A magnetically enhanced 3-electrode wireless micro-geiger counter

This paper explores a 3-electrode micromachined Geiger counter utilizing a high impedance (floating) electrode to control discharge energy, and its impact on sensitivity and response time. Permanent magnets in a sandwich configuration are used to enhance RF transmission from micro-discharges. Initially, weak (field-emission) leakage current charges the floating electrode capacitor (C_Pap1.1 pF) to a high voltage through the charging gap (between floating electrode and anode). When beta radiation initiates a micro-discharge in the sensing gap (between floating electrode and cathode), C_P dissipates through the low impedance path, lowering the voltage and quickly quenching the discharge. Permanent magnets, positioned perpendicular to the discharge path, increase the efficiency of electron-ion collisions and enhance the consequent RF transmission. Experiments conducted in a neon/air ambient with ⁹⁰Sr (0.1 muCi) showed a 10times-100times SNR improvement for the 3-electrode design over a similar 2-electrode design that does not utilize the floating electrode. Results also showed a significant increase in high frequency components in the presence of a magnetic field.