IPAC2012 - List of Authors (Holzer, B.J.)

Paper	Title	Page
MOPPC013	Optics and Lattice Optimizations for the LHC Upgrade Project	151
	B. Dalena CEA/IRFU, Gif-sur-Yvette, France R. Appleby UMAN, Manchester, United Kingdom A.V. Bogomyagkov BINP SB RAS, Novosibirsk, Russia A. Chancé, J. Payet CEA/DSM/IRFU, France R. De Maria, B.J. Holzer CERN, Geneva, Switzerland A. Faus-Golfe, J. Resta-López IFIC, Valencia, Spain K.M. Hock, M. Korostelev, L.N.S. Thompson, A. Wolski Cockcroft Institute, Warrington, Cheshire, United Kingdom C. Milardi INFN/LNF, Frascati (Roma), Italy
	The luminosity upgrade of the LHC collider at CERN is based on a strong focusing scheme to reach lowest values of the beta function at the collision points. Several issues have to be addressed in this context, that are considered as mid term goals for the optimisation of the lattice and beam optics: Firstly a number of beam optics have been developed to establish a baseline for the hardware R&D, and to define the specifications for the new magnets that will be needed, in Nb3Sn and in NbTi technology. Secondly, the need for sufficient flexibility of the beam optics especially for smallest β^* values has to be investigated as well as the need for a smooth transition between the injection and the collision optics. Finally the performance of the optics based on flat and round beams has to be compared and different ways have to be studied to optimise the chromatic correction, including the study of local correction schemes. This paper presents the status of this work, which is a result of an international collaboration, and summarises the main parameters that are foreseen to reach the HL-LHC luminosity goal.

MOPPC017	Causes and Solutions for Emittance Blow-Up During the LHC Cycle	160
	M. Kuhn Uni HH, Hamburg, Germany G. Arduini, B.J. Holzer, J.M. Jowett, V. Kain, F. Roncarolo, M. Schaumann, R. Versteegen, J. Wenninger CERN, Geneva, Switzerland
	Emittance measurements during the run 2011 indicated a blow-up of 20 % to 30 % from LHC injection to collisions. At the LHC design stage the total allowed emittance increase through the cycle was set to 7 %. One of the goals of the 2012 LHC run is therefore to understand and counteract the blow-up. Emittance growth measurements through the LHC cycle along with correlations with possible sources are presented in this paper. Solutions are proposed where possible. The emittance determination accuracy relies on the knowledge of the beam optics and on the present performance of the transverse profile monitors. Possible improvements of the diagnostics and of the related data analysis are also discussed.

TUPPC036	Integration with the LHC of Electron Interaction Region Optics for a Ring-ring LHeC	1239
	L.N.S. Thompson Cockcroft Institute, Warrington, Cheshire, United Kingdom R. Appleby UMAN, Manchester, United Kingdom N.R. Bernard ETH, Zurich, Switzerland H. Burkhardt, B.J. Holzer CERN, Geneva, Switzerland M. Fitterer KIT, Karlsruhe, Germany M. Klein The University of Liverpool, Liverpool, United Kingdom P. Kostka DESY Zeuthen, Zeuthen, Germany
	The Large Hadron Electron Collider (LHeC) project is a proposal to study e-p and e-A interactions at the LHC. One design uses an electron synchrotron to collide a 60GeV e± beam with the 7TeV proton beam. Designing a new accelerator around the existing LHC machine poses unique challenges, particularly in the interaction region (IR). The electron beam must be quickly separated from the proton beam after the interaction point (IP) to avoid beam-beam effects, while not significantly reducing luminosity or producing large amounts of synchrotron radiation. The proton beam must pass through the electron optics, while the electron beam must avoid the proton optics. The long straight section requires bending in both planes to counteract the IP crossing angle and to displace the beam vertically from the electron machine to the proton IP. An achromatic bending scheme is used in the vertical plane to eliminate dispersion at the IP and provide an optics which is well matched to the LHeC ring lattice. The interaction region and long straight section design is presented and detailed, and the design process and principles discussed.

TUPPC037	Update on LHeC Ring-Ring Optics	1242
	M. Fitterer KIT, Karlsruhe, Germany O.S. Brüning, H. Burkhardt, B.J. Holzer, J.M. Jowett CERN, Geneva, Switzerland M. Klein The University of Liverpool, Liverpool, United Kingdom
	An update of the LHeC Ring-Ring optics is presented which accounts for chromatic corrections and more flexibility in the tune adjustment.

TUPPC038	Interaction Region Optics for the Non-Interacting LHC Proton Beam at the LHeC	1245
	L.N.S. Thompson Cockcroft Institute, Warrington, Cheshire, United Kingdom R. Appleby UMAN, Manchester, United Kingdom O.S. Brüning, B.J. Holzer CERN, Geneva, Switzerland M. Klein The University of Liverpool, Liverpool, United Kingdom P. Kostka DESY Zeuthen, Zeuthen, Germany
	The Large Hadron Electron Collider project is a proposal to study e-p and e-A interactions at the LHC. Two electron accelerator designs are being studied; a linac and a synchrotron. In the synchrotron option, a 60GeV electron beam is collided with one of the LHC proton beams to provide high luminosity TeV-scale interactions. The interaction region for this scheme is complex and introduces a series of challenges due to the integration of the two machines. One of these is the optics of the second non-interacting proton beam. The second proton beam must not interfere with the LHeC experiment, but simultaneous running of the remaining LHC experiments requires that this beam must still circulate relatively undisturbed. This paper discusses methods to solve these challenges for the electron synchrotron design.

TUPPC039	Synchrotron Radiation Studies for a Ring-Ring LHeC Interaction Region and Long Straight Section	1248
	L.N.S. Thompson Cockcroft Institute, Warrington, Cheshire, United Kingdom R. Appleby UMAN, Manchester, United Kingdom N.R. Bernard ETH, Zurich, Switzerland O.S. Brüning, B.J. Holzer CERN, Geneva, Switzerland M. Klein The University of Liverpool, Liverpool, United Kingdom P. Kostka DESY Zeuthen, Zeuthen, Germany B. Nagorny DESY, Hamburg, Germany
	The Large Hadron Electron Collider project is a proposal to study e-p and e-A interactions at the LHC. In the design for an electron synchrotron (alternative designs for a linac are also under development), a 60GeV e± beam is collided with a 7TeV LHC proton beam to produce TeV-scale collisions. Despite being much lower energy than the proton beam, the electron beam is high enough energy to produce significant amounts of synchrotron radiation (SR). This places strong constraints on beam optics and bending. In particular challenges arise with the complex geometry required by the long straight section (LSS) and interaction region (IR). This includes the coupled nature of the proton and electron optics, as SR produced by the electron beam must not be allowed to quench the superconducting proton magnets or create problems with beam-gas backgrounds. Despite this, the electron beam must be deflected significantly within the IR to produce sufficient separation from the proton beam.

TUPPR075	Challenges for the Magnet System of LHeC	1996
	S. Russenschuck, B.J. Holzer, G. Kirby, A. Milanese, R. Tomás, D. Tommasini, F. Zimmermann CERN, Geneva, Switzerland
	The main challenges for the normal conducting magnet system are the very compact, low field, and high precision magnets for the ring-ring option and their rapid installation in the crowded LHC tunnel. The superconducting triplet magnets require strong gradients for the protons in close vicinity of a field-free region for the electrons. The field requirements for the ring-ring option allow a number of different magnet designs using the well-proven Nb-Ti superconductor technology and making use of the cable development for the LHC. The separation distance between the electron and proton beams in Q1 requires a half-aperture quadrupole design to limit the overall synchrotron radiation power emitted by the bending of the electron beam. The requirements in terms of aperture and field gradient are more difficult to obtain for the Linac-Ring option. Consequently we present the limitations for the field gradient and septum size achievable with both Nb-Ti and Nb3Sn superconducting technologies.

THPPP018	Operation of the LHC at High Luminosity and High Stored Energy	3767
	J. Wenninger, R. Alemany-Fernandez, G. Arduini, R.W. Assmann, B.J. Holzer, E.B. Holzer, V. Kain, M. Lamont, A. Macpherson, G. Papotti, M. Pojer, L. Ponce, S. Redaelli, M. Solfaroli Camillocci, J.A. Uythoven, W. Venturini Delsolaro CERN, Geneva, Switzerland
	In 2011 the operation of the Large Hadron Collider LHC entered its first year of high luminosity production at a beam energy of 3.5 TeV. In the first months of 2011 the number of bunches was progressively increased to 1380, followed by a reduction of the transverse emittance, an increase of the bunch population and a reduction of the betatron function at the collision points. The performance improvements steps that were accumulated in 2011 eventually brought the peak luminosity to 3.6·10³³ cm^-2s⁻¹. The integrated luminosity delivered to each of the high luminosity experiments amounted to 5.6 fb-1, a factor of 5 above the initial target defined in 2010. The operational experience with high intensity and high luminosity at the LHC will be presented here, together with the issues that had to be tackled on the road to high intensity and luminosity.

Paper

Title

Page

Optics and Lattice Optimizations for the LHC Upgrade Project

151

B. Dalena
CEA/IRFU, Gif-sur-Yvette, France
R. Appleby
UMAN, Manchester, United Kingdom
A.V. Bogomyagkov
BINP SB RAS, Novosibirsk, Russia
A. Chancé, J. Payet
CEA/DSM/IRFU, France
R. De Maria, B.J. Holzer
CERN, Geneva, Switzerland
A. Faus-Golfe, J. Resta-López
IFIC, Valencia, Spain
K.M. Hock, M. Korostelev, L.N.S. Thompson, A. Wolski
Cockcroft Institute, Warrington, Cheshire, United Kingdom
C. Milardi
INFN/LNF, Frascati (Roma), Italy

The luminosity upgrade of the LHC collider at CERN is based on a strong focusing scheme to reach lowest values of the beta function at the collision points. Several issues have to be addressed in this context, that are considered as mid term goals for the optimisation of the lattice and beam optics: Firstly a number of beam optics have been developed to establish a baseline for the hardware R&D, and to define the specifications for the new magnets that will be needed, in Nb3Sn and in NbTi technology. Secondly, the need for sufficient flexibility of the beam optics especially for smallest β^* values has to be investigated as well as the need for a smooth transition between the injection and the collision optics. Finally the performance of the optics based on flat and round beams has to be compared and different ways have to be studied to optimise the chromatic correction, including the study of local correction schemes. This paper presents the status of this work, which is a result of an international collaboration, and summarises the main parameters that are foreseen to reach the HL-LHC luminosity goal.

MOPPC017

Causes and Solutions for Emittance Blow-Up During the LHC Cycle

160

M. Kuhn
Uni HH, Hamburg, Germany
G. Arduini, B.J. Holzer, J.M. Jowett, V. Kain, F. Roncarolo, M. Schaumann, R. Versteegen, J. Wenninger
CERN, Geneva, Switzerland

Emittance measurements during the run 2011 indicated a blow-up of 20 % to 30 % from LHC injection to collisions. At the LHC design stage the total allowed emittance increase through the cycle was set to 7 %. One of the goals of the 2012 LHC run is therefore to understand and counteract the blow-up. Emittance growth measurements through the LHC cycle along with correlations with possible sources are presented in this paper. Solutions are proposed where possible. The emittance determination accuracy relies on the knowledge of the beam optics and on the present performance of the transverse profile monitors. Possible improvements of the diagnostics and of the related data analysis are also discussed.

TUPPC036

Integration with the LHC of Electron Interaction Region Optics for a Ring-ring LHeC

1239

L.N.S. Thompson
Cockcroft Institute, Warrington, Cheshire, United Kingdom
R. Appleby
UMAN, Manchester, United Kingdom
N.R. Bernard
ETH, Zurich, Switzerland
H. Burkhardt, B.J. Holzer
CERN, Geneva, Switzerland
M. Fitterer
KIT, Karlsruhe, Germany
M. Klein
The University of Liverpool, Liverpool, United Kingdom
P. Kostka
DESY Zeuthen, Zeuthen, Germany

The Large Hadron Electron Collider (LHeC) project is a proposal to study e-p and e-A interactions at the LHC. One design uses an electron synchrotron to collide a 60GeV e± beam with the 7TeV proton beam. Designing a new accelerator around the existing LHC machine poses unique challenges, particularly in the interaction region (IR). The electron beam must be quickly separated from the proton beam after the interaction point (IP) to avoid beam-beam effects, while not significantly reducing luminosity or producing large amounts of synchrotron radiation. The proton beam must pass through the electron optics, while the electron beam must avoid the proton optics. The long straight section requires bending in both planes to counteract the IP crossing angle and to displace the beam vertically from the electron machine to the proton IP. An achromatic bending scheme is used in the vertical plane to eliminate dispersion at the IP and provide an optics which is well matched to the LHeC ring lattice. The interaction region and long straight section design is presented and detailed, and the design process and principles discussed.

TUPPC037

Update on LHeC Ring-Ring Optics

1242

M. Fitterer
KIT, Karlsruhe, Germany
O.S. Brüning, H. Burkhardt, B.J. Holzer, J.M. Jowett
CERN, Geneva, Switzerland
M. Klein
The University of Liverpool, Liverpool, United Kingdom

An update of the LHeC Ring-Ring optics is presented which accounts for chromatic corrections and more flexibility in the tune adjustment.

TUPPC038

Interaction Region Optics for the Non-Interacting LHC Proton Beam at the LHeC

1245

L.N.S. Thompson
Cockcroft Institute, Warrington, Cheshire, United Kingdom
R. Appleby
UMAN, Manchester, United Kingdom
O.S. Brüning, B.J. Holzer
CERN, Geneva, Switzerland
M. Klein
The University of Liverpool, Liverpool, United Kingdom
P. Kostka
DESY Zeuthen, Zeuthen, Germany

The Large Hadron Electron Collider project is a proposal to study e-p and e-A interactions at the LHC. Two electron accelerator designs are being studied; a linac and a synchrotron. In the synchrotron option, a 60GeV electron beam is collided with one of the LHC proton beams to provide high luminosity TeV-scale interactions. The interaction region for this scheme is complex and introduces a series of challenges due to the integration of the two machines. One of these is the optics of the second non-interacting proton beam. The second proton beam must not interfere with the LHeC experiment, but simultaneous running of the remaining LHC experiments requires that this beam must still circulate relatively undisturbed. This paper discusses methods to solve these challenges for the electron synchrotron design.

TUPPC039

Synchrotron Radiation Studies for a Ring-Ring LHeC Interaction Region and Long Straight Section

1248

L.N.S. Thompson
Cockcroft Institute, Warrington, Cheshire, United Kingdom
R. Appleby
UMAN, Manchester, United Kingdom
N.R. Bernard
ETH, Zurich, Switzerland
O.S. Brüning, B.J. Holzer
CERN, Geneva, Switzerland
M. Klein
The University of Liverpool, Liverpool, United Kingdom
P. Kostka
DESY Zeuthen, Zeuthen, Germany
B. Nagorny
DESY, Hamburg, Germany

The Large Hadron Electron Collider project is a proposal to study e-p and e-A interactions at the LHC. In the design for an electron synchrotron (alternative designs for a linac are also under development), a 60GeV e± beam is collided with a 7TeV LHC proton beam to produce TeV-scale collisions. Despite being much lower energy than the proton beam, the electron beam is high enough energy to produce significant amounts of synchrotron radiation (SR). This places strong constraints on beam optics and bending. In particular challenges arise with the complex geometry required by the long straight section (LSS) and interaction region (IR). This includes the coupled nature of the proton and electron optics, as SR produced by the electron beam must not be allowed to quench the superconducting proton magnets or create problems with beam-gas backgrounds. Despite this, the electron beam must be deflected significantly within the IR to produce sufficient separation from the proton beam.

TUPPR075

Challenges for the Magnet System of LHeC

1996

S. Russenschuck, B.J. Holzer, G. Kirby, A. Milanese, R. Tomás, D. Tommasini, F. Zimmermann
CERN, Geneva, Switzerland

The main challenges for the normal conducting magnet system are the very compact, low field, and high precision magnets for the ring-ring option and their rapid installation in the crowded LHC tunnel. The superconducting triplet magnets require strong gradients for the protons in close vicinity of a field-free region for the electrons. The field requirements for the ring-ring option allow a number of different magnet designs using the well-proven Nb-Ti superconductor technology and making use of the cable development for the LHC. The separation distance between the electron and proton beams in Q1 requires a half-aperture quadrupole design to limit the overall synchrotron radiation power emitted by the bending of the electron beam. The requirements in terms of aperture and field gradient are more difficult to obtain for the Linac-Ring option. Consequently we present the limitations for the field gradient and septum size achievable with both Nb-Ti and Nb3Sn superconducting technologies.

THPPP018

Operation of the LHC at High Luminosity and High Stored Energy

3767

J. Wenninger, R. Alemany-Fernandez, G. Arduini, R.W. Assmann, B.J. Holzer, E.B. Holzer, V. Kain, M. Lamont, A. Macpherson, G. Papotti, M. Pojer, L. Ponce, S. Redaelli, M. Solfaroli Camillocci, J.A. Uythoven, W. Venturini Delsolaro
CERN, Geneva, Switzerland

In 2011 the operation of the Large Hadron Collider LHC entered its first year of high luminosity production at a beam energy of 3.5 TeV. In the first months of 2011 the number of bunches was progressively increased to 1380, followed by a reduction of the transverse emittance, an increase of the bunch population and a reduction of the betatron function at the collision points. The performance improvements steps that were accumulated in 2011 eventually brought the peak luminosity to 3.6·10³³ cm^-2s⁻¹. The integrated luminosity delivered to each of the high luminosity experiments amounted to 5.6 fb-1, a factor of 5 above the initial target defined in 2010. The operational experience with high intensity and high luminosity at the LHC will be presented here, together with the issues that had to be tackled on the road to high intensity and luminosity.