| 摘要 |
<p>PURPOSE:To control the simultaneous counting caused by coincidence accidental or due to scattered light to a low level by memorizing only coincidence of specific detector pairs corresponding to a relative angle of rotation between the radiation source and detector pairs. CONSTITUTION:When a coincidence from a group of detectors 51 is detected with a coincidence circuit 52, an address of the detector pair involved is inputted into a data collection circuit 55 on the static side through a rotary photocoupler 54 and a coordinate value is read out of a memory 57 at a given point (t) with respect to specific pair of detectors 2 and 3 for handling immediate coincidence corresponding to the relative angle of rotation between the detector pair and the radiation source 5 rotating on an orbit 1 with the radius R. A circuit 55 counts the coordinate value of the detector pair at the point corresponding to the point (t) based on angles of the radiation source 5 and a detector support to the static base line 9 from a zebra-scale 53, an angle encoder 56 and the like and compares the results with the coordinate value read from the memory 57. When the results of the comparison are below the specified value, the detector pair involved is determined to be the specific detector pair. Thus, the addition is performed only for the immediate counting and none of the coincidence accidental or due to scattered light is picked up thereby preventing effect of noise data.</p> |
