| 摘要 |
PURPOSE:To reduce ion feedback and noise by installing an accelerating electrode on this side of the output terminal of a cylindrical secondary electron multiplier having an inner wall surface made of a secondary-electron-discharging semiconductive material and fixing a collector electrode on the end surface of the output terminal. CONSTITUTION:A secondary electron multiplier 11 is made by forming a semiconductive material having a secondary-electron-discharging ability into a cylindrical shape which is then curved into spiral form. A cone-like input electrode 12 is attached to the input terminal 11a of the multiplier 11. An accelerating electrode 13 to which acceleration voltage (EL) is applied is wound around a position which is located on this side of the output terminal 11b of the multiplier 11 and apart from it by a distance (d) of about 5mm.. Next, a collector electrode 14 is fixed to the end surface of the output terminal 11b. After that, a load resistance (RL) is connected between the electrode 14 and an earth, and voltage delivered from the resistance (RL) is amplified with a pre-amplifier 5. Owing to the above constitution, the generation of ion feedback and noise can be reduced, the structure can be simplified and the acceleration voltage can be decreased. A member provided between the electrodes 13 and 14 may consist of an insulating cylinder. |
