Abstract
A high sensitive detection system for heavy ions of low energy was described. In order to improve the conversion efficiency from positive or negative heavy ions, to electrons at the conversion dynode of the electron multiplier, the whole assembly of detection sysytem (electron multiplier, d. c. amplifier, high voltage power supply for the electron multiplier and power supply for the d. c. amplifier and A-D converter) were isolated from the ground and were kept at -10kV potential for the positive ion detection and +10kV for the negative ion detection. The d. c. signal from the d. c. amplifier was converted to 12-bits digital signal by the A-D converter and was sent to the ground side by light-emitting-diodes (LED). It was received by photo-transistors and converted back to a d. c. signal by a D-A converter. The conversion cycle of the A-D converter was 8 μsec. With this detection sysytem, the high sensitivity for negative heavy ions was obtained.
