Detalle de: Secondary scintillation yield of xenon with sub-percent levels of CO2 additive for rare-event detection

Xe–CO 2 mixtures are important alternatives to pure xenon in Time Projection Chambers (TPC) based on secondary scintillation (electroluminescence) signal amplification with applications in the important field of rare event detection such as directional dark matter, double electron capture and double beta decay detection. The addition of CO 2 to pure xenon at the level of 0.05–0.1% can reduce significantly the scale of electron diffusion from 10 mm / m to 2.5 mm / m , with high impact on the discrimination efficiency of the events through pattern recognition of the topology of primary ionization trails. We have measured the electroluminescence (EL) yield of Xe–CO 2 mixtures, with sub-percent CO 2 concentrations. We demonstrate that the EL production is still high in these mixtures, 70% and 35% relative to that produced in pure xenon, for CO 2 concentrations around 0.05% and 0.1%, respectively. The contribution of the statistical fluctuations in EL production to the energy resolution increases with increasing CO 2 concentration, being smaller than the contribution of the Fano factor for concentrations below 0.1% CO 2 .