Zero Ion Backflow electron multiplier operating in noble gases

We present a novel concept for the suppression of secondary ions in gaseous detectors. The Zero Ion Backflow electron multiplier operates in a noble gas atmosphere and effectively suppresses the ion back flow to the level of primary ionization, totally blocking the secondary ions produced in the multiplier. This detector is composed by a proportional scintillation region, established between two highly transparent meshes, followed by a Gaseous Photomultiplier (GPM). The ionization electrons drift towards the scintillation region, where a proportional electroluminescence signal is produced, without the production of any secondary ionization. A fraction of the emitted VUV scintillation is collected by the photocathode of the GPM and the photoelectron signal is amplified in the GPM through electron avalanche processes. The positive ions of the avalanches developed in the GPM are totally blocked by the mesh that separates the scintillation region and the GPM, resulting in full ion back-flow suppression of secondary ions into the drift/conversion region of the detector. The full suppression capability is independent of the GPM gain. The Zero Ion Backflow electron multiplier is an alternative to readout the ionization signals of Time Projection Chambers in which the accumulation of secondary ions in the sensitive region of the detector has the potential to affect its performance.