In the thirteenth century AD, the city of Karakorum was founded as the capital of the Mongol Empi... more In the thirteenth century AD, the city of Karakorum was founded as the capital of the Mongol Empire. Relatively little archaeological attention, however, has been directed at the site and the phenomenon of steppe urbanism. The authors report new magnetic and topographic surveys of the walled city and the surrounding landscape. The resulting maps reveal the city in unprecedented detail. Combining the magnetic and topographical data with aerial photographs, pedestrian surveys and documentary sources reveals the extent, layout and organisation of this extensive settlement. Road networks and areas of variable occupation density and types of activities deepen our understanding of this important commercial hub and royal palace, which is conceptualised as a form of ‘implanted’ urbanism.
Superconducting niobium nitride (NbN) films with nominal thicknesses of 4 nm, 5 nm, 7 nm, and 9 n... more Superconducting niobium nitride (NbN) films with nominal thicknesses of 4 nm, 5 nm, 7 nm, and 9 nm were grown on sapphire substrates using atomic layer deposition (ALD). We observed probed Hall resistance (HR) (Rxy) in external out-of-plane magnetic fields up to 6 T and magnetoresistance (MR) (Rxx) in external in-plane and out-of-plane magnetic fields up to 6 T on NbN thin films in Van der Pauw geometry. We also observed that positive MR dominated. Our study focused on the analysis of interaction and localisation effects on electronic disorder in NbN in the normal state in temperatures that ranged from 50 K down to the superconducting transition temperature. By modelling the temperature and magnetic field dependence of the MR data, we extracted the temperature-dependent Coulomb interaction constants, spin–orbit scattering lengths, localisation lengths, and valley degeneracy factors. The MR model allowed us to distinguish between interaction effects (positive MR) and localisation eff...
Wetland environments, with their excellent conservation conditions, provide geoarchaeological arc... more Wetland environments, with their excellent conservation conditions, provide geoarchaeological archives of past human activities. However, the subsurface soil is difficult to access due to high groundwater tables, unstable sediments, and the high cost of excavation. In this study, we present a ground-based non- and minimal-invasive prospection concept adapted to the conditions of wetlands. We investigated the Fossa Carolina in South Germany, a canal that was intended in 792/793 AD by Charlemagne to bridge the Central European Watershed. Although the resulting Carolingian banks and the fairway with wooden revetments are very imposing, archaeological traces of off-site construction activities have not been identified hitherto. Based on a geophysically surveyed intensive linear magnetic anomaly parallel to the Carolingian canal, we aimed to prove potential off-site traces of Carolingian construction activities. In this context, we built up a high-resolution cross-section using highly depth-accurate direct push sensing and ground-truthing. Our results showed the exact geometry of the canal and the former banks. Thus, the magnetic mass anomaly could be clearly located between the buried organic-rich topsoil and the Carolingian banks. The thermoluminescence dating showed that the position of the magnetic mass anomaly reflected Carolingian activities during the construction phases, specifically due to heat exposure. Moreover, we found hints of the groundwater supply to the 5-metre wide navigable fairway.
Sediment budgeting concepts serve as quantification tools to decipher the erosion and accumulatio... more Sediment budgeting concepts serve as quantification tools to decipher the erosion and accumulation processes within a catchment and help to understand these relocation processes through time. While sediment budgets are widely used in geomor-phological catchment-based studies, such quantification approaches are rarely applied in geoarchaeological studies. The case of Charlemagne's summit canal (also known as Fossa Carolina) and its erosional collapse provides an example for which we can use this geomorphological concept and understand the abandonment of the Carolingian construction site. The Fossa Carolina is one of the largest hydro-engineering projects in Medieval Europe. It is situated in Southern Franconia (48.9876°N, 10.9267°E; Bavaria, southern Germany) between the Altmühl and Swabian Rezat rivers. It should have bridged the Central European watershed and connected the Rhine-Main and Danube river systems. According to our dendrochronological analyses and historical sources, the excavation and construction of the Carolingian canal took place in AD 792 and 793. Contemporary written sources describe an intense backfill of excavated sediment in autumn AD 793. This short-term erosion event has been proposed as the principal reason for the collapse and abandonment of the hydro-engineering project. We use subsurface data (drillings, archaeological excavations , and direct-push sensing) and geospatial data (a LiDAR digital terrain model (DTM), a pre-modern DTM, and a 3D model of the Fossa Carolina] for the identification and sediment budgeting of the backfills. Dendrochronological findings and radiocarbon ages of macro remains within the backfills give clear evidence for the erosional collapse of the canal project during or directly after the construction period. Moreover, our quantification approach allows the detection of the major sedimentary collapse zone. The exceedance of the manpower tipping point may have caused the abandonment of the entire construction site. The spatial distribution of the dendrochronological results indicates a north-south direction of the early medieval construction progress.
Abstract The prospection of (geo-)archaeological sites yield important knowledge about the concep... more Abstract The prospection of (geo-)archaeological sites yield important knowledge about the concept and the utilisation of pre-historical and historical infrastructure. The satisfactory conduction of classical prospection methods like archaeological excavations or geoarchaeological vibra-coring might be challenging in the case of large sites or difficult underground conditions. This is particularly problematic in wetlands featuring a high groundwater table and high compaction rates of organic layers. In this study, we provide an alternative and non- to minimal-invasive exploration approach to discover hydro-engineering structures for artificial water supply in the surrounding of a Carolingian summit canal in South Germany. The Early Medieval Fossa Carolina was intended 792/793 CE to bridge the Central European watershed between Rhine-Main and Danube catchments. As the canal was constructed as a summit canal, an artificial water supply at the highest levels seemed very likely or even obligatory. In order to explore these obligatory hydro-engineering features, we use a wide range of on-site and off-site tools in a spatial hierarchical way. Our approach includes the large-scale SQUID magnetic survey and the sighting of historical maps. Furthermore, we integrate high-resolution direct push colour logs, and subsequent vibra-coring for small-scale stratigraphical verification and sedimentological analyses. The SQUID magnetic survey and related depth models discover two pronounced linear anomalies that might represent potential artificial water inlets in the North-Eastern and Northern Sections of the canal. I) In the North-Eastern Section, direct push colour logs, vibra-coring and 14C dating provide no evidence for a Carolingian hydro-engineering feature but reveal a natural lenticular structure of Early Holocene age. II) The linear magnetic anomaly in the Northern Section can be excluded with high probability as a hydro-engineering structure as well. Here, direct push colour logs, vibra-coring, 14C dating and the comparison with a historic map reveal evidence for a historic gravel road. Thus, we have nicely verified the magnetic information but have no prove for an artificial Carolingian water inlet from the Swabian Rezat River that contradicts with assumptions of former studies.
The Early Medieval Fossa Carolina is the first hydro-engineering construction that bridges the Ce... more The Early Medieval Fossa Carolina is the first hydro-engineering construction that bridges the Central European Watershed. The canal was built in 792/793 AD on order of Charlemagne and should connect the drainage systems of the Rhine-Main catchment and the Danube catchment. In this study, we show for the first time, the integration of Airborne LiDAR (Light Detection and Ranging) and geoarchaeological subsurface datasets with the aim to create a 3D-model of Charlemagne's summit canal. We used a purged Digital Terrain Model that reflects the pre-modern topography. The geometries of buried canal cross-sections are derived from three archaeological excavations and four high-resolution direct push sensing transects. By means of extensive core data, we interpolate the trench bottom and adjacent edges along the entire canal course. As a result, we are able to create a 3D-model that reflects the maximum construction depth of the Carolingian canal and calculate an excavation volume of approx. 297,000 m 3. Additionally, we compute the volume of the present dam remnants by Airborne LiDAR data. Surprisingly, the volume of the dam remnants reveals only 120,000 m 3 and is much smaller than the computed Carolingian excavation volume. The difference reflects the erosion and anthropogenic overprint since the 8th century AD.
Abstract The full waveform inversion (FWI) of strongly dispersive Love wave data is a challenging... more Abstract The full waveform inversion (FWI) of strongly dispersive Love wave data is a challenging task. Amplitude, phase and dispersion information not only depends on the density and shear modulus distribution in the subsurface, but also significantly on intrinsic damping. This is especially a problem in near surface data applications with complex underground structures and low Qs values. Therefore, the FWI of a dispersive Love wavefield demands an accurate initial visco-elastic model and careful data pre-processing. Another key ingredient of a successful time-domain FWI is the sequential inversion of frequency filtered data in order to mitigate the non-linearity of the inverse problem. Common FWI strategies are based solely on either low- or bandpass filtered data. In this study we develop an FWI workflow consisting of a combined low- and bandpass filter strategy to achieve an appropriate data fit of the low-frequency Love wave and high-frequency refracted SH-wavefield. The applicability of this FWI strategy and the importance of a visco-elastic medium description is demonstrated for SH field data from a transect over the Fossa Carolina, a silted medieval canal structure in southern Germany. The resolved canal shape and small scale structures in the inversion results are verified by an archaeological excavation.
The Early Medieval Fossa Carolina is the first hydro-engineering construction that bridges the Ce... more The Early Medieval Fossa Carolina is the first hydro-engineering construction that bridges the Central European Watershed. The canal was built in 792/793 AD on order of Charlemagne and should connect the drainage systems of the Rhine-Main catchment and the Danube catchment. In this study, we show for the first time, the integration of Airborne LiDAR (Light Detection and Ranging) and geoarchaeological subsurface datasets with the aim to create a 3D-model of Charlemagne’s summit canal. We used a purged Digital Terrain Model that reflects the pre-modern topography. The geometries of buried canal cross-sections are derived from three archaeological excavations and four high-resolution direct push sensing transects. By means of extensive core data, we interpolate the trench bottom and adjacent edges along the entire canal course. As a result, we are able to create a 3D-model that reflects the maximum construction depth of the Carolingian canal and calculate an excavation volume of approx...
In this manuscript we document a multidisciplinary approach in wetland geoarchaeology for detecti... more In this manuscript we document a multidisciplinary approach in wetland geoarchaeology for detecting artificial structures in a middle European floodplain. By means of a large set of different prospection methods (cadastral analysis, aerial archaeology, LiDAR, SQUID based magnetic prospection, electrical resistivity tomography, seismic refraction tomography, ground penetrating radar) and a subsequent geoarchaeological drilling campaign we provide an overview about the potentials and limits of the applied methods. Our site-specific aims focus on the Fossa Carolina, Charlemagne's shortcut for linking the Rhine-Main and the Altmühl-Danube inland navigation systems during the Early Middle Ages. Our results show that Altmühl meander loops were quasi stable since Carolingian times and that an Altmühl floodplaincrossing trench of at least 650e700 m was required for linking the Altmühl River with the e archaeological known e southernmost position of the existing Carolingian canal. However, our large set of remote sensing and geophysical prospection tools and the corresponding drilling campaign do not show any evidence for the missing Carolingian trench within the Altmühl floodplain. Our results support the idea that the Carolingian canal was never entirely completed although large parts of the canal were almost finished in the northern sections.
IEEE Transactions on Applied Superconductivity, 2017
This paper describes the deposition of superconductive Nb-N thin films in a metal-organic plasma-... more This paper describes the deposition of superconductive Nb-N thin films in a metal-organic plasma-enhanced atomic layer deposition process using (tert-butylimido)-tris (diethylamino)-niobium and hydrogen plasma as precursors. In extension of our previous work, which investigated the possibility to deposit superconducting Nb-N, we systematically investigated the influence of different plasma parameters on superconducting and morphological properties of the niobium nitride thin film formed during the process. An initial increase of the duration of the plasma dose led to higher transitions temperatures and critical current densities, the optimum being a plasma dose time of 50 s. By decreasing plasma pressure, the resistivity at room temperature decreased, while the transition temperature increased. In addition, Nb-N thin films were deposited onto several substrates such as silicon, thermally grown silica, magnesium oxide (MgO), and r-plane sapphire. T C values from 6.2 K up to 14 K were achieved independently of the substrate materials. However, films deposited on MgO showed lower T C values. X-ray photoelectron spectroscopy measurement revealed the presence of niobium nitride but also of niobium oxide and oxy-nitride components in the films as well as the existence of a high amount of incorporated carbon impurities. X-ray diffraction measurements revealed two significant reflexes, which could be attributed to niobium nitride only. No crystalline niobium oxide or niobium oxynitride was detected. Thus, the films consisted of a matrix of polycrystalline Nb-N and amorphous or microcrystalline grains of different niobium oxide and oxynitride phases. Due to the fact that the deposited material showed superconductivity especially for ultrathin layers with thicknesses in the nanometer range, these films may be suitable for superconducting nanowire single photon detectors.
IEEE Transactions on Applied Superconductivity, 2016
We have developed a thin-film fabrication process which allows manufacturing of Josephson junctio... more We have developed a thin-film fabrication process which allows manufacturing of Josephson junction-based devices from the same layout data either in the VTT foundry in Espoo, Finland, or in the FLUXONICS foundry at the IPHT in Jena, Germany. Automated scripts are used to derive either VTT compatible or FLUXONICS compatible mask plates from the same layout data. Test circuits have been fabricated at both foundries from the same layout data and their correct operation verified.
IEEE Transactions on Applied Superconductivity, 2016
We report on the development of an ultralow noise thin-film based SQUID magnetometer. A niobium t... more We report on the development of an ultralow noise thin-film based SQUID magnetometer. A niobium thin-film pickup coil is connected to the input coil of a SQUID current sensor. The low capacitance of the used sub-micrometer crosstype Josephson junctions enable superior noise performance of the device. Application scenarios e.g. in geophysics and ultra-low field magnetic resonance imaging are discussed.
Due to the ongoing improvement in nanostructuring technology, ultrathin metallic nanofilms have r... more Due to the ongoing improvement in nanostructuring technology, ultrathin metallic nanofilms have recently gained substantial attention in plasmonics, e.g. as building blocks of metasurfaces. Typically, noble metals such as silver or gold are the materials of choice, due to their excellent optical properties, however they also possess some intrinsic disadvantages. Here, we introduce niobium nanofilms (~10 nm thickness) as an alternate plasmonic platform. We demonstrate functionality by depositing a niobium nanofilm on a plasmonic fiber taper, and observe a dielectric-loaded niobium surface-plasmon excitation for the first time, with a modal attenuation of only 3-4 dB/mm in aqueous environment and a refractive index sensitivity up to 15 μm/RIU if the analyte index exceeds 1.42. We show that the niobium nanofilm possesses bulk optical properties, is continuous, homogenous, and inert against any environmental influence, thus possessing several superior properties compared to noble metal ...
Zusammenfassung: Zur Nutzungsanalyse großer ovaler, erstmalig entdeckter und dokumentierter von e... more Zusammenfassung: Zur Nutzungsanalyse großer ovaler, erstmalig entdeckter und dokumentierter von einem niedrigen Graben-Wall-System umgebener Anlagen wurden Bodenproben auf spezifische Lipide untersucht, die Hinweise auf die Anwesenheit – hinterlassene Verdauungsreste – bestimmter Nutztierarten und Menschen in den beprobten Bereichen geben könnten. Wahrscheinlich dienten die Anlagen dem Gartenbau, sicherlich nicht der Viehhaltung; in den angrenzenden Dachziegel und Keramikscherben aufweisenden viereckigen, deutlich kleineren umwallten Anlagen siedelten Menschen. Solche ovalen Anlagen sind in der Mongolei bisher nur aus dem Umfeld der uighurischen Hauptstadt Karabalgasun bekannt geworden, deren Stadtgebiet eine deutlich größere Fläche einnimmt als bisher angenommen wurde und vielteiliger sowie funktional gegliedert ist. Dieses erste stichpunktartige Ergebnis zeigt das Potential der Lipidanalysen, frühere Landnutzung zu rekonstruieren, beispielsweise Viehhaltung von acker- oder gartenb...
Between 2000 and 2005 archaeologists and students of the Institute of Archaeology, Mongolian Acad... more Between 2000 and 2005 archaeologists and students of the Institute of Archaeology, Mongolian Academy of Sciences, and the Department of Pre and Early Historical Archaeology, University of Bonn, excavated parts of a craftsmen quarter in the center of the old Mongolian capital Karakorum (Fig. 1) where — according to William of Rubruck, a Franciscan monk, who stayed there several months during spring 1254 (cf. Rubruck/Jackson 1990) — a Chinese population lived and worked in the 13 th century CE. The excavations in the center of the first capital of the Mongol Empire were carried out within the Mongolian–German Karakorum Expedition with the goal in the first instance of answering questions concerning the founding, the duration of settlement and the end of occupation of the entire town. In addition, interest focused on the profession and occupation of the people living in the urban center (Bemmann et al. 2010).
ABSTRACT This paper is based on data sets acquired by a fast and efficient ground-based measureme... more ABSTRACT This paper is based on data sets acquired by a fast and efficient ground-based measurement system, which is based on superconducting quantum interference device technology and ensures geo-magnetic mapping of large areas. The local variations (gradients) of the Earth's magnetic field are represented in so-called magnetograms, which typically include a large number of magnetic anomalies with different appearance and shape. Here, elongated anomalies are investigated, which are explainable by a polyhedral source body. These underground structures can be represented by a cross section that is approximately uniform along the main strike extent of the source. After introducing the measurement system, a source description model is developed theoretically and in the following adapted to practical problems. In order to illustrate the utility of this kind of minimization-based inversion and to validate the produced results, an example of archaeological measurements in Mongolia is shown. Results of the field measurements are used for inversion toward a description of possible subsoil situation. Finally, an excavation shows the accuracy of the results.
IEEE Transactions on Applied Superconductivity, 2013
ABSTRACT In Europe, the FLUXONICS Foundry develops fabrication processes and design kits for supe... more ABSTRACT In Europe, the FLUXONICS Foundry develops fabrication processes and design kits for superconductor digital and mixed-signal circuits. We describe the implementation of the “European Roadmap for Superconductor Electronics” into the recent foundry process for superconductor digital electronics. Following the hierarchical cell-based design strategy, we developed a design kit with basic cells. We present experimental results of the process quality, the verified operation margins of the library cells, and the results of low- and high-speed investigations of test circuits. The process is suitable for the integration of complex digital and mixed-signal circuits for smart multichannel superconductor sensor applications with a digital interface.
In the thirteenth century AD, the city of Karakorum was founded as the capital of the Mongol Empi... more In the thirteenth century AD, the city of Karakorum was founded as the capital of the Mongol Empire. Relatively little archaeological attention, however, has been directed at the site and the phenomenon of steppe urbanism. The authors report new magnetic and topographic surveys of the walled city and the surrounding landscape. The resulting maps reveal the city in unprecedented detail. Combining the magnetic and topographical data with aerial photographs, pedestrian surveys and documentary sources reveals the extent, layout and organisation of this extensive settlement. Road networks and areas of variable occupation density and types of activities deepen our understanding of this important commercial hub and royal palace, which is conceptualised as a form of ‘implanted’ urbanism.
Superconducting niobium nitride (NbN) films with nominal thicknesses of 4 nm, 5 nm, 7 nm, and 9 n... more Superconducting niobium nitride (NbN) films with nominal thicknesses of 4 nm, 5 nm, 7 nm, and 9 nm were grown on sapphire substrates using atomic layer deposition (ALD). We observed probed Hall resistance (HR) (Rxy) in external out-of-plane magnetic fields up to 6 T and magnetoresistance (MR) (Rxx) in external in-plane and out-of-plane magnetic fields up to 6 T on NbN thin films in Van der Pauw geometry. We also observed that positive MR dominated. Our study focused on the analysis of interaction and localisation effects on electronic disorder in NbN in the normal state in temperatures that ranged from 50 K down to the superconducting transition temperature. By modelling the temperature and magnetic field dependence of the MR data, we extracted the temperature-dependent Coulomb interaction constants, spin–orbit scattering lengths, localisation lengths, and valley degeneracy factors. The MR model allowed us to distinguish between interaction effects (positive MR) and localisation eff...
Wetland environments, with their excellent conservation conditions, provide geoarchaeological arc... more Wetland environments, with their excellent conservation conditions, provide geoarchaeological archives of past human activities. However, the subsurface soil is difficult to access due to high groundwater tables, unstable sediments, and the high cost of excavation. In this study, we present a ground-based non- and minimal-invasive prospection concept adapted to the conditions of wetlands. We investigated the Fossa Carolina in South Germany, a canal that was intended in 792/793 AD by Charlemagne to bridge the Central European Watershed. Although the resulting Carolingian banks and the fairway with wooden revetments are very imposing, archaeological traces of off-site construction activities have not been identified hitherto. Based on a geophysically surveyed intensive linear magnetic anomaly parallel to the Carolingian canal, we aimed to prove potential off-site traces of Carolingian construction activities. In this context, we built up a high-resolution cross-section using highly depth-accurate direct push sensing and ground-truthing. Our results showed the exact geometry of the canal and the former banks. Thus, the magnetic mass anomaly could be clearly located between the buried organic-rich topsoil and the Carolingian banks. The thermoluminescence dating showed that the position of the magnetic mass anomaly reflected Carolingian activities during the construction phases, specifically due to heat exposure. Moreover, we found hints of the groundwater supply to the 5-metre wide navigable fairway.
Sediment budgeting concepts serve as quantification tools to decipher the erosion and accumulatio... more Sediment budgeting concepts serve as quantification tools to decipher the erosion and accumulation processes within a catchment and help to understand these relocation processes through time. While sediment budgets are widely used in geomor-phological catchment-based studies, such quantification approaches are rarely applied in geoarchaeological studies. The case of Charlemagne's summit canal (also known as Fossa Carolina) and its erosional collapse provides an example for which we can use this geomorphological concept and understand the abandonment of the Carolingian construction site. The Fossa Carolina is one of the largest hydro-engineering projects in Medieval Europe. It is situated in Southern Franconia (48.9876°N, 10.9267°E; Bavaria, southern Germany) between the Altmühl and Swabian Rezat rivers. It should have bridged the Central European watershed and connected the Rhine-Main and Danube river systems. According to our dendrochronological analyses and historical sources, the excavation and construction of the Carolingian canal took place in AD 792 and 793. Contemporary written sources describe an intense backfill of excavated sediment in autumn AD 793. This short-term erosion event has been proposed as the principal reason for the collapse and abandonment of the hydro-engineering project. We use subsurface data (drillings, archaeological excavations , and direct-push sensing) and geospatial data (a LiDAR digital terrain model (DTM), a pre-modern DTM, and a 3D model of the Fossa Carolina] for the identification and sediment budgeting of the backfills. Dendrochronological findings and radiocarbon ages of macro remains within the backfills give clear evidence for the erosional collapse of the canal project during or directly after the construction period. Moreover, our quantification approach allows the detection of the major sedimentary collapse zone. The exceedance of the manpower tipping point may have caused the abandonment of the entire construction site. The spatial distribution of the dendrochronological results indicates a north-south direction of the early medieval construction progress.
Abstract The prospection of (geo-)archaeological sites yield important knowledge about the concep... more Abstract The prospection of (geo-)archaeological sites yield important knowledge about the concept and the utilisation of pre-historical and historical infrastructure. The satisfactory conduction of classical prospection methods like archaeological excavations or geoarchaeological vibra-coring might be challenging in the case of large sites or difficult underground conditions. This is particularly problematic in wetlands featuring a high groundwater table and high compaction rates of organic layers. In this study, we provide an alternative and non- to minimal-invasive exploration approach to discover hydro-engineering structures for artificial water supply in the surrounding of a Carolingian summit canal in South Germany. The Early Medieval Fossa Carolina was intended 792/793 CE to bridge the Central European watershed between Rhine-Main and Danube catchments. As the canal was constructed as a summit canal, an artificial water supply at the highest levels seemed very likely or even obligatory. In order to explore these obligatory hydro-engineering features, we use a wide range of on-site and off-site tools in a spatial hierarchical way. Our approach includes the large-scale SQUID magnetic survey and the sighting of historical maps. Furthermore, we integrate high-resolution direct push colour logs, and subsequent vibra-coring for small-scale stratigraphical verification and sedimentological analyses. The SQUID magnetic survey and related depth models discover two pronounced linear anomalies that might represent potential artificial water inlets in the North-Eastern and Northern Sections of the canal. I) In the North-Eastern Section, direct push colour logs, vibra-coring and 14C dating provide no evidence for a Carolingian hydro-engineering feature but reveal a natural lenticular structure of Early Holocene age. II) The linear magnetic anomaly in the Northern Section can be excluded with high probability as a hydro-engineering structure as well. Here, direct push colour logs, vibra-coring, 14C dating and the comparison with a historic map reveal evidence for a historic gravel road. Thus, we have nicely verified the magnetic information but have no prove for an artificial Carolingian water inlet from the Swabian Rezat River that contradicts with assumptions of former studies.
The Early Medieval Fossa Carolina is the first hydro-engineering construction that bridges the Ce... more The Early Medieval Fossa Carolina is the first hydro-engineering construction that bridges the Central European Watershed. The canal was built in 792/793 AD on order of Charlemagne and should connect the drainage systems of the Rhine-Main catchment and the Danube catchment. In this study, we show for the first time, the integration of Airborne LiDAR (Light Detection and Ranging) and geoarchaeological subsurface datasets with the aim to create a 3D-model of Charlemagne's summit canal. We used a purged Digital Terrain Model that reflects the pre-modern topography. The geometries of buried canal cross-sections are derived from three archaeological excavations and four high-resolution direct push sensing transects. By means of extensive core data, we interpolate the trench bottom and adjacent edges along the entire canal course. As a result, we are able to create a 3D-model that reflects the maximum construction depth of the Carolingian canal and calculate an excavation volume of approx. 297,000 m 3. Additionally, we compute the volume of the present dam remnants by Airborne LiDAR data. Surprisingly, the volume of the dam remnants reveals only 120,000 m 3 and is much smaller than the computed Carolingian excavation volume. The difference reflects the erosion and anthropogenic overprint since the 8th century AD.
Abstract The full waveform inversion (FWI) of strongly dispersive Love wave data is a challenging... more Abstract The full waveform inversion (FWI) of strongly dispersive Love wave data is a challenging task. Amplitude, phase and dispersion information not only depends on the density and shear modulus distribution in the subsurface, but also significantly on intrinsic damping. This is especially a problem in near surface data applications with complex underground structures and low Qs values. Therefore, the FWI of a dispersive Love wavefield demands an accurate initial visco-elastic model and careful data pre-processing. Another key ingredient of a successful time-domain FWI is the sequential inversion of frequency filtered data in order to mitigate the non-linearity of the inverse problem. Common FWI strategies are based solely on either low- or bandpass filtered data. In this study we develop an FWI workflow consisting of a combined low- and bandpass filter strategy to achieve an appropriate data fit of the low-frequency Love wave and high-frequency refracted SH-wavefield. The applicability of this FWI strategy and the importance of a visco-elastic medium description is demonstrated for SH field data from a transect over the Fossa Carolina, a silted medieval canal structure in southern Germany. The resolved canal shape and small scale structures in the inversion results are verified by an archaeological excavation.
The Early Medieval Fossa Carolina is the first hydro-engineering construction that bridges the Ce... more The Early Medieval Fossa Carolina is the first hydro-engineering construction that bridges the Central European Watershed. The canal was built in 792/793 AD on order of Charlemagne and should connect the drainage systems of the Rhine-Main catchment and the Danube catchment. In this study, we show for the first time, the integration of Airborne LiDAR (Light Detection and Ranging) and geoarchaeological subsurface datasets with the aim to create a 3D-model of Charlemagne’s summit canal. We used a purged Digital Terrain Model that reflects the pre-modern topography. The geometries of buried canal cross-sections are derived from three archaeological excavations and four high-resolution direct push sensing transects. By means of extensive core data, we interpolate the trench bottom and adjacent edges along the entire canal course. As a result, we are able to create a 3D-model that reflects the maximum construction depth of the Carolingian canal and calculate an excavation volume of approx...
In this manuscript we document a multidisciplinary approach in wetland geoarchaeology for detecti... more In this manuscript we document a multidisciplinary approach in wetland geoarchaeology for detecting artificial structures in a middle European floodplain. By means of a large set of different prospection methods (cadastral analysis, aerial archaeology, LiDAR, SQUID based magnetic prospection, electrical resistivity tomography, seismic refraction tomography, ground penetrating radar) and a subsequent geoarchaeological drilling campaign we provide an overview about the potentials and limits of the applied methods. Our site-specific aims focus on the Fossa Carolina, Charlemagne's shortcut for linking the Rhine-Main and the Altmühl-Danube inland navigation systems during the Early Middle Ages. Our results show that Altmühl meander loops were quasi stable since Carolingian times and that an Altmühl floodplaincrossing trench of at least 650e700 m was required for linking the Altmühl River with the e archaeological known e southernmost position of the existing Carolingian canal. However, our large set of remote sensing and geophysical prospection tools and the corresponding drilling campaign do not show any evidence for the missing Carolingian trench within the Altmühl floodplain. Our results support the idea that the Carolingian canal was never entirely completed although large parts of the canal were almost finished in the northern sections.
IEEE Transactions on Applied Superconductivity, 2017
This paper describes the deposition of superconductive Nb-N thin films in a metal-organic plasma-... more This paper describes the deposition of superconductive Nb-N thin films in a metal-organic plasma-enhanced atomic layer deposition process using (tert-butylimido)-tris (diethylamino)-niobium and hydrogen plasma as precursors. In extension of our previous work, which investigated the possibility to deposit superconducting Nb-N, we systematically investigated the influence of different plasma parameters on superconducting and morphological properties of the niobium nitride thin film formed during the process. An initial increase of the duration of the plasma dose led to higher transitions temperatures and critical current densities, the optimum being a plasma dose time of 50 s. By decreasing plasma pressure, the resistivity at room temperature decreased, while the transition temperature increased. In addition, Nb-N thin films were deposited onto several substrates such as silicon, thermally grown silica, magnesium oxide (MgO), and r-plane sapphire. T C values from 6.2 K up to 14 K were achieved independently of the substrate materials. However, films deposited on MgO showed lower T C values. X-ray photoelectron spectroscopy measurement revealed the presence of niobium nitride but also of niobium oxide and oxy-nitride components in the films as well as the existence of a high amount of incorporated carbon impurities. X-ray diffraction measurements revealed two significant reflexes, which could be attributed to niobium nitride only. No crystalline niobium oxide or niobium oxynitride was detected. Thus, the films consisted of a matrix of polycrystalline Nb-N and amorphous or microcrystalline grains of different niobium oxide and oxynitride phases. Due to the fact that the deposited material showed superconductivity especially for ultrathin layers with thicknesses in the nanometer range, these films may be suitable for superconducting nanowire single photon detectors.
IEEE Transactions on Applied Superconductivity, 2016
We have developed a thin-film fabrication process which allows manufacturing of Josephson junctio... more We have developed a thin-film fabrication process which allows manufacturing of Josephson junction-based devices from the same layout data either in the VTT foundry in Espoo, Finland, or in the FLUXONICS foundry at the IPHT in Jena, Germany. Automated scripts are used to derive either VTT compatible or FLUXONICS compatible mask plates from the same layout data. Test circuits have been fabricated at both foundries from the same layout data and their correct operation verified.
IEEE Transactions on Applied Superconductivity, 2016
We report on the development of an ultralow noise thin-film based SQUID magnetometer. A niobium t... more We report on the development of an ultralow noise thin-film based SQUID magnetometer. A niobium thin-film pickup coil is connected to the input coil of a SQUID current sensor. The low capacitance of the used sub-micrometer crosstype Josephson junctions enable superior noise performance of the device. Application scenarios e.g. in geophysics and ultra-low field magnetic resonance imaging are discussed.
Due to the ongoing improvement in nanostructuring technology, ultrathin metallic nanofilms have r... more Due to the ongoing improvement in nanostructuring technology, ultrathin metallic nanofilms have recently gained substantial attention in plasmonics, e.g. as building blocks of metasurfaces. Typically, noble metals such as silver or gold are the materials of choice, due to their excellent optical properties, however they also possess some intrinsic disadvantages. Here, we introduce niobium nanofilms (~10 nm thickness) as an alternate plasmonic platform. We demonstrate functionality by depositing a niobium nanofilm on a plasmonic fiber taper, and observe a dielectric-loaded niobium surface-plasmon excitation for the first time, with a modal attenuation of only 3-4 dB/mm in aqueous environment and a refractive index sensitivity up to 15 μm/RIU if the analyte index exceeds 1.42. We show that the niobium nanofilm possesses bulk optical properties, is continuous, homogenous, and inert against any environmental influence, thus possessing several superior properties compared to noble metal ...
Zusammenfassung: Zur Nutzungsanalyse großer ovaler, erstmalig entdeckter und dokumentierter von e... more Zusammenfassung: Zur Nutzungsanalyse großer ovaler, erstmalig entdeckter und dokumentierter von einem niedrigen Graben-Wall-System umgebener Anlagen wurden Bodenproben auf spezifische Lipide untersucht, die Hinweise auf die Anwesenheit – hinterlassene Verdauungsreste – bestimmter Nutztierarten und Menschen in den beprobten Bereichen geben könnten. Wahrscheinlich dienten die Anlagen dem Gartenbau, sicherlich nicht der Viehhaltung; in den angrenzenden Dachziegel und Keramikscherben aufweisenden viereckigen, deutlich kleineren umwallten Anlagen siedelten Menschen. Solche ovalen Anlagen sind in der Mongolei bisher nur aus dem Umfeld der uighurischen Hauptstadt Karabalgasun bekannt geworden, deren Stadtgebiet eine deutlich größere Fläche einnimmt als bisher angenommen wurde und vielteiliger sowie funktional gegliedert ist. Dieses erste stichpunktartige Ergebnis zeigt das Potential der Lipidanalysen, frühere Landnutzung zu rekonstruieren, beispielsweise Viehhaltung von acker- oder gartenb...
Between 2000 and 2005 archaeologists and students of the Institute of Archaeology, Mongolian Acad... more Between 2000 and 2005 archaeologists and students of the Institute of Archaeology, Mongolian Academy of Sciences, and the Department of Pre and Early Historical Archaeology, University of Bonn, excavated parts of a craftsmen quarter in the center of the old Mongolian capital Karakorum (Fig. 1) where — according to William of Rubruck, a Franciscan monk, who stayed there several months during spring 1254 (cf. Rubruck/Jackson 1990) — a Chinese population lived and worked in the 13 th century CE. The excavations in the center of the first capital of the Mongol Empire were carried out within the Mongolian–German Karakorum Expedition with the goal in the first instance of answering questions concerning the founding, the duration of settlement and the end of occupation of the entire town. In addition, interest focused on the profession and occupation of the people living in the urban center (Bemmann et al. 2010).
ABSTRACT This paper is based on data sets acquired by a fast and efficient ground-based measureme... more ABSTRACT This paper is based on data sets acquired by a fast and efficient ground-based measurement system, which is based on superconducting quantum interference device technology and ensures geo-magnetic mapping of large areas. The local variations (gradients) of the Earth's magnetic field are represented in so-called magnetograms, which typically include a large number of magnetic anomalies with different appearance and shape. Here, elongated anomalies are investigated, which are explainable by a polyhedral source body. These underground structures can be represented by a cross section that is approximately uniform along the main strike extent of the source. After introducing the measurement system, a source description model is developed theoretically and in the following adapted to practical problems. In order to illustrate the utility of this kind of minimization-based inversion and to validate the produced results, an example of archaeological measurements in Mongolia is shown. Results of the field measurements are used for inversion toward a description of possible subsoil situation. Finally, an excavation shows the accuracy of the results.
IEEE Transactions on Applied Superconductivity, 2013
ABSTRACT In Europe, the FLUXONICS Foundry develops fabrication processes and design kits for supe... more ABSTRACT In Europe, the FLUXONICS Foundry develops fabrication processes and design kits for superconductor digital and mixed-signal circuits. We describe the implementation of the “European Roadmap for Superconductor Electronics” into the recent foundry process for superconductor digital electronics. Following the hierarchical cell-based design strategy, we developed a design kit with basic cells. We present experimental results of the process quality, the verified operation margins of the library cells, and the results of low- and high-speed investigations of test circuits. The process is suitable for the integration of complex digital and mixed-signal circuits for smart multichannel superconductor sensor applications with a digital interface.
Mit großer Verwunderung haben wir den Beitrag von Wolf D. Pecher zur Kenntnis genommen. Der Text ... more Mit großer Verwunderung haben wir den Beitrag von Wolf D. Pecher zur Kenntnis genommen. Der Text missachtet aus unserer Sicht grundlegende wissenschaftliche und journalistische Standards.
We developed different types of thin film high temperature superconductor (high-T,) DC-SQUID magn... more We developed different types of thin film high temperature superconductor (high-T,) DC-SQUID magnetometers and gradiometers for application in a nondestructive testing system. We used these sensors in a liquid nitrogen dewar mounted above a computer controlled x-y table within a compact p-metal shielded chamber. The planar galvanically cou- pled gradiometers based on step-edge or bicrystal Josephson junctions were investigated in shielded and unshielded environment. We discuss the influence of junction type and SQUID parameters depending on the device geometry on the sensitivity of our complete testing system. Our interest is focused in particular on the noise properties and magnetic field resolution at 77 K. Measurements of ac and dc current distributions will be shown as well as measurements of magnetic moments of different samples. The quick development of low noise high-Tc DC-SQUIDS and their application in magnetometers and gradiometers make it possible to use these systems als...
Wetland environments, with their excellent conservation conditions, provide geoarchaeological arc... more Wetland environments, with their excellent conservation conditions, provide geoarchaeological archives of past human activities. However, the subsurface soil is difficult to access due to high groundwater tables, unstable sediments, and the high cost of excavation. In this study, we present a ground-based non- and minimal-invasive prospection concept adapted to the conditions of wetlands. We investigated the Fossa Carolina in South Germany, a canal that was intended in 792/793 AD by Charlemagne to bridge the Central European Watershed. Although the resulting Carolingian banks and the fairway with wooden revetments are very imposing, archaeological traces of off-site construction activities have not been identified hitherto. Based on a geophysically surveyed intensive linear magnetic anomaly parallel to the Carolingian canal, we aimed to prove potential off-site traces of Carolingian construction activities. In this context, we built up a high-resolution cross-section using highly de...
Uploads
Papers by Sven Linzen