Performance improvement of a discrete dynode electron multiplication system through the optimization of secondary electron emitter and the adoption of double-grid dynode structure

The discrete dynode electron multiplication system (DD-EMS) is the core part of commonly used photomultiplier tubes and electron multipliers, and it has a great influence on the signal amplification capability of these devices. In this work, the sputtering time of Mg target during the deposition of the surface MgO layer of the MgO/ (MgO-Au)/Au multilayer film as the secondary electron emitter was optimized, and the strategy of double-grid structures applied at the 7th and 8th dynodes was proposed with the intention of improving the gain and stability of nine-stage DD-EMS under electron bombardment to satisfy the requirements of detecting the single photon or single charged particle. The investigation results show that the DD-EMS fabricated by using the MgO/(MgO-Au)/ Au film with a Mg target's sputtering time of 3600 s has the highest maximal gain of 1.22 x 106 and the lowest gain attenuation rate of 15.7%/mC under electron bombardment. In addition, the DD-EMS with the double-grid structure has a higher maximal gain of 1.62 x 106 and a lower gain attenuation rate of 11.6%/mC under continuous electron bombardment, which are 32.8% increased and 17.7% reduced respectively in comparison with that of the single-grid structure.