The present work reports on Yttrium based photocathodes. A Yttrium (Y) thin film is deposited via pulsed laser deposition (PLD) on the copper (Cu) back flange of a radio frequency (rf) gun for photocathode application. Because of a lower work function with respect to Cu, Y photocathodes are particularly appealing for the possibility to illuminate them with visible laser pulses, with the advantage of a higher energy per pulse, paving the way to high repetition rate photoinjectors, driven by conventional laser sources. In addition, working at $\lambda \sim 400\mathrm{nm}$ the small energy difference between the Y work function (about 3 eV) and the laser photon energy reduces the contribution of the intrinsic emittance of the material. Photoelectrons, emitted by the thin film Y photocathode driven by the second harmonic of a Ti:Sapphire laser, have been characterized in terms of quantum efficiency and transverse emittance. Results have been compared with the theoretical ones obtained by the three-step model of Spicer for metallic photocathodes.

中文翻译：

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利用可见光辐射研究钇光电阴极的光发射

本工作报告了基于钇的光电阴极。钇（Y）薄膜通过脉冲激光沉积（PLD）沉积在射频（rf）枪的铜（Cu）后凸缘上，用于光电阴极应用。由于相对于Cu的功函数较低，Y光电阴极特别吸引人的可能性是用可见激光脉冲照亮它们，其优点是每个脉冲的能量更高，从而为常规激光驱动的高重复频率光电注入器铺平了道路资料来源。此外，在$\lambda 〜400\mathrm{纳米}$Y功函数（约3 eV）与激光光子能量之间的小能量差减小了材料固有发射的贡献。由Ti：Sapphire激光器的二次谐波驱动的薄膜Y光电阴极发出的光电子已经在量子效率和横向发射率方面进行了表征。将结果与Spicer的三步模型对金属光阴极的理论结果进行了比较。