Bias supply powers low power Geiger Mueller tube


Posted on Feb 5, 2014

Pulse size and width are independent of the pulse energy or other properties of the event. Geiger-Mueller tubes are less sensitive to non-gamma-ray radiation, and their dose-rate calibration accuracy is poor. They are widely used because they offer a good compromise in cost/performance/size for applications that require quick detection of a radiation field and a rough


Bias supply powers low power Geiger Mueller tube
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estimate of its level. One problem with Geiger-Mueller tubes is their high bias voltage, which is 350V to 900V depending on the tube design and the mixture of gases used. Ideally, a given tube is biased to operate in the center of its plateau,  a region of 100V to 150V in which the counting rate varies little with bias voltage (assuming a stable radiation field). The miniaturization of a portable radiation monitor is limited by the size of the tube, which defines sensitivity, and the amount of operating time between battery replacements or rechargings. Aside from the high-voltage supply, radiation-monitor circuitry is relatively simple: a pulse ratemeter with analog or digital readout (indicating the radiation dose rate), and a visual or audio indication of frequency for the radiation events striking the detector tube. Some systems include an integration function that indicates the total dosage since last reset. These circuits are easily designed in micropower versions that allow a longer period of operation between battery charges. The HV power supply, however, poses problems. A large portion of the system`s quiescent power consumption occurs in the resistive divider that sets the output-voltage sample. For absolute-minimum power consumption, you must use very high-resistance values for the top portion of the dividerway beyond the maximum 22M available in most standard resistor lines. High-valued resistors complicate the...




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