IBIC2013 - List of Keywords (focusing)

Paper	Title	Other Keywords	Page
MOPF08	Design and Performance of the Upgraded LHC Synchrotron Light Monitor	LHC, undulator, optics, dipole	220
	A. Goldblatt, E. Bravin, F. Roncarolo, G. Trad CERN, Geneva, Switzerland
	The LHC is equipped with two synchrotron radiation systems, one per beam, used to measure the transverse bunch distributions. The light emitted by a superconducting undulator and/or by a dipole magnet (depending on beam energy) is intercepted by an extraction mirror in vacuum and sent through a viewport to the imaging Beam Synchrotron Radiation Telescope (BSRT). The first version of the telescope, used from 2009 to mid 2012, was based on spherical focusing mirrors in order to minimize chromatic aberrations. However, this required a very complicated delay line in order to switch the focus between the two different light sources as a function of beam energy. A new system based on optical lenses was designed and installed in mid 2012 in order to simplify the optical line and thus reduce misalignment and focusing errors. The first results with LHC beam using this new system showed a significant reduction in the correction factor required to match the emittance as measured by wire scanners. This contribution discusses the performance of the new optical system, presenting the LHC results and comparing simulations with measurement performed in the laboratory using a BSRT replica.

MOPF09	A Gas-Jet Profile Monitor for the CLIC Drive Beam	electron, ion, CLIC, space-charge	224
	A. Jeff, E.B. Holzer, T. Lefèvre CERN, Geneva, Switzerland A. Jeff, V. Tzoganis, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom V. Tzoganis, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	The Compact LInear Collider (CLIC) will use a novel acceleration scheme in which energy extracted from a very intense beam of relatively low-energy electrons (the Drive Beam) is used to accelerate a lower intensity Main Beam to very high energy. The high intensity of the Drive Beam, with pulses of more than 10¹⁵ electrons, poses a challenge for conventional profile measurements such as wire scanners. Thus, new non-invasive profile measurements are being investigated. Profile monitors using gas ionisation or fluorescence have been used at a number of accelerators. Typically, extra gas must be injected at the monitor and the rise in pressure spreads some distance down the beampipe. In contrast, a gas jet can be fired across the beam into a receiving chamber, with little gas escaping into the rest of the beam pipe. In addition, a gas jet shaped into a thin plane can be used like a screen on which the beam cross-section is imaged. In this paper we present some arrangements for the generation of such a jet. In addition to jet shaping using nozzles and skimmers, we propose a new scheme to use matter-wave interference with a Fresnel Zone Plate to bring an atomic jet to a narrow focus.

MOPF28	Optics Non-Linear Components Measurement Using BPM Signals	optics, BPM, beam-losses, synchrotron	279
	M. Alhumaidi, A.M. Zoubir TU Darmstadt, Darmstadt, Germany
	The knowledge of linear and non-linear errors in circular accelerator optics is very crucial for controlling and compensating resonances and their consequent beam losses. This is indispensable, especially for high intensity machines. Fortunately, the relationship between the recorded beam offset signals at the BPMs is a manifestation of the accelerator optics, and can therefore be exploited in the determination of the optics linear and non-linear components. We propose a novel method for estimating lattice non-linear components located in-between the positions of two BPMs by analyzing the beam offset signals of a BPMs triple containing these two BPMs. Depending on the non-linear components in-between the locations of the BPMs triple, the relationship between the beam offsets follows a multivariate polynomial. After calculating the covariance matrix of the polynomial terms, the Generalized Total Least Squares method is used to find the model parameters, and thus the non-linear components. Finally, a bootstrap technique is used to determine confidence intervals of the estimated values. Results for synthetic data are shown.

TUPF14	Description of Laser Transport and Delivery System for the FETS Laserwire Emittance Scanner	laser, coupling, diagnostics, emittance	527
	A. Bosco, G.E. Boorman, S. Emery, S.M. Gibson Royal Holloway, University of London, Surrey, United Kingdom C. Gabor STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom T. Hofmann CERN, Geneva, Switzerland A.P. Letchford STFC/RAL, Chilton, Didcot, Oxon, United Kingdom J.K. Pozimski, P. Savage Imperial College of Science and Technology, Department of Physics, London, United Kingdom
	A beam emittance monitor for H⁻ beams based on laser-induced ions neutralization is being developed at the Front End Test Stand (FETS) at the Rutherford Appleton Laboratory (RAL). The laser system that will be used for the photo-neutralization of the H⁻ beam is a fiber laser emitting 110 ns pulses at λ=1064nm, with a repetition rate of 30 kHz and peak power of 8 kW. The laser will be conveyed to the interaction area over a distance of 70 m via an optical fiber. An assembly of two remotely controlled motorized translation stages will enable the system to scan across the H⁻ beam along its vertical profile. A motorized beam expander will control the output size of the collimated laser beam in order to enable the system to operate with different spatial characteristics of the ions beam. In this paper we present a full account of the laser characteristics, the optical transport system and the final delivery assembly. All the relevant measurements such as power, spatial and temporal characteristics of the laser, fiber transport efficiency and final delivery laser beam parameters will be reported.
	Poster TUPF14 [4.081 MB]

Paper

Title

Other Keywords

Page

MOPF08

Design and Performance of the Upgraded LHC Synchrotron Light Monitor

LHC, undulator, optics, dipole

220

A. Goldblatt, E. Bravin, F. Roncarolo, G. Trad
CERN, Geneva, Switzerland

The LHC is equipped with two synchrotron radiation systems, one per beam, used to measure the transverse bunch distributions. The light emitted by a superconducting undulator and/or by a dipole magnet (depending on beam energy) is intercepted by an extraction mirror in vacuum and sent through a viewport to the imaging Beam Synchrotron Radiation Telescope (BSRT). The first version of the telescope, used from 2009 to mid 2012, was based on spherical focusing mirrors in order to minimize chromatic aberrations. However, this required a very complicated delay line in order to switch the focus between the two different light sources as a function of beam energy. A new system based on optical lenses was designed and installed in mid 2012 in order to simplify the optical line and thus reduce misalignment and focusing errors. The first results with LHC beam using this new system showed a significant reduction in the correction factor required to match the emittance as measured by wire scanners. This contribution discusses the performance of the new optical system, presenting the LHC results and comparing simulations with measurement performed in the laboratory using a BSRT replica.

MOPF09

A Gas-Jet Profile Monitor for the CLIC Drive Beam

electron, ion, CLIC, space-charge

224

A. Jeff, E.B. Holzer, T. Lefèvre
CERN, Geneva, Switzerland
A. Jeff, V. Tzoganis, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
V. Tzoganis, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

The Compact LInear Collider (CLIC) will use a novel acceleration scheme in which energy extracted from a very intense beam of relatively low-energy electrons (the Drive Beam) is used to accelerate a lower intensity Main Beam to very high energy. The high intensity of the Drive Beam, with pulses of more than 10¹⁵ electrons, poses a challenge for conventional profile measurements such as wire scanners. Thus, new non-invasive profile measurements are being investigated. Profile monitors using gas ionisation or fluorescence have been used at a number of accelerators. Typically, extra gas must be injected at the monitor and the rise in pressure spreads some distance down the beampipe. In contrast, a gas jet can be fired across the beam into a receiving chamber, with little gas escaping into the rest of the beam pipe. In addition, a gas jet shaped into a thin plane can be used like a screen on which the beam cross-section is imaged. In this paper we present some arrangements for the generation of such a jet. In addition to jet shaping using nozzles and skimmers, we propose a new scheme to use matter-wave interference with a Fresnel Zone Plate to bring an atomic jet to a narrow focus.

MOPF28

Optics Non-Linear Components Measurement Using BPM Signals

optics, BPM, beam-losses, synchrotron

279

M. Alhumaidi, A.M. Zoubir
TU Darmstadt, Darmstadt, Germany

The knowledge of linear and non-linear errors in circular accelerator optics is very crucial for controlling and compensating resonances and their consequent beam losses. This is indispensable, especially for high intensity machines. Fortunately, the relationship between the recorded beam offset signals at the BPMs is a manifestation of the accelerator optics, and can therefore be exploited in the determination of the optics linear and non-linear components. We propose a novel method for estimating lattice non-linear components located in-between the positions of two BPMs by analyzing the beam offset signals of a BPMs triple containing these two BPMs. Depending on the non-linear components in-between the locations of the BPMs triple, the relationship between the beam offsets follows a multivariate polynomial. After calculating the covariance matrix of the polynomial terms, the Generalized Total Least Squares method is used to find the model parameters, and thus the non-linear components. Finally, a bootstrap technique is used to determine confidence intervals of the estimated values. Results for synthetic data are shown.

TUPF14

Description of Laser Transport and Delivery System for the FETS Laserwire Emittance Scanner

laser, coupling, diagnostics, emittance

527

A. Bosco, G.E. Boorman, S. Emery, S.M. Gibson
Royal Holloway, University of London, Surrey, United Kingdom
C. Gabor
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
T. Hofmann
CERN, Geneva, Switzerland
A.P. Letchford
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
J.K. Pozimski, P. Savage
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

A beam emittance monitor for H⁻ beams based on laser-induced ions neutralization is being developed at the Front End Test Stand (FETS) at the Rutherford Appleton Laboratory (RAL). The laser system that will be used for the photo-neutralization of the H⁻ beam is a fiber laser emitting 110 ns pulses at λ=1064nm, with a repetition rate of 30 kHz and peak power of 8 kW. The laser will be conveyed to the interaction area over a distance of 70 m via an optical fiber. An assembly of two remotely controlled motorized translation stages will enable the system to scan across the H⁻ beam along its vertical profile. A motorized beam expander will control the output size of the collimated laser beam in order to enable the system to operate with different spatial characteristics of the ions beam. In this paper we present a full account of the laser characteristics, the optical transport system and the final delivery assembly. All the relevant measurements such as power, spatial and temporal characteristics of the laser, fiber transport efficiency and final delivery laser beam parameters will be reported.

Poster TUPF14 [4.081 MB]