IPAC2013 - List of Authors (Raich, U.)

Paper	Title	Page
MOPME075	Laser Based Stripping System for Measurement of the Transverse Emittance of H⁻ Beams at the CERN LINAC4	652
	T. Hofmann, E. Bravin, U. Raich, F. Roncarolo CERN, Geneva, Switzerland B. Cheymol ESS, Lund, Sweden
	Funding: LA3NET is funded by the European Commission under Grant Agreement Number GA-ITN-2011-289191 The new LINAC4 at CERN will accelerate H⁻ particles to 160 MeV and allow high brightness proton beam transfers to the Proton Synchrotron Booster, via a charge-exchange injection scheme. This paper describes the conceptual design of a laser system proposed for transverse profile and emittance measurements based on photon detachment of electrons from the H⁻ ions. The binding energy of the outer electron is only 0.75 eV and can easily be stripped with a laser beam. Measuring the electron signal as function of the laser position allows the transverse beam profile to be reconstructed. A downstream dipole can also be used to separate the laser neutralized H⁰ atoms from the main H⁻ beam. By imaging these H⁰ atoms as a function of laser position the transverse emittance can be reconstructed in the same way as in traditional slit-and-grid systems. By properly dimensioning the laser power and spot size, this method results in negligible beam losses and is therefore non-destructive. In addition, the absence of material intercepting the H⁻ beam allows the measurement of a full power H⁻ beam. This paper will focus on the general design and integration of both the laser and H⁰ detector systems.

THPWO082	Commissioning of the Linac4 RFQ at the 3 MeV Test Stand	3951
	C. Rossi, L. Arnaudon, G. Bellodi, J.C. Broere, O. Brunner, A.M. Lombardi, J. Marques Balula, P. Martinez Yanez, J. Noirjean, C. Pasquino, U. Raich, F. Roncarolo, M. Vretenar CERN, Geneva, Switzerland M. Desmons, A. France, O. Piquet CEA/IRFU, Gif-sur-Yvette, France
	Linac4, the future 160MeV H⁻ injector to the CERN Proton Synchrotron Booster, is presently under construction at CERN as a first step of the planned upgrade of the LHC injectors. The low energy section of LINAC4, consisting of an ion source, a 352.2 MHz Radio Frequency Quadrupole (RFQ) and a chopper line is being commissioned in a dedicated test stand before installation in its final position in the tunnel. The RFQ is designed to accelerate a 45 keV, 70 mA, H⁻ beam to 3 MeV, with an efficiency of 95% while preserving the transverse emittance. The RFQ, a four-vane structure 3 m in length, has been designed in collaboration with CEA/IRFU and it has been built at the CERN workshop. The precise fabrication has allowed to achieve a field flatness of 1%. The completion of the accelerating structure in September 2012 was followed by a complete series of bead-pull measurements and by high-power conditioning to the nominal power of 0.39 MW corresponding to a voltage of 78 kV across the 3 meters. Measurements with beam are foreseen during the first half of 2013. This paper reports the results of the low-power and high power RF commissioning as well as the status of beam measurements.

Paper

Title

Page

Laser Based Stripping System for Measurement of the Transverse Emittance of H⁻ Beams at the CERN LINAC4

652

T. Hofmann, E. Bravin, U. Raich, F. Roncarolo
CERN, Geneva, Switzerland
B. Cheymol
ESS, Lund, Sweden

Funding: LA3NET is funded by the European Commission under Grant Agreement Number GA-ITN-2011-289191
The new LINAC4 at CERN will accelerate H⁻ particles to 160 MeV and allow high brightness proton beam transfers to the Proton Synchrotron Booster, via a charge-exchange injection scheme. This paper describes the conceptual design of a laser system proposed for transverse profile and emittance measurements based on photon detachment of electrons from the H⁻ ions. The binding energy of the outer electron is only 0.75 eV and can easily be stripped with a laser beam. Measuring the electron signal as function of the laser position allows the transverse beam profile to be reconstructed. A downstream dipole can also be used to separate the laser neutralized H⁰ atoms from the main H⁻ beam. By imaging these H⁰ atoms as a function of laser position the transverse emittance can be reconstructed in the same way as in traditional slit-and-grid systems. By properly dimensioning the laser power and spot size, this method results in negligible beam losses and is therefore non-destructive. In addition, the absence of material intercepting the H⁻ beam allows the measurement of a full power H⁻ beam. This paper will focus on the general design and integration of both the laser and H⁰ detector systems.

THPWO082

Commissioning of the Linac4 RFQ at the 3 MeV Test Stand

3951

C. Rossi, L. Arnaudon, G. Bellodi, J.C. Broere, O. Brunner, A.M. Lombardi, J. Marques Balula, P. Martinez Yanez, J. Noirjean, C. Pasquino, U. Raich, F. Roncarolo, M. Vretenar
CERN, Geneva, Switzerland
M. Desmons, A. France, O. Piquet
CEA/IRFU, Gif-sur-Yvette, France

Linac4, the future 160MeV H⁻ injector to the CERN Proton Synchrotron Booster, is presently under construction at CERN as a first step of the planned upgrade of the LHC injectors. The low energy section of LINAC4, consisting of an ion source, a 352.2 MHz Radio Frequency Quadrupole (RFQ) and a chopper line is being commissioned in a dedicated test stand before installation in its final position in the tunnel. The RFQ is designed to accelerate a 45 keV, 70 mA, H⁻ beam to 3 MeV, with an efficiency of 95% while preserving the transverse emittance. The RFQ, a four-vane structure 3 m in length, has been designed in collaboration with CEA/IRFU and it has been built at the CERN workshop. The precise fabrication has allowed to achieve a field flatness of 1%. The completion of the accelerating structure in September 2012 was followed by a complete series of bead-pull measurements and by high-power conditioning to the nominal power of 0.39 MW corresponding to a voltage of 78 kV across the 3 meters. Measurements with beam are foreseen during the first half of 2013. This paper reports the results of the low-power and high power RF commissioning as well as the status of beam measurements.