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1. 5 GeV/c multiturn shaving extraction and its transport line for the Brookhaven AGS

Description: A system for fast shaving extraction at 1.5 GeV/c is implemented to extract the circulating beam in five turns. A numerical simulation is first carried out to determine the emittance and the rf structure of the extracted beam. This is followed by several machine study sessions which establish the optimal extraction configuration, confirm the emittance, and modify the transport line for low energy beam. Finally, a one-week run for the Neutrino Oscillation experiment demonstrates that the system is very stable and capable of delivering 7.5 x 10/sup 12/ p/sec with 70% extraction efficiency and 95% transport efficiency.
Date: January 1, 1979
Creator: Weng, W.T.; Blumberg, L.N.; Gill, E.; Soukas, A.; Witkover, R.L.; Egleman, E. et al.
Partner: UNT Libraries Government Documents Department

Beam transfer from the AGS to ISABELLE

Description: The ISABELLE design current is built up by repetitive transfer of charge from the AGS. To do this, a momentum stacking method similar to the one used at the ISR has been chosen. The AGS beam bunches are synchronously transferred from the AGS into waiting rf buckets on the injection orbit at the ISA, and then slowly accelerated into the previously established debunched beam stack. This process is repeated until all the available momentum aperture in the ISA is filled up, whereupon the beam stack is rebunched and accelerated to the desired operating energy.
Date: January 1, 1979
Creator: Weng, W.T.; Brown, H.; Claus, J.; Foelsche, H.; Lee, Y.Y. & Raka, E.
Partner: UNT Libraries Government Documents Department

New AGS fast extraction system

Description: Both the high energy physics program and ISA injection require an improved fast extraction system from the AGS. The proposed new system consists of a fast kicker at H5 and an ejector magnet at H10. The H5 kicker is capable of producing 1.2 mrad deflection and rising up to 99% strength in 150 nsec with flat top ripple within +- 1%. It is found that the focusing strengths and positions of UQ3-UQ7 have to be modified to achieve an achromatic condition at the end of 8/sup 0/-bend. Also, the conceptual design of the H5 magnet and the pulser system are discussed.
Date: September 1, 1980
Creator: Weng, W.T.
Partner: UNT Libraries Government Documents Department

Introduction to the magnet and vacuum systems of an electron storage ring

Description: An accelerator or storage ring complex is a concerted interplay of various functional systems. For the convenience of discussion we can divide it into the following systems: injector, magnet, RF, vacuum, instrumentation and control. In addition, the conventional construction of the building and radiation safety consideration are also needed and finally the beam lines, detector, data acquisition and analysis set-ups for research programs. Dr. L. Teng has given a comprehensive review of the whole complex and the operation of such a facility. I concentrate on the description of magnet and vacuum systems. Only the general function of each system and the basic design concepts will be introduced, no detailed engineering practice will be given which will be best done after a machine design is produced. For further understanding and references a table of bibliography is provided at the end of the paper.
Date: August 15, 1982
Creator: Weng, W.T.
Partner: UNT Libraries Government Documents Department

AGS new fast extraction system and the single bunch extraction test

Description: For the neutrino physics program and for the CBA injection, a new fast extraction system has been implemented to improve the extraction efficiency and the quality of the extracted beam. Central to the new system is a new fast kicker, placed at the H5 straight section, capable of rising between bunches, t/sub r/ < 170 nsec, and staying constant for 2.6 ..mu..sec with flat top ripple less than +-1.5%. So far, the system has been operated for longer than 3000 hours and routinely extracts 10/sup 13/ ppp at 99% efficiency. Experiment 745 on QCD test requires a single AGS bunch of 40 nsec. For this purpose another fast kicker was placed at the E5 straight section and powered by a new pulser to produce a half sinusoidal pulse with both a rise and fall time of 200 nsec. A single AGS bunch was extracted through the slow beam channel at 22 GeV/c leaving the remaining 11 bunches undisturbed which continued to be accelerated to 29.4 GeV/c and extracted by the H5 kicker through the fast beam channel. Because the ring circumference ratio of CBA to the AGS is 4-3/4, some of the injected beam from the AGS has to contain 11 bunches instead of 12; consequently, this single bunch extraction mode will also be used for CBA injection.
Date: January 1, 1983
Creator: Weng, W.T.
Partner: UNT Libraries Government Documents Department

Lattice design and tolerance analysis of the CBA transport line

Description: The beam transport line from the AGS to CBA is 600 m long and consists of 70 bending magnets and 20 quadrupoles, as well as several special injection components. The beam has to bend 117/sup 0/ horizontally and drop 1.8 m in elevation. To insure that it has momentum acceptance of ..delta..P/P = +-1% and the transverse emittance dilution is within 30%, a detailed tolerance analysis has been carried out on the requirements of the AGS beam properties, magnetic field quality of the transport magnets, and misalignment errors. Field quality tolerances of ..delta..B/sub 0//B less than or equal to 1 x 10/sup -3/ for bending field, ..delta.. G/G less than or equal to 5 x 10/sup -3/ for gradient field, and ..delta..B/sub 2//B less than or equal to 2.5 x 10/sup -4/ cm/sup -2/ of the sextupole components in the bending magnets are indicated.
Date: January 1, 1983
Creator: Weng, W.T.
Partner: UNT Libraries Government Documents Department

Multiwire secondary-emission monitor and the emittance measurement of the AGS beam

Description: For CBA injection the transverse emittances and the Twiss parameters of the AGS beam have to be well defined to minimize the phase space dilution in CBA. Althoug there exists a profile monitor device at U165, there are three reasons why construction of multiwire profile monitor system at three locations from U500 to U168 is required: (1) the dispersion function is not zero at U165 which makes it harder to interpret the measurement; (2) the original single wire device takes five minutes to traverse the whole beam; (3) a three station multiwire system can provide the profile information at all locations in one pulse which makes on-line analysis possible. In summary, a set of three stations of Multiwire Secondary Emission Monitor (MSEM) has been built and installed in the fast external beam line for the measurement of beam profiles. Each unit consists of two planes each with 30 nickel wires having a diameter of 5 mils. The signal is linear within the range of 10/sup 10/ to 10/sup 13/ incident protons on the wire and the resolution of the signal is well within a few percent. A least-square fitting routine has been used to extract the emittance and phase space parameters of the beam. The emittances obtained at various intensities will help us to understand the AGS acceleration process and to choose the optimal injection scheme for CBA.
Date: January 1, 1983
Creator: Weng, W.T.; Chiang, I.H.; Smith, G.A. & Soukas, A.
Partner: UNT Libraries Government Documents Department

Resonance behavior in the presence of space charge

Description: An analysis is presented of the resonance behavior of particle beams in the presence of space charge fields. Since self-consistent requirements are ignored, the results describe onset or early behavior. It is shown that in a beam of uniform current resonances excited by magnetic field errors are stabilized by the detuning effect of the self-field space charge force. This situation is changed when a radiofrequency accelerating field is applied. As beam bunching results after rf turn-on, the space charge force becomes modulated along the bunches, vanishing at the ends. At these regions of small or vanishing space charge, stabilization from non-linear detuning tends to disappear, thus leaving particles susceptible to resonance blow-up. This picture of the effect of beam bunching can be studied by considering the phase space structure for particles at different positions along the bunches. A somewhat unusual conclusion is made on the use of this analysis to model beam capture in a synchrotron at low energy.
Date: January 1, 1983
Creator: Month, M. & Weng, W.T.
Partner: UNT Libraries Government Documents Department

Hadron-hadron colliders

Description: The objective is to investigate whether existing technology might be extrapolated to provide the conceptual framework for a major hadron-hadron collider facility for high energy physics experimentation for the remainder of this century. One contribution to this large effort is to formalize the methods and mathematical tools necessary. In this report, the main purpose is to introduce the student to basic design procedures. From these follow the fundamental characteristics of the facility: its performance capability, its size, and the nature and operating requirements on the accelerator components, and with this knowledge, we can determine the technology and resources needed to build the new facility.
Date: June 21, 1983
Creator: Month, M. & Weng, W.T.
Partner: UNT Libraries Government Documents Department

Forces on the conductors of the Arc AG Magnet

Description: In the evaluation of the design of the support system for the Arc AG Magnets, factors which could deform or move the magnet have to be considered. Typically they are the ground movements, temperature effects, water vibrations, magnetic forces on the magnet and coil, and accidental human or equipment impacts. This note calculates the magnetic forces on the conductors at an excitation for a 50 GeV beam. It is found that the force is not negligible; therefore, a method to restrict the movement of the conductors should be introduced.
Date: December 28, 1983
Creator: Weng, W.T.
Partner: UNT Libraries Government Documents Department

Stability in dynamical systems I

Description: We have reviewed some of the basic techniques which can be used to analyze stability in nonlinear dynamical systems, particularly in circular particle accelerators. We have concentrated on one-dimensional systems in the examples in order to simply illustrate the general techniques. We began with a review of Hamiltonian dynamics and canonical transformations. We then reviewed linear equations with periodic coefficients using the basic techniques from accelerator theory. To handle nonlinear terms we developed a canonical perturbation theory. From this we calculated invariants and the amplitude dependence of the frequency. This led us to resonances. We studied the cubic resonance in detail by using a rotating coordinate system in phase space. We then considered a general isolated nonlinear resonance. In this case we calculated the width of the resonance and estimated the spacing of resonances in order to use the Chirikov criterion to restrict the validity of the analysis. Finally the resonance equation was reduced to the pendulum equation, and we examined the motion on a separatrix. This brought us to the beginnings of stochastic behavior in the neighborhood of the separatrix. It is this complex behavior in the neighborhood of the separatrix which causes the perturbation theory used here to diverge in many cases. In spite of this the methods developed here have been and are used quite successfully to study nonlinear effects in nearly integrable systems. When used with caution and in conjunction with numerical work they give tremendous insight into the nature of the phase space structure and the stability of nonlinear differential equations. 14 references.
Date: August 1, 1984
Creator: Courant, E.D.; Ruth, R.D. & Weng, W.T.
Partner: UNT Libraries Government Documents Department

Vibrational modes of the pedestal support system for the SLC Arc magnets

Description: The magnet support system for the SLC Arcs will be a long series of pedestals with each pedestal supporting the ends of two adjacent magnets. It has been pointed out by several authors that random magnet vibrations in the Arc with amplitudes larger than 0.1 ..mu..m rms are potentially harmful for the SLC operation. In order to assess the vibrational behavior of the Arc magnet system, we need to understand: (1) the sources and characteristics of the ground disturbances, (2) the coupled vibrational modes of the composite pedestal-magnet system and, (3) the response of the system to ground disturbance.
Date: October 1, 1984
Creator: Weng, W.T. & Chao, A.W.
Partner: UNT Libraries Government Documents Department

Nonlinear beam-beam resonances

Description: Head-on collisions of bunched beams are considered, assuming the two colliding beams have opposite charges. A few experimental observations are described. The single resonance analysis is developed that is applicable to the strong-weak case of the beam-beam interaction. In this case, the strong beam is unperturbed by the beam-beam interaction; motions of the weak beam particles are then analyzed in the presence of the nonlinear electromagnetic force produced by the strong beam at the collision points. The coherent motions of the two coupled strong beams are shown to exhibit distinct nonlinear resonance behavior. 16 refs., 22 figs. (LEW)
Date: January 1, 1985
Creator: Chao, A.W.; Bambade, P. & Weng, W.T.
Partner: UNT Libraries Government Documents Department

Coupled vibrational modes of the SLC Arc magnet and support system

Description: The magnet support system for the SLC Arcs will be a long series of pedestals with each pedestal supporting the ends of two adjacent magnets. It has been pointed out by several authors that random magnet vibrations in the Arc with amplitudes larger than 0.1 ..mu..m rms are potentially harmful for the SLC operation. In order to assess the vibrational behavior of the Arc magnet system, we need to understand: (1) the sources and characteristics of the ground disturbances, (2) the coupled vibrational modes of the composite pedestal-magnet system, and (3) the response of the system to ground disturbance. This note is an attempt to study item (2). 5 refs., 4 figs., 1 tab.
Date: March 1, 1985
Creator: Weng, W.T. & Chao, A.W.
Partner: UNT Libraries Government Documents Department

SLC Arc transport system: AG-magnet measurement and performance

Description: This paper describes the design, construction, and operation of devices used to rapidly measure the mechanical and magnetic properties of some 950 Alternate gradient magnets used in the arc system of the Stanford Linear Collider. The problems of dealing with the measurement of the transverse dimensions to within minute (0.0001 in.) resolution of objects that are 8 ft long are discussed. Early results from the production runs of these magnets are presented. 7 refs., 6 figs.
Date: March 1, 1985
Creator: Weng, W.T.; Anderson, M.; Byers, R.; Cobb, J.; Fischer, G. & Hamilton, V.
Partner: UNT Libraries Government Documents Department

Nomenclature of SLC Arc beamline components

Description: This note defines I and C formal names for beamline components in the Arc as specified in the TRANSPORT decks ARCN FINAL and ARCS FINAL of June 5, 1985. The formal name consists of three fields: the primary name, the zone and the unit number. The general principles and guidelines are explained in Reference 1. The rationale and the final resolutions of the naming conventions for the Arc are explained.
Date: April 10, 1986
Creator: Silva, J. & Weng, W.T.
Partner: UNT Libraries Government Documents Department

Space charge effects: tune shifts and resonances

Description: The effects of space charge and beam-beam interactions on single particle motion in the transverse degree of freedom are considered. The space charge force and the resulting incoherent tune shift are described, and examples are given from the AGS and CERN's PSB. Equations of motion are given for resonances in the presence of the space charge force, and particle behavior is examined under resonance and space charge conditions. Resonance phase space structure is described with and without space charge. Uniform and bunched beams are compared. Beam-beam forces and resonances and beam-beam detuning are described. 18 refs., 15 figs. (LEW)
Date: August 1, 1986
Creator: Weng, W.T.
Partner: UNT Libraries Government Documents Department

Analysis of optical perturbations of the SLC arcs

Description: This paper establishes the analytical framework in solving optical pertubations in a transport line in general and the SLC Arc specifically. The Formulation presented here is applicable to any transport system in a straightforward way. The equations of motion of a perturbed betatron function and dispersion function are presented. Sources of field errors for the SLC Arc system are discussed. Magnitudes of pertubations to the optical functions for the SLC Arc are estimated. (JDH)
Date: January 1, 1987
Creator: Weng, W.T. & Sands, M.
Partner: UNT Libraries Government Documents Department

Analysis of orbit perturbations of the SLC arcs

Description: The generation and correction of orbit errors are analyzed. A general stability criterion for the orbit correction is established and the rms orbit errors and corrector strengths are calculated. The formulation is then applied to the design of the Stanford Linear Collider to obtain estimates for residual orbit distortion after correction. (LEW)
Date: January 1, 1987
Creator: Weng, W.T.; Murray, J. & Chao, A.
Partner: UNT Libraries Government Documents Department

Some experiences from the commissioning program of the SLC arcs

Description: The SLC Arc System is designed to transport beams of electrons and positrons from the end of the SLAC Linac to the beginning of the Final Focus System where they are made to collide head on. To minimize phase space dilution caused by quantum processes in the synchrotron radiation energy loss mechanism, the bending radii are large (279 m) and very high gradient (n = 32824) AG cells are arranged in trains of low dispersion, terrain following achromats. First experiences in operating a system of over 900 magnets, each with beam position monitors and corrector magnet movers, spanning 9000 feet, are described.
Date: February 1, 1987
Creator: Fischer, G.E.; Brown, K.L.; Bulos, F.; Fieguth, T.; Hutton, A.; Murray, J.J. et al.
Partner: UNT Libraries Government Documents Department

Progress with the AGS Booster

Description: Rare K-decay, neutrino and heavy ion physics demands that a rapid- cycling high vacuum and high intensity Booster be built for the AGS at Brookhaven. For each mode of operation there are corresponding accelerator physics and design issues needing special attention. Problems pertinent to any single mode of operation have been encountered and solved before, but putting high intensity proton requirements and high vacuum heavy ion requirements into one machine demands careful design considerations and decisions. The lattice design and magnet characteristics will be briefly reviewed. Major design issues will be discussed and design choices explained. Finally, the construction status and schedule will be presented. 6 refs., 6 figs.
Date: January 1, 1988
Creator: Weng, W.T.
Partner: UNT Libraries Government Documents Department

Simulation of proton RF capture in the AGS Booster

Description: RF capture of the proton beam in the AGS Booster has been simulated with the longitudinal phase-space tracking code ESME. Results show that a capture in excess of 95% can be achieved with multiturn injection of a chopped beam.
Date: January 1, 1988
Creator: Khiari, F.Z.; Luccio, A.U. & Weng, W.T.
Partner: UNT Libraries Government Documents Department

Fundamentals: Longitudinal motion

Description: This paper discusses the following topics on synchrotrons: Dynamics of Synchrotron; Acceleration Cavity; Beam Manipulation and Beam Control; and High Intensity Effects. 21 refs., 26 figs. (LSP)
Date: November 7, 1988
Creator: Weng, W.T.
Partner: UNT Libraries Government Documents Department