Dielectric laser acceleration draws upon nano-fabrication techniques to build photonic structures for high gradient electron acceleration. At the small spatial scales characteristic of these structures conventional accelerator techniques become ineffective at stabilizing the beam dynamics. Instead we propose a scheme to stabilize the motion by directly modulating the drive laser, in analogy to a radio-frequency-quadrupole. Here we present a design for a programmable `lattice being built at UCLAs Pegasus laboratory. The accelerator accepts an unmodulated 3.5 MeV electron beam and then bunches and accelerates the beam by 1.5 MeV over a distance of 2 cm.
Experimental measurements of beam halo diffusion dynamics with collimator scans are reviewed. The concept of halo control with a hollow electron beam collimator, its demonstration at the Tevatron, and its possible applications at the LHC are discussed.
Studies of the electron beam dynamics for the 4GLS design are presented. 4GLS will provide three different electron bunch trains to a variety of user synchrotron sources. The 1 kHz XUV-FEL and 100 mA High Average Current branches share a common 540 MeV linac, whilst the 13 MHz IR-FEL must be well-synchronised to them. An overview of the injector designs, electron transport, and energy recovery is given, including ongoing studies of coherent synchrotron radiation, beam break-up and wakefields. This work is being pursued for the forthcoming Technical Design Report due in 2008.
Precise coherent control of the individual electronic spins associated with atom-like impurities in the solid state is essential for applications in quantum information processing and quantum metrology. We demonstrate all-optical initialization, fast coherent manipulation, and readout of the electronic spin of the negatively charged nitrogen-vacancy (NV$^-$) center in diamond at T$sim$7K. We then present the observation of a novel double-dark resonance in the spectroscopy of an individual NV center. These techniques open the door for new applications ranging from robust manipulation of spin states using geometric quantum gates to quantum sensing and information processing.
A basic introduction to transverse and longitudinal beam dynamics as well as the most relevant beam loss mechanisms in circular machines will be presented in this lecture. This lecture is intended for physicists and engineers with little or no knowledge of this subject.
Beam halo is an important factor in any high intensity accelerator. It can cause difficulties in the control of the beam, emittance growth, particle loss and even damage to the accelerator. It is therefore essential to understand the mechanisms of halo formation and its dynamics in order to control and minimize its effects. Experimental measurement of the halo distribution is an important tool for such studies. In this paper, we present a new adaptive masking method that we have developed to image beam halo, which uses a digital micro-mirror-array device (DMD). This method has been thoroughly investigated in the laboratory using laser and white light sources, and with real beams produced by the University of Maryland Electron Ring (UMER). A high dynamic range ~10(5) has been demonstrated with this new method and recent studies indicate that this number can be exceeded for more intense beams by at least an order of magnitude. The method is flexible, easy to setup and can be used at any accelerator or light source. We present the results of our measurements of the performance of the method and images of beam halos produced under various experimental conditions.