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Optimizing receiver configurations for resolution of equivalent dipole polarizabilities in situ

Description: Equivalent dipole polarizabilities are a succinct way to summarize the inductive response of an isolated conductive body at distances greater than the scale of the body. At any time lag or frequency, an equivalent dipole polarizability response is comprised of 9 parameters; six specifying an equivalent dipole polarizability matrix (which is symmetric) and three specifying the apparent location of the body center. Smith and Morrison (2002) give equations for calculating uncertainties in equivalent dipole polarizability and position based on analysis of an iterative linearized inversion. Here, the root mean squared uncertainty in polarizability is weighted and summed over a number of control points and minimized using an evolutionary algorithm for a number of instrument designs. Three families of designs are presented: single transmitter systems for use on a 2-D grid of positions with negligible error in relative instrument location, two transmitter systems for use on a line of positions with negligible error in relative instrument location, and three transmitter systems for stand alone use. Results for the one and two transmitter systems are strongly degraded by errors in instrument position, whereas the three transmitter systems are insensitive to instrument positioning errors.
Date: February 12, 2004
Creator: Smith, J. Torquil & Morrison, H. Frank
Partner: UNT Libraries Government Documents Department

Test Results on Nb3Sn Dipole Magnets

Description: A cosine theta type dipole magnet using Nb{sub 3}Sn conductor have been designed, built and tested. D19H is a two-layer dipole magnet with a Nb{sub 3}Sn inner layer and a NbTi outer layer. Coil-pairs are connected with two of the four Nb{sub 3}Sn splices in a high field region, and compressed by a ring and collet system. It trained well at 4.4K, but poorly at 1.8K. Strain gages revealed that the coil-ends were not loaded well enough for high field operation (after cool-down), so another thermal cycle is planned. The low end-load is believed to be the cause of several mysteries observed during operation. Except for the outer-layer 1.8 K training difficulty, the magnet's operation was encouraging.
Date: December 12, 1996
Creator: Lietzke, A.F.; Benjegerdes, R.; Caspi, S.; Dell'Orco, D.; Harnden, W.; McInturff, A.D. et al.
Partner: UNT Libraries Government Documents Department

TERMINATION OF IDEAL COS m phi WINDING

Description: Configurations are proposed, and illustrated, for terminating the 'cosine {phi}' windings of an ideal iron-free dipole magnet so as to preserve the quality of the internal field integrated (vs. z) through the entire magnet. The end windings are placed on a surface of the same radius as that on which the conductors lie in the central (2-D) portion of the structure. The desired pure dipole quality of the integrated field then is assured by requiring that the z-component of current, after projection onto the y-z plane, shall have in that plane a density distribution whose integral is independent of y. As a result of the analysis, end-winding configurations that satisfy this requirement are proposed in which each conductor filament follows through the transition region a locus whose y-z projection is of the form z(y;Y{sub 0}) = f(y{sub 0}) - f(y-y{sub 0}), with f(0) = 0, wherein Y{sub 0} serves as an index to identify the location of the filament in the central (2-D) portion of the structure. Simple solutions of this nature are indicated in which the function f has the form f(y-y{sub 0}) = k (y-y{sub 0}{sup p}/a) for windings on the surface of a cylinder of radius {und a}, with p < 1 (and preferably p {le} 1/2) to ensure a smooth transition into the end region. The straightforward extension of these results to configurations for the production of integrated fields of higher multipolarity also is indicated.
Date: April 1, 1986
Creator: Laslett, L.J.; Caspi, S. & Helm, M.
Partner: UNT Libraries Government Documents Department

Fabrication and Test Results of a Nb3Sn Superconducting Racetrack Dipole Magnet

Description: A 'proof-of-principle' Nb{sub 3}Sn superconducting dual-bore dipole magnet was built from racetrack coils, as a first step in a program to develop an economical, 15 Tesla, accelerator-quality magnet. The mechanical design and magnet fabrication procedures are discussed. No training was required to achieve temperature-dependent plateau currents, despite several thermal cycles that involved partial magnet disassembly and substantial pre-load variations. Subsequent magnets are expected to approach 15 Tesla with substantially improved conductor.
Date: February 6, 2000
Creator: Chow, K.; Dietderich, D.R.; Gourlay, S.A.; Gupta, R.; Harnden, W.; Lietzke, A. F. et al.
Partner: UNT Libraries Government Documents Department

Fabrication and Test Results of a Nb3Sn Superconducting Racetrack Dipole Magnet

Description: A 'proof-of-principle' Nb{sub 3}Sn superconducting dual-bore dipole magnet was built from racetrack coils, as a first step in a program to develop an economical, 15 Tesla, accelerator-quality magnet. The mechanical design and magnet fabrication procedures are discussed. No training was required to achieve temperature-dependent plateau currents, despite several thermal cycles that involved partial magnet disassembly and substantial pre-load variations. Subsequent magnets are expected to approach 15 Tesla with substantially improved conductor.
Date: March 22, 1999
Creator: Chow, K.; Dietderich, D.R.; Gourlay, S.A.; Gupta, R.; Harnden, W.; Lietzke, A.F. et al.
Partner: UNT Libraries Government Documents Department

Multi-transmitter multi-receiver null coupled systems forinductive detection and characterization of metallic objects

Description: Equivalent dipole polarizabilities are a succinct way tosummarize the inductive response of an isolated conductive body atdistances greater than the scale of the body. Their estimation requiresmeasurement of secondary magnetic fields due to currents induced in thebody by time varying magnetic fields in at least three linearlyindependent (e.g., orthogonal) directions. Secondary fields due to anobject are typically orders of magnitude smaller than the primaryinducing fields near the primary field sources (transmitters). Receivercoils may be oriented orthogonal to primary fields from one or twotransmitters, nulling their response to those fields, but simultaneouslynulling to fields of additional transmitters is problematic. Iftransmitter coils are constructed symmetrically with respect to inversionin a point, their magnetic fields are symmetric with respect to thatpoint. If receiver coils are operated in pairs symmetric with respect toinversion in the same point, then their differenced output is insensitiveto the primary fields of any symmetrically constructed transmitters,allowing nulling to three (or more) transmitters. With a sufficientnumber of receivers pairs, object equivalent dipole polarizabilities canbe estimated in situ from measurements at a single instrument sitting,eliminating effects of inaccurate instrument location on polarizabilityestimates. The method is illustrated with data from a multi-transmittermulti-receiver system with primary field nulling through differencedreceiver pairs, interpreted in terms of principal equivalent dipolepolarizabilities as a function of time.
Date: October 17, 2005
Creator: Smith, J. Torquil; Morrison, H. Frank; Doolittle, Lawrence R. & Tseng, Hung-Wen
Partner: UNT Libraries Government Documents Department

GLOBAL AND LOCAL COUPLING COMPENSATION EXPERIMENTS IN RHIC USING AC DIPOLES.

Description: Compensation of transverse coupling during the RHIC energy ramp has been proven to be non-trivial and tedious. The lack of accurate knowledge of the coupling sources has initiated several efforts to develop fast techniques using turn-by-turn BPM data to identify and compensate these sources. This paper aims to summarize the beam experiments performed to measure the coupling, matrix and resonance driving terms with the aid of RHIC ac dipoles at injection energy.
Date: June 26, 2006
Creator: CALAGA, R. & FRANCHI, A. (GSI), TOMAS, R.(CERN)
Partner: UNT Libraries Government Documents Department

A MODEL FOR DETERMINING DIPOLE, QUADRUPOLE, AND COMBINED FUNCTION MAGNET COSTS.

Description: One of the most important considerations in designing large accelerators is cost. This paper describes a model for estimating accelerator magnet costs, including their dependences on length, radius, and field. The reasoning behind the cost model is explained, and the parameters of the model are chosen so as to correctly give the costs of a few selected magnets. A comparison is made with earlier formulae. Estimates are also given for other costs linearly dependent on length, and for 200 MHz superconducting RF.
Date: September 14, 2004
Creator: PALMER, R. B. & BERG,S. J.
Partner: UNT Libraries Government Documents Department

Universality of Unintegrated Gluon Distributions at small x

Description: We systematically study dijet production in various processes in the small-x limit and establish an effective kt-factorization for hard processes in a system with dilute probes scattering on a dense target. In the large-Nc limit, the unintegrated gluon distributions involved in different processes are shown to be related to two widely proposed ones: the Weizsacker-Williams gluon distribution and the dipole gluon distribution.
Date: January 4, 2011
Creator: Dominguez, Fabio; Marquet, Cyrille; Xiao, Bowen & Yuan, Feng
Partner: UNT Libraries Government Documents Department

Resolution depths for some transmitter receiverconfigurations

Description: Away from a conductive body, secondary magnetic fields due to currents induced in the body by a time varying external magnetic field are approximated by (equivalent) magnetic dipole fields. Approximating the external magnetic field by its value at the location of the equivalent magnetic dipoles, the equivalent magnetic dipoles' strengths are linearly proportional to the external magnetic field, for a given time dependence of external magnetic field, and are given by the equivalent dipole polarizability matrix. The polarizability matrix and its associated equivalent dipole location is estimated from magnetic field measurements made with at least three linearly independent polarizations of external magnetic fields at the body. Uncertainties in the polarizability matrix elements and its equivalent dipole location are obtained from analysis of a linearized inversion for polarizability and dipole location. Polarizability matrix uncertainties are independent of the scale of the polarizability matrix. Dipole location uncertainties scale inversely with the scale of the polarizability matrix. Uncertainties in principal polarizabilities and directions are obtained from the sensitivities of eigenvectors and eigenvalues to perturbations of a symmetric matrix. In application to synthetic data from a magnetic conducting sphere and to synthetic data from an axially symmetric elliptic conducting body, the estimated polarizability matrices, equivalent dipole locations and principal polarizabilities and directions are consistent with their estimated uncertainties.
Date: August 28, 2002
Creator: Smith, J. Torquil; Morrison, H. Frank & Becker, Alex
Partner: UNT Libraries Government Documents Department

Field errors introduced by eddy currents in Fermilab main injector magnets

Description: The Fermilab Main Injector ramps from 8 GeV to 120 GeV in about half a second. The rapidly changing magnetic field induces eddy currents in the stainless steel vacuum tubes, which in turn produce error fields that can affect the beam. Field calculations and measurements are presented for the dipole and quadrupole magnets.
Date: October 1, 1997
Creator: Walbridge, D.G.C.; Brown, B.C.; Dinanco, J.B.; Sharoran, S.A. & Sim, J.W.
Partner: UNT Libraries Government Documents Department

Booster synchrotron frequency below transition

Description: The dipole mode synchrotron frequency is a basic beam parameter; it and a few similarly basic quantities measured at small time intervals serve to characterize the longitudinal beam dynamics throughout the acceleration cycle. The effective accelerating voltage, in conjunction with the amount of rf voltage required for the acceleration, is important for the estimate of the beam energy loss per turn. The dipole mode frequency can be used to obtain the effective accelerating rf voltage, providing that it can be measured precisely. The synchrotron frequency measured from the synchrotron phase detector signal (SPD) generally agrees well with calculation, and it can be applied for such purposes as inferring the effective rf voltage.
Date: April 21, 2004
Creator: al., Xi Yang et
Partner: UNT Libraries Government Documents Department

A protype dipole septum magnet for fast high current kicker systems

Description: A dipole "septum" magnet without a material septum has been designed and tested as part of a fast beam kicker system for use in intense, electron-beam induction accelerators. This septum magnet is a simple, iron-based electromagnet with two static, oppositely oriented dipole field regions used to provide further separation of beam centroids given a small angle kick by a fast beam kicker. The magnet geometry includes removable pole pieces to allow experimental flexibility. Field errors experienced by the beam depend crucially on the magnitude of the initial kick that provides displacement of the beam centroids from the transition region between the two dipole field regions. Results of simulations are reported.
Date: March 29, 1999
Creator: Wang, L F; Caporaso, G J; Chen, Y J; Lund, S M; Poole, B R & Brown, T F
Partner: UNT Libraries Government Documents Department

FIRST POLARIZED PROTON COLLISIONS AT RHIC.

Description: We successfully injected polarized protons in both RHIC rings and maintained polarization during acceleration up to 100 GeV per ring using two Siberian snakes in each ring. Each snake consists of four helical superconducting dipoles which rotate the polarization by 180{sup o} about a horizontal axis. This is the first time that polarized protons have been accelerated to 100 GeV.
Date: November 6, 2002
Creator: ROSER,T.; AHRENS,L.; ALESSI,J.; BAI,M.; BEEBE-WANG,J.; BRENNAN,J.M. et al.
Partner: UNT Libraries Government Documents Department

Development of a single-layer Nb3Sn common coil dipole model

Description: A high-field dipole magnet based on the common coil design was developed at Fermilab for a future Very Large Hadron Collider. A short model of this magnet with a design field of 11 T in two 40-mm apertures is being fabricated using the react-and-wind technique. In order to study and optimize the magnet design two 165-mm long mechanical models were assembled and tested. A technological model consisting of magnet straight section and ends was also fabricated in order to check the tooling and the winding and assembly procedures. This paper describes the design and technology of the common coil dipole magnet and summarizes the status of short model fabrication.The results of the mechanical model tests and comparison with FE mechanical analysis are also presented.
Date: December 13, 2002
Creator: al., Igor Novitski et
Partner: UNT Libraries Government Documents Department

Expressions for the threshold current of multipass beam breakup in recirculating linacs from single cavity models

Description: We investigate multipass beam breakup (BBU) in a recirculating linear accelerator in the framework of a single cavity model. We present expressions for the beam breakup threshold current for various situations derived from a perturbative solution of BBU equations. These formulae should serve as a guide to understand the BBU phenomenon for a particular system and also as a tool to estimate the BBU threshold current quickly. Many of the results presented are more general than previous considerations because they include the effects of coupling between the two transverse polarizations in each dipole higher order mode.
Date: October 1, 2005
Creator: Yunn, Byung C.
Partner: UNT Libraries Government Documents Department

Oscillating Vertical Magnetic Dipole Above a Conducting Half-Space

Description: The electromagnetic field produced by a vertical oscillating magnetic dipole above a plane conducting earth is obtained in integral form. An exact solution in closed form is obtained for the case in which the dipole and the point of observation are both located on the surface of the earth. (auth)
Date: April 1, 1961
Creator: Wesley, J. P.
Partner: UNT Libraries Government Documents Department

Differential Relationships Between Momentum Magnetic Field, Orbit Length, and Revolution Frequency

Description: The purpose of this memo is to put down, in one place, a number of commonly used accelerator formulae. I'll also comment briefly on the derivation of these relationships. Nothing in this memo is my original work. All of this was developed many years ago by the brilliant founders of the field of Accelerator Physics. The widely used differential relationships between beam momentum (p), dipole magnetic field (B), orbit length (L), and revolution frequency (f) are given in Table 1.
Date: February 9, 2001
Creator: Werkema, Steve
Partner: UNT Libraries Government Documents Department

Quadrupole Focussing and Quadrupole Steering Tolerances for the 8 GeV AP3-P1 Lattice

Description: This note will outline the sensitivity to emittance blowup of antiproton transfers due to quadrupole focussing and quadrupole steering errors in the 8 GeV AP3-P1 transfer line. It will be shown that these tolerances are much larger than the dipole steering tolerances discussed in PBAR Note 649. This note will use the lattice discussed in PBAR Note 648.
Date: February 5, 2001
Creator: McGinnis, Dave
Partner: UNT Libraries Government Documents Department

Excitation of a TEM Cell by a Vertical Electric Hertzian Dipole

Description: From abstract: The excitation of a transverse electromagnetic (TEM) cell by a vertical electric Hertzian dipole is analyzed where the gap between the septum and side wall is assumed to be small. Approximate expressions for the field distribution and characteristic impedance are derived. These expressions are numerically evaluated for some typical geometries, and good agreement with previously published results is shown. The formation also allows a vertical offset for the septum position, thus offering more flexibility of increasing the size of the test area to accommodate larger pieces of test equipment.
Date: March 1981
Creator: Wilson, Perry F.; Chang, David C. & Ma, Mark T.
Partner: UNT Libraries Government Documents Department