DETECTOR VOLTAGERadiation DetectorsSummaryThe alpha curve is higher than the beta curve from Region I to part of Region IV due to thelarger number of ion pairs produced by the initial reaction of the incident radiation. Detectorvoltage principles are summarized below.Gas Amplification Region SummaryRecombination RegionThe voltage is such a low value that recombination takes place before most of thenegative ions are collected by the electrode.Ionization RegionThe voltage is sufficient to ensure all ion pairs produced by the incident radiation arecollected.No gas amplification takes place.Proportional RegionThe voltage is sufficient to ensure all ion pairs produced by the incident radiation arecollected.Amount of gas amplification is proportional to the applied voltage.Limited Proportional RegionAs voltage increases, additional processes occur leading to increased ionizations.Since positive ions remain near their point of origin, further avalanches are impossible.Geiger-Müller RegionThe ion pair production is independent of the radiation, causing the initial ionization.The field strength is so great that the discharge continues to spread until amplificationcannot occur, due to a dense positive ion sheath surrounding the central wire.Continuous Discharge RegionThe applied voltage is so high that, once ionization takes place, there is a continuousdischarge of electricity.IC-06 Page 18 Rev. 0
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