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.

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.

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/.

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.

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.

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.