Proposal of a threshold type Cherenkov PET detector without pulse height measurements

We have developed the new production methods of silica aerogel with the refractive indices between 1.15 and 1.25. Since the velocity of the photoelectric electron from the 511keV photon is 0.866c and the maximum velocity of the Compton electron is 0.8c, only photoelectric electrons occurs the Cherenkov light inside the radiator with n ~ 1.2. We are constructing the simple prototype PET detectors using these silica aerogels. Since there are no efficiency for the Compton events, the pulse height measurements are not need. The data acquisition system becomes very simple.