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The Brown-Servranckx matching transformer for simultaneous RFQ to DTL H{sup +} and H{sup {minus}} matching

Description: The issue involved in simultaneous matching of H{sup +} and H{sup -} beams between an RFQ and DTL lies in the fact that both beams experience the same electric-field forces at a given position in the RFQ. Hence, the two beams are focused to the same correlation. However, matching to a DTL requires correlation of the opposite sign. The Brown-Servranckx quarter-wave ({lambda}/4) matching transformer system, which requires four quadrupoles, provides a method to simultaneously match H{sup +} and H{sup -} beams between an RFQ and a DTL. The method requires the use of a special RFQ section to obtain the Twiss parameter conditions {beta}{sup x}={beta}{sup y} and {alpha}{sub x}={alpha}{sub y}=0 at the exit of the RFQ. This matching between the RFQ and DTL is described.
Date: September 1, 1996
Creator: Wadlinger, E.A. & Garnett, R.W.
Partner: UNT Libraries Government Documents Department

Low energy ring lattice of the PEP-II asymmetric B-Factory

Description: Developing a lattice that contains a very low beta value at the interaction point (IP) and has adequate dynamic aperture is one of the major challenges in designing the PEP-II asymmetric B-factory. For the Low Energy Ring (LER) the authors have studied several different chromatic correction schemes since the conceptual design report (CDR). Based on these studies, a hybrid solution with local and semi-local chromatic sextupoles has been selected as the new baseline lattice to replace the local scheme in the CDR. The new design simplifies the interaction region (IR) and reduces the number of sextupoles in the arcs. Arc sextupoles are paired at {pi} phase difference and are not interleaved. In this paper the authors describe the baseline lattice with the emphasis on the lattice changes made since the CDR.
Date: June 1, 1995
Creator: Cai, Y.; Donald, M.; Helm, R.; Irwin, J.; Nosochkov, Y.; Ritson, D.M. et al.
Partner: UNT Libraries Government Documents Department

Perturbation of the periodic dispersion under beam crossing optics in LHC

Description: Beam crossing and separation schemes in the LHC interaction regions impose non-zero closed orbit in the low-{beta} triplets. The related perturbative dispersion is derived ; propagation, multi-crossing interference, perturbative effects around the ring are investigated and quantified. Horizontal and vertical compensation schemes are presented.
Date: May 1, 1997
Creator: Meot, F.
Partner: UNT Libraries Government Documents Department

Correction of vertical crossing induced dispersion in LHC

Description: Beam crossing schemes in the LHC interaction regions impose non-zero vertical closed orbit in the low-{beta} triplets, which excite a perturbative periodic dispersion ; the phenomenon is described and quantified in detail. It is shown that this dispersion reaches values at the limit of tolerances in the nominal optics of Version 5.0 of the LHC ring, and prohibitively large values in particular in the low- {beta} quadrupoles and interaction regions in the foreseen extreme {beta}-squeeze case ({beta}{sup *} = 0.25 m). Such behaviour justifies including a local correction in the LHC design, in order to damp the effect and confine it as much as possible in the vicinity of the excitation sources (the low-{beta} triplets). An optical compensation scheme based on the use of skew quadrupoles is described in detail, as well as the entailed residual dispersion.
Date: November 1, 1997
Creator: Meot, F.
Partner: UNT Libraries Government Documents Department

How to construct a second-order achromat with a 90 degree phase advance

Description: The author shows how to construct a second order achromatic (T{sub ij6} = 0, i, j {element_of} {l_brace}1,2{r_brace}) beamline with a total phase advance of 450{degree} (360{degree} + 90{degree}). The goal is to construct a 90{degree} cell which is achromatic to second order. One possible way to do this is to construct a 360{degree} sector followed by a 90{degree} cell; put dipoles and sextupoles in the 360{degree} sector; and throw the aberrations into the 90{degree} cell such that the final transformation is achromatic. The author expresses the aberrations in the 360{degree} sector in terms of the 90{degree} cell and determine whether any combination of sextupoles gives the correct cancellation.
Date: July 5, 2000
Creator: Kobilarcik, T.
Partner: UNT Libraries Government Documents Department

Functional dependence, broad-band fitting, and ancillary conditions

Description: The ability to make multiple passes through a charged particle optical system, as a single step in a mathematical procedure, opens up new computational capa- bilities. At the simplest level, the functional dependence of any transfer matrix of any order, or any beam phase-space parameter can be plotted as a function of any other parameter used to describe the optical con#12;guration. Secondly, broad-band #12;tting can be done on aberrations, where all orders are considered simultaneously according to their importance on the #12;nal phase-space beam distribution. Finally, ancillary conditions may be imposed in the calculation of functional dependences. For example, the dependence of a matrix element on a beam line parameter may be calculated and plotted, subject to constraints imposed on other matrix elements. The computer program TRANSPORT now has these capabilities. Additional examples will be given.
Date: November 1, 1998
Creator: Carey, David C.
Partner: UNT Libraries Government Documents Department


Description: For the year 2001 run, a bent crystal was installed in the yellow ring of the Relativistic Heavy Ion Collider (RHIC). The crystal forms the first stage of a two stage collimation system. By aligning the crystal to the beam, halo particles are channeled through the crystal and deflected into a copper scraper. The purpose is to reduce beam halo with greater efficiency than with a scraper alone. In this paper we present the first results from the use of the crystal collimator. We compare the crystal performance under various conditions, such as different particle species, and beta functions.
Date: June 2, 2002
Partner: UNT Libraries Government Documents Department

The linear parameters and the decoupling matrix for linearly coupled motion in 6 dimensional phase space. Informal report

Description: It will be shown that starting from a coordinate system where the 6 phase space coordinates are linearly coupled, one can go to a new coordinate system, where the motion is uncoupled, by means of a linear transformation. The original coupled coordinates and the new uncoupled coordinates are related by a 6 {times} 6 matrix, R. R will be called the decoupling matrix. It will be shown that of the 36 elements of the 6 {times} 6 decoupling matrix R, only 12 elements are independent. This may be contrasted with the results for motion in 4-dimensional phase space, where R has 4 independent elements. A set of equations is given from which the 12 elements of R can be computed from the one period transfer matrix. This set of equations also allows the linear parameters, {beta}{sub i}, {alpha}{sub i} = 1, 3, for the uncoupled coordinates, to be computed from the one period transfer matrix. An alternative procedure for computing the linear parameters, the {beta}{sub i}, {alpha}{sub i} i = 1, 3, and the 12 independent elements of the decoupling matrix R is also given which depends on computing the eigenvectors of the one period transfer matrix. These results can be used in a tracking program, where the one period transfer matrix can be computed by multiplying the transfer matrices of all the elements in a period, to compute the linear parameters {alpha}{sub i} and {beta}{sub i}, i = 1, 3, and the elements of the decoupling matrix R. The procedure presented here for studying coupled motion in 6-dimensional phase space can also be applied to coupled motion in 4-dimensional phase space, where it may be a useful alternative procedure to the procedure presented by Edwards and Teng. In particular, it gives a simpler programming procedure for computing the beta ...
Date: March 1, 1995
Creator: Parzen, G.
Partner: UNT Libraries Government Documents Department

Linear optics correction in the CEBAF accelerator

Description: During commissioning of the CEBAF accelerator, correcting dispersion, momentum compaction and betatron beam envelopes was essential for robust operation. To speed the diagnostic process we developed a method which allows one to track and correct the machine optics on-line. The method is based on measuring the propagation of 30 Hz modulated betatron oscillations. The beam optics of the accelerator was altered to decrease lattice sensitivity at critical points and to simplify control of the betatron function match. The calculation of the Courant-Snyder invariant from signals of each pair of beam position monitors was used for a correction of the betatron functions. The experience of optics correction and the study of long and short term machine reproducibility obtained during 1996 and early 1997 are also discussed. With minor modifications this method can also be used for on-line optics measurement and correction in circular accelerators.
Date: June 1, 1997
Creator: Lebedev, V.A.; Bickley, M. & Bisognano, J.
Partner: UNT Libraries Government Documents Department

DIMAD Based Interactive Simulation of the CEBAF Accelerator

Description: An X-Windows^(TM) based interactive interface to the DIMAD beam optics program enables users to simulate the adjustment of magnets in tuning various segments of the CEBAF beamline.In addition, users can track the effects of random errors on the path of individual particles as magnets are adjusted.The interface sits on top of the standard DIMAD model, retaining the detailed modeling available with that code.Because X-Windows software was used, the code is portable to any system that has X-Windows and the X-Windows Toolkit available.We give results from the studies simulating the extraction portion of the CEBAF beamline.
Date: May 1, 1991
Creator: Douglas, David & Bickley, Matthew
Partner: UNT Libraries Government Documents Department

Correction of closed orbit distortions in the horizontal direction

Description: Many computer programs with a variety of algorithms exist for controlling the closed orbit in synchrotrons. The scope of this note is rather modest in comparison. Based on a simple model, a study has been made to find out statistically how much kick angle is needed by each steering element and how much residual closed orbit deviation should be expected when the closed orbit is steered to go through the center of seven position monitors (M{sub 2} through M{sub 8}) in each cell. Seven independent kicks are supplied by two trim dipoles B{sub U} and B{sub D}, and six steering elements (H{sub 1} through H{sub 6}) with H{sub 3} and H{sub 4} assumed to have the same kick angle. If it is necessary to remove H{sub 3} to make a space there for a correction skew quadrupole (in every other cell), the kick angle of H{sub 4} would have to be doubled.
Date: February 1, 1988
Creator: Ohnuma, S.
Partner: UNT Libraries Government Documents Department

Automated tuning of the advanced photon source booster synchrotron

Description: The acceleration cycle of the Advanced Photon Source (APS) booster synchrotron is completed within 223 ms and is repeated at 2 Hz. Unless properly corrected, transverse and longitudinal injection errors can lead to inefficient booster performance. In order to simplify daily operation, automated tuning methods have been developed. Through the use of beam position monitor (BPM) reading, transfer line corrector magnets, magnet ramp timing, and empirically determined response functions, the injection process is optimized by correcting the first turn trajectory to the measured closed orbit. These tuning algorithms and their implementation are described here along with an evaluation of their performance.
Date: August 1, 1997
Creator: Biedron, S.G. & Milton, S.V.
Partner: UNT Libraries Government Documents Department

Progress in silicon-to-silicon direct bonding and its application to synchrotron x-ray optics

Description: X-ray optical elements (such as single-crystal silicon monochromators) illuminated with high-power synchrotron-radiation beams produced by insertion devices and, to a lesser extent bending magnets, require cooling, When operating a silicon crystal at room temperature, channels for the coolant are often fabricated directly beneath the diffracting surface. Then a separate silicon distribution manifold/plenum is manufactured, and the components are bonded together using an adhesive or some intermediate material. In many cases, such monochromators suffer from strains induced by the bond. A silicon-to-silicon direct-bonding technique (i.e., without any intermediate material) has been developed that appears to be an attractive method for creating a bond with less strain between two pieces of silicon. This technique is well understood for the case of thin wafers ({approximately}0.5 mm thickness) and is used by the semiconductor industry. Recently, bonding of 16-mm-thick 10-cm-diameter silicon crystals has been successfully performed inducing very little strain. A short review of the silicon-to-silicon crystals has been successfully performed inducing very little strain. A short review of the silicon-to-silicon direct-bonding process will be presented with an emphasis on its application to room temperature high-heat-load x-ray optics with the present status of direct bonding efforts at the APS.
Date: February 1, 1997
Creator: Graber, T.; Krasnicki, S. & Fernandez, P.B.
Partner: UNT Libraries Government Documents Department

Mirror mounts designed for the Advanced Photon Source SRI-CAT

Description: Use of a mirror for beamlines at third-generation synchrotron radiation facilities, such as the Advanced Photon Source (APS) at Argonne National laboratory, has many advantages. A mirror as a first optical component provides significant reduction in the beam peak heat flux and total power on the downstream monochromator and simplifies the bremsstrahlung shielding design for the beamline transport. It also allows one to have a system for multibeamline branching and switching. More generally, a mirror is used for beam focusing and/or low-pass filtering. Six different mirror mounts have been designed for the SRI-CAT beamlines. Four of them are designed as water-cooled mirrors for white or pink beam use, and the other two are for monochromatic beam use. Mirror mount designs, including vacuum vessel structure and precision supporting stages, are presented in this paper.
Date: September 1, 1997
Creator: Shu, D.; Benson, C. & Chang, J.
Partner: UNT Libraries Government Documents Department

Beam chopper For the Low-Energy Undulator Test Line (LEUTL) in the APS

Description: The low-energy undulator test line (LEUTL) is being built and will be tested with a short beam pulse from an rf gun in the Advanced Photon Source (APS) at the Argonne National Laboratory. In the LEUTL a beam chopper is used after the rf gun to deflect the unwanted beam to a beam dump. The beam chopper consists of a permanent magnet and an electric deflector that can compensate for the magnetic deflection. A 30-kV pulsed power supply is used for the electric deflector. The chopper subsystem was assembled and tested for beamline installation. The electrical and beam properties of the chopper assembly are presented.
Date: August 1, 1997
Creator: Kang, Y.; Wang, J.; Milton, S. & Teng, L.
Partner: UNT Libraries Government Documents Department

General design of the layout for the Advanced Photon Source beamline front ends

Description: In the first phase of construction, sixteen insertion device beamline front ends and sixteen bending magnet beamline front ends will be built by 1995 for the Advanced Photon Source (APS). Designs for these front ends have been completed. In this paper, the particular designs and specifications as well as the optical and bremsstrahlung ray-tracing analysis for the APS front ends are presented.
Date: October 5, 1993
Creator: Shu, D. & Kuzay, T.M.
Partner: UNT Libraries Government Documents Department

Beam dynamics design of the 211 MeV APT normal conducting linac

Description: This paper describes the normal conducting linac design that is part of the Accelerator for Production of Tritium (APT) project. The new version of PARMILA designed this linac. This linac accepts the beam from the 6.7 MeV radio frequency quadrupole without a separate matching section. At about 10 MeV, it has a smooth transition in the length of period from 8{beta}{lambda} to 9{beta}{lambda} in quadrupole focusing lattice. This adjustment of the period was needed to provide sufficient space for the quadrupole focusing magnets and beam diagnostic equipment. The linac consists of the coupled cavity drift tube linac up to 97 MeV and coupled cavity linac above 97 MeV.
Date: December 31, 1998
Creator: Young, L.M.; Billen, J.H.; Takeda, H. & Wood, R.L.
Partner: UNT Libraries Government Documents Department

Gyrotron-based millimeter-wave beams for material processing

Description: Los Alamos scientists, working with the National Center for Manufacturing Sciences have assembled a materials processing facility utilizing gyrotron based RF sources. The facility is intended to demonstrate unique features available at 30 to 84 GHz. This paper presents an overview of their quasi-optical facility and describes the microwave hardware.
Date: October 1, 1997
Creator: Hardek, T.W.; Cooke, W.D.; Perry, W.L. & Rees, D.E.
Partner: UNT Libraries Government Documents Department

Magnetic design and measurement of nonlinear multipole magnets for the APT beam expander system

Description: Two prototype nonlinear multipole magnets have been designed for use in the 800-MeV beam test of the APT beam-expansion concept at LANSCE. The iron-dominated magnets each consist of three independent coils, two for producing a predominantly octupole field with a tunable duodecapole component, and one for canceling the residual quadrupole field. Two such magnets, one for shaping each transverse plane, are required to produce a rectangular, uniform beam current density distribution with sharp edges on the APT target. This report will describe the magnetic design of these magnets, along with field measurements, and a comparison to the magnetic design.
Date: October 1, 1997
Creator: Barlow, D.B.; Shafer, R.E.; Martinez, R.P.; Walstrom, P.L.; Kahn, S.; Jain, A. et al.
Partner: UNT Libraries Government Documents Department

Continuous contour phase plates for tailoring the focal plane irradiance profile

Description: We present fully continuous phase screens for producing super-Gaussian focal-plane irradiance profiles. Such phase screens are constructed with the assumption of either circular symmetric near-field and far-field profiles or a separable phase screen in Cartesian co-ordinates. In each case, the phase screen is only a few waves deep. Under illumination by coherent light, such phase screens produce high order super-Gaussian profiles in the focal plane with high energy content effects of beam aberrations on the focal profiles and their energy content are also discussed.
Date: August 9, 1995
Creator: Dixit, S.N.; Rushford, M.C.; Thomas, I.M. & Perry, M.D.
Partner: UNT Libraries Government Documents Department