IPAC2011 - List of Authors (Lefevre, T.)

Paper	Title	Page
MOPC150	High Charge PHIN Photo Injector at CERN with Fast Phase Switching within the Bunch Train for Beam Combination	430
	M. Divall Csatari, A. Andersson, B. Bolzon, E. Bravin, E. Chevallay, A.E. Dabrowski, S. Döbert, V. Fedosseev, C. Heßler, T. Lefèvre, S. Livesley, R. Losito, O. Mete, M. Olvegård, M. Petrarca, A. Rabiller CERN, Geneva, Switzerland A. Drozdy BUTE, Budapest, Hungary D. Egger EPFL, Lausanne, Switzerland
	The high charge PHIN photo-injector was developed within the frame of the European CARE program to provide an alternative to the drive beam thermionic gun in CTF3 (CLIC Test Facility) at CERN. In PHIN 1908 bunches are delivered with bunch spacing of 1.5 GHz and 2.33 nC charge per bunch. Furthermore the drive beam generated by CTF3 requires several fast 180 deg phase-shifts with respect to the 1.5 GHz bunch repetition frequency in order to allow the beam combination scheme developed at CTF3. A total of 8 sub-trains, each 140 ns long and shifted in phase with respect to each other, have to be produced with very high phase and amplitude stability. A novel fiber modulator based phase-switching technique developed on the laser system provides this phase-shift between two consecutive pulses much faster and cleaner than the base line scheme, where a thermionic electron gun and sub-harmonic bunching are used. The paper describes the fiber-based switching system and the measurements verifying the scheme. Stability measurements are presented for the phase-coded system. The paper also discusses the latest 8nC charge production and cathode life-time studies on Cs2Te.

TUPC048	First Measurement Results of the LHC Longitudinal Density Monitor	1105
	A. Jeff, M. Andersen, A. Boccardi, S. Bozyigit, E. Bravin, T. Lefèvre, A. Rabiller, F. Roncarolo CERN, Geneva, Switzerland A.S. Fisher SLAC, Menlo Park, California, USA C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: The primary author is funded by the E.U. under the DITANET Marie Curie network. Knowledge of the longitudinal distribution of particles is important for various aspects of accelerator operation, for example to check the injection quality and to characterize the development of ghost bunches before and during the physics periods. A new detector, the LHC Longitudinal Density Monitor (LDM) is a single-photon counting system measuring synchrotron light by means of an avalanche photodiode detector. The unprecedented energies reached in the LHC allow synchrotron light diagnostics to be used with both protons and heavy ions. The LDM is able to longitudinally profile the whole ring with a resolution close to the target of 50 ps. On-line correction for the effects of the detector deadtime, pile-up and afterpulsing allow a dynamic range of 10⁵ to be achieved. The LDM operated during the 2010 lead ion run and during 2011 with protons. Measurements from both runs are presented in this contribution along with an analysis of the LDM performance and an outlook for future upgrades.

TUPC139	Overview of the CLIC Beam Instrumentation	1350
	T. Lefèvre CERN, Geneva, Switzerland
	Driven by beam dynamic considerations the Compact Linear Collider (CLIC) is expected to require extremely tight tolerances on most beam parameters. An important milestone was reached in 2011 with the completion of the CLIC conceptual design report. In this context the requirements for CLIC beam instrumentation has been reviewed and studied in detail for the whole accelerator complex with the aim of demonstrating feasibility. A preliminary choice has been made for every CLIC instrument, serving as a baseline scenario for the next phase of the project which will concentrate on the detailed design, engineering and test of CLIC devices. Whenever possible existing solutions have been studied, focusing on any improvements necessary to meet the CLIC performance criteria. When no such devices exists, or if cost considerations come into play, new technologies have been under study. Several prototypes are already well advanced and are currently under test. This paper presents an overview of CLIC beam instrumentation, the possible reach of their performance and an outlook on future developments.

Paper

Title

Page

High Charge PHIN Photo Injector at CERN with Fast Phase Switching within the Bunch Train for Beam Combination

430

M. Divall Csatari, A. Andersson, B. Bolzon, E. Bravin, E. Chevallay, A.E. Dabrowski, S. Döbert, V. Fedosseev, C. Heßler, T. Lefèvre, S. Livesley, R. Losito, O. Mete, M. Olvegård, M. Petrarca, A. Rabiller
CERN, Geneva, Switzerland
A. Drozdy
BUTE, Budapest, Hungary
D. Egger
EPFL, Lausanne, Switzerland

The high charge PHIN photo-injector was developed within the frame of the European CARE program to provide an alternative to the drive beam thermionic gun in CTF3 (CLIC Test Facility) at CERN. In PHIN 1908 bunches are delivered with bunch spacing of 1.5 GHz and 2.33 nC charge per bunch. Furthermore the drive beam generated by CTF3 requires several fast 180 deg phase-shifts with respect to the 1.5 GHz bunch repetition frequency in order to allow the beam combination scheme developed at CTF3. A total of 8 sub-trains, each 140 ns long and shifted in phase with respect to each other, have to be produced with very high phase and amplitude stability. A novel fiber modulator based phase-switching technique developed on the laser system provides this phase-shift between two consecutive pulses much faster and cleaner than the base line scheme, where a thermionic electron gun and sub-harmonic bunching are used. The paper describes the fiber-based switching system and the measurements verifying the scheme. Stability measurements are presented for the phase-coded system. The paper also discusses the latest 8nC charge production and cathode life-time studies on Cs2Te.

TUPC048

First Measurement Results of the LHC Longitudinal Density Monitor

1105

A. Jeff, M. Andersen, A. Boccardi, S. Bozyigit, E. Bravin, T. Lefèvre, A. Rabiller, F. Roncarolo
CERN, Geneva, Switzerland
A.S. Fisher
SLAC, Menlo Park, California, USA
C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: The primary author is funded by the E.U. under the DITANET Marie Curie network.
Knowledge of the longitudinal distribution of particles is important for various aspects of accelerator operation, for example to check the injection quality and to characterize the development of ghost bunches before and during the physics periods. A new detector, the LHC Longitudinal Density Monitor (LDM) is a single-photon counting system measuring synchrotron light by means of an avalanche photodiode detector. The unprecedented energies reached in the LHC allow synchrotron light diagnostics to be used with both protons and heavy ions. The LDM is able to longitudinally profile the whole ring with a resolution close to the target of 50 ps. On-line correction for the effects of the detector deadtime, pile-up and afterpulsing allow a dynamic range of 10⁵ to be achieved. The LDM operated during the 2010 lead ion run and during 2011 with protons. Measurements from both runs are presented in this contribution along with an analysis of the LDM performance and an outlook for future upgrades.

TUPC139

Overview of the CLIC Beam Instrumentation

1350

T. Lefèvre
CERN, Geneva, Switzerland

Driven by beam dynamic considerations the Compact Linear Collider (CLIC) is expected to require extremely tight tolerances on most beam parameters. An important milestone was reached in 2011 with the completion of the CLIC conceptual design report. In this context the requirements for CLIC beam instrumentation has been reviewed and studied in detail for the whole accelerator complex with the aim of demonstrating feasibility. A preliminary choice has been made for every CLIC instrument, serving as a baseline scenario for the next phase of the project which will concentrate on the detailed design, engineering and test of CLIC devices. Whenever possible existing solutions have been studied, focusing on any improvements necessary to meet the CLIC performance criteria. When no such devices exists, or if cost considerations come into play, new technologies have been under study. Several prototypes are already well advanced and are currently under test. This paper presents an overview of CLIC beam instrumentation, the possible reach of their performance and an outlook on future developments.