Amplification and scintillation properties of oxygen-rich gas mixtures for optical-TPC applications

We studied electron amplification and light emission from avalanches in oxygen-containing gas mixtures. The mixtures investigated in this work included, among others, CO2 and N2O mixed with Triethylamine (TEA) or N2. Double-Step Parallel Gap (DSPG) multipliers and THick Gas Electron Multipliers (THGEM) were investigated. High light yields were measured from CO2 + N2 and CO2 + TEA, though with different emission spectra. We observed the characteristic wave-length emission of N2 and of TEA and used a polymer wave-length shifter to convert TEA UV-light into the visible spectrum. The results of these measurements indicate the applicability of optical recording of ionizing tracks in a TPC target-detector designed to study the cross-sections of the 16O(?, ?)12C reaction, a central problem in nuclear astrophysics.