Proposal of Cherenkov TOFPET with silica aerogel

Silica aerogel with the refractive index of around 1.2 has been developed. It is argued that a Cherenkov counters with using this silica aerogel could be applied as a new gamma detector of positron emission tomography. Since a Cherenkov photon is emitted in a radiator of n>1.156 for a 511 keV electron and that of n>125 for 341 keV one (compton edge of 511 keV gamma), only photoelectric effect could be detected. The time resolution of a Cherenkov counter is essentially more superior than that of a scintillation counter. The TOF measurement could determine the three dimensional coordinate of the annihilation position of the positron with sufficient resolution. The production method of silica aerogel with such refractive index is shown. The expected properties of this Cherenkov counter are discussed. A simple proof-of-principle experiment confirms the feasibility of the new PET detector.