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How do becquerels and curies measure the radioactivity of a sample?
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radiation measurement
Figure 1: (A) A simple equivalent circuit for the development of a voltage pulse at the output of a detector. R represents the resistance and C the capacitance of the circuit; V(t) is the time (t)-dependent voltage produced. (B) A representative current pulse due to the interaction of a single quantum in the detector. The total charge Q is obtained by integrating the area of the current, i(t), over the collection time, tc. (C) The resulting voltage pulse that is developed across the circuit of (A) for the case of a long circuit time constant. The amplitude (Vmax) of the pulse is equal to the charge Q divided by the capacitance C.
Becquerels and curies are units used to measure the activity of a radioactive sample, which refers to the number of unstable atomic nuclei that decay per second. This activity is determined by using radiation detectors and electronic circuits to count the particles or photons emitted during a specific time interval.1
- Becquerel (Bq): This is the official unit of radioactivity in the International System of Units (SI). One becquerel is defined as exactly one atomic disintegration per second. Because it represents a very small amount of radioactivity, it is often used for precise measurements, such as in household smoke detectors.213
- Curie (Ci): This is an older standard unit that was replaced by the becquerel in 1975. One curie is defined as disintegrations per second, which is approximately the activity of one gram of radium.23
In summary, the two units are related by the conversion .21