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A 2 × 2 square pixel In0.5Ga0.5P p+-i-n+ mesa photodiode array was fabricated and investigated for its suitability in photon counting X-ray and γ-ray spectroscopy. Each pixel, which had an area of 200μm×200μm and a 5μm thick i layer, was coupled to a low-noise charge-sensitive preamplifier and standard onwards readout electronics to form an X-ray and γ-ray photon counting spectrometer. The pixels were illuminated in turn with an 55Fe radioisotope X-ray source, an 241Am radioisotope X-ray and γ-ray source, and a 109Cd radioisotope X-ray and γ-ray source. The mean value (across all pixels) of the best energy resolution (Full Width at Half Maximum, FWHM) at 20 °C was 770 eV ± 30 eV at 5.9 keV, 840 eV ± 20 eV at 22.16 keV, and 870 eV ± 30 eV at 59.54 keV. The spectroscopic response of one of the pixels was then investigated at temperatures up to 100 °C; noise analysis was performed and the different noise contributions were identified. The FWHM at 100 °C was 1.29 keV ± 0.04 keV at 5.9 keV, 1.32 keV ± 0.06 keV at 22.16 keV, 1.34 keV ± 0.06 keV at 59.54 keV, and 1.43 keV ± 0.08 keV at 88.03 keV. The results indicate that the detector did not suffer from incomplete charge collection, and that the spectrometer had better energy resolution at 100 °C than any other multi-pixel radiation spectrometer so far reported.

A commercial-off-the-shelf (COTS) Si p+-i-n+ photodiode (Hamamatsu S5973), designed for visible and infrared detection, was repurposed for use as a low-cost and readily available detector for photon counting X-ray and γ-ray spectroscopy. The detector was investigated for its spectroscopic performance, while being coupled to a custom-made charge sensitive preamplifier, under the illumination of photons with energies up to 59.54 keV. The detector-preamplifier system was subjected to temperatures from 80 °C to 20 °C. Energy resolutions (Full Width at Half Maximum, FWHM) of 0.66 keV ± 0.05 keV at 5.9 keV, 0.70 keV ± 0.04 keV at 22.16 keV, and 0.74 keV ± 0.06 keV at 59.54 keV, were achieved at 20 °C. The energy resolution deteriorated at 80 °C, reaching a value of 1.8 keV ± 0.1 keV FWHM at 59.54 keV. The results suggested that the performance, in terms of energy resolution, of the currently reported COTS Si detector was better than that achieved with certain purpose-grown wide bandgap detectors at 20 °C and 40 °C and better than that achieved with other repurposed Si detectors at 20 °C, opening new possibilities for applications for the Hamamatsu S5973 detectors and increasing the availability of low cost X-ray and γ-ray spectroscopy instrumentation.

info:eu-repo/semantics/published

This paper investigates the effects of temperature on an InGaP (GaInP) 55Fe X-ray photovoltaic cell prototype for a radioisotope microbattery (also called a nuclear microbattery). An In0.5Ga0.5P p-i-n (5 μm i-layer) mesa photodiode was illuminated by a standard 206 MBq 55Fe radioisotope X-ray source and characterised over the temperature range −20 °C to 100 °C. The electrical power output of the device reached its maximum value of 1.5 pW at a temperature of −20 °C. An open circuit voltage and a short circuit current of 0.82 V and 2.5 pA, respectively, were obtained at −20 °C. While the electrical power output and the open circuit voltage decreased with increasing temperature, an almost flat trend was found for the short circuit current. The cell conversion efficiency decreased from 2.1% at −20 °C to 0.7% at 100 °C.

A GaAs p+-i-n+ photodiode detector with a 30 μm thick i layer and a 400 μm diameter was processed using standard wet chemical etching from material grown by molecular beam epitaxy. The detector was characterized for its electrical and photon counting X-ray spectroscopic performance at temperatures from 60°C to -20 °C. The leakage current of the detector decreased from 1.247 nA ± 0.005 nA (= 0.992 μA/cm2 ± 0.004 μA/cm2) at 60 °C to 16.0 pA ± 0.5 pA (= 12.8 nA/cm2 ± 0.4 nA/cm2) at -20 °C, at the maximum investigated applied reverse bias, -100 V (corresponding to an applied electric field of 33 kV/cm). An almost uniform effective carrier concentration of 7.1 × 1014 cm-3 ± 0.7 × 1014 cm-3 was found at distances between 1.7 μm and 14 μm below the p+-i junction, which limited the depletion width to 14 μm ± 1 μm, at the maximum applied reverse bias (-100 V). Despite butterfly defects having formed during the epitaxial growth, 55 Fe X-ray spectra were successfully obtained with the detector coupled to a custom-made charge-sensitive preamplifier; the best energy resolution (Full Width at Half Maximum at 5.9 keV) improved from 1.36 keV at 60 °C to 0.73 keV at -20 °C. Neither the leakage current nor the capacitance of the GaAs detector were found to be the limiting factors of the energy resolution of the spectroscopic system; noise analysis at 0 °C and -20 °C revealed that the dominant source of noise was the quadratic sum of the dielectric and incomplete charge collection noise.

The average energy consumed in the generation of an electron–hole pair (ε AlInP ) in Al 0.52 In 0.48 P was experimentally measured across the temperature range −20 °C to 100 ∘ C, using a custom AlInP X-ray-photodiode, an 55 Fe radioisotope X-ray source, and custom low-noise charge-sensitive preamplifier electronics. ε AlInP was found to linearly decrease with increasing temperature according to the equation ε AlInP = (-0.0033 eV/K ± 0.0003 eV/K)T + (6.31 eV ± 0.10 eV). At room temperature (20 °C), ε AlInP = 5.34 eV ± 0.07 eV.

The average energy consumed in the generation of an electron–hole pair (εAlInP) in Al0.52In0.48P was experimentally measured across the temperature range −20 °C to 100 °C, using a custom AlInP X-ray-photodiode, an 55Fe radioisotope X-ray source, and custom low-noise charge-sensitive preamplifier electronics. εAlInP was found to linearly decrease with increasing temperature according to the equation εAlInP = (-0.0033 eV/K ± 0.0003 eV/K)T + (6.31 eV ± 0.10 eV). At room temperature (20 °C), εAlInP = 5.34 eV ± 0.07 eV.

A prototype InGaP p+–i–n+ mesa photodiode was studied for its potential as the energy conversion device in a 63Ni betavoltaic cell; its electrical performance was analysed across the temperature range −20 °C to 100 °C. The results show that the InGaP detector when illuminated with a laboratory 63Ni radioisotope beta particle source had a maximum output power of 0.92 pW at −20 °C, this value decreased at higher temperatures. A decrease in the open circuit voltage and in the cell internal conversion ef ciency were also observed when the temperature was increased: at −20 °C, the open circuit voltage and the cell internal conversion ef ciency had values of 0.69 V and 4%, respectively. A short circuit current of 4.5 pA was measured at −20 °C.

A prototype InGaP p+–i–n+ mesa photodiode was studied for its potential as the energy\ud conversion device in a 63Ni betavoltaic cell; its electrical performance was analysed across\ud the temperature range −20 °C to 100 °C. The results show that the InGaP detector when\ud illuminated with a laboratory 63Ni radioisotope beta particle source had a maximum output\ud power of 0.92 pW at −20 °C, this value decreased at higher temperatures. A decrease in the\ud open circuit voltage and in the cell internal conversion efficiency were also observed when the\ud temperature was increased: at −20 °C, the open circuit voltage and the cell internal conversion\ud efficiency had values of 0.69 V and 4%, respectively. A short circuit current of 4.5 pA was\ud measured at −20 °C.

In this paper, for the first time an InGaP (GaInP) photon counting X-ray photodiode has been developed and shown to be suitable for photon counting X-ray spectroscopy when coupled to a low-noise charge-sensitive preamplifier. The characterisation of two randomly selected 200 μm diameter and two randomly selected 400 μm diameter In 0.5 Ga 0.5 P p + -i-n + mesa photodiodes is reported; the i-layer of the p + -i-n + structure was 5 μm thick. At room temperature, and under illumination from an 55 Fe radioisotope X-ray source, X-ray spectra were accumulated; the best spectrometer energy resolution (FWHM) achieved at 5.9 keV was 900 eV for the 200 μm In 0.5 Ga 0.5 P diameter devices at reverse biases above 5 V. System noise analysis was also carried out and the different noise contributions were computed.

This paper describes the performance of a fabricated prototype Al0.2Ga0.8As 55Fe radioisotope microbattery photovoltaic cells over the temperature range −20 °C to 50 °C. Two 400 μm diameter p+-i-n+ (3 μm i-layer) Al0.2Ga0.8As mesa photodiodes were used as conversion devices in a novel X-ray microbattery prototype. The changes of the key microbattery parameters were analysed in response to temperature: the open circuit voltage, the maximum output power and the internal conversion efficiency decreased when the temperature was increased. At −20 °C, an open circuit voltage and a maximum output power of 0.2 V and 0.04 pW, respectively, were measured per photodiode. The best internal conversion efficiency achieved for the fabricated prototype was only 0.95% at −20 °C.

An Al0.52In0.48P 55Fe radioisotope microbattery is demonstrated over the temperature range −20 °C to 160 °C. Al0.52In0.48P p+-i-n+ mesa structures were used to collect the photons from a 238 MBq 55Fe radioisotope x-ray source. The effects of temperature on the key microbattery parameters were studied. Increasing the temperature, the saturation current increased; whilst the open circuit voltage, the maximum power and the conversion efficiency decreased. An open circuit voltage of 0.97V and a conversion efficiency of 22% were measured in a single p+-i-n+ mesa structure at −20 °C. The highest total microbattery maximum output power using two mesa structures was 1.2 pW at −20 °C.

Fluid viscoelastic dampers are of great interest in different fields of engineering. Examples of their applications can be found in seismic mitigation design of structures or in vibration absorption in airplane suspension. Such devices introduce a non-linear dissipative term in the equation of motion and therefore, the solution of even a single degree of freedom system excited by a white noise process, becomes prohibitive. The solution is usually obtained by approximated methods, like the stochastic linearization technique. In this paper it is shown that, by means of fractional operators, it is possible to find the solution of oscillators provided with fluid viscoelastic devices, approaching the problem in its originally nonlinear form. Comparison with solutions obtained by Monte Carlo simulation are finally discussed.