Synthesis and characterisation of fluorinated epitaxial films of BaFeO2_{2}F: Tailoring magnetic anisotropy: Via a lowering of tetragonal distortion

In this article, we report on the synthesis and characterisation of fluorinated epitaxial films of BaFeO$_{2}$F via low-temperature fluorination of thin films of BaFeO$_{2.5+d}$ grown by pulsed laser deposition. Diffraction measurements show that fluoride incorporation only results in a contraction of the film perpendicular to the film surface, where clamping by the substrate is prohibitive for strong in-plane changes. The fluorinated films were found to be homogenous regarding the fluorine content over the whole film thickness, and can be considered as single crystal equivalents to the bulk phase BaFeO$_{2}$F. Surprisingly, fluorination resulted in the change of the tetragonal distortion to a nearly cubic symmetry, which results in a lowering of anisotropic orientation of the magnetic moments of the antiferromagnetically ordered compound, confirmed by Mössbauer spectroscopy and magnetic studies

Real-time transverse-emittance and phase-space monitor

A real-time multislit [1] transverse-emittance monitor has been developed for diagnosing the space-charge-dominated beam in the 10MeV injection line of the FEL at Thomas Jefferson National Accelerator Facility (formerly CEBAF). It gives emittance, Twiss parameters, and phase-space contours (without any symmetry assumptions) at the update rate of 1Hz. It reduces measurement noise in real-time, and incorporates a special algorithm for constructing the phase-space matrix, which yields more accurate results by sweeping the beam across the slits. In this paper we will discuss issues relevant to the software design and implementation. Experimental results obtained from a 250keV photocathode gun will also be presented and compared with other methods and with PARMELA simulations

A High-Average-Power Free Electron Laser for Microfabrication and Surface Applications

CEBAF has developed a comprehensive conceptual design of an industrial user facility based on a kilowatt ultraviolet (UV) (160-1000 mm) and infrared (IR) (2-25 micron) free electron laser (FEL) driven by a recirculating, energy recovering 200 MeV superconducting radio frequency (SRF) accelerator. FEL users, CEBAF's partners in the Lase Processing Consortium, including AT&T, DuPont, IBM, Northrop Grumman, 3M, and Xerox, are developing applications such as metal, ceramic, and electronic material micro-fabrication and polymer and metal surface processing, with the overall effort leading to later scale-up to industrial systems at 50-100 kW. Representative applications are described. The proposed high-average-power FEL overcomes limitations of conventional laser sources in available power, cost-effectiveness, tunability, and pulse structure

Aggression, anxiety and vocalizations in animals: GABA A and 5-HT anxiolytics

A continuing challenge for preclinical research on anxiolytic drugs is to capture the affective dimension that characterizes anxiety and aggression, either in their adaptive forms or when they become of clinical concern. Experimental protocols for the preclinical study of anxiolytic drugs typically involve the suppression of conditioned or unconditioned social and exploratory behavior (e.g., punished drinking or social interactions) and demonstrate the reversal of this behavioral suppression by drugs acting on the benzodiazepine-GABA A complex. Less frequently, aversive events engender increases in conditioned or unconditioned behavior that are reversed by anxiolytic drugs (e.g., fear-potentiated startle). More recently, putative anxiolytics which target 5-HT receptor subtypes produced effects in these traditional protocols that often are not systematic and robust. We propose ethological studies of vocal expressions in rodents and primates during social confrontations, separation from social companions, or exposure to aversive environmental events as promising sources of information on the affective features of behavior. This approach focusses on vocal and other display behavior with clear functional validity and homology. Drugs with anxiolytic effects that act on the benzodiazepine-GABA A receptor complex and on 5-HT 1A receptors systematically and potently alter specific vocalizations in rodents and primates in a pharmacologically reversible manner; the specificity of these effects on vocalizations is evident due to the effectiveness of low doses that do not compromise other physiological and behavioral processes. Antagonists at the benzodiazepine receptor reverse the effects of full agonists on vocalizations, particularly when these occur in threatening, startling and distressing contexts. With the development of antagonists at 5-HT receptor subtypes, it can be anticipated that similar receptor-specificity can be established for the effects of 5-HT anxiolytics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46351/1/213_2005_Article_BF02245590.pd

Automated startup of the CEBAF 45 MeV injector

In order to improve the speed and reproducibility of restoring the beam in the Continuous Electron Beam Accelerator Facility (CEBAF) 45 MeV injector after a full or partial shutdown of the accelerator, a program has been written using the Tcl/Tk scripting language to automate most of the required steps. The procedure is separated into four main parts. The first part performs preliminary checks that verify that the hardware is set correctly and then turns on the main interlocked systems including high power magnets and RF. The second step turns on the gun high voltage. The final steps turn on the beam and verify that the beam quality is satisfactory by measuring the transmission, orbit, transverse beam size, and bunch length. Minor corrections for phasing are also performed in the program. In order to identify inefficiencies in the startup, each is timed and parameter changes are logged so that system drifts can be tracked. This paper describes the software implementation, the logic to achieve a successful startup, and efficiency results

Sc-substituted Nasicon solid electrolyte for an all-solid-state NaxCoO2/Nasicon/Na sodium model battery with stable electrochemical performance

All-solid-state sodium batteries are attractive due to the abundance of sodium and advantageous for safe battery operation by avoiding flammable organics and liquids and suppressed dendrite formation. Currently, the lack of a chemically stable sodium solid electrolyte with high ion conductivity at room temperature is one of the challenges for future development of sodium batteries. Herein, we present a NaxCoO2/Nasicon/Na thin-film model sodium solid-state battery using a Sc-substituted Nasicon solid electrolyte with a high ionic conductivity of 4 × 10⁻³ S cm⁻¹. The battery shows a high specific capacity of 150 mAh g⁻¹ at room-temperature and discharge rates of up to 6C. Excellent chemical stability of this solid electrolyte at high voltages of up to 4.2 V increases the accessible sodium (de)intercalation range and battery capacity. Direct extraction of the interface resistances between the electrode materials of the thin-film model cell using electrochemical impedance spectroscopy gives a unique opportunity of correlation the electrochemical performance with properties of electrode materials and their interfaces