  We present measurement and analyses of longitudinal timing jitter of Beijing
Electron Positron Collider (BEPCII) linear accelerator electron gun. We
simulated longitudinal jitter effect of the gun using PARMELA about beam
performance including beam profile, average energy, energy spread, longitudinal
phase of reference particle and XY emittance. The maximum percentage difference
of the beam parameters are calculated to be; 100%, 13.27%, 42.24%, 7.79% and
65.01%, 86.81%, respectively due to which the bunching efficiency is reduced to
54%. The simulation results are in agreement with test and are helpful to
optimize the beam parameters by tuning the trigger timing of the gun during the
bunching process.
