IPAC2011 - List of Authors (Papaphilippou, Y.)

Paper	Title	Page
MOPS010	Experimental Studies with Low Transition Energy Optics in the SPS	613
	H. Bartosik, T. Argyropoulos, T. Bohl, S. Cettour Cave, K. Cornelis, J. Esteban Muller, Y. Papaphilippou, G. Rumolo, B. Salvant, E.N. Shaposhnikova, J. Wenninger CERN, Geneva, Switzerland
	The optics of the SPS can be tuned to lower transition energy such that the slippage factor at injection is raised by a factor of almost 3. From theory, an increase of the intensity thresholds for transverse mode coupling, longitudinal coupled bunch and longitudinal instabilities due to the loss of Landau damping can be expected. In this paper, experimental studies in the SPS with single bunches of protons with intensities of up to 3.5·10¹¹ p/b on the flat bottom and at 450 GeV/c are presented. Longitudinal instabilities were studied with LHC-type beams with 50~ns spacing and injected intensities up to 1.8·10¹¹ p/b. The measurements address the increase of intensity thresholds and the achievable transverse emittances in the new low gamma transition optics with respect to the nominal SPS optics. The obtained results are compared with numerical simulations.

MOPS011	Impact of Low Transition Energy Optics to the Electron Cloud Instability of LHC Beams in the SPS	616
	H. Bartosik, E. Benedetto, K.S.B. Li, Y. Papaphilippou, G. Rumolo CERN, Geneva, Switzerland
	One of the main limitations for high intensity multi-bunch LHC proton beams in the SPS is imposed by electron cloud instabilities. A new optics of the SPS with lower transition energy was implemented and successfully tested in machine studies. The significant increase of the slippage factor that it provides at injection energy results in the expected increase of the single bunch instability thresholds. In this paper, the impact of this new optics on the electron cloud instability threshold is estimated by using numerical simulations, taking into account the change of the optics functions and the faster synchrotron motion due to the reduced transition energy.

MOPS012	Optics Considerations for Lowering Transition Energy in the SPS	619
	H. Bartosik, G. Arduini, Y. Papaphilippou CERN, Geneva, Switzerland
	Beam stability for high intensity LHC beams in the SPS can be improved by increasing the slippage factor, i.e. reducing the transition energy. In this paper, possible ways of modifying the optics of the SPS for lower transition energy are reviewed. In particular, a threefold increase of the slippage factor at injection can be achieved by decreasing the integer part of the tunes by 6 units. The properties of this new low-transition optics are compared with the nominal SPS optics, including working point and resonance behavior. Possible limitations are discussed.

TUPC046	Alignment Tolerances for Vertical Emittance	1102
	K.P. Wootton, R.P. Rassool, G. Taylor The University of Melbourne, Melbourne, Australia M.J. Boland, R.T. Dowd, G. LeBlanc, Y.E. Tan ASCo, Clayton, Victoria, Australia Y. Papaphilippou CERN, Geneva, Switzerland
	Alignment tolerances for the CLIC main damping ring magnetic lattice elements are presented. Tolerances are defined by the design equilibrium vertical emittance of 1 pm rad. The sensitivity of the uncorrected lattice to magnet misalignments is presented. Misalignments considered included quadrupole vertical offsets and rolls, sextupole vertical offsets, and main dipole rolls. Seeded simulations were conducted in MAD-X, and compared with expectation values calculated from theory. The lattice was found to be sensitive to betatron coupling as a result of sextupole vertical offsets in the arcs. Alignment tolerances, BPM and corrector requirements are presented also. For the same misalignment types, the equilibrium emittance of the corrected lattice is simulated. These are compared with expectation values calculated from theory. The vertical alignment tolerance of arc sextupoles is again demanding.

TUPC049	Optics considerations for the Delay Loop in the CLIC Damping Rings Complex	1108
	P. Zisopoulos, F. Antoniou, H. Bartosik, Y. Papaphilippou CERN, Geneva, Switzerland
	For the recombination of the two trains coming from the CLIC damping rings, a delay loop will be used in order to obtain the nominal 0.5~ns bunch spacing. The optics design of the loop is based upon an isochronous ring, in order to preserve the longitudinal beam distribution. Analytical expressions for achieving isochronous conditions in high order for Theoretical Minimum Emittance cells are obtained. A parametrisation of the quadrupole settings for achieving these conditions is presented, along with general considerations regarding the choice of bending magnet characteristics.

WEPC080	Non-linear Dynamics Optimization of the CLIC Damping Rings	2205
	Y. Renier, F. Antoniou, H. Bartosik, Y. Papaphilippou CERN, Geneva, Switzerland K.P. Wootton The University of Melbourne, Melbourne, Australia
	Non-linear dynamics studies are undertaken in order to optimize the dynamic aperture of the CLIC damping rings. In this respect, advanced methods such as frequency map and resonance driving term analysis are used in order to explore the working point space with respect to single particle stability. The impact of magnet errors and misalignments, and in particular, the effect of the super-conducting damping wigglers is evaluated. Additional considerations for the working point choice are presented.

Paper

Title

Page

Experimental Studies with Low Transition Energy Optics in the SPS

613

H. Bartosik, T. Argyropoulos, T. Bohl, S. Cettour Cave, K. Cornelis, J. Esteban Muller, Y. Papaphilippou, G. Rumolo, B. Salvant, E.N. Shaposhnikova, J. Wenninger
CERN, Geneva, Switzerland

The optics of the SPS can be tuned to lower transition energy such that the slippage factor at injection is raised by a factor of almost 3. From theory, an increase of the intensity thresholds for transverse mode coupling, longitudinal coupled bunch and longitudinal instabilities due to the loss of Landau damping can be expected. In this paper, experimental studies in the SPS with single bunches of protons with intensities of up to 3.5·10¹¹ p/b on the flat bottom and at 450 GeV/c are presented. Longitudinal instabilities were studied with LHC-type beams with 50~ns spacing and injected intensities up to 1.8·10¹¹ p/b. The measurements address the increase of intensity thresholds and the achievable transverse emittances in the new low gamma transition optics with respect to the nominal SPS optics. The obtained results are compared with numerical simulations.

MOPS011

Impact of Low Transition Energy Optics to the Electron Cloud Instability of LHC Beams in the SPS

616

H. Bartosik, E. Benedetto, K.S.B. Li, Y. Papaphilippou, G. Rumolo
CERN, Geneva, Switzerland

One of the main limitations for high intensity multi-bunch LHC proton beams in the SPS is imposed by electron cloud instabilities. A new optics of the SPS with lower transition energy was implemented and successfully tested in machine studies. The significant increase of the slippage factor that it provides at injection energy results in the expected increase of the single bunch instability thresholds. In this paper, the impact of this new optics on the electron cloud instability threshold is estimated by using numerical simulations, taking into account the change of the optics functions and the faster synchrotron motion due to the reduced transition energy.

MOPS012

Optics Considerations for Lowering Transition Energy in the SPS

619

H. Bartosik, G. Arduini, Y. Papaphilippou
CERN, Geneva, Switzerland

Beam stability for high intensity LHC beams in the SPS can be improved by increasing the slippage factor, i.e. reducing the transition energy. In this paper, possible ways of modifying the optics of the SPS for lower transition energy are reviewed. In particular, a threefold increase of the slippage factor at injection can be achieved by decreasing the integer part of the tunes by 6 units. The properties of this new low-transition optics are compared with the nominal SPS optics, including working point and resonance behavior. Possible limitations are discussed.

TUPC046

Alignment Tolerances for Vertical Emittance

1102

K.P. Wootton, R.P. Rassool, G. Taylor
The University of Melbourne, Melbourne, Australia
M.J. Boland, R.T. Dowd, G. LeBlanc, Y.E. Tan
ASCo, Clayton, Victoria, Australia
Y. Papaphilippou
CERN, Geneva, Switzerland

Alignment tolerances for the CLIC main damping ring magnetic lattice elements are presented. Tolerances are defined by the design equilibrium vertical emittance of 1 pm rad. The sensitivity of the uncorrected lattice to magnet misalignments is presented. Misalignments considered included quadrupole vertical offsets and rolls, sextupole vertical offsets, and main dipole rolls. Seeded simulations were conducted in MAD-X, and compared with expectation values calculated from theory. The lattice was found to be sensitive to betatron coupling as a result of sextupole vertical offsets in the arcs. Alignment tolerances, BPM and corrector requirements are presented also. For the same misalignment types, the equilibrium emittance of the corrected lattice is simulated. These are compared with expectation values calculated from theory. The vertical alignment tolerance of arc sextupoles is again demanding.

TUPC049

Optics considerations for the Delay Loop in the CLIC Damping Rings Complex

1108

P. Zisopoulos, F. Antoniou, H. Bartosik, Y. Papaphilippou
CERN, Geneva, Switzerland

For the recombination of the two trains coming from the CLIC damping rings, a delay loop will be used in order to obtain the nominal 0.5~ns bunch spacing. The optics design of the loop is based upon an isochronous ring, in order to preserve the longitudinal beam distribution. Analytical expressions for achieving isochronous conditions in high order for Theoretical Minimum Emittance cells are obtained. A parametrisation of the quadrupole settings for achieving these conditions is presented, along with general considerations regarding the choice of bending magnet characteristics.

WEPC080

Non-linear Dynamics Optimization of the CLIC Damping Rings

2205

Y. Renier, F. Antoniou, H. Bartosik, Y. Papaphilippou
CERN, Geneva, Switzerland
K.P. Wootton
The University of Melbourne, Melbourne, Australia

Non-linear dynamics studies are undertaken in order to optimize the dynamic aperture of the CLIC damping rings. In this respect, advanced methods such as frequency map and resonance driving term analysis are used in order to explore the working point space with respect to single particle stability. The impact of magnet errors and misalignments, and in particular, the effect of the super-conducting damping wigglers is evaluated. Additional considerations for the working point choice are presented.