Difference: BarrelDirc (r3 vs. r2)

the DIRC provides

• a positive kaon identification
• a destinction of gammas and relativistic charged particles entering the EMC behind him

• Cherenkov Detector
• determination of the mass of the particle by combining his velocity information with momentum information from the tracking detectors

* Polar angle vs. momentum distribution of the kaons in radiative decays of resonances in formation experiments like J/psi -> K+K- gamma for the search of glue-balls.:

• Polar angle vs. momentum distribution of the kaons in radiative decays of resonances in formation experiments like J/psi -> K+K- gamma for the search of glue-balls (Ref. TPR):
  

• the barrel DIRC covers the solid angle of 22 to 140 degrees
• the lower momentum threshold for kaons which produce Cherenkov light is for an envisaged refractive index of n=1.47 as low as 460 MeV/c (for single photon producton -- for photon numbers bigger than 4 it is more than 200 MeV/c higher)

-- CarstenSchwarz - 18 Apr 2006