An RF pulse compressor is a device used to convert a long RF pulse to a short one with a much higher peak RF magnitude. SLED can be regarded as the earliest RF pulse compressor to be used in large-scale linear accelerators. It has been widely studied around the world and applied in the BEPC and BEPCⅡ linac for many years. During routine operation, error and jitter effects will deteriorate the performance of SLED, either on the output electromagnetic wave amplitude or phase. The error effects mainly include the frequency drift induced by cooling water temperature variation and the frequency/Q 0 /β unbalances between the two energy storage cavities caused by mechanical fabrication or microwave tuning. The jitter effects refer to the PSK switching phase and time jitters. In this paper, we re-derive the generalized formulae for the conventional SLED used in the BEPCⅡ linac, and the error and jitter effects on SLED performance are also investigated.
A study of spin dynamics based on simulations with the Polymorphic Tracking Code （PTC） is reported, exploring the dependence of the static polarization limit on various beam parameters and lattice settings for a practical RHIC lattice. It is shown that the behavior of the static polarization limit is dominantly affected by the vertical motion, while the effect of beam-beam interaction is small. In addition, the ＂nonresonant beam polarization＂ observed and studied in the lattice-independent model is also observed in this lattice-dependent model. Therefore, this simulation study gives insights of polarization evolution at fixed beam energies, that are not available in simple spin tracking.
Polarized positrons can be generated through the electron-positron pair creation from circularly polarized gamma-rays hitting a conversion target. Laser-Compton scattering is an efficient method to generate circularly polarized gamma-rays. Simulation studies on these two processes have been done with the Monte Carlo codes, CAIN and GEANT4. Using CAIN to simulate the Laser-Compton scattering process, the energy spectrum of the generated polarized photons could be obtained. GEANT4 was used to study the yield, energy spectrum and the mean polarization of the positrons emanating from the conversion target. To increase the yield of the generated positrons, an optimization study on the thickness of conversion target was also performed.
