Betatron electromagnet is described. It enables to increase focusing forces. For this purpose the ridges of one pole are located above the gaos between the redges of the second .oole at equal distances from two neighboring ridges of this pole. Azimuthal periodic controlling field with vertical symmetry plane forms in operation gap. Increase of focusing forces results to the growth of accelerated particle amount per cycle
On the basis of the comparative review of the methods for the betatron tune measurement in cyclic accelerators of synchrotrons type, the research of these methods is carried out from the point of view of their applicability to Nuclotron. Both methods using measurement of the statistical fluctuations of the beam current (Schottky noise) and methods using coherent beam excitation have been discussed. The emphasis is on the final results of importance for the tune measurement practice. Signal processing is briefly discussed too
Radiation damping of betatron oscillations
The emission of synchrotron radiation damps the incoherent betatron oscillations of a pinched beam, causing its radius to shrink. However, the rate of shrinkage is small compared with the rate of expansion caused by scattering for typical propagation parameters
Betatron Tune Determination: Interpolation Formulas
Fabre, Ignacio
2015-01-01
In order to obtain accurate estimations of the betatron tune, interpolation formulas have been derived that give estimates that approaches the real tune as $1/N^2$ and $1/N^4$ for signals of constant amplitude. In this document interpolation formulas for signals with exponential decaying amplitudes are derived, and its errors are analyzed as a function of the input signal size and the decay constant. We obtain the same scaling law of $1/N^2$ for the case of constant amplitude, and an improvement over the previous methods in the case of decaying amplitude. Lower boundaries for the errors were observed, and methods for surpass this were analyzed.
Betatron radiation from density tailored plasmas
Ta Phuoc, Kim; Esarey, E.; Leurent, V.; Cormier-Michel, E.; Geddes, C.G.R.; Schroeder, C.B.; Rousse, A.; Leemans, W.P.
2009-04-11
In laser wakefield accelerators, electron motion is driven by intense forces that depend on the plasma density. Transverse oscillations in the accelerated electron orbits produce betatron radiation. The electron motion and the resulting betatron radiation spectrum can therefore be controlled by shaping the plasma density along the orbit of the electrons. Here, a method based on the use of a plasma with a longitudinal density variation (density depression or step) is proposed to increase the transverse oscillation amplitude and the energy of the electrons accelerated in a wakefield cavity. For fixed laser parameters, by appropriately tailoring the plasma profile, the betatron radiation emitted by these electrons is significantly increased in both flux and energy.
Dispersion and betatron matching into the linac
In high energy linear colliders, the low emittance beam from a damping ring has to be preserved all the way to the linac, in the linac and to the interaction point. In particular, the Ring-To-Linac (RTL) section of the SLAC Linear Collider (SLC) should provide an exact betatron and dispersion match from the damping ring to the linac. A beam with a non-zero dispersion shows up immediately as an increased emittance, while with a betatron mismatch the beam filaments in the linac. Experimental tests and tuning procedures have shown that the linearized beta matching algorithms are insufficient if the actual transport line has some unknown errors not included in the model. Also, adjusting quadrupole strengths steers the beam if it is offset in the quadrupole magnets. These and other effects have lead to a lengthy tuning process, which in the end improves the matching, but is not optimal. Different ideas will be discussed which should improve this matching procedure and make it a more reliable, faster and simpler process. 5 refs., 2 figs
Stabilization of betatron tune in Indus-2
Jena, Saroj; Agrawal, R K; Ghodke, A D; Fatnani, Pravin; Puntambekar, T A
2013-01-01
Indus-2 is a synchrotron radiation source which is operational at RRCAT, Indore; India. It is essentially pertinent in any synchrotron radiation facility to store the electron beam without beam loss. During the day to day operation of Indus-2 storage ring difficulty was being faced in accumulating higher beam current. After examining, it was found that the working point was shifting from its desired value during accumulation. For smooth beam accumulation, a fixed desired tune in both horizontal and vertical plane plays a great role in avoiding the beam loss via resonance process. This demanded a betatron tune feedback system to be put in storage ring and after putting ON this feedback, the beam accumulation was smooth. The details of this feedback and its working principle are described in this paper.
A Thick Target for Synchrotrons and Betatrons
McMillan, E. M.
1950-09-19
If a wide x-ray beam from an electron synchrotron or betatron is desired, in radiographic work with large objects for example, the usually very thin target may be replaced by a thick one, provided the resulting distortion of the x-ray spectrum due to multiple radiative processes is permissible. It is difficult to make the circulating electron beam traverse a thick target directly because of the small spacing between successive turns. Mounting a very thin beryllium, or other low-z material, fin on the edge of the thick target so that the fin projects into the beam will cause the beam to lose sufficient energy, and therefore radium, to strike the thick target the next time around. Sample design calculations are given.
Quadrupole betatron accelerator for high current ion beams
Properties of a strong non-neutral ion ring in a quadrupole betatron field are investigated. Superimposed on the axial betatron field, it is shown that the quadrupole field is necessary for the stability of the orbits where the self-fields of the ion ring are not negligible. A closed algebraic expression for the ion limiting current is obtained in terms of the quadarupole field intensity, the channel radius, the transverse temperature of ion beam, and the strength of betatron field. According to the theoretical calculation, high energy ion beam with its current order of one kiloampere can easily be attainable
Application of a Betatron in Photonuclear Activation Analysis
The present study concerns the determination of fluorine, iodine, lead and mercury by means of photonuclear activation technique using a betatron. The detection limit obtained for the elements in the above given sequence amounted to 3, 50, 400 and 15 μg respectively. The technique has been applied in the determination of iodine in pharmaceuticals. A rotating sample holder device was inserted in the Bremsstrahlung beam of the betatron in order to ensure uniform irradiation of the samples
Betatron radiation from laser Wakefield acceleration in a plasma channel
Laser Wakefield acceleration by a high-power laser pulse and a plasma has attracted lots of attention in recent years as it can generate quasi-monoenergetic high-energy electron beams and may be used for a compact x-ray source on a table-top scale. In the laser wakefield acceleration, plasma electrons can be self-injected into the acceleration phase of the wake wave and they are accelerated with an extremely high gradient in the longitudinal direction. In addition to the longitudinal acceleration, the wake wave also gives an ultra-strong focusing force in the transverse direction. As a result, the accelerated electrons execute the betatron oscillations which can produce the betatron radiation. We propose a method to increase the betatron oscillation amplitude by off-axis injection of a laser pulse into a capillary plasma waveguide. The capillary plasma waveguide has been used only for optical guiding and electron acceleration, where the transverse plasma density profile is nearly parabolic. In our work, we found that the betatron oscillation amplitude can be significantly increased by off-axis injection of the laser pulse into the capillary plasma waveguide, which can be utilized for generation of shorter wavelength X-ray radiation. In order to demonstrate the proposed idea for increasing the betatron oscillation amplitude, we performed two-dimensional (2D) particle in-cell (PIC) simulations in addition to analytical studies. (author)
Study of synchro-betatron coupling in IPNS upgrade RCS
The 2 GeV rapidly-cycling synchrotron (RCS) of the proposed 1-MW spallation neutron source upgrade has 16 dispersion-free straight sections and eight straight sections with a dispersion of approximately 1 m. Six of the ten rf cavities are located in dispersion-free straight sections, and the remainder are located in the non-dispersion-free straight sections. The possibility of exciting synchro-betatron resonances is investigated in this paper. It is found that the effect of the coupling is not important to the RCS. Synchro-betatron resonances are driven in single beams by position-dependent energy gains from the accelerating fields. A primary cause is the dispersion at the location of the rf cavities. Longitudinal and transverse motions are coupled due to a transverse deflection associated with a particle crossing the rf cavity gap. This changes the equilibrium orbit and excites betatron oscillations
Connection for dose rate control of betatron gamma beam
The connection is based on a single-channel controller consisting of a microcomputer which prior to the start of control will find the region of the absolute maximum dose rate of the betatron gamma beam. In the course of control it will evaluate data on the level of dose rate from the betatron, and on the basis of a comparison of the previous and current condition will change the moment of injecting electrons into the acceleration chamber by one step. The control algorithm is described. The heating cathode current of the injection gun is adjusted manually. The controller may be connected to the betatron without any adjustments to the control console. The described connection allows to achieve good stability of maximum dose rate values. (J.B.). 2 figs
Linear betatron coupling and decoupling in Indus-2 storage ring
In a synchrotron light source such as Indus-2, the vertical emittance is mainly governed by transverse betatron coupling. The coupling is generated due to rotational errors of normal lattice quadrupoles. Vertical emittance of the beam can affect the lifetime of the beam as well as spectral brightness of the radiated photon beam. Thus coupling control is also necessary in a light source. In this paper we present the betatron tune split, emittance coupling ratio and transfer of beam emittance from one transverse plane to another in presence of rotational errors of normal lattice quadrupoles in Indus-2. The results of emittance coupling and decoupling are also discussed. (author)
Probing warm dense silica with betatron radiation - Oral Presentation
Kotick, Jordan [SLAC National Accelerator Lab., Menlo Park, CA (United States)
2015-08-24
Laser wakefield acceleration (LWFA) has been shown to produce short X-ray pulses from oscillations of electrons within the plasma wake. These betatron X-rays pulses have a broad, synchrotron-like energy spectrum and a duration on the order of the driving laser pulse, thereby enabling probing of ultrafast interactions. Using the 1 J, 40fs short-pulse laser at the Matter in Extreme Conditions experimental station at LCLS, we have implemented LWFA to generate and subsequently characterized betatron X-rays. A scintillator and lanex screen were used to measure the charge fluence and energy spectrum of the produced electron beam.
General Spin Precession and Betatron Oscillation in Storage Ring
Fukuyama, Takeshi
2016-01-01
We give the geralized expression of spin precession of extended bunch particles having both anomalous magnetic and electric dipole moments in storage ring. The transversal betatron oscillation formula of the bunch is also given. The latter is the generalization of the Farley's pitch correction \\cite{Farley}, including radial oscillation as well as vertical one. Some useful formulae for muon storage ring are discussed in appendix.
General spin precession and betatron oscillation in storage rings
Fukuyama, Takeshi
2016-07-01
Spin precession of particles having both anomalous magnetic and electric dipole moments (EDMs) is considered. We give the generalized expression of spin precession of these particles injected with transversal extent in magnetic storage rings. This is the generalization of the Farley’s pitch correction [F. J. N. Farley, Phys. Lett. B 42, 66 (1972)], including radial oscillation as well as vertical one. The transversal betatron oscillation formulae of these particles are also reproduced.
Single-shot betatron source size measurement from a laser-wakefield accelerator
Köhler, A.; Zarini, O.; Jochmann, A.; Irman, A.; Schramm, U.; 10.1016/j.nima.2016.02.031
2016-01-01
Betatron radiation emitted by accelerated electrons in laser-wakefield accelerators can be used as a diagnostic tool to investigate electron dynamics during the acceleration process. We analyze the spectral characteristics of the emitted Betatron pattern utilizing a 2D x-ray imaging spectroscopy technique. Together with simultaneously recorded electron spectra and x-ray images, the betatron source size, thus the electron beam radius, can be deduced at every shot.
Investigation of betatron instability in a wiggler pumped ion-channel free electron laser
Raghavi, A [Physics Department, Payame Noor University, 19395-4697 (Iran, Islamic Republic of); Mehdian, H, E-mail: Raghavi@tmu.ac.ir, E-mail: Mehdian@tmu.ac.ir [Department of Physics, Teacher Training University, Tehran (Iran, Islamic Republic of)
2011-10-15
Betatron emission from an ion-channel free electron laser in the presence of a helical wiggler pump and in the high gain regime is studied. The dispersion relation and the frequency of betatron emission are derived. Growth rate is illustrated and maximum growth rate as a function of ion-channel density is considered. Finally, the relation between beam energy, the density of ion channel and the region of betatron emission is discussed.
Bruno Touschek, from Betatrons to Electron-positron Colliders
Bernardini, Carlo; Pellegrini, Claudio
2015-01-01
Bruno Touschek's life as a physicist spanned the period from World War II to the 1970s. He was a key figure in the developments of electron-positron colliders, storage rings, and gave important contributions to theoretical high energy physics. Storage rings, initially developed for high energy physics, are being widely used in many countries as synchrotron radiation sources and are a tool for research in physics, chemistry, biology environmental sciences and cultural heritage studies. We describe Touschek's life in Austria, where he was born, Germany, where he participated to the construction of a betatron during WWII, and Italy, where he proposed and led to completion the first electron-positron storage ring in 1960, in Frascati. We highlight how his central European culture influenced his life style and work, and his main contributions to physics, such as the discovery of the Touschek effect and beam instabilities in the larger storage ring ADONE.
PRINCIPLE OF SKEW QUADRUPOLE MODULATION TO MEASURE BETATRON COUPLING.
LUO.Y.PILAT,F.ROSER,T.ET AL.
2004-07-05
The measurement of the residual betatron coupling via skew quadrupole modulation is a new diagnostics technique that has been developed and tested at the Relativistic Heavy Ion Collider (RHIC) as a very promising method for the linear decoupling on the ramp. By modulating the strengths of different skew quadrupole families the two eigentunes are precisely measured with the phase lock loop system. The projections of the residual coupling coefficient onto the skew quadrupole coupling modulation directions are determined. The residual linear coupling could be corrected according to the measurement. An analytical solution for skew quadrupole modulation based on Hamiltonian perturbation approximation is given, and simulation code using smooth accelerator model is also developed. Some issues concerning the practical applications of this technique are discussed.
Characteristics of betatron radiation from direct-laser-accelerated electrons
Huang, T. W.; Robinson, A. P. L.; Zhou, C. T.; Qiao, B.; Liu, B.; Ruan, S. C.; He, X. T.; Norreys, P. A.
2016-06-01
Betatron radiation from direct-laser-accelerated electrons is characterized analytically and numerically. It is shown here that the electron dynamics is strongly dependent on a self-similar parameter S (≡n/enca0 ) . Both the electron transverse momentum and energy are proportional to the normalized amplitude of laser field (a0) for a fixed value of S . As a result, the total number of radiated photons scales as a02/√{S } and the energy conversion efficiency of photons from the accelerated electrons scales as a03/S . The particle-in-cell simulations agree well with the analytical scalings. It is suggested that a tunable high-energy and high-flux radiation source can be achieved by exploiting this regime.
Betatron Application in Mobile and Relocatable Inspection Systems for Freight Transport Control
Chakhlov, S. V.; Kasyanov, S. V.; Kasyanov, V. A.; Osipov, S. P.; Stein, M. M.; Stein, A. M.; Xiaoming, Sun
2016-01-01
Accelerators with energy level up to 4 MeV having high level of penetration ability by steel equivalent are the popular to control oversize cargo transported by road, by railway and by river. Betatron's usage as cyclic induction accelerator has some advantages in comparison with linear accelerators and other sources. Tomsk Polytechnic University has developed many types of betatrons, most of them are being produced by separate affiliated company " Foton ". Article is shown the results of application of the betatrons in inspection custom systems.
Algorithms for a Precise Determination of the Betatron Tune
Bartolini, R; Giovannozzi, Massimo; Todesco, Ezio; Scandale, Walter
1996-01-01
In circular accelerators the precise knowledge of the betatron tune is of paramount importance both for routine operation and for theoretical investigations. The tune is measured by sampling the transverse position of the beam for N turns and by performing the FFT of the stored data. One can also evaluate it by computing the Average Phase Advance (APA) over N turns. These approaches have an intrinsic error proportional to 1/N. However, there are special cases where either a better precision or a faster measurement is desired. More efficient algorithms can be used, as those suggested by E.Asseo [1] and recently by J. Laskar [2]. They provide tune estimates by far more precise than those of a plain FFT, as discussed in Ref. [3]. Another important isssue is the effect of the finite resolution of the instrumentation used to measure the beam position. This introduces a noise and the frequency response of the beam is modified [4,5} thus reducing the precision by which the tune is determined. In Section 2 we recall ...
Kotick, Jordan; Schumaker, Will; Condamine, Florian; Albert, Felicie; Barbrel, Benjamin; Galtier, Eric; Granados, Eduardo; Ravasio, Alessandra; Glenzer, Siegfried
2015-11-01
Laser wakefield acceleration (LWFA) has been shown to produce short X-ray pulses from betatron oscillations of electrons within the plasma wake. These betatron X-rays pulses have a broad, synchrotron-like energy spectrum and a duration on the order of the driving laser pulse, thereby enabling probing of ultrafast interactions. Using the 1 J, 40fs short-pulse laser at the Matter in Extreme Conditions experimental station at LCLS, we have implemented LWFA to generate and subsequently characterized betatron X-rays. Notch filtering and single photon counting techniques were used to measure the betatron X-ray spectrum while the spatial profile was measured using X-ray CCDs and image plates. We used an ellipsoidal mirror to focus the soft betatron X-rays for pump-probe studies on various targets in conjunction with LCLS X-ray and optical laser pulses. This experimental platform provides the conditions necessary to do a detailed study of warm-dense matter dynamics on the ultrafast time-scale.
Measurement and calculation of betatron frequency in synchrotron of proton beam therapy
Downsizing is necessary for the spread of proton therapy. We developed a compact synchrotron for system downsizing. The new synchrotron has a four-folding symmetric lattice, and its circumference is 18m. This synchrotron has the quadrupole magnets of the single system, which change betatron frequency between injection and extraction. Under this operation scheme, it is necessary to put betatron frequency, determined by edge focus of bending magnets, in ±0.01 ranges. Therefore, the bending magnet shape was determined by three-dimensional magnetic field calculation and particle-tracking. As result, measured betatron frequency at flattop became the difference of less than 0.01 for designed value. And, stable injection, acceleration and extraction were realized. (author)
Betatron motion with coupling of horizontal and vertical degrees of freedom
The Courant-Snyder parameterization of one-dimensional linear betatron motion is generalized to two-dimensional coupled linear motion. To represent the 4 x 4 symplectic transfer matrix the following ten parameters were chosen: four beta-functions, four alpha-functions and two betatron phase advances which have a meaning similar to the Courant-Snyder parameterization. Such a parameterization works equally well for weak and strong coupling and can be useful for analysis of coupled betatron motion in circular accelerators as well as in transfer lines. Similarly, the transfer matrix, the bilinear form describing the phase space ellipsoid and the second order moments are related to the eigen-vectors. Corresponding equations can be useful in interpreting tracking results and experimental data
Equations of motion and Hamiltonian for synchrotron oscillations and synchro-betatron coupling
We discuss the equations of motion and Hamiltonian for synchrotron oscillations and synchro-betatron coupling while taking into account the localized nature of RF cavities. We start with differential and difference equations for the phase and energy equations, respectively. We derive approximate differential equations as well as difference equations for mapping from the basic equations. The Hamiltonian formalism developed in this note will help readers to understand the equations of motion from a more formal point of view. It also helps to derive the equations of motion for synchro-betatron coupling. The effect of betatron acceleration is also taken into account in the formalism. Synchrotron radiation effects are only briefly mentioned. Wake-field effects are not treated. This note is based on lectures given at the Accelerator Department of the Graduate University for Advance Studies attached to KEK, but has been extended to include the Hamiltonian formalism. (author)
Analysis of optical klystron wave guide free electron laser with betatron oscillation effects
In this paper, we analyze the effect of the betatron oscillation on spontaneous emission and gain spectrum of an optical klystron wave guide free electron laser. The analysis also includes the effects of length mismatch of the two undulator sections of the klystron configuration. We observe that intensity and gain can be change with length mismatch parameter without changing the central emission frequency. - Highlights: • We analyse effect of length mismatch of two undulator section of optical klystron. • With length mismatch betatron effect is analyse on optical klystron. • The length mismatch does not affect central emission frequency. • With increase in length mismatch gain decreases. • With increase of betatron oscillation gain decreases
Second order effects of a sextupolar field on betatron oscillations in a storage ring
Calculations concerning the betatron oscillations in a storage ring lattice comprising a lumped element sextupole field are presented. The method used is based on the second order approximation of the averaging method. The existence of singular points inside the region of the phase space defined by the separatrix is assumed. Formula are given permitting the calculations of the size of the corresponding intersecting invariant curves and a simple expression is deduced for the betatron tune shift. Numerical application is made, the results are compared to those obtained by a tracking program. A good agreement between them is noticed
Analogical optical modeling of the asymmetric lateral coherence of betatron radiation.
Paroli, B; Chiadroni, E; Ferrario, M; Potenza, M A C
2015-11-16
By exploiting analogical optical modeling of the radiation emitted by ultrarelativistic electrons undergoing betatron oscillations, we demonstrate peculiar properties of the spatial coherence through an interferometric method reminiscent of the classical Young's double slit experiment. The expected effects due to the curved trajectory and the broadband emission are accurately reproduced. We show that by properly scaling the fundamental parameters for the wavelength, analogical optical modeling of betatron emission can be realized in many cases of broad interest. Applications to study the feasibility of future experiments and to the characterization of beam diagnostics tools are described. PMID:26698473
Measuring the angular dependence of betatron x-ray spectra in a laser-wakefield accelerator
Albert, F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Pollock, B. B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Shaw, J. L. [Univ. of California, Los Angeles, CA (United States); Marsh, K. A. [Univ. of California, Los Angeles, CA (United States); Ralph, J. E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Chen, Y. -H. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Alessi, D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Pak, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Clayton, C. E. [Univ. of California, Los Angeles, CA (United States); Glenzer, S. H. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Joshi, C. [Univ. of California, Los Angeles, CA (United States)
2014-07-22
This paper presents a new technique to measure the angular dependence of betatron x-ray spectra in a laser-wakefield accelerator. Measurements are performed with a stacked image plates spectrometer, capable of detecting broadband x-ray radiation up to 1 MeV. It can provide measurements of the betatron x-ray spectrum at any angle of observation (within a 40 mrad cone) and of the beam profile. A detailed description of our data analysis is given, along with comparison for several shots. As a result, these measurements provide useful information on the dynamics of the electrons are they are accelerated and wiggled by the wakefield.
The use of small-size PMB-6E betatron for radiation therapy of oncologic patients
Results of applying the smallsize betatron PMB-6E for radiation therapy of oncologic patients, are presented. The application of the betatron is most advisable in cases of tumors of skin, soft tissues, red lip edge, in some patients with mouth mucosa cancer, as well as in cases of local relapse of mammary gland cancer and other surface tumors. One of the limitations for the treatment of tumors of mouth mucosa with fast neutrons are the dimensions of the pathological hotbed, which exceed the diameter of collimators or a considerable depth of infiltration in the surrounding tissues
Simple analytical formulae are presented for a quick optimization of the Free Electron Laser (FEL) gain length for given values of radiation wavelength, electron beam current, normalized transverse emittance and energy spread. The optimization parameters include the gap size of the wiggler, the wiggler period and the betatron wavelength (in the case of external focusing). The method is based on the handy formulae for the FEL gain of a Gaussian beam including the effects of energy spread, emittance, and betatron oscillations of the electron beam. We have found a simple relation between the minimum FEL gain length and the optimum betatron wavelength for given energy spread, emittance, and gap size of the wiggler. When the emittance is about the radiation wavelength divided by 4ρ and the energy spread is negligible, this relation shows that the gain length is optimized if the betatron wavelength is chosen so that the betatron phase advances by a half radian in the gain length
Huang, K.; Li, Y. F.; Li, D. Z.; Chen, L. M.; Tao, M. Z.; Ma, Y.; Zhao, J. R.; Li, M. H.; Chen, M.; Mirzaie, M.; Hafz, N.; Sokollik, T.; Sheng, Z. M.; Zhang, J.
2016-06-01
Ultrafast betatron x-ray emission from electron oscillations in laser wakefield acceleration (LWFA) has been widely investigated as a promising source. Betatron x-rays are usually produced via self-injected electron beams, which are not controllable and are not optimized for x-ray yields. Here, we present a new method for bright hard x-ray emission via ionization injection from the K-shell electrons of nitrogen into the accelerating bucket. A total photon yield of 8 × 108/shot and 108 photons with energy greater than 110 keV is obtained. The yield is 10 times higher than that achieved with self-injection mode in helium under similar laser parameters. The simulation suggests that ionization-injected electrons are quickly accelerated to the driving laser region and are subsequently driven into betatron resonance. The present scheme enables the single-stage betatron radiation from LWFA to be extended to bright γ-ray radiation, which is beyond the capability of 3rd generation synchrotrons.
Huang, K; Li, Y F; Li, D Z; Tao, M Z; Mirzaie, M; Ma, Y; Zhao, J R; Li, M H; Chen, M; Hafz, N; Sokollik, T; Sheng, Z M; Zhang, J
2015-01-01
A new scheme for bright hard x-ray emission from laser wakefield electron accelerator is reported, where pure nitrogen gas is adopted. Intense Betatron x-ray beams are generated from ionization injected K-shell electrons of nitrogen into the accelerating wave bucket. The x-ray radiation shows synchrotron-like spectrum with total photon yield 8$\\times$10$^8$/shot and $10^8$ over 110keV. In particular, the betatron hard x-ray photon yield is 10 times higher compared to the case of helium gas under the same laser parameters. Particle-in-cell simulation suggests that the enhancement of the x-ray yield results from ionization injection, which enables the electrons to be quickly accelerated to the driving laser region for subsequent betatron resonance. Employing the present scheme,the single stage nitrogen gas target could be used to generate stable high brightness betatron hard x-ray beams.
Automatic Correction of Betatron Coupling in the LHC Using Injection Oscillations
Persson, T; Jacquet, D; Kain, V; Levinsen, Y; McAteer, M-J; Maclean, E; Skowronski, P; Tomas, R; Vanbavinckhove, G; Miyamoto, R
2013-01-01
The control of the betatron coupling at injection and during the energy ramp is critical for the safe operation of the tune feedback and for the dynamic aperture. In the LHC every fill is preceded by the injection of a pilot bunch with low intensity. Using the injection oscillations from the pilot bunch we are able to measure the coupling at each individual BPM. The measurement is used to calculate a global coupling correction. The correction is based on the use of two orthogonal knobs which correct the real and imaginary part of the difference resonance term f1001, respectively. This method to correct the betatron coupling has been proven successful during the normal operation of the LHC. This paper presents the method used to calculate the corrections and its performance.
Experimental investigation of a small-sized betatron with superposed magnetization
The aim of the paper is to study possibilities of small-sized betatrons (SSB) with direct current superposed magnetization (DSM). It is shown that DSM permits to decrease the SSB weight and cost of the electromagnet and capacitor storage and to shape the prolonged beam dump. It is noted that the DSM realization has the most expediency in SSB operating in a short-time mode
Positron Source from Betatron X-Rays Emitted in a Plasma Wiggler
Johnson, Devon K; Clayton, Chris; Decker, Franz Josef; Deng, Suzhi; Hogan, Mark; Huang Cheng Kun; Iverson, Richard; Joshi, Chandrashekhar; Katsouleas, Thomas C; Krejcik, Patrick; Lu, Wei; Marsh, Kenneth; Mori, Warren; Muggli, Patric; Oz, Erdem; Siemann, Robert; Walz, Dieter; Zhou, Miaomiao
2005-01-01
In the E-167 plasma wakefield accelerator (PWFA) experiments in the Final Focus Test Beam (FFTB) at the Stanford Linear Accelerator Center (SLAC), an ultra-short, 28.5 GeV electron beam field ionizes a neutral column of Lithium vapor. In the underdense regime, all plasma electrons are expelled creating an ion column. The beam electrons undergo multiple betatron oscillations leading to a large flux of broadband synchrotron radiation. With a plasma density of 3x1017
Vieira, J; Sinha, U
2016-01-01
We explore a plasma based analogue of a helical undulator capable of providing circularly and elliptically polarised betatron radiation. We focus on ionisation injection configurations and in the conditions where the laser pulse driver can force collective betatron oscillations over the whole trapped electron bunch. With an analytical model and by employing three dimensional simulations and radiation calculations, we find that circularly or elliptically polarised laser drivers can force helical betatron oscillations, which produce circularly/elliptically polarised betatron x-rays. We assess the level of polarisation numerically and analytically, and find that the number of circularly polarised photons can be controlled by tuning the laser pulse driver polarisation. We show the production of betatron radiation that is circularly polarised up to < 40% close to regions of maximum photon flux. The total flux of circularly polarised betatron radiation drops for elliptically polarised drivers, and is negligible ...
Jeon, Jong Ho, E-mail: jhjeon07@ibs.re.kr; Nakajima, Kazuhisa, E-mail: naka115@dia-net.ne.jp; Pathak, Vishwa Bandhu; Cho, Myung Hoon; Yoo, Byung Ju; Shin, Kang Woo [Center for Relativistic Laser Science, Institute for Basic Science (IBS), Gwangju 500-712 (Korea, Republic of); Kim, Hyung Taek; Sung, Jae Hee; Lee, Seung Ku; Choi, Il Woo [Center for Relativistic Laser Science, Institute for Basic Science (IBS), Gwangju 500-712 (Korea, Republic of); Advanced Photonics Research Institute, GIST, Gwangju 500-712 (Korea, Republic of); Rhee, Yong Joo [Nuclear Data Center, Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of); Shin, Jung Hun; Jo, Sung Ha [Advanced Photonics Research Institute, GIST, Gwangju 500-712 (Korea, Republic of); Hojbota, Calin; Cho, Byeoung Ick; Nam, Chang Hee [Center for Relativistic Laser Science, Institute for Basic Science (IBS), Gwangju 500-712 (Korea, Republic of); Department of Physics and Photon Science, GIST, Gwangju 500-712 (Korea, Republic of)
2015-12-15
We present a high-flux, broadband gamma-ray spectrometry capable of characterizing the betatron radiation spectrum over the photon energy range from 10 keV to 20 MeV with respect to the peak photon energy, spectral bandwidth, and unique discrimination from background radiations, using a differential filtering spectrometer and the unfolding procedure based on the Monte Carlo code GEANT4. These properties are experimentally verified by measuring betatron radiation from a cm-scale laser wakefield accelerator (LWFA) driven by a 1-PW laser, using a differential filtering spectrometer consisting of a 15-filter and image plate stack. The gamma-ray spectra were derived by unfolding the photostimulated luminescence (PSL) values recorded on the image plates, using the spectrometer response matrix modeled with the Monte Carlo code GEANT4. The accuracy of unfolded betatron radiation spectra was assessed by unfolding the test PSL data simulated with GEANT4, showing an ambiguity of less than 20% and clear discrimination from the background radiation with less than 10%. The spectral analysis of betatron radiation from laser wakefield-accelerated electron beams with energies up to 3 GeV revealed radiation spectra characterized by synchrotron radiation with the critical photon energy up to 7 MeV. The gamma-ray spectrometer and unfolding method presented here facilitate an in-depth understanding of betatron radiation from LWFA process and a novel radiation source of high-quality photon beams in the MeV regime.
We present a high-flux, broadband gamma-ray spectrometry capable of characterizing the betatron radiation spectrum over the photon energy range from 10 keV to 20 MeV with respect to the peak photon energy, spectral bandwidth, and unique discrimination from background radiations, using a differential filtering spectrometer and the unfolding procedure based on the Monte Carlo code GEANT4. These properties are experimentally verified by measuring betatron radiation from a cm-scale laser wakefield accelerator (LWFA) driven by a 1-PW laser, using a differential filtering spectrometer consisting of a 15-filter and image plate stack. The gamma-ray spectra were derived by unfolding the photostimulated luminescence (PSL) values recorded on the image plates, using the spectrometer response matrix modeled with the Monte Carlo code GEANT4. The accuracy of unfolded betatron radiation spectra was assessed by unfolding the test PSL data simulated with GEANT4, showing an ambiguity of less than 20% and clear discrimination from the background radiation with less than 10%. The spectral analysis of betatron radiation from laser wakefield-accelerated electron beams with energies up to 3 GeV revealed radiation spectra characterized by synchrotron radiation with the critical photon energy up to 7 MeV. The gamma-ray spectrometer and unfolding method presented here facilitate an in-depth understanding of betatron radiation from LWFA process and a novel radiation source of high-quality photon beams in the MeV regime
Formation of Field-reversed-Configuration Plasma with Punctuated-betatron-orbit Electrons
Welch, D. R.; Cohen, S. A.; Genoni, T. C.; Glasser, A. H.
2010-06-28
We describe ab initio, self-consistent, 3D, fully electromagnetic numerical simulations of current drive and field-reversed-configuration plasma formation by odd-parity rotating magnetic fields (RMFo). Magnetic-separatrix formation and field reversal are attained from an initial mirror configuration. A population of punctuated-betatron-orbit electrons, generated by the RMFo, carries the majority of the field-normal azimuthal electrical current responsible for field reversal. Appreciable current and plasma pressure exist outside the magnetic separatrix whose shape is modulated by the RMFo phase. The predicted plasma density and electron energy distribution compare favorably with RMFo experiments. __________________________________________________
Demonstration of no feasibility of a crystalline beam in a Betatron Magnet II
This paper investigates the feasibility of a Crystalline Beam in a weak-focusing Betatron Magnet. The curvature effect due to the bending magnet is also investigated. The case of circular one- dimensional string of electrically-charged particles is examined. It is found that the motion is unstable due to the dependence of the precession movement with the radial displacement. That is a form of negative-mass instability which can be avoided with an alternating-focussing structure. The calculation of the particle-particle interaction as well as of the forces due to the external magnetic field is done directly in the laboratory frame
K. Huang; Chen, L. M.; Y. F. Li; D.Z. Li; M. Z. Tao; M. Mirzaie; Y. Ma; J. R. Zhao; M. H. Li; M. Chen; Hafz, N.; Sokollik, T.; Sheng, Z. M.; Zhang, J.
2015-01-01
A new scheme for bright hard x-ray emission from laser wakefield electron accelerator is reported, where pure nitrogen gas is adopted. Intense Betatron x-ray beams are generated from ionization injected K-shell electrons of nitrogen into the accelerating wave bucket. The x-ray radiation shows synchrotron-like spectrum with total photon yield 8$\\times$10$^8$/shot and $10^8$ over 110keV. In particular, the betatron hard x-ray photon yield is 10 times higher compared to the case of helium gas un...
Shpakov, V.; Anania, M. P.; Biagioni, A.; Chiadroni, E.; Cianchi, A.; Curcio, A.; Dabagov, S.; Ferrario, M.; Filippi, F.; Marocchino, A.; Paroli, B.; Pompili, R.; Rossi, A. R.; Zigler, A.
2016-09-01
Recent progress with wake-field acceleration has shown a great potential in providing high gradient acceleration fields, while the quality of the beams remains relatively poor. Precise knowledge of the beam size at the exit from the plasma and matching conditions for the externally injected beams are the key for improvement of beam quality. Betatron radiation emitted by the beam during acceleration in the plasma is a powerful tool for the transverse beam size measurement, being also non-intercepting. In this work we report on the technical solutions chosen at SPARC_LAB for such diagnostics tool, along with expected parameters of betatron radiation.
Quantitative X-Ray Phase-Contrast Microtomography from a Compact Laser Driven Betatron Source
Wenz, J; Khrennikov, K; Bech, M; Thibault, P; Heigoldt, M; Pfeiffer, F; Karsch, S
2014-01-01
X-ray phase-contrast imaging has recently led to a revolution in resolving power and tissue contrast in biomedical imaging, microscopy and materials science. The necessary high spatial coherence is currently provided by either large-scale synchrotron facilities with limited beamtime access or by microfocus X-ray tubes with rather limited flux. X-rays radiated by relativistic electrons driven by well-controlled high-power lasers offer a promising route to a proliferation of this powerful imaging technology. A laser-driven plasma wave accelerates and wiggles electrons, giving rise to brilliant keV X-ray emission. This so-called Betatron radiation is emitted in a collimated beam with excellent spatial coherence and remarkable spectral stability. Here we present the first phase-contrast micro-tomogram revealing quantitative electron density values of a biological sample using betatron X-rays, and a comprehensive source characterization. Our results suggest that laser-based X-ray technology offers the potential fo...
A 5 MeV betatron for calibration of radiation detectors
The design and fabrication of a 5 MeV betatron developed for calibration of radiation detectors at the Bhabha Atomic Research Centre, Bombay, is described. The magnet has been fabricated from 14 mil silicon steel laminations and weighs 225 kg. The field index is 0.75 and the radius of the equilibrium orbit is 5.6 cm. The betatron operates from 230 volts 50 cycles mains and requires about 2 KW of power. The electrons are injected from a heated thoriated tungsten filament by means of a high voltage (8KV) negative pulse. The pulse has approximately half sine wave shape having rise time of 1 μsec and duration 8 μsec. The electrons are accelerated to 5 MeV and produce X-rays on striing an internal tungsten target. The shifting of the electron orbit towards the target is effected by the saturation of the central core. The X-rays are emitted in the forward direction in a cone. The angle between the half intensity directions is 15 deg. The radiation output from the machine is equivalent to 50 mc of radium. (author)
Observation of Betatron radiation in the self-modulated regime of laser wakefield acceleration
Albert, Felicie; Pollock, Bradley; Goyon, Clement; Pak, Arthur; Moody, John; Shaw, Jessica; Lemos, Nuno; Marsh, Ken; Clayton, Christopher; Schumaker, William; Glenzer, Siegfried; Saunders, Alison; Falcone, Roger; Fiuza, Frederico; Joshi, Chan
2015-11-01
We observed multi keV Betatron x-rays from a self-modulated laser wakefield accelerator. The experiment was performed at the Jupiter Laser Facility, LLNL, by focusing the Titan short pulse beam (4-150 J, 1 ps) onto the edge of a Helium gas jet at electronic densities around 1019 cm-3. For the first time on this laser system, we used a long focal length optic, which produced a laser normalized potential a0 in the range 1-3. Under these conditions, electrons are accelerated by the plasma wave created in the wake of the light pulse. As a result, intense Raman satellites, which measured shifts depend on the electron plasma density, were observed on the laser spectrum transmitted through the target. Electrons with energies up to 200 MeV, as well as Betatron x-rays with critical energies around 20 keV, were measured. OSIRIS 2D PIC simulations confirm that the electrons gain energy both from the plasma wave and from their interaction with the laser field. This work was performed under the auspices of the U.S. Department of Energy under contract DE-AC52- 07NA27344, and supported by the Laboratory Directed Research and Development (LDRD) Program under tracking code 13-LW-076.
Crescenti, M
1998-01-01
The uniformity of a slow-extracted beam from a synchrotron is degraded by ripples from the power converters of the magnetic elements. This effect can be reduced by making the beam particles cross more quickly from the stable to the unstable region. Among the various methods that have been proposed for this purpose, RF bucket channelling seems to be a good candidate for compensating low frequency ripples in spills of the order of one second. The method is based on the technique of RF phase displacement acceleration. In the configuration studied, a coasting beam is accelerated slowly into a third-order resonance by a betatron core. The acceleration rate set by the betatron core determines the spill length. Empty buckets are then created at the resonance frequency and adjusted with a phase angle that would decelerate any trapped beam by an equal and opposite amount. The main RF system can be used for this purpose. The empty buckets cause an obstruction in phase space and the beam particles are forced to channel ...
Betatron motion with coupling of horizontal and vertical degrees of freedom
Lebedev, V.A.; /Fermilab; Bogacz, S.A.; /Jefferson Lab
2010-09-01
Presently, there are two most frequently used parameterizations of linear x-y coupled motion used in the accelerator physics. They are the Edwards-Teng and Mais-Ripken parameterizations. The article is devoted to an analysis of close relationship between the two representations, thus adding a clarity to their physical meaning. It also discusses the relationship between the eigen-vectors, the beta-functions, second order moments and the bilinear form representing the particle ellipsoid in the 4D phase space. Then, it consideres a further development of Mais-Ripken parameteresation where the particle motion is described by 10 parameters: four beta-functions, four alpha-functions and two betatron phase advances. In comparison with Edwards-Teng parameterization the chosen parametrization has an advantage that it works equally well for analysis of coupled betatron motion in circular accelerators and in transfer lines. Considered relationship between second order moments, eigen-vectors and beta-functions can be useful in interpreting tracking results and experimental data. As an example, the developed formalizm is applied to the FNAL electron cooler and Derbenev's vertex-to-plane adapter.
Yang Bing Xin; Guo, Weiming; Harkay, Katherine C; Sajaev, Vadim
2005-01-01
We present experimental studies of synchro-betatron-coupled electron beam motion in the Advanced Photon Source storage ring. We used a vertical kicker to start the beam motion. When the vertical chromaticity is nonzero, electrons with different initial synchrotron phases have slightly different betatron frequencies from the synchronous particle, resulting in a dramatic progression of bunch-shape distortion. Depending on the chromaticity and the time following the kick, images ranging from a simple vertical tilt in the bunch to more complicated twists and bends are seen with a visible light streak camera. Turn-by-turn beam position monitor data were taken as well. We found that the experimental observations are well described by the synchro-betatron-coupled equations of motion. We are investigating the potential of using the tilted bunch to generate picosecond x-ray pulses. Also note that the fast increase in vertical beam size after the kick is dominated by the internal synchro-betatron-coupled motion of the ...
Results from betatron phase measurements in RHIC during the sextant test
The Sextant Test of the Relativistic Heavy Ion Collider (RHIC) was an important step towards its completion. One sixth of the two RHIC accelerators was fully commissioned. gold ion beam was injected and transported through one sextant of one of the two rings. The betatron phase advance per cell was measured by recording differences in the horizontal and vertical positions of the beam at the end of the sextant due to a sequence of correction dipole kicks along the beam line. Measurement results show excellent agreement with predicted values, confirming that production measurements of the integral functions of the quadrupoles were very accurate, and that the polarity of all elements (correction dipoles, quadrupoles, dipoles etc.) was correct
Focusing system of the modified betatron: design, technology, manufacturing and test
In order to test the medium-energy electron cooling system based on modified betatron the design and construction of such a system prototype (MOBY) was started at JINR. Longitudinal magnetic field of 1 kG of the MOBY is provided by the solenoid system surrounded with a magnetic shielding of 8 mm thickness. The solenoids consist of several sections. The single-layer winding with six copper bars of the 'returning current' is placed inside the magnetic shielding. The bars are isolated and placed inside the slits in the magnetic shielding. The winding of each solenoid is made of copper pipe with the rectangular cross-section 18.5x18.5 mm. The design, the technology of solenoid manufacturing, and the method of the magnetic field measurements are presented
Positron Source from Betatron X-rays Emitted in a Plasma Wiggler
Johnson, D.K.; Clayton, C.E.; Huang, C.; Joshi, C.; Lu, W.; Marsh, K.A.; Mori, W.B.; Zhou, M.; /UCLA; Barnes, C.D.; Decker, F.J.; Hogan, M.J.; Iverson, R.H.; Krejcik, P.; O' Connell, C.L.; Siemann, R.; Walz, D.R.; /SLAC; Deng, S.; Katsouleas, T.C.; Muggli, P.; Oz, E.; /Southern California U.
2006-04-21
In the E-167 plasma wakefield accelerator (PWFA) experiments in the Final Focus Test Beam (FFTB) at the Stanford Linear Accelerator Center (SLAC), an ultra-short, 28.5 GeV electron beam field ionizes a neutral column of Lithium vapor. In the underdense regime, all plasma electrons are expelled creating an ion column. The beam electrons undergo multiple betatron oscillations leading to a large flux of broadband synchrotron radiation. With a plasma density of 3 x 10{sup 17}cm{sup -3}, the effective focusing gradient is near 9 MT/m with critical photon energies exceeding 50 MeV for on-axis radiation. A positron source is the initial application being explored for these X-rays, as photo-production of positrons eliminates many of the thermal stress and shock wave issues associated with traditional Bremsstrahlung sources. Photo-production of positrons has been well-studied; however, the brightness of plasma X-ray sources provides certain advantages. In this paper, we present results of the simulated radiation spectra for the E-167 experiments, and compute the expected positron yield.
A normal form approach to the theory of nonlinear betatronic motion
The betatronic motion of a particle in a circular accelerator is analysed using the transfer map description of the magnetic lattice. In the linear case the transfer matrix approach is shown to be equivalent to the Courant-Snyder theory: In the normal coordinates' representation the transfer matrix is a pure rotation. When the nonlinear effects due to the multipolar components of the magnetic field are taken into account, a similar procedure is used: a nonlinear change of coordinates provides a normal form representation of the map, which exhibits explicit symmetry properties depending on the absence or presence of resonance relations among the linear tunes. The use of normal forms is illustrated in the simplest but significant model of a cell with a sextupolar nonlinearity which is described by the quadratic Henon map. After recalling the basic theoretical results in Hamiltonian dynamics, we show how the normal forms describe the different topological structures of phase space such as KAM tori, chains of islands and chaotic regions; a critical comparison with the usual perturbation theory for Hamilton equations is given. The normal form theory is applied to compute the tune shift and deformation of the orbits for the lattices of the SPS and LHC accelerators, and scaling laws are obtained. Finally, the correction procedure of the multipolar errors of the LHC, based on the analytic minimization of the tune shift computed via the normal forms, is described and the results for a model of the LHC are presented. This application, relevant for the lattice design, focuses on the advantages of normal forms with respect to tracking when parametric dependences have to be explored. (orig.)
Neutron doses in an 8 MeV linear accelerator and an 18 MeV betatron
Using uranium fission track dosimeters, dose distributions of neutrons produced by photonuclear reaction in the shielding material were measured near an 8 MeV linear accelerator and an 18 MeV betatron. Dose equivalents, as a function of bremsstrahlung doses in the central beam, are given for different points outside the irradiation field, in particular at the location of the patient. The neutron production was determined as a function of photon energy between 8 and 18 MeV and compared with literature values. (orig./HP)
Behm, K. T.; Zhao, T. Z.; Cole, J. M.; Maksimchuk, A.; Mangles, S. P. D.; Nees, J.; Wood, J. C.; Yanovsky, V.; Krushelnick, K.; Thomas, A. G. R.
2016-05-01
Single photon counting techniques were used with an x-ray CCD camera to measure features of synchrotron-like x-ray spectra generated by betatron oscillations of electrons in a laser wakefield accelerator (LWFA) with different injection techniques. Measurements were made using the Hercules laser system at the University of Michigan. With a single stage gas cell, we demonstrate that pure helium gas in our wakefield accelerator will produce spectra with higher critical energies than when helium mixed with nitrogen is used. This result was not evident when a two stage gas cell was used.
Lari, L; Boccone, V; Brugger, M; Cerutti, F; Ferrari, A; Rossi, A; Versaci, R; Vlachoudis, V; Wollmann, D; Mereghetti, A; Faus-Golfe, A
2011-01-01
The Phase I LHC Collimation System Upgrade could include moving part of the Betatron Cleaning from LHC Point 7 to Point 3 to improve both operation flexibility and intensity reach. In addition, the partial relocation of beam losses from the current Betatron cleaning region at Point 7 will mitigate the risks of Single Event Upsets to equipment installed in adjacent and partly not sufficient shielded areas. The combined Betatron and Momentum Cleaning at Point 3 implies that new collimators have to be added as well as to implement a new collimator aperture layout. This paper shows the whole LHC Collimator Efficiency variation with the new layout at different beam energies. As part of the evaluation, energy deposition distribution in the IR3 region give indications about the effect of this new implementations not only on the collimators themselves but also on the other beam line elements as well as in the IR3 surrounding areas.
De Ninno, G
1999-07-01
The two parts of the thesis are a mission-oriented task devoted to solve some practical problems of the Antiproton Decelerator (AD) project at CERN, and a theoretical study leading to a new method for representing and compensating betatron resonances. The AD is a new machine (at the moment under commissioning at CERN) that will allow the collection and the deceleration of an antiproton beam from 3.5 GeV/c down to 100 MeV/c (the momentum favoured for the foreseen physics experiments). The need to employ the AD magnets over a wide range required a careful study of their characteristics. The presence of a solenoid inside the AD electron cooling device generates linear coupling between the transverse degrees of freedom of the single-particle motion. Coupling can lead to operational problems and therefore a compensation scheme had tobe designed. The long-standing problem has been solved of how to establish a relationship between the two standard methods for dealing with linear coupling: the matrix approach and the Hamiltonian approach. The bridge was built by including in the Hamiltonian approach in the high frequency part of the perturbative Hamiltonian due to coupling. The procedure was generalised to the nonlinear case and, a new method was proposed for dealing both with linear and nonlinear resonances. (author)
The two parts of the thesis are a mission-oriented task devoted to solve some practical problems of the Antiproton Decelerator (AD) project at CERN, and a theoretical study leading to a new method for representing and compensating betatron resonances. The AD is a new machine (at the moment under commissioning at CERN) that will allow the collection and the deceleration of an antiproton beam from 3.5 GeV/c down to 100 MeV/c (the momentum favoured for the foreseen physics experiments). The need to employ the AD magnets over a wide range required a careful study of their characteristics. The presence of a solenoid inside the AD electron cooling device generates linear coupling between the transverse degrees of freedom of the single-particle motion. Coupling can lead to operational problems and therefore a compensation scheme had to be designed. The long-standing problem has been solved of how to establish a relationship between the two standard methods for dealing with linear coupling: the matrix approach and the Hamiltonian approach. The bridge was built by including in the Hamiltonian approach in the high frequency part of the perturbative Hamiltonian due to coupling. The procedure was generalised to the nonlinear case and, a new method was proposed for dealing both with linear and nonlinear resonances. (author)
Upon the interaction of 60 TW Ti: sapphire laser pulses with 4 mm long supersonic nitrogen gas jet, a directional x-ray emission was generated along with the generation of stable quasi-monoenergetic electron beams having a peak energy of 130 MeV and a relative energy spread of ∼ 20%. The betatron x-ray emission had a small divergence of 7.5 mrad and a critical energy of 4 keV. The laser wakefield acceleration process was stimulated in a background plasma density of merely 5.4 × 1017 cm−3 utilizing ionization injection. The non-self-focusing and stable propagation of the laser pulse in the pure nitrogen gaseous plasma should be responsible for the simultaneous generation of the high-quality X-ray and electron beams. Those ultra-short and naturally-synchronized beams could be applicable to ultrafast pump-probe experiments
The results of experimental and calculational determination of coefficients for transition from readings of thermoluminescent detectors made of alumophosphate glass with manganese to absorbed dose in water for bremsstrahlung spectra generated at the voltage of 25 MV and 10-20 MeV electrons obtained in a betatron with electron beam sharping device are presented. Comparative measurements of absorbed dose have been obtained by means of ferrosulphate chemical system and two dosemeters with ionization chambers. Measurements have been conducted in water phantom. It is shown that the absorbed dose total measuring error does not exceed +-10% for 95% confidence interval. The obtained relations for calculation of coefficients for transition to absorbed dose and physical characteristics of thermoluminescent detectors can be used to forecast their behaviour in high-energy bremsstrahlung fields with arbitrary spectra as well as for determination of electron spectra with energy up to 25 MeV. It is established that for electrons with average energy of 10 and 20 MeV the dependence of the detector readings on the phantom depth does not exceed +-2% at depths from zero to 90% of electron range
Exposures of the eyes of patients and phantoms to fast electrons from a 17 MeV betatron have been measured during the irradiation of tumours in the head and cervical region. In irradiating the region below the oral plane or behind the auditory passage the crystalline lenses receive less than 0.5% of the tumour dose even in the most unfavourable cases. Irradiation of the region above the oral plane and before the auditory passage, except the region close to the eyes, causes a maximum dose to the crystalline lenses of 3% of the tumour dose, whereas during irradiation in direct proximity to the eyes between 5 and 15% of the tumour dose have been measured. (author)
A dose of 4 MeV, Betatron electronic rays, 600 rad and 1200 rad were applied to the 3rd primary molar and the 4th permanent premolar germ, respectively in the right mandibles of 58 young (3 mo.) dogs. In both irradiated groups disturbance of enamel formation was observed on and after the 21st day after irradiation. After the 21st day pulp cells around the cervical end of the dentin were arranged radially, meeting at right angles with collagenous fibers developing within immature pulp tissue. In the 1200 rad group, destruction of Hertwig's epithelial sheath was observed on the 14th day, and on the 30th day the sheath disappeared. About that time, osteoblast-like cells different from odontoblast appeared, and osteodentin began to form. In the 600 rad group, little trouble in dentin and pulp tissues was observed, and only hypoplasia of the enamel was noticed. These observation suggested that the radiosensitivity of the ameloblasts derived from the ectoderm was higher than the other. In the 1200 rad dose group, enamel hypoplasia, osteodentin formation, reticular atrophy of pulp and shortening of tooth root were found. These findings were not so different from results of predecessors in experiments with over 1000 R. In both the 600 and 1200 rad dose groups growth of the permanent tooth showed remarkably delay and severe crowding within the mendible. In the primary tooth, there was slight pulp congestion and a decreased number of pulp cells. In the 600 rad dose group, the mandible was unaffected, but in the 1200 rad group there was congestion of bone marrow, fibrous degeneration of bone tissue and so on. (Evans, J.)
Starting from the Lagrangian of a charged particle in an electromagnetic field, the Hamiltonian for non-linear coupled synchro-betatron oscillations of ultra-relativistic charged particles (protons) is derived. The canonical variables are x, psub(x), z, psub(z), sigma, eta which are well-known from the six dimensional linear theory (SLIM). Keeping only terms up to second order in the canonical momenta psub(x), psub(z), the equations of motion are then solved for various kinds of magnets (quadrupole, skew quadrupole, bending magnet, synchrotron-magnet, solenoid, sextupole, octupole, dipole kicker) and for cavities, taking into account the effect of energy deviation on the focusing strength. The equations so derived can serve to develop a non-linear, six dimensional (symplectic) tracking program for ultra-relativistic protons. (orig.)
Stabilization of betatron tune in Indus-2
Jena, Saroj; Yadav, S.; R. K. Agrawal; Ghodke, A. D.; Fatnani, Pravin; Puntambekar, T. A.
2013-01-01
Indus-2 is a synchrotron radiation source which is operational at RRCAT, Indore; India. It is essentially pertinent in any synchrotron radiation facility to store the electron beam without beam loss. During the day to day operation of Indus-2 storage ring difficulty was being faced in accumulating higher beam current. After examining, it was found that the working point was shifting from its desired value during accumulation. For smooth beam accumulation, a fixed desired tune in both horizont...
On electron betatron motion and electron injection in laser wakefield accelerators
Matsuoka, T.; McGuffey, C.; Cummings, P.G.; Bulanov, S.S.; Chvykov, V.; Dollar, F.; Horovitz, Y.; Kalinchenko, Galina; Krushelnick, K.; Rousseau, P.; Thomas, A.G.R.; Yanovsky, V.; Maksimchuk, A.
2015-01-01
Roč. 56, č. 8 (2015), s. 1-8. ISSN 0741-3335 Institutional support: RVO:68378271 Keywords : accelerators * beams and electromagnetism * nuclear physics * plasma physics Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.186, year: 2014
High-resolution and ultrafast imaging using betatron x-rays from laser wakefield accelerators
Najmudin, Zulfikar
2015-11-01
Laser wakefield accelerators now routinely produce ~GeV energy gain in ~cm plasmas. and are simultaneously capable of producing high brightness and spatially coherent hard x-ray beams. This unique light-source has been used for medical applications, and also for ultrafast imaging in high energy density science. The experiments were performed with the Astra Gemini laser producing 10 J pulses with duration ~ 40 fs focussed to produce a spot of 25 μ m (fwhm) in a gas-cell of variable length to produce a low divergence beam of x-rays. The length of the gas cell was optimised to produce high contrast x-ray images of radiographed test objects. This source was used for full tomographic imaging of a human trabecular bone sample, with resolution exceeding the ~ 100 μ m level required for CT applications. Phase-contrast imaging of human prostate and mouse neonates at the micron level was also demonstrated. These studies indicate the usefulness of these sources in research and clinical applications. The ultrafast nature of the source was also demonstrated by performing time resolved imaging of a laser driven shock. The ultrashort duration of the x-ray source essentially freeze the motion of these fast moving transient phenomena.
Computation of betatron mismatch and emmitance blow-up for multi-turn extraction
Cappi, R
2002-01-01
The present version of the five-turn Continuous Transfer extraction at PS machine is based on beam slicing by means of an electrostatic septum. Recently, a novel approach has been proposed, where the beam is split into five beamlets by means of stable islands, created by sextupoles and octupoles, together with a proper tune variation. In this paper, the two approaches are compared by considering their properties in terms of equivalent optical parameters, beam emittance, and emittance after filamentation in the receiving machine (SPS) for the various slices. Analytic expressions of the relevant optical and beam parameters are derived for the present version of the Continuous Transfer, while the same quantities are estimated in the case of the novel approach via numerical simulations. Finally, the robustness of the approach based on adiabatic capture in transverse phase space is discussed with particular emphasis on tune ripple effects and variation of nonlinear elements strength.
Observation of Spontaneous Emitted X-ray Betatron Radiation in Beam-Plasma Interactions
An experiment is being carried out at the Stanford Linear Accelerator Center (SLAC) to see if an ion channel can wiggle a beam of ultra-relativistic electrons to produce x-ray radiation. The goal is to create an intense source of undulator radiation using a plasma wiggler in the 1-10 KeV range and also to determine the suitability of such an electrostatic wiggler to create a coherent beam of x-rays via the ion channel laser mechanism [1]. Here we give some of the scaling laws for the power and frequency distribution of the spontaneous emission from sending an electron beam through such an ion channel. Some initial experimental observations are also presented
Addenda to General Spin Precession and Betatron Oscillation in Storage Ring
Fukuyama, Takeshi
2016-01-01
We give the geralized expression of spin precession of extended bunch particles having both anomalous magnetic and electric dipole moments in storage ring in higher order than the previous work and in the presence of ${\\bf E}$ field as well as ${\\bf B}$ field. These addenda are essential since some experiments consider the focusing field in the second order of the beam extent and in the presence of both ${\\bf B}$ and ${\\bf E}$ fields . It is shown that some focusing fields with constant magnitude of the velocity considered in many literatures lead to the violation of self consistency.
Effect of experimental laser imperfections on laser wakefield acceleration and betatron source
Ferri, J.; Davoine, X.; Fourmaux, S.; Kieffer, J. C.; Corde, S.; Ta Phuoc, K.; Lifschitz, A.
2016-01-01
Laser pulses in current ultra-short TW systems are far from being ideal Gaussian beams. The influence of the presence of non-Gaussian features of the laser pulse is investigated here from experiments and 3D Particle-in-Cell simulations. Both the experimental intensity distribution and wavefront are used as input in the simulations. It is shown that a quantitative agreement between experimental data and simulations requires to use realistic pulse features. Moreover, some trends found in the experiments, such as the growing of the X-ray signal with the plasma length, can only be retrieved in simulations with realistic pulses. The performances on the electron acceleration and the synchrotron X-ray emission are strongly degraded by these non-Gaussian features, even keeping constant the total laser energy. A drop on the X-ray photon number by one order of magnitude was found. This clearly put forward the limitation of using a Gaussian beam in the simulations. PMID:27324915
In this paper the authors study the on- momentum nonlinear equations of motion for the coupled transverse motion of a single charged particle in a storage ring. The authors seek for the maximum initial linear amplitudes in the two transverse directions x and y which lead to bounded particle motion as t tends to infinity. Although the authors restrict themselves to sextupole fields in this paper, the authors may easily extend the method to any order multipole. The aim of this work is to derive an analytic approximate expression for the dynamical aperture. The authors approach the solutions of x and y by use of a classical secular perturbation theory. Every coefficient of the perturbation series can be expressed as an analytic function of all the lower order coefficients. Although perturbation theory if it is evaluated to certain specific order leads only to an approximation in terms of bounded (trigonometric) functions the authors may derive information about the stability limit by considering the convergency radius of the general perturbation. This is done in the present paper by deriving an approximate analytic expression for the n-th order perturbation contribution of the whole series using only results up to second order. The actual calculations have been performed for the fully two dimensional case but for simplicity the authors shall explain only the one dimensional case of the pure horizontal motion
Quantitative X-ray phase-contrast microtomography from a compact laser-driven betatron source
Wenz, J; S. Schleede; Khrennikov, K.; Bech, M.; Thibault, P.; Heigoldt, M.; Pfeiffer, F.; Karsch, S.
2015-01-01
X-ray phase-contrast imaging has recently led to a revolution in resolving power and tissue contrast in biomedical imaging, microscopy and materials science. The necessary high spatial coherence is currently provided by either large-scale synchrotron facilities with limited beamtime access or by microfocus X-ray tubes with rather limited flux. X-rays radiated by relativistic electrons driven by well-controlled high-power lasers offer a promising route to a proliferation of this powerful imagi...
Xu, Wei; Z. Wu, W.; Li, Jing-Yi; He, Duo-Hui; K. Wu, Y.
2013-07-01
To combat electron beam instabilities, a digital bunch-by-bunch transverse feedback (TFB) system has been developed for the Duke storage ring. While it is capable of suppressing transverse beam instabilities for multibunch operation, the TFB system has not been needed for typical operation of the Duke storage ring. To explore the great potential of this system, we have developed beam diagnostic techniques using the TFB, in particular, the TFB based tune measurement techniques. The tune measurement technique allows us to conduct fast chromaticity measurements, compared with the existing chromaticity measurement system using a network analyzer. This new tune measurement system also enables us to measure the bunch tune for multibunch operation of the Duke storage ring. With the TFB based tune measurement system, we have studied the tune stability of the electron beam in the Duke storage ring. This tune system has also been used to calibrate the tune knob for the Duke storage ring.
Ribière, M.; Sebban, Stéphane; Jacquemot, S.; Chéron, B.G.; Ta Phuoc, K.; Gautier, J.; Grunenwald, J.; Ribeiro, P.; Kozlová, Michaela; Zeitoun, P.; Rousse, A.
2012-01-01
Roč. 106, č. 4 (2012), s. 809-816. ISSN 0946-2171 R&D Projects: GA MŠk ED1.1.00/02.0061 Grant ostatní: ELI Beamlines(XE) CZ.1.05/1.1.00/02.0061 Institutional support: RVO:68378271 Keywords : x-ray laser Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.782, year: 2012
Gouiran, R
1978-01-01
Precise control of the quadrupole and sextupole components of the magnetic fields in focusing and defocusing sectors respectively was achieved by the combined use of pole-face and yoke windings with three separate power supplies synchronously programmed by a computer. Experience of this technique led to a new philosophy in the design of pole-face windings, in which they become an integral and active part of the magnet. With the arrangement described, focusing and guiding functions are partially separated and an old combined-function accelerator can be transformed effectively into a more flexible separate-function machine without any decrease in available straight- section space. (5 refs).
Rossi, V
2002-01-01
In the framework of the LHC project and the modifications of the SPS as its injector, I present the concept of global digital signal processing applied to a particle accelerator, using Field Programmable Gate Array (FPGA) technology. The approach of global digital synthesis implements in numerical form the architecture of a system, from the start up of a project and the very beginning of the signal flow. It takes into account both the known parameters and the future evolution, whenever possible. Due to the increased performance requirements of today's projects, the CAE design methodology becomes more and more necessary to handle successfully the added complexity and speed of modern electronic circuits. Simulation is performed both for behavioural analysis, to ensure conformity to functional requirements, and for time signal analysis (speed requirements). The digital notch filter with programmable delay for the SPS Transverse Damper is now fully operational with fixed target and LHC-type beams circulating in t...
Ju, Jinchuan
2013-01-01
Cette thèse porte sur le rayonnement X bêtatron généré par des électrons accélérés par sillage laser plasma dans des tubes capillaires diélectriques. En l’état actuel de la technologie des impulsions laser multi-térawatts, on peut produire des faisceaux ayant une intensité crête élevée, de l’ordre de 1018 W/cm2 dans le plan focal. Une telle impulsion laser se propageant au sein d’un gaz sous-dense conduit à des phénomènes d’interaction laser-plasma non-linéaires, tels que la création d’une bu...
Observation and analysis of oscillations in linear accelerators
This report discusses the following on oscillation in linear accelerators: Betatron Oscillations; Betatron Oscillations at High Currents; Transverse Profile Oscillations; Transverse Profile Oscillations at High Currents.; Oscillation and Profile Transient Jitter; and Feedback on Transverse Oscillations
Universal stability diagrams have been calculated and experimentally checked for Hill-Meissner type equations with square-wave coefficients. The study of these equations in the phase-plane has then made it possible to extend the periodic solution calculations to the case of non-linear differential equations with periodic square-wave coefficients. This theory has been checked experimentally. For non-linear coupled systems with constant coefficients, a search was first made for solutions giving an algebraic motion. The elliptical and Fuchs's functions solve such motions. The study of non-algebraic motions is more delicate, apart from the study of nonlinear Lissajous's motions. A functional analysis shows that it is possible however in certain cases to decouple the system and to find general solutions. For non-linear coupled systems with periodic square-wave coefficients it is then possible to calculate the conditions leading to periodic solutions, if the two non-linear associated systems with constant coefficients fall into one of the categories of the above paragraph. (author)
Tomsk polytechnical institute induction accelerators used in industry, medicine and applied studies
Three types of betatrons have been developed: (1) small-size mobile, (2) stationary, and (3) high-current at energies of up to 50 MeV. Structurally all the betatrons consist of a radiator, a supply unit, and a control panel. Small-size betatrons, type MIB-3, allow manual transportation and can be used for monitoring purposes in regions difficult for access. Overall dimensions of the B18 mobile betatron permit its location in a truck body. Betatrons of the B-25/10 type are stationary plants. A possibility of the wide radiation energy control permits the selection of optimum conditions of radioscopy in a wide range of thicknesses of checked articles. The developed circuits meant for synchronizing the betatron radiation pulse with the moving parts make it possible to check the exactness of assembling. Basing on betatrons used in the defectoscopy several versions of medical betatrons have been developed. A rotation mechanism incorporated into these betatrons allows irradiation of patient's internals without great injures to surface and surrounding tissues
Fundamentals of particle beam dynamics and phase space
This report discusses the following topics on synchrotron accelerators: Transverse motion---betatron oscillations; machine lattice; representation of a particle beam; and longitudinal motion---synchrotron oscillations
Valat, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires
1960-12-15
Universal stability diagrams have been calculated and experimentally checked for Hill-Meissner type equations with square-wave coefficients. The study of these equations in the phase-plane has then made it possible to extend the periodic solution calculations to the case of non-linear differential equations with periodic square-wave coefficients. This theory has been checked experimentally. For non-linear coupled systems with constant coefficients, a search was first made for solutions giving an algebraic motion. The elliptical and Fuchs's functions solve such motions. The study of non-algebraic motions is more delicate, apart from the study of nonlinear Lissajous's motions. A functional analysis shows that it is possible however in certain cases to decouple the system and to find general solutions. For non-linear coupled systems with periodic square-wave coefficients it is then possible to calculate the conditions leading to periodic solutions, if the two non-linear associated systems with constant coefficients fall into one of the categories of the above paragraph. (author) [French] Pour les equations du genre de Hill-Meissner a coefficients creneles, on a calcule des diagrammes universels de stabilite et ceux-ci ont ete verifies experimentalement. L'etude de ces equations dans le plan de phase a permis ensuite d'etendre le calcul des solutions periodiques au cas des equations differentielles non lineaires a coefficients periodiques creneles. Cette theorie a ete verifiee experimentalement. Pour Jes systemes couples non lineaires a coefficients constants, on a d'abord cherche les solutions menant a des mouvements algebriques. Les fonctions elliptiques et fuchsiennes uniformisent de tels mouvements. L'etude de mouvements non algebriques est plus delicate, a part l'etude des mouvements de Lissajous non lineaires. Une analyse fonctionnelle montre qu'il est toutefois possible dans certains cas de decoupler le systeme et de trouver des solutions generales. Pour les systemes couples non lineaires a coefficients periodiques creneles, il est alors possible de calculer les conditions menant a des solutions periodiques, si les deux systemes non lineaires adjoints a coefficients constants, entrent dans une des categories du paragraphe precedent. (auteur)
Higher order multipole magnet tolerances
Due to field impurities in the magnets in a storage ring or circular accelerator the values of the betatron frequencies for a given particle in a beam are dependent upon the energy and betatron amplitude of the particle as well as the values of the energy dispersion and betatron functions at the magnets. A method has been developed for finding the values of the betatron frequencies for any particle with given field impurities. This method has been used to study the quality of several preliminary designs of some of the quadrupole magnets in PEP by comparing the variations of the betatron frequencies over the maximum expected range of values of the particle energy and betatron amplitude. The expressions for the values of betatron frequencies as functions of the various beam and machine parameters are derived. Some of the results for the evaluation of two types of the PEP magnets are also presented. A discussion of these results is given as well. 3 refs., 5 figs., 2 tabs
Nonparaxial propagation of ultrashort laser pulses in plasma channels
The propagation characteristics of an ultrashort laser pulse in a preformed plasma channel are analyzed. The plasma channel is assumed to be parabolic and unperturbed by the laser pulse. Solutions to the wave equation beyond the paraxial approximation are derived that include finite pulse length effects and group velocity dispersion. When the laser pulse is mismatched within the channel, betatron oscillations arise in the laser pulse envelope. A finite pulse length leads to a spread in the laser wave number and consequently a spread in betatron wave number. This results in phase mixing and damping of the betatron oscillation. The damping distance characterizing the phase mixing of the betatron oscillation is derived, as is the dispersion distance characterizing the longitudinal spreading of the pulse. copyright 1999 The American Physical Society
Suppression of bunch transverse instabilities by the chamber asymmetry
Axial asymmetry of a vacuum chamber gives rise to wake forces producing betatron tune shifts for tail particles. In the result, the bunch transverse instabilities could be suppressed or even eliminated
Coupling measurement and correction at the SSRF storage ring
无
2011-01-01
Brightness is an important parameter for 3rd generation light source. Correcting the emittance coupling is a realistic way to increase brightness without any additional equipment in a machine under operation. The main sources of emittance coupling are betatron coupling and vertical dispersion. At the SSRF storage ring, tune split and LOCO are used to measure the respective betatron and emittance coupling. Both of these sources can be corrected by skew quadrupoles. By measuring the skew quadrupole-coupling response matrix, betatron coupling can be changed from 0.014% to 2%. But the vertical dispersion changes at the same time. LOCO can find the suitable setting to correct simultaneously the betatron coupling and vertical dispersion. The emittance coupling can be reduced to 0.17% by this method. More simulations show the potential for smaller emittance coupling if more skew quadrupoles are employed.
Incoherent beam-beam effect---The relationship between tune-shift, bunch length and dynamic aperture
Simulation studies of the influence of long bunches on the beam-beam effect in particle colliders suggest that, despite the risk from synchro-betatron resonances, the attainable luminosity may be greater than that obtained for short bunches
Resonances and resonance widths
Two-dimensional betatron resonances are much more important than their simple one-dimensional counterparts and exhibit a strong dependence on the betatron phase advance per cell. A practical definition of ''width'' is expanded upon in order to display these relations in tables. A primarily pedagogical introduction is given to explain the tables, and also to encourage a wider capability for deriving resonance behavior and wider use of ''designer'' resonances
Oscillatory Response of a Beam to a Transverse Kick
1974-01-01
When a circulating beam receives a transverse kick, it begins to perform coherent betatron oscillations. Their amplitude depends on strength, length and temporal shape of the kick, and on the Q-value (betatron tune) of the accelerator or storage ring. A calculation of a response function is shown in 3-dimensional presentation with the means of 1974: graph paper glued on cardboard stuck in a slotted base-plate.
THE ANALYSIS OF DEPOLARIZATION FACTORS IN THE LAST RHIC RUN
Polarized proton beams were accelerated successfully at RHIC up to 100 Gev with the use of Siberian Snakes. Although the snakes were designed to preserve polarization, the successful acceleration and storage of polarized beams was dependent also on beam characteristics, like closed orbit, betatron tunes and even betatron coupling. The high-order spin resonances were observed and evaluated. The paper summarizes depolarizing effects observed during the run
The application of thermoluminescent dosimetry for the development of new irradiation procedures is reported. Of particular interest are some subjets as betatron dosimetry, surface radiation loading in the case of electron irradiation, X-ray contamination of electron beams, and background radiation in the vicinity of a betatron. Methodical aspects for the optimization of Co-60 gamma radiation therapy are of special importance for the treatment of mammary cancer glands. (DG)
The tune meter systems at the AGS complex
A measurement system of the betatron tune is operational at the AGS and one for the AGS Booster is under development. Both systems use ferrite kicker magnets to excite coherent betatron oscillations. Difference signals are samples at the revolution frequency and the tune is extracted from a Fast Fourier Transform. Details of the hardware of both system will be described, as well as all the features of the application program through which the operator interacts with the hardware. 10 refs., 4 figs
Programmable high power beam damper for the Tevatron
A bunch-by-bunch beam damper has been developed for the Fermilab Tevatron. The system reduces betatron oscillation amplitudes and incorporates some useful machine diagnostics. The device is programmable via look-up tables so the output is an arbitrary function, on a bunch-by-bunch basis, of the beam displacement. We are presently using this feature to measure the betatron tune throughout the acceleration cycle. 4 refs
Software for online tune measurement system for Indus - 2 accelerator
Indus-2 is an electron storage ring designed for the beam energy of 2.5 GeV and 300 mA beam current. Betatron tune is an important parameter for an accelerator. A particle displaced transversely from its equilibrium orbit executes betatron oscillations about the orbit. The number of periods of oscillation in one complete turn around the machine is called betatron tune (Q). A tune measurement system has been developed for measurement of fractional part of tune of the INDUS-2 accelerator. Betatron tune is measured by applying a transverse excitation to the beam using a continuous RF source or pulsed magnet. This causes the beam to execute coherent betatron oscillations. A beam position monitor is used to measure the resulting beam response. The beam response is analyzed in frequency domain for tune measurement. Frequency domain analysis is performed either using spectrum analyzer or by taking the FFT of time domain beam response. This paper describes the software development to perform the FFT of beam response signal and calculate the tune. Software has been tested successfully and is being planned to be used for tune measurement in Indus-2. (author)
Model-independent analysis of the Fermilab Tevatron turn-by-turn beam position monitor measurements
Petrenko, A.V.; /Novosibirsk, IYF; Valishev, A.A.; Lebedev, V.A.; /Fermilab
2011-09-01
Coherent transverse beam oscillations in the Tevatron were analyzed with the model-independent analysis (MIA) technique. This allowed one to obtain the model-independent values of coupled betatron amplitudes, phase advances, and dispersion function around the ring from a single dipole kick measurement. In order to solve the MIA mode mixing problem which limits the accuracy of determination of the optical functions, we have developed a new technique of rotational MIA mode untangling. The basic idea is to treat each beam position monitor (BPM) as two BPMs separated in a ring by exactly one turn. This leads to a simple criterion of MIA mode separation: the betatron phase advance between any BPM and its counterpart shifted by one turn should be equal to the betatron tune and therefore should not depend on the BPM position in the ring. Furthermore, we describe a MIA-based technique to locate vibrating magnets in a storage ring.
RHIC Spin Flipper Commissioning Status
Bai, M.; Meot, F.; Dawson, C.; Oddo, P.; Pai, C.; Pile, P.; Makdisi, Y.; Meng, W.; Roser, T.
2010-05-23
The commissioning of the RHIC spin flipper in the RHIC Blue ring during the RHIC polarized proton run in 2009 showed the detrimental effects of global vertical coherent betatron oscillation induced by the 2-AC dipole plus 4-DC dipole configuration. This global orbital coherent oscillation of the RHIC beam in the Blue ring in the presence of collision modulated the beam-beam interaction between the two RHIC beams and affected Yellow beam polarization. The experimental data at injection with different spin tunes by changing the snake current also demonstrated that it was not possible to induce a single isolated spin resonance with the global vertical coherent betatron oscillation excited by the two AC dipoles. Hence, a new design was proposed to eliminate the coherent vertical betatron oscillation outside the spin flipper by adding three additional AC dipoles. This paper presents the experimental results as well as the new design.
GLOBAL DECOUPLING ON THE RHIC RAMP.
LUO, Y.; CAMERON, P.; DELLA PENNA, A.; FISCHER, W.; ET AL.
2005-05-16
The global betatron decoupling on the ramp is an important issue for the operation of the Relativistic Heavy Ion Collider (RHIC), especially in the RHIC polarized proton (pp) run. To avoid the major betatron and spin resonances on the ramp, the betatron tunes are constrained. And the rms value of the vertical closed orbit should be smaller than 0.5mm. Both require the global coupling on the ramp to be well corrected. Several ramp decoupling schemes were found and tested at RHIC, like N-turn map decoupling, three-ramp correction, coupling amplitude modulation, and coupling phase modulation. In this article, the principles of these methods are shortly reviewed and compared. Among them, coupling angle modulation is a robust and fast one. It has been applied to the global decoupling in the routine RHIC operation.
Relativistic Heavy Ion Collider spin flipper commissioning plan
Bai, M.; Dawson, C.; Makdisi, Y.; Meng, W.; Meot, F.; Oddo, P.; Pai, C.; Pile, P.; Roser, T.
2010-09-27
The commissioning of the RHIC spin flipper in the RHIC Blue ring during the RHIC polarized proton run in 2009 showed the detrimental effects of global vertical coherent betatron oscillation induced by the 2-AC dipole plus 4-DC dipole configuration. This global orbital coherent oscillation of the RHIC beam in the Blue ring in the presence of collision modulated the beam-beam interaction between the two RHIC beams and affected Yellow beam lifetime. The experimental data at injection with different spin tunes by changing the snake current also demonstrated that it was not possible to induce a single isolated spin resonance with the global vertical coherent betatron oscillation excited by the two AC dipoles. Hence, RHIC spin flipper was re-designed to eliminate the coherent vertical betatron oscillation outside the spin flipper by adding three additional AC dipoles. This paper presents the experimental results as well as the new design.
High precision tune and coupling measurements and tune/coupling feedback in RHIC
Minty, M.; Curcio, A.; Dawson, C.; Degen, C.; Luo, Y.; Marr, G.; Martin, B.; Marusic, A.; Mernick, K.; Oddo, P.; Russo, T.; Schoefer, V.; Schroeder, R.; Schulthiess, C.; Wilinski, M.
2010-08-01
Precision measurement and control of the betatron tunes and betatron coupling in RHIC are required for establishing and maintaining both good operating conditions and, particularly during the ramp to high beam energies, high proton beam polarization. While the proof-of-principle for simultaneous tune and coupling feedback was successfully demonstrated earlier, routine application of these systems has only become possible recently. Following numerous modifications for improved measurement resolution and feedback control, the time required to establish full-energy beams with the betatron tunes and coupling regulated by feedback was reduced from several weeks to a few hours. A summary of these improvements, select measurements benefitting from the improved resolution and a review of system performance are the subject of this report.
Theoretical aspects of some collective instabilities in high-energy particle storage rings
After an introduction to single-particle dynamics, based on a unified Hamiltonian treatment of betatron and synchrotron oscillations, we consider two examples of collective instabilities which can limit the performances of high-energy storage rings: the transverse mode coupling instability, due to wake fields, and the incoherent beam-beam instability. Special emphasis is placed on the localization of the interactions between particles and surrounding structures, such as the accelerating RF cavities. We derive an exact invariant for the linearized synchrotron motion and, starting from the Vlasov equation, we discuss the coherent synchro-betatron resonances caused by localized impedance. Under suitable assumptions, we show that the effect of the beam-beam kicks in electron-positron machines can be described by new diffusive terms in a ''renormalized'' Fokker-Planck equation and is therefore equivalent to an additional source of noise for the betatron oscillations. (orig.)
Compensation of the linear effect of insertion devices for the storage ring INDUS-2
A method to correct the distortion of betatron functions and linear tunes caused by insertion devices is discussed. In this method the strengths of several quadrupole magnets are varied such that the tunes are fully corrected and distortions of betatron functions are minimised. Based on this method a computer code name BURHANI has ben developed and used for simulating the effect of wigglers and undulators in the storage ring INDUS-2, a 2.5 GeV synchrotron radiation source, under construction at the Centre for Advanced Technology. The results of the simulation studies for INDUS-2 are presented
Classical and modern power spectrum estimation for tune measurement in CSNS RCS
Precise measurement of betatron tune is required for good operating condition of CSNS RCS. The fractional part of betatron tune is important and it can be measured by analyzing the signals of beam position from the appointed BPM. Usually these signals are contaminated during the acquisition process, therefore several power spectrum methods are used to improve the frequency resolution. In this article classical and modern power spectrum methods are used. In order to compare their performance, the results of simulation data and IQT data from J-PARC RCS are discussed. It is shown that modern power spectrum estimation has better performance than the classical ones, though the calculation is more complex. (authors)
Measurement of parameters in Indus-2 synchrotron radiation source
Ghodke, A. D.; Husain, Riyasat; Kumar, Pradeep; Yadav, Surendra; Puntambekar, T. A. [Raja Ramanna Centre for Advanced Technology, 452013, Indore (India)
2012-10-15
The paper presents the measurement of optics parameters in Indus-2 synchrotron radiation source, which include betatron tune, beta function, dispersion function, natural chromaticity, corrected chromaticity, central RF frequency, momentum compaction factor, and linear betatron coupling. Two methods were used for beta function measurement; a conventional quadrupole scan method and a method using the fitting of the orbit response matrix. A robust Levenberg-Marquardt algorithm was used for nonlinear least square fitting of the orbit response matrix. In this paper, detailed methods for the parameter measurements are described. The measured results are discussed and compared with the theoretical values obtained using accelerator simulation code Accelerator Toolbox in MATLAB.
Classical and modern power spectrum estimation for tune measurement in CSNS RCS
Yang, Xiaoyu; Fu, Shinian; Zeng, Lei; Bian, Xiaojuan
2013-01-01
Precise measurement of betatron tune is required for good operating condition of CSNS RCS. The fractional part of betatron tune is important and it can be measured by analyzing the signals of beam position from the appointed BPM. Usually these signals are contaminated during the acquisition process, therefore several power spectrum methods are used to improve the frequency resolution. In this article classical and modern power spectrum methods are used. In order to compare their performance, the results of simulation data and IQT data from J-PARC RCS are discussed. It is shown that modern power spectrum estimation has better performance than the classical ones, though the calculation is more complex.
Yang, Xi
2015-01-01
We propose a method to simultaneously correct linear optics errors and linear coupling for storage rings using turn-by-turn (TbT) beam position monitor (BPM) data. The independent component analysis (ICA) method is used to isolate the betatron normal modes from the measured TbT BPM data. The betatron amplitudes and phase advances of the projections of the normal modes on the horizontal and vertical planes are then extracted, which, combined with dispersion measurement, are used to fit the lattice model. The fitting results are used for lattice correction. The method has been successfully demonstrated on the NSLS-II storage ring.
Yang, Xi; Huang, Xiaobiao
2016-08-01
We propose a method to simultaneously correct linear optics errors and linear coupling for storage rings using turn-by-turn (TbT) beam position monitor (BPM) data. The independent component analysis (ICA) method is used to isolate the betatron normal modes from the measured TbT BPM data. The betatron amplitudes and phase advances of the projections of the normal modes on the horizontal and vertical planes are then extracted, which, combined with dispersion measurement, are used to fit the lattice model. The fitting results are used for lattice correction. The method has been successfully demonstrated on the NSLS-II storage ring.
Measurement and correction of accelerator optics
This report reviews procedures and techniques for measuring, correcting and controlling various optics parameters of an accelerator, including the betatron tune, beta function, betatron coupling, dispersion, chromaticity, momentum compaction factor, and beam orbit. The techniques described are not only indispensable for the basic set-up of an accelerator, but in addition the same methods can be used to study more esoteric questions as, for instance, dynamic aperture limitations or wakefield effects. The different procedures are illustrated by examples from several accelerators, storage rings, as well as linacs and transport lines
Kolski, Jeffrey S. [Los Alamos National Laboratory; Macek, Robert J. [Los Alamos National Laboratory; McCrady, Rodney C. [Los Alamos National Laboratory; Pang, Xiaoying [Los Alamos National Laboratory
2012-05-14
Independent component analysis (ICA) is a powerful blind source separation (BSS) method. Compared to the typical BSS method, principal component analysis (PCA), which is the BSS foundation of the well known model independent analysis (MIA), ICA is more robust to noise, coupling, and nonlinearity. ICA of turn-by-turn beam position data has been used to measure the transverse betatron phase and amplitude functions, dispersion function, linear coupling, sextupole strength, and nonlinear beam dynamics. We apply ICA in a new way to slices along the bunch and discuss the source signals identified as betatron motion and longitudinal beam structure.
Acceleration region influence on beam parameters on stripping foil
Some formulas describing the beam parameters on the stripping foil (SF) as a function of the radial amplitude of betatron oscillations and energy gain are derived. The results computed by these formulas are in good agreement with the results of the numerical calculations. Obtained results show that between the radial emittance and the energy spread exists parametric dependence via amplitude of radial betatron oscillations. This conclusion allows one to create a working diagram of expected beam parameters on SF. This diagram may be particularly useful for the extraction system designers since it gives relationship between parameters considered as the extraction system input parameters. (author)
High level software for 4.8 GHz LHC Schottky system
Cai, J; Pasquinelli, R; Favier, M; Jones, O R; Lahey, T; Jansson, A
2011-01-01
The performance of the LHC depends critically on the accurate measurements of the betatron tunes. The betatron tune values of each LHC beam may be measured without excitation using a newly installed transverse Schottky monitor. A high-level software package written in Java has been developed for the Schottky system. The software allows end users to monitor and control the Schottky system, and provides them with non-destructive and continuous bunch-by-bunch measurements for the tunes, momentum spreads, chromaticities and emittances of the LHC beams. It has been tested with both proton and lead ion beams at the LHC with very successful results.
Double layer -- a particle accelerator in the magnetosphere
Fu, Xiangrong [Los Alamos National Laboratory
2015-07-16
Slides present the material under the following topics: Introduction (What is a double layer (DL)? Why is it important? Key unsolved problems); Theory -- time-independent solutions of 1D Vlasov--Poisson system; Particle-in-cell simulations (Current-driven DLs); and Electron acceleration by DL (Betatron acceleration). Key problems include the generation mechanism, stability, and electron acceleration. In summary, recent observations by Van Allen Probes show large number of DLs in the outer radiation belt, associated with enhanced flux of relativistic electrons. Simulations show that ion acoustic double layers can be generated by field-aligned currents. Thermal electrons can gain energy via betatron acceleration in a dipole magnetic field.
Parameter Estimation of Gaussian-Damped Sinusoids from a Geometric Perspective
Pelaia, Thomas
2016-01-01
The five parameter gaussian damped sinusoid equation is a reasonable model for betatron motion with chromatic decoherence of the proton bunch centroid signal in the ring at the Spallation Neutron Source. A geometric method for efficiently fitting this equation to the turn by turn signals to extract the betatron tune and damping constant will be presented. This method separates the parameters into global and local parameters and allows the use of vector arithmetic to eliminate the local parameters from the parameter search space. Furthermore, this method is easily generalized to reduce the parameter search space for a larger class of problems.
Yang, Xi [Brookhaven National Lab. (BNL), Upton, NY (United States); Huang, Xiaobiao [SLAC National Accelerator Lab., Menlo Park, CA (United States)
2016-08-01
We propose a method to simultaneously correct linear optics errors and linear coupling for storage rings using turn-by-turn (TbT) beam position monitor (BPM) data. The independent component analysis (ICA) method is used to isolate the betatron normal modes from the measured TbT BPM data. The betatron amplitudes and phase advances of the projections of the normal modes on the horizontal and vertical planes are then extracted, which, combined with dispersion measurement, are used to fit the lattice model. Furthermore, the fitting results are used for lattice correction. Our method has been successfully demonstrated on the NSLS-II storage ring.
Compensations of beam-beam resonances using crabbing schemes at large Piwinski crossing angles
We study combined effects of the crab crossing and of the crab waist lattice options on the luminosity performance of a collider where the crossing angle collisions are used. We have found that for collisions at large Piwinski angle a proper combination of the crab crossing and of the crab waist lattice insertions results in exact cancellation of all synchro-betatron as well as of all betatron coupling beam-beam resonances of odd orders. The beam-beam limitations on the luminosity for such a collider with the crossing angle collisions will be the same like that for a collider with head-on collisions of short bunches.
Global Decoupling on the RHIC Ramp
Luo, Yun; Della Penna, Al; Fischer, Wolfram; Laster, Jonathan S; Marusic, Al; Pilat, Fulvia Caterina; Roser, Thomas; Trbojevic, Dejan
2005-01-01
The global betatron decoupling on the ramp is an important issue for the operation of the Relativistic Heavy Ion Collider (RHIC). In the polarized proton run, the betatron tunes are required to keep almost constant on the ramp to avoid spin resonance line crossing and the beam polarization loss. Some possible correction schemes on the ramp, like three-ramp correction, the coupling amplitude modulation and the coupling phase modulaxtion, have been found. The principles of these schemes are shortly reviewed and compared. Operational results of their applications on the RHIC ramps are given.
Chicane and wiggler based bunch compressors for future linear colliders
In this paper, we discuss bunch compressors for future linear colliders. In the past, the bunch compression optics has been based upon achromatic cells using strong sextupoles to correct the dispersive and betatron chromaticity. To preserve the very small emittances required in most future collider designs, these schemes tend to have very tight alignment tolerances. Here, we describe bunch compressors based upon magnetic chicanes or wigglers which do need sextupoles to correct the chromatic emittance dilution. The dispersive chromaticity cancels naturally and the betatron chromaticity is not a significant source of emittance dilution. Thus, these schemes allow for substantially reduced alignment tolerances. Finally, we present a detailed design for the NLC linear collider
The chromatic correction in RHIC [Relativistic Heavy Ion Collider
The scheme for the correction of chromatic effects in the Relativistic Heavy Ion Collider at BNL is discussed. This scheme uses six families of sextupoles excited by four independent power supplies, and provides adequate control of linear and quadratic terms in the tune vs momentum dependence and reduces the variation of the betatron amplitude, vs momentum
Plasmas in particle accelerators: adiabatic theories for bunched beams
Three different formalisms for discussing Vlasov's equation for bunched beam problems with anharmonic space charge forces are outlined. These correspond to the use of a drift kinetic equation averaged over random betatron motions; a fluidkinetic adiabatic regime analogous to the theory of Chew, Goldberger, and Low; and an adiabatic hydrodynamic theory
A case of radiation necrosis seemingly appearing as brain tumor
A 56 years old female with late irradiation necrosis of the frontal cerebrum was presented. It appeared 3.5 years later of Betatron electron irradiation for the treatment of skin cancer along the forehead and simulated clinically to tumor of the frontal cerebrum. The patient underwent removal of that late irradiation necrosis and took satisfactory postoperative course. (auth.)
Simple model with damping of the mode-coupling instability
Pestrikov, D.V. [AN SSSR, Novosibirsk (Russian Federation). Inst. Yadernoj Fiziki
1996-08-01
In this paper we use a simple model to study the suppression of the transverse mode-coupling instability. Two possibilities are considered. One is due to the damping of particular synchrobetatron modes, and another - due to Landau damping, caused by the nonlinearity of betatron oscillations. (author)
The partial Siberian snake experiment at the Brookhaven AGS
We are building a 4.7 Tesla-meter room temperature solenoid to be installed in a 10-foot long AGS straight section. This experiment will test the idea of using a partial snake to correct all depolarizing imperfection resonances and also test the feasibility of betatron tune jump in correction intrinsic resonances in the presence of a partial snake
A simple method is described to determine the beam profile in an electron synchrotron; the measured results are compared with calculated values. Moreover, the influence of synchrotron- and betatron-oscillations on synchrotron radiation measurements is discussed, and a method is given to correct this. (orig.)
Czechoslovak congress of radiology with international participation
The booklet contains 125 abstracts of papers presented at the congress, dealing with diagnostic and therapeutic applications of X-rays, 60Co, 137Cs, betatron radiation, with scintigraphy, angiography, lymphography, with radiosensitizers, contrast media and with a host of activities performed and results achieved at radiological departments. (A.K.)
Induced radioactivity of steel components in industrial flaw inspection with electron accelerators
The results are presented of experimental investigations of the characteristics of gamma radiation of induced radioactivity of steel components and also of structural members of the accelerator/flaw detector. Semiempirical equations are proposed for determining the holding time of inspected components and the betatron which take into account the focusing distance, exposure time, and braking radiation intensity
In a study on the epidemiology of laryngeal and pharyngeal tumours, a coincidence was found between established alcohol abuse and tumours of the two organs. The results of surgery followed by gammatron radiotherapy (laryngeal tumours) or betatron therapy (pharyngeal tumours) are prescuted and discussed. (APR)
The production of photoneutrons and high-energy charged particles by betatrons and linear accelerators used in radiotherapy is measured. It is concluded there exists sufficient contamination in high-energy x-ray beams to be a consideration in certain radiotherapy situations
I point out that some of the findings reported in the commented paper are restatements of facts well known to workers in the field and some of the analysis of the orbital motion pays insufficient attention to the decomposition of the radial motion into betatron and dispersion terms. Some of the numerical studies of the spin precession time also contain discernible systematic errors
This retrospective study included 134 patients showing adenomas of the pituitary gland. It was found that radiotherapy carried out immediately after surgery was superior to radiation commencing only after tumour recidivation. Treatment was predominantly based an 'ultrahard' X-rays (betatron), to a lesser extent on cobalt-60 gamma rays. (MBC)
Kolski, Jeffrey S. [Los Alamos National Laboratory; Baily, Scott A. [Los Alamos National Laboratory; Bjorklund, Eric A. [Los Alamos National Laboratory; Bolme, Gerald O. [Los Alamos National Laboratory; Hall, Michael J. [Los Alamos National Laboratory; Kwon, Sung I. [Los Alamos National Laboratory; Martinez, Martin P. [Los Alamos National Laboratory; Prokop, Mark S. [Los Alamos National Laboratory; Shelley, Fred E. Jr. [Los Alamos National Laboratory; Torrez, Phillip A. [Los Alamos National Laboratory
2012-05-14
Beam position monitors (BPMs) are the primary diagnostic in the Los Alamos Proton Storage Ring (PSR). When injecting one turn, the transversemotion is approximated as a single particle with initial betatron position and angle {rvec x}{sub 0} and {rvec x}'{sub 0}. With single-turn injection, we fit the betatron tune, closed orbit (CO), and injection offset ({rvec x}{sub 0} and {rvec x}'{sub 0} at the injection point) to the turn-by-turn beam position. In production mode, we accumulate multiple turns, the transverse phase space fills after 5 injections (horizontal and vertical fractional betatron tunes {approx}0.2) resulting in no coherent betatron motion, and only the CO may be measured. The injection offset, which determines the accumulated beam size and is very sensitive to steering upstream of the ring, is not measurable in production mode. We describe our approach and ongoing efforts to measure the injection offset during production mode by injecting a 'diagnostic' pulse {approx}50 {micro}s after the accumulated beam is extracted. We also study the effects of increasing the linac RF gate length to accommodate the diagnostic pulse on the production beam position, transverse size, and loss.
Schottky noise analysis in linear accelerators
An application of Schottky noise analysis is theoretically presented for the diagnosis of intense beams in linacs. Induced currents by betatron/synchroton oscillations of particles as well as mismatched-envelope oscillations are calculated by applying different models. The induced currents are analytically Fourier-analyzed. Resulting power spectra show some stochastic peaks which reflect basic parameters of these oscillations. (orig.)
Thousand TeV in the center of mass: introduction to high-energy storage rings
The lecture discusses, in a pedagogic way, a hypothetical 500 TeV proton storage ring accelerator. It gives machine parameters, discusses linear optics and betatron motions, surveys questions of errors, tolerances and nonlinear resonances, and discusses some of the demands on the detection apparatus, especially the apparent inevitability of multiple interactions per bunch crossing
CESAR, 2 MeV electron storage ring; construction period; deflector.
Service Photo
1962-01-01
One of the 2 electrostatic deflectors (lying on its side) for monoturn injection of the beam from the van de Graaff. They bring the beam close and parallel to the closed orbit. 1/4 of a betatron wavelength downstream from the 2nd deflector, a pulsed inflector corrects the angle.
Synchrotron radiation based on laser-plasma interaction in the relativistic range
This work illustrates the experimental characterization of a new compact X-ray source: the Betatron X-ray source. It is the first time that collimated hard X-ray source is produced by laser. Through the focusing of an ultra-intense laser radiation (30 TW, 30 fs) on a helium plasma, the ponderomotive force linked to the light intensity gradient expels the plasma electrons forming an accelerating cavity in the wake of the laser plasma. Some electrons trapped in the back of this structure, are accelerated and oscillate to produce X-radiation. This document is composed of 8 chapters. The first one is a presentation of the topic. The second chapter gives an account of the physics behind the laser-plasma interaction in the relativistic range and for ultra-short pulses. The third chapter presents the theoretical characteristics of the Betatron X-ray source. This chapter begins with an analogy with current synchrotron radiation and the radiation emitted by an electron undergoing Betatron oscillations is described in terms of power, spectral intensity and photon flux. The fourth chapter is dedicated to the numerical simulation of the Betatron radiation. The trajectories of the electrons are computed from the equation of motion, taking into account longitudinal and transverse forces. The radiation emission term is then computed from the radiation equation detailed in the previous chapter. The fifth chapter presents the experimental setting to produce Betatron X-rays. The sixth chapter gives the experimental characterization of the source (size, divergence and spectrum) on one hand, and on the other hand studies how source flux and spectra vary when laser and plasma parameters change. The seventh chapter presents experimental methods used to characterize the electrons trajectories in the plasma wiggler. The last chapter draws some perspectives on this source in terms of improvement and uses. (A.C.)
The Dosimetric Parameters Investigation of the Pulsed X-ray and Gamma Radiation Sources
Stuchebrov, S. G.; Miloichikova, I. A.; Shilova, X. O.
2016-01-01
The most common type of radiation used for diagnostic purposes are X-rays. However, X-rays methods have limitations related to the radiation dose for the biological objects. It is known that the use of the pulsed emitting source synchronized with the detection equipment for internal density visualization of objects significant reduces the radiation dose to the object. In the article the analysis of the suitability of the different dosimetric equipment for the radiation dose estimation of the pulsed emitting sources is carried out. The approbation results on the pulsed X-ray generator RAP-160-5 of the dosimetry systems workability with the pulse radiation and its operation range are presented. The results of the dose field investigation of the portable betatron OB-4 are demonstrated. The depth dose distribution in the air, lead and water of the pulsed bremsstrahlung generated by betatron are shown.
A method is described for producing density modulations on an intense relativistic electron beam by the use of rf fields in a betatron configuration. In concept, a device embodying this method should be capable of producing short (1-10 ns) electron bunches from a long (10-100 ns) beam, and is expected to be relatively compact and to operate efficiently on low power and energy. The method requires that the azimuthal phase velocity of the rf wave equal the electron beam velocity. Depending on phase relative to the rf wave, electrons in the beam gain or lose energy and form bunches by the negative mass effect. The dynamics of the electrons in the combined rf wave and betatron field have been analyzed. An example of an rf electron beam buncher is given
Effect of the crab waist and of the micro-beta on the beam-beam instability
We calculate the luminosity and the strengths of the beam-beam resonances for colliders with large horizontal crossing angles. Achievable luminosities of such colliders can reach high values provided that the number of particles in colliding beams can be increased while the vertical β-function can be decreased till the mini-beta range. The crab waist option of the optics in the interaction region decreases (or, even vanishes) the strengths of two-dimensional betatron weak-strong beam-beam resonances and of their synchro-betatron satellites provided that β-functions at the interaction point can be decreased till the micro-beta range. This can help to increase the achievable value of the collider luminosity.
Single Particle Dynamics in a Quasi-Integrable Nonlinear Accelerator Lattice
Antipov, Sergey A; Valishev, Alexander
2016-01-01
Fermilab is constructing the Integrable Optics Test Accelerator (IOTA) as the centerpiece of the Accelerator R&D Program towards high-intensity circular machines. One of the factors limiting the beam intensity in present circular accelerators is collective instabilities, which can be suppressed by a spread of betatron frequencies (tunes) through the Landau damping mechanism or by an external damper, if the instability is slow enough. The spread is usually created by octupole magnets, which introduce the tune dependence on the amplitude and, in some cases, by a chromatic spread (tune dependence on particle's momentum). The introduction of octupoles usually lead to a resonant behavior and a reduction of the dynamic aperture. One of the goals of the IOTA research program is to achieve a high betatron tune spread, while retaining a large dynamic aperture using conventional octupole magnets in a special but realistic accelerator configuration. In this report, we present results of computer simulations of an el...
Wang, Huanyu; Huang, Can; Wang, Shui
2016-01-01
The interactions between magnetic islands are considered to play an important role in electron acceleration during magnetic reconnection. In this paper, two-dimensional (2-D) particle-in-cell (PIC) simulations are performed to study electron acceleration during multiple X line reconnection with a guide field. The electrons remain almost magnetized, and we can then analyze the contributions of the parallel electric field, Fermi and betatron mechanisms to electron acceleration during the evolution of magnetic reconnection by comparing with a guide-center theory. The results show that with the proceeding of magnetic reconnection, two magnetic islands are formed in the simulation domain. The electrons are accelerated by both the parallel electric field in the vicinity of the X lines and Fermi mechanism due to the contraction of the two magnetic islands. Then the two magnetic islands begin to merge into one, and in such a process electrons can be accelerated by the parallel electric field and betatron mechanisms. ...
Current pulse generator of an induction accelerator electromagnet
Thyristor generator forming in betatron electromagnet coil sinusoidal and quasisinusoidal current unipolar pulses, the field being deforced at the beginning of acceleration cycle, and with the pulse flat top in the cycle end, is described. The current amplitude is controlled by pulse-phase method. The current pulse time shift permitted to decrease the loss rate in the accumulating capacitor. The generator is used in systems with 1-10 ms pulse duration, electromagnet magnetic field maximal energy - 45-450 J, the voltage amplitude in the coil 960-1500 V and amplitude of the current passing the coil 100-500 A, the repetition frequency being 50-200 Hz. In particular, the generator is used to supply betatrons designed for defectoscopy in nonstationary conditions, the accelerated electron energy being 4, 6, 8 and 15 MeV
Beam diagnostic techniques, observations and comparison with theory
This paper presents the classes of the different methods of beam diagnostics available in modern storage rings. The first two use the near-field of the beam measured by the position monitors. The optical functions emdash betatron phase advances and beta functions emdash are obtained by exciting a betatron oscillation and measuring its phase and amplitude at the beam position monitors around the ring. Modern readout electronics, which memorize the readings taken in successive turns, are particularly well suited for this method. A second group of measurements is concerned with the properties of the beam itself. The frequency distribution of the particles can directly be deduced from the beam response to a harmonic excitation. Such measurements give also the beam stability and the impedance of the beam surroundings. The third class observes the far-field of the beam emitted as synchrotron radiation. Using this radiation for imaging or measuring its angular divergence gives the transverse beam dimensions
MEASUREMENTS AND MODELING OF EDDY CURRENT EFFECTS IN BNL'S AGS BOOSTER.
BROWN, K.A.; AHRENS, L.; GARDNER, C.; GLENN, J.W.; HARVEY, M.; MENG, W.; ZENO, K.
2006-06-23
Recent beam experiments at BNL's AGS Booster have enabled us to study in more detail the effects of eddy currents on the lattice structure and our control over the betatron tune. The Booster is capable of operating at ramp rates as high as 9 T/sec. At these ramp rates eddy currents in the vacuum chambers significantly alter the fields and gradients seen by the beam as it is accelerated. The Booster was designed with these effects in mind and to help control the field uniformity and linearity in the Booster Dipoles special vacuum chambers were designed with current windings to negate the affect of the induced eddy currents. In this report results from betatron tune measurements and eddy current simulations will be presented. We will then present results from modeling the accelerator using the results of the magnetic field simulations and compare these to the measurements.
Modeling Crabbing Dynamics in an Electron-Ion Collider
Castilla, Alejandro [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Old Dominion Univ., Norfolk, VA (United States); Univ. de Guanajuato (DCI-UG), Leon (Mexico); Morozov, Vasiliy S. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Satogata, Todd J. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Old Dominion Univ., Norfolk, VA (United States); Delayen, Jean R. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Old Dominion Univ., Norfolk, VA (United States)
2015-09-01
A local crabbing scheme requires π/2 (mod π) horizontal betatron phase advances from an interaction point (IP) to the crab cavities on each side of it. However, realistic phase advances generated by sets of quadrupoles, or Final Focusing Blocks (FFB), between the crab cavities located in the expanded beam regions and the IP differ slightly from π/2. To understand the effect of crabbing on the beam dynamics in this case, a simple model of the optics of the Medium Energy Electron-Ion Collider (MEIC) including local crabbing was developed using linear matrices and then studied numerically over multiple turns (1000 passes) of both electron and proton bunches. The same model was applied to both local and global crabbing schemes to determine the linear-order dynamical effects of the synchro-betatron coupling induced by crabbing.
A method to compensate the energy loss of a continuous stacked beam with a large momentum spread
A system of rectangular drift tube loaded cavities resonating in the TE 101 mode combined with a cyclic scaling guide field can be used to accelerate an unbunched beam of charged particles. The system is superior to phase displacement because the cavities are driven at a fixed frequency with certain phase differences between each other. The range of particle momenta is limited by rf-knock out. Rf-induced betatron oscillations and phase dependent momentum changes can be compensated by means of sixteen cavities on the circumference of the accelerator. The amplitude of the betatron oscillations and the energy gain were calculated numerically for storage devices consisting of a spiral-sector FFAG guide field and one or sixteen cavities, respectively, using measured rf-feld data. The systems seem to be practical only for electrons with an energy up to 100 MeV. The rf-system works within an energy width of several MeV. (Auth.)
The damper for the transverse instabilities of the SPS
Bossart, Rudolf; Gareyte, Jacques; de Raad, Bastiaan; Rossi, V
1979-01-01
For beam intensities above 10/sup 12/ protons per pulse in the SPS, collective transverse beam instabilities develop with frequencies between 15 kHz and 3 MHz because of the resistive wall effect of the vacuum chamber. An active feedback system with an electrostatic deflector has been installed in the SPS for damping the resistive wall instabilities in both the vertical and horizontal planes. Measurements have been made to determine the threshold and growth rate of these instabilities. As a novel application, the damper can be used also for the excitation of small coherent betatron oscillations. A phase-locked loop tracks the beam oscillations and provides a continuous display of the betatron wave-number Q during the cycle. (4 refs).
Algorithms for tracking of charged particles in circular accelerators
An important problem in accelerator design is the determination of the largest stable betatron amplitude. This stability limit is also known as the dynamic aperture. The equations describing the particle motion are non-linear, and the Linear Lattice Functions cannot be used to compute the stability limits. The stability limits are therefore usually searched for by particle tracking. One selects a set of particles with different betatron amplitudes and tracks them for many turns around the machine. The particles which survive a sufficient number of turns are termed stable. This paper concentrates on conservative systems. For this case the particle motion can be described by a Hamiltonian, i.e. tracking particles means application of canonical transformations. Canonical transformations are equivalent to symplectic mappings, which implies that there exist invariants. These invariants should not be destroyed in tracking
Chicane and wiggler based bunch compressors for future linear colliders
In this paper, the authors discuss bunch compressors for future linear colliders. In the past, the bunch compression optics has been based upon achromatic cells using strong sextupoles to correct the dispersive and betatron chromaticity. To preserve the very small emittances required in most future collider designs, these schemes tend to have very tight alignment tolerances. Here, the authors describe bunch compressors based upon magnetic chicanes or wigglers which do not need sextupoles to correct the chromatic emittance dilution. The dispersive chromaticity cancels naturally and the betatron chromaticity is not a significant source of emittance dilution. Thus, these schemes allow for substantially reduced alignment tolerances. Finally, they present a detailed design for the NLC linear collider
FEL gain taking into account diffraction and electron beam emittance; generalized Madey's theorem
We derive a formula for the free electron laser gain in the small-signal, low-grain regime which resembles closely the 1-D formula but taking into account the effect of wave diffraction and electron beam divergence and betatron motion. The formula is cast in a form which exhibits clearly the role of the transverse phase space distribution of photons and electrons. 8 refs
Asymmetric antiproton debuncher: No bad mixing, more good mixing
An asymmetric lattice for the Fermilab Antiproton Debuncher is designed. The lattice has zero mixing between the pickups and the kickers (bad mixing) while the mixing in the rest of the machine (good mixing) can be varied (even during the operation of the machine) in order to optimize the stochastic cooling. As an example, a lattice with zero bad mixing and twice the good mixing is presented. The betatron cooling rate in this lattice is twice its present value
Lattice design for head-on beam-beam compensation at RHIC
Montag, C.
2011-03-28
Electron lenses for head-on beam-beam compensation will be installed in IP 10 at RHIC. Compensation of the beam-beam effect experienced at IP 8 requires betatron phase advances of {Delta}{psi} = k {center_dot} {pi} between the proton-proton interaction point at IP 8, and the electron lens at IP 10. This paper describes the lattice solutions for both the BLUE and the YELLOW ring to achieve this goal.
Overview of accelerators in medicine
Accelerators used for medicine include synchrotrons, cyclotrons, betatrons, microtrons, and electron, proton, and light ion linacs. Some accelerators which were formerly found only at physics laboratories are now being considered for use in hospital-based treatment and diagnostic facilities. This paper presents typical operating parameters for medical accelerators and gives specific examples of clinical applications for each type of accelerator, with emphasis on recent developments in the field
A search for integrable four-dimensional nonlinear accelerator lattices
Nagaitsev, S.; Danilov, V.
2012-01-01
Integrable nonlinear motion in accelerators has the potential to introduce a large betatron tune spread to suppress instabilities and to mitigate the effects of space charge and magnetic field errors. To create such an accelerator lattice one has to find magnetic and/or electric field combinations leading to a stable integrable motion. This paper presents families of lattices with one invariant where bounded motion can be easily created in large volumes of the phase space. In addition, it pre...
Amplitude dependent orbital period in alternating gradient accelerators
S. Machida; Kelliher, D. J.; Edmonds, C. S.; Kirkman, I. W.; Berg, J. S.; Jones, J. K.; Muratori, B. D.; Garland, J. M.
2016-01-01
Orbital period in a ring accelerator and time of flight in a linear accelerator depend on the amplitude of betatron oscillations. The variation is negligible in ordinary particle accelerators with relatively small beam emittance. In an accelerator for large emittance beams like muons and unstable nuclei, however, this effect cannot be ignored. We measured orbital period in a linear non-scaling fixed field alternating gradient (FFAG) accelerator, which is a candidate for muon acceleration, and...
Design and Simulation of IOTA - a Novel Concept of Integrable Optics Test Accelerator
Nagaitsev, S.; Valishev, A.; Danilov, V. V.; Shatilov, D. N.
2013-01-01
The use of nonlinear lattices with large betatron tune spreads can increase instability and space charge thresholds due to improved Landau damping. Unfortunately, the majority of nonlinear accelerator lattices turn out to be nonintegrable, producing chaotic motion and a complex network of stable and unstable resonances. Recent advances in finding the integrable nonlinear accelerator lattices have led to a proposal to construct at Fermilab a test accelerator with strong nonlinear focusing whic...
Feedback implementation options and issues for B factory accelerators
The proposed B factory accelerator facilities will require active feedback systems to control multibunch instabilities. These feedback systems must operate in machines with thousands of circulating bunches and with short (2--4 ns) interbunch intervals. The functional requirements for transverse (betatron) and longitudinal (synchrotron) feedback systems are presented. Several possible implementation options are discussed and system requirements developed. Conceptual designs are presented for the PEP II transverse and longitudinal feedback systems
Ivanenko, I; Králik, S; Franko, J
2003-01-01
The present work is devoted to the development of software designed to analyze the results of measured isochronous cyclotrons magnetic fields. Software allows one to make calculations of basic magnetic field properties and compare up to six results of analyzed magnetic fields. Obtained results, such as average field, flutter, betatron frequency, harmonic's amplitude and phase, are presented graphically and can be saved as text files for further processing.
Balandin, V; Golubeva, N
2013-01-01
The problem of errors, arising due to finite BPM resolution, in the difference orbit parameters, which are found as a least squares fit to the BPM data, is one of the standard problems of the accelerator physics. In this article we present a "dynamical point of view" on this problem, which allows us to describe properties of the BPM measurement system in terms of the usual accelerator physics concepts of emittance and betatron functions.
A Schottky receiver for non-perturbative tune monitoring in the Tevatron
Transverse Schottky noise and coherent betatron modulation of the bunched beam revolution harmonics are continuously monitored by a sensitive receiver. The electronics relies upon low noise amplifiers, narrow-band filters, and spectrally pure oscillators to obtain a minimum detectable signal of -160 dBm. Dynamic range is 80 dB. Separate baseband proton and antiproton signals are continuously analyzed in the Main Control Room
Real-time modeling of transverse emittance growth due to ground motion
Ground motion noise at frequencies around 1 kHz causes growth of transverse emittance of the Superconducting Super Collider (SSC) collider beams. The effect was quantitatively investigated using real-time signals from seismometers installed at the tunnel depth and on the surface. The SSC beam was modeled as an ensemble of oscillators with a spread of betatron frequencies. The effect of transverse feedback on emittance growth was investigated
R.R. Wilson prize lecture: Adventures with accelerators
This paper is a very concise history of the authors experiences with particle accelerators, spanning his first experiences as a graduate student, through his professional career. His first experiences were visiting labs in Washington DC, and seeing equipment delivered to his school so large walls had to be moved for access. He saw larger machines in England, and was at GE when early betatrons were built, and when the first functional synchrotron was built
RHIC tracking studies with real magnets in real places
Results from RHIC tracking studies in which measured magnetic field errors are used in all arc magnets are reported. the dependence of betatron tunes on initial amplitudes, aspect ratio, and momentum are reported and are not significantly different from measured tune dependences when randomly generated magnetic field errors are used in all magnets. Survival plots at injection and storage are also consistent with previous determinations
Equation of spin motion in storage rings in a cylindrical coordinate system
Silenko, A. J.
2004-01-01
The exact equation of spin motion in a cylindrical coordinate system with allowance for electric dipole moments of particles has been derived. This equation is convenient for analytical calculations of spin dynamics in circular storage rings when the configuration of main fields is simple enough. The generalized formula for the influence of a vertical betatron oscillation on the angular velocity of spin rotation has been found. This formula agrees with the previously obtained result and conta...
SKODA Concern's present methods of non-destructive material testing
A survey is presented of methods used to detect various shapes, sizes and locations. Radioisotopes (192Ir, 60Co, 137Cs), X-ray apparatus and high energy radiation sources (betatron, the Neptun II linear accelerator) were used for radiographic testing. Ultrasound is used for testing basic materials, welds and overlays. Of surface methods the most frequently used are powder and capillary magnetic methods. Other methods used are acoustic emission and leak tests. (E.S.)
Synergistic Laser Wakefield/Direct Laser Acceleration in the Plasma Bubble Regime
Zhang, Xi; Khudik, Vladimir N.; Shvets, Gennady
2014-01-01
The concept of a hybrid laser wakefield/direct laser plasma accelerator is proposed. Relativistic electrons undergoing resonant betatron oscillations inside the plasma bubble created by a laser pulse are accelerated by gaining energy directly from the laser pulse and from its plasma wake. The resulting bifurcated phase space of self-injected plasma electrons contains a population that experiences wakefield acceleration beyond the standard one-dimensional limit because of the multi-dimensional...
Electron beam conditioning by Thomson scattering
Schroeder, C. B.; Esarey, E.; Leemans, W. P.
2003-01-01
A method is proposed for conditioning electron beams via Thomson scattering. The conditioning provides a quadratic correlation between the electron energy deviation and the betatron amplitude of the electrons, which results in enhanced gain in free-electron lasers. Quantum effects imply conditioning must occur at high laser fluence and moderate electron energy. Conditioning of x-ray free-electron lasers should be achievable with present laser technology, leading to significant size and c...
Beam Diagnosis and Lattice Modeling of the Fermilab Booster
Huang, Xiaobiao
2005-09-01
A realistic lattice model is a fundamental basis for the operation of a synchrotron. In this study various beam-based measurements, including orbit response matrix (ORM) and BPM turn-by-turn data are used to verify and calibrate the lattice model of the Fermilab Booster. In the ORM study, despite the strong correlation between the gradient parameters of adjacent magnets which prevents a full determination of the model parameters, an equivalent lattice model is obtained by imposing appropriate constraints. The fitted gradient errors of the focusing magnets are within the design tolerance and the results point to the orbit offsets in the sextupole field as the source of gradient errors. A new method, the independent component analysis (ICA) is introduced to analyze multiple BPM turn-by-turn data taken simultaneously around a synchrotron. This method makes use of the redundancy of the data and the time correlation of the source signals to isolate various components, such as betatron motion and synchrotron motion, from raw BPM data. By extracting clean coherent betatron motion from noisy data and separates out the betatron normal modes when there is linear coupling, the ICA method provides a convenient means to measure the beta functions and betatron phase advances. It also separates synchrotron motion from the BPM samples for dispersion function measurement. The ICA method has the capability to separate other perturbation signals and is robust over the contamination of bad BPMs. The application of the ICA method to the Booster has enabled the measurement of the linear lattice functions which are used to verify the existing lattice model. The transverse impedance and chromaticity are measured from turn-by-turn data using high precision tune measurements. Synchrotron motion is also observed in the BPM data. The emittance growth of the Booster is also studied by data taken with ion profile monitor (IPM). Sources of emittance growth are examined and an approach to cure
Impact on the magnetic compressor due to CSR
When an electron bunch is compressed in a chicane compressor, the CSR (coherent synchrotron radiation) will induce energy redistribution along the bunch. Such energy redistribution will affect the longitudinal emittance as a direct consequence. It will also excite betatron oscillation due to the chromatic transfer functions, and hence a transverse emittance change. So, it is indispensable for us to find a way to alleviate the CSR-caused emittance dilution and the bad result of chicane compressor in PKU-FEL. (authors)
Kim, H. J.; Sen, T.
2012-01-01
Beam collisions with a crossing angle at the interaction point have been applied in high intensity colliders to reduce the effects of parasitic collisions which induce emittance growth and beam lifetime deterioration. The crossing angle causes the geometrical reduction of the luminosity. Crab cavity can be one of the most promising ways to compensate the crossing angle and to realize effective head-on collisions. Moreover, the crab crossing mitigates the synchro-betatron resonances due to the...
An insertion to eliminate horizontal temperature of high energy electron beam
High energy electron cooling with a circulated electron bunch could significantly increase the luminosity of hadron colliders. One of the significant obstacles is high horizontal temperature of electron bunches, suppressing dramatically calculated cooling rates. Recently, a transformation of betatron coordinates and angles for elimination of the radial temperature was found. In our paper, we present a simple scheme to make up this transformation by thin quadruples, drifts and a solenoid
Resonance Method of Electric-Dipole-Moment Measurements in Storage Rings
A 'resonance method' of measuring the electric dipole moment (EDM) of nuclei in storage rings is described, based on two new ideas: (1) Oscillating particles' velocities in resonance with spin precession, and (2) alternately producing two sub-beams with different betatron tunes--one sub-beam to amplify and thus make it easier to correct ring imperfections that produce false signals imitating EDM signals, and the other to make the EDM measurement
RESONANCE METHOD OF ELECTRIC-DIPOLE-MOMENT MEASUREMENTS IN STORAGE RINGS.
ORLOV, Y.F.; MORSE, W.M.; SEMERTZIDIS, Y.K.
2006-05-10
A ''resonance method'' of measuring the electric dipole moment (EDM) of nuclei in storage rings is described, based on two new ideas: (1) Oscillating particles velocities in resonance with spin precession, and (2) alternately producing two sub-beams with different betatron tunes--one sub-beam to amplify and thus make it easier to correct ring imperfections that produce false signals imitating EDM signals, and the other to make the EDM measurement.
Septum magnet for electron extraction system at the synchrotron EPI
Extraction from the Yerevan synchrotron is carried out by the build-up resonance of the betatron oscillation amplitudes, and kicking electrons at the bending magnets with the current sheet. There are two septum magnets in the accelerator, the first one with thin current sheet for bending of the part of the electrons to the required distance necessary for passing through the vacuum chamber and reaching the working region of the second septum magnet. (R.P.) 3 refs.; 4 figs.; 1 tab
Simulations and Measurements of Stopbands in the Fermilab Recycler
Ainsworth, Robert [Fermilab; Adamson, Philip [Fermilab; Hazelwood, Kyle [Fermilab; Kourbanis, Ioanis [Fermilab; Stern, Eric [Fermilab
2016-06-01
Fermilab has recently completed an upgrade to the complex with the goal of delivering 700 kW of beam power as 120 GeV protons to the NuMI target. A major part of boosting beam power is to use the Fermilab Recycler to stack protons. Simulations focusing on the betatron resonance stopbands are presented taking into account different effects such as intensity and chromaticity. Simulations are compared with measurements.
Progress in studies of Electron-Cloud-Induced Optics Distortions at CESRTA
Crittenden, J. A.
2010-01-01
The Cornell Electron Storage Ring Test Accelerator (CesrTA) program has included extensive measurements of coherent betatron tune shifts for a variety of electron and positron beam energies, bunch population levels, and bunch train configurations. The tune shifts have been shown to result primarily from the interaction of the beam with the space-charge field of the beam-induced lowenergy electron cloud in the vacuum chamber. Comparison to several advanced electron cloud simulation program pac...
Tolerances for the vertical emittance in damping rings
Future damping rings for linear colliders will need to have very small vertical emittances. In the limit of low beam current, the vertical emittance is primarily determined by the vertical dispersion and the betatron coupling. In this paper, the contributions to these effects from random misalignments are calculated and tolerances are derived to limit the vertical emittance with a 95% confidence level. 10 refs., 5 figs
Electron beams: Physical and clinical aspects
Megavoltage electron beams represent an important treatment modality in modern radiotherapy, often providing a unique option in the treatment of superficial tumours (less than 5 cm deep). Electrons have been used in radiotherapy since the early 1950s, first produced by betatrons and then by microtrons and linacs. Modern high energy linacs typically provide, in addition to two megavoltage photon energies, several electron beam energies in the range from 4 to 22 MeV
Leemann, B.; Peggs, S.; Peterson, J.
1985-10-01
Utility straight sections are insertions in the SSC lattice to provide relatively free space to facilitate various beam manipulations. These uses include beam-abort, injection (and conceivably ejection), space for the rf system, and collimation. A typical utility straight section is 1500 meters in overall length (ranging from 500 to 1200 meters). It has zero dispersion and high values of the beta functions. The betatron phase shift across the insertion is about 90{degrees} in each plane.
Magnetic field quality requirements for PEP
The field quality of the cell quadrupole magnets of PEP was previously studied. With an improved formula, which takes into account the synchrotron oscillations, the field quality of the bending magnets and of the insertion quadrupole magnets is studied. An attempt is made to give a quality parameter. The instability prediction given by the betatron frequency shifts is compared with the instability prediction given by a particle tracing program
Electric Field Effects and the Experimental Value of the Muon g-2 Anomaly
Widom, A.; Srivastava, Y. N.
2001-01-01
The electric field corrections to the recently measured muon magnetic moment g-2 anomaly are considered from both the classical (BMT) and the quantum mechanical (Dirac) viewpoints. In both views, we prove that the electric field inducing the horizontal betatron tune does not renormalize the anomaly frequency. With this result kept in mind, the experimental muon magnetic moment anomaly is in closer agreement with standard model predictions than has been previously reported.
Schottky signal analysis: tune and chromaticity computation
Chanon, Ondine
2016-01-01
Schottky monitors are used to determine important beam parameters in a non-destructive way. The Schottky signal is due to the internal statistical fluctuations of the particles inside the beam. In this report, after explaining the different components of a Schottky signal, an algorithm to compute the betatron tune is presented, followed by some ideas to compute machine chromaticity. The tests have been performed with offline and/or online LHC data.
Birth of colliding beams in Europe, two photon studies at Adone
Bonolis, Luisa
2015-01-01
This article recalls the birth of the first electron-positron storage ring AdA, and the construction of the higher energy collider ADONE, where early photon-photon collisions were observed. The events which led the Austrian physicist Bruno Touschek to propose and construct AdA will be recalled, starting with early work on the Wideroe's betatron during World War II, up to the construction of ADONE, and the theoretical contribution to radiative corrections to electron-positron collisions.
Feedback implementation options and issues for B factory accelerators
The proposed B factory accelerator facilities will require active feedback systems to control multibunch instabilities. These feedback systems must operate in machines with thousands of circulating bunches and with short (2-4 ns) interbunch intervals. The functional requirements for transverse (betatron) and longitudinal (synchrotron) feedback systems are presented. Several possible implementation options are discussed and system requirements developed. Conceptual designs are presented for the PEP II transverse and longitudinal feedback systems
Low emittance lattice optimization using a multi-objective evolutionary algorithm
A low emittance lattice design and optimization procedure are systematically studied with a non-dominated sorting-based multi-objective evolutionary algorithm which not only globally searches the low emittance lattice, but also optimizes some beam quantities such as betatron tunes, momentum compaction factor and dispersion function simultaneously. In this paper the detailed algorithm and lattice design procedure are presented. The Hefei light source upgrade project storage ring lattice, with fixed magnet layout, is designed to illustrate this optimization procedure. (authors)
Effect of undulators on the stored electron beam of Indus-2
Abdurrahim; A.D.Ghodke
2015-01-01
Indus-2 is an Indian synchrotron light source,operating at 2.5 GeV and generating synchrotron radiation from its bending magnets.In order to provide more intense synchrotron radiation to the synchrotron users,there is a plan to install five insertion devices in the Indus-2 storage ring.In the first phase of installation of insertion devices,there is a proposal to install two out-vacuum pure permanent magnet linearly polarized undulators in long straight sections of the Indus-2 storage ring.The presence of the insertion devices in the ring has inevitable effects on beam parameters like betatron tune,betatron amplitude function,closed orbit,emittance,energy spread and dynamic aperture etc.In this paper,the effect of two undulators on the above mentioned parameters of the Indus-2 stored electron beam at 2.5 GeV is presented.Moreover a correction scheme for the restoration of the betatron tune and amplitude function is also presented.
Integrable Accelerator Lattices With Periodic And Exponential Invariants
This paper presents a new variety of one-dimensional nonlinear integrable accelerator lattices with periodic and exponential invariants in coordinates and momenta. Extension to two-dimensional transverse motion, based on a recently published approach, is discussed. The integrable accelerator lattices represent a continuation of linear systems with Courant-Snyder invariants to the nonlinear domain, where the frequencies of betatron motion 'strongly' depend on betatron amplitudes (the word 'strongly' means that the spread of betatron tunes is comparable to the tune itself). This spread can help to advance beam intensities by introducing a very large Landau damping. Recently, a possible method to realize stable integrable motion in accelerators with 2D transverse magnetic field was suggested (1). In principle, all 1D integrable lattices with short nonlinear lenses can be converted to 2D integrable lattices (we'll show examples of this conversion later in this paper). Reference (2) presented a method to find a vast variety of 1D and 2D integrable systems with invariants, polynomial in coordinates and momenta. The same method was used to find invariants that are harmonic or exponential functions of coordinates and momenta. Here we briefly present the theory and the method, along with solutions for lattices having nonlinear kicks with the aforementioned invariants, and show the behaviour of these integrable lattices in the 2D case with transverse magnetic fields.
Quasiperiodic spin-orbit motion and spin tunes in storage rings
Barber, D.P.; Heinemann, K.; Ellison, J.A. [New Mexico Univ., Albuquerque, NM (United States). Dept. of Mathematics and Statistics
2004-12-01
We present an in-depth analysis of the concept of spin precession frequency for integrable orbital motion in storage rings. Spin motion on the periodic closed orbit of a storage ring can be analyzed in terms of the Floquet theorem for equations of motion with periodic parameters and a spin precession frequency emerges in a Floquet exponent as an additional frequency of the system. To define a spin precession frequency on nonperiodic synchro-betatron orbits we exploit the important concept of quasiperiodicity. This allows a generalization of the Floquet theorem so that a spin precession frequency can be defined in this case too. This frequency appears in a Floquet-like exponent as an additional frequency in the system in analogy with the case of motion on the closed orbit. These circumstances lead naturally to the definition of the uniform precession rate and a definition of spin tune. A spin tune is a uniform precession rate obtained when certain conditions are fulfilled. Having defined spin tune we define spin-orbit resonance on synchro-betatron orbits and examine its consequences. We give conditions for the existence of uniform precession rates and spin tunes (e.g. where small divisors are controlled by applying a Diophantine condition) and illustrate the various aspects of our description with several examples. The formalism also suggests the use of spectral analysis to ''measure'' spin tune during computer simulations of spin motion on synchro-betatron orbits. (orig.)
Recent work has shown that encounters of particles with separatrices in adiabatically varying Hamiltonian systems leads to spreading of the adiabatic invariant. This process can lead to transport of particles through phase space. Indeed, it can lead to loss of particles in accelerators by the transport of particles from integrable (confined) regions to nonintegrable regions. This research is applicable to a number of accelerator systems. For example, synchrotron oscillations cause tunes, resonance locations, and resonance sizes to change slowly in the betatron degrees of freedom. Particles can, therefore, be trapped in betatron resonances and transported to regions of larger betatron oscillation amplitude, where confining KAM curves may not exist. In the radiofrequency quadrupole, particles trap in buckets at the injection end and detrap at the high-energy end. In both processes the separatrix is crossed. The goal of this research is to understand the rate of phase-space spreading due to separatrix crossing. So far we have accomplished the following: (1) we have shown that correlations between separatrix crossings are significant. (2) By numerical integration we have shown that ''separatrix crossed phase space'' is nevertheless ergodic. (3) Numerical integrations also show that the diffusion rate scales as the third power of the adiabaticity parameter ε
X-ray Synchrotron Radiation in a Plasma Wiggler
Wang, Shuoquin; /UCLA /SLAC, SSRL
2005-09-27
A relativistic electron beam can radiate due to its betatron motion inside an ion channel. The ion channel is induced by the electron bunch as it propagates through an underdense plasma. In the theory section of this thesis the formation of the ion channel, the trajectories of beam electrons inside the ion channel, the radiation power and the radiation spectrum of the spontaneous emission are studied. The comparison between different plasma wiggler schemes is made. The difficulties in realizing stimulated emission as the beam traverses the ion channel are investigated, with particular emphasis on the bunching mechanism, which is important for the ion channel free electron laser. This thesis reports an experiment conducted at the Stanford Linear Accelerator Center (SLAC) to measure the betatron X-ray radiations for the first time. They first describe the construction and characterization of the lithium plasma source. In the experiment, the transverse oscillations of the SLAC 28.5 GeV electron beam traversing through a 1.4 meter long lithium plasma source are clearly seen. These oscillations lead to a quadratic density dependence of the spontaneously emitted betatron X-ray radiation. The divergence angle of the X-ray radiation is measured. The absolute photon yield and the spectral brightness at 14.2 KeV photon energy are estimated and seen to be in reasonable agreement with theory.
Resonance and coupling effects in circular accelerators
This thesis deals with a general theory for the description of resonance and coupling effects in circular particle accelerators. The theory is mainly applied to the proposed proton accumulator ring IKOR in West Germany and to an electron storage ring which is characteristic of existing synchrotron radiation facilities (PAMPUS; this project has since been dismissed by the Dutch government). In chapter 1 the author expands the general Hamilton function for the description of the relativistic particle motion in a time-dependent magnetic field and a HF accelerating electric field (in order to study transverse-longitudinal coupling effects) as well as for the motion in a time-independent magnetic field without acceleration (to study transverse coupling effects). The linear transverse motion is discussed in chapter 2. Analytical formulae for the so-called Twiss parameters are derived from the linear Hamilton theory. The simultaneous treatment of the betatron and synchrotron motion is developed in chapter 3 and a theory for the description of the one-dimensional non-linear betatron motion is elaborated in chapter 4. The two-dimensional non-linear betatron resonances are treated in chapter 5. The description of these resonances can be reduced rather simply to a one-dimensional problem and are treated by examination of trajectories in a phase plane. (Auth.)
Generation of femtosecond γ-ray bursts stimulated by laser-driven hosing evolution.
Ma, Yong; Chen, Liming; Li, Dazhang; Yan, Wenchao; Huang, Kai; Chen, Min; Sheng, Zhengming; Nakajima, Kazuhisa; Tajima, Toshiki; Zhang, Jie
2016-01-01
The promising ability of a plasma wiggler based on laser wakefield acceleration to produce betatron X-rays with photon energies of a few keV to hundreds of keV and a peak brilliance of 10(22)-10(23) photons/s/mm(2)/mrad(2)/0.1%BW has been demonstrated, providing an alternative to large-scale synchrotron light sources. Most methods for generating betatron radiation are based on two typical approaches, one relying on an inherent transverse focusing electrostatic field, which induces transverse oscillation, and the other relying on the electron beam catching up with the rear part of the laser pulse, which results in strong electron resonance. Here, we present a new regime of betatron γ-ray radiation generated by stimulating a large-amplitude transverse oscillation of a continuously injected electron bunch through the hosing of the bubble induced by the carrier envelope phase (CEP) effect of the self-steepened laser pulse. Our method increases the critical photon energy to the MeV level, according to the results of particle-in-cell (PIC) simulations. The highly collimated, energetic and femtosecond γ-ray bursts that are produced in this way may provide an interesting potential means of exploring nuclear physics in table top photo nuclear reactions. PMID:27457890
Stuchebrov, S. G.; Miloichikova, I. A.; Danilova, I. B.
2016-01-01
The article describes a new technique for the average values of radiation dose measurement for the unstable gamma-ray sources which are used in non-destructive testing. The method is based on usage of different types of compact accumulative dosimeters. Spatially distributed position sensitive dosimetry system based on compact sensitive elements was created. Size and spatial resolution of the system of the dosimetry system are chosen taking into account sources characteristics. The proposed method has been tested on the measurement of dose distribution of several sources of X-ray and gamma-radiation based on X-ray tubes, electronic accelerator betatrons and linear electron accelerators.
Visualization of the nonlinear laser-plasma expansion
Láska, Leoš; Krouský, Eduard; Jungwirth, Karel; Krása, Josef; Pfeifer, Miroslav; Rohlena, Karel; Skála, Jiří; Ullschmied, Jiří; Velyhan, Andriy
2011-01-01
Roč. 39, č. 11 (2011), s. 2786-2787. ISSN 0093-3813 R&D Projects: GA MŠk(CZ) LC528; GA AV ČR IAA100100715; GA MŠk(CZ) 7E08094 Grant ostatní: FP 7 Extreme light infrastructure preparatory phase (ELI-PP)(XE) INFRA-2007-2.2-01 212105 Institutional research plan: CEZ:AV0Z10100523; CEZ:AV0Z20430508 Keywords : laser-produced plasma * self-focusation * betatron oscillations Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.174, year: 2011
Decoupling correction system in RHIC
A global linear decoupling in the Relativistic Heavy Ion Collider (RHIC) is going to be performed with the three families of skew quadrupoles. The operating horizontal and vertical betatron tunes in the RHIC will be separated by one unit vx=28.19 and vy=29.18. The linear coupling is corrected by minimizing the tune splitting Dn-the off diagonal matrix m. The skew quadrupole correction system is located close to the each of the six interaction regions. A detail study of the system is presented by the use of the TEAPOT accelerator physics code
Behaviour of space-charge dominated ion beams in storage rings
The interparticle repulsion, or space charge, limits the density of charged particle beams that can be obtained in storage rings. In this report we study the effect of increasing the space charge, with an exact computation of the lattice parameters using SYNCH. Systematically increasing the ion density by decreasing the emittance with cooling techniques lowers the betatron tune, until the lower half-integral stopband resonance -- also induced by the beam is reached. In the simple model described in the report, the amount of ''cooling'' is limited by the encountered stopband of the lattice. Therefore, machines with a higher tune and larger periodicity are better suited to store beams with high space charge
COMMISSIONING OF RHIC AT 100 GEV / NUCLEON.
TRBOJEVIC,D.; AHRENS,L.; BLASKIEWICZ,M.; BRENNAN,J.M.; BAI,M.; CAMERON,P.; CARDONA,J.; CONNOLLY,R.; DREES,A.; FLILLER,R.P.; ET AL
2002-06-02
This report describes commissioning of the Relativistic Heavy Ion Collider (RHIC) for 100 GeV/nucleon collisions at designed luminosity. To achieve these goals new systems had to be commissioned: Gamma-t transition crossing jump quadrupoles, rebucketing with the new RF storage cavities, phase lock loop feedback, betatron and crystal collimation, beta squeeze along the ramp, Siberian snake magnets for the proton polarization run, AC dipole system chromaticity measurements along the acceleration ramp, orbit correction, new ramp management system, upgraded sequencer, new data instrumentation and logger acquisition system etc.
Emittance growth from transient coherent synchrotron radiation
If the energies of individual particles in a bunch change as the bunch traverses a bending system, even if it is achromatic, betatron oscillations can be excited. Consequently, the transverse emittance of the bunch will grow as it moves downstream. Short bunches may be particularly susceptible to emission of coherent synchrotron radiation which can act back on the particles to change their energies and trajectories. Because a bend spans a well-defined length and angle, the bunch-excited wakefield and its effect back on the bunch are inherently transient. We outline a recently developed theory of this effect and apply it to example bending systems
Piecewise-homogeneous model for electron side injection into linear plasma waves
Golovanov, A. A.; Kostyukov, I. Yu.
2016-09-01
An analytical piecewise-homogeneous model for electron side injection into linear plasma waves is developed. The dynamics of transverse betatron oscillations are studied. Based on the characteristics of the transversal motion the longitudinal motion of electrons is described. The electron parameters for which the electron trapping and subsequent acceleration are possible are estimated. The analytical results are verified by numerical simulations in the scope of the piecewise-homogeneous model. The results predicted by this model are also compared to the results given by a more realistic inhomogeneous model.
Stochastic cooling equipment at the ISR
1983-01-01
The photo shows (centre) an experimental set-up for stochastic cooling of vertical betatron oscillations, used at the ISR in the years before the ICE ring was built. Cooling times of about 30 min were obtained in the low intensity range (~0.3 A). To be noted the four 50 Ohm brass input/output connections with cooling fins, and the baking-out sheet around the cylinder. On the left one sees a clearing electrode box allowing the electrode current to be measured, and the pressure seen by the beam to be evaluated.
Amplitude-dependent orbital period in alternating gradient accelerators
Machida, S.; Kelliher, D. J.; Edmonds, C. S.; Kirkman, I. W.; Berg, J. S.; Jones, J. K.; Muratori, B. D.; Garland, J. M.
2016-03-01
Orbital period in a ring accelerator and time of flight in a linear accelerator depend on the amplitude of betatron oscillations. The variation is negligible in ordinary particle accelerators with relatively small beam emittance. In an accelerator for large emittance beams like muons and unstable nuclei, however, this effect cannot be ignored. We measured orbital period in a linear non-scaling fixed-field alternating-gradient accelerator, which is a candidate for muon acceleration, and compared it with the theoretical prediction. The good agreement between them gives important ground for the design of particle accelerators for a new generation of particle and nuclear physics experiments.
BAI,M.; ROSER, T.
2007-06-25
This paper proposes a new design of spin flipper for RHIC to obtain full spin flip with the spin tune staying at half integer. The traditional technique of using an rf dipole or solenoid as spin flipper to achieve full spin flip in the presence of full Siberian snake requires one to change the snake configuration to move the spin tune away from half integer. This is not practical for an operational high energy polarized proton collider like RHIC where beam lifetime is sensitive to small betatron tune change. The design of the new spin flipper as well as numerical simulations are presented.
Observation of a hybrid spin resonance
Bai; Allgower; Ahrens; Alessi; Brown; Bunce; Cameron; Chu; Courant; Glenn; Huang; Jeon; Kponou; Krueger; Luccio; Makdisi; Lee; Ratner; Reece; Roser; Spinka; Syphers; Tsoupas; Underwood; van Asselt W; Williams
2000-02-01
A new type of spin depolarization resonance has been observed at the Brookhaven Alternating Gradient Synchrotron (AGS). This spin resonance is identified as a strong closed-orbit sideband around the dominant intrinsic spin resonance. The strength of the resonance was proportional to the 9th harmonic component of the horizontal closed orbit and proportional to the vertical betatron oscillation amplitude. This "hybrid" spin resonance cannot be overcome by the partial snake at the AGS, but it can be corrected by the harmonic orbit correctors. PMID:11017474
Magnetic transport channel for high-energy linacs
High-energy linacs, as proposed for future linear colliders, are a severe challenge to the magnetic transport system. The large number of magnets and the low beam emittance require tolerances on the displacement jitter in the submicron region. By choosing a low phase advance per cell, mounting the magnets two by two on rigid girders, and fixing all girders within one betatron wavelength on one beam, the tolerances are considerably relieved. The tolerances on one beam are now a few microns, and between beams they are some tens of microns
Ferrario, M; Palumbo, L
2014-01-01
The space charge forces are those generated directly by the charge distribution, with the inclusion of the image charges and currents due to the interaction of the beam with a perfectly conducting smooth pipe. Space charge forces are responsible for several unwanted phenomena related to beam dynamics, such as energy loss, shift of the synchronous phase and frequency , shift of the betatron frequencies, and instabilities. We will discuss in this lecture the main feature of space charge effects in high-energy storage rings as well as in low-energy linacs and transport lines.
On use of intraoperative radiotherapy during plastic surgery for lung cancer
The experience of applying the intraoperative radiotherapy (IORT) by the lung cancer bronchoplastic surgery in 28 patients is described. The irradiation was conducted with application of a small-size pulse betatron (SPB-6e), which makes it possible to obtain the fast electrons beam of 6 MeV. The single irradiation dose constituted 10-15 Gy. It is shown, that the IORT may be applied by bronchoplastic operations of the lung cancer, as the stage of combined treatment without deteriorating the structure and quantity of the postoperational complications
Current-pulse generator for electromagnet of induction accelerator
A thyristor generator is described that produces in the winding of the electromagnet of a betatron unipolar current pulses of sinusoidal and quasisinusoidal shape with deforcing of the field at the beginning of an acceleration cycle and with a plateau on the pulse top at the end of a cycle. The current amplitude is controlled by a pulse-phase method. The generator is used in apparatus with a pulse duration of 1-10 msec, a maximum electromagnet field energy 45-450 J, a winding voltage of 960-1500 V, and a winding current of 100-500 A for a repetition frequency of 50-200 Hz
Laser wakefield accelerator based light sources: potential applications and requirements
Albert, F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). NIF and Photon Sciences; Thomas, A. G. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Nuclear Engineering and Radiological Sciences; Mangles, S. P.D. [Imperial College, London (United Kingdom). Blackett Lab.; Banerjee, S. [Univ. of Nebraska, Lincoln, NE (United States); Corde, S. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Flacco, A. [ENSTA, CNRS, Ecole Polytechnique, Palaiseau (France); Litos, M. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Neely, D. [Science and Technology Facilities Council (STFC), Oxford (United Kingdom). Rutherford Appleton Lab. (RAL). Central Laser Facility; Viera, J. [Univ. of Lisbon (Portugal). GoLP-Inst. de Plasmas e Fusao Nuclear-Lab. Associado; Najmudin, Z. [Imperial College, London (United Kingdom). Blackett Lab.; Bingham, R. [Science and Technology Facilities Council (STFC), Oxford (United Kingdom). Rutherford Appleton Lab. (RAL). Central Laser Facility; Joshi, C. [Univ. of California, Los Angeles, CA (United States). Dept. of Electrical Engineering; Katsouleas, T. [Duke Univ., Durham, NC (United States). Platt School of Engineering
2015-01-15
In this article we review the prospects of laser wakefield accelerators as next generation light sources for applications. This work arose as a result of discussions held at the 2013 Laser Plasma Accelerators Workshop. X-ray phase contrast imaging, X-ray absorption spectroscopy, and nuclear resonance fluorescence are highlighted as potential applications for laser-plasma based light sources. We discuss ongoing and future efforts to improve the properties of radiation from plasma betatron emission and Compton scattering using laser wakefield accelerators for these specific applications.
Achromatic Cooling Channel with Li Lenses
Balbekov, V. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
2002-04-29
A linear cooling channel with Li lenses, solenoids, and 201 MHz RF cavities is considered. A special lattice design is used to minimize chromatic aberrations by suppression of several betatron resonances. Transverse emittance of muon beam decreases from 2 mm to 0.5 mm at the channel of about 110 m length. Longitudinal heating is modest, therefore transmission of the channel is rather high: 96% without decay and 90% with decay. Minimal beam emittance achievable by similar channel estimated as about 0.25 mm at surface field of Li lenses 10 T.
Compensation of the space charge force in a synchrotron by means of a RF quadrupole
Fang, S.
1982-04-01
Quantitative analysis of the space charge force compensation by means of RF quadrupoles in a synchrotron is given. For a bunched beam, if the RF quadrupoles operating at the fundamental RF frequency (or at most the fundamental and second harmonic frequency) are applied, the linear betatron tune shift ..delta nu.., excited by the linear part of space charge force, would be diminished effectively for most particles in either a parabolic or Gaussian distribution in the longitudinal direction. Then the space charge limit of a synchrotron, mainly decided by the nonlinear tune shift, would be raised to about twice that given by the Laslett formula.
The 42Ca photoneutron cross section
The measurement of the 42Ca(γ,nsub(t)) is reported here over the energy range 10.5 - 28 MeV. Bremsstrahlung radiation from the 35 MeV Betatron at this University was used to measure a yield curve of photoneutrons, from which the (γ,nsub(t)) cross section was derived. Since proton and neutron emission are the major decay modes of the giant dipole resonance, summing these cross sections approximates the photo-absorption cross section. With this information the theoretical predictions can be checked
Electron therapy of vulva cancer patients
Some peculiarities of combined treatment of patients with vulva carcinoma are considered in the case of applying the electron beam of the Soviet medical betatron B5M-25 with the energies of 10-25 MeV. The technique and results of treating 21 patients with vulva carcinoma are presented. 19 patients live 3 and more years after the finishing of electron therapy without relapses and metastases of vulva carcinoma. The analysis of literature and the results obtained permit to consider the clinical application of the method prospective
Luminosity dilution due to random offset beam-beam interaction
We consider beam-beam interaction in a collider in the case when the beams randomly displace around the equilibrium orbit at the interaction point. Due to the random part of the interaction, particles diffuse over the betatron amplitude causing an emittance growth of the beam. A Fokker-Planck equation is derived in which a diffusion coefficient is related with the spectral density of the noise. Estimations for the Superconducting Super Collider parameters give a tolerable level of the high-frequency beam offset at the interaction point. 2 refs
Emittance Growth at LHC Injection from SPS and LHC Kicker Ripple
Kotzian, G; Ducimetière, L; Goddard, B; Höfle, Wolfgang
2008-01-01
Fast pulsed kicker magnets are used to extract beams from the SPS and inject them into the LHC. The kickers exhibit time-varying structure in the pulse shape which translates into small offsets with respect to the closed orbit at LHC injection. The LHC damper systems will be used to damp out the resulting betatron oscillations, to keep the growth in the transverse emittance within specification. This paper describes the results of the measurements of the kicker ripple for the two systems, both in the laboratory and with beam, and presents the simulated performance of the transverse damper in terms of beam emittance growth. The implications for LHC operation are discussed.
A search for integrable four-dimensional nonlinear accelerator lattices
Nagaitsev, S
2012-01-01
Integrable nonlinear motion in accelerators has the potential to introduce a large betatron tune spread to suppress instabilities and to mitigate the effects of space charge and magnetic field errors. To create such an accelerator lattice one has to find magnetic and/or electric field combinations leading to a stable integrable motion. This paper presents families of lattices with one invariant where bounded motion can be easily created in large volumes of the phase space. In addition, it presents two examples of integrable nonlinear accelerator lattices, realizable with longitudinal-coordinate-dependent magnetic or electric fields with the stable nonlinear motion, which can be solved in terms of separable variables.
Ring for test of nonlinear integrable optics
Valishev, A; Kashikhin, V; Danilov, V
2011-01-01
Nonlinear optics is a promising idea potentially opening the path towards achieving super high beam intensities in circular accelerators. Creation of a tune spread reaching 50% of the betatron tune would provide strong Landau damping and make the beam immune to instabilities. Recent theoretical work has identified a possible way to implement stable nonlinear optics by incorporating nonlinear focusing elements into a specially designed machine lattice. In this report we propose the design of a test accelerator for a proof-of-principle experiment. We discuss possible studies at the machine, requirements on the optics stability and sensitivity to imperfections.
Nonlinear Theory of Nonparaxial Laser Pulse Propagation in Plasma Channels
Nonparaxial propagation of ultrashort, high-power laser pulses in plasma channels is examined. In the adiabatic limit, pulse energy conservation, nonlinear group velocity, damped betatron oscillations, self-steepening, self-phase modulation, and shock formation are analyzed. In the nonadiabatic limit, the coupling of forward Raman scattering (FRS) and the self-modulation instability (SMI) is analyzed and growth rates are derived, including regimes of reduced growth. The SMI is found to dominate FRS in most regimes of interest. (c) 2000 The American Physical Society
X-Y coupling generation with AC/pulsed skew quadrupole and its application
The new method of x-y coupling generation with AC or pulsed skew quadrupole is proposed. With this method, no difference resonance is requested; therefore the horizontal and vertical tunes should not be the same value. The AC skew quadrupole is driven by the difference frequency of horizontal and vertical betatron frequency to convert the horizontal position frequency to the vertical kick frequency and vice versa, therefore the coupling with this method is on resonance and can be driven to full coupling strength. In this report, the principle, simulation result, and possible applications are descried. (author)
Demonstration of coupling correction below the per-mil limit in the LHC
Maclean, Ewen Hamish; Fartoukh, Stephane; Persson, Tobias Hakan Bjorn; Skowronski, Piotr Krzysztof; Tomas Garcia, Rogelio; Wierichs, David Alexander; CERN. Geneva. ATS Department
2016-01-01
Linear coupling between betatron motion in the transverse planes is one of the key optics parameters for any accelerator. It can substantially affect the nonlinear dynamics, inﬂuencing both lifetime and the damping of instabilities, as well as affecting the ability to measure and control the linear optics. A review of published material revealed no account of coupling having been corrected signiﬁcantly below the per-mil level in any hadron accelerator. This note reports the achievement of a sub-per-mil coupling correction during an LHC Machine Development study.
RHIC spin flipper commissioning results
Bai M.; Roser, T.; Dawson, C.; Kewisch, J.; Makdisi, Y.; Oddo, P.; Pai, C.; Pile, P.
2012-05-20
The five AC dipole RHIC spin flipper design in the RHIC Blue ring was first tested during the RHIC 2012 polarized proton operation. The advantage of this design is to eliminate the vertical coherent betatron oscillations outside the spin flipper. The closure of each ac dipole vertical bump was measured with orbital response as well as spin. The effect of the rotating field on the spin motion by the spin flipper was also confirmed by measuring the suppressed resonance at Q{sub s} = 1 - Q{sub osc}.
QED effects and radiation generation in relativistic laser plasma
Kostyukov, I. Yu.; Nerush, E. N.; Bashmakov, V. F.
2011-06-01
The radiative and quantum effects in laser plasmas are discussed. The self-consistent numerical model based on particle-in-cell and Monte-Carlo methods are developed. First we analyze the spectra of Compton backscattered photons and betatron radiation in the classical and quantum regimes. Then we address an interaction between intense laser pulse and relativistic electron beam. Finally we discuss the electron-positron pair plasma production in extremely-intense laser field. It is shown that such plasma can be an efficient source of energetic gammaquanta.
Free electron laser with linearly polarized wiggler and ion channel guiding
A free electron laser (FEL) configuration utilizing a linearly polarized wiggler and ion-channel guiding has been studied for axial injection of the electron beam. The interaction results in an imperfect electron trajectory which is a superposition of two simple harmonic oscillations, one at the wiggler frequency and the other at the ion-channel frequency. The possibility of obtaining gain at the upshifted wiggler or the upshifted ion-channel betatron frequency and their odd harmonics has been shown. As a result the FEL can be tuned either by changing the electron energy or the ion-channel density
All-Optical Steering of Laser-Wakefield-Accelerated Electron Beams
We investigate the influence of a tilted laser-pulse-intensity front on laser-wakefield acceleration. Such asymmetric light pulses may be exploited to obtain control over the electron-bunch-pointing direction and in our case allowed for reproducible electron-beam steering in an all-optical way within an 8 mrad opening window with respect to the initial laser axis. We also discovered evidence of collective electron-betatron oscillations due to off-axis electron injection into the wakefield induced by a pulse-front tilt. These findings are supported by 3D particle-in-cell simulations.
Booster of laboratory of high energy
The initial design of synchrotron for acceleration of nuclei up to energy 0.5 GeV/n has been suggested. This accelerator will be used as a booster for designing the superconductive accelerator 'Nuclotron' and JINR syncrophrasotron as well. A magnetic lattice with separated functions consists of six periods and provides a betatron frequency of about 2.25. The horizontal and vertical acceptance (20 πcm x mrad) permits the multiturn injection to be realized by means of coupling resonance. (orig.)
Ghotra, Harjit Singh; Kant, Niti
2016-05-01
Electron injected in the path of a circularly polarized Gaussian laser beam under the influence of an external axial magnetic field is shown to be accelerated with a several GeV of energy in vacuum. A small angle of injection δ with 0 ∘ propagation of laser pulse is suggested for better trapping of electron in laser field and stronger betatron resonance under the influence of axial magnetic field. Such an optimized electron injection with axial magnetic field maximizes the acceleration gradient and electron energy gain with low electron scattering.
Measurements of the SPS transverse impedance in 2000
Arduini, Gianluigi; Cornelis, Karel; Klem, J T; Zimmermann, Frank; Zorzano-Mier, M P
2001-01-01
We report on measurements of coherent tune shifts, head-tail growth rates, and current-dependent betatron phase advances at the CERN SPS in the year 2000. Comparing results obtained at two different energies shows that there is no notable contribution from space charge. Within the measurement resolution the impedance is the same as in 1999, consistent with the expected small effect from changes to ony a small number of pumping ports. In 2000, data were taken over an expanded range of chromaticities, which increases the sensitivity to the impedance frequency distribution. Measuremeents of the current-dependent phase advance around the ring help localizing the most important impedance sources.
The optical design of the spin manipulation system for the SLAC Linear Collider
Fieguth, T.H.
1989-03-01
The optical design of the beam transport lines between the SLAC Linac and the electron damping ring and the design of part of the Linac lattice itself will be modified to accommodate three superconducting solenoids for the purpose of manipulating the polarization of the electron beam. In order to allow arbitrary orientation of the polarization vector, this design will be capable of compensating the fields of two independent solenoids for arbitrary strengths ranging to 7.0 T-m. The method of dealing with the coupling of the betatron functions and the method of handling both the electron and positron beams in the common region are discussed. 8 refs., 5 figs.
The optical design of the spin manipulation system for the SLAC Linear Collider
The optical design of the beam transport lines between the SLAC Linac and the electron damping ring and the design of part of the Linac lattice itself will be modified to accommodate three superconducting solenoids for the purpose of manipulating the polarization of the electron beam. In order to allow arbitrary orientation of the polarization vector, this design will be capable of compensating the fields of two independent solenoids for arbitrary strengths ranging to 7.0 T-m. The method of dealing with the coupling of the betatron functions and the method of handling both the electron and positron beams in the common region are discussed. 8 refs., 5 figs
III. Artificial sources of ionizing radiation
A theoretical explanation is given of obtaining electrons by thermal emission. The Coolidge X-ray tube is described. The spectral composition is presented of X radiation, changes in the spectrum of X radiation bremsstrahlung in dependence on anode potential and on different shapes of the rectifier of the high voltage curve. X-ray spectrography of crystals is presented as an example of the use of X radiation. Linear accelerators (simple and multiple), microtrons, cyclotrons and betatrons are used for obtaining higher energy radiation. The principle is given for each accelerator and examples of acclerators are given such as are used in clinical practice and in radiotherapy. (E.S.)
Abashkin, A.; Osipov, S.; Chakhlov, S.; Shteyn, A.
2016-06-01
The algorithm to produce primary radiographs, its transformation by dual energy method and recognition of the object materials were enhanced based on the analysis of experimental results. The experiments were carried out at the inspection complex with high X- ray source - betatron MIB 4/9 in Tomsk Polytechnic University. For the reduced X -ray dose rate, the possibility of recognition of the object materials with thickness from 20 to 120 g/cm2 was proved under the condition that as the dose rate is reduced by the defined number of times, the segment of the image fragment with the reliably identified material will increase by the same number of times.
Performance of the main ring magnet power supply of the KEK 12 GeV proton synchrotron
The main ring magnet power supply of the KEK 12 GeV PS consists of several twelve-pulse thyristor rectifiers with dc filters, of two reactive power compensators with tuned ac harmonic filters and of an analog and digital hybrid control system. In order to obtain well defined parameters-such as absolute precision of beam energy, stable beam position, tracking between focusing and bending fields to fix the betatron tune, stable acquisition of extracted beam spill etc.-one wants to operate this large pulsed power supply with high current reproducibility and low residual current ripple. In this paper, several stabilization techniques are applied in order to meet these requirements
The Long-Term Beam Losses in the CERN Injector Chain
Gilardoni, Simone; Benedetto, Elena; Damerau, Heiko; Forte, Vincenzo; Giovannozzi, Massimo; Goddard, Brennan; Hancock, Steven; Hanke, Klaus; Huschauer, Alexander; Kowalska, Magdalena; Mcateer, Meghan Jill; Metral, Elias; Mikulec, Bettina; Papaphilippou, Yannis; Rumolo, Giovanni; Sterbini, Guido; Wasef, Raymond; Arduini, Gianluigi; Meddahi, Malika; Chapochnikova, Elena
2015-01-01
For the production of the LHC type beams, but also for the high intensity ones, the budget allocated to losses in the CERN injector chain is maintained as tight as possi- ble, in particular to keep as low as possible the activation of the different machine elements. Various beam dynamics effects, like for example beam interaction with betatronic resonances, beam instabilities, but also reduced efficiency of the RF capture processes or RF noise, can produce losses even on a very long time scale. The main different mecha- nisms producing long term losses observed in the CERN injectors, and their cure or mitigation, will be revised.
Feed Forward Orbit Correction in the CLIC Ring to Main LINAC Transfer lines
Apsimon, R; Schulte, D; Uythoven, J
2014-01-01
The emittance growth in the betatron collimation system of the 27 km long transfer lines between the CLIC damping rings and the main LINAC depends strongly on the transverse orbit jitter. The resulting stability requirements of the damping ring extraction elements seem extremely difficult to achieve. Position and angle feed forward systems in these long transfer lines bring the specified parameters of the extraction elements within reach. The designs of the optics and feed forward hardware are presented together with tracking simulations of the systems.
Synergistic Laser Wakefield/Direct Laser Acceleration in the Plasma Bubble Regime
Zhang, Xi; Shvets, Gennady
2014-01-01
The concept of a hybrid laser wakefield/direct laser plasma accelerator is proposed. Relativistic electrons undergoing resonant betatron oscillations inside the plasma bubble created by a laser pulse are accelerated by gaining energy directly from the laser pulse and from its plasma wake. The resulting bifurcated phase space of self-injected plasma electrons contains a population that experiences wakefield acceleration beyond the standard one-dimensional limit because of the multi-dimensional nature of its motion that reduces the phase slippage between the electrons and the wake.
Observation of transverse instabilities in the FNAL 200 MeV Linac
McCrory, E.; Lee, G.; Webber, R.C.
1988-10-01
Using newly installed Beam Position Monitors in the downstream half of the FNAL Linac, we have observed significant transverse beam instabilities within the 30 ..mu..s beam pulse. We can affect the instability so that the peak-to-peak amplitude is as small as 0.5 mm or as large as 8 mm. The effect is largely due to a beam-plasma instability in the ten-meter 750-keV transport line. Other causes are being investigated. Using these instabilities as an analysis tool, the betatron amplitude of the beam has been reduced. 7 refs., 4 figs.
Computer simulation of the emittance growth due to noise in large hadron colliders
The problem of emittance growth due to random fluctuations of the magnetic field in a hadron collider is considered. The results of computer simulations are compared with the analytical theory developed earlier. A good agreement was found between the analytical theory predictions and the computer simulations for the collider tunes located far enough from high order betatron resonances. The dependencies of the emittance growth rate on noise spectral density, beam separation at the Interaction Point (IP) and value of beam separation at long range collisions are studied. The results are applicable to the Superconducting Super Collider (SSC)
Impact on the magnetic compressor due to CSR
LIU Chu-Yu; WANG Fang; WANG Er-Dong; QUAN Sheng-Wen; HAO Jian-Kui; LU Xiang-Yang; ZHANG Bao-Cheng; ZHAO Kui
2008-01-01
When an electron bunch is compressed in a chicane compressor,the CSR (coherent synchrotron radiation) will induce energy redistribution along the bunch.Such energy redistribution will affect the longitudinal emittance as a direct consequence.It will also excite betatron oscillation due to the chromatic transfer functions,and hence a transverse emittance change.So,it is indispensable for us to find a way to alleviate the CSR-cansed emittance dilution and the bad result of chicane compressor in PKU-FEL.
Compton scattering for spectroscopic detection of ultra-fast, high flux, broad energy range X-rays
Compton side-scattering has been used to simultaneously downshift the energy of keV to MeV energy range photons while attenuating their flux to enable single-shot, spectrally resolved, measurements of high flux X-ray sources to be undertaken. To demonstrate the technique a 1 mm thick pixelated cadmium telluride detector has been used to measure spectra of Compton side-scattered radiation from a Cobalt-60 laboratory source and a high flux, high peak brilliance X-ray source of betatron radiation from a laser-plasma wakefield accelerator
Amplitude dependent orbital period in alternating gradient accelerators
Machida, S; Edmonds, C S; Kirkman, I W; Berg, J S; Jones, J K; Muratori, B D; Garland, J M
2016-01-01
Orbital period in a ring accelerator and time of flight in a linear accelerator depend on the amplitude of betatron oscillations. The variation is negligible in ordinary particle accelerators with relatively small beam emittance. In an accelerator for large emittance beams like muons and unstable nuclei, however, this effect cannot be ignored. We measured orbital period in a linear non-scaling fixed field alternating gradient (FFAG) accelerator, which is a candidate for muon acceleration, and compared with the theoretical prediction. The good agreement between them gives important ground for the design of particle accelerators for a new generation of particle and nuclear physics experiments.
The transport of three simultaneous beams in the 1 km-length linear accelerator (linac) has been studied, from the beam recombination stage at the linac entry, to their dispersion, at the end of the linac: effects of the injection energy, the FODO mesh length and the mesh betatron propagation at the first passage, on the acceptance corresponding to the three passages, have been simulated. Optics misalignment defects and corrections have been taken into account. It appears that at least one beam position monitor per FODO mesh is necessary. The study was then extended to a two-way recirculation linac. 41 fig., 51 ref
Gamma radiography and its technological application
After the presentation of gamma radiography and X-ray radiography, the author compare both techniques showing, in particular, the greater utility of gamma radiography in industrial diagnostic and more particularly on works site diagnostic. Problem of using radiography and safety consideration will be studied. Figures shows two radiography equipment which have been designed for gamma radiography respecting the safety regulations required by the Radioisotope Inter-ministerial Commission. In the second part, different techniques and uses of gamma radiography are briefly described : xerography, neutron radiography, fluoroscopy and imaging amplifier, tomography, betatrons and linear accelerators. Cost analysis will discussed in conclusion. (M.P.)
ARTUS: THE TUNE MEASUREMENT SYSTEM AT RHIC
DREES,A.; BRENNAN,M.; CONNOLLY,R.; MICHNOFF,R.; DELONG,J.
2000-05-08
The super-conducting Relativistic Heavy Ion Collider (RHIC) with two separate rings and six combined interaction regions will provide collisions between equal and unequal heavy ion species up to Au ions in typically 60 bunches. The betatron tunes of the two beams are among the most important parameters to be measured. The tunes have to be acquired at any moment during accelerator operation and in particular during the acceleration process. At RHIC the tune measurement device (ARTUS) consists of a fast horizontal and vertical kicker magnet and a dedicated beam position monitor in each ring. The system layout is described and first experiences from operation is reported.
Computer programs in accelerator physics
Three areas of accelerator physics are discussed in which computer programs have been applied with much success: i) single-particle beam dynamics in circular machines, i.e. the design and matching of machine lattices; ii) computations of electromagnetic fields in RF cavities and similar objects, useful for the design of RF cavities and for the calculation of wake fields; iii) simulation of betatron and synchrotron oscillations in a machine with non-linear elements, e.g. sextupoles, and of bunch lengthening due to longitudinal wake fields. (orig.)
Laser wakefield accelerator based light sources: potential applications and requirements
In this article we review the prospects of laser wakefield accelerators as next generation light sources for applications. This work arose as a result of discussions held at the 2013 Laser Plasma Accelerators Workshop. X-ray phase contrast imaging, X-ray absorption spectroscopy, and nuclear resonance fluorescence are highlighted as potential applications for laser-plasma based light sources. We discuss ongoing and future efforts to improve the properties of radiation from plasma betatron emission and Compton scattering using laser wakefield accelerators for these specific applications.
Longitudinal reshaping of bunches in the U-70 synchrotron via RF noise gymnastics
Changing form of bunches at the U-70 synchrotron is required for the lowering peak density of beam and increasing Coulomb shift of betatron frequency on the plateau of input. Longitudinal noise swinging based on the introduction of controlled phase noise in accelerating PF voltage is designed for it. Experimental test of noise gymnastic principle on the plateau of input is performed. Beam measurements confirming efficiency of the method are conducted; technical description of the noise swinging pilot plant is performed. Experimental data resulting from its tests are given, and its comparison with calculated results is conducted
Seismic surveying and accelerators
The paper deals with an investigation into the impact of earth vibrations on charged particle beams in modern colliders. It is ascertained that the displacement of accelerator magnetic elements from the perfect position results in the excitation of betatron oscillations and distortion of particle orbit position. The results of experimental investigations into seismic noises are presented for ASR, SSC, DESY and KEK. The rms orbit displacement in accelerators is estimated relying on the law of earth diffusion motion, according to which the variance of relative displacements is proportional to the distance between these points and time of observation. 6 refs., 3 figs., 2 tabs
Study on CSR in storage ring and ERL
A fine dip structure can be made in the long electron bunch by the technique so called 'laser bunch slicing'. At the UVSOR-II storage ring, the oscillation of the dip structure related to the betatron tune was observed in some low alpha optics. It indicated the existence of the transverse-longitudinal coupling effect, which had been theoretically predicted. Additionally, an inverse Compton scattering of coherent synchrotron radiation is proposed as a soft X-ray source of 200 MeV class energy recovery linac (ERL). The light source has a sub pico-seconds short pulse with high repetition rate of 1.3 GHz. (author)
Multibunch feedback---Strategy, technology, and implementation options
The proposed next generation accelerator and synchrotron light facilities will require active feedback systems to control multi-bunch instabilities. These feedback systems must operate in machines with thousands of circulating bunches and with short (2--4 ns) interbunch intervals. The functional requirements for transferse (betatron) and longitudinal (synchrotron) feedback systems are presented. Several possible implementation options are discussed and system requirements developed. Results are presented from a digital signal processing based synchrotron oscillation damper operating at the SSRL/SLAC SPEAR storage ring
Searching for the Optimal Working Point of the MEIC at JLab Using an Evolutionary Algorithm
The Medium-energy Electron Ion Collider (MEIC), a proposed medium-energy ring-ring electron-ion collider based on CEBAF at Jefferson Lab. The collider luminosity and stability are sensitive to the choice of a working point - the betatron and synchrotron tunes of the two colliding beams. Therefore, a careful selection of the working point is essential for stable operation of the collider, as well as for achieving high luminosity. Here we describe a novel approach for locating an optimal working point based on evolutionary algorithm techniques.
Ion shaking in the 200 MeV XLS-ring
Ions, trapped inside the beam's potential, can be removed by the clearing electrodes when the amplitude of the ion oscillation is increased by vertically shaking the ions. A similar experiment in the 200 MeV XLS ring is described. In the experiments, RF voltage was applied on a pair of vertical striplines. The frequency was scanned in the range of the ion (from H2 to CO2) bounce frequencies in the ring (1-10 MHz). The response of the beam size, vertical betatron tune and lifetime was studied. (author) 19 refs.; 4 figs