Cherenkov Diffraction Radiation Emissions from Single Electrons and Positrons on a Fused Silica Radiator

Beam diagnostics are crucial for smooth accelerator operations. Many techniques rely on instrumentation in which the beam properties are significantly affected by the measurement. Novel approaches aim to use Cherenkov Diffraction Radiation (ChDR) for non-invasive diagnostics. Unlike regular Cherenkov Radiation, the charged particles do not have to move inside of the medium, but it is sufficient for them to move in its vicinity as long as they are faster than the speed of light in the medium. Changes to the beam properties due to ChDR measurements are consequently negligible. To examine ChDR emission under different conditions, we placed a fused silica radiator in the DESY II Test Beam. We observed increases in ChDR intensity for electron and positron momenta between <math display="inline" id="d1e1710" altimg="si47.svg"><mrow><mtext>1</mtext><mspace width="0.16667em"/><mtext>GeV</mtext><mspace width="0.16667em"/><mtext>c</mtext><msup><mrow/><mrow><mi>−1</mi></mrow></msup></mrow></math> and <math display="inline" id="d1e1727" altimg="si38.svg"><mrow><mtext>5</mtext><mspace width="0.16667em"/><mtext>GeV</mtext><mspace width="0.16667em"/><mtext>c</mtext><msup><mrow/><mrow><mi>−1</mi></mrow></msup></mrow></math>. Additionally, we found a larger photon yield for electrons than positrons for increasing particle momenta. However, the significance of these measurements is strongly limited by the accuracy of the conversion from the measured signal to absolute photon numbers. The results suggest a need for further research into the ChDR generation by electrons and positrons and may find application in the design of future beam diagnostic devices.