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Coherent instability and ion trapping considerations for Aladdin lattices

Description: This paper presents the results of an investigation of the effects of ions and coherent collective instabilities on bunched electron beams circulating in the various Aladdin lattices considered in the Aladdin Upgrade Study. It is aimed particularly at identifying those collective and ion phenomena that may be limiting the performance of the present Aladdin with low energy (100 MeV) injection, at ascertaining which of these phenomena would still remain and limit the performance with a full energy (800 MeV) injector for any correction schemes (either active or passive) to alleviate the performance impact of these phenomena; overview of the behavior at low and high energy (and current), the dependence of this behavior on the rf frequency, and the resulting implications for the upgraded Aladdin operations will emerge in the course of this report. 12 refs., 11 figs., 5 tabs.
Date: May 1, 1985
Creator: Chattopadhyay, S.
Partner: UNT Libraries Government Documents Department

Structural analysis of equilibrium and ohmic heating coil assemblies for the TFTR

Description: The structural adequacy of the equilibrium and ohmic heating coils and their support systems for the TFTR device has been investigated. The capability of the coils to span ribs of the support structure has been established. The support structure has been found to be effective in resisting the magnetic forces in the coils. The bands encircling the outboard coils and the band tensioning devices have been found to perform adequately. The analysis is based on October 1975 conceptual design.
Date: October 1, 1975
Creator: Chattopadhyay, S.
Partner: UNT Libraries Government Documents Department

Physics and design issues of asymmetric storage ring colliders as B-factories

Description: This paper concentrates on generic R D and design issues of asymmetric colliders via a specific example, namely a 9 GeV {times} 3 GeV collider based on PEP at SLAC. An asymmetric e{sup +}-e{sup -} collider at the Y(4s) and with sufficiently high luminosity (10{sup 33}-10{sup 34} cm{sup -2} s{sup -1}) offers the possibility of studying mixing, rare decays, and CP violation in the B{bar B} meson system, as well as beautiful'' tau-charm physics, and has certain qualitative advantages from detection and machine design points of view. These include: the energy constraint; clean environment ({approximately}25% B{sup +}B{sup -}, B{sup 0}{bar B}{sup 0}); large cross section (1 nb); vertex reconstruction (from the time development of space-time separated B and {bar B} decays due to moving center-of-mass); reduced backgrounds; greatest sensitivity to CP violation in B {yields} CP eigenstate; the possibility of using higher collision frequencies, up to 100 MHz, in a head-on colliding mode using magnetic separation. It is estimated that for B {yields} {Psi}K{sub s}, an asymmetric collider has an advantage equivalent to a factor of five in luminosity relative to a symmetric one. There are, however, questions with regard to the physics of the asymmetric beam-beam coulomb interaction that may limit the intrinsic luminosity and the possibility of realizing the small beam pipes necessary to determine the vertices. 16 refs., 2 figs.
Date: August 1, 1989
Creator: Chattopadhyay, S.
Partner: UNT Libraries Government Documents Department

Advances in beam physics and technology: Colliders of the future

Description: Beams may be viewed as directed and focussed flow of energy and information, carried by particles and electromagnetic radiation fields (ie, photons). Often, they interact with each other (eg, in high energy colliders) or with other forms of matter (eg, in fixed targets, sychrotron radiation, neutron scattering, laser chemistry/physics, medical therapy, etc.). The whole art and science of beams revolve around the fundamental quest for, and ultimate implementation of, mechanisms of production, storage, control and observation of beams -- always directed towards studies of the basic structures and processes of the natural world and various practical applications. Tremendous progress has been made in all aspects of beam physics and technology in the last decades -- nonlinear dynamics, superconducting magnets and rf cavities, beam instrumentation and control, novel concepts and collider praradigms, to name a few. We illustrate this progress with a few examples and remark on the emergence of new collider scenarios where some of these progress might come to use -- the Gamma-Gamma Collider, the Muon Collider, laser acceleration, etc. We close with an outline of future oppotunities and outlook.
Date: November 1, 1994
Creator: Chattopadhyay, S.
Partner: UNT Libraries Government Documents Department

Beam Dynamics Activities and Plans at LBL

Description: On-going beam dynamics studies at LBL are performed in connection with the 1-2 GeV Advanced Light Source (ALS), the SSC, Collider Physics (Novel Power Sources) and Heavy Ion Fusion Accelerator Research (HIFAR). Exploratory activities include generic research on (a) high-brightness, low-emittance storage rings and linacs for the TeV-scale future linear colliders, b{bar b} facilities, etc., (b) beam dynamics and optics of incoherent and coherent undulator radiation, (c) Free Electron Laser Studies, (d) development of a high-brightness laser-driven RF photocathode electron source for the LBL-LLNL-SLAC collaboration on Relativistic Klystrons and (e) new methods of acceleration. The major physics issues being studied in connection with the ALS are the effects of undulators and wigglers on storage ring beam dynamics (nonlinear stability and stable dynamic aperture), short bunch-length collective phenomena and multi-loop high-fidelity orbit and photon beam feedback for stability of the radiation source. In connection with the first issue, detailed nonlinear behavior of the electron beam in presence of insertion devices in an otherwise symmetric low-emittance lattice are being pursued and various compensation schemes are being investigated. We held a workshop on this specialized topic May 17-20, 1988 at LBL, where participants from international laboratories such as Sincrotrone Trieste, KEK, SLAC, BNL, ANL, etc., participated. Contributions will soon be published as proceedings to this workshop. Considerable insight into the physics of short bunches has been gained through a similar workshop last year on the 'Impedance Beyond Cutoff' at LBL, where a realistic picture of the impedance spectrum at high frequencies corresponding to short bunch lengths emerged. The focus at the moment is on the nature of coherent instabilities potentially driven by this high-frequency impedance. Securing a stable photon beam against vibrations and other noise sources simultaneously at several beam lines in a synchrotron radiation source is nontrivial and requires multi-loop orbit feedback ...
Date: July 1, 1988
Creator: Chattopadhyay, S.
Partner: UNT Libraries Government Documents Department

Plasma lens experiments at the final focus test beam

Description: The authors intend to carry out a series of plasma lens experiments at the Final Focus Test Beam facility at SLAC. These experiments will be the first to study the focusing of particle beams by plasma focusing devices in the parameter regime of interest for high energy colliders, and is expected to lead to plasma lens designs capable of unprecedented spot sizes. Plasma focusing of positron beams will be attempted for the first time. They will study the effects of lens aberrations due to various lens imperfections. Several approaches will be applied to create the plasma required including laser ionization and beam induced tunneling ionization of a working gas--the latter which has never been observed before. The compactness of the device should prove to be of interest for applications at the SLC and the next generation linear colliders.
Date: February 1, 1995
Creator: Barletta, W.; Chattopadhyay, S. & Chen, P.
Partner: UNT Libraries Government Documents Department

Photon-Electron Interaction and Condense Beams

Description: We discuss beams of charged particles and radiation from multiple perspectives. These include fundamental acceleration and radiation mechanisms, underlying electron-photon interaction, various classical and quantum phase-space concepts and fluctuational interpretations.
Date: November 1, 1998
Creator: Chattopadhyay, S.
Partner: UNT Libraries Government Documents Department

Simulation of synchrotron motion with rf noise

Description: The theoretical formulation is described that is behind an algorithm for synchrotron phase-space tracking with rf noise and some preliminary simulation results of bunch diffusion under rf noise obtained by actual tracking.
Date: August 1, 1986
Creator: Leemann, B.T.; Forest, E. & Chattopadhyay, S.
Partner: UNT Libraries Government Documents Department

Generation of Femtosecond X-Rays by 90 degrees Compton Scattering

Description: We propose Compton scattering of a short pulse visible laser beam by a low energy (but relativistic) electron beam at a right angle for generation of femtosecond x-rays. Simple analysis to determine the qualitative and quantitative characteristics of the x-ray pulse is presented.
Date: December 1, 1992
Creator: Kim, K.-J.; Chattopadhyay, S. & Shank, C.V.
Partner: UNT Libraries Government Documents Department

Study on a test of optical stochastic cooling scheme in a single pass beam line

Description: A feasibility study of an experiment to test the principle of optical stochastic cooling is presented. We propose to build a new beamline in the extraction area of the ALS Booster synchrotron, where we will include a bypass lattice similar to the lattice that could be used in the cooling insertion in a storage ring. Of course, in the single pass beamline we cannot achieve cooling, but we can test all the functions of the bypass lattice that are required to achieve cooling in a storage ring. As it is stated in, there are stringent requirements on the time-of-flight properties of the bypass lattice employed in a cooling scheme. The pathlengths of particle trajectories in the bypass must be fairly insensitive to the standard set of errors that usually affect the performance of storage rings. Namely, it is necessary to preserve all fluctuations in the longitudinal particle density within the beam from the beginning to the end of the bypass lattice with the accuracy of {lambda}/2{pi}, where A is the carrying (optical) wavelength. According to, cooling will completely vanish if a combined effect of all kinds of errors will produce a spread of the pathlengths of particle trajectories larger than {lambda}/2 and the cooling time will almost double if the spread of the pathlengths is {lambda}/2{pi}. At a first glance, {lambda}/2{pi} {approx_equal} 0.1/{mu}m is such a small value that satisfying this accuracy looks nearly impossible. However, simulations show that a carefully designed bypass can meet all the requirements even with rather conservative tolerance to errors.
Date: January 1997
Creator: Chattopadhyay, S.; Kim, C.; Massoletti, D. & Zholents, A.
Partner: UNT Libraries Government Documents Department

Halo particle confinement in the VLHC using optical stochastic cooling

Description: Beam halo particles following the extreme trajectories near the physical aperture limit radiate Smith-Purcell radiation when moving over a diffraction grating. This grating can be used as a pick-up and a kicker for optical stochastic cooling of the halo particles. In this application cooling would have the effect of slowing down the halo particle diffusion onto the aperture. Cooling efficiency would quickly diminish with the distance from the aperture and would only affect the halo particles. A preliminary analysis of this system is considered.
Date: June 1, 2000
Creator: Zholents, Alexander; Barletta, W.; Chattopadhyay, S. & Zolotorev, M.
Partner: UNT Libraries Government Documents Department


Description: Conceptual design of a bright electron injector for the 1 GeV high gradient test experiment. envisaged by the LLNL-SLAC-LBL collaboration on the Relativistic Klystron is presented. The design utilizes a high-brightness laser-driven RF photocathode electron gun, similar to the pioneering LANL early studies in concept (different parametrically however), together with achromatic magnetic bunching and transport systems and diagnostics. The design is performed with attention to possible use in an FEL as well. A simple but realistic analytic model including longitudinal and transverse space-charge and RF effects and extensive computer simulation form the basis of the parametric choice for the source. These parameters are used as guides for the design of the pico-second laser system and magnetic bunching section.
Date: September 1, 1988
Creator: Chattopadhyay, S.; Chen, Y.J.; Hopkins, D.; Kim, K.J.; Kung, A.; Miller, R. et al.
Partner: UNT Libraries Government Documents Department

Femtosecond X-rays from 90{degree} Thomson scattering

Description: The authors report on progress on the femtosecond X-ray pulse generation experiment. The experiment involves a relativistic electron beam (50 MeV) with an rms bunch length of 10 ps containing 1--2 nC of charge, and a ultrashort pulse (50--200 fs), high power (< 4 TW) 0.8 {micro}m laser beam from a Ti:Al{sub 2}O{sub 3} laser system. Both beams are focused down to about a 50 {micro}m waist size and intersect at 90{degree}. The laser field acts as an electromagnetic undulator for the relativistic electron beam generating radiation upshifted by 2 {gamma}{sup 2} and a pulse length given by the transit time of the laser beam across the electron beam. For a 50 MeV electron beam they expect 10{sup 5} photons at 0.4 {angstrom} (25% bandwidth) in a cone angle of 6--10 mrad in about a 200 fs pulse.
Date: April 1, 1995
Creator: Leemans, W.; Schoenlein, R.; Chin, A.; Glover, E.; Govil, R.; Volfbeyn, P. et al.
Partner: UNT Libraries Government Documents Department

Design concepts of a storage ring for a high power XUV free electron laser

Description: The study of a storage ring capable of sustaining an electron beam of the quality required for a High Gain Free Electron Laser in the vacuum ultraviolet and x-ray region is reported. A method is described for the optimization of the design of the storage ring, where several competing and often conflicting requirements come into play. An example design is presented of a ring that satisfies the required conditions of beam quality and is able to produce coherent radiation at 400 A with tens of megawatts of peak power.
Date: August 1, 1985
Creator: Cornacchia, M.; Bisognano, J.; Chattopadhyay, S.; Garren, A.; Halbach, K.; Jackson, A. et al.
Partner: UNT Libraries Government Documents Department

Design of a relativistic Klystron Two-Beam Accelerator Prototype

Description: We are designing an experiment to study physics, engineering, and costing issues of an extended Relativistic Klystron Two-Beam Accelerator (RK-TBA). The experiment is a prototype for an RK-TBA based microwave power source suitable for driving a 1 TeV linear collider. Major components of the experiment include a 2.5-MV, 1.5-kA electron source, a 11.4-GHz modulator, a bunch compressor, and a 8-m extraction section. The extraction section will be comprised of 4 traveling-wave output structures, each generating about 360 MW of rf power. Induction cells will be used in the extraction section to maintain the average beam energy at 5 MeV. Status of the design is presented.
Date: April 1, 1995
Creator: Westenskow, G.; Caporaso, G.; Chen, Y.; Houck, T.; Yu, S.; Chattopadhyay, S. et al.
Partner: UNT Libraries Government Documents Department

An Asymmetric B-Meson Factory at PEP

Description: A preliminary design for a B-factory has been made using asymmetric collisions between positrons in the PEP storage ring and electrons in a new, low-energy ring. The design utilizes small-aperture, permanent-magnet quadrupoles close to the interaction point (IP). Optimization of optical and beam parameters at the IP will be discussed, as well as the lattice design of the interaction region and of the rings.
Date: January 1, 1990
Creator: Garren, A.A.; Chattopadhyay, S.; Chin, Y.; Oddone, P.J.; Zisman, Michael S.; Donald, M. et al.
Partner: UNT Libraries Government Documents Department

Comparison of EXAFS Foil Spectra from Around the World

Description: The EXAFS spectra of Cu and Pd foil from many different beamlines and synchrotrons are compared to address the dependence of the amplitude reduction factor (S{sub 0}{sup 2}) on beamline specific parameters. Even though S{sub 0}{sup 2} is the same parameter as the EXAFS coordination number, the value for S{sub 0}{sup 2} is given little attention, and is often unreported. The S{sub 0}{sup 2} often differs for the same material due to beamline and sample attributes, such that no importance is given to S{sub 0}{sup 2}-values within a general range of 0.7 to 1.1. EXAFS beamlines have evolved such that it should now be feasible to use standard S{sub 0}{sup 2} values for all EXAFS measurements of a specific elemental environment. This would allow for the determination of the imaginary energy (Ei) to account for broadening of the EXAFS signal rather than folding these errors into an effective S{sub 0}{sup 2}-value. To test this concept, we model 11 Cu-foil and 6 Pd-foil EXAFS spectra from around the world to compare the difference in S{sub 0}{sup 2}- and Ei-values.
Date: July 16, 2010
Creator: Kelly, S. D.; Bare, S. R.; Greenlay, N.; Azevedo, G.; Balasubramanian, M.; Barton, D. et al.
Partner: UNT Libraries Government Documents Department

Measurements of Radiation Near An Atomic Spectral Line From the Interaction of a 30-GeV Electron Beam And a Long Plasma

Description: Emissions produced or initiated by a 30 GeV electron beam propagating through a {approx}1 m long heat pipe oven containing neutral and partially ionized vapor have been measured near atomic spectral lines in a beam-plasma wakefield experiment. The Cerenkov spatial profile has been studied as a function of oven temperature and pressure, observation wavelength, and ionizing laser intensity and delay. The Cerenkov peak angle is affected by the creation of plasma; estimates of plasma and neutral density have been extracted. Increases in visible background radiation consistent with increased plasma recombination emissions due to dissipation of wakefields were simultaneously measured.
Date: September 12, 2005
Creator: Catravas, P.; Chattopadhyay, S.; Esarey, E.; Leemans, W.P.; /LBL, Berkeley; Assmann, R. et al.
Partner: UNT Libraries Government Documents Department

Plasma density from Cerenkov radiation, betatron oscillations, and beam steering in a plasma wakefield experiment at 30 GeV

Description: A method for using Cerenkov radiation near atomic spectral lines to measure plasma source properties for plasma wakefield applications has been discussed and experimentally verified. Because the radiation co-propagates with the electron beam, the radiation samples the source properties exactly along the path of interest with perfect temporal synchronization. Observation wavelengths were chosen with respect to the atomic resonances of the plasma source, where the relative change in the index of refraction strongly affects the Cerenkov cone angle, and permits flexible diagnostic design. The Cerenkov spatial profiles were systematically studied for a Lithium heat pipe oven as a function of oven temperature and observation wavelength. Neutral densities and plasma densities were extracted from the measurements.
Date: January 1, 2001
Creator: Catravas, P.; Chattopadhyay, S.; Esarey, E.; Leemans, W.P.; Assmann, R.; Decker, F.-J. et al.
Partner: UNT Libraries Government Documents Department

Transverse envelope dynamics of a 28.5 GeV electron beam in a long plasma

Description: The transverse dynamics of a 28.5 GeV electron beam propagating in a 1.4 m long, 0-2 x 10{sup 14} cm{sup -3} plasma are studied experimentally in the underdense or blow-out regime. The transverse component of the wake field excited by the short electron bunch focuses the bunch, which experiences multiple betatron oscillations as the plasma density is increased. The spot size variations are observed using optical transition radiation and Cherenkov radiation. In this regime, the behavior of the spot size as a function of the plasma density is well described by a simple beam envelope model. Dynamic changes of the beam envelope are observed by time resolving the Cherenkov light.
Date: April 1, 2002
Creator: Clayton, C.E.; Blue, B.E.; Dodd, E.S.; Joshi, C.; Marsh, K.A.; Mori, W.B. et al.
Partner: UNT Libraries Government Documents Department