Laser-wire

Introduction

The performance of linear collider depends strongly on the control of the transverse particle beam size along the complete machine, for example to verify beam optics and to measure the transverse beam emittance. Some of the expected beam sizes are in the range between 500 nm and 10 µm, where conventional wire scanners are at the limit of their resolution. To provide a non-invasive measurement we suggest to use a laser beam to probe the electron beam. The central idea is to use Compton scattering between electrons in the bunch and photons in the laser beam

Installed laser wire projects

After a first round of ATF extraction line laser wire, we plan to upgrade the laser wire to operate within the ATF2, ATF2 laser wire project. Similarly after a test installation at PETRA2, we have commissioned a turn key laser wire system for PETRA3. We are also developing fast laser scanners. There is a program of lens characterisation and performance study here. A utility has been developed to perform analysis of laser profiler systems profilerAnalysis.

Papers, conference proceedings, theses

• Lawrence Deacon : A Micron-Scale Laser-Based Beam Profile Monitor for the International Linear Collider, April 2009.
• Michael Price : Laser-Wire Studies for PETRA and the International Linear Collider, November 2007.
• Stephen Malton : Laser Interactions with High Brightness Electron Beams, February 2007
• John Carter : Particle Physics and Beam-Line Studies for the Electron-Positron International Linear Collider, October 2006
• Freddy Poirier : Beam Diagnostic Laser-wire and Fast Luminosity Spectrum Measurement at the International Linear Collider, July 2005

Publications

• Beam emittance measurement with laser wire scanners in the International Linear Collider beam delivery system Phys. Rev. Special Topics - Accel. Beams, 10, 112801 (2007), Issue 11
• A two-dimensional laser-wire scanner for electron accelerators, A. Bosco et al, Nucl. Instrum. Meth. A 592, 2008, issue 3, 162-170
• A large aperture electro-optic deflector, Appl. Phys. Lett. 94, 211104 (2009)

Public resources

• Accelerator tracking code in python
• Optical simulation codes

References

• Parameters of Compton x-ray beams: Total yield and pulse duration. Phys. Rev. Special Topics - Accelerators and Beams 8, 030703 (2005) Article
• Measurement of an electron beam size with a laser wire beam profile monitor. Phys. Rev. Special Topics - Accelerators and Beams 4, 022801 (2001) Article