High resolution beam monitoring with optical transition radiation at 3 MeV electron energy

In the framework of the plasma beat wave accelerator experiment at Ecole Polytechnique, high precision position and focussing monitoring of a 3 MeV electron beam is needed. A device is proposed that uses backward optical transition radiation (OTR) from a tilted metal foil held into the beam. For an electron energy of 3 MeV, OTR is emitted within a large solid angle (typical apex angle about 400) around the direction of specular reflection. The design requirements are a high resolution of the imaging optics (/spl ap/10 /spl mu/m), a high sensitivity (/spl ap/ 10 /spl mu/A beam current, not focussed), robustness, and low cost. A prototype has been constructed and successfully tested. A similar device will be used for adjusting a laser focal spot on an electron focal spot, and for monitoring the beam on entry and exit of a gas vessel.<
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