LINAC2014 - List of Authors (Raich, U.)

Paper	Title	Page
MOPP025	Longitudinal Beam Profile Measurements in Linac4 Commissioning	108
	G. Bellodi, V.A. Dimov, J.-B. Lallement, A.M. Lombardi, U. Raich, F. Roncarolo, F. Zocca CERN, Geneva, Switzerland M. Yarmohammadi Satri IPM, Tehran, Iran
	Linac4, the future 160 MeV H⁻ injector to the CERN Proton Synchrotron Booster, is presently under construction at CERN as a central step of the planned upgrade of the LHC injectors. The Linac front-end, composed of a 45 keV ion source, a Low Energy Beam Transport (LEBT), a 352.2 MHz Radio Frequency Quadrupole (RFQ) and a Medium Energy Beam Transport (MEBT) housing a beam chopper, has been installed and commissioned. Precise measurements of the longitudinalμbunch profiles of ion beams were possible with the help of a Bunch Shape Monitor (BSM) developed at INR Moscow. These were crucial for the successful commissioning of the three RF buncher cavities mounted along the MEBT and well complemented with higher precision the information provided in parallel by spectrometer measurements.

TUPP034	Commissioning of the CERN LINAC4 Wire Scanner, Wire Grid and Slit-Grid Monitors at 3 and 12 MeV	502
	F. Roncarolo, U. Raich, F. Zocca CERN, Geneva, Switzerland
	The CERN LINAC4 has been commissioned up to 12 MeV. The H⁻ beam transverse profile distributions were measured by both wire grids and wire scanners. A slit-grid system located on a temporary diagnostics bench was used to characterize the transverse emittance during the two different stages of commissioning: at the exit of the RFQ (3 MeV) and DTL1 (12 MeV). The wire signal is a balance between the negative charge deposited by the stripped electrons from the H⁻ and the charge lost due to secondary emission. Optimal settings were found for the repelling plates used to suppress secondary emission, which were confirmed by electromagnetic simulations. In addition, suppression of the secondary emission due to the beam space charge was observed. The benefit of changing the wire scanner geometry in order to minimize the cross-talk between horizontal and vertical wires and the observation of thermionic emission on carbon wires are also discussed.

TUPP035	Transverse Profile and Emittance Measurements With a Laser Stripping System During the CERN LINAC4 Commissioning at 3 and 12 MeV	506
	F. Roncarolo, E. Bravin, T. Hofmann, U. Raich, F. Zocca CERN, Geneva, Switzerland G.E. Boorman, A. Bosco, S.M. Gibson, K.O. Kruchinin Royal Holloway, University of London, Surrey, United Kingdom C. Gabor STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom J.K. Pozimski Imperial College of Science and Technology, Department of Physics, London, United Kingdom
	The CERN LINAC4 beam commissioning at 3 and 12 MeV was completed in 2014. A novel system for measuring the transverse beam profile and emittance, based on low power laser stripping and H⁰ detection using a diamond detector, was successfully tested at these two energies. The measurement results agree with the operational slit-grid method within a few percent in terms of both transverse profile and emittance. After describing the general system setup, this remarkable achievement is discussed in detail together with the present limitations, which will be addressed in order to design a laser based emittance monitor for the LINAC4 top energy of 160 MeV.

TUPP038	Transverse Beam Profile Measurements in the Linac4 Medium Energy Beam Transport	516
SUPG029	use link to see paper's listing under its alternate paper code
	M. Yarmohammadi Satri, G. Bellodi, V.A. Dimov, J.-B. Lallement, A.M. Lombardi, U. Raich, F. Roncarolo, F. Zocca CERN, Geneva, Switzerland
	Linac4 is a 160 MeV H⁻ linear accelerator presently under construction at CERN. It will replace the present 50 MeV proton Linac2 as injector of the proton accelerator complex as part of a project to increase the LHC luminosity. The Linac4 front-end, composed of a 45 keV ion source, a Low Energy Beam Transport (LEBT), a 352.2 MHz Radio Frequency Quadrupole (RFQ) which accelerates the beam to 3 MeV and a Medium Energy Beam Transport (MEBT) housing a beam chopper, has been commissioned in the Linac4 tunnel. The MEBT is composed of three buncher cavities and 11 quadrupole magnets to match the beam from the RFQ to the next accelerating structure (DTL) and it includes two wire scanners for beam profile measurement. In this paper we present the results of the profile measurements and we compare them with emittance measurements taken with a temporary slit-and-grid emittance measurement device located after the MEBT line.

Paper

Title

Page

Longitudinal Beam Profile Measurements in Linac4 Commissioning

108

G. Bellodi, V.A. Dimov, J.-B. Lallement, A.M. Lombardi, U. Raich, F. Roncarolo, F. Zocca
CERN, Geneva, Switzerland
M. Yarmohammadi Satri
IPM, Tehran, Iran

Linac4, the future 160 MeV H⁻ injector to the CERN Proton Synchrotron Booster, is presently under construction at CERN as a central step of the planned upgrade of the LHC injectors. The Linac front-end, composed of a 45 keV ion source, a Low Energy Beam Transport (LEBT), a 352.2 MHz Radio Frequency Quadrupole (RFQ) and a Medium Energy Beam Transport (MEBT) housing a beam chopper, has been installed and commissioned. Precise measurements of the longitudinalμbunch profiles of ion beams were possible with the help of a Bunch Shape Monitor (BSM) developed at INR Moscow. These were crucial for the successful commissioning of the three RF buncher cavities mounted along the MEBT and well complemented with higher precision the information provided in parallel by spectrometer measurements.

TUPP034

Commissioning of the CERN LINAC4 Wire Scanner, Wire Grid and Slit-Grid Monitors at 3 and 12 MeV

502

F. Roncarolo, U. Raich, F. Zocca
CERN, Geneva, Switzerland

The CERN LINAC4 has been commissioned up to 12 MeV. The H⁻ beam transverse profile distributions were measured by both wire grids and wire scanners. A slit-grid system located on a temporary diagnostics bench was used to characterize the transverse emittance during the two different stages of commissioning: at the exit of the RFQ (3 MeV) and DTL1 (12 MeV). The wire signal is a balance between the negative charge deposited by the stripped electrons from the H⁻ and the charge lost due to secondary emission. Optimal settings were found for the repelling plates used to suppress secondary emission, which were confirmed by electromagnetic simulations. In addition, suppression of the secondary emission due to the beam space charge was observed. The benefit of changing the wire scanner geometry in order to minimize the cross-talk between horizontal and vertical wires and the observation of thermionic emission on carbon wires are also discussed.

TUPP035

Transverse Profile and Emittance Measurements With a Laser Stripping System During the CERN LINAC4 Commissioning at 3 and 12 MeV

506

F. Roncarolo, E. Bravin, T. Hofmann, U. Raich, F. Zocca
CERN, Geneva, Switzerland
G.E. Boorman, A. Bosco, S.M. Gibson, K.O. Kruchinin
Royal Holloway, University of London, Surrey, United Kingdom
C. Gabor
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
J.K. Pozimski
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

The CERN LINAC4 beam commissioning at 3 and 12 MeV was completed in 2014. A novel system for measuring the transverse beam profile and emittance, based on low power laser stripping and H⁰ detection using a diamond detector, was successfully tested at these two energies. The measurement results agree with the operational slit-grid method within a few percent in terms of both transverse profile and emittance. After describing the general system setup, this remarkable achievement is discussed in detail together with the present limitations, which will be addressed in order to design a laser based emittance monitor for the LINAC4 top energy of 160 MeV.

TUPP038

Transverse Beam Profile Measurements in the Linac4 Medium Energy Beam Transport

516

SUPG029

use link to see paper's listing under its alternate paper code

M. Yarmohammadi Satri, G. Bellodi, V.A. Dimov, J.-B. Lallement, A.M. Lombardi, U. Raich, F. Roncarolo, F. Zocca
CERN, Geneva, Switzerland

Linac4 is a 160 MeV H⁻ linear accelerator presently under construction at CERN. It will replace the present 50 MeV proton Linac2 as injector of the proton accelerator complex as part of a project to increase the LHC luminosity. The Linac4 front-end, composed of a 45 keV ion source, a Low Energy Beam Transport (LEBT), a 352.2 MHz Radio Frequency Quadrupole (RFQ) which accelerates the beam to 3 MeV and a Medium Energy Beam Transport (MEBT) housing a beam chopper, has been commissioned in the Linac4 tunnel. The MEBT is composed of three buncher cavities and 11 quadrupole magnets to match the beam from the RFQ to the next accelerating structure (DTL) and it includes two wire scanners for beam profile measurement. In this paper we present the results of the profile measurements and we compare them with emittance measurements taken with a temporary slit-and-grid emittance measurement device located after the MEBT line.