Feasibility of Diffraction Radiation for a Non-invasive Diagnostics of the SLAC Electron Beam

The development of the non-invasive bunch size diagnostics based on the diffraction radiation is now in progress in frame of TPU-KEK-SLAC collaboration. The experimental test of a transverse beam size measurement was performed successful on the KEK-ATF extracted electron beam. However many difficulties emerge if we going from the one GeV electron energy to the several tenth GeV electron beams. The extremely high Lorenz-factor value gives rise to the some problems, such as large contribution of a radiation from an accelerator construction elements in submillimeter wavelength region, extremely pre-wave zone effect even in the optical range, exceeding of the electron beam divergence over the diffraction radiation cone, and so on. More over, the sensitivity of the method based on the optical diffraction radiation from flat slit target decrease catastrophic when an electron energy increase up to several tenth GeV. We suggest the new method based on the phase shift on the slit target, consisting on the two semi-planes which are turned at a some angle one to other (crossed target technique) and present here the results of experimental test of this technique. Also we discuss the origins of indicated difficulties and suggest the ways of these problems solution

DEVELOPMENT OF A GAS-SHEET BEAM PROFILE MONITOR

Abstract For fast and non-destructive beam profile detection in ion synchrotrons, a monitor using gas-sheet target is developed. The pressure of the target is 2.5 x 10 -7 Torr, the thickness 1.3 mm, and the width 100 mm. On a performance test using an extracted 8 MeV proton beam from NIRS-Cyclotron, a beam profile was successfully measured

The Possibility of Noninvasive Micron High Energy Electron Beam Size Measurement Using Diffraction Radiation

A new method based on diffraction radiation emitted by charged particles moving through a slit between two flat rectangular plates inclined with respect to each other around the axis perpendicular to the slit has been suggested. The theoretical model for calculating the ODR radiation from such targets (including focusing by cylindrical lens) is presented. It is shown that the sensitivity of this method does not depend on the Lorenzfactor directly. The target with the ''dis-phased'' angle 6.2 milliradians and the slit width 425 microns was manufactured for experimental test. Some preliminary experimental results are presented