In the FACET plasma-wakefield acceleration experiment a dense 23 GeV electron beam will interact with lithium and cesium plasmas, leading to plasma ion-channel formation. The interaction between the electron beam and the plasma sheath-electrons may lead to a fast growing electron hose instability. By using optics dispersion knobs to induce a controlled z-x tilt along the beam entering the plasma, we investigate the transverse behavior of the beam in the plasma as function of the tilt. We seek to quantify limits on the instability in order to further explore potential limitations on future plasma wakefield accelerators due to the electron hose instability. The FACET plasma-wakefield experiment at SLAC will study beam driven plasma wakefield acceleration. A dense 23 GeV electron beam will interact with lithium or cesium plasma, leading to plasma ion-channel formation. The interaction between the electron beam and the plasma sheath-electrons drives the electron hose instability, as first studied by Whittum. While Ref. [2] indicates the possibility of a large instability growth rate for typical beam and plasma parameters, other studies including have shown that several physical effects may mitigate the hosing growth rate substantially. So far there has been no quantitative benchmarking of experimentally observed hosing in …

Several linac driven X-ray Free Electron Lasers (XFELs) are being developed to provide high brightness photon beams with very short, tunable wavelengths. In this paper, three XFEL configurations are proposed that achieve LCLS-like performance using X-band linac drivers. These linacs are more versatile, efficient and compact than ones using S-band or C-band rf technology. For each of the designs, the overall accelerator layout and the shaping of the bunch longitudinal phase space are described briefly. During the last 40 years, the photon wavelengths from linac driven FELs have been pushed shorter by increasing the electron beam energy and adopting shorter period undulators. Recently, the wavelengths have reached the X-ray range, with FLASH (Free-Electron Laser in Hamburg) and LCLS (Linac Coherent Light Source) successfully providing users with soft and hard X-rays, respectively. FLASH uses a 1.2 GeV L-band (1.3 GHz) superconducting linac driver and can deliver 10-70 fs FWHM long photon pulses in a wavelength range of 44 nm to 4.1 nm. LCLS uses the last third of the SLAC 3 km S-band (2.856 GHz) normal-conducting linac to produce 3.5 GeV to 15 GeV bunches to generate soft and hard X-rays with good spatial coherence at wavelengths from 2.2 nm to …

SLAC expertise in designing and operating high current storage rings and the availability of the 2.2-km PEP-II tunnel present an opportunity for building a next generation light source - PEP-X - that would replace the SPEAR3 storage ring in the future. The PEP-X 'baseline' design, with 164 pm-rad emittance at 4.5 GeV beam energy and a current of 1.5 A, was completed in 2010. As a next step, a so-called 'ultimate' PEP-X lattice, reducing the emittance to 11 pm-rad at zero current, has been designed. This emittance approaches the diffraction limited photon emittance for multi-keV photons, providing near maximum photon brightness and high coherence. It is achieved by using 7-bend achromat cells in the ring arcs and a 90-m damping wiggler in one of the 6 long straight sections. Details of the lattice design, dynamic aperture, and calculations of the intra-beam scattering effect and Touschek lifetime at a nominal 0.2 A current are presented. Accelerator-based light sources are in high demand for many experimental applications. The availability of the 2.2-km PEP-II tunnel at SLAC presents an opportunity for building a next generation light source - PEP-X - that would replace the existing SPEAR3 light source in the future. The PEP-X …

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The rapid developments in the field of laser-driven particle acceleration hold the prospect of intense, highly relativistic electron bunches that are only a few fs long. The determination of the temporal profile of such bunches presents new challenges. The use of a radiative process such as Smith-Purcell radiation (SPR), is particularly promising in this respect. In this technique the beam is made to radiate a small amount of e/m radiation and the temporal profile is reconstructed from the measured spectral distribution of the radiation. We summarise the advantages of SPR and present the design parameters and preliminary results of the experiments at the FACET facility at SLAC. We also discuss a new approach to the problem of the recovery of the 'missing phase', which is essential for the accurate reconstruction of the temporal bunch profile.

There are relatively few reports in the literature focusing on negative laboratory leaders. Most of the reports focus exclusively on the simpler positive laboratory leader that is more commonly encountered in high voltage engineering [Gorin et al., 1976; Les Renardieres Group, 1977; Gallimberti, 1979; Domens et al., 1994; Bazelyan and Raizer 1998]. The physics of the long, negative leader and its positive counterpart are similar; the two differ primarily in their extension mechanisms [Bazelyan and Raizer, 1998]. Long negative sparks extend primarily by an intermittent process termed a 'step' that requires the development of secondary leader channels separated in space from the primary leader channel. Long positive sparks typically extend continuously, although, under proper conditions, their extension can be temporarily halted and begun again, and this is sometimes viewed as a stepping process. However, it is emphasized that the nature of positive leader stepping is not like that of negative leader stepping. There are several key observational studies of the propagation of long, negative-polarity laboratory sparks in air that have aided in the understanding of the stepping mechanisms exhibited by such sparks [e.g., Gorin et al., 1976; Les Renardieres Group, 1981; Ortega et al., 1994; Reess et al., 1995; Bazelyan …

The National Museum of the Pacific War presents an oral interview with William L. Bonning. Bonning had finished high school in 1941 and was grinding gears at Ford Motor Company in Detroit when he was drafted into the Army in January 1943. After a few failed attempts at joining the paratroopers, Bonning finally managed to pass the height requirement by stuffing matchbooks in his socks. He joined the paratroopers at Fort Benning, Georgia, in June, 1944. Bonning speaks of his experiences while training in Texas and Louisiana. He was in B Company, 504th Parachute Infantry Regiment, 82nd Airborne Division. He made it to France just in time to be moved to Belgium and join the fighting at the Battle of the Bulge. He shares many anecdotes about his time spent in combat and mentions many of his comrades by name.

The National Museum of the Pacific War presents an oral interview with William L. Bonning. Bonning had finished high school in 1941 and was grinding gears at Ford Motor Company in Detroit when he was drafted into the Army in January 1943. After a few failed attempts at joining the paratroopers, Bonning finally managed to pass the height requirement by stuffing matchbooks in his socks. He joined the paratroopers at Fort Benning, Georgia, in June, 1944. Bonning speaks of his experiences while training in Texas and Louisiana. He was in B Company, 504th Parachute Infantry Regiment, 82nd Airborne Division. He made it to France just in time to be moved to Belgium and join the fighting at the Battle of the Bulge. He shares many anecdotes about his time spent in combat and mentions many of his comrades by name.

A lattice for the PEP-X ultimate storage ring light source, having 11 pm-rad natural emittance at a beam energy of 4.5 GeV at zero current, using 90 m of damping wiggler and fitting into the existing 2.2-km PEP-II tunnel, has been recently designed. Such a low emittance lattice requires very strong sextupoles for chromaticity correction, which in turn introduce strong non-linear field effects that limit the beam dynamic aperture. In order to maximize the dynamic aperture we choose the cell phases to cancel the third and fourth order geometric resonances in each 8-cell arc. Four families of chromatic sextupoles and six families of geometric (or harmonic) sextupoles are added to correct the chromatic and amplitude-dependent tunes. To find the best settings of the ten sextupole families, we use a Multi-Objective Genetic Optimizer employing elegant to optimize the beam lifetime and dynamic aperture simultaneously. Then we evaluate dynamic aperture reduction caused by magnetic field multipole errors, magnet fabrication errors and misalignments. A sufficient dynamic aperture is obtained for injection, as well as workable beam lifetime.

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FACET (Facility for Advanced Accelerator and Experimental Tests) is a new User Facility at SLAC National Accelerator Laboratory. Its high power electron and positron beams make it a unique facility, ideal for beam-driven Plasma Wakefield Acceleration studies. The first 2 km of the SLAC linac produce 23 GeV, 3.2 nC electron and positron beams with short bunch lengths of 20 {mu}m. A final focusing system can produce beam spots 10 {mu}m wide. User-aided Commissioning took place in summer 2011 and FACET will formally come online in early 2012. We present the User Facility, the current features, planned upgrades and the opportunities for further experiments. Accelerators are our primary tool for discovering the fundamental laws to the universe. Each new frontier we probe requires a new, more powerful method. Accelerators are therefore increasing in size and cost. The future of this field requires new accelerating techniques that can reach the high energies required over shorter distances. New concepts for high gradient acceleration include utilizing the wakes in plasma and dielectric and metallic structures. FACET was built to provide a test bed for novel accelerating concepts with its high charge and highly compressed beams. As a test facility unlike any other, it …

Samples have been prepared from a 9975 lower fiberboard subassembly fabricated from softwood fiberboard. Physical, mechanical and thermal properties have been measured following varying periods of conditioning in each of several environments. These tests have been conducted in the same manner as previous testing on cane fiberboard samples. Overall, similar aging trends are observed for softwood and cane fiberboard samples, with a few differences. There is no clear trend thus far to indicate one material ages in a manner significantly different from the other material. Some softwood fiberboard properties degrade faster in some environments, while cane fiberboard degrades faster with regards to other properties and environments. Given the limited aging time accumulated to date in the elevated humidity environments, it is recommended that aging and testing of softwood fiberboard continue for another year. Post-conditioning data have been measured on samples from a single softwood fiberboard assembly, and baseline data are also available from a limited number of vendor-provided samples. This provides minimal information on the possible sample-to-sample variation exhibited by softwood fiberboard. Data to date are generally consistent with the range seen in cane fiberboard, but some portions of the data trends are skewed toward the lower end of that …

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The success of this proposal will open new areas of Chemistry with antimatter: (1) new chemical dynamics; (2) exclusive production of parent ions by energy-tuning the positrons; (3) formation of antimatter compounds; (4) nano- and microscopic imaging of molecules, cells, and tumors (5) multi-positron systems and their thermodynamics and chemical kinetics. Also with o-Ps and p-Ps physics including speculations of dark mater (PAMELA & ATIC reported excesses in the e{sup +}e{sup -} cosmic rays).

We propose a novel method to characterize the temporal duration and shape of femtosecond x-ray pulses in a free-electron laser (FEL) by measuring the time-resolved electron-beam energy loss and energy spread induced by the FEL process, with a transverse radio-frequency deflector located after the undulator. Its merits are simplicity, high resolution, wide diagnostic range, and non-invasive to user operation. When the system is applied to the Linac Coherent Light Source, the first hard x-ray free-electron laser in the world, it can provide single-shot measurements on the electron beam and x-ray pulses with a resolution on the order of 1-2 femtoseconds rms.

The measurement of ultra-short electron bunches on the femtosecond time scale constitutes a very challenging problem. In X-ray free-electron laser facilities such as the Linac Coherent Light Source (LCLS), generation of sub-ten femtosecond X-ray pulses is possible, and some efforts have been put into both ultra-short electron and X-ray beam diagnostics. Here we propose a single-shot method using a transverse rf deflector (X-band) after the undulator to reconstruct both the electron bunch and X-ray temporal profiles. Simulation studies show that about 1 fs (rms) time resolution may be achievable in the LCLS and is applicable to a wide range of FEL wavelengths and pulse lengths. The jitter, resolution and other related issues will be discussed. The successful operation of the Linac Coherent Light Source (LCLS), with its capability of generating free-electron laser (FEL) X-ray pulses from a few femtoseconds (fs) up to a few hundred fs, opens up vast opportunities for studying atoms and molecules on this unprecedented ultrashort time scale. However, tremendous challenges remain in the measurement and control of these ultrashort pulses with femtosecond precision, for both the electron beam (e-beam) and the X-ray pulses. For ultrashort e-beam bunch length measurements, a standard method has been established at …

The CEHMM algae to biodiesel project is a research and development endeavor investigating renewable fuels and a host of high-value co-products from the propagation, harvesting, and extraction of oil from a salt/brine water algae in open raceway ponds. Use of algae as renewable fuel feedstock complementary to petroleum diesel has great potential to make fuels and a host of valuable co-products, thereby reducing American dependence on foreign oil, sequestering carbon, and providing attractive multi-market returns for potential investors. This project is a green energy project thereby supporting the national agenda of a clean and renewable source of energy and will not compete with traditional food crops.

At the end of RHIC's 2009 operation a dedicated run for the PP2PP experiment (part of the STAR experiment) took place from Jun 29 to Jul 06 2009. Polarized protons were accelerated to 100 GeV using ramp-file pp100-90pp2pp with a {beta}* = 22 m in IR6. Since only transverse polarization was required no rotator ramp was in use. The PP2PP experiment consists mainly of two Roman Pot detectors (one horizontal and one vertical) on either side of IR6 in the outgoing-beam arms between the Q3 and Q4 magnets. The yellow pots are in sector 5, the blue ones in sector 6. Roman Pot type detectors are installed inside the beampipe causing an accelerator safety concern. To address this concern there is a limit to the allowable total beam current in the machine while Roman Pots are enabled to move closer to the beam. This limit was set to a motion limit of 5 mm from the center of the beampipe and 50 {center_dot} 10{sup 11} beam current per ring. In order to reduce the background in the detectors, beams were scraped using the RHIC collimator system prior to moving the pots closer. This was typically repeated several times throughout a …

The SLAC 3km linear electron accelerator has been reconfigured to provide a beam of electrons to the new Facility for Advanced Accelerator Experimental Tests (FACET) while simultaneously providing an electron beam to the Linac Coherent Light Source (LCLS). On June 23, 2011, the first electron beam was transported through this new facility. Commissioning of FACET is in progress. On June 23, 2011, an electron beam was successfully transported through the new FACET system to a dump in Sector 20 in the linac tunnel. This was achieved while the last third of the linac, operating from the same control room, but with a separate injector system, was providing an electron beam to the Linac Coherent Light Source (LCLS), demonstrating that concurrent operation of the two facilities is practical. With the initial checkout of the new transport line essentially complete, attention is now turning toward compressing the electron bunches longitudinally and focusing them transversely to support a variety of accelerator science experiments.

Coherent diffraction imaging of complex molecules such as proteins requires a large number (e.g., {approx} 10{sup 13}/pulse) of hard X-ray photons within a time scale of {approx} 10 fs or less. This corresponds to a peak power of {approx} 1 TW, much larger than that currently generated by LCLS or other proposed X-ray free electron lasers (FELs). We study the feasibility of producing such pulses using a LCLS-like, low charge electron beam, as will be possible in the LCLS-II upgrade project, employing a configuration beginning with a SASE amplifier, followed by a 'self-seeding' crystal monochromator, and finishing with a long tapered undulator. Our results suggest that TW-level output power at 8.3 keV is possible from a total undulator system length around 200 m. In addition power levels larger than 100 GW are generated at the third harmonic. We present a tapering strategy that extends the original 'resonant particle' formalism by optimizing the transport lattice to maximize optical guiding and enhance net energy extraction. We discuss the transverse and longitudinal coherence properties of the output radiation pulse and the expected output pulse energy sensitivity, both to taper errors and to power fluctuations on the monochromatized SASE seed.

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