59359588
Quasicrystalline Beam Formation in RF Photoinjectors
The recent observation of coherent optical transition radiation at the LCLS has raised serious questions concerning the present model of beam dynamics in RF photoinjectors. We present here an analysis of what we term quasicrystalline beam formation. In this scenario, the low longitudinal temperature, in combination with strong acceleration and temporal rearrangement due to bending, allows the longitudinal beam dimension to become more regular, on the microscopic scale of optical wavelengths, than expected from equilibrium statistical properties. This beam distribution then may then display a strong degree of coherence in its optical transition radiation output. We discuss further experimental investigations of this phenomenon.
55077257
THE ALPHA FERRITE-LOADED COAXIAL RESONATOR CAVITY
The Advanced Electron Photon Facility (ALPHA) [1] is a joint collaboration between the Indiana University Center for Exploration of Energy and Matter and the Crane Naval Surface Warfare Center. The ALPHA storage ring will serve as a debuncher in single pass mode of operation. With a set of two gradient damping wigglers, the storage ring can also accumulate to achieve high charge density beams. In this report, we present the design, fabrication, and testing of the 15MHz ferrite-loaded quarter-wave rf coaxial resonator cavity that will be utilized in the ALPHA storage ring. Topics pertaining to beam lifetime, radiation damping, ferrite-loaded transmission lines, and key cavity parameters will be discussed.
41591864
A substellar common proper-motion companion to the Pleiad H II 1348
We announce the identification of a proper-motion companion to the star H II 1348, a K5 V member of the Pleiades open cluster. The existence of a faint point source 1farcs1 away from H II 1348 was previously known from adaptive optics imaging by Bouvier et al. However, because of a high likelihood of background star contamination and in the absence of follow-up astrometry, Bouvier et al. tentatively concluded that the candidate companion was not physically associated with H II 1348. We establish the proper-motion association of the pair from adaptive optics imaging with the Palomar 5 m telescope. Adaptive optics spectroscopy with the integral field spectrograph OSIRIS on the Keck 10 m telescope reveals that the companion has a spectral type of M8 ± 1. According to substellar evolution models, the M8 spectral type resides within the substellar mass regime at the age of the Pleiades. The primary itself is a known double-lined spectroscopic binary, which makes the resolved companion, H II 1348B, the least massive and widest component of this hierarchical triple system and the first substellar companion to a stellar primary in the Pleiades.