THE SCINTILLATION OF CF4 AND ITS RELEVANCE TO DETECTION SCIENCE

The scintillation properties of CF4 are presented in comparison with those of Xe and CH4. Alpha-particle induced photon emission was measured with vacuum phototubes and with a CsI-based gaseous photomultiplier. The latter method provides an absolute sensitivity of such devices to particle-induced W-photon background in CF4 and CH4 gaseous Cherenkov radiators. Integrated CF4 scintillation yields over the range of 150-220 nm are, on the average, 315+/-95 to 242+/-60 photons/MeV, in the respective pressure range of 0.063 to 0.75 atm, compared to CH4 which emits 0.06 +/- 0.01 photons/MeV at 1 atm. The total photon yield, integrated over the full emission spectrum of CF4 (150-500 nm), is of the order of 1200 photons/MeV X 4 pi. The primary scintillation photon yield of CF4 is about 16(+/-5)% of that of Xe. No proportional secondary scintillation was observed in CF4. The avalanche-induced photon yield was measured to be of the order of 0.3 photons per electron. The implications of this considerable photon emission, are discussed.