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Richter D.,Max Planck Institute for Evolutionary Anthropology | Richter D.,Lüneburg University | Richter D.,Freiberg Instruments GmbH | Grun R.,Australian National University | And 18 more authors.
Nature | Year: 2017

The timing and location of the emergence of our species and of associated behavioural changes are crucial for our understanding of human evolution. The earliest fossil attributed to a modern form of Homo sapiens comes from eastern Africa and is approximately 195 thousand years old, therefore the emergence of modern human biology is commonly placed at around 200 thousand years ago. The earliest Middle Stone Age assemblages come from eastern and southern Africa but date much earlier. Here we report the ages, determined by thermoluminescence dating, of fire-heated flint artefacts obtained from new excavations at the Middle Stone Age site of Jebel Irhoud, Morocco, which are directly associated with newly discovered remains of H. sapiens. A weighted average age places these Middle Stone Age artefacts and fossils at 315 ± 34 thousand years ago. Support is obtained through the recalculated uranium series with electron spin resonance date of 286 ± 32 thousand years ago for a tooth from the Irhoud 3 hominin mandible. These ages are also consistent with the faunal and microfaunal assemblages and almost double the previous age estimates for the lower part of the deposits. The north African site of Jebel Irhoud contains one of the earliest directly dated Middle Stone Age assemblages, and its associated human remains are the oldest reported for H. sapiens. The emergence of our species and of the Middle Stone Age appear to be close in time, and these data suggest a larger scale, potentially pan-African, origin for both. © 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.


Grant
Agency: European Commission | Branch: FP7 | Program: CP | Phase: ICT-2013.3.3 | Award Amount: 11.05M | Year: 2013

SEA4KET (Semiconductor Equipment Assessment for Key Enabling Technologies) is an IP proposal taking the consequent step from equipment R&D to equipment assessment experiments. The strategic objective is to effectively combine resources and expertise in a joint assessment of novel equipment for key enabling technologies to foster and accelerate the successful transfer of novel European equipment into the world-wide market.\nSEA4KET builds on the proven principle established in previous European SEA programs and projects: to take novel, innovative and promising equipment that has left the R&D phase into a joint assessment activity this bridges the well-known gap between the phase of having an engineered tool available and finding the first user and finally success in the market for it.\nWhile proven principles from previous SEA activities are kept, SEA4KET takes them to the new field of assessing equipment for Key Enabling Technologies: SEA4KET concentrates on process and metrology systems for important enablers of future technologies: 450 mm wafer equipment, SiC material and 3D processing. The proposal comprises 15 sub-projects each dedicated to a specific equipment. The assessment activities were to a lesser extent chosen by high S&T excellence, but by their expected chance on the market.\nWhile leading R&D institutes are active in each assessment experiment to support individual final developments, several cross-cut R&D activities were identified (and combined in a dedicated sub-project) that are relevant to multiple assessments. Training material will be provided and workshops will be organized, to support and strengthen the individual dissemination activities.\nSEA4KET will significantly strengthen the European equipment and material industry for the emerging market for Key Enabling Technologies in a sustainable way by combining advanced R&D with equipment assessment involving users, institutes and equipment suppliers with specific benefit for SME suppliers.


Schuler N.,Freiberg Instruments GmbH | Hahn T.,TU Bergakademie Freiberg | Dornich K.,Freiberg Instruments GmbH | Niklas J.R.,Freiberg Instruments GmbH | Grundig-Wendrock B.,Solar World Innovations GmbH
Solar Energy Materials and Solar Cells | Year: 2010

Simulations of time dependent carrier profiles for thick as-grown silicon samples (e.g. ingots) were computed for the excitation conditions of two different transient photoconductance lifetime measurement methods. The simulations were performed using a partial differential equation system that allows computing also non-steady state conditions. The specific effective lifetimes for different measurement conditions can be extracted and compared. Simulation results and measurement results for μPCD (microwave detected photoconductivity decay), a non-steady state method and MDP (microwave detected photoconductivity), which operates typically with a steady state photo generation, were simulated and measured. It was found that the effective lifetimes measured at thick samples with each method may differ strongly. This discrepancy can be attributed to the different penetration depths of the laser light and microwave, but first and foremost to a varying light pulse length and its influence on the developing carrier profile. Altogether the MDP measurements or methods with a steady state photo generation in general are less prone to the surface impact and accordingly better suited for investigating the bulk properties of silicon samples. © 2010 Elsevier B.V. All rights reserved.


Berger B.,TU Bergakademie Freiberg | Schuler N.,Freiberg Instruments GmbH | Anger S.,Freiberg Instruments GmbH | Grundig-Wendrock B.,Solar World Innovations GmbH | And 2 more authors.
Physica Status Solidi (A) Applications and Materials Science | Year: 2011

The contactless electrical characterization techniques MDP and MD-PICTS will be presented in this paper. Both methods are predestined for defect investigation in a variety of semiconductors. Due to a so far not reached sensitivity, major advantages of MDP are its high spatial resolution and its measurement speed, which allows for two dimensional inline measurements at production speed. Furthermore a versatile numerical tool for simulations of electrical properties of a semiconductor as a function of defect parameters was developed. MD-PICTS is a contactless temperature dependent measurement which allows the determination of activation energies of trap levels in the material. To demonstrate the abilities of both methods, measurements conducted at different semiconductor materials, e.g. silicon, silicon carbide, gallium arsenide and indium phosphide, will be presented exemplarily. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Walter D.,Fraunhofer Institute for Solar Energy Systems | Walter D.,Institute for Solar Energy Research Hamelin | Rosenits P.,Fraunhofer Institute for Solar Energy Systems | Berger B.,TU Bergakademie Freiberg | And 3 more authors.
Progress in Photovoltaics: Research and Applications | Year: 2014

The effective minority carrier lifetimes on epitaxial silicon thin-film material have been measured successfully using two independent microwave-detected photoconductivity decay setups. Both measurement setups are found to be equally suited to determine the minority carrier lifetime of crystalline silicon thin-film (cSiTF) material. The different measurement conditions to which the sample under investigation is exposed are critically analyzed by both simulations and measurements on a large number of lifetime samples. No systematic deviation between the lifetime results from different measurement setups could be observed, underlining the accuracy of the determined lifetime value. Subsequently, a method to separate the epitaxial bulk lifetime and the total recombination velocity, consisting of front surface and interface recombination between the epitaxial layer and the substrate, is presented. The method, based on different thicknesses of the epitaxial layer, is applied to all batches of this investigation. Each batch consists of samples with the same material quality but different epitaxial layer thicknesses whereas different batches differ in their material quality. In addition, the same method is also successfully applied on individual cSiTF samples. From the results, it can be concluded that the limiting factor of the effective minority carrier lifetime for the investigated solar-grade cSiTF material is the elevated recombination velocity at the interface between epitaxial layer and the substrate compared with microelectronic-grade material. In contrast, the samples cannot be classified into different material qualities by their epitaxial bulk lifetimes. Even on multicrystalline substrate, solar-grade material can exhibit high epitaxial bulk lifetimes comparable to microelectronic-grade material. Copyright © 2012 John Wiley & Sons, Ltd. The effective carrier lifetime of crystalline silicon thin-film material has been measured on a wide range of different material qualities using two independent microwave-detected photoconductivity decay setups. No systematic deviation between the two measurement setups could be observed. Through a variation of the epitaxial layer thickness, the recombination in the interface region between the layer and the underlying substrate has been identified to be the limiting factor of the effective lifetimes. Copyright © 2012 John Wiley & Sons, Ltd.


Richter D.,Max Planck Institute for Evolutionary Anthropology | Richter D.,University of Bayreuth | Krbetschek M.,TU Bergakademie Freiberg | Krbetschek M.,Freiberg Instruments GmbH
Journal of Human Evolution | Year: 2015

Thermoluminescence (TL) data are presented for eight samples of heated flint collected at the archaeological site of Schöningen 13/I-1 (Cycle I), for which a Holsteinian age is suggested by palynology of stratigraphically similar positions within a cyclic sedimentological model for the Quaternary sequence of Schöningen. Although the fire responsible for the zeroing of the TL-signal cannot be unequivocally attributed to human activities, any time difference between a natural fire and the human occupation is negligible for a site of this antiquity. The weighted mean age of 321±16ka places the last heating of the flints nominally in the age range of Marine Isotope Stages (MIS) 10 to 8. By inference this data would suggest an attribution of the Holsteinian to MIS 9 and may also serve as a maximum age estimate for the spear site of Schöningen 13/II-4 (Cycle II). Considering the chronometric data available and following an alternative sedimentological model the age of these two sites at Schöningen can be considered as belonging to the same climatic cycle. This suggests an attribution to MIS 9, and by inference provides an age estimate of 337-300ka for the oldest spears in human history. © 2015 Elsevier Ltd.


Richter D.,Freiberg Instruments GmbH | Richter D.,University of Bayreuth | Richter A.,Freiberg Instruments GmbH | Dornich K.,Freiberg Instruments GmbH
Geochronometria | Year: 2013

The newly developed lexsyg system by Freiberg Instruments is a versatile luminescence reader, suited for research on the luminescence of materials, fundamental research in luminescence dating, but also for routine mass measurements in retrospective dosimetry as well as in dating applica-tion. The 80 sample storage wheel is disconnected from the measurement chamber and therefore crosstalk of optical stimulation is absent and cross-irradiation is negligible from the α- and β-sources, which are providing very uniform irradiations, with the latter especially designed for radiofluores-cence (RF) measurement. Optical excitation sources and filter wheels to vary detection wavelengths can be programmed to change at almost any time within measurement sequences, including the auto-mated change of an optional wheel holding up to four different detectors. Thermoluminescence meas-urements and preheating are possible with a versatile heater, which can be programmed for linear or non-linear heating or cooling, as well as holding a temperature constant. Rates as well as durations can be varied, together with individual ramping, staging and cooling for an almost unlimited number of steps. Violet- and IR-lasers, green and blue LED-arrays can be operated in continuous (CW) or modulated mode (linear/non-linear), and optionally for pulsed as well as time resolved luminescence detection. Six arrays of power LEDs allow the simulation of different bleaching regimes ('solar simu-lator'), while luminescence detection can be achieved by a variety of photomultiplier tubes and by CCD cameras for spatially resolved measurements and luminescence spectra. © 2013 Silesian University of Technology, Gliwice, Poland. All rights reserved.


Schuler N.,Freiberg Instruments GmbH | Anger S.,Freiberg Instruments GmbH | Dornich K.,Freiberg Instruments GmbH | Niklas J.R.,Freiberg Instruments GmbH | Bothe K.,Institute for Solar Energy Research Hamelin
Solar Energy Materials and Solar Cells | Year: 2012

The accuracy of photoconductance-based minority carrier lifetime measurement techniques is studied in detail. Regarding their accuracy and comparability, the quasi steady state photoconductance (QSSPC) as well as the novel steady state microwave detected photoconductivity (MDP) method are compared with the traditional microwave detected photoconductance decay (μPCD). We show that differences in measurement conditions and analyzing procedures lead to deviating results. Calculations based on a generalized rate equation system are used to model the photoconductivity and the resulting effective lifetime for different measurement conditions and defect models. The simulation results are compared to measurements on several mono- and multicrystalline silicon samples with and without surface passivation. Our results clearly show, that for low as well as high injection conditions deviations occur for the measurement and analysis techniques investigated. To allow for a comparison of lifetime data, we recommend to report exact measurement conditions and analysis procedures as well as to perform measurements in a certain injection range. Only if no trapping effects are present and the penetration depth of the applied method is significantly larger than the sample width, accurate and comparable lifetime results can be achieved. © 2011 Elsevier B.V. All rights reserved.


PubMed | Max Planck Institute for Evolutionary Anthropology, Freiberg Instruments GmbH, Justus Liebig University, Pintaske CONSULTING and Bordeaux Montaigne University
Type: | Journal: Applied radiation and isotopes : including data, instrumentation and methods for use in agriculture, industry and medicine | Year: 2016

A fully housed X-ray irradiator was developed for use within lexsyg or Magnettech desktop equipment. The importance of hardening of the low energy photon radiation is discussed, its performance and feasibility is empirically shown and sustained by basic numerical simulations. Results of the latter for various materials are given for different X-ray source settings in order to provide estimates on the required setup for the irradiation of different geometries and materials. A Si-photodiode provides real-time monitoring of the X-ray-irradiator designed for use in dosimetric dating and other dosimetric application where irradiation of small samples or dosemeters is required.


Dornich K.,Freiberg Instruments GmbH | Schuler N.,Freiberg Instruments GmbH | Berger B.,Freiberg Instruments GmbH | Niklas J.R.,Freiberg Instruments GmbH
Materials Science and Engineering B: Solid-State Materials for Advanced Technology | Year: 2013

The state-of-the art lifetime measurement technique MDP (microwave detected photoconductivity) is presented with its latest developments in sensitivity, measurement speed and data simulation. Several applications and examples in the field of inline material characterization, defect recognition and real time statistical process control in silicon bricks and wafers are presented, demonstrating the practical use of MDP measurements and of the data obtained by it. The measured lifetime itself combined with its spatial distribution and the measured steady state photoconductivity enable a good correlation to the cell efficiency. Furthermore, the paper presents a detailed summary of the properties of steady state and non-steady state microwave based minority carrier lifetime measurement techniques to complete this extensive study. © 2012 Elsevier B.V. All rights reserved.

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