Dose rate meter
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Dose rate meters or dose rate meters are used in radiation protection to measure the dose rate . In contrast to the dosimeter , which shows the radiation dose accumulated over a period of time, a dose rate meter measures the current radiation dose per time (e.g. in µSv / h).
Executions
Dose rate measuring devices are available in versions for use in laboratories , but also more robust versions for emergency services such as fire brigade or police . Often such devices are also dose rate warning devices . Some operational devices are combinations of dose rate meter and dosimeter. Dose rate measuring devices can also be used temporarily (only for gamma-emitting contamination) as contamination detection devices.
A dose rate meter for self-construction is the Safecast device .
technology
Dose rate meters usually contain a Geiger-Müller counter tube as a radiation detector . The count rate is shown on an analog or digital display in units of the dose equivalent rate . A signal sounds when a set warning threshold is reached.
Additional probes / telescope dose rate meters
In order to burden the user of the device with the lowest possible dose, there are dose rate meters with telescopic probes . The probe, i.e. the detector, is then up to several meters away from the display device - and thus from the person operating it - at the tip of an extendable "telescopic rod". So z. B. the probe can be held in a doorway, while the person uses the shielding effect of the building wall. But the distance even without protective shielding significantly lowers the dose rate on the user's body. At a z. B. 4 meter long telescopic probe, the tip of which is 1 m from a radiation source, the operator is 5 m away from it. If the radiation source is small compared to this distance, the dose rate recorded by the operator is - in accordance with the law of the distance square - only 1/25 of that which would be recorded if he held the probe directly in his hand.
Some of these devices have a counter tube end window that can be covered with a protective cap to enable the detection of beta radiation . Depending on the manufacturer and the measuring range, several counter tubes are built into the probe.
In the fire brigade telescopic dose rate meter are connected to a measuring range of 0.5 mSv / h to 10 Sv / h usual. Gamma and X-rays can be measured, beta radiation can be partially detected.
Web links
- The Glossary radiation protection of the Jülich Research Center explained many terms round (etc. units dosimeter dose terms, alpha, beta, gamma radiation, radiation protection) to ionizing radiation.