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An imaginary-{gamma}{sub t} lattice with dispersion-free straights for the 50 GeV high-intensity proton synchrotron

Description: During polarized beam experiments, the 50 GeV proton synchrotron, proposed by the Institute of Nuclear Study of Japan, requires zero-dispersion straight sections. This will be implemented by turning on a special excitation of the quadrupoles resulting in a dispersion wave through the arcs of the machine. Aside from the inconvenience of the power supply, this special excitation also brings about unwanted high betatron functions and high dispersion functions, which will eventually limit the performance of the accelerator at high intensities. In this paper, dispersion suppressors are introduced. A new preliminary lattice that contains two straight sections with nonzero dispersion and two straight sections with zero dispersion is presented. The whole ring remains having a reasonable imaginary {gamma}{sub t}. The horizontal and vertical betatron functions have been kept to below 32.4 m and dispersion function between -0.52 and 1.86 m. The number of 6.2 m dipoles is reduced from 96 to 92, and the dipole field at 50 GeV will become slightly above 18 T. Some analysis of the new lattice is discussed. 10 refs., 9 figs., 1 tab.
Date: February 1, 1997
Creator: Ng, K.-Y.
Partner: UNT Libraries Government Documents Department

Emittance growth of an electron beam in a periodic focusing channel due to transfer of longitudinal energy to transverse energy

Description: Most discussions about emittance growth and halo production for an intense electron beam in a periodic focusing channel assume that the total transverse energy is constant (or, in other words, that the transverse and longitudinal Hamiltonians are separable). Previous analyses that include variations in the total transverse energy are typically based on a transverse-longitudinal coupling that is either from two-dimensional space-charge modes or particle-particle Coulomb collisions. With the space-charge modes, the energy exchange between the transverse and longitudinal directions is periodic, and of constant magnitude. The total energy transfer for the case of the Coulomb collisions is negligible. This limited increase of energy in the transverse direction from these other effects will limit the amount of transverse emittance growth possible. In this paper, the authors investigate a mechanism in which there is a continual transfer of energy from the longitudinal direction to the transverse direction, leading to essentially unlimited potential transverse emittance growth. This mechanism is caused by an asymmetry of the beam`s betatron motion within the periodic focusing elements. This analysis is based on thermodynamic principles. This mechanism exists for both solenoids and quadrupole focusing, although only solenoid focusing is studied here.
Date: December 31, 1998
Creator: Carlsten, B. E.
Partner: UNT Libraries Government Documents Department

Theorem on magnet fringe field

Description: Transverse particle motion in particle accelerators is governed almost totally by non-solenoidal magnets for which the body magnetic field can be expressed as a series expansion of the normal (b{sub n}) and skew (a{sub n}) multipoles, B{sub y} + iB{sub x} = {summation}(b{sub n} + ia{sub n})(x + iy){sup n}, where x, y, and z denote horizontal, vertical, and longitudinal (along the magnet) coordinates. Since the magnet length L is necessarily finite, deflections are actually proportional to ``field integrals`` such as {bar B}L {equivalent_to} {integral} B(x,y,z)dz where the integration range starts well before the magnet and ends well after it. For {bar a}{sub n}, {bar b}{sub n}, {bar B}{sub x}, and {bar B}{sub y} defined this way, the same expansion Eq. 1 is valid and the ``standard`` approximation is to neglect any deflections not described by this expansion, in spite of the fact that Maxwell`s equations demand the presence of longitudinal field components at the magnet ends. The purpose of this note is to provide a semi-quantitative estimate of the importance of {vert_bar}{Delta}p{sub {proportional_to}}{vert_bar}, the transverse deflection produced by the ion-gitudinal component of the fringe field at one magnet end relative to {vert_bar}{Delta}p{sub 0}{vert_bar}, the total deflection produced by passage through the whole magnet. To emphasize the generality and simplicity of the result it is given in the form of a theorem. The essence of the proof is an evaluation of the contribution of the longitudinal field B{sub x} from the vicinity of one magnet end since, along a path parallel to the magnet axis such as path BC.
Date: December 31, 1995
Creator: Wei, Jie & Talman, R.
Partner: UNT Libraries Government Documents Department

Particle beams with uniform transverse distribution

Description: A successfully tested method is described which achieves a more uniform illumination of an extended flat target by the charged particle beam from an accelerator, by proper use of a combination of quadrupole and octupole magneto-optical elements.
Date: October 1, 1996
Creator: Tsoupas, N.; Zucker, M.S.; Snead, C.L. & Ward, T.E.
Partner: UNT Libraries Government Documents Department

Tune control in the Fermilab Main Injector

Description: We describe methods used to measure and control tunes in the Fermilab Main Injector (FMI). Emphasis is given to software implementation of the operator interface, to the front-end embedded computer system, and handling of hysteresis of main dipole and quadrupole magnets. Techniques are developed to permit control of tune of the Main Injector through several acceleration cycles: from 8.9 GeV/c to 120 GeV/c, from 8.9 GeV/c to 150 GeV/c, and from 150 GeV/c to 8.9 GeV/c. Systems which automate the complex interactions between tune measurement and the variety of ramping options are described. Some results of tune measurements and their comparison with the design model are presented.
Date: April 16, 1999
Creator: Wu, G.; Brown, B. C.; Capista, D. P.; Flora, R. H.; Johnson, D. E. & Martin, K. S.
Partner: UNT Libraries Government Documents Department

Unexpected matching insensitivity in DTL of GTA accelerator

Description: The Intertank Matching Section (IMS) of the Ground Test Accelerator (GTA) contains four variable-field quadrupoles (VFQs) and is designed to match beam exiting the Radio-Frequency Quadrupole to the first tank of the Drift-tube LINAC (DTL-1). By varying the VFQ field strengths to create a range of beam mismatches at the entrance to DTL-1, one can test the sensitivity of the DTL-1 output beam to variations in the DTL-1 input beam. Experimental studies made during commissioning of the GTA indicate an unexpected result: the beam exiting DTL-1 shows little variation for a range of mismatches produced at the entrance. Results of the experiment and simulation studies are presented.
Date: May 1995
Creator: Yuan, V. W.; Gilpatrick, J. D.; Johnson, K. F.; Lysenko, W. P.; Rusthoi, D. P.; Sander, O. R. et al.
Partner: UNT Libraries Government Documents Department

Hysteresis study techniques and results for accelerator magnets with unipolar current excitation

Description: Using an automated magnet measurement system employing a variety of current excitation ramps, extensive studies of the hysteretic behavior of magnet strength have been carried out. An analytic description which is accurate at better than 0.1% has been achieved. Prescriptions for setting field strength using these formulas will be adequate for multi-energy operation of the Fermilab Main Injector, for deceleration in the Main Injector and Accumulator and for multi-energy operation of various beamline magnets. An overview of this work is provided. Important regularities of the magnet behavior are identified.
Date: April 23, 1999
Creator: Brown, Bruce C.
Partner: UNT Libraries Government Documents Department

Beam-based magnetic alignment of the final focus test beam

Description: In order to optimize tunability and backgrounds in linear collider final focus systems, it is necessary to align strong quadrupole and sextupole magnets with beam-based measurements. Algorithms for alignment have been used successfully on the Final Focus Test Beam (FFTB) beamline at SLAC. Quadrupole magnets were aligned using a shunt technique, with resolutions from 50 microns down to 700 nanometers. Sextupole magnets were aligned by moving the magnets transverse to the beam and observing the kick on downstream beam position monitors. This procedure resulted in sextupole misalignment resolutions of 5 to 20 microns. All magnets were then moved into aligned positions via remote-controlled stages capable of sub-micron resolution. Details of the fitting algorithms, results of the measurement, and potential improvements in the system are discussed.
Date: May 1, 1995
Creator: Tenenbaum, P.; Burke, D.; Helm, R.; Irwin, J.; Raimondi, P.; Oide, K. et al.
Partner: UNT Libraries Government Documents Department

Setting reference targets

Description: Reference Targets are used to represent virtual quantities like the magnetic axis of a magnet or the definition of a coordinate system. To explain the function of reference targets in the sequence of the alignment process, this paper will first briefly discuss the geometry of the trajectory design space and of the surveying space, then continue with an overview of a typical alignment process. This is followed by a discussion on magnet fiducialization. While the magnetic measurement methods to determine the magnetic centerline are only listed (they will be discussed in detail in a subsequent talk), emphasis is given to the optical/mechanical methods and to the task of transferring the centerline position to reference targets.
Date: April 1, 1997
Creator: Ruland, R.E.
Partner: UNT Libraries Government Documents Department

Superconducting sextupoles and trim quadrupoles for RHIC

Description: RHIC requires 288 sextupole and 72 trim quadrupole magnets. These iron poletip superconducting magnets have been constructed by Everson Electric Co. Room temperature field measurements have been completed for 75% of these magnets with acceptable results. Approximately 15% of them have been tested at 4.6 K for maximum (quench) current. The quench performance for the early magnets was good and improved to excellent during the production run. These magnets have more than 100% margin at quench.
Date: May 1, 1995
Creator: Thompson, P.; Anerella, M. & Ganetis, G.
Partner: UNT Libraries Government Documents Department

A low emittance lattice for the NSLS X-Ray Ring

Description: A new high-brightness lattice for the NSLS X-Ray Ring is presented. The horizontal emittance of the X-Ray Ring can be reduced by a factor of two to three by allowing nonzero dispersion in the insertion device straight sections and by better controlling the periodicity of the dispersion. Beam was stored in a low emittance lattice during machine studies. The dispersion in the operations lattice lacks the 8-fold periodicity of the magnet structure, because the orbit is offset in the sextupoles. During machine studies the focusing effect of the sextupoles was compensated using trim supplies on the quadrupoles in the dispersive straight sections. Measured results will be presented. A discussion of the hardware upgrade requirements that would be necessary to run the low emittance lattice in operations is also included.
Date: June 1, 1995
Creator: Safranek, J.
Partner: UNT Libraries Government Documents Department

Conceptual designs for IR optics at C-Zero

Description: Two possible conceptual optical designs for a stand-alone C0 IR insert were presented. Both inserts are optically transparent to the rest of the machine, with no impact on Run IIb Tevatron operating parameters. Both design variations require high-field LHC-like quadrupoles for the final focus triplet. In the first version, with enhanced dipoles creating space for separators in the arcs, collisions can be created at all 3 IP's simultaneously. Stronger dipoles also free more than 26 m of space for the detector. At C0, {beta}* is limited to {ge}50 cm by {beta}max in the IR triplets. The second version of the IR has neither new dipoles nor new arc separators. Collider scenarios have either B0 and D0 at collision, or just C0. At C0, {beta}* can be decreased to 40 cm, but the price paid is a substantial reduction in free space available for the detector. This first pass at C0 IR designs has left a number of questions unresolved. A few of these outstanding issues that a second iteration of the IR designs must address are discussed.
Date: August 28, 2000
Creator: Johnstone, John A.
Partner: UNT Libraries Government Documents Department

Design, construction, and procurement methodology of magnets for the 7-GeV Advanced Photon Source

Description: All major magnets of the Advanced Photon Source (APS) have now been measured and installed in the facility. This paper describes the mechanical design, construction, and procurement philosophy and methodology, and lessons learned from the construction and procurement of more than 1500 magnets for the APS storage ring, injector synchrotron ring, and positron accumulator ring.
Date: June 1995
Creator: Gorski, A.; Argyrakis, J. & Biggs, J.
Partner: UNT Libraries Government Documents Department

Combined element magnet production for the relativistic heavy ion collider (RHIC) at BNL

Description: The production of 432 combined element magnets for RHIC is well underway. These magnets consist of a superconducting corrector, a quadrupole, and a sextupole combined into an integrated cold mass which is inserted into a cryostat. Production experiences as well as test results are reported.
Date: May 1, 1995
Creator: Mulhall, S.; Foelsche, H. & Ganetis, G.
Partner: UNT Libraries Government Documents Department

The beam envelope equation-systematic solution for a periodic quadrupole lattice with space charge

Description: Many approximate solutions for matched beam envelope functions with space charge have been developed; they generally have errors of 2-10% for the parameters of interest and cannot be reliably improved. The new, systematic approach described here provides the K-V envelope functions to high accuracy as a power series in the quadrupole gradient. A useful simplification results from defining the sum and difference of the envelope radii; S = (a+b)/2 varies only slightly with distance z along the system axis, and D = (a-b)/2 contains most of the envelope oscillations. To solve the coupled equations for S and D, the quadrupole strength K(z) is turned on by replacing K with {alpha}K{sub 1} and letting {alpha} increase continuously from 0 to 1. It is found that S and D may be expanded in even and odd powers of {alpha}, respectively. Equations for the coefficients of powers of {alpha} are then solved successively by integration in z. The periodicity conditions and tune integration close the calculation. Simple low order results are typically accurate to 1% or better.
Date: April 1, 1995
Creator: Lee, E.P.
Partner: UNT Libraries Government Documents Department

Particle beam generator using a radioactive source

Description: The apparatus of the present invention selects from particles emitted by a radioactive source those particles having momentum within a desired range and focuses the selected particles in a beam having at least one narrow cross-dimension, and at the same time attenuates potentially disruptive gamma rays and low energy particles. Two major components of the present invention are an achromatic bending and focusing system, which includes sector magnets and quadrupole, and a quadrupole doublet final focus system. Permanent magnets utilized in the apparatus are constructed of a ceramic (ferrite) material which is inexpensive and easily machined.
Date: December 31, 1991
Creator: Underwood, D.G.
Partner: UNT Libraries Government Documents Department

Superconducting 8 CM Corrector magnets for the relativistic heavy ion collider (RHIC)

Description: RHIC will require 420 80 mm Corrector magnets. The magnets are made up of coils wound on a computer controlled wiring machine using ultrasonic power to bond the wire into an epoxy coated flat substrate. The coils are wrapped onto support tubes and concentrically assembled inside an iron yoke. These magnets are being built at Brookhaven National Laboratory (BNL) with more than 280 constructed by May 1, 1995. Design, construction and test results are presented.
Date: May 1, 1995
Creator: Morgillo, A.; Escallier, J. & Ganetis, G.
Partner: UNT Libraries Government Documents Department

Magnetic design of trim excitations for the advanced light source storage ring sextupole

Description: The Advanced Light Source (ALS) storage ring sextupole is a unique multi-purpose magnet. It is designed to operate as a sextupole with three auxiliary trim modes: horizontal steering, vertical steering, and skew quadrupole. A perturbation theory for iron-dominated magnets developed by Klaus Halbach provides the basis for this design. The three trim excitations are produced by violating sextupole symmetry and are thus perturbations of the normal sextupole excitation. The magnet was designed such that all four modes are decoupled and can be excited independently. This paper discusses the use of Halbach`s perturbation theory to design the trim functions and to evaluate the primary asymmetry in the sextupole mode, namely, a gap in the return yoke to accommodate the vacuum chamber.
Date: June 1, 1995
Creator: Marks, S.
Partner: UNT Libraries Government Documents Department

A final focus system for the Next Linear Collider

Description: The final focus of the Next Linear Collider (NLC) demagnifies electron and positron beams of 250--750 GeV energy down to a transverse size of about 2.5 {times} 350 nm{sup 2} at the interaction point (IP). The basic layout, momentum bandwidth, vibration tolerances, wakefield effects, and the tunability of the proposed final focus design are discussed. Also a perspective is given on the crab cavity and on effects of the solenoid field in the interaction region.
Date: June 1, 1995
Creator: Zimmermann, F.; Brown, K.; Emma, P.; Helm, R.; Irwin, J.; Tenenbaum, P. et al.
Partner: UNT Libraries Government Documents Department

Overview of the Final Focus Test Beam alignment system

Description: The Final Focus Test Beam was conceived as a technological stepping stone on the way to the next linear collider. Nowhere is this more evident than with the alignment subsystems. Alignment tolerances for components prior to beam turn are almost an order of magnitude smaller than for previous projects at SLAC. Position monitoring systems which operate independent of the beam are employed to monitor motions of the components locally and globally with unprecedented precision. An overview of the FFTB alignment system is presented herein.
Date: May 1, 1993
Creator: Bressler, V. E.; Ruland, R. E. & Plouffe, D.
Partner: UNT Libraries Government Documents Department

Transfer matrices of superimposed magnets and RF cavity

Description: Superimposed magnets often occur in accelerators, such as in the interaction regions of colliders. This note presents the linear transfer matrices of various superimposed magnets. Since readers of this note are probably well informed, the authors simply list the results without derivation. The method used to calculate the linear transfer matrices is outlined elsewhere. The authors list the Hamiltonian H and the corresponding matrix e{sup :-sH:} for several combinations of common magnets (only sector magnets without fringe field) used in accelerators. Magnetic fields and vector potentials (in Coulomb gauge) are also listed for reference. The usual (x, y, s) coordinate system is used. The transfer matrices are for the commonly used canonical variables (x, P{sub x}, y, P{sub y}, z, {delta}). For those cases when the transfer matrices depend on the gauge selection, the authors also list the matrices for the coordinates and kinetic momenta (x, p{sub x}, y, p{sub y}). The magnetic fields and Hamiltonians are correct only up to the order appropriate for linear optics. In this computer age, complicated analytical results may lose their usefulness and attractiveness in many applications. However, the authors hope their exact analytic results to linear order are still useful for particle dynamics studies in superimposed magnet systems.
Date: November 1, 1996
Creator: Wang, Shun-xi & Chao, A.
Partner: UNT Libraries Government Documents Department