We report the measurement of very short, high-brightness bunches of electrons produced in a photocathode rf gun with no magnetic compression. The electron beam bunch length and the charge distribution along the bunch were measured by passing the energy chirped the electron beam through a momentum selection slit while varying the phase of the rf linac. The bunch compression as a function of rf gun phase and electric field at the cathode were investigated. The shortest measured bunch is 370+/-100 fs (at 95% of the charge) with 2.5X10(8) electrons (170 A peak current); the normalized rms emittance of this beam was measured to be 0.5 pi mm mrad and the energy spread is 0.15%.
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机译：我们报告了在没有磁性压缩的光电阴极射频枪中产生的非常短的高亮度电子束的测量结果。电子束的长度和沿束的电荷分布是通过使chi声的电子束通过动量选择狭缝同时改变直线加速器的相位来测量的。研究了束压缩与射频枪相和阴极电场的关系。测量的最短束为370 +/- 100 fs（在电荷的95％时），带有2.5X10（8）个电子（峰值电流为170 A）;经测量，该光束的归一化均方根发射率为0.5 pi mm mrad，能量散布为0.15％。
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