Scintillation counter dead time

By adding the three above components, the resulting dead time of a scintillation counter is of the order of 1-5 fxs. This is much shorter than the dead time of gas-filled counters, which is of the order of tens to hundreds of microseconds. 

A typical dead time for a scintillation detector is 5 fis. For a gas counter, the corresponding number is 200 /ns. If a sample counted with a gas counter results in 8 percent loss of gross counts due to dead time, what is the corresponding loss in a scintillation counter that records the same gross counting rate ... 

The most widely used modern scintillation detector consists of a transparent crystal of sodium iodide that has been activated by the introduction of 0.2% thallium iodide. Often, the crystal is shaped as a cylinder that is 3 to 4 in. in each dimension one of the plane surfaces then faces the cathode of a photomultiplier tube. As the incoming radiation passes through the crystal, its energy is first lost to the scintillator, this energy is subsequently released in the form of photons of fluorescence radiation. Several thousand photons with a wavelength of about 400 nm are produced by each primary particle or photon over a period of about 0.25 ps, which is the dead time. The dead time of a scintillation counter is thus significantly smaller than the dead time of a gas-filled detector. 

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