| 摘要 |
PURPOSE:To improve counting rate characteristics by generating a timing signal in response to incidence of radiation having energy close to a specified energy- window, thereby reducing useless processing time. CONSTITUTION:Respective outputs of plural number of photoelectric transducers connected to a scintillator 22 are all added, and their addition signal is discriminated from a noise level by a discriminator 42. The addition signal is further sent to a discriminator 43, and it is discriminated that the signal exceeds a detection level close to a specified energy-window. Besides, when outputs are generated together from the discriminators 42, 43, a timing signal is generated. Then, an energy discriminating and position calculating circuit 31 begins to operate in response to the timing signal to count unblank signals for each position signal. Thus, the rate of processing events on which it becomes clear that they do not enter the energy-window, is reduced, and thereby useless processing time, unnecessary dead time are reduced to improve counting-rate characteristics.
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