We describe the performance of the Boolardy Engineering Test Array, the prototype for the Australian Square Kilometre Array Pathfinder telescope. Boolardy Engineering Test Array is the first aperture synthesis radio telescope to use phased array feed technology, giving it the ability to electronically form up to nine dual-polarisation beams. We report the methods developed for forming and measuring the beams, and the adaptations that have been made to the traditional calibration and imaging procedures in order to allow BETA to function as a multi-beam aperture synthesis telescope. We describe the commissioning of the instrument and present details of Boolardy Engineering Test Array’s performance: sensitivity, beam characteristics, polarimetric properties, and image quality. We summarise the astronomical science that it has produced and draw lessons from operating Boolardy Engineering Test Array that will be relevant to the commissioning and operation of the final Australian Square Kilometre Array Path telescope.

The IntCal09 and Marine09 radiocarbon calibration curves have been revised utilizing newly available and updated data sets from 14C measurements on tree rings, plant macrofossils, speleothems, corals, and foraminifera. The calibration curves were derived from the data using the random walk model (RWM) used to generate IntCal09 and Marine09, which has been revised to account for additional uncertainties and error structures. The new curves were ratified at the 21st International Radiocarbon conference in July 2012 and are available as Supplemental Material at www.radiocarbon.org. The database can be accessed at http://intcal.qub.ac.uk/intcal13/.

This paper describes the system architecture of a newly constructed radio telescope – the Boolardy engineering test array, which is a prototype of the Australian square kilometre array pathfinder telescope. Phased array feed technology is used to form multiple simultaneous beams per antenna, providing astronomers with unprecedented survey speed. The test array described here is a six-antenna interferometer, fitted with prototype signal processing hardware capable of forming at least nine dual-polarisation beams simultaneously, allowing several square degrees to be imaged in a single pointed observation. The main purpose of the test array is to develop beamforming and wide-field calibration methods for use with the full telescope, but it will also be capable of limited early science demonstrations.

Novel field emission (FE) devices are introduced employing lateral architecture. Ultrathin multiwalled carbon nanotube (MWCNT) sheet were utilized to fabricate the emitter. Effects of basic configuration of sheets, including the orientation of CNTs and sheet thickness were examined. The novel device achieved the threshold field (the electric field at which current density reach 1 mA/cm2) of 0.67 V/µm and enhancement factor larger than 20,000.

In order to make desirable surface layers by low pressure plasma spraying (LPPS), optimum operating conditions and plasma torch gun designs must be decided upon for understanding LPPS plasma and powder behavior. As the first step of this approach, LPPS plasmas without powders were measured by the Thomson scattering, the Michelson interferometry and a Pitot tube. These diagnostics revealed that LPPS plasma jets may be treated as supersonic neutral gas flows as the first approximation. In addition, the neutral particle temperature Tn and ion temperature Ti were found to be the same as the electron temperature Te, which is 1 eV at an oblique shock wave heating point and 0.2 eV at the sugsequent cooling point. LPPS plasmas and flows were modeled by a computer Simulation of a supersonic nozzle flow, 2nd yielded reasonable understanding of the thermodynamic and fluid-mechanical conditions.

Formation, growth and deposition of particles represent a critical part of several important industrial processes, such as production of carbon black, optical fibers, micro-electronic components, and metal and ceramic powders. Laser diagnostic techniques are utilized to develop a fundamental understanding of these processes.

Formation of carbonaceous soot particles has been studied in laminar, coannular, hydrocarbon diffusion flames. Laser extinction/scattering, laser scattering dissymmetry, and velocimetry measurements have been used to determine particle volume fraction, size, number density and velocity. From this set of data, particle formation and growth rates have been determined for different fuels and at different temperatures. Similar techniques have been used to study silica particle formation in an opposed jet diffusion flame, where silicon is introduced in the form of silane (SiH4) into the fuel stream (H2/Ar); the oxidant is an O2/Ar mixture. The advantage of this geometry is that, along the stagnation point streamline, the flow may be considered one-dimensional. This should allow the extension of the results of this study to practical CVD or MCVD processes for optical fibers. Laser diagnostic techniques are also being used to investigate metal powder atomization processes, and the effect of operating conditions on particle size distribution.

Oxide - carbon multilayer coatings were continuously applied to various fibers of nominal SiC composition. A liquid-phase coating system that allows application of the coatings in a controlled atmosphere at relatively rapid rates was employed. Sugar - ammonium hydroxide solutions were used for carbon coatings, and aqueous sols were used for the oxides. Carbon was also deposited simultaneously with alumina by chemical vapor deposition of a hydrocarbon in the coating furnace. The coatings were extensively characterized by optical microscopy and TEM. Problems with embrittlement by oxide coatings and poor adherence of oxide coatings on carbon, and some possible solutions to these problems, are discussed.

A method of preparing transmission electron microscopy (TEM) specimens of coated ceramic fibers has been developed that produces large areas containing many electron transparent fibers, due to the minimal preferential milling of the epoxy matrix. Multiple individual fibers or tows are impregnated with a high-temperature epoxy and contained to assure a high fiber-to-epoxy volume ratio. The samples are then sectioned and mechanically thinned either parallel or normal to the fiber axes using a wedge polisher on diamond lapping films to achieve a thickness of less than 5 μm. The thinned sample is then ion-milled to electron transparency in less than 30 min, giving representative specimens of the coating, fiber, and coating-fiber interface. This technique is also well suited to preparing extremely flat specimens for both light microscopy and scanning electron microscopy analysis of thin coatings.

We have modified a normal-incidence optical reflectance spectroscopy system to allow rapid switching between the measurement of sample reflectance and sample emission. The resulting optical system is capable of “smart” pyrometry, in which sample emissivity is measured rather than assumed. The emissivity measurement makes use of the principle of detailed balance, which states that for specular, opaque samples, the sum of the emissivity and reflectance at each wavelength is equal to 1. We present data based on multilayer III-V semiconductor structures grown by molecular beam epitaxy, but the optical system would function equally well in any growth or deposition system with optical access to the substrate. The “smart” pyrometry temperatures we measure typically differs from conventional pyrometry by 5 to 10°C, and occasionally as much as 20°C, for multilayer structures of AIGaAs and GaAs. We present details of the optical components and arrangement that minimize the effect of sample wobble and allow the system operator regular visual access to the sample. Calibration techniques for the combined system are also discussed.

Selective etching of InN over GaN and AlN, and of GaAs over both AlGaAs and InGaP was examined with a number of different plasma chemistries under inductively coupled plasma conditions. Selectivities up to 55 for InN/GaN and 20 for InN/AlN were achieved in IC1/Ar discharges. For GaAs/AlGaAs, maximum selectivities of 75(with BCl3/SF6) were obtained while for GaAs/InGaP values of 80(with BCl3/SF6) and 25(with BCl3/NF3) were achieved. Selective etching of InGaP over GaAs is possible with either CH4/H2 or BI3. The selectivity is a strong function of ion flux and ion energy, and can result from two factors – either formation of a nonvolatile etch product, or a difference in bond strength between the two materials.