Final answer:
Deadtime is the interval after a detection event when a Geiger-Müller counter is unresponsive to additional radiation, typically lasting from microseconds to milliseconds.
Step-by-step explanation:
The term deadtime refers to the period after a detection event during which a detector, like a Geiger-Müller counter, is unable to record another event. In the context of a Geiger-Müller counter, the deadtime is usually in the microseconds to milliseconds range. This is the time required for the detector to 'reset' itself after recording the passage of ionizing radiation. During the deadtime, any additional radiation that might occur is not counted, which can lead to inaccuracies in high radiation fields.