with intra-beam scattering results in a transverse distribution that can best be described by a sum of two gaussians, one for the high-density core and one for the tails of the distribution. Simulation studies are being performed to understand the beam-beam interaction of these double-gaussian beams. Here we report the effect of low-frequency random tune modulations on diffusion in double-gaussian beams and compare the effects to those in beam-beam interactions with regular gaussian beams and identical tune shift parameters.

  10. BEAM-BEAM SIMULATIONS FOR DOUBLE-GAUSSIAN BEAMS

    International Nuclear Information System (INIS)

    MONTAG, C.; MALITSKY, N.; BEN-ZVI, I.; LITVINENKO, V.

    2005-01-01

    Electron cooling together with intra-beam scattering results in a transverse distribution that can best be described by a sum of two gaussians, one for the high-density core and one for the tails of the distribution. Simulation studies are being performed to understand the beam-beam interaction of these double-gaussian beams. Here we report the effect of loW--frequency random tune modulations on diffusion in double-gaussian beams and compare the effects to those in beam-beam interactions with regular gaussian beams and identical tune shift parameters

  11. Beam-Beam Simulations for Double-Gaussian Beams

    CERN Document Server

    Montag, Christoph; Litvinenko, Vladimir N; Malitsky, Nikolay

    2005-01-01

    Electron cooling together with intra-beam scattering results in a transverse distribution that can best be described by a sum of two Gaussians, one for the high-density core and one for the tails of the distribution. Simulation studies are being performed to understand the beam-beam interaction of these double-Gaussian beams. Here we report the effect of low-frequency random tune modulations on diffusion in double-Gaussian beams and compare the effects to those in beam-beam interactions with regular Gaussian beams and identical tuneshift parameters.

  12. Beam transport

    International Nuclear Information System (INIS)

    1988-01-01

    The beam diagnostic components for both the transfer and the high-energy beamlines perform well except for some of the scanners whose noise pick-up has become a problem, especially at low beam intensities. This noise pick-up is primarily due to deterioration of the bearings in the scanner. At some locations in the high-energy beamlines, scanners were replaced by harps as the scanners proved to be practically useless for the low-intensity beams required in the experimental areas. The slits in the low-energy beamline, which are not water-cooled, have to be repaired at regular intervals because of vacuum leaks. Overheating causes the ceramic feedthroughs to deteriorate resulting in the vacuum leaks. Water-cooled slits have been ordered to replace the existing slits which will later be used in the beamlines associated with the second injector cyclotron SPC2. The current-measurement system will be slightly modified and should then be much more reliable. 3 figs

  13. Beam divergence scaling in neutral beam injectors

    International Nuclear Information System (INIS)

    Holmes, A.J.T.

    1976-01-01

    One of the main considerations in the design of neutral beam injectors is to monimize the divergence of the primary ion beam and hence maximize the beam transport and minimize the input of thermal gas. Experimental measurements of the divergence of a cylindrical ion beam are presented and these measurements are used to analyze the major components of ion beam divergence, namely: space charge expansion, gas-ion scattering, emittance and optical aberrations. The implication of these divergence components in the design of a neutral beam injector system is discussed and a method of maximizing the beam current is described for a given area of source plasma

  14. Beam screens for the LHC beam pipes

    CERN Multimedia

    Patrice Loïez

    1997-01-01

    Cross-section of LHC prototype beam pipes showing the beam screens. Slits in the screens allow residual gas molecules to be pumped out and become frozen to the walls of the ultra-cold beam pipe. Beam screens like these have been designed to line the beam pipes, absorbing radiation before it can hit the magnets and warm them up, an effect that would greatly reduce the magnetic field and cause serious damage.

  15. Beam geometry selection using sequential beam addition.

    Science.gov (United States)

    Popple, Richard A; Brezovich, Ivan A; Fiveash, John B

    2014-05-01

    The selection of optimal beam geometry has been of interest since the inception of conformal radiotherapy. The authors report on sequential beam addition, a simple beam geometry selection method, for intensity modulated radiation therapy. The sequential beam addition algorithm (SBA) requires definition of an objective function (score) and a set of candidate beam geometries (pool). In the first iteration, the optimal score is determined for each beam in the pool and the beam with the best score selected. In the next iteration, the optimal score is calculated for each beam remaining in the pool combined with the beam selected in the first iteration, and the best scoring beam is selected. The process is repeated until the desired number of beams is reached. The authors selected three treatment sites, breast, lung, and brain, and determined beam arrangements for up to 11 beams from a pool comprised of 25 equiangular transverse beams. For the brain, arrangements were additionally selected from a pool of 22 noncoplanar beams. Scores were determined for geometries comprised equiangular transverse beams (EQA), as well as two tangential beams for the breast case. In all cases, SBA resulted in scores superior to EQA. The breast case had the strongest dependence on beam geometry, for which only the 7-beam EQA geometry had a score better than the two tangential beams, whereas all SBA geometries with more than two beams were superior. In the lung case, EQA and SBA scores monotonically improved with increasing number of beams; however, SBA required fewer beams to achieve scores equivalent to EQA. For the brain case, SBA with a coplanar pool was equivalent to EQA, while the noncoplanar pool resulted in slightly better scores; however, the dose-volume histograms demonstrated that the differences were not clinically significant. For situations in which beam geometry has a significant effect on the objective function, SBA can identify arrangements equivalent to equiangular

  16. Beam geometry selection using sequential beam addition

    Energy Technology Data Exchange (ETDEWEB)

    Popple, Richard A., E-mail: rpopple@uabmc.edu; Brezovich, Ivan A.; Fiveash, John B. [Department of Radiation Oncology, The University of Alabama at Birmingham, 1720 2nd Avenue South, Birmingham, Alabama 35294 (United States)

    2014-05-15

    Purpose: The selection of optimal beam geometry has been of interest since the inception of conformal radiotherapy. The authors report on sequential beam addition, a simple beam geometry selection method, for intensity modulated radiation therapy. Methods: The sequential beam addition algorithm (SBA) requires definition of an objective function (score) and a set of candidate beam geometries (pool). In the first iteration, the optimal score is determined for each beam in the pool and the beam with the best score selected. In the next iteration, the optimal score is calculated for each beam remaining in the pool combined with the beam selected in the first iteration, and the best scoring beam is selected. The process is repeated until the desired number of beams is reached. The authors selected three treatment sites, breast, lung, and brain, and determined beam arrangements for up to 11 beams from a pool comprised of 25 equiangular transverse beams. For the brain, arrangements were additionally selected from a pool of 22 noncoplanar beams. Scores were determined for geometries comprised equiangular transverse beams (EQA), as well as two tangential beams for the breast case. Results: In all cases, SBA resulted in scores superior to EQA. The breast case had the strongest dependence on beam geometry, for which only the 7-beam EQA geometry had a score better than the two tangential beams, whereas all SBA geometries with more than two beams were superior. In the lung case, EQA and SBA scores monotonically improved with increasing number of beams; however, SBA required fewer beams to achieve scores equivalent to EQA. For the brain case, SBA with a coplanar pool was equivalent to EQA, while the noncoplanar pool resulted in slightly better scores; however, the dose-volume histograms demonstrated that the differences were not clinically significant. Conclusions: For situations in which beam geometry has a significant effect on the objective function, SBA can identify

  17. Stable beams

    CERN Multimedia

    2015-01-01

    Stable beams: two simple words that carry so much meaning at CERN. When LHC page one switched from "squeeze" to "stable beams" at 10.40 a.m. on Wednesday, 3 June, it triggered scenes of jubilation in control rooms around the CERN sites, as the LHC experiments started to record physics data for the first time in 27 months. This is what CERN is here for, and it’s great to be back in business after such a long period of preparation for the next stage in the LHC adventure.   I’ve said it before, but I’ll say it again. This was a great achievement, and testimony to the hard and dedicated work of so many people in the global CERN community. I could start to list the teams that have contributed, but that would be a mistake. Instead, I’d simply like to say that an achievement as impressive as running the LHC – a machine of superlatives in every respect – takes the combined effort and enthusiasm of everyone ...

  18. The direct injection of intense ion beams from a high field electron cyclotron resonance ion source into a radio frequency quadrupole

    Science.gov (United States)

    Rodrigues, G.; Becker, R.; Hamm, R. W.; Baskaran, R.; Kanjilal, D.; Roy, A.

    2014-02-01

    The ion current achievable from high intensity ECR sources for highly charged ions is limited by the high space charge. This makes classical extraction systems for the transport and subsequent matching to a radio frequency quadrupole (RFQ) accelerator less efficient. The direct plasma injection (DPI) method developed originally for the laser ion source avoids these problems and uses the combined focusing of the gap between the ion source and the RFQ vanes (or rods) and the focusing of the rf fields from the RFQ penetrating into this gap. For high performance ECR sources that use superconducting solenoids, the stray magnetic field of the source in addition to the DPI scheme provides focusing against the space charge blow-up of the beam. A combined extraction/matching system has been designed for a high performance ECR ion source injecting into an RFQ, allowing a total beam current of 10 mA from the ion source for the production of highly charged 238U40+ (1.33 mA) to be injected at an ion source voltage of 60 kV. In this design, the features of IGUN have been used to take into account the rf-focusing of an RFQ channel (without modulation), the electrostatic field between ion source extraction and the RFQ vanes, the magnetic stray field of the ECR superconducting solenoid, and the defocusing space charge of an ion beam. The stray magnetic field is shown to be critical in the case of a matched beam.

  19. The direct injection of intense ion beams from a high field electron cyclotron resonance ion source into a radio frequency quadrupole.

    Science.gov (United States)

    Rodrigues, G; Becker, R; Hamm, R W; Baskaran, R; Kanjilal, D; Roy, A

    2014-02-01

    The ion current achievable from high intensity ECR sources for highly charged ions is limited by the high space charge. This makes classical extraction systems for the transport and subsequent matching to a radio frequency quadrupole (RFQ) accelerator less efficient. The direct plasma injection (DPI) method developed originally for the laser ion source avoids these problems and uses the combined focusing of the gap between the ion source and the RFQ vanes (or rods) and the focusing of the rf fields from the RFQ penetrating into this gap. For high performance ECR sources that use superconducting solenoids, the stray magnetic field of the source in addition to the DPI scheme provides focusing against the space charge blow-up of the beam. A combined extraction/matching system has been designed for a high performance ECR ion source injecting into an RFQ, allowing a total beam current of 10 mA from the ion source for the production of highly charged (238)U(40+) (1.33 mA) to be injected at an ion source voltage of 60 kV. In this design, the features of IGUN have been used to take into account the rf-focusing of an RFQ channel (without modulation), the electrostatic field between ion source extraction and the RFQ vanes, the magnetic stray field of the ECR superconducting solenoid, and the defocusing space charge of an ion beam. The stray magnetic field is shown to be critical in the case of a matched beam.

  20. Beam-beam effects in the Tevatron

    Energy Technology Data Exchange (ETDEWEB)

    Shiltsev, V.; Alexahin, Y.; Lebedev, V.; Lebrun, P.; Moore, R.S.; Sen, T.; Tollestrup, A.; Valishev, A.; Zhang, X.L.; /Fermilab

    2005-01-01

    The Tevatron in Collider Run II (2001-present) is operating with 6 times more bunches, many times higher beam intensities and luminosities than in Run I (1992-1995). Electromagnetic long-range and head-on interactions of high intensity proton and antiproton beams have been significant sources of beam loss and lifetime limitations. We present observations of the beam-beam phenomena in the Tevatron and results of relevant beam studies. We analyze the data and various methods employed in operations, predict the performance for planned luminosity upgrades, and discuss ways to improve it.

  1. Crystalline beams

    International Nuclear Information System (INIS)

    Schiffer, J.P.

    1989-01-01

    Ions in a storage ring are confined to a mean orbit by focusing elements. To a first approximation these may be described by a constant harmonic restoring force: F = -Kr. If the particles in the frame moving along with the beam have small random thermal energies, then they will occupy a cylindrical volume around the mean orbit and the focusing force will be balanced by that from the mutual repulsion of the particles. Inside the cylinder only residual two-particle interactions will play a significant role and some form of ordering might be expected to take place. The results of some of the first MD calculations showed a surprising result: not only were the particles arranged in the form of a tube, but they formed well-defined layers: concentric shells, with the particles in each shell arranged in a hexagonal lattice that is characteristic of two-dimensional Coulomb systems. This paper discusses the condense layer structure

  2. Beam halo in high-intensity beams

    International Nuclear Information System (INIS)

    Wangler, T.P.

    1993-01-01

    In space-charge dominated beams the nonlinear space-charge forces produce a filamentation pattern, which in projection to the 2-D phase spaces results in a 2-component beam consisting of an inner core and a diffuse outer halo. The beam-halo is of concern for a next generation of cw, high-power proton linacs that could be applied to intense neutron generators for nuclear materials processing. The author describes what has been learned about beam halo and the evolution of space-charge dominated beams using numerical simulations of initial laminar beams in uniform linear focusing channels. Initial results are presented from a study of beam entropy for an intense space-charge dominated beam

  3. Stability of longitudinal modes in a bunched beam with mode coupling

    International Nuclear Information System (INIS)

    Satoh, K.

    1981-06-01

    In this paper we study a longitudinal coherent bunch instability in which the growth time is comparable to or less than the period of synchrotron oscillations. Both longitudinal and transverse bunch instabilities have been studied. In most treatments, however, the coherent force is assumed to be small and is treated as a perturbation compared with the synchrotron force. This makes the problem simpler because an individual synchrotron mode is decoupled. As bunch current increases, the coherent force is no longer small and the mode frequency shift becomes significant compared with the synchrotron frequency. Therefore in this case it is necessary to include coupling of the synchrotron modes. Recently a fast blow-up instability which comes from mode coupling was studied. Their method is to derive a dispersion relation for a bunched beam using the Vlasov equation and to analyze it as in a coasting beam. They showed that if mode coupling is included the Vlasov equation predicts a fast microwave instability with a stability condition similar to that for a coasting beam. In this paper we will partly follow their method and present a formalism which includes coupling between higher-order radial modes as well as coupling between synchrotron modes. The formalism is considered to be generalization of the Sacherer formalism without mode coupling. This theory predicts that instability is induced not only by coupling between different synchrotron modes, but also by coupling between positive and negative modes, since negative synchrotron modes are included in the theory in a natural manner. This formalism is to be used for a Gaussian bunch and a parabolic bunch, and is also useful for transverse problems

  4. Electron beam control for barely separated beams

    Energy Technology Data Exchange (ETDEWEB)

    Douglas, David R.; Ament, Lucas J. P.

    2017-04-18

    A method for achieving independent control of multiple beams in close proximity to one another, such as in a multi-pass accelerator where coaxial beams are at different energies, but moving on a common axis, and need to be split into spatially separated beams for efficient recirculation transport. The method for independent control includes placing a magnet arrangement in the path of the barely separated beams with the magnet arrangement including at least two multipole magnets spaced closely together and having a multipole distribution including at least one odd multipole and one even multipole. The magnetic fields are then tuned to cancel out for a first of the barely separated beams to allow independent control of the second beam with common magnets. The magnetic fields may be tuned to cancel out either the dipole component or tuned to cancel out the quadrupole component in order to independently control the separate beams.

  5. Literature in Focus Beta Beams: Neutrino Beams

    CERN Multimedia

    2009-01-01

    By Mats Lindroos (CERN) and Mauro Mezzetto (INFN Padova, Italy) Imperial Press, 2009 The beta-beam concept for the generation of electron neutrino beams was first proposed by Piero Zucchelli in 2002. The idea created quite a stir, challenging the idea that intense neutrino beams only could be produced from the decay of pions or muons in classical neutrino beams facilities or in future neutrino factories. The concept initially struggled to make an impact but the hard work by many machine physicists, phenomenologists and theoreticians over the last five years has won the beta-beam a well-earned position as one of the frontrunners for a possible future world laboratory for high intensity neutrino oscillation physics. This is the first complete monograph on the beta-beam concept. The book describes both technical aspects and experimental aspects of the beta-beam, providing students and scientists with an insight into the possibilities o...

  6. Beam Techniques - Beam Control and Manipulation

    Energy Technology Data Exchange (ETDEWEB)

    Minty, Michiko G

    2003-04-24

    We describe commonly used strategies for the control of charged particle beams and the manipulation of their properties. Emphasis is placed on relativistic beams in linear accelerators and storage rings. After a brief review of linear optics, we discuss basic and advanced beam control techniques, such as transverse and longitudinal lattice diagnostics, matching, orbit correction and steering, beam-based alignment, and linac emittance preservation. A variety of methods for the manipulation of particle beam properties are also presented, for instance, bunch length and energy compression, bunch rotation, changes to the damping partition number, and beam collimation. The different procedures are illustrated by examples from various accelerators. Special topics include injection and extraction methods, beam cooling, spin transport and polarization.

  7. ISR beam scrapers

    CERN Multimedia

    CERN PhotoLab

    1972-01-01

    Beam scrapers seen in the direction of the beam. The two horizontal scraper foils are near the centre of the beam pipe andthe two scrapers for protection of the vacuum chamber are further outside. In the lower part of the beam pipe is the vertical halo scraping blade.

  8. Telecommunication using muon beams

    International Nuclear Information System (INIS)

    Arnold, R.C.

    1976-01-01

    Telecommunication is effected by generating a beam of mu mesons or muons, varying a property of the beam at a modulating rate to generate a modulated beam of muons, and detecting the information in the modulated beam at a remote location

  9. Analysis of orthotropic beams

    Science.gov (United States)

    Jen Y. Liu; S. Cheng

    1979-01-01

    A plane-stress analysis of orthotropic or isotropic beams is presented. The loading conditions considered are: (1) a concentrated normal load arbitrarily located on the beam, and (2) a distributed normal load covering an arbitrary length of the beam. exhibit close agreement with existing experimental data from Sitka spruce beams. Other loading conditions can similarly...

  10. Telecommunication using muon beams

    Science.gov (United States)

    Arnold, Richard C.

    1976-01-01

    Telecommunication is effected by generating a beam of mu mesons or muons, varying a property of the beam at a modulating rate to generate a modulated beam of muons, and detecting the information in the modulated beam at a remote location.

  11. LANSCE beam current limiter

    International Nuclear Information System (INIS)

    Gallegos, F.R.

    1996-01-01

    The Radiation Security System (RSS) at the Los Alamos Neutron Science Center (LANSCE) provides personnel protection from prompt radiation due to accelerated beam. Active instrumentation, such as the Beam Current Limiter, is a component of the RSS. The current limiter is designed to limit the average current in a beam line below a specific level, thus minimizing the maximum current available for a beam spill accident. The beam current limiter is a self-contained, electrically isolated toroidal beam transformer which continuously monitors beam current. It is designed as fail-safe instrumentation. The design philosophy, hardware design, operation, and limitations of the device are described

  12. The beam dump tunnels

    CERN Multimedia

    Patrice Loïez

    2002-01-01

    In these images workers are digging the tunnels that will be used to dump the counter-circulating beams. Travelling just a fraction under the speed of light, the beams at the LHC will each carry the energy of an aircraft carrier travelling at 12 knots. In order to dispose of these beams safely, a beam dump is used to extract the beam and diffuse it before it collides with a radiation shielded graphite target.

  13. Ion beam diagnosis

    International Nuclear Information System (INIS)

    Strehl, P.

    1994-04-01

    This report is an introduction to ion beam diagnosis. After a short description of the most important ion beam parameters measurements of the beam current by means of Faraday cups, calorimetry, and beam current transformers and measurements of the beam profile by means of viewing screens, profile grids and scanning devices, and residual gas ionization monitors are described. Finally measurements in the transverse and longitudinal phase space are considered. (HSI)

  14. Beam diagnostics for low energy beams

    Directory of Open Access Journals (Sweden)

    J. Harasimowicz

    2012-12-01

    Full Text Available Low-energetic ion and antimatter beams are very attractive for a number of fundamental studies. The diagnostics of such beams, however, is a challenge due to low currents down to only a few thousands of particles per second and significant fraction of energy loss in matter at keV beam energies. A modular set of particle detectors has been developed to suit the particular beam diagnostic needs of the ultralow-energy storage ring (USR at the future facility for low-energy antiproton and ion research, accommodating very low beam intensities at energies down to 20 keV. The detectors include beam-profile monitors based on scintillating screens and secondary electron emission, sensitive Faraday cups for absolute intensity measurements, and capacitive pickups for beam position monitoring. In this paper, the design of all detectors is presented in detail and results from beam measurements are shown. The resolution limits of all detectors are described and options for further improvement summarized. Whilst initially developed for the USR, the instrumentation described in this paper is also well suited for use in other low-intensity, low-energy accelerators, storage rings, and beam lines.

  15. Revisit of combined parallel-beam/cone-beam or fan-beam/cone-beam imaging.

    Science.gov (United States)

    Zeng, Gengsheng L

    2013-10-01

    This aim of this paper is to revisit the parallel-beam/cone-beam or fan-beam/cone-beam imaging configuration, and to investigate whether this configuration has any advantages. Twenty years ago, it was suggested to simultaneously use a parallel-beam (or a fan-beam) collimator and a cone-beam collimator to acquire single photon emission computed tomography data. The motivation was that the parallel-beam (or the fan-beam) collimator can provide sufficient sampling, while the cone-beam collimator is able to provide higher photon counts. Even with higher total counts, this hybrid system does not give significant improvement (if any) in terms of image noise and artifacts reduction. If a conventional iterative maximum-likelihood expectation-maximization algorithm is used to reconstruct the image, the resultant reconstruction may be worse than the parallel-beam-only (or fan-beam-only) system. This paper uses the singular value decomposition (SVD) analysis to explain this phenomenon. The SVD results indicate that the parallel-beam-only and the fan-beam-only system outperform the combined systems. The optimal imaging system does not necessary to be the one that generates the projections with highest signal-to-noise ratio and best resolution.

  16. Low current beam techniques

    Energy Technology Data Exchange (ETDEWEB)

    Saint, A.; Laird, J.S.; Bardos, R.A.; Legge, G.J.F. [Melbourne Univ., Parkville, VIC (Australia). School of Physics; Nishijima, T.; Sekiguchi, H. [Electrotechnical Laboratory, Tsukuba (Japan).

    1993-12-31

    Since the development of Scanning Transmission Microscopy (STIM) imaging in 1983 many low current beam techniques have been developed for the scanning (ion) microprobe. These include STIM tomography, Ion Beam Induced Current, Ion Beam Micromachining and Microlithography and Ionoluminense. Most of these techniques utilise beam currents of 10{sup -15} A down to single ions controlled by beam switching techniques This paper will discuss some of the low beam current techniques mentioned above, and indicate, some of their recent applications at MARC. A new STIM technique will be introduced that can be used to obtain Z-contrast with STIM resolution. 4 refs., 3 figs.

  17. Beam Dynamics and Beam Losses - Circular Machines

    CERN Document Server

    Kain, V

    2016-01-01

    A basic introduction to transverse and longitudinal beam dynamics as well as the most relevant beam loss mechanisms in circular machines will be presented in this lecture. This lecture is intended for physicists and engineers with little or no knowledge of this subject.

  18. T10 Beam Studies & Beam Simulation

    CERN Document Server

    Bergmann, Michael Georges; Van Dijk, Maarten; CERN. Geneva. EN Department

    2017-01-01

    In order to test detector components before their installation in actual experiments, one uses test beams in which one can control particle typ, momentum and size to high degree. For this project the focus of a secondary beam at T10 in the East Area at CERN was analysed using an AZALEA telescope from DESY.

  19. BEAMS3D Neutral Beam Injection Model

    Energy Technology Data Exchange (ETDEWEB)

    Lazerson, Samuel

    2014-04-14

    With the advent of applied 3D fi elds in Tokamaks and modern high performance stellarators, a need has arisen to address non-axisymmetric effects on neutral beam heating and fueling. We report on the development of a fully 3D neutral beam injection (NBI) model, BEAMS3D, which addresses this need by coupling 3D equilibria to a guiding center code capable of modeling neutral and charged particle trajectories across the separatrix and into the plasma core. Ionization, neutralization, charge-exchange, viscous velocity reduction, and pitch angle scattering are modeled with the ADAS atomic physics database [1]. Benchmark calculations are presented to validate the collisionless particle orbits, neutral beam injection model, frictional drag, and pitch angle scattering effects. A calculation of neutral beam heating in the NCSX device is performed, highlighting the capability of the code to handle 3D magnetic fields.

  20. Successful Beam-Beam Tuneshift Compensation

    Energy Technology Data Exchange (ETDEWEB)

    Bishofberger, Kip Aaron [Univ. of California, Los Angeles, CA (United States)

    2005-01-01

    The performance of synchrotron colliders has been limited by the beam-beam limit, a maximum tuneshift that colliding bunches could sustain. Due to bunch-to-bunch tune variation and intra-bunch tune spread, larger tuneshifts produce severe emittance growth. Breaking through this constraint has been viewed as impossible for several decades. This dissertation introduces the physics of ultra-relativistic synchrotrons and low-energy electron beams, with emphasis placed on the limits of the Tevatron and the needs of a tuneshift-compensation device. A detailed analysis of the Tevatron Electron Lens (TEL) is given, comparing theoretical models to experimental data whenever possible. Finally, results of Tevatron operations with inclusion of the TEL are presented and analyzed. It is shown that the TEL provides a way to shatter the previously inescapable beam-beam limit.

  1. Beam Loss in Linacs

    CERN Document Server

    Plum, M.A.

    2016-01-01

    Beam loss is a critical issue in high-intensity accelerators, and much effort is expended during both the design and operation phases to minimize the loss and to keep it to manageable levels. As new accelerators become ever more powerful, beam loss becomes even more critical. Linacs for H- ion beams, such as the one at the Oak Ridge Spallation Neutron Source, have many more loss mechanisms compared to H+ (proton) linacs, such as the one being designed for the European Spallation Neutron Source. Interesting H- beam loss mechanisms include residual gas stripping, H+ capture and acceleration, field stripping, black-body radiation and the recently discovered intra-beam stripping mechanism. Beam halo formation, and ion source or RF turn on/off transients, are examples of beam loss mechanisms that are common for both H+ and H- accelerators. Machine protection systems play an important role in limiting the beam loss.

  2. Beam scanning system

    International Nuclear Information System (INIS)

    Enge, H.A.

    1977-01-01

    A system for deflecting a beam of particles having different momenta, preferably through a 90 0 angle, so as to cause the beam to impinge upon a moving target and to scan across the target is described. The system includes a means responsive to a beam from a suitable source for causing the beam to periodically scan in a scanning plane and further means for deflecting the periodically scanned beam through the desired angle in a deflection plane so that the deflected beam impinges on the target. Means are included in the system for reducing the momentum dispersion at the target in both the deflection and the scanning planes and for spatially focussing the beam so as to produce a desired beam diameter at the target

  3. Crossed beam experiments

    International Nuclear Information System (INIS)

    Dolder, K.T.

    1976-01-01

    Many natural phenomena can only be properly understood if one has a detailed knowledge of interactions involving atoms, molecules, ions, electrons or photons. In the laboratory these processes are often studied by preparing beams of two types of particle and observing the reactions which occur when the beams intersect. Some of the more interesting of these crossed beam experiments and their results are discussed. Proposals to extend colliding beam techniques to high energy particle physics are also outlined. (author)

  4. An Electromagnetic Beam Converter

    DEFF Research Database (Denmark)

    2009-01-01

    The present invention relates to an electromagnetic beam converter and a method for conversion of an input beam of electromagnetic radiation having a bell shaped intensity profile a(x,y) into an output beam having a prescribed target intensity profile l(x',y') based on a further development...

  5. Beams 92: Proceedings

    International Nuclear Information System (INIS)

    Mosher, D.; Cooperstein, G.

    1993-01-01

    This report contains papers on the following topics: Ion beam papers; electron beam, bremsstrahlung, and diagnostics papers; radiating Z- pinch papers; microwave papers; electron laser papers; advanced accelerator papers; beam and pulsed power applications papers; pulsed power papers; and these papers have been indexed separately elsewhere

  6. Blow-Ups in Generalized Complex Geometry

    NARCIS (Netherlands)

    van der Leer Duran, J.L.

    2016-01-01

    Generalized complex geometry is a theory that unifies complex geometry and symplectic geometry into one single framework. It was introduced by Hitchin and Gualtieri around 2002. In this thesis we address the following question: given a generalized complex manifold together with a submanifold, does

  7. Laser beam shaping techniques

    Energy Technology Data Exchange (ETDEWEB)

    DICKEY,FRED M.; WEICHMAN,LOUIS S.; SHAGAM,RICHARD N.

    2000-03-16

    Industrial, military, medical, and research and development applications of lasers frequently require a beam with a specified irradiance distribution in some plane. A common requirement is a laser profile that is uniform over some cross-section. Such applications include laser/material processing, laser material interaction studies, fiber injection systems, optical data image processing, lithography, medical applications, and military applications. Laser beam shaping techniques can be divided into three areas: apertured beams, field mappers, and multi-aperture beam integrators. An uncertainty relation exists for laser beam shaping that puts constraints on system design. In this paper the authors review the basics of laser beam shaping and present applications and limitations of various techniques.

  8. Beam induced RF heating

    CERN Document Server

    Salvant, B; Arduini, G; Assmann, R; Baglin, V; Barnes, M J; Bartmann, W; Baudrenghien, P; Berrig, O; Bracco, C; Bravin, E; Bregliozzi, G; Bruce, R; Bertarelli, A; Carra, F; Cattenoz, G; Caspers, F; Claudet, S; Day, H; Garlasche, M; Gentini, L; Goddard, B; Grudiev, A; Henrist, B; Jones, R; Kononenko, O; Lanza, G; Lari, L; Mastoridis, T; Mertens, V; Métral, E; Mounet, N; Muller, J E; Nosych, A A; Nougaret, J L; Persichelli, S; Piguiet, A M; Redaelli, S; Roncarolo, F; Rumolo, G; Salvachua, B; Sapinski, M; Schmidt, R; Shaposhnikova, E; Tavian, L; Timmins, M; Uythoven, J; Vidal, A; Wenninger, J; Wollmann, D; Zerlauth, M

    2012-01-01

    After the 2011 run, actions were put in place during the 2011/2012 winter stop to limit beam induced radio frequency (RF) heating of LHC components. However, some components could not be changed during this short stop and continued to represent a limitation throughout 2012. In addition, the stored beam intensity increased in 2012 and the temperature of certain components became critical. In this contribution, the beam induced heating limitations for 2012 and the expected beam induced heating limitations for the restart after the Long Shutdown 1 (LS1) will be compiled. The expected consequences of running with 25 ns or 50 ns bunch spacing will be detailed, as well as the consequences of running with shorter bunch length. Finally, actions on hardware or beam parameters to monitor and mitigate the impact of beam induced heating to LHC operation after LS1 will be discussed.

  9. Craft Stick Beams

    Science.gov (United States)

    Karplus, Alan K.

    1996-01-01

    The objective of this exercise is to provide a phenomenological 'hands-on' experience that shows how geometry can affect the load carrying capacity of a material used in construction, how different materials have different failure characteristics, and how construction affects the performance of a composite material. This will be accomplished by building beams of a single material and composite beams of a mixture of materials (popsicle sticks, fiberboard sheets, and tongue depressors); testing these layered beams to determine how and where they fail; and based on the failure analysis, designing a layered beam that will fail in a predicted manner. The students will learn the effects of lamination, adhesion, and geometry in layered beam construction on beam strength and failure location.

  10. Beam Extraction and Transport

    CERN Document Server

    Kalvas, T.

    2013-12-16

    This chapter gives an introduction to low-energy beam transport systems, and discusses the typically used magnetostatic elements (solenoid, dipoles and quadrupoles) and electrostatic elements (einzel lens, dipoles and quadrupoles). The ion beam emittance, beam space-charge effects and the physics of ion source extraction are introduced. Typical computer codes for analysing and designing ion optical systems are mentioned, and the trajectory tracking method most often used for extraction simulations is described in more detail.

  11. Mechanical beam isolator

    International Nuclear Information System (INIS)

    Post, R.F.; Vann, C.S.

    1996-10-01

    Back-reflections from a target, lenses, etc. can gain energy passing backwards through a laser just like the main beam gains energy passing forwards. Unless something blocks these back-reflections early in their path, they can seriously damage the laser. A Mechanical Beam Isolator is a device that blocks back-reflections early, relatively inexpensively, and without introducing aberrations to the laser beam

  12. Cyclotron radiation beam control

    International Nuclear Information System (INIS)

    Dominke, P.

    1983-01-01

    This patent application describes an apparatus for attenuating a beam of particulate radiation comprising a series of modules, each module being constituted by a sphere having a passage, a cupola covering said sphere and a base supporting said sphere, and means for causing movement of the spheres for aligning said passages with an axis of a beam line and arranging said passages out of alignment so as to attenuate the beam. (author)

  13. Chilled beam application guidebook

    CERN Document Server

    Butler, David; Gräslund, Jonas; Hogeling, Jaap; Lund Kristiansen, Erik; Reinikanen, Mika; Svensson, Gunnar

    2007-01-01

    Chilled beam systems are primarily used for cooling and ventilation in spaces, which appreciate good indoor environmental quality and individual space control. Active chilled beams are connected to the ventilation ductwork, high temperature cold water, and when desired, low temperature hot water system. Primary air supply induces room air to be recirculated through the heat exchanger of the chilled beam. In order to cool or heat the room either cold or warm water is cycled through the heat exchanger.

  14. Who needs hyperon beams

    International Nuclear Information System (INIS)

    Lipkin, H.J.

    1976-01-01

    Hyperon beams can provide new interesting information about hadron structure and their strong, electromagnetic and weak interactions. The dependence of hadron interactions on strangeness and baryon number is not understood, and data from hyperon beams can provide new clues to paradoxes which arise in the interpretation of data from conventional beams. Examples of interesting data are total and differential cross sections, magnetic moments and values of Gsub(A)/Gsub(V) for weak semileptonic decays. (author)

  15. Instability of compensated beam-beam collisions

    International Nuclear Information System (INIS)

    Rosenzweig, J.B.; Autin, B.; Chen, Pisin.

    1989-01-01

    The beam-beam disruption phenomena in linear colliders are increasingly seen as a source of serious problems for these machines. A plasma compensation scheme, in which the motion of the plasma electrons in the presence of the colliding beams provides neutralizing charge and current densities, has been proposed and studied. But natural alternative to this scheme is to consider the overlapping of nearly identical high energy e + and e/sup /minus// bunches, and the collision of two such pairs - in other words, collision of two opposing relativistic positronium plasmas. It should be noticed that while the luminosity for all collisions is increased by a factor of four in this scheme, the event rate for e + e/sup /minus// collisions is only increased by a factor of two. The other factor of two corresponds to the addition of e + e + and e/sup /minus//e/sup /minus// collisions to the interaction point. This beam compensation scheme, which has been examined through computer simulation by Balakin and Solyak in the Soviet Union, promises full neutralization of beam charges and currents. These numerical investigations have shown that plasma instabilities exist in this nominally neutral system. Although the implementation of this idea seems technically daunting, the potential benefits (beamstrahlung and disruption suppression, relaxation of final focus system constraints) are such that we should consider the physics of these collisions further. In the remainder of this paper, we theoretically analyze the issues of stability and bunch parameter tolerances in this scheme. 11 refs

  16. Dual-beam CRT

    International Nuclear Information System (INIS)

    1975-01-01

    A dual-beam cathode-ray tube having a pair of electron guns and associated deflection means disposed side-by-side on each side of a central axis is described. The electron guns are parallel and the deflection means includes beam centering plates and angled horizontal deflection plates to direct the electron beams toward the central axis, precluding the need for a large-diameter tube neck in which the entire gun structures are angled. Bowing control plates are disposed adjacent to the beam centering plates to minimize trace bowing, and an intergun shield is disposed between the horizontal deflection plates to control and correct display pattern geometry distortion

  17. GANIL beam profile detectors

    International Nuclear Information System (INIS)

    Tribouillard, C.

    1997-01-01

    In the design phase of GANIL which started in 1977, one of the priorities of the project management was equipping the beamlines with a fast and efficient system for visualizing the beam position, thus making possible adjustment of the beam transport lines optics and facilitating beam control. The implantation of some thirty detectors was foreseen in the initial design. The assembly of installed detectors (around 190) proves the advantages of these detectors for displaying all the beams extracted from GANIL: transfer and transport lines, beam extracted from SISSI, very high intensity beam, secondary ion beams from the production target of the LISE and SPEG spectrometers, different SPIRAL project lines. All of these detectors are based on standard characteristics: - standard flange diameter (DN 160) with a standard booster for all the sensors; - identical analog electronics for all the detectors, with networking; - unique display system. The new micro-channel plate non-interceptive detectors (beam profile and ion packet lengths) make possible in-line control of the beam quality and accelerator stability. (author)

  18. ALFA beam halo

    CERN Document Server

    Komarek, Tomas

    2014-01-01

    This note serves as a final report about CERN Summer Student Programme 2014 project. The beam halo is an undesired phenomenon for physics analyses on particle accelerators. It surrounds the beam core and constitutes an important part of background for signal measurements on some detectors, eg. in the forward region. In this study, the data from the ALFA detector were used, specifically from the run 191373 ($\\beta^*=90\\unit{m}$) and the run 213268 ($\\beta^*=1\\unit{km}$). Using the ROOT framework, a software for beam halo events selection was created and beam halo properties were examined. In the run 213268, excessive beam halo is suspected to be the reason for multiple beam scrapings that occurred. A kinematic reconstruction of beam halo particles is attempted in order to understand beam halo properties in the interaction point. Some further simulations are employed to find constraints for beam halo particles in order to survive in the accelerator for a longer time/many revolutions. This work represents a st...

  19. Simulation of Beam-Beam Background at CLIC

    CERN Document Server

    Sailer, Andre

    2010-01-01

    The dense beams used at CLIC to achieve a high luminosity will cause a large amount of background particles through beam-beam interactions. Generator level studies with GuineaPig and full detector simulation studies with an ILD based CLIC detector have been performed to evaluate the amount of beam-beam background hitting the vertex detector.

  20. Simulation of Beam-Beam Background at CLIC

    CERN Document Server

    Sailer, A

    2010-01-01

    The dense beams used at CLIC to achieve a high luminosity will cause a large amount of background particles through beam-beam interactions. Generator level studies with GUINEAPIG and full detector simulation studies with an ILD based CLIC detector have been performed to evaluate the amount of beam-beam back- ground hitting the vertex detector.

  1. Identification of LHC beam loss mechanism: a deterministic treatment of loss patterns

    International Nuclear Information System (INIS)

    Marsili, A.

    2012-01-01

    the error on the re-composition and its correctness. The principles of vector decomposition are developed in chapter 3. An ensemble of well controlled loss scenarios (such as vertical and horizontal blow-up of the beams or momentum offset during collimator loss maps) has been gathered, in order to allow the study and creation of reference vectors. To achieve the Vector Decomposition, linear algebra (matrix inversion) is used with the numeric algorithm for the Singular Value Decomposition. Additionally, a specific code for vector projection on a non-orthogonal basis of a hyper-plane was developed. The implementation of the vector decomposition on the LHC data is described in chapter 4. After this, the use of the decomposition tools systematically on the time evolution of the losses will be described: first as a study of the variations second by second, then by comparison to a calculated default loss profile. The different ways to evaluate the variation are studied, and are presented in chapter 5. The chapter 6 describes the gathering of the decomposition results applied to the beam losses of 2011. The vector decomposition is applied on every second of the 'stable beams' periods, as a study of the spatial distribution of the loss. Several comparisons of the results given by the decompositions with measurements from other LHC instruments allowed different validations. (author)

  2. Electron beam diagnostics study

    International Nuclear Information System (INIS)

    Garganne, P.

    1989-08-01

    This paper summarizes the results of a study on beam diagnostics, using carbon wire scanners and optical transition radiation (DTR) monitors. The main consideration consists in the material selection, taking their thermal properties and their effect on the beam into account [fr

  3. Atomic Ferris wheel beams

    OpenAIRE

    Lembessis, Vasileios E.

    2017-01-01

    We study the generation of atom vortex beams in the case where an atomic wave-packet, moving in free space, is diffracted from a properly tailored light mask with a spiral transverse profile. We show how such a diffraction scheme could lead to the production of an atomic Ferris wheel beam.

  4. Atomic Ferris wheel beams

    Science.gov (United States)

    Lembessis, Vasileios E.

    2017-07-01

    We study the generation of atom vortex beams in the case where a Bose-Einstein condensate, released from a trap and moving in free space, is diffracted from a properly tailored light mask with a spiral transverse profile. We show how such a diffraction scheme could lead to the production of an atomic Ferris wheel beam.

  5. Ionization beam scanner

    CERN Multimedia

    CERN PhotoLab

    1973-01-01

    Inner structure of an ionization beam scanner, a rather intricate piece of apparatus which permits one to measure the density distribution of the proton beam passing through it. On the outside of the tank wall there is the coil for the longitudinal magnetic field, on the inside, one can see the arrangement of electrodes creating a highly homogeneous transverse electric field.

  6. Experimental study of the molecular beam destruction by beam-beam and beam-background scattering

    International Nuclear Information System (INIS)

    Bossel, U.; Dettleff, G.

    1974-01-01

    The extraction of flow properties related to the molecular motion normal to stream lines of an expanding gas jet from observed intensity profiles of supersonic beams is critically assessed. The perturbation of the profile curves by various effects is studied for a helium beam. Exponential laws appear to describe scattering effects to a satisfactory degree

  7. Electron beam transport

    International Nuclear Information System (INIS)

    Rudjak, Yu.V.; Vladyko, V.B.

    1993-01-01

    The electron beam transport in ion channel has been investigated. The influence of the external longitudinal magnetic field and self beam magnetic field on the charge neutralization process was defined. Beam head erosion under channel is curved or the availability of transverse external magnetic field was numerically simulated. The numerical investigation of the ion-hose instability was performed. The conditions, when as a result of ion-hose instability development may be coming out of the channel by beam tail, were founded. It was shown, that supplementary creation of plasma by electron beam and ions did not lead to the reduction of ion-hose instability. Sufficient slowing down of ion-hose instability development could be achieved if betatron length increased to impulse tail. In the case of a weak initial nonsymmetrical perturbation, sausage instability was investigated. Numerical simulation showed that this instability could lead to beam radius increasing in order. The electron beam guiding by low conductive plasma channel was considered. The attractive force of beam to this channel under nonsymmetrical injection was defined analytically

  8. Durnin-Whitney beams

    Science.gov (United States)

    de Jesús Cabrera-Rosas, Omar; Espíndola-Ramos, Ernesto; Alejandro Juárez-Reyes, Salvador; Julián-Macías, Israel; Ortega-Vidals, Paula; Rickenstorff-Parrao, Carolina; Silva-Ortigoza, Gilberto; Silva-Ortigoza, Ramón; Sosa-Sánchez, Citlalli Teresa

    2017-05-01

    The aim of the present work is to define a Durnin-Whitney beam as a nondiffracting beam such that its associated caustic locally only has singularities of the fold and cusp types. Since the caustic is structurally stable then the intensity pattern of this beam is also stable and this property is what makes its definition and its theoretical and experimental study worthwhile. These properties are important in applications such as uniform optical drilling in waveguides and communications through weak turbulent atmosphere. We find that in accordance with Whitney's theorem on the stability of maps from a two-dimensional manifold to a two-dimensional manifold the phase g({{Φ }}), of the complex function A({{Φ }}) characterizing the beam, locally is given by g({{Φ }})=a{{Φ }} for a fold and g({{Φ }})=b{{{Φ }}}2 for a cusp. This result implies that the Bessel beam of order zero is not stable and that any other Bessel beam is stable because locally it has a caustic of fold type. Finally, we present an example of a Durnin-Whitney beam given by g({{Φ }})=m{{Φ }}+b{{{Φ }}}2, which is a natural generalization of the Bessel beam of order m with a singularity of cusp ridge type.

  9. Dosimetry of pion beams

    International Nuclear Information System (INIS)

    Dicello, J.F.

    1975-01-01

    Negative pion beams are probably the most esoteric and most complicated type of radiation which has been suggested for use in clinical radiotherapy. Because of the limited availability of pion beams in the past, even to nuclear physicists, there exist relatively fewer basic data for this modality. Pion dosimetry is discussed

  10. Beaming teaching application

    DEFF Research Database (Denmark)

    Markovic, Milos; Madsen, Esben; Olesen, Søren Krarup

    2012-01-01

    BEAMING is a telepresence research project aiming at providing a multimodal interaction between two or more participants located at distant locations. One of the BEAMING applications allows a distant teacher to give a xylophone playing lecture to the students. Therefore, rendering of the xylophon...

  11. Beam director design report

    International Nuclear Information System (INIS)

    Younger, F.C.

    1986-08-01

    A design and fabrication effort for a beam director is documented. The conceptual design provides for the beam to pass first through a bending and focusing system (or ''achromat''), through a second achromat, through an air-to-vacuum interface (the ''beam window''), and finally through the vernier steering system. Following an initial concept study for a beam director, a prototype permanent magnet 30 0 beam-bending achromat and prototype vernier steering magnet were designed and built. In volume II, copies are included of the funding instruments, requests for quotations, purchase orders, a complete set of as-built drawings, magnetic measurement reports, the concept design report, and the final report on the design and fabrication project

  12. Vortices in Gaussian beams

    CSIR Research Space (South Africa)

    Roux, FS

    2009-01-01

    Full Text Available , t0)} = P(du, dv) {FR{g(u, v, t0)}} Replacement: u→ du = t− t0 i2 ∂ ∂u′ v → dv = t− t0 i2 ∂ ∂v′ CSIR National Laser Centre – p.13/30 Differentiation i.s.o integration Evaluate the integral over the Gaussian beam (once and for all). Then, instead... . Gaussian beams with vortex dipoles CSIR National Laser Centre – p.2/30 Gaussian beam notation Gaussian beam in normalised coordinates: g(u, v, t) = exp ( −u 2 + v2 1− it ) u = xω0 v = yω0 t = zρ ρ = piω20 λ ω0 — 1/e2 beam waist radius; ρ— Rayleigh range ω ω...

  13. Bunched beam diagnostics

    International Nuclear Information System (INIS)

    Siemann, R.H.

    1989-01-01

    There is a remarkable diversity in the field of accelerator physics. Look at the proceedings of any conference. Papers range from Hamiltonian dynamics to the latest improvements of performance in accelerator X to the engineering of specialized equipment. Beam diagnostics is somewhere in the middle of this. Diagnostic instruments make the connection between theories and observations, and the capabilities of these instruments influence strongly our ability to improve performance. The gave a series of lectures in 1987 on the general topic of Principles of Beam Observation. The emphasis was on frequency domain analysis of beam generated signals in storage rings, and that is the subject of this paper. The goal is to connect spectrum analyzer observations to what the beam is doing. In addition, understanding beam spectra is essential for understanding coherent effects and instabilities in storage rings, and this is discussed extensively. 23 figures, 4 tables

  14. Atom beam source

    International Nuclear Information System (INIS)

    Franks, J.

    1984-01-01

    Ion beam V etching may give rise to undesirable effects such as uneven erosion and ion migration in dielectrics, even when the surface is neutralized by electron flooding. The effects appear due to a remaining charge imbalance on a microscopic scale, which is absent when bombarding with an uncharged beam. Saddle field sources provide a convenient means of producing energetic neutral beams of inert and reactive gases (which may be dissociated into radicals). The construction and characteristics of the sources are described and a mechanism of internal neutralization proposed. Evidence is given that uncharged beams introduce less damage than equivalent ion beams. Disruptive effects may be initiated by charge accumulation or possibly by neutralization processes which occur when ions closely approach the target surface. (author)

  15. Ion beam monitoring

    International Nuclear Information System (INIS)

    McKinney, C.R.

    1980-01-01

    An ion beam analyzer is specified, having an ion source for generating ions of a sample to be analyzed, means for extracting the sample ions, means for focusing the sample ions into a beam, separation means positioned along the ion beam for selectively deflecting species of ions, and means for detecting the selected species of ions. According to the specification, the analyzer further comprises (a) means for disabling at least a portion of the separation means, such that the ion beam from the source remains undeflected; (b) means located along the path of the undeflected ion beam for sensing the sample ions; and (c) enabling means responsive to the sensing means for automatically re-enabling the separation means when the sample ions reach a predetermined intensity level. (author)

  16. Beam director design report

    Energy Technology Data Exchange (ETDEWEB)

    Younger, F.C.

    1986-08-01

    A design and fabrication effort for a beam director is documented. The conceptual design provides for the beam to pass first through a bending and focusing system (or ''achromat''), through a second achromat, through an air-to-vacuum interface (the ''beam window''), and finally through the vernier steering system. Following an initial concept study for a beam director, a prototype permanent magnet 30/sup 0/ beam-bending achromat and prototype vernier steering magnet were designed and built. In volume II, copies are included of the funding instruments, requests for quotations, purchase orders, a complete set of as-built drawings, magnetic measurement reports, the concept design report, and the final report on the design and fabrication project. (LEW)

  17. Survey of beam-beam limitations

    International Nuclear Information System (INIS)

    Courant, E.; Cornacchia, M.; Donald, M.M.R.; Evans, L.R.; Tazzari, S.; Wilson, E.J.N.

    1979-01-01

    The effect of beam-beam interaction is known to limit the luminosity of electron-positron storage rings and will, no doubt, limit the proton-antiproton collision scheme for the SPS. While theorists are struggling to explain this phenomenon it is more instructive to list their failures than their rather limited successes, in the hope that experiments may emerge which will direct their endeavors. The search for a description of a nonlinear system as it approaches the limit in which ordered motion breaks down, is the nub of the problem. It has engaged many fine mathematical intellects for decades and will no doubt continue to do so long after ISABELLE, the p antip and LEP are past achievements. Empirical scaling laws are emerging which relate electron machines to each other but their extrapolation to proton machines remain a very speculative exercise. Experimental data on proton limits is confined to one machine, the ISR, which does not normally suffer the beam-beam effect and where it must be artificially induced or simulated. This machine is also very different in important ways from the p antip collider. The gloomy picture which has emerged recently is that the fixed limits which were conventionally assumed for proton and electron machines can only be said to be valid for the machines which engendered them - the best guess that could be made at the time. They are very difficult to extrapolate to other sets of parameters

  18. Beam-width spreading of vortex beams in free space

    Science.gov (United States)

    Wang, Weiwei; Li, Jinhong; Duan, Meiling

    2018-01-01

    Based on the extended Huygens-Fresnel principle and the definition of second-order moments of the Wigner distribution function, the analytical expression for the beam-width spreading of Gaussian Schell-model (GSM) vortex beams in free space are derived, and used to study the influence of beam parameters on the beam-width spreading of GSM vortex beams. With the increment of the propagation distance, the beam-width spreading of GSM vortex beams will increase; the bigger the topological charge, spatial correlation length, wavelength and waist width are, the smaller the beam-width spreading is.

  19. Electron Beam Lithography

    Science.gov (United States)

    Harriott, Lloyd R.

    1997-04-01

    Electron beams have played a significant role in semiconductor technology for more than twenty years. Early electron beam machines used a raster scanned beam spot to write patterns in electron-sensitive polymer resist materials. The main application of electron beam lithography has been in mask making. Despite the inherently high spatial resolution and wide process margins of electron beam lithography, the writing rate for semiconductor wafers has been too slow to be economically viable on a large scale. In the late 1970's, variable shape electron beam writing was developed, projecting a rectangular beam whose size can be varied for each "shot" exposure of a particular pattern, allowing some integrated circuits to be made economically where a variety of "customized" patterns are desired. In the cell or block projection electron beam exposure technique, a unit cell of a repetitive pattern is projected repeatedly to increase the level of parallelism. This can work well for highly repetitive patterns such as memory chips but is not well suited to complex varying patterns such as microprocessors. The rapid progress in the performance of integrated circuits has been largely driven by progress in optical lithography, through improvements in lens design and fabrication as well as the use of shorter wavelengths for the exposure radiation. Due to limitations from the opacity of lens and mask materials, it is unlikely that conventional optical printing methods can be used at wavelengths below 193 nm or feature sizes much below 180 nm. One candidate technology for a post-optical era is the Scattering with Angular Limitation Projection Electron-beam Lithography (SCALPEL) approach, which combines the high resolution and wide process latitude inherent in electron beam lithography with the throughput of a parallel projection system. A mask consisting of a low atomic number membrane and a high atomic number pattern layer is uniformly illuminated with high energy (100 ke

  20. High bandwidth beam current monitor

    International Nuclear Information System (INIS)

    Baltrusaitis, R.M.; Ekdahl, C.A.; Cooper, R.G.; Peterson, E.; Warn, C.E.

    1993-01-01

    A stripline directional coupler beam current monitor capable of measuring the time structure of a 30-ps electron beam bunch has been developed. The time response performance of the monitor compares very well with Cherenkov light produced in quartz by the electron beam. The four-pickup monitor is now used on a routine basis for measuring the beam duration, tuning for optimized beam bunching, and centering the bunch in the beam pipe

  1. Beam-beam limit in e+e- circular colliders

    International Nuclear Information System (INIS)

    Ohmi, K.; Tawada, M.; Kamada, S.; Oide, K.; Cai, Y.; Qiang, J.

    2004-01-01

    Beam-beam effects limit the luminosity of circular colliders. Once the bunch population exceeds a threshold, the luminosity increases at a slower rate. This phenomenon is called the beam-beam limit. Onset of the beam-beam limit has been analyzed with various simulation methods based on the weak-strong and strong-strong models. We have observed that an incoherent phenomenon is mainly concerned in the beam-beam limit. The simulation have shown that equilibrium distributions of the two colliding beams are distorted from Gaussians when the luminosity is limited. The beam-beam limit is estimated to be ξ∼0.1 for a B factory with damping time of several thousand turns

  2. 3D Terahertz Beam Profiling

    DEFF Research Database (Denmark)

    Pedersen, Pernille Klarskov; Strikwerda, Andrew; Jepsen, Peter Uhd

    2013-01-01

    We present a characterization of THz beams generated in both a two-color air plasma and in a LiNbO3 crystal. Using a commercial THz camera, we record intensity images as a function of distance through the beam waist, from which we extract 2D beam profiles and visualize our measurements into 3D beam...... profiles. For the two-color air-plasma, we measure a conical beam profile that is focused to a bell-shape at the beam waist, whereas we observe a Gaussian beam profile for the THz beam generated from the LiNbO3 crystal....

  3. Luminescent beam stop

    Energy Technology Data Exchange (ETDEWEB)

    Bryant, Diane; Morton, Simon A.

    2017-10-25

    This disclosure provides systems, methods, and apparatus related to beam stops. In one aspect, a device comprises a luminescent material, a beam stop plate, and an optical fiber. The luminescent material is a parallelepiped having a first side and a second side that are squares and having a third side that is a rectangle or a square. The first side and the second side are perpendicular to the third side. The beam stop plate is attached to the first side of the luminescent material. The optical fiber has a first end and a second end, with the first end of the optical fiber attached to the third side of the luminescent material.

  4. WORKSHOP: Crystalline beams

    International Nuclear Information System (INIS)

    Anon.

    1989-01-01

    Following pioneer work by specialists at the Soviet Novosibirsk Laboratory some ten years ago, interest developed in the possibility of 'freezing' ion beams in storage rings by pushing cooling (to smooth out beam behaviour) to its limits, the final goal being to lock the ions into a neat crystal pattern. After advances by groups working on laser cooled ions in traps, and with several cooling rings now in operation, a workshop on crystalline ion beams was organized recently by the GSI (Darmstadt) Laboratory and held at Wertheim in Germany

  5. Mass spectrometer beam monitor

    International Nuclear Information System (INIS)

    McKinney, C.R.

    1980-01-01

    Improved apparatus and system were developed for determining the field desorption characteristics of a sample prior to field desorption mass spectrometry. A portion of the ion beam from the ion source is disabled so that it is undeflected in the beam analyzer. When sample ions are detected by a sensor in this portion of the beam it is then allowed to be deflected and the mass analysis occurs. Thus the source position, temperature and electric field strength can be varied until ions are produced from the sample and the field desorption characteristics can be determined. The source characteristics can be varied either automatically or manually. (DN)

  6. Is every quasar beamed?

    Science.gov (United States)

    Barthel, Peter D.

    1989-01-01

    A companion paper (Barthel et al.) reports the discovery of superluminal motion in the core of 4C 34.47, the largest known quasi-stellar radio source. Superluminal motion, the apparent continuity of small- and large-scale one-sided radio jets, and the recently established depolarization asymmetry in luminous quasars find a natural explanation in the effects of relativistic beaming. In the frameworkof of this relativistic beaming model, the available data imply that all radio-loud quasars are beamed toward the earth. Powerful radio galaxies may well form the unbeamed parent population. Radio-quiet QSOs and powerful infrared galaxies can be unified using similar orientation effects.

  7. Secondary beams at GANIL

    International Nuclear Information System (INIS)

    Doubre, H.

    1992-01-01

    GANIL, a user's facility since 1983, can deliver a broad spectrum of heavy-ion beams, from He to U, to well-equipped experimental areas. Their very large intensities are to be exploited to produce secondary beams, either using the fragmentation method (beams at energy per nucleon larger than 30 MeV/u), or the ISOL method. With the latter one, these ions have to be re-accelerated. The project of a cyclotron as a post-accelerator is described. (author) 11 refs.; 7 figs.; 3 tabs

  8. ICFA Beam Dynamics Newsletter

    Energy Technology Data Exchange (ETDEWEB)

    Pikin, A. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2017-11-21

    Electron beam ion sources technology made significant progress since 1968 when this method of producing highly charged ions in a potential trap within electron beam was proposed by E. Donets. Better understanding of physical processes in EBIS, technological advances and better simulation tools determined significant progress in key EBIS parameters: electron beam current and current density, ion trap capacity, attainable charge states. Greatly increased the scope of EBIS and EBIT applications. An attempt is made to compile some of EBIS engineering problems and solutions and to demonstrate a present stage of understanding the processes and approaches to build a better EBIS.

  9. Neutral particle beam intensity controller

    Science.gov (United States)

    Dagenhart, W.K.

    1984-05-29

    The neutral beam intensity controller is based on selected magnetic defocusing of the ion beam prior to neutralization. The defocused portion of the beam is dumped onto a beam dump disposed perpendicular to the beam axis. Selective defocusing is accomplished by means of a magnetic field generator disposed about the neutralizer so that the field is transverse to the beam axis. The magnetic field intensity is varied to provide the selected partial beam defocusing of the ions prior to neutralization. The desired focused neutral beam portion passes along the beam path through a defining aperture in the beam dump, thereby controlling the desired fraction of neutral particles transmitted to a utilization device without altering the kinetic energy level of the desired neutral particle fraction. By proper selection of the magnetic field intensity, virtually zero through 100% intensity control of the neutral beam is achieved.

  10. Electron beam curing paint

    International Nuclear Information System (INIS)

    Maruyama, Tsutomu

    1991-04-01

    Electron beam curing (EBC) type paint is paint that is specially prepared so that it can be cured and dried by electron beam irradiation. Electron beam irradiation achieves hardly any curing and drying of ordinary normal-temperature drying type paint or heat-drying type paint. The main type of paint in which an electron beam produces a curing reaction is one in which a radical polymerization reaction takes place under irradiation. The use of this EBC painting - drying system has been considered for a variety of fields since it has a number of special features such as the fact that the paint dries instantaneously, no heat is applied and no solvent is used. (Author)

  11. Electron Beam Ion Sources

    CERN Document Server

    Zschornacka, G.; Thorn, A.

    2013-12-16

    Electron beam ion sources (EBISs) are ion sources that work based on the principle of electron impact ionization, allowing the production of very highly charged ions. The ions produced can be extracted as a DC ion beam as well as ion pulses of different time structures. In comparison to most of the other known ion sources, EBISs feature ion beams with very good beam emittances and a low energy spread. Furthermore, EBISs are excellent sources of photons (X-rays, ultraviolet, extreme ultraviolet, visible light) from highly charged ions. This chapter gives an overview of EBIS physics, the principle of operation, and the known technical solutions. Using examples, the performance of EBISs as well as their applications in various fields of basic research, technology and medicine are discussed.

  12. Final focus test beam

    International Nuclear Information System (INIS)

    1991-03-01

    This report discusses the following: the Final Focus Test Beam Project; optical design; magnets; instrumentation; magnetic measurement and BPM calibration; mechanical alignment and stabilization; vacuum system; power supplies; control system; radiation shielding and personnel protection; infrastructure; and administration

  13. HIRENASD Beam FEM

    Data.gov (United States)

    National Aeronautics and Space Administration — This contains attempts to create BEAM FEM model. I have started a Blog to discuss this... please put your comments there and I will attempt to keep everything...

  14. Single Beam Holography.

    Science.gov (United States)

    Chen, Hsuan; Ruterbusch, Paul H.

    1979-01-01

    Discusses how holography can be used as part of undergraduate physics laboratories. The authors propose a single beam technique of holography, which will reduce the recording scheme as well as relax the isolation requirements. (HM)

  15. Beam-beam diagnostics from closed-orbit distortion

    Energy Technology Data Exchange (ETDEWEB)

    Furman, M.; Chin, Y.H.; Eden, J. [Lawrence Berkeley Lab., CA (United States); Kozanecki, W. [DAPNIA/SPP, CEN Saclay Gif-sur-Yvette, (FR)]|[Stanford Linear Accelerator Center, Menlo Park, CA (United States); Tennyson, J.; Ziemann, V. [Stanford Linear Accelerator Center, Menlo Park, CA (United States)

    1992-07-01

    We study the applicability of beam-beam deflection techniques as a tuning tool for asymmetric B factories, focusing on PEP-II as an example. Assuming that the closed orbits of the two beams are separated vertically at the interaction point by a local orbit bump that is nominally closed, we calculate the residual beam orbit distortions due to the beam-beam interaction. Difference orbit measurements, performed at points conveniently distant from the interaction point (IP), provide distinct signatures that can be used to maintain the beams in collision and perform detailed optical diagnostics at the IP. A proposal to test this method experimentally at the TRISTAN ring is briefly discussed.

  16. SPIDER beam dump as diagnostic of the particle beam

    Energy Technology Data Exchange (ETDEWEB)

    Zaupa, M., E-mail: matteo.zaupa@igi.cnr.it; Sartori, E. [Università degli Studi di Padova, Via 8 Febbraio 2, Padova 35122 (Italy); Consorzio RFX, Corso Stati Uniti 4, Padova 35127 (Italy); Dalla Palma, M.; Brombin, M.; Pasqualotto, R. [Consorzio RFX, Corso Stati Uniti 4, Padova 35127 (Italy)

    2016-11-15

    The beam power produced by the negative ion source for the production of ion of deuterium extracted from RF plasma is mainly absorbed by the beam dump component which has been designed also for measuring the temperatures on the dumping panels for beam diagnostics. A finite element code has been developed to characterize, by thermo-hydraulic analysis, the sensitivity of the beam dump to the different beam parameters. The results prove the capability of diagnosing the beam divergence and the horizontal misalignment, while the entity of the halo fraction appears hardly detectable without considering the other foreseen diagnostics like tomography and beam emission spectroscopy.

  17. Beam-beam simulation of Möbius-modified CESR

    Science.gov (United States)

    Talman, R.; Malitsky, N.; Koyama, T.

    1997-05-01

    Colliding beam experiments at CESR with beams made round by running on the coupling resonance have been performed,(E. Young et al.), abstract, this conference and runs are planned with the beams made round by Möbius modification.(R. Talman, Phys. Rev. Lett. 74), 1590, (1995) Performance in these configurations has been simulated using TEAPOT++ tracking, map generation, stochastic, and beam-beam modules within the Unified Accelerator Libraries(N. Malitsky et al.), abstract, this conference The true CESR lattice including sextupoles and element apertures is used. Outputs from the calculation include beam profile modification, tune optimization, maximum luminosity, and (with extrapolation) beam lifetimes.

  18. Beam-beam simulations: dynamical effects and beam-beam limit for LEP3

    CERN Document Server

    Ohmi, K

    2012-01-01

    Beam-beam simulations are reported for LEP3 and TLEP-H, including a rough tune scan. The results suggest that to achieve the design luminosity in LEP3, 10% higher bunch population may be necessary, while TLEP-H can achieve the design performance without any changes. The simulations indicate that the large synchrotron tune, in conjunction with a large hourglass effect, degrades the luminosity performance. This talk was given at CERN on 4 December 2012.

  19. Betatrons with kiloampere beams

    International Nuclear Information System (INIS)

    Peterson, J.M.

    1982-11-01

    Although the magnetic-induction method of acceleration used in the betatron is inherently capable of accelerating intense particle beams to high energy, many beam-instability questions arise when beams in the kilo-ampere range are considered. The intense electromagnetic fields produced by the beam, and by the image currents and charges induced in the surrounding walls, can produce very disruptive effects. Several unstable modes of collective oscillation are possible; the suppression of any one of them usually involves energy spread for Landau damping and careful design of the electrical character of the vacuum chamber. The various design criteria are often mutually incompatible. Space-charge detuning can be severe unless large beam apertures and high-energy injection are used. In order to have an acceptably low degree of space-charge detuning in the acceleration of a 10-kilo-ampere electron beam, for example, an injection energy on the order of 50 MeV seems necessary, in which case the forces due to nearby wall images can have a larger effect than the internal forces of the beam. A method of image compensation was invented for reducing the net image forces; it serves also to decrease the longitudinal beam impedance and thus helps alleviate the longitudinal instability as well. In order to avoid the ion-electron collective instability a vacuum in the range of 10 - 8 torr is required for an acceleration time of 1 millisecond. A multi-ring betatron system using the 50-MeV Advanced Test Accelerator at LLNL as an injector was conceptually designed

  20. LHCb: Beam Pipe portrait

    CERN Multimedia

    LHCb, Collaboration

    2005-01-01

    The proton beams circulate in the accelerator in Ultra High Vacuum to make them interact only with each other when colliding at the interaction point. A special beam pipe "holds" the vacuum where they pass through the LHCb detector: it has to be mechanically very strong to stand the difference in pressure between the vacuum inside it and the air in the cavern but also be as transparent as possible for the particles originating in the proton−proton collisions.

  1. LHCb: Beam Pipe

    CERN Multimedia

    LHCb, Collaboration

    2005-01-01

    The proton beams circulate in the accelerator in Ultra High Vacuum to make them interact only with each other when colliding at the interaction point. A special beam pipe "holds" the vacuum where they pass through the LHCb detector:it has to be mechanically very strong to stand the difference in pressure between the vacuum inside it and the air in the cavern but also be as transparent as possible for the particles originating in the proton−proton collisions.

  2. PARTICLE BEAMS: Frontier course

    International Nuclear Information System (INIS)

    Anon.

    1987-01-01

    Driven by the quest for higher energies and optimal physics conditions, the behaviour of particle beams in accelerators and storage rings is the subject of increasing attention. Thus the second course organized jointly by the US and CERN Accelerator Schools looked towards the frontiers of particle beam knowledge. The programme held at South Padre Island, Texas, from 23-29 October attracted 125 participants including some 35 from Europe

  3. LHC First Beam 2008

    CERN Multimedia

    Tuura, L

    2008-01-01

    The CMS Centre played a major part in the LHC First Beam Event on September 10th 2008: it was a central point for CMS, hosting journalists from all over the world and providing live link-ups to collaborating institutes as well as, of course, monitoring events as they happened at Point 5. It was also a venue for celebration as the beam completed circuits of the LHC in both directions, passing successfully through the detector (Courtesy of Lassi Tuura)

  4. Terascale Beam-Beam Simulations for Tevatron, RHIC and LHC

    Energy Technology Data Exchange (ETDEWEB)

    Qiang, J.

    2005-05-16

    In this paper, we report on recent advances in terascale simulations of the beam-beam interaction in Tevatron, RHIC and LHC.Computational methods for self consistent calculation of beam-beam forces are reviewed. New method for solving the two-dimensional Poisson equation with open boundary conditions is proposed and tested. This new spectral-finite difference method is a factor of four faster than the widely used FFT based Green function method for beam-beam interaction on axis. We also present applications to the study of antiproton losses during the injection stage at Tevatron, to the study of multiple bunch coherent beam-beam modes at RHIC, and to the study of beam-beam driven emittance growth at LHC.

  5. Terascale Beam-Beam Simulations for Tevatron, RHIC and LHC

    International Nuclear Information System (INIS)

    Qiang, J.

    2005-01-01

    In this paper, we report on recent advances in terascale simulations of the beam-beam interaction in Tevatron, RHIC and LHC.Computational methods for self consistent calculation of beam-beam forces are reviewed. New method for solving the two-dimensional Poisson equation with open boundary conditions is proposed and tested. This new spectral-finite difference method is a factor of four faster than the widely used FFT based Green function method for beam-beam interaction on axis. We also present applications to the study of antiproton losses during the injection stage at Tevatron, to the study of multiple bunch coherent beam-beam modes at RHIC, and to the study of beam-beam driven emittance growth at LHC

  6. Transverse equilibria in linear collider beam-beam collisions

    International Nuclear Information System (INIS)

    Rosenzweig, J.B.; Chen, Pisin

    1991-01-01

    It has been observed in simulations of the beam-beam interaction in linear colliders that a near equilibrium pinched state of the colliding beams develops when the disruption parameter is large (D much-gt 1). In this state the beam transverse density distributions are peaked at center, with long tails. The authors present here an analytical model of the equilibrium approached by the beams, that of a generalized Bennett pinch which develops through collisionless damping due to the strong nonlinearity of the beam-beam interaction. In order to calculate the equilibrium pinched beam size, an estimation of the rms emittance growth is made which takes into account the partial adiabaticity of the collision. This pinched beam size is used to derive the luminosity enhancement factors whose scaling is in agreement with the simulation results for both D and thermal factor A = σ z /β * large, and explains the previously noted cubic relationship between round and flat beam enhancement factors

  7. Beam structure studies of low-energy ion beams

    Science.gov (United States)

    Saadatmand, K.; Schneider, J. D.; Geisik, C.; Stevens, R. R.

    1991-05-01

    The ion beam structure at various axial positions along the beam-transport line has been monitored and studied utilizing a fluor screen and a video camera. The fluor material is aluminum oxide that is plasma-jet sprayed onto the surface of an aluminum or a water-cooled copper substrate. The visual representation of the beam structure is digitized and enhanced through use of false-color coding and displayed on a TV monitor for the on-line viewing by the experimentalist. Digitized video signals are stored for further off-line processing and extracting more information about the beam, such as beam profiles. This inexpensive and effective diagnostic enables the experimentalist to observe the real-time beam response (such as evolution of the beam structure, shifts in the beam intensity at various spatial locations within the beam perimeter, and shifts in the beam center and position) to parameter changes.

  8. Photon beam position monitor

    Science.gov (United States)

    Kuzay, Tuncer M.; Shu, Deming

    1995-01-01

    A photon beam position monitor for use in the front end of a beamline of a high heat flux and high energy photon source such as a synchrotron radiation storage ring detects and measures the position and, when a pair of such monitors are used in tandem, the slope of a photon beam emanating from an insertion device such as a wiggler or an undulator inserted in the straight sections of the ring. The photon beam position monitor includes a plurality of spaced blades for precisely locating the photon beam, with each blade comprised of chemical vapor deposition (CVD) diamond with an outer metal coating of a photon sensitive metal such as tungsten, molybdenum, etc., which combination emits electrons when a high energy photon beam is incident upon the blade. Two such monitors are contemplated for use in the front end of the beamline, with the two monitors having vertically and horizontally offset detector blades to avoid blade "shadowing". Provision is made for aligning the detector blades with the photon beam and limiting detector blade temperature during operation.

  9. Polarized proton beams

    International Nuclear Information System (INIS)

    Roser, T.

    1995-01-01

    The acceleration of polarized proton beams in circular accelerators is complicated by the presence of numerous depolarizing spin resonances. Careful and tedious minimization of polarization loss at each of these resonances allowed acceleration of polarized proton beams up to 22 GeV. It has been the hope that Siberian Snakes, which are local spin rotators inserted into ring accelerators, would eliminate these resonances and allow acceleration of polarized beams with the same ease and efficiency that is now routine for unpolarized beams. First tests at IUCF with a full Siberian Snake showed that the spin dynamics with a Snake can be understood in detail. The author now has results of the first tests of a partial Siberian Snake at the AGS, accelerating polarized protons to an energy of about 25 GeV. These successful tests of storage and acceleration of polarized proton beams open up new possibilities such as stored polarized beams for internal target experiments and high energy polarized proton colliders

  10. Ion Accelerator Merges Several Beams

    Science.gov (United States)

    Aston, G.

    1984-01-01

    Intense ion beam formed by merging multiple ion beamlets into one concentrated beam. Beamlet holes in graphite screen and focusing grids arranged in hexagonal pattern. Merged beam passes through single hole in each of aluminum accelerator and decelerator grids. Ion extraction efficiency, beam intensity, and focusing improved.

  11. Beam abort detection of SSRF

    International Nuclear Information System (INIS)

    Feng Chenxia; Zhou Weimin; Leng Yongbin

    2010-01-01

    Beam abort signal is a timing signal of the SSRF (Shanghai Synchrotron Radiation Facility) storage ring. It is used to synchronize BPM processor Libera logging beam position data to identify beam abort source and improve the stability of accelerator. The concept design and engineering design of beam abort trigger module are introduced in this paper, and lab test results of this module using RF signal source also presented. Online beam test results show that this module has achieved design goal, could be used to log beam position data before beam abort. (authors)

  12. Beam-beam observations in the Relativistic Heavy Ion Collider

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Y. [Brookhaven National Laboratory (BNL), Upton, NY (United States); Fischer, W. [Brookhaven National Laboratory (BNL), Upton, NY (United States); White, S. [Brookhaven National Laboratory (BNL), Upton, NY (United States)

    2015-06-24

    The Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory has been operating since 2000. Over the past decade, thanks to the continuously increased bunch intensity and reduced β*s at the interaction points, the maximum peak luminosity in the polarized proton operation has been increased by more than two orders of magnitude. In this article, we first present the beam-beam observations in the previous RHIC polarized proton runs. Then we analyze the mechanisms for the beam loss and emittance growth in the presence of beam-beam interaction. The operational challenges and limitations imposed by beam-beam interaction and their remedies are also presented. In the end, we briefly introduce head-on beam-beam compensation with electron lenses in RHIC.

  13. Beam Profile Measurement in MTA Beam Line for High Pressure RF Cavity Beam Test

    International Nuclear Information System (INIS)

    Jana, M.R.; Bross, A.; Chung, M.; Greer, S.; Johnstone, C.; Kobilarcik, T.; Koizumi, G.; Leonova, M.; Moretti, A.; Popovic, M.; Schwartz, T.

    2012-01-01

    Recent High Pressure RF (HPRF) cavity experiment at MuCool Test Area (MTA) has used 400 MeV Linac proton beam to study the beam loading effect. When the energetic proton beam passes through the cavity, it ionizes the inside gas and produces the electrons. These electrons consume RF power inside the cavity. Number of electrons produced per cm inside the cavity (at 950 psi Hydrogen gas) per incident proton is ∼ 1200. The measurement of beam position and profile are necessary. MTA is flammable gas (Hydrogen) hazard zone so we have developed a passive beam diagnostic instrument using Chromox-6 scintillation screen and CCD camera. This paper presents quantitative information about beam position and beam profile. Neutral density filter was used to avoid saturation of CCD camera. Image data is filtered and fitted with Gaussian function to compute the beam size. The beam profile obtained from scintillation screen shall be compared with multi-wire beam profile.

  14. ICFA Beam Dynamics Newsletter

    Energy Technology Data Exchange (ETDEWEB)

    Ben-Zvi I.; Kuczewski A.; Altinbas, Z.; Beavis, D.; Belomestnykh,; Dai, J. et al

    2012-07-01

    The Collider-Accelerator Department at Brookhaven National Laboratory is building a high-brightness 500 mA capable Energy Recovery Linac (ERL) as one of its main R&D thrusts towards eRHIC, the polarized electron - hadron collider as an upgrade of the operating RHIC facility. The ERL is in final assembly stages, with injection commisioning starting in October 2012. The objective of this ERL is to serve as a platform for R&D into high current ERL, in particular issues of halo generation and control, Higher-Order Mode (HOM) issues, coherent emissions for the beam and high-brightness, high-power beam generation and preservation. The R&D ERL features a superconducting laser-photocathode RF gun with a high quantum efficiency photoccathode served with a load-lock cathode delivery system, a highly damped 5-cell accelerating cavity, a highly flexible single-pass loop and a comprehensive system of beam instrumentation. In this ICFA Beam Dynamics Newsletter article we will describe the ERL in a degree of detail that is not usually found in regular publications. We will discuss the various systems of the ERL, following the electrons from the photocathode to the beam dump, cover the control system, machine protection etc and summarize with the status of the ERL systems.

  15. Beam Time Accounting

    CERN Document Server

    Seitova, Diana

    2016-01-01

    ISOLDE is one of the leading research facilities in the field of nuclear physics. A proton beam with an energy 1.4 GeV coming from the Proton Synchrotron Booster (PSB) hits one of the targets at ISOLDE and produces Radioactive Ion Beams (RIBs). Then, the RIBs of interest is selected and delivered to the different experimental stations. In order to deliver the beam to the certain experimental station, the positions of the devices along the beamline should satisfy certain conditions. The purpose of this project is to define the conditions for the beam to pass through the different beamlines and to store the data about device’s status for later analysis and statistics, so it would be possible to know when the beam was used for different experiments. The data with the settings of the different devices is saved in the Timber database and the first steps for making virtual devices to compile the status of the beamlines were completed.

  16. Bringing up beams

    CERN Document Server

    Katarina Anthony

    2013-01-01

    Last month, commissioning began on CERN’s newest linear accelerator: Linac4. As the replacement machine for Linac2, Linac4 will take a negative hydrogen ion beam to a staggering 160 MeV. We check in to see how the Linac4 team is preparing its machine for its new role as the first link in the accelerator chain.   The Linac4 3 MeV beam line, with the ion source in the back, the RFQ in the middle and the chopping line in the front. On 14 November, members of the Linac4 collaboration and the CERN Operations Group were brought together for their first “real day” in the Linac4 Control Room. Together, they successfully accelerated their first hydrogen ion beam to 3 MeV. It was an exciting moment for everyone involved and marked the start of one of the most critical commissioning phases for the new accelerator. At the start of the Linac4 beam line sits the CERN-made Radio Frequency Quadrupole (RFQ). This vital piece of machinery takes the beam from 45 keV to 3 MeV in ju...

  17. A better beam quality

    CERN Multimedia

    CERN Bulletin

    2010-01-01

    Progress has been made on two fronts, providing physics data and preparing for higher intensities. Over the Whitsun weekend of May 22 to 24, 5 fills for physics provided almost 30 hours of stable colliding beams, all with bunch intensities around 2x1010 protons and at a β* of 2m. The first three of these fills were with 6 bunches per beam, giving 3 pairs of collisions in all experiments. For the other two fills, the number of bunches per beam was increased to 13, giving 8 pairs of colliding bunches, and for the first time luminosities were pushed above 1029 cm-2s-1, 2 orders of magnitude higher than first collisions in March. In between and after these physics fills, nominal bunches of 1011 protons were successfully ramped and brought into collision in ATLAS and CMS for the first time (not in stable beam conditions and without squeeze). Event rates seen by the experiments were in the expected range for these conditions. In the middle of this work, a short fill with beams of 7 nominal bunches was ...

  18. Paul Collier : Balancing beams

    CERN Multimedia

    2009-01-01

    As former head of AB Operations, Paul Collier and his group were in the ‘cockpit’ for the LHC’s maiden voyage - piloting the first beam around the ring. But now, as Head of the Beams Department, he will need his feet firmly on the ground in order to balance all the beam activities at CERN. "As Department Head, I’ll have less direct contact with the machines," Collier says with a hint of regret. "I’ll still obviously be very involved, but they won’t actually let me loose in front of the keyboard anymore!" As the new Head of the BE Department, Collier will be in charge of nearly 400 people, and will oversee all the beam activities, including the preparations for the longest period of beam operation in the history of CERN. In the new organization, the BE, TE and EN Departments have been grouped together in the Accelerator and Technology Sector. "‘Partnership’ is a key word for the three departments," says Collier. "The n...

  19. Lightweight HPC beam OMEGA

    Science.gov (United States)

    Sýkora, Michal; Jedlinský, Petr; Komanec, Jan

    2017-09-01

    In the design and construction of precast bridge structures, a general goal is to achieve the maximum possible span length. Often, the weight of individual beams makes them difficult to handle, which may be a limiting factor in achieving the desired span. The design of the OMEGA beam aims to solve a part of these problems. It is a thin-walled shell made of prestressed high-performance concrete (HPC) in the shape of inverted Ω character. The concrete shell with prestressed strands is fitted with a non-stressed tendon already in the casting yard and is more easily transported and installed on the site. The shells are subsequently completed with mild steel reinforcement and cores are cast in situ together with the deck. The OMEGA beams can also be used as an alternative to steel - concrete composite bridges. Due to the higher production complexity, OMEGA beam can hardly substitute conventional prestressed beams like T or PETRA completely, but it can be a useful alternative for specific construction needs.

  20. A beam position monitor for low current dc beams

    International Nuclear Information System (INIS)

    Adderley, P.; Barry, W.; Heefner, J.; Kloeppel, P.; Rossmanith, R.; Wise, M.; Jachim, S.

    1989-01-01

    The 4 GeV recirculating linac, CEBAF, if presently under construction and will produce a CW beam with average current between.1 and 200 μA. In order to measure beam position, the beam current will be amplitude modulated at a frequency of 10 MHz. The modulation is detected by an inductive loop type monitor with electronics sensitive only to the modulation frequency. The first test with beam from the CEBAF injector indicate that beam position can be measured with an accuracy of .1 mm at a modulated beam current of 1 μA. 1 ref., 6 figs., 1 tab

  1. Beam-beam studies for FCC-hh

    CERN Document Server

    AUTHOR|(CDS)2068329; Pieloni, Tatiana; Buffat, Xavier; Furuseth, Sondre Vik

    2017-01-01

    The Future Circular Collider hadron-hadron (FCC-hh) design study is currently exploring different IR design possibilities including round and flat optics or different crossing schemes. The present study intends to evaluate each scenario from the beam-beam effects point of view. In particular the single particle long term stability to maximize beam lifetimes and luminosity reach is used to quantify the differences. The impact of strong head on interactions on the beam quality and lifetime is addressed by means of GPU accelerated simulations code featuring a weak-strong 6-dimensional beam-beam interaction.

  2. High intensity beam dump for the Tevatron beam abort system

    International Nuclear Information System (INIS)

    Kidd, J.; Mokhov, N.; Murphy, T.; Palmer, M.; Toohig, T.; Turkot, F.; VanGinneken, A.

    1981-01-01

    The beam abort system proposed for the Fermilab Tevatron Accelerator will extract the proton beam from the ring in a single turn (approximately 20/mu/s) and direct it to an external beam dump. It is the function of the beam dump to absorb the unwanted beam and limit the escaping radiation to levels that are acceptable to the surrounding populace and apparatus. A beam dump that is expected to meet these requirements has been designed and constructed. Detailed design of the dump, including considerations leading to the choice of materials, are given. 6 refs

  3. Grazing incidence beam expander

    Energy Technology Data Exchange (ETDEWEB)

    Akkapeddi, P.R.; Glenn, P.; Fuschetto, A.; Appert, Q.; Viswanathan, V.K.

    1985-01-01

    A Grazing Incidence Beam Expander (GIBE) telescope is being designed and fabricated to be used as an equivalent end mirror in a long laser resonator cavity. The design requirements for this GIBE flow down from a generic Free Electron Laser (FEL) resonator. The nature of the FEL gain volume (a thin, pencil-like, on-axis region) dictates that the output beam be very small. Such a thin beam with the high power levels characteristic of FELs would have to travel perhaps hundreds of meters or more before expanding enough to allow reflection from cooled mirrors. A GIBE, on the other hand, would allow placing these optics closer to the gain region and thus reduces the cavity lengths substantially. Results are presented relating to optical and mechanical design, alignment sensitivity analysis, radius of curvature analysis, laser cavity stability analysis of a linear stable concentric laser cavity with a GIBE. Fabrication details of the GIBE are also given.

  4. Light Beam Generation

    DEFF Research Database (Denmark)

    2007-01-01

    The invention relates to a method and a system for synthesizing a set of controllable light beams by provision of a system for synthesizing a set of light beams, comprising a spatially modulated light source for generation of electromagnetic radiation with a set of replicas of a predetermined......(x-xs, y-ys), a Fourier transforming lens for Fourier transforming the electromagnetic radiation, a first spatial light modulator for phase shifting the Fourier transformed electromagnetic radiation with the phase -F(u, v) of S*, S* is the complex conjugate of the Fourier transformed symbol s, a Fourier...... transforming lens for Inverse Fourier transforming the spatially modulated radiation, whereby a set of light beams are formed propagating through the inverse Fourier plane (x', y') at desired positions (x's, y's), and a controller for controlling the position of a replica of the symbol, s, for movement...

  5. Is every quasar beamed?

    International Nuclear Information System (INIS)

    Barthel, P.D.

    1989-01-01

    A companion paper (Barthel et al.) reports the discovery of superluminal motion in the core of 4C 34.47, the largest known quasi-stellar radio source. Superluminal motion, the apparent continuity of small- and large-scale one-sided radio jets, and the recently established depolarization asymmetry in luminous quasars find a natural explanation in the effects of relativistic beaming. In the frameworkof of this relativistic beaming model, the available data imply that all radio-loud quasars are beamed toward the earth. Powerful radio galaxies may well form the unbeamed parent population. Radio-quiet QSOs and powerful infrared galaxies can be unified using similar orientation effects. 76 references

  6. Laser Beam Focus Analyser

    DEFF Research Database (Denmark)

    Nielsen, Peter Carøe; Hansen, Hans Nørgaard; Olsen, Flemming Ove

    2007-01-01

    the obtainable features in direct laser machining as well as heat affected zones in welding processes. This paper describes the development of a measuring unit capable of analysing beam shape and diameter of lasers to be used in manufacturing processes. The analyser is based on the principle of a rotating...... mechanical wire being swept through the laser beam at varying Z-heights. The reflected signal is analysed and the resulting beam profile determined. The development comprised the design of a flexible fixture capable of providing both rotation and Z-axis movement, control software including data capture...... and finally data analysis based on the ISO approach. The device was calibrated and tested on commercially available laser systems. It showed good reproducibility. It was the target to be able to measure CW lasers with a power up to 200 W, focused down to spot diameters in the range of 10µm. In order...

  7. Consistency checks in beam emission modeling for neutral beam injectors

    International Nuclear Information System (INIS)

    Punyapu, Bharathi; Vattipalle, Prahlad; Sharma, Sanjeev Kumar; Baruah, Ujjwal Kumar; Crowley, Brendan

    2015-01-01

    In positive neutral beam systems, the beam parameters such as ion species fractions, power fractions and beam divergence are routinely measured using Doppler shifted beam emission spectrum. The accuracy with which these parameters are estimated depend on the accuracy of the atomic modeling involved in these estimations. In this work, an effective procedure to check the consistency of the beam emission modeling in neutral beam injectors is proposed. As a first consistency check, at a constant beam voltage and current, the intensity of the beam emission spectrum is measured by varying the pressure in the neutralizer. Then, the scaling of measured intensity of un-shifted (target) and Doppler shifted intensities (projectile) of the beam emission spectrum at these pressure values are studied. If the un-shifted component scales with pressure, then the intensity of this component will be used as a second consistency check on the beam emission modeling. As a further check, the modeled beam fractions and emission cross sections of projectile and target are used to predict the intensity of the un-shifted component and then compared with the value of measured target intensity. An agreement between the predicted and measured target intensities provide the degree of discrepancy in the beam emission modeling. In order to test this methodology, a systematic analysis of Doppler shift spectroscopy data obtained on the JET neutral beam test stand data was carried out

  8. Beam dancer fusion device

    International Nuclear Information System (INIS)

    Maier, H.B.

    1984-01-01

    To accomplish fusion of two or more fusion fuel elements numerous minute spots of energy or laser light are directed to a micro target area, there to be moved or danced about by a precision mechanical controlling apparatus at the source of the laser light or electromagnetic energy beams, so that merging and coinciding patterns of light or energy beams can occur around the area of the fuel atoms or ions. The projecting of these merging patterns may be considered as target searching techniques to locate responsive clusters of fuel elements and to compress such elements into a condition in which fusion may occur. Computerized programming may be used

  9. Diamonds for beam instrumentation

    International Nuclear Information System (INIS)

    Griesmayer, Erich

    2013-01-01

    Diamond is perhaps the most versatile, efficient and radiation tolerant material available for use in beam detectors with a correspondingly wide range of applications in beam instrumentation. Numerous practical applications have demonstrated and exploited the sensitivity of diamond to charged particles, photons and neutrons. In this paper, a brief description of a generic diamond detector is given and the interaction of the CVD diamond detector material with protons, electrons, photons and neutrons is presented. Latest results of the interaction of sCVD diamond with 14 MeV mono-energetic neutrons are shown.

  10. Euroschool on Exotic Beams

    CERN Document Server

    Pfützner, Marek; The Euroschool on Exotic Beams, vol. IV

    2014-01-01

    This is the forth volume in a series of Lecture Notes based on the highly successful Euro Summer School on Exotic Beams. The aim of these notes is to provide a thorough introduction to radioactive ion-beam physics at the level of graduate students and young postdocs starting out in the field. Each volume covers a range of topics from nuclear theory to experiment and applications. Vol I has been published as LNP 651, Vol II has been published as LNP 700, and Vol. III has been published as LNP 764.

  11. The Colliding Beams Sequencer

    International Nuclear Information System (INIS)

    Johnson, D.E.; Johnson, R.P.

    1989-01-01

    The Colliding Beam Sequencer (CBS) is a computer program used to operate the pbar-p Collider by synchronizing the applications programs and simulating the activities of the accelerator operators during filling and storage. The Sequencer acts as a meta-program, running otherwise stand alone applications programs, to do the set-up, beam transfers, acceleration, low beta turn on, and diagnostics for the transfers and storage. The Sequencer and its operational performance will be described along with its special features which include a periodic scheduler and command logger. 14 refs., 3 figs

  12. GTK beam test 2017

    CERN Document Server

    Vostinic, Snezana

    2017-01-01

    The GTK is in operation at NA62 since 2014 and is among the few silicon pixel detectors performing 4D tracking. This summer, a beam test was conducted to study the phenomena determining the detector time resolution. The project described here contributed to the beam test preparation, data taking and data analyses. One of the main goals of the test was to understand the weight field contribution to the detector time resolution. This field is distorting the signal pulse shape at the edge of the pixel. Hence, to study this effect, the position of the hits inside the pixel has to be determined. An external telescope was therefore used for this purpose.

  13. Molecular beam epitaxy

    CERN Document Server

    Pamplin, Brian R

    1980-01-01

    Molecular Beam Epitaxy introduces the reader to the use of molecular beam epitaxy (MBE) in the generation of III-V and IV-VI compounds and alloys and describes the semiconductor and integrated optics reasons for using the technique. Topics covered include semiconductor superlattices by MBE; design considerations for MBE systems; periodic doping structure in gallium arsenide (GaAs); nonstoichiometry and carrier concentration control in MBE of compound semiconductors; and MBE techniques for IV-VI optoelectronic devices. The use of MBE to fabricate integrated optical devices and to study semicond

  14. The cooling of particle beams

    International Nuclear Information System (INIS)

    Sessler, A.M.

    1994-10-01

    A review is given of the various methods which can be employed for cooling particle beams. These methods include radiation damping, stimulated radiation damping, ionization cooling, stochastic cooling, electron cooling, laser cooling, and laser cooling with beam coupling. Laser Cooling has provided beams of the lowest temperatures, namely 1 mK, but only for ions and only for the longitudinal temperature. Recent theoretical work has suggested how laser cooling, with the coupling of beam motion, can be used to reduce the ion beam temperature in all three directions. The majority of this paper is devoted to describing laser cooling and laser cooling with beam coupling

  15. Investigation of the flat-beam model of the beam-beam interaction

    Directory of Open Access Journals (Sweden)

    Bjoern S. Schmekel

    2003-10-01

    Full Text Available At the interaction point of a storage ring collider each beam is subject to perturbations due to the electromagnetic field of the counterrotating beam. For flat beams, a well-known approximation models the beam by a current sheet which is uniform in the horizontal plane, restricting the particle motion to the vertical direction. In this classical model a water-bag beam distribution has been used to find working points and beam-beam tune shift parameters which lead to a stable beam distribution. We investigate the stability of a more realistic Gaussian equilibrium distribution. A linearized Vlasov equation written in action-angle variables is used to compute the radial and angular modes of a perturbation in two-dimensional phase space to first order in the displacement from the design trajectory. We find that the radial modes, which are often neglected, can have a stabilizing effect on the beam motion.

  16. Noncoaxial Bessel-Gauss beams.

    Science.gov (United States)

    Huang, Chaohong; Zheng, Yishu; Li, Hanqing

    2016-04-01

    We proposed a new family of noncoaxial Gauss-truncated Bessel beams through multiplying conventional symmetrical Bessel beams by a noncoaxial Gauss function. These beams can also be regarded as the exponential-truncated version of Bessel-Gauss beams since they can be transformed into the product of Bessel-Gauss beams and an exponential window function along a certain Cartesian axis. The closed-form solutions of the angular spectra and paraxial propagation of these beams were derived. These beams have asymmetrical intensity distributions and carry the same orbit angular momentum per photon as the corresponding Bessel-Gauss beams. While propagating along the z axis, the mth (m≠0) noncoaxial Bessel-Gauss beams rotate their intensity distributions and the mth-order vortex at the beam center has a transverse shift along the direction perpendicular to the offset axis. Depending on the product of the transverse scalar factor of the Bessel beams and the offset between the Gaussian window function and the center of the Bessel beams, the noncoaxial Bessel-Gauss beams can produce unit vortices with opposite signs in pairs during propagation.

  17. WORKSHOP: Beam cooling

    International Nuclear Information System (INIS)

    Anon.

    1994-01-01

    Cooling - the control of unruly particles to provide well-behaved beams - has become a major new tool in accelerator physics. The main approaches of electron cooling pioneered by Gersh Budker at Novosibirsk and stochastic cooling by Simon van der Meer at CERN, are now complemented by additional ideas, such as laser cooling of ions and ionization cooling of muons

  18. Neutrino beam plasma instability

    Indian Academy of Sciences (India)

    Abstract. We derive relativistic fluid set of equations for neutrinos and electrons from relativistic. Vlasov equations with Fermi weak interaction force. Using these fluid equations, we obtain a dis- persion relation describing neutrino beam plasma instability, which is little different from normal dispersion relation of streaming ...

  19. Neutrino beam plasma instability

    Indian Academy of Sciences (India)

    We derive relativistic fluid set of equations for neutrinos and electrons from relativistic Vlasov equations with Fermi weak interaction force. Using these fluid equations, we obtain a dispersion relation describing neutrino beam plasma instability, which is little different from normal dispersion relation of streaming instability.

  20. Ion-beam technologies

    Energy Technology Data Exchange (ETDEWEB)

    Fenske, G.R. [Argonne National Lab., IL (United States)

    1993-01-01

    This compilation of figures and diagrams reviews processes for depositing diamond/diamond-like carbon films. Processes addressed are chemical vapor deposition (HFCVD, PACVD, etc.), plasma vapor deposition (plasma sputtering, ion beam sputtering, evaporation, etc.), low-energy ion implantation, and hybrid processes (biased sputtering, IBAD, biased HFCVD, etc.). The tribological performance of coatings produced by different means is discussed.

  1. Beam current sensor

    Science.gov (United States)

    Kuchnir, Moyses; Mills, Frederick E.

    1987-01-01

    A current sensor for measuring the DC component of a beam of charged particles employs a superconducting pick-up loop probe, with twisted superconducting leads in combination with a Superconducting Quantum Interference Device (SQUID) detector. The pick-up probe is in the form of a single-turn loop, or a cylindrical toroid, through which the beam is directed and within which a first magnetic flux is excluded by the Meisner effect. The SQUID detector acts as a flux-to-voltage converter in providing a current to the pick-up loop so as to establish a second magnetic flux within the electrode which nulls out the first magnetic flux. A feedback voltage within the SQUID detector represents the beam current of the particles which transit the pick-up loop. Meisner effect currents prevent changes in the magnetic field within the toroidal pick-up loop and produce a current signal independent of the beam's cross-section and its position within the toroid, while the combination of superconducting elements provides current measurement sensitivites in the nano-ampere range.

  2. Beam profile monitor

    International Nuclear Information System (INIS)

    Krausse, G.J.; Gram, P.A.M.

    1978-05-01

    A system used to monitor secondary beam profiles at the LAMPF Linac for channel tune-up and diagnostics is described. The multiwire proportional chamber design is discussed, and descriptions and drawings of the gate card, the amplifier/multiplexer card, the output amplifier card, and the overall system are given

  3. Beam dynamics group summary

    Science.gov (United States)

    Peggs, S.

    This paper summarizes the activities of the beam dynamics working group of the LHC Collective Effects Workshop that was held in Montreux in 1994. It reviews the presentations that were made to the group, the discussions that ensued, and the consensuses that evolved.

  4. Dual beam vidicon digitizer

    International Nuclear Information System (INIS)

    Evans, T.L.

    1976-01-01

    A vidicon waveform digitizer which can simultaneously digitize two independent signals has been developed. Either transient or repetitive waveforms can be digitized with this system. A dual beam oscilloscope is used as the signal input device. The light from the oscilloscope traces is optically coupled to a television camera, where the signals are temporarily stored prior to digitizing

  5. Electron beam processing system

    International Nuclear Information System (INIS)

    Kashiwagi, Masayuki

    2004-01-01

    Electron beam Processing Systems (EPS) are used as useful and powerful tools in many industrial application fields such as the production of cross-linked wire, rubber tire, heat shrinkable film and tubing, curing, degradation of polymers, sterilization and environmental application. In this paper, the feature and application fields, the selection of machine ratings and safety measures of EPS will be described. (author)

  6. Ion beam studies

    International Nuclear Information System (INIS)

    Freeman, J.H.; Chivers, D.J.; Gard, G.A.; Temple, W.

    1977-04-01

    A description of techniques for the production of intense beams of heavy ions is given. A table of recommended operational procedures for most elements is included. The ionisation of boron is considered in some detail because of its particular importance as a dopant for ion implantation. (author)

  7. Beam in on curing

    International Nuclear Information System (INIS)

    Holl, Dr.

    1981-01-01

    Electron beam curing of paints and allied materials is discussed. Examples of applications are: silicone papers; painting of metal; bonding of flake adhesives; bonding of grinding media (binders); paints for external uses; painting shaped parts; bi-reactive painting systems. An example is given of the calculation of the cost of irradiation. (U.K.)

  8. Stochastic nonlinear beam equations

    Czech Academy of Sciences Publication Activity Database

    Brzezniak, Z.; Maslowski, Bohdan; Seidler, Jan

    2005-01-01

    Roč. 132, č. 1 (2005), s. 119-149 ISSN 0178-8051 R&D Projects: GA ČR(CZ) GA201/01/1197 Institutional research plan: CEZ:AV0Z10190503 Keywords : stochastic beam equation * stability Subject RIV: BA - General Mathematics Impact factor: 0.896, year: 2005

  9. LHC Report: Beam on

    CERN Multimedia

    Rossano Giachino for the LHC Team

    2012-01-01

    The powering tests described in the last edition of the Bulletin were successfully finished at the end of the first week of March opening the way for 4 TeV operations this year. The beam was back in the machine on Wednesday 14 March. The first collisions at 4 TeV are scheduled for the first week of April.   The first beam of 2012 is dumped after making a few rounds in the LHC. The magnet powering tests were followed by the machine checkout phase. Here the operations team in collaboration with the equipment groups performs a sequence of tests to ensure the readiness of the LHC for beam. The tests include driving all the LHC systems – beam dump, injection, collimation, RF, power converters, magnet circuits, vacuum, interlocks, controls, timing and synchronization – through the operational cycle. The “checkout phase” is really a massive de-bugging exercise, which is performed with the objective of ensuring the proper functioning of the whole machine and t...

  10. Continuous Reinforced Concrete Beams

    DEFF Research Database (Denmark)

    Hoang, Cao Linh; Nielsen, Mogens Peter

    1996-01-01

    This report deals with stress and stiffness estimates of continuous reinforced concrete beams with different stiffnesses for negative and positive moments e.g. corresponding to different reinforcement areas in top and bottom. Such conditions are often met in practice.The moment distribution...

  11. Recycled Paper Beam Sculpture

    Science.gov (United States)

    Keller, Kristin; Tabacchi, Jo

    2011-01-01

    As art department budgets across the country continue to shrink, art teachers are increasingly on the lookout for inexpensive materials that can be used to teach a range of concepts. In this article, the authors describe a newspaper beam tower project inspired by the book, "The Wonderful Towers of Watts" by Patricia Zelver. There are many more…

  12. Charged particle beams

    CERN Document Server

    Humphries, Stanley

    2013-01-01

    Detailed enough for a text and sufficiently comprehensive for a reference, this volume addresses topics vital to understanding high-power accelerators and high-brightness-charged particle beams. Subjects include stochastic cooling, high-brightness injectors, and the free electron laser. Humphries provides students with the critical skills necessary for the problem-solving insights unique to collective physics problems. 1990 edition.

  13. Nonlinear beam mechanics

    NARCIS (Netherlands)

    Westra, H.J.R.

    2012-01-01

    In this Thesis, nonlinear dynamics and nonlinear interactions are studied from a micromechanical point of view. Single and doubly clamped beams are used as model systems where nonlinearity plays an important role. The nonlinearity also gives rise to rich dynamic behavior with phenomena like

  14. Noninterceptive transverse beam diagnostics

    International Nuclear Information System (INIS)

    Chamberlin, D.D.; Minerbo, G.N.; Teel, L.E. Jr.; Gilpatrick, J.D.

    1981-01-01

    The transverse emittance properties of a high-current linear accelerator may be measured by using TV cameras sensitive to the visible radiation emitted following beam interactions with residual gas. This paper describes the TV system being used to measure emittances for the Fusion Materials Irradiation Test (FMIT) project

  15. Convergent beam neutron crystallography

    Science.gov (United States)

    Gibson, Walter M.; Schultz, Arthur J.; Richardson, James W.; Carpenter, John M.; Mildner, David F. R.; Chen-Mayer, Heather H.; Miller, M. E.; Maxey, E.; Prask, Henry J.; Gnaeupel-Herold, Thomas H.; Youngman, Russell

    2004-01-01

    Applications of neutron diffraction for small samples (small fiducial areas are limited by the available neutron flux density. Recent demonstrations of convergent beam electron and x-ray diffraction and focusing of cold (λ>1 Å) neutrons suggest the possibility to use convergent beam neutron diffraction for small sample crystallography. We have carried out a systematic study of diffraction of both monoenergetic and broad bandwidth neutrons at the NIST Research Reactor and at the Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory. Combining convergent beams with time-of-flight Laue diffraction is particularly attractive for high efficiency small sample diffraction studies. We have studied single crystal and powder diffraction of neutrons with convergence angles as large as 15° and have observed diffracted peak intensity gains greater than 20. The convergent beam method (CBM) shows promise for crystallography on small samples of small to medium size molecules (potentially even for proteins), ultra-high pressure samples, and for mapping of strain and texture distributions in larger samples.

  16. Beam Position Monitor Engineering

    International Nuclear Information System (INIS)

    Smith, Stephen R.

    1996-07-01

    The design of beam position monitors often involves challenging system design choices. Position transducers must be robust, accurate, and generate adequate position signal without unduly disturbing the beam. Electronics must be reliable and affordable, usually while meeting tough requirements on precision. accuracy, and dynamic range. These requirements may be difficult to achieve simultaneously, leading the designer into interesting opportunities for optimization or compromise. Some useful techniques and tools are shown. Both finite element analysis and analytic techniques will be used to investigate quasi-static aspects of electromagnetic fields such as the impedance of and the coupling of beam to striplines or buttons. Finite-element tools will be used to understand dynamic aspects of the electromagnetic fields of beams, such as wake-fields and transmission-line and cavity effects in vacuum-to-air feed through. Mathematical modeling of electrical signals through a processing chain will be demonstrated, in particular to illuminate areas where neither a pure time-domain nor a pure frequency-domain analysis is obviously advantageous. Emphasis will be on calculational techniques, in particular on using both time-domain and frequency domain approaches to the applicable parts of interesting problems

  17. Beam transport elements

    CERN Multimedia

    CERN PhotoLab

    1965-01-01

    Two of the beam transport elements for the slow ejection system. On the left, a quadrupole 1.2 m long with a 5 cm aperture, capable of producing a gradient of 5000 gauss. On the right, a 1 m bending magnet with a 4 cm gap; its field is 20 000 gauss.

  18. Beam experiment at TARN

    International Nuclear Information System (INIS)

    Noda, A.; Chida, K.; Hattori, T.

    1984-01-01

    TARN is a storage ring of low energy ions (T sub(N) -- 10 MeV/u) constructed in 1979 to verify the feasibility of intensity multiplication proposed at NUMATRON project. The mean radius and maximum magnetic rigidity of the ring are 5.06 m and 11.8 kG.m, respectively. Magnet system based on a strong focusing FODO lattice is composed of 8 dipole and 16 quadrupole magnets. Additional 12 sextupole magnets are also installed for chromaticity control. Intensity increase by the multi-turn injection is 20 times with the dilution factor of 2.0 in horizontal transverse phase space. Injected beams are RF captured with the frequency around 8 MHz and moved inner side of the ring by RF deceleration as large as -- 5 % in Δp/p. Beam intensity increases linearly up to around 20 stackings with the capture efficiency of 80 % and 30 Hz repetition rate. Dilution factor of the longitudinal phase space is measured at 1.8. Thus about 300 times total intensity increase has been attained. The e-folding beam life time of 7 MeV proton is measured at 400 s for the vacuum pressure of 1 x 10 -10 Torr. Stochastic momentum cooling experiment of 7 MeV proton has been performed. A feed-back system based on the 'Notch-Filter' method has been adopted for its simplicity and characteristics suitable for lower beam intensity. Cooling time for the 7 MeV proton beam with the intensity of 10 8 is estimated at 19 s for optimum cooling rate with the system gain of 105 dB, while the system gain as large as 111 dB has been achieved without self-oscillation of the electronics system. From the beam experiment, the cooling time of 10 8 proton beam with fractional momentum spread of 1.4 x 10 -2 is measured at --20 sec with the system gain of 97 db. (author)

  19. BATMAN beam properties characterization by the beam emission spectroscopy diagnostic

    Science.gov (United States)

    Bonomo, F.; Ruf, B.; Barbisan, M.; Cristofaro, S.; Schiesko, L.; Fantz, U.; Franzen, P.; Pasqualotto, R.; Riedl, R.; Serianni, G.; Wünderlich, D.

    2015-04-01

    The ITER neutral beam heating systems are based on the production and acceleration of negative ions (H/D) up to 1 MV. The requirements for the beam properties are strict: a low core beam divergence (BATMAN (BAvarian Test MAchine for Negative ions) allows for deepening the knowledge of the determination of the beam properties. One of the diagnostics routinely used to this purpose is the Beam Emission Spectroscopy (BES): the Hα light emitted in the beam is detected and the corresponding spectra are evaluated to estimate the beam divergence and the stripping losses. The BES number of lines of sight in BATMAN has been recently increased: five horizontal lines of sight providing a vertical profile of the beam permit to characterize the negative ion beam properties in relation to the source parameters. Different methods of Hα spectra analysis are here taken into account and compared for the estimation of the beam divergence and the amount of stripping. In particular, to thoroughly study the effect of the space charge compensation on the beam divergence, an additional hydrogen injection line has been added in the tank, which allows for setting different background pressure values (one order of magnitude, from about 0.04 Pa up to the source pressure) in the beam drift region.

  20. A beam source model for scanned proton beams.

    Science.gov (United States)

    Kimstrand, Peter; Traneus, Erik; Ahnesjö, Anders; Grusell, Erik; Glimelius, Bengt; Tilly, Nina

    2007-06-07

    A beam source model, i.e. a model for the initial phase space of the beam, for scanned proton beams has been developed. The beam source model is based on parameterized particle sources with characteristics found by fitting towards measured data per individual beam line. A specific aim for this beam source model is to make it applicable to the majority of the various proton beam systems currently available or under development, with the overall purpose to drive dose calculations in proton beam treatment planning. The proton beam phase space is characterized by an energy spectrum, radial and angular distributions and deflections for the non-modulated elementary pencil beam. The beam propagation through the scanning magnets is modelled by applying experimentally determined focal points for each scanning dimension. The radial and angular distribution parameters are deduced from measured two-dimensional fluence distributions of the elementary beam in air. The energy spectrum is extracted from a depth dose distribution for a fixed broad beam scan pattern measured in water. The impact of a multi-slab range shifter for energy modulation is calculated with an own Monte Carlo code taking multiple scattering, energy loss and straggling, non-elastic and elastic nuclear interactions in the slab assembly into account. Measurements for characterization and verification have been performed with the scanning proton beam system at The Svedberg Laboratory in Uppsala. Both in-air fluence patterns and dose points located in a water phantom were used. For verification, dose-in-water was calculated with the Monte Carlo code GEANT 3.21 instead of using a clinical dose engine with approximations of its own. For a set of four individual pencil beams, both with the full energy and range shifted, 96.5% (99.8%) of the tested dose points satisfied the 1%/1 mm (2%/2 mm) gamma criterion.

  1. Computer simulation of electron beams

    Energy Technology Data Exchange (ETDEWEB)

    Sabchevski, S.P.; Mladenov, G.M. (Bylgarska Akademiya na Naukite, Sofia (Bulgaria). Inst. po Elektronika)

    1994-04-14

    Self-fields and forces as well as the local degree of space-charge neutralization in overcompensated electron beams are considered. The radial variation of the local degree of space-charge neutralization is analysed. A novel model which describes the equilibrium potential distribution in overcompensated beams is proposed and a method for computer simulation of the beam propagation is described. Results from numerical experiments which illustrate the propagation of finite emittance overneutralized beams are presented. (Author).

  2. Polarized atomic beams for targets

    International Nuclear Information System (INIS)

    Grueebler, W.

    1984-01-01

    The basic principle of the production of polarized atomic hydrogen and deuterium beams are reviewed. The status of the present available polarization, density and intensity are presented. The improvement of atomic beam density by cooling the hydrogen atoms to low velocity is discussed. The possible use of polarized atomic beams as targets in storage rings is shown. It is proposed that polarized atomic beams can be used to produce polarized gas targets with high polarization and greatly improved density

  3. Study of beam-beam long range compensation with octupoles

    CERN Document Server

    AUTHOR|(CDS)2068329; Pieloni, Tatiana; Buffat, Xavier; Tambasco, Claudia

    2017-01-01

    Long range beam-beam effects are responsible for particle losses and define fundamental operational parameters of colliders (i.e. crossing angles, intensities, emittances, ${\\beta}$${^∗}$). In this study we propose octuple magnets as a possible scheme to efficiently compensate long-range beam-beam interactions with a global correction scheme. The impact and improvements on the dynamic aperture of colliding beams together with estimates of the luminosity potentials are dis- cussed for the HL-LHC upgrade and extrapolations made for the FCC project.

  4. Beam Dynamics Simulation for the CTF3 Drive Beam Accelerator

    CERN Document Server

    Schulte, Daniel

    2000-01-01

    A new CLIC Test Facility (CTF3) at CERN will serve to study the drive beam generation for the Compact Linear Collider (CLIC). CTF3 has to accelerate a 3.5 A electron beam in almost fully-loaded structures. The pulse contains more than 2000 bunches, one in every second RF bucket, and has a length of more than one microsecond. Different options for the lattice of the drive-beam accelerator are presented, based on FODO-cells and triplets as well as solenoids. The transverse stability is simulated, including the effects of beam jitter, alignment and beam-based correction.

  5. Single Gradientless Light Beam Drags Particles as Tractor Beams

    DEFF Research Database (Denmark)

    Novitsky, Andrey; Qiu, Cheng-Wei; Wang, Haifeng

    2011-01-01

    is the strong nonparaxiality of the light beam, which contributes to the pulling force owing to momentum conservation. The nonparaxiality of the Bessel beam can be manipulated to possess a dragging force along both the radial longitudinal directions, i.e., a "tractor beam" with stable trajectories is achieved......Usually a light beam pushes a particle when the photons act upon it. We investigate the optical forces by nonparaxial gradientless beams and find that the forces can drag suitable particles all the way towards the light source. The major criterion of realizing the backward dragging force...

  6. Spatial superpositions of Gaussian beams

    CSIR Research Space (South Africa)

    Naidoo, Darryl

    2014-02-01

    Full Text Available ., “Bottle beam from a bare laser for single-beam trapping,” Appl. Opt. 43, 6001–6006 (2004). [11] Ahluwalia B. P. S., Yuan X. C. and Tao S. H., “Generation of self-imaged optical bottle beams,” Opt. Commun. 238, 177–184 (2004). [12] Isenhower L...

  7. Nuclear physics with radioactive beams

    International Nuclear Information System (INIS)

    Bimbot, R.

    1994-01-01

    Radioactive beam production through two different mechanisms: acceleration of radioactive nuclei, and production of secondary beams from projectile fragmentation is overviewed. Some topics of the applications of radioactive beams in nuclear physics, such as identification and study of exotic nuclei, neutron halos, nuclear astrophysics and medical applications are discussed. (K.A.). 24 refs., 8 figs

  8. Depressed collector for electron beams

    Science.gov (United States)

    Ives, R. Lawrence (Inventor)

    2005-01-01

    A depressed collector for recovery of spent beam energy from electromagnetic sources emitting sheet or large aspect ration annular electron beams operating aver a broad range of beam voltages and currents. The collector incorporates a trap for capturing and preventing the return of reflected and secondary electrons.

  9. Flat profile laser beam shaper

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Todd R.

    2017-09-12

    A system for shaping a beam comprises an emitter for emitting coherent electromagnetic radiation. Birefringent displacers are configured between the emitter and a target wherein the at least two birefringent displacers split the coherent electromagnetic radiation into a plurality of coherent parallel beams of electromagnetic radiation thereby producing a shaped wave front of the coherent parallel beams of electromagnetic radiation.

  10. Definition of Beam Diameter for Electron Beam Welding

    Energy Technology Data Exchange (ETDEWEB)

    Burgardt, Paul [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Pierce, Stanley W. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dvornak, Matthew John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-03-11

    It is useful to characterize the dimensions of the electron beam during process development for electron beam welding applications. Analysis of the behavior of electron beam welds is simplest when a single number can be assigned to the beam properties that describes the size of the beam spot; this value we generically call the “beam diameter”. This approach has worked well for most applications and electron beam welding machines with the weld dimensions (width and depth) correlating well with the beam diameter. However, in recent weld development for a refractory alloy, Ta-10W, welded with a low voltage electron beam machine (LVEB), it was found that the weld dimensions (weld penetration and weld width) did not correlate well with the beam diameter and especially with the experimentally determined sharp focus point. These data suggest that the presently used definition of beam diameter may not be optimal for all applications. The possible reasons for this discrepancy and a suggested possible alternative diameter definition is the subject of this paper.

  11. Closed orbit distortion and the beam-beam interaction

    Energy Technology Data Exchange (ETDEWEB)

    Furman, M.; Chin, Y.H.; Eden, J. [Lawrence Berkeley Lab., CA (United States); Kozanecki, W. [CEA Centre d`Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France)]|[Stanford Linear Accelerator Center, Menlo Park, CA (United States); Tennyson, J.; Ziemann, V. [Stanford Linear Accelerator Center, Menlo Park, CA (United States)

    1992-06-01

    We study the applicability of beam-beam deflection techniques as a tuning tool for the SLAC/LBL/LLNL B factory, PEP-II. Assuming that the closed orbits of the two beams are separated vertically at the interaction point by a local orbit bump that is nominally closed, we calculate the residual beam orbit distortions due to the beam-beam interaction. Difference orbit measurements, performed at points conveniently distant from the IP, provide distinct coordinate- or frequency-space signatures that can be used to maintain the beams in collision and perform detailed optical diagnostics at the IP. A proposal to test this method experimentally at the TRISTAN ring is briefly discussed.

  12. Coherent Beam-Beam Effects in the LHC

    CERN Document Server

    Alexahin, Yu I; Herr, Werner; Zorzano-Mier, M P

    2001-01-01

    In the Large Hadron Collider (LHC) two proton beams of similar intensities collide in several interaction points. It is well known that the head-on collision of two beams of equal strength can excite coherent modes whose frequencies are separated from the incoherent spectrum of oscillations of individual particles. This can lead to the loss of Landau damping and possibly to unstable motion. The beam-beam effect in the LHC is further complicated by a large number of bunches (2808 per beam), a finite crossing angle and gaps in the bunch train. The coherent beam-beam effects under various conditions and operational scenarios are studied analytically and with multiparticle simulations. We give an overview of the main results and present proposals to overcome these difficulties together with possible side effects.

  13. Heavy ion beam probing

    Energy Technology Data Exchange (ETDEWEB)

    Hickok, R L

    1980-07-01

    This report consists of the notes distributed to the participants at the IEEE Mini-Course on Modern Plasma Diagnostics that was held in Madison, Wisconsin in May 1980. It presents an overview of Heavy Ion Beam Probing that briefly describes the principles and discuss the types of measurements that can be made. The problems associated with implementing beam probes are noted, possible variations are described, estimated costs of present day systems, and the scaling requirements for large plasma devices are presented. The final chapter illustrates typical results that have been obtained on a variety of plasma devices. No detailed calculations are included in the report, but a list of references that will provide more detailed information is included.

  14. Heavy ion beam probing

    International Nuclear Information System (INIS)

    Hickok, R.L.

    1980-07-01

    This report consists of the notes distributed to the participants at the IEEE Mini-Course on Modern Plasma Diagnostics that was held in Madison, Wisconsin in May 1980. It presents an overview of Heavy Ion Beam Probing that briefly describes the principles and discuss the types of measurements that can be made. The problems associated with implementing beam probes are noted, possible variations are described, estimated costs of present day systems, and the scaling requirements for large plasma devices are presented. The final chapter illustrates typical results that have been obtained on a variety of plasma devices. No detailed calculations are included in the report, but a list of references that will provide more detailed information is included

  15. A simple beam analyser

    International Nuclear Information System (INIS)

    Lemarchand, G.

    1977-01-01

    (ee'p) experiments allow to measure the missing energy distribution as well as the momentum distribution of the extracted proton in the nucleus versus the missing energy. Such experiments are presently conducted on SACLAY's A.L.S. 300 Linac. Electrons and protons are respectively analysed by two spectrometers and detected in their focal planes. Counting rates are usually low and include time coincidences and accidentals. Signal-to-noise ratio is dependent on the physics of the experiment and the resolution of the coincidence, therefore it is mandatory to get a beam current distribution as flat as possible. Using new technologies has allowed to monitor in real time the behavior of the beam pulse and determine when the duty cycle can be considered as being good with respect to a numerical basis

  16. Focused ion beam technology

    International Nuclear Information System (INIS)

    Gamo, K.

    1993-01-01

    Focussed ion beam (FIB) technology has the advantage of being a maskless process compatible with UHV processing. This makes it attractive for use in in situ processing and has been applied to the fabrication of various mesoscopic structures. The present paper reviews these results whilst putting emphasis on in situ processing by a combined FIB and molecular beam epitaxy system. The typical performance of present FIB systems is also presented. In order to utilize the potential advantages of FIB processing, reduction of damage and improvement of throughput are important, and much effort has been devoted to developing processing techniques which require a reduced dose. The importance of low-energy FIB is discussed. (author)

  17. Electron beam fusion targets

    International Nuclear Information System (INIS)

    Clauser, M.J.; Sweeney, M.A.

    1975-01-01

    R The behavior of the DT filled gold shells when irradiated by a variety of pulse shapes was studied. In these pulses the power (and beam current) was varied, but the voltage was kept constant at 1 MeV. In general the performance of the target, for a given peak power, was not significantly affected by the pulse shape. Pulses with rise times of up to half the implosion time do not significantly degrade the target performance. The use of the ''optimal pulse'' of laser fusion with a fixed peak power does not appear to improve the performance of these targets. The main function of the ''optimal pulse'' is to produce a large rho r of the target during the thermonuclear burn. In e-beam targets a total rho r of 5--10 g/cm 2 can be obtained without pulse shaping; the problem here is one of achieving high enough temperatures to ignite the DT. (U.S.)

  18. Electron beams in radiation therapy

    International Nuclear Information System (INIS)

    Bruinvis, I.A.D.

    1987-01-01

    Clinical electron beams in interaction with beam flattening and collimating devices are studied, in order to obtain the means for adequate electron therapy. A treatment planning method for arbitrary field shapes is developed that takes the properties of the collimated electron beams into account. An electron multiple-scattering model is extended to incorporate a model for the loss of electrons with depth, in order to improve electron beam dose planning. A study of ionisation measurements in two different phantom materials yields correction factors for electron beam dosimetry. (Auth.)

  19. Proton beam therapy facility

    International Nuclear Information System (INIS)

    1984-01-01

    It is proposed to build a regional outpatient medical clinic at the Fermi National Accelerator Laboratory (Fermilab), Batavia, Illinois, to exploit the unique therapeutic characteristics of high energy proton beams. The Fermilab location for a proton therapy facility (PTF) is being chosen for reasons ranging from lower total construction and operating costs and the availability of sophisticated technical support to a location with good access to patients from the Chicago area and from the entire nation. 9 refs., 4 figs., 26 tabs

  20. Beam-Material Interaction

    CERN Document Server

    Mokhov, N.V.

    2016-01-01

    Th is paper is motivated by the growing importance of better understanding of the phenomena and consequences of high- intensity energetic particle beam interactions with accelerator, generic target , and detector components. It reviews the principal physical processes of fast-particle interactions with matter, effects in materials under irradiation, materials response, related to component lifetime and performance, simulation techniques, and methods of mitigating the impact of radiation on the components and envir onment in challenging current and future application

  1. Relativistic electron beam device

    Science.gov (United States)

    Freeman, J.R.; Poukey, J.W.; Shope, S.L.; Yonas, G.

    1975-07-01

    A design is given for an electron beam device for irradiating spherical hydrogen isotope bearing targets. The accelerator, which includes hollow cathodes facing each other, injects an anode plasma between the cathodes and produces an approximately 10 nanosecond, megajoule pulse between the anode plasma and the cathodes. Targets may be repetitively positioned within the plasma between the cathodes, and accelerator diode arrangement permits materials to survive operation in a fusion power source. (auth)

  2. Beam-Material Interaction

    Energy Technology Data Exchange (ETDEWEB)

    Mokhov, N. V. [Fermilab; Cerutti, F. [CERN

    2016-01-01

    Th is paper is motivated by the growing importance of better understanding of the phenomena and consequences of high-intensity energetic particle beam interactions with accelerator, generic target, and detector components. It reviews the principal physical processes of fast-particle interactions with matter, effects in materials under irradiation, materials response, related to component lifetime and performance, simulation techniques, and methods of mitigating the impact of radiation on the components and environment in challenging current and future applications.

  3. Stationary nonlinear Airy beams

    International Nuclear Information System (INIS)

    Lotti, A.; Faccio, D.; Couairon, A.; Papazoglou, D. G.; Panagiotopoulos, P.; Tzortzakis, S.; Abdollahpour, D.

    2011-01-01

    We demonstrate the existence of an additional class of stationary accelerating Airy wave forms that exist in the presence of third-order (Kerr) nonlinearity and nonlinear losses. Numerical simulations and experiments, in agreement with the analytical model, highlight how these stationary solutions sustain the nonlinear evolution of Airy beams. The generic nature of the Airy solution allows extension of these results to other settings, and a variety of applications are suggested.

  4. Lessons in beam diagnostics

    International Nuclear Information System (INIS)

    Jones, O.R.

    2012-01-01

    This paper will concentrate on the studies carried out on LHC beam instrumentation systems during the 2011 run, the improvements made and the outlook for 2012. It will include an update on the issues resolved since 2010, such as the performance of the BCT systems, and discuss advances in the bunch by bunch measurement capability of many systems. The paper will also highlight what can be hoped for in terms of performance for 2012 and the issues which remain to be solved. (author)

  5. Beam in on curing

    International Nuclear Information System (INIS)

    Holl, Dr.

    1981-01-01

    This third part of an article on the electron beam curing of paints covers the following aspects: inertising equipment; working without inert gas; increase in temperature when irradiating; irradiating plants; laboratory plants; plant operating from coil to coil; plant for shaped parts; possible applications; decorative films, paper, PVC; packaging material; metallisation of paper films; film bonding; strengthening of flock; coating; pressure sensitive adhesives. (U.K.)

  6. Beam screen issues

    CERN Document Server

    Métral, E

    2011-01-01

    In the High Energy LHC (HE-LHC), a beam energy of about 16.5 TeV is currently contemplated. The beam screen issues linked to the use of 20 T dipole magnets instead of 8.33 T are discussed, with a particular emphasis on two mechanisms, the magneto-resistance and the anomalous skin effect, assuming the nominal machine and beam parameters. The magneto-resistance effect always leads to an increase of the material resistivity (as the mean free path in the presence of a transverse magnetic field becomes smaller). As concerns the anomalous skin effect, the anomalous increase of surface resistance of metals at low temperatures and high frequencies is attributed to the long mean free path of the conduction electrons: when the skin depth becomes much smaller than the mean free path, only a fraction of the conduction electrons moving almost parallel to the metal surface is effective in carrying the current and the classical theory breaks down.

  7. The beam transport system

    International Nuclear Information System (INIS)

    1986-01-01

    The first proton beams have been transported along the transfer beamline and the diagnostic components have thus been used and tested under real operating conditions. The various electronic systems have been linked to the control system and the equipment can now be operated from the control console. The performance of the diagnostic system for the transfer beamline is satisfactory. The beam diagnostic components for the high-energy beamlines up to the isotope production and neutron therapy vaults and the first experimental target rooms have been installed. The high-energy slits have been delivered. The scanner and harp electronics have been installed and linked to their respective components in the beamlines. The pneumatic acuator control electronics has been manufactured, installed and is operational; provision has been made for special control features of the equipment in the therapy beamline. The high-voltage bias supply for the Faraday cups has been implemented. The installation of the beam current measurement system is nearing completion although part of it is already operational. A coaxial relay multiplexer for the capacitive phase probe signals has been manufactured and installed. The diagnostic equipment for the beamlines to isotope production and neutron therapy is thus ready for operation. 4 figs

  8. Hyperon Beam Experiment

    CERN Multimedia

    2002-01-01

    The experiment WA89 uses the upgraded Omega facility together with a hyperon beam installed at the end of the H1 beamline. The beam can deliver 2~10$ ^{5} \\% Sigma ^- $ per machine burst at 330 GeV/c with a background of 5 10$ ^{5} \\% \\pi ^- $. \\\\ \\\\ The goals of the experiment are: observation of charmed particles, mainly the charmed-strange baryons and measurements of their production in the kinematical range x$ _{F} $~$>$~0.2, and their decay properties, a search for exotic states such as U(3100) observed in the previous CERN hyperon beam experiment WA62, measurements of hyperon polarization and production properties. \\\\ \\\\ A vertex detector consisting of 24 silicon microstrip planes with 25~$\\mu$m pitch and 6~planes with 50~$\\mu$m pitch provides track measurements of sufficient accuracy to identify the decays of short living charmed particles and measure their lifetimes. A RICH detector provides good $\\pi$/K separation for momenta up to 100~GeV/c and $\\pi$/p separation up to 150~GeV/c. Photons are detecte...

  9. Fixed target beams

    CERN Document Server

    Kain, V; Cettour-Cave, S; Cornelis, K; Fraser, M A; Gatignon, L; Goddard, B; Velotti, F

    2017-01-01

    The CERN SPS (Super Proton Synchrotron) serves asLHC injector and provides beam for the North Area fixedtarget experiments. At low energy, the vertical acceptancebecomes critical with high intensity large emittance fixed tar-get beams. Optimizing the vertical available aperture is a keyingredient to optimize transmission and reduce activationaround the ring. During the 2016 run a tool was developed toprovide an automated local aperture scan around the entirering.The flux of particles slow extracted with the1/3inte-ger resonance from the Super Proton Synchrotron at CERNshould ideally be constant over the length of the extractionplateau, for optimum use of the beam by the fixed target ex-periments in the North Area. The extracted intensity is con-trolled in feed-forward correction of the horizontal tune viathe main SPS quadrupoles. The Mains power supply noiseat 50 Hz and harmonics is also corrected in feed-forwardby small amplitude tune modulation at the respective fre-quencies with a dedicated additional quad...

  10. Particle beams and plasmas

    International Nuclear Information System (INIS)

    Hofmann, A.; Messerschmid, E.; Lawson, J.D.

    1976-01-01

    These lectures present a survey of some of the concepts of plasma physics and look at some situations familiar to particle-accelerator physicists from the point of view of a plasma physicist, with the intention of helping to link together the two fields. At the outset, basic plasma concepts are presented, including definitions of a plasma, characteristic parameters, magnetic pressure and confinement. This is followed by a brief discussion on plasma kinetic theory, non-equilibrium plasma, and the temperature of moving plasmas. Examples deal with beams in the CERN Intersecting Storage Rings as well as with non-steady beams in cyclic accelerators and microwave tubes. In the final chapters, time-varying systems are considered: waves in free space and the effect of cylinder bounds, wave motion in cold stationary plasmas, and waves in plasmas with well-defined streams. The treatment throughout is informal, with emphasis on the essential physical properties of continuous beams in accelerators and storage rings in relation to the corresponding problems in plasma physics and microwave tubes. (Author)

  11. Premature beam dumps in 2011

    CERN Document Server

    Albert, Markus

    2012-01-01

    The statistical analysis of all non-programmed beam dumps during the 2011 proton run is presented. The selection criteria of fills that got considered were that the beam intensity of each of the two beams exceeded at least 1e12 particles per beam in order to exclude all probe beam dumps and most of the MPS test dumps. A distribution of beam dump causes by system is shown, as well as the time it took to re-establish injection after a non-programmed dump for fills which made it into STABLE BEAMS. This was done in an attempt to evaluate the cost of those non-programmed dumps in terms of time.

  12. CLIC Drive Beam Phase Stabilisation

    CERN Document Server

    Gerbershagen, Alexander; Schulte, Daniel

    The thesis presents phase stability studies for the Compact Linear Collider (CLIC) and focuses in particular on CLIC Drive Beam longitudinal phase stabilisation. This topic constitutes one of the main feasibility challenges for CLIC construction and is an essential component of the current CLIC stabilisation campaign. The studies are divided into two large interrelated sections: the simulation studies for the CLIC Drive Beam stability, and measurements, data analysis and simulations of the CLIC Test Facility (CTF3) Drive Beam phase errors. A dedicated software tool has been developed for a step-by-step analysis of the error propagation through the CLIC Drive Beam. It uses realistic RF potential and beam loading amplitude functions for the Drive and Main Beam accelerating structures, complete models of the recombination scheme and compressor chicane as well as of further CLIC Drive Beam modules. The tool has been tested extensively and its functionality has been verified. The phase error propagation at CLIC h...

  13. Ion beam generation and focusing

    International Nuclear Information System (INIS)

    Miller, P.A.; Mendel, C.W.; Swain, D.W.; Goldstein, S.A.

    1975-01-01

    Calculations have shown that efficiently generated and focused ion beams could have significant advantages over electron beams in achieving ignition of inertially-confined thermonuclear fuel. Efficient ion beam generation implies use of a good ion source and suppression of net electron current. Net electron flow can be reduced by allowing electrons to reflex through a highly transparent anode or by use of transverse magnetic fields (either beam self-fields or externally applied fields). Geometric focusing can be achieved if the beam is generated by appropriately shaped electrodes. Experimental results are presented which demonstrate ion beam generation in both reflexing and pinched-flow diodes. Spherically shaped electrodes are used to concentrate a proton beam, and target response to proton deposition is studied

  14. Operational beams for the LHC

    CERN Document Server

    Papaphilippou, Y.; Rumolo, G.; Manglunki, D.

    2014-01-01

    The variety of beams, needed to set-up in the injectors as requested in the LHC, are reviewed, in terms of priority but also performance expectations and reach during 2015. This includes the single bunch beams for machine commissioning and measurements (probe, Indiv) but also the standard physics beams with 50 ns and 25 ns bunch spacing and their high brightness variants using the Bunch Compression Merging and Splitting (BCMS) scheme. The required parameters and target performance of special beams like the doublet for electron cloud enhancement and the more exotic 8b$\\oplus$4e beam, compatible with some post-scrubbing scenarios are also described. The progress and plans for the LHC ion production beams during 2014-2015 are detailed. Highlights on the current progress of the setting up of the various beams are finally presented with special emphasis on potential performance issues across the proton and ion injector chain.

  15. IMPACT simulation and the SNS linac beam

    International Nuclear Information System (INIS)

    Zhang, Y.; Qiang, J.

    2008-01-01

    Multi-particle tracking simulations for the SNS linac beam dynamics studies are performed with the IMPACT code. Beam measurement results are compared with the computer simulations, including beam longitudinal halo and beam losses in the superconducting linac, transverse beam Courant-Snyder parameters and the longitudinal beam emittance in the linac. In most cases, the simulations show good agreement with the measured results

  16. Energy transparency and symmetries in the beam-beam interaction

    Directory of Open Access Journals (Sweden)

    S. Krishnagopal

    2000-02-01

    Full Text Available We have modified the beam-beam simulation code CBI to handle asymmetric beams and used it to look at energy transparency and symmetries in the beam-beam interaction. We find that even a small violation of energy transparency, or of the symmetry between the two beams, changes the character of the collective (coherent motion; in particular, period-n oscillations are no longer seen. We speculate that the one-time observation of these oscillations at LEP, and the more ubiquitous observation of the flip-flop instability in colliders around the world, may be a consequence of breaking the symmetry between the electron and positron beams. We also apply this code to the asymmetric collider PEP-II, and find that for the nominal parameters of PEP-II, in particular, the nominal tune-shift parameter of ξ_{0}=0.03, there are no collective beam-beam issues. Collective quadrupole motion sets in only at ξ_{0}=0.06 and above, consistent with earlier observations for symmetric beams.

  17. Coherent Beam-Beam Oscillations at the LHC

    CERN Document Server

    Zorzano-Mier, M P

    1999-01-01

    The transverse coherent motion of the two colliding LHC beams is studied by multi-particle tracking, where the beam-beam force is calculated assuming a Gaussian beam distribution with variable barycentres and rms beam sizes. The simulation yields the coherent and incoherent oscillation frequencies, the emittance growth of either beam, and evidence for the existence or lack of Landau damping. The transverse beam sizes change with the fractional part of the tune as expected from the dynamic beta effect. For head-on collisions, we find that the pi-mode frequency lies outside of the continuum frequency spread if the ratio of the beam-beam parameters exceeds 0.6, in accordance with predictions [1]. For smaller ratios, the pi-mode is Landau damped. When long range interactions are also included, undamped coherent modes do still exist outside the continuum, both with and without alternating crossing planes at two interaction points. However, the simulation shows that separating the tunes of the two beams can restore...

  18. BATMAN beam properties characterization by the beam emission spectroscopy diagnostic

    Energy Technology Data Exchange (ETDEWEB)

    Bonomo, F., E-mail: federica.bonomo@igi.cnr.it [Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), Corso Stati Uniti 4, 35127 Padova (Italy); Istituto Gas Ionizzati - CNR, Corso Stati Uniti 4, 35127 Padova (Italy); Ruf, B.; Schiesko, L.; Fantz, U.; Franzen, P.; Riedl, R.; Wünderlich, D. [Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching (Germany); Barbisan, M.; Pasqualotto, R.; Serianni, G. [Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), Corso Stati Uniti 4, 35127 Padova (Italy); Cristofaro, S. [Universitá degli Studi di Padova, Via 8 Febbraio 2, 35122 Padova (Italy)

    2015-04-08

    The ITER neutral beam heating systems are based on the production and acceleration of negative ions (H/D) up to 1 MV. The requirements for the beam properties are strict: a low core beam divergence (< 0.4 °) together with a low source pressure (≤ 0.3 Pa) would permit to reduce the ion losses along the beamline, keeping the stripping particle losses below 30%. However, the attainment of such beam properties is not straightforward. At IPP, the negative ion source testbed BATMAN (BAvarian Test MAchine for Negative ions) allows for deepening the knowledge of the determination of the beam properties. One of the diagnostics routinely used to this purpose is the Beam Emission Spectroscopy (BES): the H{sub α} light emitted in the beam is detected and the corresponding spectra are evaluated to estimate the beam divergence and the stripping losses. The BES number of lines of sight in BATMAN has been recently increased: five horizontal lines of sight providing a vertical profile of the beam permit to characterize the negative ion beam properties in relation to the source parameters. Different methods of H{sub α} spectra analysis are here taken into account and compared for the estimation of the beam divergence and the amount of stripping. In particular, to thoroughly study the effect of the space charge compensation on the beam divergence, an additional hydrogen injection line has been added in the tank, which allows for setting different background pressure values (one order of magnitude, from about 0.04 Pa up to the source pressure) in the beam drift region.

  19. Detection of coherent beam-beam modes with digitized beam position monitor signals

    CERN Document Server

    Stancari, G.; White, S.M.

    2014-01-01

    A system for bunch-by-bunch detection of transverse proton and antiproton coherent oscillations in the Fermilab Tevatron collider is described. It is based on the signal from a single beam-position monitor located in a region of the ring with large amplitude functions. The signal is digitized over a large number of turns and Fourier-analyzed offline with a dedicated algorithm. To enhance the signal, band-limited noise is applied to the beam for about 1 s. This excitation does not adversely affect the circulating beams even at high luminosities. The device has a response time of a few seconds, a frequency resolution of $1.6\\times 10^{-5}$ in fractional tune, and it is sensitive to oscillation amplitudes of 60 nm. It complements Schottky detectors as a diagnostic tool for tunes, tune spreads, and beam-beam effects. Measurements of coherent mode spectra are presented and compared with models of beam-beam oscillations.

  20. Beam line design using G4BeamLine

    CERN Document Server

    Dogan, Arda

    2014-01-01

    In Turkey in Ankara TAEK SANAEM Proton Accelerator Facility (PAF), there is a cyclotron which produces a focused intense 30 MeV proton beam and sends this beam to four different arms, three of which uses this beam to produce pharmaceutical medicine. The remaining one is spared for R&D purposes and the idea was to use these protons coming out from the fourth arm to use space radiation tests, which cannot be done in Turkey at the moment. However, according to SCC 25100 standards which is for 30 MeV protons, the beam coming out of cyclotron is too intense and focused to use for space radiation tests. Therefore, the main aim of my project is to design a beam line which will defocus the beam and reduce the flux so that the space radiation tests can be done according to the standards of SCC 25100.

  1. Beam tuning and stabilization using beam phase measurements at GANIL

    International Nuclear Information System (INIS)

    Chabert, A.; Loyer, F.; Sauret, J.

    1984-06-01

    Owing to the great sensitivity of the beam phase to the various parameters, on line beam phase measurements proved to be a very efficient way of tuning and stabilizing the beam of the multi-accelerator complex. We recall the system which allows to obtain the different kinds of accurate measurements we need and describe the main applications: - tuning process (buncher and SSC's RF phase determination, setting of the required radial beam phase law in the SSC's); - stabilization of the beam by loops, the basic principle of which being to keep constant the beam central phase all along the machine by adjusting RF voltages or magnetic fields. Feedback loops are described and comparative results with and without feedback are given

  2. 6D beam-beam interaction step-by-step

    CERN Document Server

    Iadarola, Giovanni; Papaphilippou, Yannis; CERN. Geneva. ATS Department

    2017-01-01

    This document describes in detail the numerical method used in different simulation codes for the simulation of beam-beam interactions using the “Synchro Beam Mapping” approach, in order to correctly model the coupling introduced by beam-beam between the longitudinal and the transverse plane. The goal is to provide in a compact, complete and self-consistent manner the set of equations needed for the implementation in a numerical code. The effect of a “crossing angle” in an arbitrary “crossing plane” with respect to the assigned reference frame is taken into account with a suitable coordinate transformation. The employed description of the strong beam allows correctly accounting for the hour-glass effect as well as for linear coupling at the interaction point.

  3. H- beam neutralization measurements in a solenoidal beam transport system

    International Nuclear Information System (INIS)

    Sherman, J.; Pitcher, E.; Stevens, R.; Allison, P.

    1992-01-01

    H minus beam space-charge neutralization is measured for 65-mA, 35-keV beams extracted from a circular-aperture Penning surface-plasma source, the small-angle source. The H minus beam is transported to a RFQ matchpoint by a two-solenoid magnet system. Beam noise is typically ±4%. A four-grid analyzer is located in a magnetic-field-free region between the two solenoid magnets. H minus potentials are deduced from kinetic energy measurements of particles (electrons and positive ions) ejected radially from the beam channel by using a griddled energy analyzer. Background neutral gas density is increased by the introduction of additional Xe and Ar gases, enabling the H minus beam to become overneutralized

  4. LHC Beam Instrumentation: Beam Profile Measurements (2/3)

    CERN Multimedia

    CERN. Geneva

    2014-01-01

    The LHC is equipped with a full suite of sophisticated beam instrumentation which has been essential for rapid commissioning, the safe increase in total stored beam power and the understanding of machine optics and accelerator physics phenomena. These lectures will introduce these systems and comment on their contributions to the various stages of beam operation. They will include details on: the beam position system and its use for real-time global orbit feedback; the beam loss system and its role in machine protection; total and bunch by bunch intensity measurements; tune measurement and feedback; diagnostics for transverse beam size measurements, abort gap monitoring and longitudinal density measurements. Issues and problems encountered along the way will also be discussed together with the prospect for future upgrades.

  5. BEAM HALO FORMATION IN HIGH-INTENSITY BEAMS.

    Energy Technology Data Exchange (ETDEWEB)

    FEDOTOV, A.V.

    2005-03-18

    Studies of beam halo became unavoidable feature of high-intensity machines where uncontrolled beam loss should be kept to extremely small level. For a well controlled stable beam such a loss is typically associated with the low density halo surrounding beam core. In order to minimize uncontrolled beam loss or improve performance of an accelerator, it is very important to understand what are the sources of halo formation in a specific machine of interest. The dominant mechanisms are, in fact, different in linear accelerators, circular machines or Energy Recovering Linacs (ERL). In this paper, we summarize basic mechanisms of halo formation in high-intensity beams and discuss their application to various types of accelerators of interest, such as linacs, rings and ERL.

  6. Beam chopper development at LAMPF

    International Nuclear Information System (INIS)

    Hutson, R.L.; Cooke, D.W.; Heffner, R.H.; Schillaci, M.E.; Dodds, S.A.; Gist, G.A.

    1986-01-01

    In order to reduce pileup limitations on μSR data rates, a fast chopper for surface muon beams was built and tested at LAMPF. The system allowed one muon at a time to be stopped in a μSR sample in the following way: A surface beam from the LAMPF Stopped Muon Channel was focused through a crossed-field beam separator and onto a chopper slit. With the separator E and B fields adjusted properly, the beam could pass through the slit. The beam to the μSR sample was turned on or off (chopped) rapidly by switching the high voltage applied to the separator plates on or off within approximately 500 ns; with the E field off, the B field deflected the beam, dumping it near the slit. We demonstrated that, with improved electronics, we will be able to stop a single muon in a μSR sample as frequently as once every 20 μs and that data rates for the system can be a factor of five higher than is attainable with unchopped beams. The observed positron contamination of the beam was less than five percent, and the ratio of the muon rate with beam on to the rate with beam off was 1540

  7. On beam quality and flatness of radiotherapy megavoltage photon beams

    International Nuclear Information System (INIS)

    Hossain, Murshed; Rhoades, Jeffrey

    2016-01-01

    Ratio of percentage depth dose (PDD) at two depths, PDD at a depth of 10 cm (PDD 10 ), and beam flatness are monitored regularly for radiotherapy beams for quality assurance. The purpose of this study is to understand the effects of changes in one of these parameters on the other. Is it possible to monitor only the beam flatness and not PDD? The investigation has two components. Naturally occurring i.e., unintended changes in PDD ratio and in-plane flatness for 6 and 10 MV photon beams for one particular Siemens Artiste Linac are monitored for a period of about 4 years. Secondly, deliberate changes in the beam parameters are induced by changing the bending magnet current (BMI). Relationships between various beam parameters for unintended changes as well as deliberate changes are characterized. Long term unintentional changes of PDD ratio are found to have no systematic trend. The flatness in the in plane direction for 6 and 10 MV beams show slow increase of 0.43 and 0.75 % respectively in about 4 years while the changes in the PDD ratio show no such trend. Over 10 % changes in BMI are required to induce changes in the beam quality indices at 2 % level. PDD ratio for the 10 MV beam is found to be less sensitive, while the depth of maximum dose, d max , is more sensitive to the changes in BMI compared to the 6 MV beam. Tolerances are more stringent for PDD 10 than PDD ratio for the 10 MV beam. PDD ratio, PDD 10 , and flatness must be monitored independently. Furthermore, off axis ratio alone cannot be used to monitor flatness. The effect of beam quality change in the absolute dose is clinically insignificant.

  8. Beam position monitor for energy recovered linac beams

    Energy Technology Data Exchange (ETDEWEB)

    Powers, Thomas; Evtushenko, Pavel

    2017-06-06

    A method of determining the beam position in an energy recovered linac (ERL). The method makes use of in phase and quadrature (I/Q) demodulation techniques to separate the pickup signal generated by the electromagnetic fields generated by the first and second pass beam in the energy recovered linac. The method includes using analog or digital based I/Q demodulation techniques in order to measure the relative amplitude of the signals from a position sensitive beam pickup such as a button, strip line or microstripline beam position monitor.

  9. Constraints on ion beam handling for intersecting beam experiments

    International Nuclear Information System (INIS)

    Kruse, T.

    1981-01-01

    The intense synchrotron radiation beams from the NSLS uv or x-ray storage rings still do not compare in monochromatized photon flux with a laser beam, a fact which becomes apparent in considering reaction rates for interaction of photon and ion beams. There are two prototypical interaction geometries, parallel and perpendicular. Calculations should properly be done in the rest frame of the ion beam; however, expected beta values are small, so the lab frame will be employed and aberration and Doppler shift effects neglected

  10. Beam-beam collisions and crossing angles in RHIC

    International Nuclear Information System (INIS)

    Peggs, S.

    1999-01-01

    This paper evaluates the strength of head on and parasitic beam-beam collisions in RHIC when the crossing angle is zero. A non-zero crossing angle is not required in normal operation with 120 bunches, thanks to the early separation of the two beams. The RHIC lattice is shown to easily accommodate even conservatively large crossing angles, for example in beam dynamics studies, or in future operational upgrades to as many as 360 bunches per ring. A modest loss in luminosity is incurred when gold ions collide at an angle after 10 hours of storage

  11. Beam-beam tails simulation for KEK B-factory

    International Nuclear Information System (INIS)

    Shatilov, D.

    1996-12-01

    The special tracking technique is applied for investigation of the beam-beam interaction for KEK B-factory with a crossing angle at the IP. This technique allows us to save a lot of CPU time while simulating the beam tails. The detailed comparison with the brute force tracking code has been performed in order to confirm the validity of the technique. After that, some simulation results for KEKB are presented, which have shown that, in spite of synchro-betatron resonances induced by a crossing angle at the IP, the beam halo growing is quite acceptable. (author)

  12. Optics and beam guidance

    International Nuclear Information System (INIS)

    De Conto, Jean-Marie

    2002-01-01

    This is an introductory manual for the field of particle transport (guiding). The utilized method described is that of classical geometrical optics which is based on the action principle or minimal action principle. This manual is addressed to readers neither specialized or familiar with intricate computations. The treatment is focussed upon the transport line of an experimental beam conceived for the late-project PIAFE. This case was chosen as it poses and solves certain significant difficult issues. In addition it will also allow in course of exposition to illustrate formulas and properties and also to give orders of magnitude. Background notions are given on: forces, curvature radius, potential, energy and units. The frame of conception is defined by means of the concepts of particle, referential trajectory, emittance, quadrupoles, electrostatic lenses, etc. Simulation for a large number of systems can be done with fairly high accuracy with the aid of thin lenses. Consequently the properties of several assemblies as for instance the periodic system 'FODO' are studied on the case of a single particle and emittance by means of adaptation and stability notions. The manual is structured on the following sections: 1. Introduction; 2. Basic notions; 3. Particle trajectories; 4. The real beam. Emittance and Evolution; 5.Optics notions and applications; 6. Elements of focusing; 7. Particle beam bending; 8. Some items presented in annexes and conclusions. In annexes the following important technical issues are addressed: 1. Effects of alignment failures on PIAFE structure trajectories; 2. Alignment. Phase 1: Magnetic centers and quadrupoles; 3. Alignment. Phase 2: Structures; 4. Residual gas/ Required pressure

  13. Microplanar beams for radiotherapy

    International Nuclear Information System (INIS)

    Company, F.Z.; Allen, B.J.

    1996-01-01

    Recent advances in synchrotron generated X-ray beams with high fluence rate permit the investigation of the application of an array of closely spaced, parallel or converging microbeams in radiotherapy. The proposed technique takes advantage of the hypothesised repair mechanism of capillary cells between alternate microbeam zones, which replaces the lethally irradiated endothelial cells. In this study using the Monte Carlo method, the lateral and depth dose of a single planar microbeam of 100 keV in a tissue/lung/tissue phantom is investigated. Poster 195. (author)

  14. Dynamic acoustic tractor beams

    Energy Technology Data Exchange (ETDEWEB)

    Mitri, F. G., E-mail: F.G.Mitri@ieee.org [Chevron, Area 52 Technology – ETC, Santa Fe, New Mexico 87508 (United States)

    2015-03-07

    Pulling a sphere and vibrating it around an equilibrium position by amplitude-modulation in the near-field of a single finite circular piston transducer is theoretically demonstrated. Conditions are found where a fluid hexane sphere (with arbitrary radius) chosen as an example, centered on the axis of progressive propagating waves and submerged in non-viscous water, experiences an attractive (steady) force pulling it towards the transducer, as well as an oscillatory force forcing it to vibrate back-and-forth. Numerical predictions for the dynamic force illustrate the theory and suggest an innovative method in designing dynamic acoustical tractor beams.

  15. Beam shaping for relay mirrors

    Science.gov (United States)

    Mansell, Justin D.

    2006-08-01

    Relay mirrors offer a method of extending the range and efficacy of laser weapons systems by providing a platform that can relay the high power beam from the source to a target at a lower cost than building more laser weapons. Most laser weapons' platforms use a Cassegrain aperture telescope to project the high-power beam to a target. Diffraction causes power in the projected beam to move out beyond the edge of the receiving aperture and into the central obscuration of the receiving Cassegrain telescope. This paper presents a method of increasing the power coupling between a projected beam and a receiving telescope by warping the phase of the projected beam and shows that the spatial frequency and amplitude of the phase aberration is consistent with being integrated with the adaptive optics control loop on the source beam projector.

  16. eRHIC Beam Scrubbing

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, S. Y. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2017-06-22

    We propose using beam scrubbing to mitigate the electron cloud e ect in the eRHIC. The bunch number is adjusted below the heat load limit, then it increases with the reduced secondary electron yield resulted from the beam scrubbing, up to the design bunch number. Since the electron density threshold of beam instability is lower at the injection, a preliminary injection scrubbing should go rst, where large chromaticity can be used to keep the beam in the ring for scrubbing. After that, the beam can be ramped to full energy, allowing physics scrubbing. Simulations demonstrated that with beam scrubbing in a reasonable period of time, the eRHIC baseline design is feasible.

  17. Smartphone laser beam spatial profiler.

    Science.gov (United States)

    Hossain, Md Arafat; Canning, John; Cook, Kevin; Jamalipour, Abbas

    2015-11-15

    A simple, low-cost, portable, smartphone-based laser beam profiler for characterizing laser beam profiles is reported. The beam profiler utilizes a phosphor silica glass plate to convert UV light into visible (green) light that can be directly imaged onto an existing smartphone CMOS chip and analyzed using a customized app. 3D printing enables the ready fabrication of the instrument package. The beam's diameter, shape, divergence, beam quality factor, and output power are measured for two UV lasers: a CW 244 nm frequency-doubled Ar ion laser and a pulsed 193 nm ArF exciplex laser. The availability of specialized phosphor converters can extend the instrument from the UV to the near infrared and beyond, and the smartphone platform extends the Internet of Things to map laser beam profiles simultaneously in different locations.

  18. NCenter wide band neutrino beam

    International Nuclear Information System (INIS)

    Stutte, L.G.

    1985-01-01

    This memo describes the physical properties of the currently operating N-Center wide band neutrino beam---commonly called the triplet train, following a past tradition of a triplet lens configuration. In reality, in order to gain a larger momentum acceptance and to minimize the angular divergence of the beam, a quadruplet beam (4 lenses) employing point-to-parallel optics at a central momentum of 300 GeV was built. 6 refs., 13 figs., 1 tab

  19. A pencil beam algorithm for helium ion beam therapy.

    Science.gov (United States)

    Fuchs, Hermann; Strobele, Julia; Schreiner, Thomas; Hirtl, Albert; Georg, Dietmar

    2012-11-01

    To develop a flexible pencil beam algorithm for helium ion beam therapy. Dose distributions were calculated using the newly developed pencil beam algorithm and validated using Monte Carlo (MC) methods. The algorithm was based on the established theory of fluence weighted elemental pencil beam (PB) kernels. Using a new real-time splitting approach, a minimization routine selects the optimal shape for each sub-beam. Dose depositions along the beam path were determined using a look-up table (LUT). Data for LUT generation were derived from MC simulations in water using GATE 6.1. For materials other than water, dose depositions were calculated by the algorithm using water-equivalent depth scaling. Lateral beam spreading caused by multiple scattering has been accounted for by implementing a non-local scattering formula developed by Gottschalk. A new nuclear correction was modelled using a Voigt function and implemented by a LUT approach. Validation simulations have been performed using a phantom filled with homogeneous materials or heterogeneous slabs of up to 3 cm. The beams were incident perpendicular to the phantoms surface with initial particle energies ranging from 50 to 250 MeV/A with a total number of 10(7) ions per beam. For comparison a special evaluation software was developed calculating the gamma indices for dose distributions. In homogeneous phantoms, maximum range deviations between PB and MC of less than 1.1% and differences in the width of the distal energy fall off of the Bragg-Peak from 80% to 20% of less than 0.1 mm were found. Heterogeneous phantoms using layered slabs satisfied a γ-index criterion of 2%/2mm of the local value except for some single voxels. For more complex phantoms using laterally arranged bone-air slabs, the γ-index criterion was exceeded in some areas giving a maximum γ-index of 1.75 and 4.9% of the voxels showed γ-index values larger than one. The calculation precision of the presented algorithm was considered to be sufficient

  20. Isomeric Targets and Beams

    International Nuclear Information System (INIS)

    Oganesyan, Yu.Ts.; Karamyan, S.A.

    1994-01-01

    One of the main topics of modern nuclear physics is the investigation of exotic nuclei including hyper-nuclei, trans fermium elements, proton and neutron rich isotopes near drip lines as well as high-spin excited states and states with anomalous deformation. The isomerism of nuclei is closely related with such phenomena as the alignment of single-particle orbitals, the coexistence of various deformations and the manifestation of intruder-levels from neighbouring shells. The investigation of electromagnetic and nuclear interactions of isomers could give important information on their shell structure and its role in the mechanism of nuclear reactions. For such experiments one can either make isomeric targets (sufficiently long-lived) or use the methods of acceleration of isomeric nuclei. Recently, an exotic 16 + four-quasiparticle isomer of 178 Hf m 2 was produced in a micro weight quantity and the first nuclear reactions on it were successfully observed. The talk describes these experiments as well as new ideas for the continuation of the studies and some advantageous ways for the isomeric beams production by the method of direct acceleration or by the secondary beam method. 35 refs., 15 figs., 8 tabs

  1. Proton beam source

    International Nuclear Information System (INIS)

    Auslender, V.L.; Lazarev, V.N.; Panfilov, A.D.

    1979-01-01

    A proton pulse source with penning discharge and a cathode needle in the discharge chamber is described. The source is simple in design and has a great service life. An electromagnet induces a magnetic field of the order of 700 Oe along the axis of the discharge chamber. In this field the discharge is ignited between the left and right cathodes when a positive voltage is applied to the anode. A hole in the recess of the right cathode serves to provide the injection of plasma into the accelerating gap. The cathodes and the anode unit are set into a sleeve welded to magnet poles. Through a magnetic circuit this unit is placed on a high-voltage ceramic insulator. For extraction and initial shaping of an ion beam with a divergence angle of 3 0 use is made of extraction electrodes which form the Pierce optics. Further shaping of the ion beam is realized by an electrostatic lens. Tungsten grids in the holes of grounded electrodes increase the focusing effect of the lens. At the input of the first accelerating gap of an accelerator the described source provides an ion peak current of 140 mA at 65% content of protons and a normalized emittance of no more than 4x10 -5 cmxrad

  2. Molecular beam kinetics

    International Nuclear Information System (INIS)

    Behrens, R. Jr.

    1975-11-01

    The design of a crossed molecular beam ''supermachine'' for neutral--neutral collisions is discussed. The universal electron bombardment ionizer, mass filter, and ion detection system of the detector, the supersonic nozzle sources, the differential pumping arrangement for the sources and detector, the time-of-flight detection of scattered products, and the overall configuration of the apparatus are described. The elastic scattering of two systems, CH 4 + Ar and NH 3 + Ar, has been measured using the supermachine with two supersonic nozzle sources. The rainbow structure and the interference oscillations are seen in each system. The best fit to the data was found using a Morse--Spline--Van der Waals (MSV) potential. The three potential parameters epsilon, r/sub m/, and β were found to be 2.20(+-0.04) x 10 -14 ergs, 3.82(+-0.04)A, and 7.05 +- 0.20 for CH 4 + Ar, and 2.21(+-0.04) x 10 -14 ergs 3.93 (+-0.05)A, and 8.45 +- 0.30 for NH 3 + Ar. A new phenomenon in crossed molecular beams of condensation of a molecule on a cluster to form a complex was observed. A bromine molecule condensed on clusters of chlorine (Cl 2 )/sub chi/ and ammonia (NH 3 )/sub chi/. The value of chi for measurements in these experiments ranges from 7 to 40 for chlorine clusters and from 10 to 70 ammonia clusters

  3. Monochromatic neutrino beams

    CERN Document Server

    Bernabeu, J; Espinoza, C; Lindroos, M

    2005-01-01

    In the last few years spectacular results have been achieved with the demonstration of non vanishing neutrino masses and flavour mixing. The ultimate goal is the understanding of the origin of these properties from new physics. In this road, the last unknown mixing [Ue3] must be determined. If it is proved to be non-zero, the possibility is open for Charge Conjugation-Parity (CP) violation in the lepton sector. This will require precision experiments with a very intense neutrino source. Here a novel method to create a monochromatic neutrino beam, an old dream for neutrino physics, is proposed based on the recent discovery of nuclei that decay fast through electron capture. Such nuclei will generate a monochromatic directional neutrino beam when decaying at high energy in a storage ring with long straight sections. We also show that the capacity of such a facility to discover new physics is impressive, so that fine tuning of the boosted neutrino energy allows precision measurements of the oscillation parameter...

  4. Monochromatic neutrino beams

    International Nuclear Information System (INIS)

    Bernabeu, Jose; Burguet-Castell, Jordi; Espinoza, Catalina; Lindroos, Mats

    2005-01-01

    In the last few years spectacular results have been achieved with the demonstration of non vanishing neutrino masses and flavour mixing. The ultimate goal is the understanding of the origin of these properties from new physics. In this road, the last unknown mixing [U e3 ] must be determined. If it is proved to be non-zero, the possibility is open for Charge Conjugation-Parity (CP) violation in the lepton sector. This will require precision experiments with a very intense neutrino source. Here a novel method to create a monochromatic neutrino beam, an old dream for neutrino physics, is proposed based on the recent discovery of nuclei that decay fast through electron capture. Such nuclei will generate a monochromatic directional neutrino beam when decaying at high energy in a storage ring with long straight sections. We also show that the capacity of such a facility to discover new physics is impressive, so that fine tuning of the boosted neutrino energy allows precision measurements of the oscillation parameters even for a [U e3 ] mixing as small as 1 degree. We can thus open a window to the discovery of CP violation in neutrino oscillations

  5. Beam based alignment at LEP

    CERN Document Server

    Dehning, Bernd; Mugnai, G; Reichel, I; Schmidt, R; Sonnemann, F; Tecker, F A

    2004-01-01

    We describe a beam-based method for finding the relative offset between beam position monitors (BPMs) and the magnetic centres of the adjacent quadrupole magnets. The strength of a given quadrupole is modulated and the induced closed orbit oscillation measured for different beam positions, reaching a minimum when the beam is centred in the quadrupole. The BPM reading at this point is a measure of its offset, which may be determined at LEP with an accuracy of ~40x10-6 m.

  6. Funneling of heavy ion beams

    International Nuclear Information System (INIS)

    Bongardt, K.; Karlsruhe Univ.; Sanitz, D.

    1982-01-01

    The funneling of heavy ion beams can be achieved by first bending the beams by septum magnets towards the common axis, and then deflecting them onto the axis by rf-deflector elements with time varying electric field strength. The main properties of these deflection elements are discussed, especially the increase of the transverse emittance. As an example beam envelopes are shown for funneling two 100 mA, 1.7 MEV/N Bisup(+2) beams into one 108 MHz Alvarez accelerator. (orig.)

  7. Beam distribution function after filamentation

    Energy Technology Data Exchange (ETDEWEB)

    Raubenheimer, T.O.; Decker, F.J.; Seeman, J.T.

    1995-05-01

    In this paper, the authors calculate the beam distribution function after filamentation (phase-mixing) of a focusing mismatch. This distribution is relevant when interpreting beam measurements and sources of emittance dilution in linear colliders. It is also important when considering methods of diluting the phase space density, which may be required for the machine protection system in future linear colliders, and it is important when studying effects of trapped ions which filament in the electron beam potential. Finally, the resulting distribution is compared with measured beam distributions from the SLAC linac.

  8. Status of ACCULINNA beam line

    CERN Document Server

    Rodin, A M; Bogdanov, D D; Golovkov, M S; Fomichev, A S; Sidorchuk, S I; Slepnev, R S; Wolski, R; Ter-Akopian, G M; Oganessian, Yu T; Yukhimchuk, A A; Perevozchikov, V V; Vinogradov, Yu I; Grishenchkin, S K; Demin, A M; Zlatoustovskii, S V; Kuryakin, A V; Filchagin, S V; Ilkaev, R I

    2003-01-01

    The separator ACCULINNA was upgraded to achieve new experimental requirements. The beam line was extended by new ion-optical elements beyond the cyclotron hall. The new arrangements yield much better background conditions. The intensities of sup 6 He and sup 8 He radioactive beams produced in fragmentation of 35 A MeV sup 1 sup 1 B ions were increased up to a factor of 10. The upgraded beam line was used in experiments to study the sup 5 H resonance states populated in the t+t reaction. A cryogenic liquid tritium target was designed and installed at the separator beam line.

  9. Electron beam-cured coating

    International Nuclear Information System (INIS)

    Kishi, Naoyuki

    1976-01-01

    The method for hardening coatings by the irradiation with electron beams is reviewed. The report is divided into seven parts, namely 1) general description and characteristics of electron beam-cured coating, 2) radiation sources of curing, 3) hardening conditions and reaction behaviour, 4) uses and advantages, 5) latest trends of the industry, 6) practice in the field of construction materials, and 7) economy. The primary characteristics of the electron beam hardening is that graft reaction takes place between base resin and coating to produce strong adhesive coating without any pretreatment. A variety of base resins are developed. High class esters of acrylic acid monomers and methacrylic acid monomers are mainly used as dilutants recently. At present, scanning type accelerators are used, but the practical application of the system producing electron beam of curtain type is expected. The dose rate dependence, the repetitive irradiation and the irradiation atmosphere are briefly described. The filed patent applications on the electron beam hardening were analyzed by the officer of Japan Patent Agency. The production lines for coatings by the electron beam hardening in the world are listed. In the electron beam-cured coating, fifty percent of given energy is consumed effectively for the electron beam hardening, and the solvents discharged from ovens and polluting atmosphere are not used, because the paints of high solid type is used. The running costs of the electron beam process are one sixth of the thermal oven process. (Iwakiri, K.)

  10. Ion beam assisted film growth

    CERN Document Server

    Itoh, T

    2012-01-01

    This volume provides up to date information on the experimental, theoretical and technological aspects of film growth assisted by ion beams.Ion beam assisted film growth is one of the most effective techniques in aiding the growth of high-quality thin solid films in a controlled way. Moreover, ion beams play a dominant role in the reduction of the growth temperature of thin films of high melting point materials. In this way, ion beams make a considerable and complex contribution to film growth. The volume will be essential reading for scientists, engineers and students working in thi

  11. 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.

  12. Beam Diagnostics for Low-Intensity Radioactive Beams

    CERN Document Server

    Cosentino, L

    2001-01-01

    In order to perform imaging, profiling and identification of low intensity (Ibeam5 pps) Radioactive Ion Beams (RIB), we have developed a series of diagnostics devices, operating in a range of beam energy from 50 keV up to 8 MeV/A. These characteristics do them especially suitable for ISOL RIB facilities.

  13. Tevatron beam-beam simulations at injection energy

    Energy Technology Data Exchange (ETDEWEB)

    Meiqin Xiao; Bela Erdelyi; Tanaji Sen

    2003-05-28

    Major issues at Tevatron injection are the effects of 72 long-range beam-beam interactions together with the machine nonlinearity on protons and anti-protons. We look at particle tracking calculations of Dynamic Aperture (DA) under present machine conditions. Comparisons of calculations with observations and experiments are also presented in this report.

  14. Overview of Beam-Beam Effects in the Tevatron

    CERN Document Server

    Shiltsev, V.

    2014-01-01

    For almost a quarter of a century the Tevatron proton-antiproton collider was the centrepiece of the world's high-energy physics program, from the start of operation in December 1985 until it was overtaken by the LHC in 2011. The initial design luminosity of the Tevatron was 1030 cm-2 s-1; however, as a result of two decades of upgrades, the accelerator has been able to deliver 430-times higher luminosities to each of two high-luminosity experiments, Collider Detector at Fermilab (CDF) and D0. On the way to record high luminosities, many issues related to the electromagnetic beam-beam interaction of colliding beams have been addressed. Below we present a short overview of the beam-beam effects in the Tevatron.

  15. Tuning the beam: a physics perspective on beam diagnostic instrumentation

    Energy Technology Data Exchange (ETDEWEB)

    Gulley, Mark S [Los Alamos National Laboratory

    2010-01-01

    In a nutshell, the role of a beam diagnostic measurement is to provide information needed to get a particle beam from Point A (injection point) to Point B (a target) in a useable condition, with 'useable' meaning the right energy and size and with acceptable losses. Specifications and performance requirements of diagnostics are based on the physics of the particle beam to be measured, with typical customers of beam parameter measurements being the accelerator operators and accelerator physicists. This tutorial will be a physics-oriented discussion of the interplay between tuning evolutions and the beam diagnostics systems that support the machine tune. This will include the differences between developing a tune and maintaining a tune, among other things. Practical longitudinal and transverse tuning issues and techniques from a variety of proton and electron machines will also be discussed.

  16. Development of neutral beam source using electron beam excited plasma

    International Nuclear Information System (INIS)

    Hara, Yasuhiro; Hamagaki, Manabu; Mise, Takaya; Hara, Tamio

    2011-01-01

    A low-energy neutral beam (NB) source, which consists of an electron-beam-excited plasma (EBEP) source and two carbon electrodes, has been developed for damageless etching of ultra-large-scale integrated (ULSI) devices. It has been confirmed that the Ar ion beam energy was controlled by the acceleration voltage and the beam profile had good uniformity over the diameter of 80 mm. Dry etching of a Si wafer at the floating potential has been carried out by Ar NB. Si sputtering yield by an Ar NB clearly depends on the acceleration voltage. This result shows that the NB has been generated through the charge exchange reaction from the ion beam in the process chamber. (author)

  17. Beam-beam synchrobetatron resonance at the LHC

    CERN Document Server

    OHMI, K

    2012-01-01

    Some beam-beam simulations are presented for the LHC beam parameters of late 2012, with collisions at nonzero crossing angle in IPs 1 and 5. Long-range encounters and other IPs are not included. Strong emittance growth is observed above 3the -rd order resonance. Synchrotron motion and z dependent beam-beam force, in particular the nonzero crossing angle, are essential ingredients for this growth. Bunch shortening is observed simultaenously with the strong transverse emittance growth, which is consistent with LHC observations in November 2012. The simulations do not show any significant growth close to the 7-th order resonance ~0.29. The simulated bunch shortening at 3Qy~1is sensitive to Qx. Open questions are if the tune of some bunches may exceed 0.33 in LHC, and/or whether electron cloud also contributes to the phenomenon. This presentation was given at CERN on 4 December 2012.

  18. Asymmetric Bessel-Gauss beams.

    Science.gov (United States)

    Kotlyar, V V; Kovalev, A A; Skidanov, R V; Soifer, V A

    2014-09-01

    We propose a three-parameter family of asymmetric Bessel-Gauss (aBG) beams with integer and fractional orbital angular momentum (OAM). The aBG beams are described by the product of a Gaussian function by the nth-order Bessel function of the first kind of complex argument, having finite energy. The aBG beam's asymmetry degree depends on a real parameter c≥0: at c=0, the aBG beam is coincident with a conventional radially symmetric Bessel-Gauss (BG) beam; with increasing c, the aBG beam acquires a semicrescent shape, then becoming elongated along the y axis and shifting along the x axis for c≫1. In the initial plane, the intensity distribution of the aBG beams has a countable number of isolated optical nulls on the x axis, which result in optical vortices with unit topological charge and opposite signs on the different sides of the origin. As the aBG beam propagates, the vortex centers undergo a nonuniform rotation with the entire beam about the optical axis (c≫1), making a π/4 turn at the Rayleigh range and another π/4 turn after traveling the remaining distance. At different values of the c parameter, the optical nulls of the transverse intensity distribution change their position, thus changing the OAM that the beam carries. An isolated optical null on the optical axis generates an optical vortex with topological charge n. A vortex laser beam shaped as a rotating semicrescent has been generated using a spatial light modulator.

  19. Design and Analysis Methodologies for Inflated Beams

    NARCIS (Netherlands)

    Veldman, S.L.

    2005-01-01

    The central theme of the thesis is bending behaviour of inflated beams. Three different types of beams have been analysed for the bending load case: a straight cylindrical beam made of anisotropic foil material, a conical beam made of an isotropic foil material, and a carbon fibre braided beam. The

  20. DELTA beam position monitor

    International Nuclear Information System (INIS)

    Brinker, S.; Heisterhagen, R.; Wille, K.

    1991-01-01

    For the electron storage ring DELTA (Dortmund ELectron Test Accelerator) a beam-position-monitor system based on button pickups has been designed. Two different concepts for the monitor electronics have been developed obtaining a long-term stability better than ± 150 μm and a short-term resolution below ± 10 μm. There are no hybrids integrated in the electronic circuits as all four button signals should be amplified and digitized to provide redundancy. First, a concept using four separated electronic branches, one for each button, was tested. Then a concept with a multiplexer in front followed by only one amplifier was designed. This concept, the electronic circuits and the measurements are presented

  1. Laser beam accelerator

    International Nuclear Information System (INIS)

    Tajima, T.; Dawson, J.M.

    1981-01-01

    Parallel intense photon (laser, microwave, etc.) beams /omega/sub //0, k/sub 0/ and /omega/sub //1, k/sub 1/ shone on a plasma with frequency separation equal to the plasma frequency /omega/sub //p is capable of accelerating plasma electrons to high energies in large flux. The photon beat excites through the forward Raman scattering large amplitude plasmons whose phase velocity is equal to (/omega/ /sub 0/-/omega/sub //1)/(k/sub 0/-k/sub 1/), close to c in an underdense plasma. The multiple forward Raman instability produces smaller and smaller frequency and group velocity of photons; thus the photons slow down in the plasma by emitting accelerated electrons (inverse Cherenkov process). 6 refs

  2. Mechanically reinforced glass beams

    DEFF Research Database (Denmark)

    Nielsen, Jens Henrik; Olesen, John Forbes

    2007-01-01

    The use of glass as a load carrying material in structural elements is rarely seen even though glass is a popular material for many architects. This is owed to the unreliable and low tensile strength, which is due to surface flaws and high brittleness of the material. These properties lead...... to breakage without any warning or ductility, which can be catastrophic if no precautions are taken. One aspect of this issue is treated here by looking at the possibility of mechanically reinforcing glass beams in order to obtain ductile failure for such a structural component. A mechanically reinforced...... presented. The experiments show that it is possible to obtain a very ductile structural behavior using the right amount of reinforcement. A Finite Element Model including - in a simple manner - the effects of cracking of glass is presented. Based on a comparison between experimental and model results...

  3. Neutron beam measurement dosimetry

    International Nuclear Information System (INIS)

    Amaro, C.R.

    1995-01-01

    This report describes animal dosimetry studies and phantom measurements. During 1994, 12 dogs were irradiated at BMRR as part of a 4 fraction dose tolerance study. The animals were first infused with BSH and irradiated daily for 4 consecutive days. BNL irradiated 2 beagles as part of their dose tolerance study using BPA fructose. In addition, a dog at WSU was irradiated at BMRR after an infusion of BPA fructose. During 1994, the INEL BNCT dosimetry team measured neutron flux and gamma dose profiles in two phantoms exposed to the epithermal neutron beam at the BMRR. These measurements were performed as a preparatory step to the commencement of human clinical trials in progress at the BMRR

  4. Molecular-beam scattering

    International Nuclear Information System (INIS)

    Vernon, M.F.

    1983-07-01

    The molecular-beam technique has been used in three different experimental arrangements to study a wide range of inter-atomic and molecular forces. Chapter 1 reports results of a low-energy (0.2 kcal/mole) elastic-scattering study of the He-Ar pair potential. The purpose of the study was to accurately characterize the shape of the potential in the well region, by scattering slow He atoms produced by expanding a mixture of He in N 2 from a cooled nozzle. Chapter 2 contains measurements of the vibrational predissociation spectra and product translational energy for clusters of water, benzene, and ammonia. The experiments show that most of the product energy remains in the internal molecular motions. Chapter 3 presents measurements of the reaction Na + HCl → NaCl + H at collision energies of 5.38 and 19.4 kcal/mole. This is the first study to resolve both scattering angle and velocity for the reaction of a short lived (16 nsec) electronic excited state. Descriptions are given of computer programs written to analyze molecular-beam expansions to extract information characterizing their velocity distributions, and to calculate accurate laboratory elastic-scattering differential cross sections accounting for the finite apparatus resolution. Experimental results which attempted to determine the efficiency of optically pumping the Li(2 2 P/sub 3/2/) and Na(3 2 P/sub 3/2/) excited states are given. A simple three-level model for predicting the steady-state fraction of atoms in the excited state is included

  5. CLIC Drive Beam Accelerating Structures

    CERN Document Server

    Wegner, Rolf

    2012-01-01

    Travelling structures for accelerating the high-current (4.2 A) CLIC Drive Beam to an energy of 2.37 GeV are presented. The structures are optimised for efficiency (full beam loading operation) and a desired filling time. Higher order modes are studied and are reduced by detuning along the structure and by damping with silicon carbide loads.

  6. Novel electron beam recording media

    International Nuclear Information System (INIS)

    1974-01-01

    Electron beam recording media comprise a film of an olefin-SO 2 copolymer on a support. Certain of these copolymers give direct print-out relief patterns after exposure to electron beams. The chemical composition and preparation of these layered films is described

  7. Hybrid beams in the LHC

    CERN Multimedia

    CERN Bulletin

    2011-01-01

    The first proton-ion beams were successfully circulated in the LHC a couple of weeks ago. Everything went so smoothly that the LHC teams had planned the first p-Pb collisions for Wednesday, 16 November. Unfortunately, a last-minute problem with a component of the PS required for proton acceleration prevented the LHC teams from making these new collisions. However, the way is open for a possible physics run with proton-lead collisions in 2012.   Members of the LHC team photographed when the first hybrid beams got to full energy. The proton and lead beams are visible on the leftmost screen up on the wall (click to enlarge the photo). The technical challenge of making different beams circulate in the LHC is by no means trivial. Even if the machine is the same, there are a number of differences when it is operated with beams of protons, beams of lead or beams of proton and lead. Provided that the beams are equal, irrespective of whether they consist of protons or lead nuclei, they revolve at the...

  8. NETWORK CODING BY BEAM FORMING

    DEFF Research Database (Denmark)

    2013-01-01

    Network coding by beam forming in networks, for example, in single frequency networks, can provide aid in increasing spectral efficiency. When network coding by beam forming and user cooperation are combined, spectral efficiency gains may be achieved. According to certain embodiments, a method...

  9. Intense nonrelativistic cesium ion beam

    International Nuclear Information System (INIS)

    Lampel, M.C.

    1984-01-01

    The Heavy Ion Fusion group at Lawrence Berkeley Laboratory has constructed the One Ampere Cesium injector as a proof of principle source to supply an induction linac with a high charge density and high brightness ion beam. This is studied here. An electron beam probe was developed as the major diagnostic tool for characterizing ion beam space charge. Electron beam probe data inversion is accomplished with the EBEAM code and a parametrically adjusted model radial charge distribution. The longitudinal charge distribution was not derived, although it is possible to do so. The radial charge distribution that is derived reveals an unexpected halo of trapped electrons surrounding the ion beam. A charge fluid theory of the effect of finite electron temperature on the focusing of neutralized ion beams (Nucl Fus. 21, 529(1981)) is applied to the problem of the cesium beam final focus at the end of the injector. It is shown that the theory's predictions and assumptions are consistent with the experimental data, and that it accounts for the observed ion beam radius of approx.5 cm and the electron halo, including the determination of an electron Debye length of approx.10 cm

  10. Introduction to electron beam processing

    International Nuclear Information System (INIS)

    Waichiro Kawakami

    1994-01-01

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

  11. First LHC beam in 2017

    CERN Multimedia

    ATLAS Collaboration

    2017-01-01

    Impressions from the ATLAS control room while waiting for the very first 2017 LHC beams, from the traditional croissants in the morning to the "beam splashes" in the evening. The shift crew, online experts, run coordinators and management are looking forward the next steps of the LHC restart.

  12. Radioactive beams and their applications

    International Nuclear Information System (INIS)

    Rudchik, A.T.

    1992-01-01

    The proceedings contain lectures and contributed papers submitted to the second INR (Kiev's) International School on Nuclear Physics (Kiev, June 25 -July 2, 1991). The following sections were included in the Proceedings: Radioactive Beam Facilities, Application of Radioactive Beams in the Investigations of Nuclear Reactions, Exotic Nuclei and Clusters, Polarization Phenomena, Astrophysics and Others

  13. Dark matter beams at LBNF

    Energy Technology Data Exchange (ETDEWEB)

    Coloma, Pilar; Dobrescu, Bogdan A.; Frugiuele, Claudia; Harnik, Roni [Theory Department, Fermi National Accelerator Laboratory,P.O. Box 500, Batavia, IL 60510 (United States)

    2016-04-08

    High-intensity neutrino beam facilities may produce a beam of light dark matter when protons strike the target. Searches for such a dark matter beam using its scattering in a nearby detector must overcome the large neutrino background. We characterize the spatial and energy distributions of the dark matter and neutrino beams, focusing on their differences to enhance the sensitivity to dark matter. We find that a dark matter beam produced by a Z{sup ′} boson in the GeV mass range is both broader and more energetic than the neutrino beam. The reach for dark matter is maximized for a detector sensitive to hard neutral-current scatterings, placed at a sizable angle off the neutrino beam axis. In the case of the Long-Baseline Neutrino Facility (LBNF), a detector placed at roughly 6 degrees off axis and at a distance of about 200 m from the target would be sensitive to Z{sup ′} couplings as low as 0.05. This search can proceed symbiotically with neutrino measurements. We also show that the MiniBooNE and MicroBooNE detectors, which are on Fermilab’s Booster beamline, happen to be at an optimal angle from the NuMI beam and could perform searches with existing data. This illustrates potential synergies between LBNF and the short-baseline neutrino program if the detectors are positioned appropriately.

  14. Device for electron beam machining

    International Nuclear Information System (INIS)

    Panzer, S.; Ardenne, T. von; Liebergeld, H.

    1984-01-01

    The invention concerns a device for electron beam machining, in particular welding. It is aimed at continuous operation of the electron irradiation device. This is achieved by combining the electron gun with a beam guiding chamber, to which vacuum chambers are connected. The working parts to be welded can be arranged in the latter

  15. Beam phase space and emittance

    International Nuclear Information System (INIS)

    Buon, J.

    1990-12-01

    The classical and elementary results for canonical phase space, the Liouville theorem and the beam emittance are reviewed. Then, the importance of phase portraits to obtain a geometrical description of motion is emphasized, with examples in accelerator physics. Finally, a statistical point of view is used to define beam emittance, to study its law of approximate conservation and to treat two particular examples

  16. Harmonic vibrations of multispan beams

    DEFF Research Database (Denmark)

    Dyrbye, Claes

    1996-01-01

    Free and forced harmonic vibrations of multispan beams are determined by a method which implies 1 equation regardless of the configuration. The necessary formulas are given in the paper. For beams with simple supports and the same length of all (n) spans, there is a rather big difference between...

  17. Maximum entropy beam diagnostic tomography

    International Nuclear Information System (INIS)

    Mottershead, C.T.

    1985-01-01

    This paper reviews the formalism of maximum entropy beam diagnostic tomography as applied to the Fusion Materials Irradiation Test (FMIT) prototype accelerator. The same formalism has also been used with streak camera data to produce an ultrahigh speed movie of the beam profile of the Experimental Test Accelerator (ETA) at Livermore. 11 refs., 4 figs

  18. Beam dynamics for induction accelerators

    International Nuclear Information System (INIS)

    Lee, Edward P.

    2014-01-01

    An induction linac uses pulsed power that is applied directly, without any intervening resonant cavities, to accelerate a charged particle pulse. This approach can accommodate a large multiple-beam focusing lattice capable of transporting a large total beam current with a long pulse duration, which may be compressed while accelerating as well as afterward. The mean accelerating gradient is relatively low (less than about 1.5 MV/m), but the potential efficiency of energy transfer can be large up to about 50%. A multiple-beam induction linac is therefore a natural candidate accelerator for a heavy ion fusion (HIF) driver. However, the accelerated beams must meet stringent requirements on occupied phase space volume in order to be focused accurately and with small radius onto the fusion target. Dynamical considerations in the beam injector and linac, as well as in the final compression, final focus, and the fusion chamber, determine the quality of the driver beams as they approach the target. Requirements and tolerances derived from beam dynamics strongly influence the linac configuration and component design. After a summary of dynamical considerations, two major topics are addressed here: transportable current limits, which determine the choice of focal system for the linac, and longitudinal control of the beams, which are potentially destabilized by their interaction with the pulsed power system

  19. Toward automated beam optics control

    International Nuclear Information System (INIS)

    Silbar, R.R.; Schultz, D.E.

    1987-01-01

    We have begun a program aiming toward automatic control of charged-particle beam optics using artificial intelligence programming techniques. In developing our prototype, we are working with LISP machines and the KEE expert system shell. Our first goal was to develop a ''mouseable'' representation of a typical beam line. This responds actively to changes entered from the mouse or keyboard, giving an updated display of the beam line itself, its optical properties, and the instrumentation and control devices as seen by the operater. We have incorporated TRANSPORT, written in Fortran but running as a callable procedure in the LISP environment, for simulation of the beam-line optics. This paper describes the experience gained in meeting our first goal and discusses plans to extend the work so that it is usable, in realtime, on an operating beam line. 11 refs

  20. Solitary waves in particle beams

    International Nuclear Information System (INIS)

    Bisognano, J.J.

    1996-01-01

    Since space charge waves on a particle beam exhibit both dispersive and nonlinear character, solitary waves or solitons are possible. Dispersive, nonlinear wave propagation in high current beams is found to be similar to ion-acoustic waves in plasmas with an analogy between Debye screening and beam pipe shielding. Exact longitudinal solitary wave propagation is found for potentials associated with certain transverse distributions which fill the beam pipe. For weak dispersion, the waves satisfy the Korteweg-deVries (KdV) equation, but for strong dispersion they exhibit breaking. More physically realizable distributions which do not fill the beam pipe are investigated and shown to also satisfy a KdV equation for weak dispersion if averaging over rapid transverse motion is physically justified. Scaling laws are presented to explore likely parameter regimes where these phenomena may be observed experimentally

  1. Beam line windows at LAMPF

    International Nuclear Information System (INIS)

    Brown, R.D.; Grisham, D.L.; Lambert, J.E.

    1985-01-01

    The A-6 main beam-line window at LAMPF separates the vacuum of the main beam line from the isotope production station, proton irradiation ports, and the beam stop, which operate in air. This window must withstand the design beam current of 1 mA at 800 MeV for periods of at least 3000 hours without failure. The window is water cooled and must be strong enough to withstand the 2.1 MPa (300 psig) cooling water pressure, as well as beam-induced thermal stresses. Two designs have been used to meet these goals, a stepped-plate window and a hemispherical window, both made from a precipitation-hardened nickel base alloy, Alloy 718. Calculations of the temperatures and stresses in each of these windows are presented

  2. An introduction to beam physics

    CERN Document Server

    Berz, Martin; Wan, Weishi

    2015-01-01

    The field of beam physics touches many areas of physics, engineering, and the sciences. In general terms, beams describe ensembles of particles with initial conditions similar enough to be treated together as a group so that the motion is a weakly nonlinear perturbation of a chosen reference particle. Particle beams are used in a variety of areas, ranging from electron microscopes, particle spectrometers, medical radiation facilities, powerful light sources, and astrophysics to large synchrotrons and storage rings such as the LHC at CERN. An Introduction to Beam Physics is based on lectures given at Michigan State University’s Department of Physics and Astronomy, the online VUBeam program, the U.S. Particle Accelerator School, the CERN Academic Training Programme, and various other venues. It is accessible to beginning graduate and upper-division undergraduate students in physics, mathematics, and engineering. The book begins with a historical overview of methods for generating and accelerating beams, high...

  3. Design of HELIOS beam diagnostics

    International Nuclear Information System (INIS)

    Seagrave, J.D.; Bigio, I.J.; Jackson, S.V.; Laird, A.M.

    1979-01-01

    Verification of satisfactory operation of the HELIOS eight-beam laser system requires measurement of many parameters of each beam on each shot. Fifty-joule samples of each of the eight 1250-J, subnanosecond 34-cm-diameter beams of the HELIOS system are diverted to a gallery of eight folded telescopes and beamsplit to provide diagnostic measurements. Total pulse energy, and prepulse and postlase energy of each beam are measured; pulse shape details and a wavelength spectrum of a selected beam from each shot are measured; and provision is made for retropulse measurement and optical quality monitoring. All data are recorded digitally in a local screen room, with control and communication through a fiberoptic link to the main HELIOS computer

  4. Broad-band beam buncher

    International Nuclear Information System (INIS)

    Goldberg, D.A.; Flood, W.S.; Arthur, A.A.; Voelker, F.

    1986-01-01

    This patent describes a broad-band beam buncher. This beam buncher consists of: a housing adapted to be eacuated, an electron gun in the housing for producing a beam of electrons, buncher means in the housing forming a buncher cavity which has an entrance opening for receiving the electron beam and an exit opening through which the electron beam passes out of the buncher cavity, a drift tube electrode in the buncher cavity and disposed between the entrance opening and the exit opening with first and second gaps between the drift tube electrode and the entrance and exit openings, the drift tube electrode which has a first drift space through which the electron beam passes in traveling between the entrance and exit openings, modulating means for supplying an ultrahigh frequeny modulating signal to the drift tube electrode for producing velocity modulation of the electrons in the electron beam as the electrons pass through the buncher cavity and the drift tube electrode between the entrance opening and the exit opening, drift space means in the housing forming a second drift space for receiving the velocity modulated electron beam from the exit opening, the velocity modulated electron beam being bunched as it passes along the second drift space, the drift space means has a discharge opening through which the electron beam is discharged from the second drift space after being bunched therein, the modulating means containing a signal source for producing an ultrahigh frequency signal, a transmission line connected between the signal source and the drift tube electrode, and terminating means connected to the drift tube electrode for terminating the transmission line in approximately its characteristic impedance to afford a broad response band with minimum 6 variations therein

  5. Optimal beam forming for laser beam propagation through random media

    Science.gov (United States)

    Liu, Baoyong

    Focusing optical beams on a target through random propagation media is very important in many applications such as free space optical communications and laser weapons. Random media effects such as beam spread and scintillation can degrade the optical system's performance severely. Compensation schemes are needed in these applications to overcome these random media effects. In this research, we investigated the optimal beams for two different optimization criteria: one is to maximize the concentrated received intensity and the other is to minimize the scintillation index at the target plane. In the study of the optimal beam to maximize the weighted integrated intensity, we derive a similarity relationship between pupil-plane phase screen and extended Huygens-Fresnel model, and demonstrate the limited utility of maximizing the average integrated intensity. In the study of the optimal beam to minimize the scintillation index, we derive the first- and second-order moments for the integrated intensity of multiple coherent modes. Hermite-Gaussian and Laguerre-Gaussian modes are used as the coherent modes to synthesize an optimal partially coherent beam. The optimal beams demonstrate evident reduction of scintillation index, and prove to be insensitive to the aperture averaging effect.

  6. A Refined Zigzag Beam Theory for Composite and Sandwich Beams

    Science.gov (United States)

    Tessler, Alexander; Sciuva, Marco Di; Gherlone, Marco

    2009-01-01

    A new refined theory for laminated composite and sandwich beams that contains the kinematics of the Timoshenko Beam Theory as a proper baseline subset is presented. This variationally consistent theory is derived from the virtual work principle and employs a novel piecewise linear zigzag function that provides a more realistic representation of the deformation states of transverse-shear flexible beams than other similar theories. This new zigzag function is unique in that it vanishes at the top and bottom bounding surfaces of a beam. The formulation does not enforce continuity of the transverse shear stress across the beam s cross-section, yet is robust. Two major shortcomings that are inherent in the previous zigzag theories, shear-force inconsistency and difficulties in simulating clamped boundary conditions, and that have greatly limited the utility of these previous theories are discussed in detail. An approach that has successfully resolved these shortcomings is presented herein. Exact solutions for simply supported and cantilevered beams subjected to static loads are derived and the improved modelling capability of the new zigzag beam theory is demonstrated. In particular, extensive results for thick beams with highly heterogeneous material lay-ups are discussed and compared with corresponding results obtained from elasticity solutions, two other zigzag theories, and high-fidelity finite element analyses. Comparisons with the baseline Timoshenko Beam Theory are also presented. The comparisons clearly show the improved accuracy of the new, refined zigzag theory presented herein over similar existing theories. This new theory can be readily extended to plate and shell structures, and should be useful for obtaining relatively low-cost, accurate estimates of structural response needed to design an important class of high-performance aerospace structures.

  7. On nonlinear development of beam instability

    International Nuclear Information System (INIS)

    Popel', S.I.; Tsytovich, V.N.

    1990-01-01

    Radiation-resonance interactions are taken into account in the problem of dynamics of an electron beam inb plasma. The beam characteristics to be taken into account are determined. Stabilization conditions for beam instability are established

  8. A beam profile monitor for small electron beams

    International Nuclear Information System (INIS)

    Norem, J.

    1991-01-01

    Measurement of beam properties at the foci of high energy linacs is difficult due to the small size of the waists in proposed and existing accelerators (1 nm - 2 μ). This paper considers the use of bremsstrahlung radiation from thin foils to measure the size and phase space density these beams using nonimaging optics. The components of the system are described, and the ultimate resolution, evaluated theoretically for the case of the Final Focus Test Beam at Stanford Linear Accelerator Center, is a few nm. 13 refs., 4 figs. 1 tab

  9. OBSERVATION OF STRONG - STRONG AND OTHER BEAM - BEAM EFFECTS IN RHIC

    International Nuclear Information System (INIS)

    FISCHER, W.; BLASKIEWICZ, M.; BRENNAN, J.M.; CAMERON, P.; CONNOLLY, R.; MONTAG, C.; PEGGS, S.; PILAT, F.; PTITSYN, V.; TEPIKIAN, S.; TRBOJEVIC, D.; VAN ZEIJTS, J.

    2003-01-01

    RHIC is currently the only hadron collider in which strong-strong beam-beam effects can be seen. For the first time, coherent beam-beam modes were observed in a bunched beam hadron collider. Other beam-beam effects in RHIC were observed in operation and in dedicated experiments with gold ions, deuterons and protons. Observations include measurements of beam-beam induced tune shifts, lifetime and emittance growth measurements with and without beam-beam interaction, and background rates as a function of tunes. During ramps unequal radio frequencies in the two rings cause the crossing points to move longitudinally. Thus bunches experience beam-beam interactions only in intervals and the tunes are modulated. In this article we summarize the most important beam-beam observations made so far

  10. Coherent instabilities of a relativistic bunched beam

    International Nuclear Information System (INIS)

    Chao, A.W.

    1982-06-01

    A charge-particle beam contained in an accelerator vacuum chamber interacts electromagnetically with its environment to create a wake field. This field than acts back on the beam, perturbing the particle motion. If the beam intensity is high enough, this beam-environment interaction may lead to an instability and to subsequent beam loss. The beam and its environment form a dynamical system, and it is this system that will be studied. 84 references

  11. Coherent instabilities of a relativistic bunched beam

    Energy Technology Data Exchange (ETDEWEB)

    Chao, A.W.

    1982-06-01

    A charge-particle beam contained in an accelerator vacuum chamber interacts electromagnetically with its environment to create a wake field. This field than acts back on the beam, perturbing the particle motion. If the beam intensity is high enough, this beam-environment interaction may lead to an instability and to subsequent beam loss. The beam and its environment form a dynamical system, and it is this system that will be studied. 84 references.

  12. Heavy charged-particle beam dosimetry

    International Nuclear Information System (INIS)

    Lyman, J.T.

    1982-06-01

    A computational description of the physical properties and the beam composition of a heavy charged-particle beam is presented. The results with this beam model has been compared with numerous sets of experimental data and it appears to provide an adequate representation of the major features of a heavy charged-particle beam. Knowledge of the beam composition aids in the identification of regions of the beam where special dosimetry problems may be encountered

  13. Ultra-High Density Electron Beams for Beam Radiation and Beam Plasma Interaction

    CERN Document Server

    Anderson, Scott; Frigola, Pedro; Gibson, David J; Hartemann, Fred V; Jacob, Jeremy S; Lim, Jae; Musumeci, Pietro; Rosenzweig, James E; Travish, Gil; Tremaine, Aaron M

    2005-01-01

    Current and future applications of high brightness electron beams, which include advanced accelerators such as the plasma wake-field accelerator (PWFA) and beam-radiation interactions such as inverse-Compton scattering (ICS), require both transverse and longitudinal beam sizes on the order of tens of microns. Ultra-high density beams may be produced at moderate energy (50 MeV) by compression and subsequent strong focusing of low emittance, photoinjector sources. We describe the implementation of this method used at LLNL's PLEIADES ICS x-ray source in which the photoinjector-generated beam has been compressed to 300 fsec duration using the velocity bunching technique and focused to 20 μm rms size using an extremely high gradient, permanent magnet quadrupole (PMQ) focusing system.

  14. Spacecraft ion beam noise effects

    Science.gov (United States)

    Anenberg, G. L.

    1972-01-01

    An estimate of the antenna noise temperature and the uplink signal-to-noise ratio has been made for Bremsstrahlung radiation emitted by a spacecraft ion beam; a worst-case situation in which the spacecraft antenna is located in the exit plane of the ion beam and directed at varying angles into the ion beam is assumed. Numerical results of the antenna noise temperature versus antenna pointing angle are given for a typical set of ion beam and antenna pattern parameters. The uplink signal-to-noise ratio due to the ion beam noise alone is given in terms of a critical range in AU at which a typical ranging transmission is received with S/N = 0 db. The effects of the ion beam divergence angle and antenna distance on the ion beam are also presented. Results of the study show typical increases in the antenna noise temperature of about 0.2 K and critical ranges of the order of 3-5 AU. An ion engine thus generally introduces an undetectable level of noise into a spacecraft receiver.

  15. Nuclear physics with radioactive beams

    International Nuclear Information System (INIS)

    Bimbot, R.

    1994-01-01

    Radioactive beams can be produced through two different and complementary ways:i. the production at rest of radioactive nuclei, followed by their acceleration using conventional techniques.This method is the best for producing low energy radioactive beams. ii. the fragmentation of high energy heavy ion beams ( over 30 MeV/u), followed by the selection and purification of a given secondary beam using magnetic spectrometers. This technique leads to high energy radioactive beams. Both methods have now been used in several laboratories in the world. Examples of the corresponding experimental equipment will be presented, and especially Lise 3, Sissi, and the spiral project at GANIL. Radioactive beams have used for several purposes in nuclear physics: i. they constitute the fastest technique ever used for transferring exotic nuclei from the production point to a well shielded place where detectors can be operated for studying their properties in good conditions. At the same time, they can be identified using solid state detectors and the time-of-flight/energy-loss technique. Illustrations of the results obtained in this domain (mass and half-life measurements, recent identification of the isotope sup 1 sup 0 sup 0 Sn) is given. ii. they are used to induce nuclear reactions which may bring new information on nuclear structure. For example, the measurement of total reaction cross-sections for many radioactive projectiles revealed the existence of halo nuclei such as sup 1 sup 1 Li and sup 1 sup 1 Be. Beams of these isotopes have been extensively used to precise their structure.iii. in the domain of nuclear astrophysics, radioactive beams are used to measure, through direct or indirect methods, the cross sections for reactions of crucial interest in nucleosynthesis. Finally, radioactive beams of light positron emitters, such as sup 1 sup 9 Ne have considerable interest for medical purposes and especially in the growing field of heavy-ion radiotherapy. 8 figs., 24 refs

  16. Numerical simulation of electron beam welding with beam oscillations

    Science.gov (United States)

    Trushnikov, D. N.; Permyakov, G. L.

    2017-02-01

    This research examines the process of electron-beam welding in a keyhole mode with the use of beam oscillations. We study the impact of various beam oscillations and their parameters on the shape of the keyhole, the flow of heat and mass transfer processes and weld parameters to develop methodological recommendations. A numerical three-dimensional mathematical model of electron beam welding is presented. The model was developed on the basis of a heat conduction equation and a Navier-Stokes equation taking into account phase transitions at the interface of a solid and liquid phase and thermocapillary convection (Marangoni effect). The shape of the keyhole is determined based on experimental data on the parameters of the secondary signal by using the method of a synchronous accumulation. Calculations of thermal and hydrodynamic processes were carried out based on a computer cluster, using a simulation package COMSOL Multiphysics.

  17. Beam profile effects on NPB [neutral particle beam] performance

    International Nuclear Information System (INIS)

    LeClaire, R.J. Jr.

    1988-03-01

    A comparison of neutral particle beam brightness for various neutral beam profiles indicates that the widely used assumption of a Gaussian profile may be misleading for collisional neutralizers. An analysis of available experimental evidence shows that lower peaks and higher tails, compared to a Gaussian beam profile, are observed out of collisional neutralizers, which implies that peak brightness is over estimated, and for a given NPB platform-to-target range, the beam current (power), dwell time or some combination of such engagement parameters would have to be altered to maintain a fixed dose on target. Based on the present analysis, this factor is nominally about 2.4 but may actually be as low as 1.8 or as high as 8. This is an important consideration in estimating NPB constellation performance in SDI engagement contexts. 2 refs., 6 figs

  18. Simulating Transient Effects of Pulsed Beams on Beam Intercepting Devices

    CERN Document Server

    Richter, Herta; Noah Messomo, Etam

    2011-01-01

    The development in the physics community towards higher beam power through the possibilities of particle accelerators lead to challenges for the developers of elements which are exposed to effect of particle beams (beam intercepting devices = BIDs). For the design of BIDs, the increasing heat load onto these devices due to energetic and focused beams and - in most cases - their highly pulsed nature has to be taken into account. The physics requirements are sometimes opposed to the current state of the art. As one possibility of many in combining the different aspects for these ambitious demands, two highly developed computer programs, namely FLUKA and ANSYS AUTODYN, were joined for this dissertation. The former is a widely enhanced Monte-Carlo-code which specializes on the interaction of particles with static matter, while the latter is a versatile explicit code for the simulation of highly dynamic processes. Both computer programs were developed intensively over years and are still continuously enhanced in o...

  19. A Symplectic Beam-Beam Interaction with Energy Change

    Energy Technology Data Exchange (ETDEWEB)

    Moshammer, Herbert

    2003-07-14

    The performance of many colliding storage rings is limited by the beam-beam interaction. A particle feels a nonlinear force produced by the encountering bunch at the collision. This beam-beam force acts mainly in the transverse directions so that the longitudinal effects have scarcely been studied, except for the cases of a collision with a crossing angle. Recently, however, high luminosity machines are being considered where the beams are focused extensively at the interaction point (IP) so that the beam sizes can vary significantly within the bunch length. Krishnagopal and Siemann have shown that they should not neglect the bunch length effect in this case. The transverse kick depends on the longitudinal position as well as on the transverse position. If they include this effect, however, from the action-reaction principle, they should expect, at the same time, an energy change which depends on the transverse coordinates. Such an effect is reasonably understood from the fact that the beam-beam force is partly due to the electric field, which can change the energy. The action-reaction principle comes from the symplecticity of the reaction: the electromagnetic influence on a particle is described by a Hamiltonian. The symplecticity is one of the most fundamental requirements when studying the beam dynamics. A nonsymplectic approximation can easily lead to unphysical results. In this paper, they propose a simple, approximately but symplectic mapping for the beam-beam interaction which includes the energy change as well as the bunch-length effect. In the next section, they propose the mapping in a Hamiltonian form, which directly assures its symplecticity. Then in section 3, they study the nature of the mapping by interpreting its consequences. The mapping itself is quite general and can be applied to any distribution function. They show in Section 4 how it appears when the distribution function is a Gaussian in transverse directions. The mapping is applied to the

  20. Beam Transfer and Machine Protection

    CERN Document Server

    Kain, V

    2016-01-01

    Beam transfer, such as injection into or extraction from an accelerator, is one of the most critical moments in terms of machine protection in a high-intensity machine. Special equipment is used and machine protection aspects have to be taken into account in the design of the beam transfer concepts. A brief introduction of the principles of beam transfer and the equipment involved will be given in this lecture. The main concepts of machine protection for injection and extraction will be presented, with examples from the CERN SPS and LHC.

  1. Standard beam PWC for Fermilab

    International Nuclear Information System (INIS)

    Fenker, H.

    1983-02-01

    As one of its projects the Fermilab Experimental Areas Department has been designed and tested a relatively small proportional wire chamber for use in the secondary beam lines. It is intended to supplement the variety of detectors known in the vernacular as SWICS that are used to obtain profiles for beam tuning. The new detector, described in this report, operates in the limited proportional mode and allows experimenters to use a standard, lab supported device for associating trajectories of individual beam particles with events triggering their own experiment's apparatus. A completed triple plane module is shown

  2. Plural beam electron gun assembly

    International Nuclear Information System (INIS)

    Stratton, M.G.

    1977-01-01

    The invention relates to a cathode ray tube plural-beam-in-line bi-potential electron gun assembly, having applied beam currents of differing levels, manifests structurally modified gun structures to effect focused beam landings at the screen that are evidenced as substantially equi-sized spots thereby providing improved resolution and brightness of the screen imagery. The structural changes embody modifications of the related focusing and accelerator electrodes of the respective guns to provide a partial telescoping arrangement for effecting the discrete placement, forming and shielding of the final focusing lenses. The three lenses so formed are in different planes in partial overlapping axial relationship

  3. Beam based systems and controls

    CERN Document Server

    Jacquet, D

    2012-01-01

    This presentation will give a review from the operations team of the performance and issues of the beam based systems, namely RF, ADT, beam instrumentation, controls and injection systems. For each of these systems, statistics on performance and availability will be presented with the main issues encountered in 2012. The possible improvements for operational efficiency and safety will be discussed, with an attempt to answer the question "Are we ready for the new challenges brought by the 25ns beam and increased energy after LSI? ".

  4. Intense beams of light ions

    International Nuclear Information System (INIS)

    Camarcat, Noel

    1985-01-01

    Results of experiments performed in order to accelerate intense beams of light and heavier ions are presented. The accelerating diodes are driven by existing pulsed power generators. Optimization of the generator structure is described in chapter I. Nuclear diagnostics of the accelerated light ion beams are presented in chapter II. Chapter III deals with the physics of intense charged particle beams. The models developed are applied to the calculation of the performances of the ion diodes described in the previous chapters. Chapter IV reports preliminary results on a multiply ionized carbon source driven by a 0.1 TW pulsed power generator. (author) [fr

  5. Spectrum analysis in beam diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, S.Y.; Weng, W.T.

    1993-04-23

    In this article, we discuss fundamentals of the spectrum analysis in beam diagnostics, where several important particle motions in a circular accelerator are considered. The properties of the Fourier transform are presented. Then the coasting and the bunched beam motion in both longitudinal and transverse are studied. The discussions are separated for the signal particle, multiple particle, and the Schottky noise cases. To demonstrate the interesting properties of the beam motion spectrum, time domain functions are generated, and then the associated spectra are calculated and plotted. In order to show the whole picture in a single plot, some data have been scaled, therefore they may not be realistic in an accelerator.

  6. Noninterceptive transverse-beam measurements

    International Nuclear Information System (INIS)

    Chamberlin, D.D.; Minerbo, G.N.; Mottershead, C.T.

    1981-01-01

    Totally noninterceptive techniques for accurate measurement of transverse beam distributions are required for high-current continuous wave (cw) linacs, such as the Fusion Materials Irradiation Test (FMIT) accelerator. Sensors responding to visible radiation from beam interactions with residual gas and computer algorithms reconstructing spatial and phase space distributions have been implemented. This paper reports on early measurements of the beam from the injector of the prototype FMIT facility at Los Alamos. The first section indicates hardware setup and performance whereas the second section describes the data-processing software. The third section outlines the resultant measurements and further developments are discussed in the fourth section

  7. Positronium reflection and positronium beams

    International Nuclear Information System (INIS)

    Weber, M.; Tang, S.; Khatri, R.; Roellig, L.O.; Viescas, A.J.; Berko, S.; Canter, K.F.; Lynn, K.G.; Mills, A.P. Jr.

    1989-01-01

    We have observed specular reflection of positronium, Ps, and established that there is adequate intensity at higher energies to make further study worthwhile. The scattering appears to be restricted to the outermost surface with a mean free path of (0.75 ± 0.15)Angstrom for Ps in LiF(100). With a greater intensity Ps beam one should see higher order diffraction beams as the result of the periodicity of the surface. Ps diffraction thus offers the possibility of being a novel and valuable probe to study the outermost surface and to study adsorbents on it. Two methods for producing Ps beams are described. 29 refs., 11 figs

  8. CEBAF beam viewer imaging software

    International Nuclear Information System (INIS)

    Bowling, B.A.; McDowell, C.

    1993-01-01

    This paper discusses the various software used in the analysis of beam viewer images at CEBAF. This software, developed at CEBAF, includes a three-dimensional viewscreen calibration code which takes into account such factors as multiple camera/viewscreen rotations and perspective imaging, and maintaining a calibration database for each unit. Additional software allows single-button beam spot detection, with determination of beam location, width, and quality, in less than three seconds. Software has also been implemented to assist in the determination of proper chopper RF control parameters from digitized chopper circles, providing excellent results

  9. Beam phase space and emittance

    International Nuclear Information System (INIS)

    Buon, J.

    1992-02-01

    The classical and elementary results for canonical phase space, the Liouville theorem and the beam emittance are reviewed. Then, the importance of phase portraits to obtain a geometrical description of motion is emphasized, with examples in accelerator physics. Finally, a statistical point of view is used to define beam emittance, to study its law of approximate conservation, with three particular examples, and to introduce a beam envelope-ellipse and the β-function, emphasing the statistical features of its properties. (author) 14 refs.; 11 figs

  10. BR2 reactor neutron beams

    International Nuclear Information System (INIS)

    Neve de Mevergnies, M.

    1977-01-01

    The use of reactor neutron beams is becoming increasingly more widespread for the study of some properties of condensed matter. It is mainly due to the unique properties of the ''thermal'' neutrons as regards wavelength, energy, magnetic moment and overall favorable ratio of scattering to absorption cross-sections. Besides these fundamental reasons, the impetus for using neutrons is also due to the existence of powerful research reactors (such as BR2) built mainly for nuclear engineering programs, but where a number of intense neutron beams are available at marginal cost. A brief introduction to the production of suitable neutron beams from a reactor is given. (author)

  11. Generation of arbitrary vector beams

    Science.gov (United States)

    Perez-Garcia, Benjamin; López-Mariscal, Carlos; Hernandez-Aranda, Raul I.; Gutiérrez-Vega, Julio C.

    2017-08-01

    Optical vector beams arise from point to point spatial variations of the electric component of an electromagnetic field over the transverse plane. In this work, we present a novel experimental technique to generate arbitrary vec- tor beams, and provide sufficient evidence to validate their state of polarization. This technique takes advantage of the capability of a Spatial Light Modulator to simultaneously generate two components of an electromagnetic field by halving the screen of the device and subsequently recombining them in a Sagnac interferometer. Our experimental results show the versatility and robustness of this technique for the generation of vector beams.

  12. Sheet Beam Klystron Instability Analysis

    International Nuclear Information System (INIS)

    Bane, K.

    2009-01-01

    Using the principle of energy balance we develop a 2D theory for calculating growth rates of instability in a two-cavity model of a sheet beam klystron. An important ingredient is a TE-like mode in the gap that also gives a longitudinal kick to the beam. When compared with a self-consistent particle-in-cell calculation, with sheet beam klystron-type parameters, agreement is quite good up to half the design current, 65 A; at full current, however, other, current-dependent effects come in and the results deviate significantly

  13. Gamma ray beam transmutation

    International Nuclear Information System (INIS)

    Imasaki, K.; Li, D.; Miyamoto, S.; Amano, S.; Motizuki, T.

    2007-01-01

    We have proposed a new approach to nuclear transmutation by a gamma ray beam of Compton scattered laser photon. We obtained 20 MeV gamma ray in this way to obtain transmutation rates with the giant resonance of 1 97Au and 1 29Iodine. The rate of the transmutation agreed with the theoretical calculation. Experiments on energy spectrum of positron, electron and neutron from targets were performed for the energy balance and design of the system scheme. The reaction rate was about 1.5∼4% for appropriate photon energies and neutron production rate was up to 4% in the measurements. We had stored laser photon more than 5000 times in a small cavity which implied for a significant improvement of system efficiency. Using these technologies, we have designed an actual transmutation system for 1 29Iodine which has a 16 million year's activity. In my presentation, I will address the properties of this scheme, experiments results and transmutation system for iodine transmutation

  14. Beam based measurement of beam position monitor electrode gains

    OpenAIRE

    D. L. Rubin; M. Billing; R. Meller; M. Palmer; M. Rendina; N. Rider; D. Sagan; J. Shanks; C. Strohman

    2010-01-01

    Low emittance tuning at the Cornell Electron Storage Ring (CESR) test accelerator depends on precision measurement of vertical dispersion and transverse coupling. The CESR beam position monitors (BPMs) consist of four button electrodes, instrumented with electronics that allow acquisition of turn-by-turn data. The response to the beam will vary among the four electrodes due to differences in electronic gain and/or misalignment. This variation in the response of the BPM electrodes will couple ...

  15. Doppler-shifted neutral beam line shape and beam transmission

    Energy Technology Data Exchange (ETDEWEB)

    Kamperschroer, J.H.; Grisham, L.R.; Kokatnur, N.; Lagin, L.J.; Newman, R.A.; O`Connor, T.E.; Stevenson, T.N.; von Halle, A.

    1994-04-01

    Analysis of Doppler-shifted Balmer-{alpha} line emission from the TFTR neutral beam injection systems has revealed that the line shape is well approximated by the sum of two Gaussians, or, alternatively, by a Lorentzian. For the sum of two Gaussians, the broad portion of the distribution contains 40% of the beam power and has a divergence five times that of the narrow part. Assuming a narrow 1/e- divergence of 1.3{degrees} (based on fits to the beam shape on the calorimeter), the broad part has a divergence of 6.9{degrees}. The entire line shape is also well approximated by a Lorentzian with a half-maximum divergence of 0.9{degrees}. Up to now, fusion neutral beam modelers have assumed a single Gaussian velocity distribution, at the extraction plane, in each direction perpendicular to beam propagation. This predicts a beam transmission efficiency from the ion source to the calorimeter of 97%. Waterflow calorimetry data, however, yield a transmission efficiency of {approximately}75%, a value in rough agreement with predictions of the Gaussian or Lorentzian models presented here. The broad wing of the two Gaussian distribution also accurately predicts the loss in the neutralizer. An average angle of incidence for beam loss at the exit of the neutralizer is 2.2{degrees}, rather than the 4.95{degrees} subtended by the center of the ion source. This average angle of incidence, which is used in computing power densities on collimators, is shown to be a function of beam divergence.

  16. Doppler-shifted neutral beam line shape and beam transmission

    International Nuclear Information System (INIS)

    Kamperschroer, J.H.; Grisham, L.R.; Kokatnur, N.; Lagin, L.J.; Newman, R.A.; O'Connor, T.E.; Stevenson, T.N.; von Halle, A.

    1994-04-01

    Analysis of Doppler-shifted Balmer-α line emission from the TFTR neutral beam injection systems has revealed that the line shape is well approximated by the sum of two Gaussians, or, alternatively, by a Lorentzian. For the sum of two Gaussians, the broad portion of the distribution contains 40% of the beam power and has a divergence five times that of the narrow part. Assuming a narrow 1/e- divergence of 1.3 degrees (based on fits to the beam shape on the calorimeter), the broad part has a divergence of 6.9 degrees. The entire line shape is also well approximated by a Lorentzian with a half-maximum divergence of 0.9 degrees. Up to now, fusion neutral beam modelers have assumed a single Gaussian velocity distribution, at the extraction plane, in each direction perpendicular to beam propagation. This predicts a beam transmission efficiency from the ion source to the calorimeter of 97%. Waterflow calorimetry data, however, yield a transmission efficiency of ∼75%, a value in rough agreement with predictions of the Gaussian or Lorentzian models presented here. The broad wing of the two Gaussian distribution also accurately predicts the loss in the neutralizer. An average angle of incidence for beam loss at the exit of the neutralizer is 2.2 degrees, rather than the 4.95 degrees subtended by the center of the ion source. This average angle of incidence, which is used in computing power densities on collimators, is shown to be a function of beam divergence

  17. Beam-Beam Simulations with GUINEA-PIG

    CERN Document Server

    Schulte, Daniel

    1998-01-01

    While the bunches in a linear collider cross only once, due to their small size they experience a strong beam-beam effect. GUINEA-PIG is a code to simulate the impact of this effect on luminosity and back ground. A short overview of the program is given with examples of its application to the back ground strudies for TESLA, the top quark threshold scan and a possible luminosity monitor, as well as some results for CLIC.

  18. Beam loading effects for two-beam ring

    International Nuclear Information System (INIS)

    Wang Lanfa; Lin Yuzheng; Tong Dechun

    1999-01-01

    An analytic treatment of multi-bunch potential well distortion for a two-beam storage ring is presented. The longitudinal wake effects are separated into: the mode loss, the synchrotron tune shift (both due to potential well distortion) and the coherent multi-bunch coupling. Here, only the first two effects are studied. Resulting simple analytic formulas describe the mode loss and the synchrotron tune shift experienced by a given bunch within the two-beam, as a function of the high order mode's parameters. One can get immediately a simple quantitative answer in term of the mode loss and the synchrotron tune shift experienced by each bunch from these formulas, so the authors can know how to modify the existing configuration of parasitic cavity resonance (via frequency tuning) so that the resulting potential well distortion effects are minimized. When the RF cavities are symmetrically distributed about the interaction points, the two beams will have same beam loading effects, so the authors can compensate the phase shift of the two beam using the same method as in one beam case

  19. Experimental observations and theoretical models for beam-beam phenomena

    International Nuclear Information System (INIS)

    Kheifets, S.

    1981-03-01

    The beam-beam interaction in storage rings exhibits all the characteristics of nonintegrable dynamical systems. Here one finds all kinds of resonances, closed orbits, stable and unstable fixed points, stochastic layers, chaotic behavior, diffusion, etc. The storage ring itself being an expensive device nevertheless while constructed and put into operation presents a good opportunity of experimentally studying the long-time behavior of both conservative (proton machines) and nonconservative (electron machines) dynamical systems - the number of bunch-bunch interactions routinely reaches values of 10 10 -10 11 and could be increased by decreasing the beam current. At the same time the beam-beam interaction puts practical limits for the yield of the storage ring. This phenomenon not only determines the design value of main storage ring parameters (luminosity, space charge parameters, beam current), but also in fact prevents many of the existing storage rings from achieving design parameters. Hence, the problem has great practical importance along with its enormous theoretical interest. A brief overview of the problem is presented

  20. Test Beam Coordination: 2003 ATLAS Combined Test Beam

    CERN Multimedia

    Di Girolamo, B.

    The 2003 Test Beam Period The 2003 Test Beam period has been very fruitful for ATLAS. In spite of several days lost because of the accelerator problems, ATLAS has been able to achieve many results: FCAL has completed the calibration program in H6 Tilecal has completed the calibration program in H8 Pixel has performed extensive studies with normal and high intensity beams (up to 1.4*108 hadrons/spill) SCT has completed a variety of studies with quite a high number of modules operated concurrently TRT has performed several studies at high, low and very low energy (first use of the new H8 beam in the range 1 to 9 GeV) Muons (MDT,RPC and TGC) have been operating a large setup for about 5 months. The almost final MDT ROD (MROD) has been integrated in the readout and the final trigger electronics for TGC and RPC has been tested and certified with normal beam and during dedicated 40 MHz beam periods. The TDAQ has exploited a new generation prototype successfully and the new Event Filter infrastructure f...

  1. Observations and open questions in beam-beam interactions

    International Nuclear Information System (INIS)

    Sen, Tanaji

    2010-01-01

    The first of the hadron colliders, ISR, started operation in 1970. In the following years, the hadron colliders to follow were the SPS (started 1980), the Tevatron (started 1987 first as a fixed target machine), RHIC (started 2000) and most recently the LHC, which started in 2008. HERA was a hybrid that collided electrons and protons. All of these accelerators had or have their performance limited by the effects of the beam-beam interactions. That has also been true for the electron-positron colliders such as LEP, CESR, KEKB and PEPII. In this article I will discuss how the beam-beam limitations arose in some of these machines. The discussion will be focused on common themes that span the different colliders. I will mostly discuss the hadron colliders but sometimes discuss the lepton colliders where relevant. Only a handful of common accelerator physics topics are chosen here, the list is not meant to be exhaustive. A comparative review of beam-beam performance in the ISR, SPS and Tevatron (ca 1989) can be found in reference. Table 1 shows the relevant parameters of colliders (excluding the LHC), which have accelerated protons.

  2. Tutorial on beam current monitoring

    International Nuclear Information System (INIS)

    Webber, Robert C.

    2000-01-01

    This paper is a tutorial level review covering a wide range of aspects related to charged particle beam current measurement. The tutorial begins with a look at the characteristics of the beam as a signal source, the associated electromagnetic fields, the influence of the typical accelerator environment on those fields, and the usual means of modifying and controlling that environment to facilitate beam current measurement. Short descriptions of three quite different types of current monitors are presented and a quantitative review of the classical transformer circuit is given. Recognizing that environmental noise pick-up may present a large source of error in quantitative measurements, signal handling considerations are given considerable attention using real-life examples. An example of a successful transport line beam current monitor implementation is presented and the tutorial concludes with a few comments about signal processing and current monitor calibration issues

  3. Libera Electron Beam Position Processor

    CERN Document Server

    Ursic, Rok

    2005-01-01

    Libera is a product family delivering unprecedented possibilities for either building powerful single station solutions or architecting complex feedback systems in the field of accelerator instrumentation and controls. This paper presents functionality and field performance of its first member, the electron beam position processor. It offers superior performance with multiple measurement channels delivering simultaneously position measurements in digital format with MHz kHz and Hz bandwidths. This all-in-one product, facilitating pulsed and CW measurements, is much more than simply a high performance beam position measuring device delivering micrometer level reproducibility with sub-micrometer resolution. Rich connectivity options and innate processing power make it a powerful feedback building block. By interconnecting multiple Libera electron beam position processors one can build a low-latency high throughput orbit feedback system without adding additional hardware. Libera electron beam position processor ...

  4. Beam processing of advanced materials

    International Nuclear Information System (INIS)

    Singh, J.; Copley, S.M.

    1993-01-01

    International Conference on Beam Processing of Advanced Materials was held at the Fall TMS/ASM Materials Week at Chicago, Illinois, November 2--5, 1992. The symposium was devoted to the recent advances in processing of materials by an energy source such as laser, electron, ion beams, etc. The symposium served as a forum on the science of beam-induced materials processing and implications of this science to practical implementation. An increased emphasis on obtaining an understanding of the fundamental mechanisms of beam-induced surface processes was a major trend observed at this years symposium. This has resulted in the increased use of advanced diagnostic techniques and modeling studies to determine the rate controlling steps in these processes. Individual papers have been processed separately for inclusion in the appropriate data bases

  5. Center for Beam Physics, 1992

    International Nuclear Information System (INIS)

    1993-06-01

    This report contains the following information on the center for beam physics: Facilities; Organizational Chart; Roster; Profiles of Staff; Affiliates; Center Publications (1991--1993); and 1992 Summary of Activities

  6. Monitor of SC beam profiles

    CERN Multimedia

    CERN PhotoLab

    1977-01-01

    A high-resolution secondary emission grid for the measurement of SC beam profiles. Modern techniques of metal-ceramic bonding, developed for micro-electronics, have been used in its construction. (See Annual Report 1977 p. 105 Fig. 12.)

  7. RIKEN RI Beam Factory project

    Energy Technology Data Exchange (ETDEWEB)

    Yano, Yasushige; Goto, Akira; Katayama, Takeshi [Institute of Physical and Chemical Research, Wako, Saitama (Japan)

    1997-03-01

    The RARF proposes `RIKEN RI Beam Factory` as a next facility-expanding project. The factory makes it the primary aim to provide RI (Radioactive Isotope) beams covering over the whole atomic-mass range with the world-highest intensity in a wide energy range up to several hundreds MeV/nucleon. These RI beams are generated by the fragmentation of high-intensity heavy-ion beams. For the efficient production heavy-ion energies will be boosted up to over 100 MeV/nucleon even for very heavy ions by a K2500-MeV superconducting ring cyclotron serving as a post accelerator of the existing K540-MeV ring cyclotron. A new type of experimental installation called `MUSES` (Multi-USe Experimental Storage rings) will be constructed as well. With MUSES, various types of unique colliding experiments will become possible. (author)

  8. Partially coherent isodiffracting pulsed beams

    Science.gov (United States)

    Koivurova, Matias; Ding, Chaoliang; Turunen, Jari; Pan, Liuzhan

    2018-02-01

    We investigate a class of isodiffracting pulsed beams, which are superpositions of transverse modes supported by spherical-mirror laser resonators. By employing modal weights that, for stationary light, produce a Gaussian Schell-model beam, we extend this standard model to pulsed beams. We first construct the two-frequency cross-spectral density function that characterizes the spatial coherence in the space-frequency domain. By assuming a power-exponential spectral profile, we then employ the generalized Wiener-Khintchine theorem for nonstationary light to derive the two-time mutual coherence function that describes the space-time coherence of the ensuing beams. The isodiffracting nature of the laser resonator modes permits all (paraxial-domain) calculations at any propagation distance to be performed analytically. Significant spatiotemporal coupling is revealed in subcycle, single-cycle, and few-cycle domains, where the partial spatial coherence also leads to reduced temporal coherence even though full spectral coherence is assumed.

  9. Beam instability Workshop - plenary sessions

    International Nuclear Information System (INIS)

    2001-01-01

    The purpose of this workshop was to provide a review of the mechanisms of limiting beam instabilities, their cures, including feedback, and beam measurement for synchrotron radiation light sources. 12 plenary sessions took place whose titles are: 1) challenging brilliance and lifetime issues with increasing currents; 2) limiting instabilities in multibunch; 3) experience from high currents in B factories; 4) longitudinal dynamics in high intensity/bunch; 5) Transverse instabilities for high intensity/bunch; 6) working group introduction from ESRF experience; 7) impedance modelling: simulations, minimization; 8) report on the broadband impedance measurements and modelling workshop; 9) feedback systems for synchrotron light sources; 10) beam instabilities diagnostics; 11) harmonic cavities: the pros and cons; and 12) experimental study of fast beam-ion instabilities at PLS. This document gathers the 12 articles that were presented during these sessions

  10. Electrostatic beam-position monitor

    CERN Multimedia

    CERN PhotoLab

    1969-01-01

    Electrostatic beam-position monitor installed in its final location (bake-out cover removed). The ISR will contain about 110 of these monitors. Their accuracy is better than 1 mm, their band width about 1 MHz.

  11. Appendix B : small beam tests.

    Science.gov (United States)

    2013-03-01

    The AASHTO LRFD Bridge Design Specifications (2007) require that confinement : reinforcement be placed around prestressing strands in the bottom bulb of pretensioned concrete : beams. Although the AASHTO specifications contain prescriptive requiremen...

  12. Center for Beam Physics, 1992

    Energy Technology Data Exchange (ETDEWEB)

    1993-06-01

    This report contains the following information on the center for beam physics: Facilities; Organizational Chart; Roster; Profiles of Staff; Affiliates; Center Publications (1991--1993); and 1992 Summary of Activities.

  13. Matter-Wave Tractor Beams

    DEFF Research Database (Denmark)

    Gorlach, Alexey A.; Gorlach, Maxim A.; Lavrinenko, Andrei

    2017-01-01

    Optical and acoustic tractor beams are currently the focus of intense research due to their counterintuitive property of exerting a pulling force on small scattering objects. In this Letter we propose a matter-wave tractor beam and utilize the de Broglie waves of nonrelativistic matter particles...... in analogy to "classical" tractor beams. We reveal the presence of the quantum-mechanical pulling force for the variety of quantum mechanical potentials observing the resonant enhancement of the pulling effect under the conditions of the suppressed scattering known as the Ramsauer-Townsend effect. We also...... are compared, and the matter-wave pulling force is found to have exclusive properties of dragging slow particles in short-range potentials. We envisage that the use of tractor beams could lead to the unprecedented precision in manipulation with atomic-scale quantum objects....

  14. A recycling molecular beam reactor

    International Nuclear Information System (INIS)

    Prada-Silva, G.; Haller, G.L.; Fenn, J.B.

    1974-01-01

    In a Recycling Molecular Beam Reactor, RMBR, a beam of reactant gas molecules is formed from a supersonic free jet. After collision with a target the molecules pass through the vacuum pumps and are returned to the nozzle source. Continuous recycling permits the integration of very small reaction probabilities into measurable conversions which can be analyzed by gas chromatography. Some preliminary experiments have been carried out on the isomerization of cyclopropane

  15. Fractional viscoelastic beam under torsion

    Science.gov (United States)

    Colinas-Armijo, N.; Cutrona, S.; Di Paola, M.; Pirrotta, A.

    2017-07-01

    This paper introduces a study on twisted viscoelastic beams, having considered fractional calculus to capture the viscoelastic behaviour. Further another novelty of this paper is extending a recent numerical approach, labelled line elementless method (LEM), to viscoelastic beams. The latter does not require any discretization neither in the domain nor in the boundary. Some numerical applications have been reported to demonstrate the efficiency and accuracy of the method.

  16. Stability diagram of colliding beams

    CERN Document Server

    Buffat, X; Mounet, N; Pieloni, T

    2014-01-01

    The effect of the beam-beam interactions on the stability of impedance mode is discussed. The detuning is evaluated by the means of single particle tracking in arbitrarily complex collision configurations, including lattice non-linearities, and used to numerically evaluate the dispersion integral. This approach also allows the effect of non-Gaussian distributions to be considered. Distributions modified by the action of external noise are discussed.

  17. FEL options for power beaming

    International Nuclear Information System (INIS)

    Kim, K.J.; Zholents, A.A.; Zolotorev, M.S.; Vinokurov, N.A.

    1997-10-01

    The demand for the output power of communication satellites has been increasing exponentially. The satellite power is generated from solar panels which collect the sunlight and convert it to electrical power. The power per satellite is limited due to the limit in the practical size of the solar panel. One way to meet the power demand is to employ multiple satellites (up to 10) per the internationally agreed-upon ''slot'' in the geosynchronous earth orbit (GEO). However, this approach is very expensive due to the high cost of sending a satellite into a GEO orbit. An alternative approach is power beaming, i.e., to illuminate the solar panels with high power, highly-directed laser beams from earth. The power beaming generates more power per satellite for the same area of the solar panel. The minimum optical beam power, interesting for power beaming application, is P L = 200kW. The wavelength is chosen to be λ 0.84 microm, so that it is within one of the transmission windows of the air, and at the same time near the peak of the photo-voltaic conversion efficiency of Si, which is the commonly used material for the solar panels. Free electron lasers (FELs) are well suited for the power beaming application because they can provide high power with coherent wavefront, but without high energy density in media. In this article the authors discuss some principal issues, such as the choice of accelerator and electron gun, the choice of beam parameters, radiation hazards, technological availability, and overall efficiency and reliability of the installation. They also attempt to highlight the compromise between the cost of the primary installation, the operation cost, and the choice of technology, and its maturity. They then present several schemes for the accelerator-FEL systems based on RF accelerators. The initial electron beam accelerator up to the energy of a few MeV is more or less common for all these schemes

  18. Beam Trajectory Correction for SNS

    CERN Document Server

    Chu, Chungming

    2005-01-01

    Automated beam trajectory correction with dipole correctors is developed and tested during the Spallation Neutron Source warm linac commissioning periods. The application is based on the XAL Java framework with newly developed optimization tools. Also, dipole corrector polarities and strengths, and beam position monitor (BPM) polarities were checked by an orbit difference program. The on-line model is used in both the trajectory correction and the orbit difference applications. Experimental data for both applications will be presented.

  19. Beam Instabilities in Hadron Synchrotrons

    CERN Document Server

    Métral, E; Bartosik, H; Biancacci, N; Buffat, X; Esteban Muller, J F; Herr, W; Iadarola, G; Lasheen, A; Li, K; Oeftiger, A; Pieloni, T; Quartullo, D; Rumolo, G; Salvant, B; Schenk, M; Shaposhnikova, E; Tambasco, C; Timko, H; Zannini, C; Burov, A; Banfi, D; Barranco, J; Mounet, N; Boine-Frankenheim, O; Niedermayer, U; Kornilov, V; White, S

    2016-01-01

    Beam instabilities cover a wide range of effects in particle accelerators and they have been the subjects of intense research for several decades. As the machines performance was pushed new mechanisms were revealed and nowadays the challenge consists in studying the interplays between all these intricate phenomena, as it is very often not possible to treat the different effects separately. The aim of this paper is to review the main mechanisms, discussing in particular the recent developments of beam instability theories and simulations.

  20. Combined phenomena of beam-beam and beam-electron cloud interactionsin circular e^{+}e^{-} colliders

    Directory of Open Access Journals (Sweden)

    Kazuhito Ohmi

    2002-10-01

    Full Text Available An electron cloud causes various effects in high intensity positron storage rings. The positron beam and the electron cloud can be considered a typical two-stream system with a certain plasma frequency. Beam-beam interaction is another important effect for high luminosity circular colliders. Colliding two beams can be considered as a two-stream system with another plasma frequency. We study the combined phenomena of the beam-electron cloud and beam-beam interactions from a viewpoint of two complex two-stream effects with two plasma frequencies.

  1. Flat beams in the SLC

    International Nuclear Information System (INIS)

    Adolphsen, C.; Barklow, T.; Burke, D.; Decker, F.J.; Emma, P.; Hildreth, M.; Himel, T.; Krejcik, P.; Limberg, T.; Minty, M.

    1993-01-01

    The Stanford Linear Collider was designed to operate with round beams; horizontal and vertical emittance made equal in the damping rings. The main motivation was to facilitate the optical matching through beam lines with strong coupling elements like the solenoid spin rotator magnets and the SLC arcs. Tests in 1992 showed that open-quote flat close-quote beams with a vertical to horizontal emittance ratio of around 1/10 can be successfully delivered to the end of the linac. Techniques developed to measure and control the coupling of the SLC arcs allow These beams to be transported to the Interaction Point (IP). Before flat beams could be used for collisions with polarized electrons, a new method of rotating the electron spin orientation with vertical arc orbit bumps had to be developed. Early in the 1993 run, the SLC was switched to open-quote flat close-quote beam operation. Within a short time the peak luminosity of the previous running cycle was reached and then surpassed. The average daily luminosity is now a factor of about two higher than the best achieved last year. In the following the authors present an overview of the problems encountered and their solutions for different parts of the SLC

  2. The ELENA Beam Diagnostics Systems

    CERN Document Server

    Tranquille, G

    2013-01-01

    The Extra Low ENergy Antiproton ring (ELENA) to be built at CERN is aimed at substantially increasing the number of antiprotons to the low energy antiproton physics community. It will be a small machine which will decelerate low intensity beams (<4x107) from 5.3 MeV to 100 keV and will be equipped with an electron cooler to avoid beam losses during the deceleration and to significantly reduce beam phase space at extraction. To measure the beam parameters from the extraction point of the Antiproton Decelerator (AD), through the ELENA ring and all the way to the experiments, many systems will be needed to ensure that the desired beam characteristics are obtained. Particular attention needs to be paid to the performance of the electron cooler which depends on reliable instrumentation in order to efficiently cool the antiprotons. This contribution will present the different monitors that have been proposed to measure the various beam parameters as well as some of the developments going on to further improve th...

  3. Two kinds of Airy-related beams

    International Nuclear Information System (INIS)

    Xu, Yiqing; Zhou, Guoquan; Zhang, Lijun; Ru, Guoyun

    2015-01-01

    Two kinds of Airy-related beams are introduced in this manuscript. The normalized intensity distribution in the x-direction of the two kinds of Airy-related beams is close to that of the Gaussian beam. The normalized intensity distribution in the y-direction of the two kinds of Airy-related beams is close to that of the second-order and the third-order elegant Hermite–Gaussian beams, respectively. Analytical expressions of the two kinds of Airy-related beams passing through an ABCD paraxial optical system are derived. The beam propagation factors for the two kinds of Airy-related beams are 1.933 and 2.125, respectively. Analytical expressions of the beam half widths and the kurtosis parameters of the two kinds of Airy-related beams passing through an ABCD paraxial optical system are also presented. As a numerical example, the propagation properties of the two kinds of Airy-related beams are demonstrated in free space. Moreover, the comparison between the two kinds of Airy-related beams and their corresponding elegant Hermite–Gaussian beams along the two transverse directions are performed in detail. Upon propagation, the former kind of Airy-related beam will evolve from the central bright beam into the dark hollow beam. Contrarily, the latter kind of Airy-related beam will evolve from the dark hollow beam into the central bright beam. These two kinds of Airy-related beams can be used to describe specially distributed beams. (paper)

  4. Damage Detection In Laboratory Concrete Beams

    DEFF Research Database (Denmark)

    Brincker, Rune; Andersen, Palle; Kirkegaard, Poul Henning

    1995-01-01

    : a beam with a typical reinforcement ratio, and a beam with a small reinforcement ratio. The modal properties of the beams were found exciting the beams by a series of pulses and identifying the properties using ARMA and ARMAX models. It was found, that extremely small damages could be detected...

  5. Damage Detection in Laboratory Concrete Beams

    DEFF Research Database (Denmark)

    Brincker, Rune; Andersen, P.; Kirkegaard, Poul Henning

    : a beam with a typical reinforcement ratio, and a beam with a small reinforcement ratio. The modal properties of the beams were found exciting the beams by a series of pulses and identifying the properties using ARMA and ARMAX models. It was found, that extremely small damages could be detected...

  6. KTeV beam systems design report

    Energy Technology Data Exchange (ETDEWEB)

    Bocean, V.; Childress, S.; Coleman, R. [and others

    1997-09-01

    The primary and secondary beams for the KTeV experiments E799-II and E832 are discussed. The specifications are presented and justified. The technical details of the implementation of the primary beam transport and stability are detailed. The target, beam dump, and radiation safety issues are discussed. The details of the collimation system for the pair of secondary beams are presented.

  7. Ion beam notcher using a laser

    Energy Technology Data Exchange (ETDEWEB)

    Ray Tomlin

    2001-07-20

    The FNAL LINAC will soon be asked to produce beam at 7.5 Hz. FNAL LINAC extraction involves sweeping the H-minus beam over a Lambertson magnet. The higher repetition rates are expected to activate the Lambertson magnet. A pulsed laser has been installed to make a notch in the beam so that beam will not sweep over the magnet.

  8. Photon collider beam simulation with CAIN

    Indian Academy of Sciences (India)

    the laser pulse and the beam–beam interaction, is presented in figure 1. Energy flow obtained from the simulation was scaled to the average beam power. After the. Compton scattering, most of the incident electron beam power is transfered to the photon beam. However, the high-energy photons are very well-collimated ...

  9. Beam instrumentation in a multidisciplinary accelerator facility

    NARCIS (Netherlands)

    Schippers, J.M.; Boon, S.N.; Dermois, O.C.; Kiewiet, H.H.

    Some recently developed beam diagnostic devices for the beam lines of the AGOR cyclotron are reviewed. The range of applications is from low background nuclear physics experiments at "zero degree" to radiation therapy with proton beams. In particular a method to improve beam quality and the

  10. Luminosity Loss due to Beam Distortion and the Beam-Beam Instability

    CERN Document Server

    Wu, Juhao; Raubenheimer, Tor O; Seryi, Andrei; Sramek, Christopher K

    2005-01-01

    In a linear collider, sources of emittance dilution such as transverse wakefields or dispersive errors will couple the vertical phase space to the longitudinal position within the beam (the so-called ‘banana effect'). When the Intersection Point (IP) disruption parameter is large, these beam distortions will be amplified by a single bunch kink instability which will lead to luminosity loss. We study this phenomena both analytically using linear theory and via numerical simulation. In particular, we examine the dependence of the luminosity loss on the wavelength of the beam distortions and the disruption parameter. This analysis may prove useful when optimizing the vertical disruption parameter for luminosity operation with given beam distortions.

  11. Detection of Equipment Faults Before Beam Loss

    CERN Document Server

    Galambos, J.

    2016-01-01

    High-power hadron accelerators have strict limits on fractional beam loss. In principle, once a high-quality beam is set up in an acceptable state, beam loss should remain steady. However, in practice, there are many trips in operational machines, owing to excessive beam loss. This paper deals with monitoring equipment health to identify precursor signals that indicate an issue with equipment that will lead to unacceptable beam loss. To this end, a variety of equipment and beam signal measurements are described. In particular, several operational examples from the Spallation Neutron Source (SNS) of deteriorating equipment functionality leading to beam loss are reported.

  12. MTN magnet for the SPS extracted beam.

    CERN Multimedia

    CERN PhotoLab

    1976-01-01

    This type of dipole magnet was used in the extracted beam lines of the North Area. It shows an opening for three different proton beam lines: a primary extracted proton beam, split by an upstream magnetic beam splitter (see photo 7612017) into three separated beams passes through different parts of its aperture: right, left up, left down. These magnets were designed to be concrete-insulated for radiation resistance. F. Streun stands on the right.

  13. Proton beam monitor chamber calibration

    International Nuclear Information System (INIS)

    Gomà, C; Meer, D; Safai, S; Lorentini, S

    2014-01-01

    The first goal of this paper is to clarify the reference conditions for the reference dosimetry of clinical proton beams. A clear distinction is made between proton beam delivery systems which should be calibrated with a spread-out Bragg peak field and those that should be calibrated with a (pseudo-)monoenergetic proton beam. For the latter, this paper also compares two independent dosimetry techniques to calibrate the beam monitor chambers: absolute dosimetry (of the number of protons exiting the nozzle) with a Faraday cup and reference dosimetry (i.e. determination of the absorbed dose to water under IAEA TRS-398 reference conditions) with an ionization chamber. To compare the two techniques, Monte Carlo simulations were performed to convert dose-to-water to proton fluence. A good agreement was found between the Faraday cup technique and the reference dosimetry with a plane-parallel ionization chamber. The differences—of the order of 3%—were found to be within the uncertainty of the comparison. For cylindrical ionization chambers, however, the agreement was only possible when positioning the effective point of measurement of the chamber at the reference measurement depth—i.e. not complying with IAEA TRS-398 recommendations. In conclusion, for cylindrical ionization chambers, IAEA TRS-398 reference conditions for monoenergetic proton beams led to a systematic error in the determination of the absorbed dose to water, especially relevant for low-energy proton beams. To overcome this problem, the effective point of measurement of cylindrical ionization chambers should be taken into account when positioning the reference point of the chamber. Within the current IAEA TRS-398 recommendations, it seems advisable to use plane-parallel ionization chambers—rather than cylindrical chambers—for the reference dosimetry of pseudo-monoenergetic proton beams. (paper)

  14. Transverse mode coupling instability of colliding beams

    Directory of Open Access Journals (Sweden)

    S. White

    2014-04-01

    Full Text Available In high brightness circular colliders, coherent and incoherent beam dynamics are dominated by beam-beam interactions. It is generally assumed that the incoherent tune spread introduced by the beam-beam interactions is sufficiently large to cure any instabilities originating from impedance. However, as the two counterrotating beams interact they can give rise to coherent dipole modes and therefore modify the coherent beam dynamics and stability conditions. In this case, coherent beam-beam effects and impedance cannot be treated independently and their interplay should be taken into account in any realistic attempt to study the beam stability of colliding beams. Due to the complexity of these physics processes, numerical simulations become an important tool for the analysis of this system. Two approaches are proposed in this paper: a fully self-consistent multiparticle tracking including particle-in-cell Poisson solver for the beam-beam interactions and a linearized model taking into account finite bunch length effects. To ensure the validity of the results a detailed benchmarking of these models was performed. It will be shown that under certain conditions coherent beam-beam dipole modes can couple with higher order headtail modes and lead to strong instabilities with characteristics similar to the classical transverse mode coupling instability originating from impedance alone. Possible cures for this instability are explored both for single bunch and multibunch interactions. Simulation results and experimental evidences of the existence of this instability at the LHC will be presented for the specific case of offset collisions.

  15. Finite element modelling of composite castellated beam

    Directory of Open Access Journals (Sweden)

    Frans Richard

    2017-01-01

    Full Text Available Nowadays, castellated beam becomes popular in building structural as beam members. This is due to several advantages of castellated beam such as increased depth without any additional mass, passing the underfloor service ducts without changing of story elevation. However, the presence of holes can develop various local effects such as local buckling, lateral torsional buckling caused by compression force at the flange section of the steel beam. Many studies have investigated the failure mechanism of castellated beam and one technique which can prevent the beam fall into local failure is the use of reinforced concrete slab as lateral support on castellated beam, so called composite castellated beam. Besides of preventing the local failure of castellated beam, the concrete slab can increase the plasticity moment of the composite castellated beam section which can deliver into increasing the ultimate load of the beam. The aim of this numerical studies of composite castellated beam on certain loading condition (monotonic quasi-static loading. ABAQUS was used for finite element modelling purpose and compared with the experimental test for checking the reliability of the model. The result shows that the ultimate load of the composite castellated beam reached 6.24 times than the ultimate load of the solid I beam and 1.2 times compared the composite beam.

  16. Developments in non-destructive beam diagnostics

    International Nuclear Information System (INIS)

    Fraser, J.S.

    1981-01-01

    With the large average beam currents being achieved in accelerators and storage rings, there is an increasing need for non-destructive beam diagnostic devices. For continuous beams, position monitors of the capacitive pick-up type are replaced by resonant devices that respond to the transverse displacement of the beam centroid. Bunch length monitors of the SLAC type using resonant cavities operating in the TM 010 mode can be used for continuous beams. The more detailed information derivable from beam profile scanners requires development of improved non-destructive devices. Profile monitors which scan the visible light produced by high current beams may be more reliable than ones using the residual ionization if the light intensity from gas molecules following nonionizing collisions with beam particles gives a measure of the beam current density independent of the local electron density. The intense Balmer series lines from neutral hydrogen beams have been used successfully to measure beam profiles. At CRNL and at LASL, beam light profile monitors are being developed for high average current accelerators. Three or more projections will be recorded to allow tomographic reconstruction of the two-dimensional beam current density. Light detection is either by intensified Reticons or ISIT vidicons. The use of three or more beam light monitors on a beam transport line will also permit estimates of the transverse emittance to be made through the reconstruction technique

  17. Airyprime beams and their propagation characteristics

    International Nuclear Information System (INIS)

    Zhou, Guoquan; Chen, Ruipin; Ru, Guoyun

    2014-01-01

    A type of Airyprime beam is introduced in this document. An analytical expression of Airyprime beams passing through a separable ABCD paraxial optical system is derived. The beam propagation factor of the Airyprime beam is proved to be 3.676. An analytical expression of the kurtosis parameter of an Airyprime beam passing through a separable ABCD paraxial optical system is also presented. The kurtosis parameter of the Airyprime beam passing through a separable ABCD paraxial optical system depends on the two ratios B/(Az rx ) and B/(Az ry ). As a numerical example, the propagation characteristics of an Airyprime beam is demonstrated in free space. In the source plane, the Airyprime beam has nine lobes, one of which is the central dominant lobe. In the far field, the Airyprime beam becomes a dark-hollow beam with four uniform lobes. The evolvement of an Airyprime beam propagating in free space is well exhibited. Upon propagation, the intensity distribution of the Airyprime beam becomes flatter and the kurtosis parameter decreases from the maximum value 2.973 to a saturated value 1.302. The Airyprime beam is also compared with the second-order elegant Hermite–Gaussian beam. The novel propagation characteristics of Airyprime beams denote that they could have potential application prospects such as optical trapping. (letter)

  18. Hydrogen beam stopping and beam emission data for LHD

    Energy Technology Data Exchange (ETDEWEB)

    Summers, H.P.; Anderson, H. [University of Strathclyde, Glasgow (United Kingdom); Kato, T.; Murakami, S. [National Inst. for Fusion Science, Toki, Gifu (Japan)

    1999-11-01

    A set of data are presented for estimating neutral hydrogen beam stopping and Balmer alpha beam emission for the fast neutral beams from the H{sup -} source at the Large Helical Device. The data are presented as economised look-up tables and are suitable for plasmas with arbitrary mixtures of light impurity nuclei up to neon, with impurity species Ar{sup 18+} and Fe{sup 26+} also included. The data stem from very many level collisional-radiative modelling using the most up-to-date fundamental ion and electron impact cross-section information. Fortran routines are available for accessing the computer archived data files and assembling the composite coefficients for mixed impurity plasmas. (author)

  19. Beam based measurement of beam position monitor electrode gains

    Directory of Open Access Journals (Sweden)

    D. L. Rubin

    2010-09-01

    Full Text Available Low emittance tuning at the Cornell Electron Storage Ring (CESR test accelerator depends on precision measurement of vertical dispersion and transverse coupling. The CESR beam position monitors (BPMs consist of four button electrodes, instrumented with electronics that allow acquisition of turn-by-turn data. The response to the beam will vary among the four electrodes due to differences in electronic gain and/or misalignment. This variation in the response of the BPM electrodes will couple real horizontal offset to apparent vertical position, and introduce spurious measurements of coupling and vertical dispersion. To alleviate this systematic effect, a beam based technique to measure the relative response of the four electrodes has been developed. With typical CESR parameters, simulations show that turn-by-turn BPM data can be used to determine electrode gains to within ∼0.1%.

  20. Comparison of beam deposition for three neutral beam injection codes

    International Nuclear Information System (INIS)

    Wieland, R.M.; Houlberg, W.A.; Mense, A.T.

    1979-03-01

    The three neutral beam injection codes BEAM (Houlberg, ORNL), HOFR (Howe, ORNL), and FREYA (Post, PPPL) are compared with respect to the calculation of the fast ion deposition profile H(r). Only plasmas of circular cross section are considered, with injection confined to the mid-plane of the torus. The approximations inherent in each code are pointed out, and a series of comparisons varying several parameters (beam energy and radius, machine size, and injection angle) shows excellent agreement among all the codes. A cost comparison (execution time and memory requirements) is made which points out the relative merits of each code within the context of incorporation into a plasma transport simulation code

  1. Laguerre-Gauss beams versus Bessel beams showdown: peer comparison.

    Science.gov (United States)

    Mendoza-Hernández, Job; Arroyo-Carrasco, Maximino Luis; Iturbe-Castillo, Marcelo David; Chávez-Cerda, Sabino

    2015-08-15

    We present for the first time a comparison under similar circumstances between Laguerre-Gauss beams (LGBs) and Bessel beams (BB), and show that the former can be a better option for many applications in which BBs are currently used. By solving the Laguerre-Gauss differential equation in the asymptotic limit of a large radial index, we find the parameters to perform a peer comparison, showing that LGBs can propagate quasi-nondiffracting beams within the same region of space where the corresponding BBs do. We also demonstrate that LGBs, which have the property of self-healing, are more robust in the sense that they can propagate further than BBs under similar initial conditions.

  2. Applications of electron lenses: scraping of high-power beams, beam-beam compensation, and nonlinear optics

    Energy Technology Data Exchange (ETDEWEB)

    Stancari, Giulio

    2014-09-11

    Electron lenses are pulsed, magnetically confined electron beams whose current-density profile is shaped to obtain the desired effect on the circulating beam. Electron lenses were used in the Fermilab Tevatron collider for bunch-by-bunch compensation of long-range beam-beam tune shifts, for removal of uncaptured particles in the abort gap, for preliminary experiments on head-on beam-beam compensation, and for the demonstration of halo scraping with hollow electron beams. Electron lenses for beam-beam compensation are being commissioned in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). Hollow electron beam collimation and halo control were studied as an option to complement the collimation system for the upgrades of the Large Hadron Collider (LHC) at CERN; a conceptual design was recently completed. Because of their electric charge and the absence of materials close to the proton beam, electron lenses may also provide an alternative to wires for long-range beam-beam compensation in LHC luminosity upgrade scenarios with small crossing angles. At Fermilab, we are planning to install an electron lens in the Integrable Optics Test Accelerator (IOTA, a 40-m ring for 150-MeV electrons) as one of the proof-of-principle implementations of nonlinear integrable optics to achieve large tune spreads and more stable beams without loss of dynamic aperture.

  3. ITER Neutral Beam Injection System

    International Nuclear Information System (INIS)

    Ohara, Yoshihiro; Tanaka, Shigeru; Akiba, Masato

    1991-03-01

    A Japanese design proposal of the ITER Neutral Beam Injection System (NBS) which is consistent with the ITER common design requirements is described. The injection system is required to deliver a neutral deuterium beam of 75MW at 1.3MeV to the reactor plasma and utilized not only for plasma heating but also for current drive and current profile control. The injection system is composed of 9 modules, each of which is designed so as to inject a 1.3MeV, 10MW neutral beam. The most important point in the design is that the injection system is based on the utilization of a cesium-seeded volume negative ion source which can produce an intense negative ion beam with high current density at a low source operating pressure. The design value of the source is based on the experimental values achieved at JAERI. The utilization of the cesium-seeded volume source is essential to the design of an efficient and compact neutral beam injection system which satisfies the ITER common design requirements. The critical components to realize this design are the 1.3MeV, 17A electrostatic accelerator and the high voltage DC acceleration power supply, whose performances must be demonstrated prior to the construction of ITER NBI system. (author)

  4. Active beam spectroscopy for ITER

    International Nuclear Information System (INIS)

    Von Hellermann, M.; Giroud, C.; Jaspers, R.; Hawkes, N.C.; Mullane, M.O.; Zastrow, K.D.; Krasilnikov, A.; Tugarinov, S.; Lotte, P.; Malaquias, A.; Rachlew, E.

    2003-01-01

    The latest status of 'Active Beam' related spectroscopy aspects as part of the ITER diagnostic scenario is presented. A key issue of the proposed scheme is based on the concept that in order to achieve the ultimate goal of global data consistency, all particles involved, that is, intrinsic and seeded impurity ions as well as helium ash ions and bulk plasma ions and also the plasma background data (e.g. magnetic and electric fields, electron density and temperature profiles) need to be addressed. A further sensible step in this direction is the decision of exploiting both a dedicated low-energy, low-power diagnostic beam (DNB, 2.2 MW 100 keV/amu) as well as the high-power, high-energy heating beams (HNB, 17 MW 500 keV/amu) for maximum diagnostic information. The authors report some new aspects referring to the use of DNB for motional Stark effect (MSE) where the main idea is to treat both beams (HNB and DNB) as potential diagnostic tools with complementary roles. The equatorial ports for the DNB promise excellent spatial resolution, however, the angles are less favourable for a polarimetric MSE exploitation. HNB can be used as probe beam for diagnosing slowing-down fusion alpha with a birth energy of 3,5 MeV

  5. A clustered H2 beam

    International Nuclear Information System (INIS)

    Marcri, M.

    1984-01-01

    This chapter discusses the construction of a clustered H2 beam to obtain - pp interactions using the p beam produced in A.A. and stored via P.S. in ring 2 of ISR in order to perform an experimental study of charmonium states (experiment R 704 at the CERN ISR). Topics covered include the choice of the nozzle, the H2 injection circuit, the pumping system, measurement and controls, and actual status. A luminosity of 10 31 cm -2 sec -1 can be achieved using a circulating beam of 3x10 11- p and a target of H2 1.75x10 -10 g/cm 2 thick. The use of converging-diverging nozzles is effective for the production of very intense beams of clusters of H2 molecules. Differential pumping stages are needed to keep the pressure in the ISR ring down to acceptable values for the operation of the machine (pumping system of the ISR, beam lifetime, signal to noise ratio)

  6. RIKEN RI Beam Factory project

    International Nuclear Information System (INIS)

    Yano, Y.; Katayama, T.

    1996-01-01

    The RARF has a heavy-ion accelerator complex consisting of a K540-MeV ring cyclotron as a booster accelerator and two different types of injectors. The facility provides not only nuclear physicists but also researchers of atomic physics, nuclear chemistry, material science, radiobiology and others with various kinds of heavy-ion beams of an energy range of 10 MeV/nucleon to 100 MeV/nucleon. One of remarkable features of this facility is capability of supplying RI (radioactive isotope) beams with the world-highest level of intensities. In these several years the RI beam has opened up a quite new and fascinating heavy-ion science. In order to further promote this new science, we propose open-quote open-quote RIKEN RI Beam Factory close-quote close-quote as a future project of the RARF: The existing facility will be expanded into the open-quote open-quote Factory close-quote close-quote where high-intensity RI beams of the whole mass range will become available in a wide energy range up to several hundred MeV/nucleon. The concept of this new proposal as well as currently-running upgrade programs relevant to the project will be presented. copyright 1996 American Institute of Physics

  7. Low voltage electron beam accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Ochi, Masafumi [Iwasaki Electric Co., Ltd., Tokyo (Japan)

    2003-02-01

    Widely used electron accelerators in industries are the electron beams with acceleration voltage at 300 kV or less. The typical examples are shown on manufactures in Japan, equipment configuration, operation, determination of process parameters, and basic maintenance requirement of the electron beam processors. New electron beam processors with acceleration voltage around 100 kV were introduced maintaining the relatively high dose speed capability of around 10,000 kGy x mpm at production by ESI (Energy Science Inc. USA, Iwasaki Electric Group). The application field like printing and coating for packaging requires treating thickness of 30 micron or less. It does not require high voltage over 110 kV. Also recently developed is a miniature bulb type electron beam tube with energy less than 60 kV. The new application area for this new electron beam tube is being searched. The drive force of this technology to spread in the industries would be further development of new application, process and market as well as the price reduction of the equipment, upon which further acknowledgement and acceptance of the technology to societies and industries would entirely depend. (Y. Tanaka)

  8. High current DC ion beams

    International Nuclear Information System (INIS)

    Shubaly, M.R.; de Jong, M.S.

    1983-01-01

    Development of high-current cw accelerators such as ZEBRA and FMIT, use of high current dc ion beams in industry for sputtering and material treatment, and scientific applications such as heavy-ion fusion and plasma physics diagnostics have provided the impetus for ion source development programs at many laboratories. At Chalk River, development of efficient plasma generators and reliable extraction columns to provide high quality beams of hydrogen, nitrogen, argon and xenon is underway. DC beams of up to 850 mA (limited by available power supplies) of hydrogen, 200 mA of nitrogen, 155 mA of argon and 100 mA of xenon have been produced with good reliability. DuoPIGatrons, with and without magnetic cusps, are used to generate a high density, reasonably quiescent plasma. Multi-aperture accel-decel columns are used for extraction with shaped apertures and beamlet steering to improve beam quality. This paper describes the performance of these sources and identifies some of the remaining problems. Guidelines for extraction column design, and experience with transporting high current beams are also presented

  9. Free-electron laser beam

    International Nuclear Information System (INIS)

    Minehara, Eisuke

    2003-01-01

    The principle and history of free-electron laser (FEL), first evidenced in 1977, the relationship between FEL wavelength and output power, the high-power FEL driven by the superconducting linac, the X-ray FEL by the linac, and the medical use are described. FEL is the vacuum oscillator tube and essentially composed from the high-energy linac, undulator and light-resonator. It utilizes free electrons in the vacuum to generate the beam with wavelength ranging from microwave to gamma ray. The first high-power FEL developed in Japanese Atomic Energy Research Institute (JAERI) is based on the development of superconducting linac for oscillating the highest power beam. In the medical field, applications to excise brain tumors (in US) and to reconstruct experimentally blood vessels in the pig heart (in Gunma University) by lasing and laser coagulator are in progress with examinations to remove intra-vascular cholesterol mass by irradiation of 5.7μm FEL beam. Cancer cells are considered diagnosed by FEL beam of far-infrared-THz range. The FEL beam CT is expected to have a wide variety of application without the radiation exposure and its resolution is equal or superior to that of usual imaging techniques. (N.I.)

  10. The ATLAS beam conditions monitor

    CERN Document Server

    Mikuz, M; Dolenc, I; Kagan, H; Kramberger, G; Frais-Kölbl, H; Gorisek, A; Griesmayer, E; Mandic, I; Pernegger, H; Trischuk, W; Weilhammer, P; Zavrtanik, M

    2006-01-01

    The ATLAS beam conditions monitor is being developed as a stand-alone device allowing to separate LHC collisions from background events induced either on beam gas or by beam accidents, for example scraping at the collimators upstream the spectrometer. This separation can be achieved by timing coincidences between two stations placed symmetric around the interaction point. The 25 ns repetition of collisions poses very stringent requirements on the timing resolution. The optimum separation between collision and background events is just 12.5 ns implying a distance of 3.8 m between the two stations. 3 ns wide pulses are required with 1 ns rise time and baseline restoration in 10 ns. Combined with the radiation field of 10/sup 15/ cm/sup -2/ in 10 years of LHC operation only diamond detectors are considered suitable for this task. pCVD diamond pad detectors of 1 cm/sup 2/ and around 500 mum thickness were assembled with a two-stage RF current amplifier and tested in proton beam at MGH, Boston and SPS pion beam at...

  11. METHOD OF ELECTRON BEAM PROCESSING

    DEFF Research Database (Denmark)

    2003-01-01

    As a rule, electron beam welding takes place in a vacuum. However, this means that the workpieces in question have to be placed in a vacuum chamber and have to be removed therefrom after welding. This is time−consuming and a serious limitation of a process the greatest advantage of which is the o......As a rule, electron beam welding takes place in a vacuum. However, this means that the workpieces in question have to be placed in a vacuum chamber and have to be removed therefrom after welding. This is time−consuming and a serious limitation of a process the greatest advantage of which...... is the option of welding workpieces of large thicknesses. Therefore the idea is to guide the electron beam (2) to the workpiece via a hollow wire, said wire thereby acting as a prolongation of the vacuum chamber (4) down to workpiece. Thus, a workpiece need not be placed inside the vacuum chamber, thereby...... exploiting the potential of electron beam processing to a greater degree than previously possible, for example by means of electron beam welding...

  12. Propagation of light ion beam

    International Nuclear Information System (INIS)

    Okada, Toshio; Murakami, Hiroyuki; Niu, Keishiro.

    1983-01-01

    A method of rotating ion layer is proposed as a possible driver for inertial confinement fusion for the purpose of obtaining more stable ion beam against various micro- and macroinstabilities. The analysis was carried out within the frameworks of Vlasov and fluid models. A rotating ion layer propagating in the Z-direction is considered. The beam is described by a distribution function which satisfies the Vlasov equation. The equilibrium and microstability were studied. The filamentation instability is suppressed by a magnetic field due to the rotation of ion beam. To study the properties of the equilibrium state from the macroscopic standpoint, the equation of continuity of ion beam, the equation of motion and the Maxwell equations are considered. It is shown that the macroinstability is stabilized by the magnetic field in the Z-direction. It was found that the most dangerous instability for the problem of the propagation of ion beam was able to be atabilized by using a rotating ion layer. (Kato, T.)

  13. Sciences with radioactive nuclear beams

    International Nuclear Information System (INIS)

    Kawase, Yoichi

    1992-01-01

    The unstable nuclei which are produced with accelerators and nuclear reactors and are far apart from the stability line have been used mainly in nuclear physics field as the object of the systematic research on atomic nucleus structure. Recently, the projects for developing the advanced research in many fields by accelerating the obtained unstable nuclei have been proposed. The unstable nucleus beam which was accelerated to high energy and controlled precisely keeps the possibility of qualitatively improve further conventional ion beam science, and it is expected as the breakthrough in the interdisciplinary basic research related to atomic energy, therefore, its recent trend in the world is explained, hoping for the new development. The stable isotopes existing naturally distribute along the N-Z straight line, and as they are apart from the natural stability line, they become unstable to beta decay, and their life becomes short exponentially. The significance of unstable nucleus beam science and its recent trend, the production of unstable nucleus beam, the interdisciplinary research using unstable nucleus beam, and the present state and future plan in Research Reactor Institute, Kyoto University are reported. (K.I.)

  14. Low voltage electron beam accelerators

    International Nuclear Information System (INIS)

    Ochi, Masafumi

    2003-01-01

    Widely used electron accelerators in industries are the electron beams with acceleration voltage at 300 kV or less. The typical examples are shown on manufactures in Japan, equipment configuration, operation, determination of process parameters, and basic maintenance requirement of the electron beam processors. New electron beam processors with acceleration voltage around 100 kV were introduced maintaining the relatively high dose speed capability of around 10,000 kGy x mpm at production by ESI (Energy Science Inc. USA, Iwasaki Electric Group). The application field like printing and coating for packaging requires treating thickness of 30 micron or less. It does not require high voltage over 110 kV. Also recently developed is a miniature bulb type electron beam tube with energy less than 60 kV. The new application area for this new electron beam tube is being searched. The drive force of this technology to spread in the industries would be further development of new application, process and market as well as the price reduction of the equipment, upon which further acknowledgement and acceptance of the technology to societies and industries would entirely depend. (Y. Tanaka)

  15. Primary beams of an electron beam ion source (EBIS)

    International Nuclear Information System (INIS)

    Lenoir-Zink, E.

    1986-06-01

    Electron guns for the ion sources of the SATURN II facility were tested and compared with models. The guns tested were a gun with 36 mm diameter cathode, 7 mm, 4 mm, 4 mm with insulated Whenelt, and 8 mm. A lanthanium hexaboride cathode is presented. For the primary ion beams, zeolite and plasma sources were realized. In DIONE, which will replace CRYEBIS as ion source in SATURNE, the density of the electron beam compressed within the maximum magnetic field can be evaluated. Results indicate a factor of 3 improvement compared with CRYEBIS. Lithium sources can be used, but gas sources do not produce significant improvements [fr

  16. Spin Depolarization due to Beam-Beam Interaction in NLC

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, Kathleen A

    2001-01-04

    Calculations of spin depolarization effects due to the beam-beam interaction are presented for several NLC designs. The depolarization comes from both classical (Bargmann-Michel-Telegdi precession) and quantum (Sokolov-Ternov spin-flip) effects. It is anticipated that some physics experiments at future colliders will require a knowledge of the polarization to better than 0.5% precision. We compare the results of CAIN simulations with the analytic estimates of Yokoya and Chen for head-on collisions. We also study the effects of transverse offsets and beamstrahlung-induced energy spread.

  17. A beam radiation monitoring and protection system for AGS secondary beams

    International Nuclear Information System (INIS)

    Levine, G.S.

    1978-01-01

    A commercially available radiation monitor using a scintillation detector was modified for charged particle beam monitoring. The device controls access to secondary beams of the AGS and limits beam intensity

  18. Characterization of the Li beam probe with a beam profile monitor on JET.

    Science.gov (United States)

    Nedzelskiy, I S; Korotkov, A; Brix, M; Morgan, P; Vince, J

    2010-10-01

    The lithium beam probe (LBP) is widely used for measurements of the electron density in the edge plasma of magnetically confined fusion experiments. The quality of LBP data strongly depends on the stability and profile shape of the beam. The main beam parameters are as follows: beam energy, beam intensity, beam profile, beam divergence, and the neutralization efficiency. For improved monitoring of the beam parameters, a beam profile monitor (BPM) from the National Electrostatics Corporation (NEC) has been installed in the Li beam line at JET. In the NEC BPM, a single grounded wire formed into a 45° segment of a helix is rotated by a motor about the axis of the helix. During each full revolution, the wire sweeps twice across the beam to give X and Y profiles. In this paper, we will describe the properties of the JET Li beam as measured with the BPM and demonstrate that it facilitates rapid optimization of the gun performance.

  19. Beam-energy and laser beam-profile monitor at the BNL LINAC

    Energy Technology Data Exchange (ETDEWEB)

    Connolly, R.; Briscoe, B.; Degen, C.; DeSanto, L.; Meng, W.; Minty, M.; Nayak, S.; Raparia, D.; Russo, T.

    2010-05-02

    We are developing a non-interceptive beam profile and energy monitor for H{sup -} beams in the high energy beam transport (HEBT) line at the Brookhaven National Lab linac. Electrons that are removed from the beam ions either by laser photodetachment or stripping by background gas are deflected into a Faraday cup. The beam profile is measured by stepping a narrow laser beam across the ion beam and measuring the electron charge vs. transverse laser position. There is a grid in front of the collector that can be biased up to 125kV. The beam energy spectrum is determined by measuring the electron charge vs. grid voltage. Beam electrons have the same velocity as the beam and so have an energy of 1/1836 of the beam protons. A 200MeV H{sup -} beam yields 109keV electrons. Energy measurements can be made with either laser-stripped or gas-stripped electrons.

  20. Transport of ion beams by magnetic fields on the beam edges

    International Nuclear Information System (INIS)

    Hooper, E.B.

    1975-01-01

    The transport of low energy ion beams (less than 10 keV) by magnetic fields on the edge of the beam is analyzed. Calculations indicate that beams with low transverse temperature can be transported. (U.S.)

  1. Electron beam solenoid reactor concept

    International Nuclear Information System (INIS)

    Bailey, V.; Benford, J.; Cooper, R.; Dakin, D.; Ecker, B.; Lopez, O.; Putman, S.; Young, T.S.T.

    1977-01-01

    The electron Beam Heated Solenoid (EBHS) reactor is a linear magnetically confined fusion device in which the bulk or all of the heating is provided by a relativistic electron beam (REB). The high efficiency and established technology of the REB generator and the ability to vary the coupling length make this heating technique compatible with several radial and axial enery loss reduction options including multiple-mirrors, electrostatic and gas end-plug techniques. This paper addresses several of the fundamental technical issues and provides a current evaluation of the concept. The enhanced confinement of the high energy plasma ions due to nonadiabatic scattering in the multiple mirror geometry indicates the possibility of reactors of the 150 to 300 meter length operating at temperatures > 10 keV. A 275 meter EBHS reactor with a plasma Q of 11.3 requiring 33 MJ of beam eneergy is presented

  2. Standardization of beam line representations

    International Nuclear Information System (INIS)

    Carey, David C.

    1999-01-01

    Standardization of beam line representations means that a single set of data can be used in many situations to represent a beam line. This set of data should be the same no matter what the program to be run or the calculation to be made. We have concerned ourselves with three types of standardization: (1) The same set of data should be usable by different programs. (2) The inclusion of other items in the data, such as calculations to be done, units to be used, or preliminary specifications, should be in a notation similar to the lattice specification. (3) A single set of data should be used to represent a given beam line, no matter what is being modified or calculated. The specifics of what is to be modified or calculated can be edited into the data as part of the calculation. These three requirements all have aspects not previously discussed in a public forum. Implementations into TRANSPORT will be discussed

  3. Polarized electron beams at SLAC

    International Nuclear Information System (INIS)

    Moffeit, K.C.

    1992-11-01

    SLAC has successfully accelerated high energy polarized electrons for the Stanford Linear Collider and fixed polarized nuclear target experiments. The polarized electron beams at SLAC use a gallium arsenide (GaAlAs for E-142) photon emission source to provide the beam of polarized electrons with polarization of approximately 28% (41% for E-142). While the beam emittance is reduced in the damping ring for SLC operation a system of bend magnets and superconducting solenoids preserve and orient the spin direction for maximum longitudinal polarization at the collision point. The electron polarization is monitored with a Compton scattering polarimeter, and was typically 22% at the e+e- collision point for the 1992 run. Improvements are discussed to increase the source polarization and to reduce the depolarization effects between the source and the collision point

  4. Sandia's Particle Beam Fusion Program

    International Nuclear Information System (INIS)

    Sweeney, M.A.

    1979-01-01

    Sandia's Particle Beam Fusion Program is investigating pulsed electron and light ion beam accelerators, with the goal of demonstrating the practical application of such drivers as igniters in inertial confinement fusion (ICF) reactors. Recent developments in the program are described. Traditionally, two requirements of ICF reactor operation have been the most difficult to satisfy in conceptual designs. Adequate standoff of critical components from damaging pellet emissions must be assured, and the shot repetition rate must be consistent with the desired reactor power level at reasonable pellet gains. Progress in power compression, beam focusing and transport, first-wall protection schemes, and net-energy-gain target design shows how these requirements can be met

  5. Standardization of beam line representations

    International Nuclear Information System (INIS)

    Carey, David C.

    1998-01-01

    Standardization of beam line representations means that a single set of data can be used in many situations to represent a beam line. This set of data should be the same no matter what the program to be run or the calculation to be made. We have concerned ourselves with three types of standardization: (1) The same set of data should be usable by different programs. (2) The inclusion of other items in the data, such as calculations to be done, units to be used, or preliminary specifications, should be in a notation similar to the lattice specification. (3) A single set of data should be used to represent a given beam line, no matter what is being modified or calculated. The specifics of what is to be modified or calculated can be edited into the data as part of the calculation. These three requirements all have aspects not previously discussed in a public forum. Implementations into TRANSPORT will be discussed

  6. 'Pipetron' beam dynamics with noise

    International Nuclear Information System (INIS)

    Shiltsev, V.D.

    1996-10-01

    Extra-large hadron collider, ''Pipetron'', at 100 TeV energy is currently under consideration. In this article we study the Pipetron transverse and longitudinal beam dynamics under influence of external noises. The major effects are growths of transverse and longitudinal emittances of the beam caused by noisy forces which vary over the revolution period or synchrotron oscillation period, respectively; and closed orbit distortions induced by slow drift of magnet positions. Based on analytical consideration of these phenomena, we estimate tolerable levels of these noises and compare them with available experimental data. Although it is concluded that transverse and, probably, longitudinal feedback systems are necessary for the emittance's preservation, and sophisticated beam-based orbit correction methods should be used at the Pipetron, we observe no unreasonable requirements which present and impenetrable barrier to the project

  7. The radioactive beam facility ALTO

    International Nuclear Information System (INIS)

    Essabaa, Saïd; Barré-Boscher, Nicole; Cheikh Mhamed, Maher; Cottereau, Evelyne; Franchoo, Serge; Ibrahim, Fadi; Lau, Christophe; Roussière, Brigitte; Saïd, Abdelhakim; Tusseau-Nenez, Sandrine; Verney, David

    2013-01-01

    Highlights: • Research at the ALTO TNA-facility. • R and D on radioactive ion sources. • R and D on the lanthanide beam production by fluorination. • Recent developments on uranium carbide targets. -- Abstract: The Transnational Access facility ALTO (TNA07-ENSAR/FP7) has been commissioned and received from the French safety authorities, the operation license. It is allowed to run at nominal intensity to produce 10 11 fissions/s in a thick uranium carbide target by photo-fission using a 10 μA, 50 MeV electron beam. In addition the recent success in operating the selective laser ion source broadens the physics program with neutron-rich nuclear beams possible at this facility installed at IPN Orsay. The facility also aims at being a test bench for the SPIRAL2 project. In that framework an ambitious R and D program on the target ion source system is being developed

  8. Edge imaging in intense beams

    Directory of Open Access Journals (Sweden)

    S. Bernal

    2002-06-01

    Full Text Available The appearance of rings of charge observed near the edge of beams from high-perveance guns is described with a simple ray tracing technique inspired by the particle-core model. We illustrate the technique, which has no analog in light optics, with examples from experiments employing solenoid focusing of an electron beam. The rings of charge result from the combined effects of external focusing and space-charge forces acting on paraxial fringe particles with relatively large initial transverse velocities. The model is independent of the physical mechanisms responsible for the fringe particles. Furthermore, the focal length for edge imaging in a uniform focusing channel is derived using a linearized trajectory equation for the motion of fringe particles. Counterintuitively, the focal length decreases as the beam current increases.

  9. A Southern African positron beam

    International Nuclear Information System (INIS)

    Britton, D.T.; Haerting, M.; Teemane, M.R.B.; Mills, S.; Nortier, F.M.; Van der Walt, T.N.

    1997-01-01

    The first stage of a state of the art positron beam, being constructed at the University of Cape Town, is currently being brought into operation. This is the first positron beam on the African continent, as well as being the first positron beam dedicated to solid and surface studies in the southern hemisphere. The project also contains a high proportion of local development, including the encapsulated 22 Na positron source developed by our collaboration. Novel features in the design include a purely magnetic in-line deflector, working in the solenoidal guiding field, to eliminate unmoderated positrons and block the direct line of sight to the source. A combined magnetic projector and single pole probe forming lens is being implemented in the second phase of construction to achieve a spot size of 10 μm without remoderation

  10. Radioactive ion beams at TRIUMF

    International Nuclear Information System (INIS)

    D'Auria, J.M.; Dombsky, M.; Buchmann, L.; Sprenger, H.; McNeely, P.; Roy, G.

    1992-01-01

    The thick target, on-line isotope separator, TISOL, located at the high intensity, 500 MeV proton cyclotron, TRIUMF, has now been upgraded to a production facility, and can produce mass separated radioisotopic beams for a wide range of elements. Two different types of ion sources, an Electron Cyclotron Resonance (ECR) system and a heated surface ion source are presently operational for alkali, alkaline, and gaseous elements. A new class of target materials, zeolites, have been developed to allow the use of beam intensities approaching 5 μA. A summary of the experimental program underway is presented along with planned future upgrades, and recent results on the properties of nuclides far from stability. The role of TISOL in future planned accelerated radioactive beams facilities is also discussed

  11. Cooled Beam Diagnostics on LEIR

    CERN Document Server

    Tranquille, G; Carli, C; Chanel, M; Prieto, V; Sautier, R; Tan, J

    2008-01-01

    Electron cooling is central in the preparation of dense bunches of lead beams for the LHC. Ion beam pulses from the LINAC3 are transformed into short highbrightness bunches using multi-turn injection, cooling and accumulation in the Low Energy Ion Ring, LEIR [1]. The cooling process must therefore be continuously monitored in order to guarantee that the lead ions have the required characteristics in terms of beam size and momentum spread. In LEIR a number of systems have been developed to perform these measurements. These include Schottky diagnostics, ionisation profile monitors and scrapers. Along with their associated acquisition and analysis software packages these instruments have proved to be invaluable for the optimisation of the electron cooler.

  12. Beam Cleaning and Collimation Systems

    CERN Document Server

    Redaelli, S

    2016-01-01

    Collimation systems in particle accelerators are designed to dispose of unavoidable losses safely and efficiently during beam operation. Different roles are required for different types of accelerator. The present state of the art in beam collimation is exemplified in high-intensity, high-energy superconducting hadron colliders, like the CERN Large Hadron Collider (LHC), where stored beam energies reach levels up to several orders of magnitude higher than the tiny energies required to quench cold magnets. Collimation systems are essential systems for the daily operation of these modern machines. In this document, the design of a multistage collimation system is reviewed, taking the LHC as an example case study. In this case, unprecedented cleaning performance has been achieved, together with a system complexity comparable to no other accelerator. Aspects related to collimator design and operational challenges of large collimation systems are also addressed.

  13. Pink-beam serial crystallography.

    Science.gov (United States)

    Meents, A; Wiedorn, M O; Srajer, V; Henning, R; Sarrou, I; Bergtholdt, J; Barthelmess, M; Reinke, P Y A; Dierksmeyer, D; Tolstikova, A; Schaible, S; Messerschmidt, M; Ogata, C M; Kissick, D J; Taft, M H; Manstein, D J; Lieske, J; Oberthuer, D; Fischetti, R F; Chapman, H N

    2017-11-03

    Serial X-ray crystallography allows macromolecular structure determination at both X-ray free electron lasers (XFELs) and, more recently, synchrotron sources. The time resolution for serial synchrotron crystallography experiments has been limited to millisecond timescales with monochromatic beams. The polychromatic, "pink", beam provides a more than two orders of magnitude increased photon flux and hence allows accessing much shorter timescales in diffraction experiments at synchrotron sources. Here we report the structure determination of two different protein samples by merging pink-beam diffraction patterns from many crystals, each collected with a single 100 ps X-ray pulse exposure per crystal using a setup optimized for very low scattering background. In contrast to experiments with monochromatic radiation, data from only 50 crystals were required to obtain complete datasets. The high quality of the diffraction data highlights the potential of this method for studying irreversible reactions at sub-microsecond timescales using high-brightness X-ray facilities.

  14. High power electron beam dumps at CEBAF

    International Nuclear Information System (INIS)

    Wiseman, M.; Sinclair, C.K.; Whitney, R.; Zarecky, M.

    1997-01-01

    The CEBAF accelerator produces a very small emittance CW electron beam of up to 200 μA average current. The resulting beam power, up to 1 MW at 5 GeV, and the very high beam power density, pose challenging problems for beam dump design. Two styles of high power dumps have been developed. The first, rated for 100+ kW, is used for beam tune-up and accelerator commissioning. The beam power is entirely contained in metal in this dump, minimizing the problems associated with radioactive water handling. Full power 1 MW dumps are used with the experimental halls. In these dumps, one-third of the beam power is directly absorbed in water. Both dump designs require the beam to be rastered when the smallest beam sizes are used. Design details for each of these dumps will be presented

  15. Limitations due to strong head-on beam-beam interactions (MD 1434)

    CERN Document Server

    Buffat, Xavier; Iadarola, Giovanni; Papadopoulou, Parthena Stefania; Papaphilippou, Yannis; Pellegrini, Dario; Pojer, Mirko; Crockford, Guy; Salvachua Ferrando, Belen Maria; Trad, Georges; Barranco Garcia, Javier; Pieloni, Tatiana; Tambasco, Claudia; CERN. Geneva. ATS Department

    2017-01-01

    The results of an experiment aiming at probing the limitations due to strong head on beam-beam interactions are reported. It is shown that the loss rates significantly increase when moving the working point up and down the diagonal, possibly due to effects of the 10th and/or 14th order resonances. Those limitations are tighter for bunches with larger beam-beam parameters, a maximum total beam-beam tune shift just below 0.02 could be reached.

  16. On extrapolation blowups in the $L_p$ scale

    Czech Academy of Sciences Publication Activity Database

    Capone, C.; Fiorenza, A.; Krbec, Miroslav

    2006-01-01

    Roč. 9, č. 4 (2006), s. 1-15 ISSN 1025-5834 R&D Projects: GA ČR(CZ) GA201/01/1201 Institutional research plan: CEZ:AV0Z10190503 Keywords : extrapolation * Lebesgue spaces * small Lebesgue spaces Subject RIV: BA - General Mathematics Impact factor: 0.349, year: 2004

  17. Big Bang, Blowup, and Modular Curves: Algebraic Geometry in Cosmology

    Science.gov (United States)

    Manin, Yuri I.; Marcolli, Matilde

    2014-07-01

    We introduce some algebraic geometric models in cosmology related to the ''boundaries'' of space-time: Big Bang, Mixmaster Universe, Penrose's crossovers between aeons. We suggest to model the kinematics of Big Bang using the algebraic geometric (or analytic) blow up of a point x. This creates a boundary which consists of the projective space of tangent directions to x and possibly of the light cone of x. We argue that time on the boundary undergoes the Wick rotation and becomes purely imaginary. The Mixmaster (Bianchi IX) model of the early history of the universe is neatly explained in this picture by postulating that the reverse Wick rotation follows a hyperbolic geodesic connecting imaginary time axis to the real one. Penrose's idea to see the Big Bang as a sign of crossover from ''the end of previous aeon'' of the expanding and cooling Universe to the ''beginning of the next aeon'' is interpreted as an identification of a natural boundary of Minkowski space at infinity with the Big Bang boundary.

  18. Techniques to sort Bessel beams

    CSIR Research Space (South Africa)

    Dudley, Angela L

    2013-09-01

    Full Text Available properties such as their ability to propagate diffraction-free over a finite distance [12-21] and reconstruct after encountering an obstacle [22]. Exploiting these properties of Bessel beams will make them very useful in the field of long-range, broad.... Fig. 1. Case 1, column A: Annular rings (Fourier transform of Bessel beams) of the same radius but different azimuthal components (l = -5 and l = +5) are mapped to transverse momentum modes represented by the linear phase variations in column B. A...

  19. Electron beam writing on semiconductors

    International Nuclear Information System (INIS)

    Bierhenke, H.; Kutzer, E.; Pascher, A.; Plitzner, H.; Rummel, P.; Siemens A.G., Muenchen; Siemens A.G., Muenchen

    1979-08-01

    Reported are the results of the 3 1/2 year research project 'Electron beam Writing on Semiconductors'. Work has been done in the field of direct wafer exposure techniques, and of mask making. Described are resist technology, setting up of a research device, exploration of alignment procedures, manufacturing of devices and their radiation influence. Furthermore, investigations and measurements of an electron beam machine bought for mask making purposes, the development of LSI-circuits with this machine, the software necessary and important developments of digital subsystems are reported. (orig.) [de

  20. Quantized beam shifts in graphene

    Energy Technology Data Exchange (ETDEWEB)

    de Melo Kort-Kamp, Wilton Junior [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Sinitsyn, Nikolai [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dalvit, Diego Alejandro Roberto [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-10-08

    We predict the existence of quantized Imbert-Fedorov, Goos-Hanchen, and photonic spin Hall shifts for light beams impinging on a graphene-on-substrate system in an external magnetic field. In the quantum Hall regime the Imbert-Fedorov and photonic spin Hall shifts are quantized in integer multiples of the fine structure constant α, while the Goos-Hanchen ones in multiples of α2. We investigate the influence on these shifts of magnetic field, temperature, and material dispersion and dissipation. An experimental demonstration of quantized beam shifts could be achieved at terahertz frequencies for moderate values of the magnetic field.

  1. Electron beam processing of polymers

    International Nuclear Information System (INIS)

    Silva, Leonardo G. Andrade e; Dias, Djalma B.; Calvo, Wilson A.P.; Miranda, Leila F. de

    2011-01-01

    The aim of this work is the use of electron beam produced by industrial electron accelerators to process polymers. There are several applications, such as, irradiation of wires and electric cables for automotive, aerospace, household appliance, naval and computing industries. The effect of different radiation doses in low density polyethylene (LDPE) was also studied. After irradiation and crosslinking it was thermally expanded forming LDPE foam. In addition, poly(N-vinyl-2-pyrrolidone) (PVP) hydrogels using electron beam processing were prepared. In all cases studied crosslinking percentages of the samples were determined. (author)

  2. Prospects for ion beam fusion

    Energy Technology Data Exchange (ETDEWEB)

    Martin, R.L.

    1977-01-01

    The promise of pellet fusion by high energy heavy ions has evolved very rapidly, partly because of prior pellet work in the laser and e beam programs and partly because of an inherently good match to the application. ERDA sponsored a summer study in 1976 which has had a significant impact on the direction the ion beam fusion program has evolved. Experimental R and D work has been initiated in three of the U.S. accelerator laboratories. Argonne's development program is described. This development work, if successful, should lead to a great deal of confidence that the concept of pellet fusion by high energy heavy ions is indeed practical.

  3. Low intensity beam target unit

    CERN Multimedia

    CERN PhotoLab

    1976-01-01

    This is a wheel fitted with many targets around its periphery (each with three longitudinally arranged thin rods) of which one is placed into the beam via a rotation of the wheel. Upstream of each target is placed a luminescent screen, aligbed on each target axis and viewed with a TV camera, to make sure that one is hitting the target. This target unit was probably used to study target's behaviour (like beam heating). Gualtiero Del Torre stands on the left, Pierre Gerdil on the right.

  4. Getting ready for SPS beam

    CERN Multimedia

    CERN PhotoLab

    1977-01-01

    View from downstream of the WA7 experiment along beam H1B. In the foreground are scintillator hodoscopes and immediately behind them, is a threshold Cerenkov counter, standing on its edge. The WA7 control hut is located on the right, over the concrete shielding blocks. Still more right, the other branch of the H1 beam, E1A/H1A, runs towards the Omega Facility. WA7 by the CERN-Genoa-LAPP, Annecy-Niels Bohr Institute, Copenhagen-Oslo, University College, London Collaboration was meant to study two-body reactions at large transverse momentum.

  5. Non-Diffractive Tractor Beams

    DEFF Research Database (Denmark)

    Novitsky, Andrey; Gao, Dongliang; Gorlach, Alexey A.

    2017-01-01

    momentum to particles in the backward direction. The amplified forward scattering is achieved through the interaction of multipoles, conventionally electric and magnetic dipole moments. In this talk we give an overview of the tractor beams in optics, acoustics, classical and quantum mechanics. We...... demonstrate how to ease the conditions required in experiment for realization of the optical tractor beams using the cylindrical objects. We pay a particular attention to the case of the pulling optical force due to the interaction of magnetic dipole and quadrupole moments....

  6. Radioactive Ion Beams and Radiopharmaceuticals

    Science.gov (United States)

    Laxdal, R. E.; Morton, A. C.; Schaffer, P.

    2014-02-01

    Experiments performed at radioactive ion beam facilities shed new light on nuclear physics and nuclear structure, as well as nuclear astrophysics, materials science and medical science. The many existing facilities, as well as the new generation of facilities being built and those proposed for the future, are a testament to the high interest in this rapidly expanding field. The opportunities inherent in radioactive beam facilities have enabled the search for radioisotopes suitable for medical diagnosis or therapy. In this article, an overview of the production techniques and the current status of RIB facilities and proposals will be presented. In addition, accelerator-generated radiopharmaceuticals will be reviewed.

  7. Comparison of beam-position-transfer functions using circular beam-position monitors

    International Nuclear Information System (INIS)

    Gilpatrick, J.D.

    1997-01-01

    A cylindrical beam-position monitor (BPM) used in many accelerator facilities has four electrodes on which beam-image currents induce bunched-beam signals. These probe-electrode signals are geometrically configured to provide beam-position information about two orthogonal axes. An electronic processor performs a mathematical transfer function (TF) on these BPM-electrode signals to produce output signals whose time-varying amplitude is proportional to the beam's vertical and horizontal position. This paper will compare various beam-position TFs using both pencil beams and will further discuss how diffuse beams interact with some of these TFs

  8. Transverse beam shape measurements of intense proton beams using optical transition radiation

    Energy Technology Data Exchange (ETDEWEB)

    Scarpine, Victor E.; /Fermilab

    2012-03-01

    A number of particle physics experiments are being proposed as part of the Department of Energy HEP Intensity Frontier. Many of these experiments will utilize megawatt level proton beams onto targets to form secondary beams of muons, kaons and neutrinos. These experiments require transverse size measurements of the incident proton beam onto target for each beam spill. Because of the high power levels, most beam intercepting profiling techniques will not work at full beam intensity. The possibility of utilizing optical transition radiation (OTR) for high intensity proton beam profiling is discussed. In addition, previous measurements of OTR beam profiles from the NuMI beamline are presented.

  9. Operational Performance of LCLS Beam Instrumentation

    International Nuclear Information System (INIS)

    Loos, Henrik; Akre, R.; Brachmann, A.; Coffee, R.; Decker, F.-J.; Ding, Y.; Dowell, D.; Edstrom, S.; Emma, P.; Fisher, A.; Frisch, J.; Gilevich, S.; Hays, G.; Hering, Ph.; Huang, Z.; Iverson, R.; Messerschmidt, M.; Miahnahri, A.; Moeller, S.; Nuhn, H.-D.; Ratner, D.

    2010-01-01

    The Linac Coherent Light Source (LCLS) X-ray FEL utilizing the last km of the SLAC linac has been operational since April 2009 and finished its first successful user run last December. The various diagnostics for electron beam properties including beam position monitors, wire scanners, beam profile monitors, and bunch length diagnostics are presented as well as diagnostics for the X-ray beam. The low emittance and ultra-short electron beam required for X-ray FEL operation has implications on the transverse and longitudinal diagnostics. The coherence effects of the beam profile monitors and the challenges of measuring fs long bunches are discussed.

  10. Operational Performance of LCLS Beam Instrumentation

    Energy Technology Data Exchange (ETDEWEB)

    Loos, Henrik; Akre, R.; Brachmann, A.; Coffee, R.; Decker, F.-J.; Ding, Y.; Dowell, D.; Edstrom, S.; Emma, P.; Fisher, A.; Frisch, J.; Gilevich, S.; Hays, G.; Hering, Ph.; Huang, Z.; Iverson, R.; Messerschmidt, M.; Miahnahri, A.; Moeller, S.; Nuhn, H.-D.; Ratner, D.; /SLAC /LLNL, Livermore

    2010-06-15

    The Linac Coherent Light Source (LCLS) X-ray FEL utilizing the last km of the SLAC linac has been operational since April 2009 and finished its first successful user run last December. The various diagnostics for electron beam properties including beam position monitors, wire scanners, beam profile monitors, and bunch length diagnostics are presented as well as diagnostics for the X-ray beam. The low emittance and ultra-short electron beam required for X-ray FEL operation has implications on the transverse and longitudinal diagnostics. The coherence effects of the beam profile monitors and the challenges of measuring fs long bunches are discussed.

  11. Recent developments for beam intensity increase operation

    International Nuclear Information System (INIS)

    Andre, T.; Anger, P.; Baelde, J.L.; Baumgarten, R.; Doutressoulles, C.; Ducoudret, B.; Etaix, G.; Jamet, C.; Mariette, C.; Petit, E.; Tichoux, G.

    1999-01-01

    The aim of the beam intensity increase operation (THI project) is to multiply the present intensities for lightest ions by a factor of fifteen in order to reach maximum power of six kilowatts. The main objective is the production of large amounts of rare isotopes, either with SISSI (device intended for producing radioactive beams), or with SPIRAL (production and acceleration of radioactive ion beams). As part of this THI project, new developments have been required such as spiral scanners, for beam profile measurements, and safety system to protect equipments against beam loses. Other developments are being carried on to improve the high intensity beam operation. (authors)

  12. Beam halo studies in LEHIPA DTL

    Science.gov (United States)

    Roy, S.; Pande, R.; Rao, S. V. L. S.; Krishnagopal, S.; Singh, P.

    2015-11-01

    The Low Energy High Intensity Proton Accelerator (LEHIPA) project at Bhabha Atomic Research Centre (BARC) consists of a 20 MeV, 30 mA proton linac. The accelerator comprises of a 3 MeV Radio Frequency Quadrupole (RFQ) and a 20 MeV Drift Tube Linac (DTL). In such high intensity accelerators, beam halos are of concern as they not only cause an increase in emittance, but also lead to beam loss and radio activation. We have studied the effect of beam mismatch at the DTL input on halo formation and propagation. The particle core model is used to excite the three envelope eigen modes; the quadrupole mode, the fast mode and the slow mode by giving input beam mismatch. These modes get damped as the beam progresses through the DTL. The damping mechanism is clearly Landau damping and leads to increase in rms emittance of the beam. The evolution of these modes and the corresponding increase in beam emittance and maximum beam extent, as the beam propagates through the DTL, has been studied for different space charge tunes. The halo parameter based on the definition of Allen and Wangler has been calculated. It is seen that beam halos are very important for LEHIPA DTL, even at 20 MeV and leads to emittance and beam size increase and also to beam loss in some cases. The longitudinal halo is present even without mismatch and transverse halos arise in the presence of beam mismatch.

  13. Beam Interlocks for LHC and SPS

    CERN Document Server

    Dinius, A; Gimeno-Vicente, J; Nouchi, P; Puccio, B; Schmidt, R; Wenninger, J

    2003-01-01

    The Large Hadron Collider at CERN (LHC) will operate at 7 TeV/c with a luminosity of 10 cms. This requires two beams with about 3^10 protons/beam, corresponding to a stored energy of about 350 MJ, sufficient to heat and melt 500 kg of copper. Protection of equipment from damage in case of uncontrolled beam losses is challenging. Injection of the beam from the SPS to the LHC could already damage equipment and is only permitted when all LHC systems are correctly prepared. In case of an uncontrolled loss of the circulating LHC beams, it is required to extract the beams into a specially designed target as soon as possible. Beam loss monitors and equipment for hardware surveillance are distributed around the 26 km long accelerator. In case of failures or beam losses, the beam interlock system is informed and sends a dump request to the beam dumping system. The beam interlock system also inhibits injection when the LHC is not ready for beam. In this paper the requirements for the beam interlock system are discussed...

  14. Tau physics with polarized beams

    Energy Technology Data Exchange (ETDEWEB)

    Daoudi, M.

    1995-11-01

    We present the first results on tau physics using polarized beams. These include measurements of the {tau} Michel parameters {xi} and {xi}{delta} and the {tau} neutrino helicity h{sub {nu}}. The measurements were performed using the SLD detector at the Stanford Linear Collider (SLC).

  15. Four-block beam collimator

    CERN Document Server

    CERN PhotoLab

    1977-01-01

    The photo shows a four-block collimator installed on a control table for positioning the alignment reference marks. Designed for use with the secondary beams, the collimators operated in vacuum conditions. The blocks were made of steel and had a standard length of 1 m. The maximum aperture had a square coss-section of 144 cm2. (See Annual Report 1976.)

  16. PLT neutral beam injection systems

    International Nuclear Information System (INIS)

    Menon, M.M.; Barber, G.C.; Blue, C.W.

    1979-01-01

    A brief description of the Princeton Large Torus (PLT) neutral beam injection system is given and its performance characteristics are outlined. A detailed operational procedure is included, as are some tips on troubleshooting. Proper operation of the source is shown to be a crucial factor in system performance

  17. MPS beam control software architecture

    International Nuclear Information System (INIS)

    Krauter, K.; Crane, M.

    1993-04-01

    The new Machine Protection System (MPS) now being tested at SLAC has a beam control subsystem resident in processors located close to the beam monitoring devices within the machine. There are two types of beam control micros: Algorithm Processors (AP's) which collect and evaluate data from monitoring devices, and a Supervisor (SUPE) which collects and evaluates data from all the AP's. The SUPE also receives the global machine beamcode indicating beam presence, and passes it on to the AP's. The SUPE receives the beamcode pattern from the Master Pattern Generator (MPG) via a shared-memory communication link. MIL-1553 serial communication is used between the SUPE and the AP's, and between the AP's and the monitoring devices. Multitasking software is used to allow high priority handling of data evaluation and low priority handling of host/user interfacing and event reporting. Pipelining of data between acquisition and evaluation and reporting is used to accomodate the processing capacity, while still supporting full processing at the 360Hz broadcast rate of the beamcode pattern

  18. Absolute intensities of supersonic beams

    International Nuclear Information System (INIS)

    Beijerinck, H.C.W.; Habets, A.H.M.; Verster, N.F.

    1977-01-01

    In a molecular beam experiment the center-line intensity I(0) (particles s -1 sterad -1 ) and the flow rate dN/dt (particles s -1 ) of a beam source are important features. To compare the performance of different types of beam sources the peaking factor, kappa, is defined as the ratio kappa=π(I(0)/dN/dt). The factor π is added to normalize to kappa=1 for an effusive source. The ideal peaking factor for the supersonic flow from a nozzle follows from continuum theory. Numerical values of kappa are available. Experimental values of kappa for an argon expansion are presented in this paper, confirming these calculations. The actual center-line intensity of a supersonic beam source with a skimmer is reduced in comparison to this ideal intensity if the skimmer shields part of the virtual source from the detector. Experimental data on the virtual source radius are given enabling one to predict this shielding quantitatively. (Auth.)

  19. History of the polarized beam

    Energy Technology Data Exchange (ETDEWEB)

    Parker, E F

    1979-01-01

    In 1973, the first high energy polarized proton beam was developed at the Argonne Zero Gradient Synchrotron (ZGS). It operated very successfully and productively until 1979 when the ZGS was shut down permanently. This report describes the development, characteristics, and operations of this facility.

  20. Electron beam micromachining of plastics

    Czech Academy of Sciences Publication Activity Database

    Dupák, Libor

    2014-01-01

    Roč. 49, 5-6 (2014), s. 310-314 ISSN 0861-4717 R&D Projects: GA MŠk(CZ) LO1212; GA MŠk ED0017/01/01; GA MŠk EE.2.3.20.0103 Institutional support: RVO:68081731 Keywords : micromachining of plastics * Electron beam Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering