| 摘要 |
PURPOSE:To set automatically a window width so that a Compton edge is not contained, by detecting a valley between the Compton edge and a peak. CONSTITUTION:A command is given to a controlling circuit 1 so that an energy window is set automatically, and a peak value A is derived automatically by an auto peak circuit 2. This peak value A becomes a value B whose energy is little lower than the peak value A by an operating circuit 3. This value is converted to an analog voltage by a D/A converting circuit 5, and voltages of B+V and B-V are obtained by an adder 6 and a subtracter 7. This voltage is compared with an energy signal Z by comparators 8, 9, and in case of Z>B, the value B decreases, and in case of Z<B, the value B increases. As a result, B is settled down to a value in which count values of the upper side and the lower side of the value B are equal in a specified range. The value B of this time becomes a value C of a valley between a peak P and a Compton edge Q. Subsequently, by an end signal EOP outputted from the circuit 1, the value A and C are obtained as an output D from an adder 16 through analog multipliers 14, 15. That is to say, the value C of the valley and the output D become the lower limit value and the upper limit value of the window width, respectively, and the energy window is set. |
