In a Cherenkov detector, the refractive index of the conventional radiator sets a fundamental limit to the momentum coverage and sensitivity, for particle identification. For example for particles above 10 GeV/c, RICH detectors use large gas radiators. There is a dearth of materials to cover the full 1-10 GeV/c range. A new mechanism based on constructive interference of resonance transition radiation from photonic crystals is proposed to overcome this fundamental limit.
Photonic crystals can be designed from transparent dielectric materials to have the desired effective refractive index. They can produce forward and backward effective Cherenkov radiation in the optical and UV wavelengths. The typical overall thickness is a few millimetres.
Simulations based on FDTD (Finite Difference Time Domain) technique have shown that they can be configured for particle identification in different momentum ranges. However, they could potentially have chromatic error coming from the periodic structure. R&D to verify the performance using prototypes have started.
The results of simulations and potential for photonic crystals for particle identification are presented. The strategies to reduce the effect of the Chromatic error and to optimize the yield are discussed. The prospects for prototype testing are also presented.