IPAC2013 - List of Authors (Hofmann, T.)

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.

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.