Direct Observation of Incoherent Cherenkov Diffraction Radiation in the Visible Range
R Kieffer1, L Bartnik2, M Bergamaschi1
1CERN, CH-1211 Geneva 23, Switzerland.
Physical Review Letters
|August 18, 2018
Summary
We observed incoherent Cherenkov radiation from a positron beam near a fused silica radiator. This finding has potential applications in non-invasive beam diagnostics for particle accelerators.
Area of Science:
- High-energy physics
- Accelerator physics
- Optics
Background:
- Cherenkov radiation is produced when charged particles travel faster than the phase velocity of light in a medium.
- Incoherent Cherenkov radiation is emitted over a broad spectrum and can be a source of detectable photons.
- Non-invasive beam diagnostics are crucial for monitoring and controlling particle beams in accelerators.
Purpose of the Study:
- To observe and characterize incoherent Cherenkov radiation emitted by a positron beam.
- To investigate the relationship between radiation intensity and beam proximity to a radiator surface.
- To assess the potential of this phenomenon for accelerator beam diagnostics.
Main Methods:
- A 5.3 GeV positron beam was circulated in the Cornell electron-positron storage ring.
- The beam passed near a specifically shaped fused silica radiator.
- A compact optical system with an intensified camera recorded Cherenkov photons, measuring 2D images, angular distribution, and polarization.
Main Results:
- Incoherent Cherenkov radiation was successfully observed.
- Measured light intensity agreed well with theoretical predictions as a function of beam-radiator distance.
- A light yield of 0.8×10^-3 photon/particle/turn was measured at 600 nm for a 1 mm impact parameter.
Conclusions:
- Incoherent Cherenkov radiation can be effectively generated and detected using a positron beam and a fused silica radiator.
- The observed radiation intensity correlates with theoretical models, validating the experimental approach.
- This method shows promise for developing non-invasive beam diagnostics in accelerators for various particle types.
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