During the last year we re-configured the ATA injector to accommodate field emission cathodes. The injector is now run as a diode machine with a 7 cm radius cathode, an A-K gap of 12.9 cm and a field stress of 190 kV/cm. The advantage of using field emission cathodes is we have increased the injector brightness by a factor of ten above the level we were able to reach using the low density plasma cathodes.

Clouds of electrons in the vacuum chambers of accelerators of positively charged particle beams present a serious limitation for operation of these machines at high currents. Because of the size of these accelerators, it is difficult to probe the low energy electrons clouds over substantial lengths of the beam pipe. We applied a novel technique to directly measure the electron cloud density via the phase shift induced in a TE wave which is independently excited and transmitted over a straight section of the accelerator. The modulation in the wave transmission which appears to increase in depth when the clearing solenoids are switched off, seem to be directly correlated to the electron cloud density in the section. Furthermore, we expect a larger phase shift of a wave transmitted through magnetic dipole field regionsif the transmitted wave couples with the gyration motion of the electrons. We have used this technique to measure the average electron cloud density (ECD) specifically for the first time in magnetic field regions of a new 4-dipole chicane in the positron ring of the PEP-II collider at SLAC. In this paper we present and discuss the measurements taken in the Low Energy Ring (LER) between 2006 and 2008.

Incoherent electron effects could seriously limit the beam lifetime in proton or ion storage rings, such as LHC, SPS, or RHIC, or blow up the vertical emittance of positron beams, e.g., at the B factories or in linear-collider damping rings. Different approaches to modeling these effects each have their own merits and drawbacks. We describe several simulation codes which simplify the descriptions of the beam-electron interaction and of the accelerator structure in various different ways, and present results for a toy model of the SPS. In addition, we present evidence that for positron beams the interplay of incoherent electron-cloud effects and synchrotron radiation can lead to a significant increase in vertical equilibrium emittance. The magnitude of a few incoherent e+e- scattering processes is also estimated. Options for future code development are reviewed.

I present a summary of topics relevant to the electron-cloud build-up and dissipation that were presented at the International Workshop on Electron-Cloud Effects 'ECLOUD 07' (Daegu, S. Korea, April 9-12, 2007). This summary is not meant to be a comprehensive review of the talks. Rather, I focus on those developments that I found, in my personal opinion, especially interesting. The contributions, all excellent, are posted in http://chep.knu.ac.kr/ecloud07/.

In a recent Letter [1], Bhimalapuram, Chakrabarty and Bagchi (BCB) study the phase transformation mechanism of the Lennard-Jones fluid and the non-conserved Ising model. They compute the free energy as a function of the size of the largest droplet of the stable phase. In apparent contradiction to classical nucleation theory (CNT), they find that in both systems the free energy develops a minimum at subcritical cluster sizes. In this Comment we argue that this minimum is specific to the chosen order parameter, and that the observed behavior is in fact consistent with CNT. CNT states that the free energy F(N) of a single cluster of size N is a concave function with a maximum at the critical nucleus size N{sub c}. BCB, on the other hand, calculate the probability distribution of N*, the size of the largest cluster in the system, and compute the free energy {beta}F*(N*) = -ln P(N*), where {beta} = 1/k{sub B}T. This order parameter does not measure the size of a single cluster. Instead, when sampling small values of N*, one measures the statistical weight of configurations in which all clusters are at most N* in size. Hence a free energy penalty is incurred when one …

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One of the areas of fundamental beam physics that have served as the rationale for recent research on UMER is the study of the generation and evolution of beam halos. Recent experiments and simulations have identified imperfections in the source geometry, particularly in the region near the emitter edge, as a significant potential source of halo particles. The edge-generated halo particles, both in the experiments and the simulations are found to pass through the center of the beam a short distance downstream of the anode plane. Understanding the detailed evolution of these particle orbits is therefore important to designing any aperture to remove the beam halo.

Described is a computer-based gamma ray spectrometer system using a germanium detector for rapid nondestructive measurement of isotopic and total plutonium concentrations in solutions at nuclear reprocessing plants. Isotopic concentrations have been measured with an accuracy of +-0.5%. Cell design, calibration techniques, and preliminary results are discussed. This system is being installed at the Tokai reprocessing plant in Japan.

These notes give an overview of some aspects of the quantum theory of light and its interaction with matter. A description is given of basic emission and absorption processes, as well as the theory of photodetection and optical coherence. Basic research in this area is increasingly relevant to areas of technological importance, including microlaser devices and the noise characteristics of semiconductor lasers.

A novel approach to providing high voltage (>10 MV), high current (>200 kA), short duration (20-40 ns), particle beam pulses is described. The approach uses 1 MV Metglas isolated cavities driven by water pulse lines. These are stacked in series by using a magnetically insulated cathode stalk. Results from modeling of the cavity and cores and from a full sized single-cavity experiment are discussed. Plans for a four-cavity experiment to prove the principle of voltage addition by stacking cavities on a magnetically insulated transmission line are also described. The single-cavity experiments produced a 1.1 MV, 30 ns FWHM, 12 ns rise time, 250 kA electron beam. The HELIA pulsed power system and cavities are described. Particle-in-cell (PIC) computer simulations of the four-cavity experiment and the four-cavity conceptual design are discussed. 13 references, 14 figures.

This article proposes a reconfigurable surface plasmon polariton (SPP) wave adapter designed by transformation optics, which can control the propagation of SPP waves on un-even surfaces.

This report gives the preliminary results on work done to find a scintillator that is compatible with high-bandwidth, long-distance fiber-optic transmission. The requirements for such a scintillator are: (1) emission in the near-IR; (2) linear output over 2 to 3 decades of input excitation; (3) time response < 2 ns; and (4) immunity to radiation damage. The behavior of single crystal cadmium sulfide (CdS) and cadmium selenide (CdSe) was examined under electron and laser excitation. Both crystals emit in the deep red, however, time response was found to be slower than 2 ns. Neither crystal exhibited good linearity over the entire range of input excitation.

Four unique deisgn features are described which make the Fast Flux Test Facility eminently suitable for irradiation test programs. These features are a fast flux level of 7 x 10/sup 15/ neutrons/cm/sup 2//sec, a 36-inch reference (breeder reactor) core height, test volumes suitable for testing of statistical quantities of materials, and the capability for direct (contact) or indirect (proximity) instrumentation of active core experiments.

As part of the Dual Axis Radiography Hydrotest Facility, Phase II (DARHT II) multipulse Bremsstrahlung target, we have been performing an investigation of (1) the possible adverse effects of backstreaming ion emission from the Bremsstrahlung converter target and (2) maintaining sufficient target density to ensure dose in latter pulses. Theory predictions show that the first effect would primarily be manifested in the static focusing system as a rapidly varying x-ray spot. From experiments performed on ETA-II, we have shown that the first effect is not strongly present when the beam initially interacts with the target. Electron beam pulses delivered to the target after formation of a plasma are strongly affected, however. Secondly, we have performed studies of the effect of the time varying target density on dose and seek to demonstrate various techniques for maintaining that density. Measurements are presented of the target density as a function of time and are compared with our hydrodynamic models.

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We explore the sonification of x-ray scattering data, which are two-dimensional arrays of intensity whose meaning is obscure and non-intuitive. Direct mapping of the experimental data into sound is found to produce timbral sonifications that, while sacrificing conventional aesthetic appeal, provide a rich auditory landscape for exploration. We discuss the optimization of sonification variables, and speculate on potential real-world applications. We have presented a case study of sonifying x-ray scattering data. Direct mapping of the two-dimensional intensity values of a scattering dataset into the two-dimensional matrix of a sonogram is a natural and information-preserving operation that creates rich sounds. Our work supports the notion that many problems in understanding rather abstract scientific datasets can be ameliorated by adding the auditory modality of sonification. We further emphasize that sonification need not be limited to time-series data: any data matrix is amenable. Timbral sonification is less obviously aesthetic, than tonal sonification, which generate melody, harmony, or rhythm. However these musical sonifications necessarily sacrifice information content for beauty. Timbral sonification is useful because the entire dataset is represented. Non-musicians can understand the data through the overall color of the sound; audio experts can extract more detailed insight by studying all the features of …

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These notes give an overview of some aspects of the quantum theory of light and its interaction with matter. A description is given of basic emission and absorption processes, as well as the theory of photodetection and optical coherence. Basic research in this area is increasingly relevant to areas of technological importance, including microlaser devices and the noise characteristics of semiconductor lasers.