A a scientist who is not a physicist and you might hear that we physicists are an arrogant bunch. And to a layperson, scientists in general often seem arrogant. No, we shrug, we’re not really arrogant, we are just very objective and thus usually right! We are certainly a group with admirable strength in our convictions. Could there be a problem with welltempered arrogance? I have worked in a nu...

Hard x-ray Free electron lasers (FEL) are being built or proposed at many accelerator laboratories as it supports wide range of applications in many aspects. Most of the hard x-ray FEL design is similar with the SLAC Linac Coherent Light Source (LCLS), which features a two (or multiple) stage bunch compression. For the first stage of the bunch compression, usually the beam is accelerated in a l...

It has been demonstrated experimentally that laser plasma accelerators can produce multi-100 MeV electron bunches with a few percent energy spread, and from these electrons, multi-MeV quasi-monoenergetic photons have based on Compton up-scattering counter-propagating laser. This offers the potential of high-quality, narrow-bandwidth, compact, photon source broad application. The bandwidth resul...

Various methods to generate ultrashort electron bunches for the ultrafast science evolved from the simple configuration of two-plate vacuum diodes to advanced technologies such as nanotips or photocathodes excited by femtosecond lasers. In a diode either in vacuum or of solid-state, the transit-time limit originating from finite electron mobility has caused spatiotemporal bunch-collapse in ultr...

A new method of monitoring the luminosity has been developed at CESR. The method involves shaking one bunch at a speciic frequency and observing the resulting oscillations of the corresponding opposing bunch. In initial tests, measurements with 1% accuracy have been obtained in 1 second. Measurements of diierent bunches in a train shows bunch to bunch diierences with the optimum luminosity cond...

We propose a versatile THz source named FLUTE (Ferninfrarot LinacUnd Test-Experiment) based on a 30 50 MeV S-band linac with bunch compressor, that aims at not only producing high field THz pulses but also at serving as a test facility to study accelerator physics issues. This source is an important step towards the planned ultra-broadband THz to mid infrared user facility TBONE. Special emphas...

A bunch-by-bunch beam diagnostic system which consists of a high speed light shutter and an optical beam detector has been developed. Since the open/close time of the shutter is comparable to a bunch spacing of 2 ns, it is capable of picking out the light pulses from a particular bunch in a bunch train. The selected pulses can be analyzed with conventional optical beam diagnostic methods in ord...

We describe a proposed all-dielectric laser-driven undulator for the generation of coherent short wavelengths and explore the required electron beam parameters for its operation. The key concept for this laser-driven undulator is its ability to provide phase synchronicity between the deflection force from the laser and the electron beam for a distance that is much greater than the laser wavelen...

The new type of solutions of the London equation for type-II superconductors is obtained to describe the ring-shaped (toroidal) Abrikosov vortices. The specific feature of these solutions is the self-consistent localization of both the supercurrent and the magnetic field, enabling one to construct compact magnetic structures inside a superconductor. The torus vortex contraction caused by the vo...

Transverse bunch-by-bunch feedback systems for damping coupled-bunch instabilities in the KEKB rings have been working well since the early stages of the commissioning of the rings. Beam diagnostic systems that are the part of the bunch feedback systems, such as bunch current monitors, betatron-tune measurements systems, and bunch oscillation recorders, have been playing important roles in the ...