[en] This paper explores an alternative to the standard method of studying the responsivities (the input—output gain) and other behaviours of detectors at low electron energy. The research does not aim to compare the results of differently doped n⁺p detectors; its purpose is to provide an alternative characterization method (using scanning electron microscopy) to those used in previous studies on the responsivity of n⁺p doped detectors as a function of the electron radiation energy and other interface parameters. (semiconductor devices)

[en] The ability to perform X-ray imaging with energy resolution on a small pixel detector is severely limited by the charge sharing in the detector. Different schemes have been proposed in order to overcome the problem. Previous studies using synchrotron radiation have shown that, for a 300-μm-thick Si detector with 55 μm pixel size, almost no charge sharing occurs for photons hitting the centre of each pixel. In this study, we have used slits to focus the beam from a standard X-ray unit onto the centre of a pixel for a MEDIPIX detector. The attenuation of the spectrum was measured for a number of samples of different materials with K-edge energy in the range of 30-50 keV. The measurements were performed by scanning an energy window through the spectrum. Requirements for new X-ray imaging systems with true energy resolution, based on these measurements, are discussed

[en] Highlights: ► Electrical conductivity is highly dependent on surface characteristics. ► Porosity and surface roughness are very important factors for conductivity. ► Surface energy is a minor factor for absorbing and rough substrates. ► If well behaved, porosity and roughness can be harmless or even beneficial. ► Paper substrates can be high performance substrates for metal nanoparticle inks. - Abstract: The widespread usage of paper and board offer largely unexploited possibilities for printed electronics applications. Reliability and performance of printed devices on comparatively rough and inhomogenous surfaces of paper does however pose challenges. Silver nanoparticle ink has been deposited on ten various paper substrates by inkjet printing. The papers are commercially available, and selected over a range of different types and construction. A smooth nonporous polyimide film was included as a nonporous reference substrate. The substrates have been characterized in terms of porosity, absorption rate, apparent surface energy, surface roughness and material content. The electrical conductivity of the resulting printed films have been measured after drying at 60 °C and again after additional curing at 110 °C. A qualitative analysis of the conductivity differences on the different substrates based on surface characterization and SEM examination is presented. Measurable parameters of importance to the final conductivity are pointed out, some of which are crucial to achieve conductivity. When certain criteria of the surfaces are met, paper media can be used as low cost, but comparably high performance substrates for metal nanoparticle inks in printed electronics applications.

[en] Printed electronics is a rapidly developing field where many components can already be manufactured on flexible substrates by printing or by other high speed manufacturing methods. However, the functionality of even the most inexpensive microcontroller or other integrated circuit is, at the present time and for the foreseeable future, out of reach by means of fully printed components. Therefore, it is of interest to investigate hybrid printed electronics, where regular electrical components are mounted on flexible substrates to achieve high functionality at a low cost. Moreover, the use of paper as a substrate for printed electronics is of growing interest because it is an environmentally friendly and renewable material and is, additionally, the main material used for many packages in which electronics functionalities could be integrated. One of the challenges for such hybrid printed electronics is the mounting of the components and the interconnection between layers on flexible substrates with printed conductive tracks that should provide as low a resistance as possible while still being able to be used in a high speed manufacturing process. In this article, several conductive adhesives are evaluated as well as soldering for mounting surface mounted components on a paper circuit board with ink-jet printed tracks and, in addition, a double sided Arduino compatible circuit board is manufactured and programmed. (paper)

[en] Pixellated silicon detectors with a thickness of 300 and 700 μm bonded to the MEDIPIX2 readout chip have been characterised using a monoenergetic microbeam at the ESRF. The spectral response when a 10x10 μm² wide 40 keV beam is centred on a single pixel is achieved. When the beam is scanned over the pixel, the charge sharing will increase when the beam approaches the border of the pixel. The experimental results have been verified by charge transport simulations and X-ray scattering simulations. Agreement between measurements and simulations can be achieved if a wider beam is assumed in the simulations. Widening of the absorption profile can to a large extent be explained by backscattering of lower-energy photons by the tin/led bump bounds below the detector. Widening of the detected beam is also an effect of angular alignment problems, especially on the 700 μm detector. Since the angel between the depth and a half-pixel is only 2.2^o, alignment of thick pixellated silicon detectors will be a problem to consider when designing X-ray imaging setups

[en] High-power, single-frequency, pulsed fiber amplifiers are required in light detection and ranging, coherent laser detection, and remote sensing applications to reach long range within a short acquisition time. However, the power-scaling of these amplifiers is limited by nonlinearities generated in the optical fibers, in particular by stimulated Brillouin scattering (SBS). In this regard, the use of multicomponent phosphate glasses maximizes the energy extraction and minimizes nonlinearities. Here, we present the development of a single-stage, hybrid, pulsed fiber amplifier using a custom-made multicomponent Yb-doped phosphate fiber. The performance of the phosphate fiber was compared to a commercial Yb-doped silica fiber. While the latter showed SBS limitation at nearly 6.5 kW for 40 cm length, the maximum achieved output peak power for the multicomponent Yb-doped phosphate fiber was 11.7 kW for 9 ns pulses using only 20 cm with no sign of SBS. (paper)