IPAC2012 - List of Keywords (octupole)

Paper	Title	Other Keywords	Page
MOPPD049	The Layout of the High Energy Beam Transport for the European Spallation Source	target, linac, quadrupole, beam-transport	475
	A.I.S. Holm, S.P. Møller, H.D. Thomsen ISA, Aarhus, Denmark
	The status of the High Energy Beam Transport (HEBT) line for the European Spallation Source (ESS) is presented. The HEBT brings the beam from the underground linac to the target at surface level. The main design objectives of the HEBT, such as space for upgrades, producing the desired target footprint etc. are discussed and the preferred design is shown. Large amplitude particles, a halo, are formed in the last part of the linac. Hence, every given value of the peak current density at the target is correlated with a certain power deposited outside the beam footprint. This correlation is studied and optimized. Furthermore, first studies of the vertical stability of the beam footprint and profile on target due to misalignment or mismatch of the incoming beam are made.

MOPPP079	Magnetic Tuning of the APS Wiggler as a Study for Tuning the NSLS-II Damping Wiggler	wiggler, multipole, damping, insertion	747
	I. Vasserman, M. Abliz, E. Gluskin, E. Trakhtenberg, J.Z. Xu ANL, Argonne, USA
	Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357 A wide variety of tuning techniques has been developed and employed at Advanced Photon Source (APS) in the course of tuning insertion devices for use on the APS storage ring, the APS free electron laser, and in assisting with the LCLS undulator tuning. The tuning requirements for the National Synchrotron Source II (NSLS-II) damping wigglers are very demanding and include limits on the off-midplane field integrals that are new in the repertoire of undulator magnetic tuning. The goal of this study was to assess the applicability of existing tuning techniques to meeting the off-midplane requirements of NSLS-II. Tests were run using an available APS 8.5-cm-period wiggler. In addition to existing techniques, a special new shim design was tested. This report summarizes the results of these tests and shows that the wiggler can be tuned to the required specifications on the midplane over the requested ±15 mm in the horizontal direction. In the vertical direction, however, the specifications could only be met within ±0.5 mm. This falls short of the ±15 mm by ± 3 mm good-field region that is sought by NSLS-II.

TUOAA02	Focusing Charged Particle Beams Using Multipole Magnets in a Beam Transport Line	sextupole, multipole, target, focusing	1062
	Y. Yuri, I. Ishibori, T. Ishizaka, S. Okumura, T. Yuyama JAEA/TARRI, Gunma-ken, Japan
	The intensity distribution of a charged-particle beam is transformed by applying the nonlinear focusing force of a multipole magnet. In this paper, the transformation of the transverse intensity distribution due to the second-order sextupole and third-order octupole focusing force in the beam transport line is explored. As a measure of the distribution transformation induced by the multipole magnets, the beam centroid displacement and the change of the beam size have been analytically derived using the distribution function of the beam. It is numerically verified how the transverse distribution of the beam is transformed by the multipole magnets. As an application of the distribution transformation by nonlinear focusing, a uniform beam can be formed from a Gaussian beam using multipole magnets. The current status and future plan of the experiment on the uniform-beam formation at the cyclotron facility in Japan Atomic Energy Agency will be shown.
	Slides TUOAA02 [2.032 MB]

TUPPC005	Optimization of the SIS100 Nonlinear Magnet Scheme for Slow Extraction	extraction, sextupole, lattice, dynamic-aperture	1158
	A. Saa Hernandez, M.M. Kirk, D. Ondreka, N. Pyka, S. Sorge, P.J. Spiller GSI, Darmstadt, Germany
	The SIS100 superconducting synchrotron was initially planned mainly for fast extraction of protons and heavy ions. Due to the delay of the construction of the SIS300 synchrotron, SIS100 has to be able to provide slowly extracted heavy ion beams to the experiments. To improve the robustness of the slow extraction from SIS100, a lattice review was performed, resulting in an optimization of the nonlinear magnet scheme. In the original scheme the Hardt condition cannot be established due to a collapse of the dynamic aperture caused by the chromatic sextupoles. In the optimized scheme the positions of the chromatic sextupoles are modified and octupoles are employed to compensate the second order effects of these sextupoles. In addition, the number of resonance sextupole magnets is reduced. With the new scheme, the Hardt condition can be established, leading to higher extraction efficiency. The separatrix can be freely adjusted, and closed orbit control is improved.

TUPPC077	Numerical Study of Beam Trapping in Stable Islands for Simple 2D Models of Betatronic Motion	emittance, simulation, resonance, extraction	1350
	M. Giovannozzi, C. Hernalsteens CERN, Geneva, Switzerland
	An essential ingredient for the proposed Multi-Turn Extraction (MTE) at the CERN PS is the beam trapping in stable islands. The control of the trapping process is essential for the quality of the final beam in terms of intensity sharing and emittance. In this paper, the splitting process is studied quantitatively by means of numerical simulations performed on 2D model representing the horizontal non-linear betatronic motion. The results are reviewed and discussed in details.

TUPPC099	Optimization of Chromaticity Compensation and Dynamic Aperture in MEIC Collider Rings	sextupole, ion, dynamic-aperture, collider	1389
	F. Lin, Y.S. Derbenev, V.S. Morozov, Y. Zhang JLAB, Newport News, Virginia, USA K.B. Beard Muons, Inc, Batavia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Supported in part by US DOE STTR grant DE-SC0006272. The conceptual design of the Medium-energy Electron-Ion Collider (MEIC) at Jefferson Lab relies on an ultra-small beta-star to achieve high luminosities of up to 10³⁴ cm^-2s⁻¹. A low-beta insertion for interaction regions unavoidably induces large chromatic effects that demand a proper compensation. The present approach of chromatic compensation in the MEIC collider rings is based on a local correction scheme using two symmetric chromatic compensation blocks that includes families of sextupoles, and are placed in a beam extension area on both sides of a collision point. It can simultaneously compensate the first order chromaticity and chromatic beam smear at the IP without inducing significant second order aberrations. In this paper, we investigate both the momentum acceptance and dynamic aperture in the MEIC ion collider ring by considering the aberration effects up to the third order, such as amplitude dependent tune shift. We also explore the compensation of the third order effects by introducing families of octupoles in the extended beam area. Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Supported in part by US DOE STTR grant DE-SC0006272.

TUPPR017	Nonlinear Post-Linac Energy Collimation System for the Compact Linear Collider	sextupole, collimation, luminosity, simulation	1846
	J. Resta-López, A. Faus-Golfe IFIC, Valencia, Spain
	Funding: FPA2010-21456-C02-01 The post-linac energy collimation system of the Compact Linear Collider (CLIC) has been designed to provide protection of the Beam Delivery System (BDS) against off-energy and mis-steered beams. The conventional baseline design consists of a two stage spoiler-absorber scheme. The CLIC energy collimators are required to withstand the impact of a full bunch train. This condition makes the energy collimator design very challenging, since the collimators have to deal with a total beam power of 14 MW at nominal energy and intensity. The increase of the transverse spot size at the collimators using nonlinear magnets could be a potential solution to guarantee the survivability of the collimators. In this paper we present an alternative nonlinear optics design for the CLIC energy collimation system. Possibilities for its optimization are discussed in view of performance simulation results.

WEEPPB013	Direct Wind Superconducting Corrector Magnets for the SuperKEKB IR	dipole, quadrupole, background, multipole	2191
	B. Parker, M. Anerella, J. Escallier, A.K. Ghosh, A.K. Jain, A. Marone, P. Wanderer BNL, Upton, Long Island, New York, USA Y. Arimoto, M. Iwasaki, N. Ohuchi, M. Tawada, K. Tsuchiya, H. Yamaoka, Z.G. Zong KEK, Ibaraki, Japan
	Upgrade of the KEKB asymmetric e⁺e⁻ collider for a forty-fold luminosity increase, denoted SuperKEKB, is now underway. For SuperKEKB the beam crossing angle is increased to provide separate focusing channels for the incoming and outgoing electron and positrons beams in new superconducting Interaction Region (IR) magnets. Two functional classes of superconducting corrector magnets are needed to meet SuperKEKB beam optics goals. Dipole, skew-dipole, skew-quadrupole and octupole coil windings will be inserted inside the bores of the main IR quadrupoles to make magnet center alignments, roll adjustments and non-linear optics corrections. A second class of high-order magnetic multipole corrector coils is needed to compensate the non-linear fringe field experienced by the circulating beam that passes just outside the main quadrupole coils that are closest to the Interaction Point (IP). Near the IP there is no space for magnetic yokes or other passive shielding to diminish the fringe field. At the time of this conference the SuperKEKB corrector magnet production will be under way. The SuperKEKB correction coil design and our production technique are reviewed in this paper.

WEPPD033	Design of 100 MeV Proton Beam Irradiation Facility for the PEFP 100 MeV Linac	proton, target, radiation, linac	2579
	S.P. Yun, Y.-S. Cho, J.-H. Jang, H.S. Kim, H.-J. Kwon, B.-S. Park, K.T. Seol, Y.-G. Song KAERI, Daejon, Republic of Korea
	Funding: This work is supported by the Ministry of Education, Science and Technology of the Korean Government. The Proton Engineering Frontier Project (PEFP) will install a 100-MeV proton linear accelerator at Gyeong-ju site. Two target rooms ( TR 103, TR 23) will be prepared in the beam commissioning stage for 20-MeV and 100-MeV proton beams, respectively. To design the irradiation equipment in TR 103, we have investigated general propagation shape and spatial distribution of proton beam by using Monte carlo method, when 100 MeV proton beam extracted from vacuum in the beam lines through beam window. On the basis of this result, we have designed beam irradiation components and their configuration. The beam irradiation facility consists of beam dump, support frame, sample support and beam current monitor. To minimize residual radioactivity induced by incident proton beam, the graphite was selected as the material of beam dump and the aluminum alloy was selected as material of other irradiation equipment. These residual radioactivity of equipment were estimated by Monte carlo method. In this paper, the details of this irradiation equipment design are presented.

WEPPR046	THz Bursting Thresholds Measured at the Metrology Light Source	storage-ring, electron, synchrotron, vacuum	3030
	M. Ries, J. Feikes, P.O. Schmid, G. Wüstefeld HZB, Berlin, Germany A. Hoehl PTB, Berlin, Germany
	At the Metrology Light Source (MLS) * of the Physikalisch-Technische Bundesanstalt (PTB) the bunch length can be varied by more than two orders of magnitude *. The bunch length manipulation is achieved by varying different machine parameters, such as rf-voltage amplitude up to 500 kV and the momentum compaction factor over three orders of magnitude. The subject of this article is the measurement of THz bursting thresholds at the MLS for different bunch lengths. B. Beckhoff et al., Phys. Status Solidi B 246, p. 1415 (2009) ** J. Feikes et al., Phys. Rev. ST Accel. Beams 14, 030705 (2011).

WEPPR052	Octupole Magnets for the Instability Damping at the J-PARC Main Ring	damping, resonance, sextupole, dynamic-aperture	3045
	S. Igarashi, T. Koseki, K. Ohmi, M.J. Shirakata, H. Someya, T. Toyama KEK, Ibaraki, Japan A. Ando J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	Octupole magnets have been installed for the instability damping at the J-PARC main ring. The transverse instability was observed during the injection and acceleration periods and caused the beam losses. The chromaticity tuning and bunch-by-bunch feedback system have been applied to suppress the instability. Octupole magnets were considered to create a larger amplitude dependent betatron tune shift and to supply additional option for the instability damping. The side effects of the dynamic aperture reduction and the resonances have been studied.

WEPPR068	Mitigation of Electron Cloud Instabilities in the LHC Using Sextupoles and Octupoles	electron, sextupole, damping, resonance	3084
	K.S.B. Li, G. Rumolo CERN, Geneva, Switzerland
	Coherent electron cloud instabilities pose a serious limitation for luminosity upgrades in the Large Hadron Collider (LHC) at CERN. In particular, when bunch spacings reach below 50 ns, electron cloud formation is enhanced which in turn drives beam instabilities. The beam can be stabilised by shifting the tune and by increasing the tune spread using sextupoles or octupoles, respectively. The resulting values for the chromaticity and the detuning parameters must be selected with care, however, in order not to run into head-tail instabilities or to considerably reduce the dynamic aperture. A simulation study has been launched to estimate the parameters necessary for stabilisation of the beam under the influence of electron clouds.

WEPPR069	Measurements and Simulations of Transverse Coupled-Bunch Instability Rise Times in the LHC	simulation, injection, feedback, impedance	3087
	N. Mounet, R. Alemany-Fernandez, W. Höfle, D. Jacquet, V. Kain, E. Métral, L. Ponce, S. Redaelli, G. Rumolo, R. Suykerbuyk, D. Valuch CERN, Geneva, Switzerland
	In the current configuration of the LHC, multibunch instabilities due to the beam-coupling impedance would be in principle a critical limitation if they were not damped by the transverse feedback. For the future operation of the machine, in particular at higher bunch intensities and/or higher number of bunches, one needs to make sure the coupled-bunch instability rise times are still manageable by the feedback system. Therefore, in May 2011 experiments were performed to measure those rise times and compare them with the results obtained from the LHC impedance model and the HEADTAIL wake fields simulation code. At injection energy, agreement turns out to be very good, while a larger discrepancy appears at top energy.

THPPD043	Radiation-tolerant Multipole Correction Coils for FRIB	quadrupole, radiation, sextupole, multipole	3608
	S.A. Kahn Muons, Inc, Batavia, USA R.C. Gupta BNL, Upton, Long Island, New York, USA
	Multipole correction insert coils with significant field strength are required inside the large aperture superconducting quadrupole magnets in the fragment separator section of the Facility for Rare Isotope Beams (FRIB). Correction coils made with copper do not create the required field and conventional low temperature superconductors are not practical in the fragment separator magnets which will operate at 40-50 K. The correction coils should be made of HTS as the main quadrupole coils are. There is a significant advantage to using HTS in these coils as it can withstand the high radiation and heat load that will be present. This paper will describe an innovative design suitable for coils with the complex end geometry of cylindrical coils. We will look at the forces on the corrector coils from the mail quadrupole fields and anticipate possible coil distortions.

THPPR055	Compact Gantry with Large Momentum Acceptance	kicker, proton, diagnostics, sextupole	4100
	W. Wan, D. Robin, A. Sessler, C. Sun LBNL, Berkeley, California, USA
	Rotatable Ion Beam Cancer Therapy (IBCT) delivery systems or gantries are the largest features in an ion beam therapy facility. They weight 100+ tons and require large (~3 story) heavily shielded rooms to house them. Reducing the size of ion beam gantries using high field One disadvantage of superconducting magnets is the difficulty of changing the fields quickly in order to adjust the beam momentum to scan the depth of penetration. In this paper we present a design of a gantry consisting of many combined function superconducting magnets that have a large enough momentum acceptance (> pm 10%) such that the magnets do not need to be changed while changing the beam energy.

Paper

Title

Other Keywords

Page

MOPPD049

The Layout of the High Energy Beam Transport for the European Spallation Source

target, linac, quadrupole, beam-transport

475

A.I.S. Holm, S.P. Møller, H.D. Thomsen
ISA, Aarhus, Denmark

The status of the High Energy Beam Transport (HEBT) line for the European Spallation Source (ESS) is presented. The HEBT brings the beam from the underground linac to the target at surface level. The main design objectives of the HEBT, such as space for upgrades, producing the desired target footprint etc. are discussed and the preferred design is shown. Large amplitude particles, a halo, are formed in the last part of the linac. Hence, every given value of the peak current density at the target is correlated with a certain power deposited outside the beam footprint. This correlation is studied and optimized. Furthermore, first studies of the vertical stability of the beam footprint and profile on target due to misalignment or mismatch of the incoming beam are made.

MOPPP079

Magnetic Tuning of the APS Wiggler as a Study for Tuning the NSLS-II Damping Wiggler

wiggler, multipole, damping, insertion

747

I. Vasserman, M. Abliz, E. Gluskin, E. Trakhtenberg, J.Z. Xu
ANL, Argonne, USA

Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357
A wide variety of tuning techniques has been developed and employed at Advanced Photon Source (APS) in the course of tuning insertion devices for use on the APS storage ring, the APS free electron laser, and in assisting with the LCLS undulator tuning. The tuning requirements for the National Synchrotron Source II (NSLS-II) damping wigglers are very demanding and include limits on the off-midplane field integrals that are new in the repertoire of undulator magnetic tuning. The goal of this study was to assess the applicability of existing tuning techniques to meeting the off-midplane requirements of NSLS-II. Tests were run using an available APS 8.5-cm-period wiggler. In addition to existing techniques, a special new shim design was tested. This report summarizes the results of these tests and shows that the wiggler can be tuned to the required specifications on the midplane over the requested ±15 mm in the horizontal direction. In the vertical direction, however, the specifications could only be met within ±0.5 mm. This falls short of the ±15 mm by ± 3 mm good-field region that is sought by NSLS-II.

TUOAA02

Focusing Charged Particle Beams Using Multipole Magnets in a Beam Transport Line

sextupole, multipole, target, focusing

1062

Y. Yuri, I. Ishibori, T. Ishizaka, S. Okumura, T. Yuyama
JAEA/TARRI, Gunma-ken, Japan

The intensity distribution of a charged-particle beam is transformed by applying the nonlinear focusing force of a multipole magnet. In this paper, the transformation of the transverse intensity distribution due to the second-order sextupole and third-order octupole focusing force in the beam transport line is explored. As a measure of the distribution transformation induced by the multipole magnets, the beam centroid displacement and the change of the beam size have been analytically derived using the distribution function of the beam. It is numerically verified how the transverse distribution of the beam is transformed by the multipole magnets. As an application of the distribution transformation by nonlinear focusing, a uniform beam can be formed from a Gaussian beam using multipole magnets. The current status and future plan of the experiment on the uniform-beam formation at the cyclotron facility in Japan Atomic Energy Agency will be shown.

Slides TUOAA02 [2.032 MB]

TUPPC005

Optimization of the SIS100 Nonlinear Magnet Scheme for Slow Extraction

extraction, sextupole, lattice, dynamic-aperture

1158

A. Saa Hernandez, M.M. Kirk, D. Ondreka, N. Pyka, S. Sorge, P.J. Spiller
GSI, Darmstadt, Germany

The SIS100 superconducting synchrotron was initially planned mainly for fast extraction of protons and heavy ions. Due to the delay of the construction of the SIS300 synchrotron, SIS100 has to be able to provide slowly extracted heavy ion beams to the experiments. To improve the robustness of the slow extraction from SIS100, a lattice review was performed, resulting in an optimization of the nonlinear magnet scheme. In the original scheme the Hardt condition cannot be established due to a collapse of the dynamic aperture caused by the chromatic sextupoles. In the optimized scheme the positions of the chromatic sextupoles are modified and octupoles are employed to compensate the second order effects of these sextupoles. In addition, the number of resonance sextupole magnets is reduced. With the new scheme, the Hardt condition can be established, leading to higher extraction efficiency. The separatrix can be freely adjusted, and closed orbit control is improved.

TUPPC077

Numerical Study of Beam Trapping in Stable Islands for Simple 2D Models of Betatronic Motion

emittance, simulation, resonance, extraction

1350

M. Giovannozzi, C. Hernalsteens
CERN, Geneva, Switzerland

An essential ingredient for the proposed Multi-Turn Extraction (MTE) at the CERN PS is the beam trapping in stable islands. The control of the trapping process is essential for the quality of the final beam in terms of intensity sharing and emittance. In this paper, the splitting process is studied quantitatively by means of numerical simulations performed on 2D model representing the horizontal non-linear betatronic motion. The results are reviewed and discussed in details.

TUPPC099

Optimization of Chromaticity Compensation and Dynamic Aperture in MEIC Collider Rings

sextupole, ion, dynamic-aperture, collider

1389

F. Lin, Y.S. Derbenev, V.S. Morozov, Y. Zhang
JLAB, Newport News, Virginia, USA
K.B. Beard
Muons, Inc, Batavia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Supported in part by US DOE STTR grant DE-SC0006272.
The conceptual design of the Medium-energy Electron-Ion Collider (MEIC) at Jefferson Lab relies on an ultra-small beta-star to achieve high luminosities of up to 10³⁴ cm^-2s⁻¹. A low-beta insertion for interaction regions unavoidably induces large chromatic effects that demand a proper compensation. The present approach of chromatic compensation in the MEIC collider rings is based on a local correction scheme using two symmetric chromatic compensation blocks that includes families of sextupoles, and are placed in a beam extension area on both sides of a collision point. It can simultaneously compensate the first order chromaticity and chromatic beam smear at the IP without inducing significant second order aberrations. In this paper, we investigate both the momentum acceptance and dynamic aperture in the MEIC ion collider ring by considering the aberration effects up to the third order, such as amplitude dependent tune shift. We also explore the compensation of the third order effects by introducing families of octupoles in the extended beam area.
Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Supported in part by US DOE STTR grant DE-SC0006272.

TUPPR017

Nonlinear Post-Linac Energy Collimation System for the Compact Linear Collider

sextupole, collimation, luminosity, simulation

1846

J. Resta-López, A. Faus-Golfe
IFIC, Valencia, Spain

Funding: FPA2010-21456-C02-01
The post-linac energy collimation system of the Compact Linear Collider (CLIC) has been designed to provide protection of the Beam Delivery System (BDS) against off-energy and mis-steered beams. The conventional baseline design consists of a two stage spoiler-absorber scheme. The CLIC energy collimators are required to withstand the impact of a full bunch train. This condition makes the energy collimator design very challenging, since the collimators have to deal with a total beam power of 14 MW at nominal energy and intensity. The increase of the transverse spot size at the collimators using nonlinear magnets could be a potential solution to guarantee the survivability of the collimators. In this paper we present an alternative nonlinear optics design for the CLIC energy collimation system. Possibilities for its optimization are discussed in view of performance simulation results.

WEEPPB013

Direct Wind Superconducting Corrector Magnets for the SuperKEKB IR

dipole, quadrupole, background, multipole

2191

B. Parker, M. Anerella, J. Escallier, A.K. Ghosh, A.K. Jain, A. Marone, P. Wanderer
BNL, Upton, Long Island, New York, USA
Y. Arimoto, M. Iwasaki, N. Ohuchi, M. Tawada, K. Tsuchiya, H. Yamaoka, Z.G. Zong
KEK, Ibaraki, Japan

Upgrade of the KEKB asymmetric e⁺e⁻ collider for a forty-fold luminosity increase, denoted SuperKEKB, is now underway. For SuperKEKB the beam crossing angle is increased to provide separate focusing channels for the incoming and outgoing electron and positrons beams in new superconducting Interaction Region (IR) magnets. Two functional classes of superconducting corrector magnets are needed to meet SuperKEKB beam optics goals. Dipole, skew-dipole, skew-quadrupole and octupole coil windings will be inserted inside the bores of the main IR quadrupoles to make magnet center alignments, roll adjustments and non-linear optics corrections. A second class of high-order magnetic multipole corrector coils is needed to compensate the non-linear fringe field experienced by the circulating beam that passes just outside the main quadrupole coils that are closest to the Interaction Point (IP). Near the IP there is no space for magnetic yokes or other passive shielding to diminish the fringe field. At the time of this conference the SuperKEKB corrector magnet production will be under way. The SuperKEKB correction coil design and our production technique are reviewed in this paper.

WEPPD033

Design of 100 MeV Proton Beam Irradiation Facility for the PEFP 100 MeV Linac

proton, target, radiation, linac

2579

S.P. Yun, Y.-S. Cho, J.-H. Jang, H.S. Kim, H.-J. Kwon, B.-S. Park, K.T. Seol, Y.-G. Song
KAERI, Daejon, Republic of Korea

Funding: This work is supported by the Ministry of Education, Science and Technology of the Korean Government.
The Proton Engineering Frontier Project (PEFP) will install a 100-MeV proton linear accelerator at Gyeong-ju site. Two target rooms ( TR 103, TR 23) will be prepared in the beam commissioning stage for 20-MeV and 100-MeV proton beams, respectively. To design the irradiation equipment in TR 103, we have investigated general propagation shape and spatial distribution of proton beam by using Monte carlo method, when 100 MeV proton beam extracted from vacuum in the beam lines through beam window. On the basis of this result, we have designed beam irradiation components and their configuration. The beam irradiation facility consists of beam dump, support frame, sample support and beam current monitor. To minimize residual radioactivity induced by incident proton beam, the graphite was selected as the material of beam dump and the aluminum alloy was selected as material of other irradiation equipment. These residual radioactivity of equipment were estimated by Monte carlo method. In this paper, the details of this irradiation equipment design are presented.

WEPPR046

THz Bursting Thresholds Measured at the Metrology Light Source

storage-ring, electron, synchrotron, vacuum

3030

M. Ries, J. Feikes, P.O. Schmid, G. Wüstefeld
HZB, Berlin, Germany
A. Hoehl
PTB, Berlin, Germany

At the Metrology Light Source (MLS) * of the Physikalisch-Technische Bundesanstalt (PTB) the bunch length can be varied by more than two orders of magnitude **. The bunch length manipulation is achieved by varying different machine parameters, such as rf-voltage amplitude up to 500 kV and the momentum compaction factor over three orders of magnitude. The subject of this article is the measurement of THz bursting thresholds at the MLS for different bunch lengths.
* B. Beckhoff et al., Phys. Status Solidi B 246, p. 1415 (2009)
** J. Feikes et al., Phys. Rev. ST Accel. Beams 14, 030705 (2011).

WEPPR052

Octupole Magnets for the Instability Damping at the J-PARC Main Ring

damping, resonance, sextupole, dynamic-aperture

3045

S. Igarashi, T. Koseki, K. Ohmi, M.J. Shirakata, H. Someya, T. Toyama
KEK, Ibaraki, Japan
A. Ando
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

Octupole magnets have been installed for the instability damping at the J-PARC main ring. The transverse instability was observed during the injection and acceleration periods and caused the beam losses. The chromaticity tuning and bunch-by-bunch feedback system have been applied to suppress the instability. Octupole magnets were considered to create a larger amplitude dependent betatron tune shift and to supply additional option for the instability damping. The side effects of the dynamic aperture reduction and the resonances have been studied.

WEPPR068

Mitigation of Electron Cloud Instabilities in the LHC Using Sextupoles and Octupoles

electron, sextupole, damping, resonance

3084

K.S.B. Li, G. Rumolo
CERN, Geneva, Switzerland

Coherent electron cloud instabilities pose a serious limitation for luminosity upgrades in the Large Hadron Collider (LHC) at CERN. In particular, when bunch spacings reach below 50 ns, electron cloud formation is enhanced which in turn drives beam instabilities. The beam can be stabilised by shifting the tune and by increasing the tune spread using sextupoles or octupoles, respectively. The resulting values for the chromaticity and the detuning parameters must be selected with care, however, in order not to run into head-tail instabilities or to considerably reduce the dynamic aperture. A simulation study has been launched to estimate the parameters necessary for stabilisation of the beam under the influence of electron clouds.

WEPPR069

Measurements and Simulations of Transverse Coupled-Bunch Instability Rise Times in the LHC

simulation, injection, feedback, impedance

3087

N. Mounet, R. Alemany-Fernandez, W. Höfle, D. Jacquet, V. Kain, E. Métral, L. Ponce, S. Redaelli, G. Rumolo, R. Suykerbuyk, D. Valuch
CERN, Geneva, Switzerland

In the current configuration of the LHC, multibunch instabilities due to the beam-coupling impedance would be in principle a critical limitation if they were not damped by the transverse feedback. For the future operation of the machine, in particular at higher bunch intensities and/or higher number of bunches, one needs to make sure the coupled-bunch instability rise times are still manageable by the feedback system. Therefore, in May 2011 experiments were performed to measure those rise times and compare them with the results obtained from the LHC impedance model and the HEADTAIL wake fields simulation code. At injection energy, agreement turns out to be very good, while a larger discrepancy appears at top energy.

THPPD043

Radiation-tolerant Multipole Correction Coils for FRIB

quadrupole, radiation, sextupole, multipole

3608

S.A. Kahn
Muons, Inc, Batavia, USA
R.C. Gupta
BNL, Upton, Long Island, New York, USA

Multipole correction insert coils with significant field strength are required inside the large aperture superconducting quadrupole magnets in the fragment separator section of the Facility for Rare Isotope Beams (FRIB). Correction coils made with copper do not create the required field and conventional low temperature superconductors are not practical in the fragment separator magnets which will operate at 40-50 K. The correction coils should be made of HTS as the main quadrupole coils are. There is a significant advantage to using HTS in these coils as it can withstand the high radiation and heat load that will be present. This paper will describe an innovative design suitable for coils with the complex end geometry of cylindrical coils. We will look at the forces on the corrector coils from the mail quadrupole fields and anticipate possible coil distortions.

THPPR055

Compact Gantry with Large Momentum Acceptance

kicker, proton, diagnostics, sextupole

4100

W. Wan, D. Robin, A. Sessler, C. Sun
LBNL, Berkeley, California, USA

Rotatable Ion Beam Cancer Therapy (IBCT) delivery systems or gantries are the largest features in an ion beam therapy facility. They weight 100+ tons and require large (~3 story) heavily shielded rooms to house them. Reducing the size of ion beam gantries using high field One disadvantage of superconducting magnets is the difficulty of changing the fields quickly in order to adjust the beam momentum to scan the depth of penetration. In this paper we present a design of a gantry consisting of many combined function superconducting magnets that have a large enough momentum acceptance (> pm 10%) such that the magnets do not need to be changed while changing the beam energy.