ICAP2018 - List of Keywords (quadrupole)

Paper	Title	Other Keywords	Page
SUPAF10	Reconstruction of Particle Distributions at RFQ Exit at SNS Beam Test Facility	rfq, simulation, emittance, lattice	76
	Z.L. Zhang ORNL RAD, Oak Ridge, Tennessee, USA A.V. Aleksandrov, S.M. Cousineau ORNL, Oak Ridge, Tennessee, USA
	Fluctuations of beam parameters and uncertainties of quadrupole gradients during measurements have effects on the reconstruction of initial particle distributions. To evaluate these effects, the concept of a distribution discrepancy is proposed. Results suggest effects of fluctuations of beam parameters are small, while uncertainties of quadrupole gradients are the main factors that affect the reconstructed distributions. By comparing the measured distributions with distributions produced by tracking the reconstructed initial distributions, it is proved that the real or quasi-real (closest to real) initial distribution can be obtained as long as the minimum distribution discrepancy is found.
	Slides SUPAF10 [8.261 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAF10
About •	paper received ※ 18 October 2018 paper accepted ※ 27 January 2019 issue date ※ 26 January 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

SUPAG03	Challenges in Extracting Pseudo-Multipoles From Magnetic Measurements	multipole, induction, dipole, experiment	87
	S. Russenschuck, G. Caiafa, L. Fiscarelli, M. Liebsch, C. Petrone, P. Rogacki CERN, Geneva, Switzerland
	Extracting the coefficients of Fourier-Bessel series, known as pseudo-multipoles or generalized gradients, from magnetic measurements of accelerator magnets involves technical and mathematical challenges. First, a novel design of a short, rotating-coil magnetometer is required that does not intercept any axial field component of the magnet. Moreover, displacing short magnetometers, step-by-step along the magnet axis, yields a convolution of the local multipole field errors and the sensitivity (test function) of the induction coil. The deconvolution must then content with the low signal-to-noise ratio of the measurands, which are integrated voltages corresponding to spatial flux distributions. Finally, the compensation schemes, as implemented on long coils used for measuring the integrated field harmonics, cannot be applied to short magnetometers. All this requires careful design of experiment to derive the optimal length of the induction coil, the step size of the scan, and the highest order of pseudo-multipoles in the field reconstruction. This paper presents the theory of the measurement method, the data acquisition and deconvolution, and the design and production of a saddle-shaped, rotating-coil magnetometer.
	Slides SUPAG03 [4.548 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAG03
About •	paper received ※ 18 October 2018 paper accepted ※ 27 January 2019 issue date ※ 26 January 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF15	A Holistic Approach to Simulating Beam Losses in the Large Hadron Collider Using BDSIM	collimation, simulation, beam-losses, ECR	221
	S.D. Walker, A. Abramov, S.T. Boogert, H. Garcia Morales, S.M. Gibson, L.J. Nevay, H. Pikhartova, W. Shields JAI, Egham, Surrey, United Kingdom
	To fully understand the beam losses, subsequent radiation, energy deposition, backgrounds and activation in particle accelerators, a holistic approach combining a 3-D model, physics processes and accelerator tracking is required. Beam Delivery Simulation (BDSIM) is a program developed to simulate the passage of particles, both primary and secondary, in particle accelerators and calculate the energy deposited by these particles via material interactions using the Geant4 physics library. A Geant4 accelerator model is built from an existing optical description of a lattice by procedurally placing a set of predefined accelerator components. These generic components can be refined to an arbitrary degree of detail with the use of user-defined geometries, detectors, field maps, and more. A detailed model of the Large Hadron Collider has been created in BDSIM, validated with existing tracking codes and applied to study beam loss patterns.
	Slides TUPAF15 [2.065 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAF15
About •	paper received ※ 31 October 2018 paper accepted ※ 08 December 2018 issue date ※ 26 January 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAG22	Main and Fringe Field Computations for the Electrostatic Quadrupoles of the Muon g-2 Experiment Storage Ring	multipole, experiment, storage-ring, FEL	313
	E.V. Valetov, M. Berz MSU, East Lansing, Michigan, USA
	Funding: This work was supported by the U.S. Department of Energy under Contract DE-FG02-08ER41546 and by Fermi Research Alliance for U.S. Department of Energy under Contract DE-AC02-07CH11359. We consider semi-infinite electrostatic deflectors with plates of different thickness, including plates with rounded edges, and we calculate their electrostatic potential and field using conformal mappings. To validate the calculations, we compare the fringe fields of these electrostatic deflectors with fringe fields of finite electrostatic capacitors, and we extend the study to fringe fields of adjacent electrostatic deflectors with consideration of electrostatic induction, where field falloffs of semi-infinite electrostatic deflectors are slower than exponential and thus behave differently from most magnetic fringe fields. Building on the success with electrostatic deflectors, we develop a highly accurate and fully Maxwellian conformal mappings method for calculation of main fields of electrostatic particle optical elements. A remarkable advantage of this method is the possibility of rapid recalculations with geometric asymmetries and mispowered plates. We use this conformal mappings method to calculate the multipole terms of the high voltage quadrupole used in the storage ring of the Muon g-2 Experiment (FNAL-E-0989). Completing the methodological framework, we present a method for extracting multipole strength falloffs of a particle optical element from a set of Fourier mode falloffs. We calculate the quadrupole strength falloff and its effective field boundary (EFB) for the Muon g-2 quadrupole, which has explained the experimentally measured tunes, while simple estimates based on a linear model exhibited discrepancies up to 2%.
	Slides TUPAG22 [3.780 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAG22
About •	paper received ※ 15 October 2018 paper accepted ※ 28 January 2019 issue date ※ 26 January 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

SUPAF10

Reconstruction of Particle Distributions at RFQ Exit at SNS Beam Test Facility

rfq, simulation, emittance, lattice

76

Z.L. Zhang
ORNL RAD, Oak Ridge, Tennessee, USA
A.V. Aleksandrov, S.M. Cousineau
ORNL, Oak Ridge, Tennessee, USA

Fluctuations of beam parameters and uncertainties of quadrupole gradients during measurements have effects on the reconstruction of initial particle distributions. To evaluate these effects, the concept of a distribution discrepancy is proposed. Results suggest effects of fluctuations of beam parameters are small, while uncertainties of quadrupole gradients are the main factors that affect the reconstructed distributions. By comparing the measured distributions with distributions produced by tracking the reconstructed initial distributions, it is proved that the real or quasi-real (closest to real) initial distribution can be obtained as long as the minimum distribution discrepancy is found.

Slides SUPAF10 [8.261 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAF10

About •

paper received ※ 18 October 2018 paper accepted ※ 27 January 2019 issue date ※ 26 January 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

SUPAG03

Challenges in Extracting Pseudo-Multipoles From Magnetic Measurements

multipole, induction, dipole, experiment

87

S. Russenschuck, G. Caiafa, L. Fiscarelli, M. Liebsch, C. Petrone, P. Rogacki
CERN, Geneva, Switzerland

Extracting the coefficients of Fourier-Bessel series, known as pseudo-multipoles or generalized gradients, from magnetic measurements of accelerator magnets involves technical and mathematical challenges. First, a novel design of a short, rotating-coil magnetometer is required that does not intercept any axial field component of the magnet. Moreover, displacing short magnetometers, step-by-step along the magnet axis, yields a convolution of the local multipole field errors and the sensitivity (test function) of the induction coil. The deconvolution must then content with the low signal-to-noise ratio of the measurands, which are integrated voltages corresponding to spatial flux distributions. Finally, the compensation schemes, as implemented on long coils used for measuring the integrated field harmonics, cannot be applied to short magnetometers. All this requires careful design of experiment to derive the optimal length of the induction coil, the step size of the scan, and the highest order of pseudo-multipoles in the field reconstruction. This paper presents the theory of the measurement method, the data acquisition and deconvolution, and the design and production of a saddle-shaped, rotating-coil magnetometer.

Slides SUPAG03 [4.548 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAG03

About •

paper received ※ 18 October 2018 paper accepted ※ 27 January 2019 issue date ※ 26 January 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF15

A Holistic Approach to Simulating Beam Losses in the Large Hadron Collider Using BDSIM

collimation, simulation, beam-losses, ECR

221

S.D. Walker, A. Abramov, S.T. Boogert, H. Garcia Morales, S.M. Gibson, L.J. Nevay, H. Pikhartova, W. Shields
JAI, Egham, Surrey, United Kingdom

To fully understand the beam losses, subsequent radiation, energy deposition, backgrounds and activation in particle accelerators, a holistic approach combining a 3-D model, physics processes and accelerator tracking is required. Beam Delivery Simulation (BDSIM) is a program developed to simulate the passage of particles, both primary and secondary, in particle accelerators and calculate the energy deposited by these particles via material interactions using the Geant4 physics library. A Geant4 accelerator model is built from an existing optical description of a lattice by procedurally placing a set of predefined accelerator components. These generic components can be refined to an arbitrary degree of detail with the use of user-defined geometries, detectors, field maps, and more. A detailed model of the Large Hadron Collider has been created in BDSIM, validated with existing tracking codes and applied to study beam loss patterns.

Slides TUPAF15 [2.065 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAF15

About •

paper received ※ 31 October 2018 paper accepted ※ 08 December 2018 issue date ※ 26 January 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAG22

Main and Fringe Field Computations for the Electrostatic Quadrupoles of the Muon g-2 Experiment Storage Ring

multipole, experiment, storage-ring, FEL

313

E.V. Valetov, M. Berz
MSU, East Lansing, Michigan, USA

Funding: This work was supported by the U.S. Department of Energy under Contract DE-FG02-08ER41546 and by Fermi Research Alliance for U.S. Department of Energy under Contract DE-AC02-07CH11359.
We consider semi-infinite electrostatic deflectors with plates of different thickness, including plates with rounded edges, and we calculate their electrostatic potential and field using conformal mappings. To validate the calculations, we compare the fringe fields of these electrostatic deflectors with fringe fields of finite electrostatic capacitors, and we extend the study to fringe fields of adjacent electrostatic deflectors with consideration of electrostatic induction, where field falloffs of semi-infinite electrostatic deflectors are slower than exponential and thus behave differently from most magnetic fringe fields. Building on the success with electrostatic deflectors, we develop a highly accurate and fully Maxwellian conformal mappings method for calculation of main fields of electrostatic particle optical elements. A remarkable advantage of this method is the possibility of rapid recalculations with geometric asymmetries and mispowered plates. We use this conformal mappings method to calculate the multipole terms of the high voltage quadrupole used in the storage ring of the Muon g-2 Experiment (FNAL-E-0989). Completing the methodological framework, we present a method for extracting multipole strength falloffs of a particle optical element from a set of Fourier mode falloffs. We calculate the quadrupole strength falloff and its effective field boundary (EFB) for the Muon g-2 quadrupole, which has explained the experimentally measured tunes, while simple estimates based on a linear model exhibited discrepancies up to 2%.

Slides TUPAG22 [3.780 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAG22

About •

paper received ※ 15 October 2018 paper accepted ※ 28 January 2019 issue date ※ 26 January 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)