- SourceAvailable from: Henrik Pedersen[Show abstract] [Hide abstract]
ABSTRACT: We present triethylboron (TEB) as a single-source precursor for chemical vapor deposition (CVD) of B x C thin films and study its gas phase chemistry under CVD conditions by quantum chemical calculations. A comprehensive thermochemical catalogue for the species of the gas phase chemistry of TEB is examined and found to be dominated by b-hydride eliminations of C 2 H 4 to yield BH 3. A complementary bimolecular reaction path based on H 2 assisted C 2 H 6 elimination to BH 3 is also significant at lower temperatures in the presence of hydrogen. Furthermore, we find a temperature window of 600–1000 1C for the deposition of X-ray amorphous B x C films with 2.5 r x r 4.5 from TEB. Films grown at temperatures below 600 1C contain high amounts of H, while temperatures above 1000 1C result in C-rich films. The film density and hardness are determined to be in the range of 2.40–2.65 g cm À3 and 29–39 GPa, respectively, within the determined temperature window.
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ABSTRACT: The European Spallation Source (ESS) in Lund, Sweden will become the world's leading neutron source for the study of materials. The instruments are being selected from conceptual proposals submitted by groups from around Europe. These instruments present numerous challenges for detector technology in the absence of the availability of Helium-3, which is the default choice for detectors for instruments built until today and due to the extreme rates expected across the ESS instrument suite. Additionally a new generation of source requires a new generation of detector technologies to fully exploit the opportunities that this source provides. The detectors will be sourced from partners across Europe through numerous in-kind arrangements; a process that is somewhat novel for the neutron scattering community. This contribution presents briefly the current status of detectors for the ESS, and outlines the timeline to completion. For a conjectured instrument suite based upon instruments recommended for construction, a recently updated snapshot of the current expected detector requirements is presented. A strategy outline as to how these requirements might be tackled by novel detector developments is shown. In terms of future developments for the neutron community, synergies should be sought with other disciples, as recognized by various recent initiatives in Europe, in the context of the fundamentally multi-disciplinary nature of detectors. This strategy has at its basis the in-kind and collaborative partnerships necessary to be able to produce optimally performant detectors that allow the ESS instruments to be world-leading. This foresees and encourages a high level of collaboration and interdependence at its core, and rather than each group being all-rounders in every technology, the further development of centres of excellence across Europe for particular technologies and niches.
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ABSTRACT: ESS server PDF download link http://eval.esss.lu.se/DocDB/0002/000274/014/TDR_online_ver_all.pdf ESS, the European Spallation Source, will be a major user facility at which researchers from academia and industry will investigate scientific questions using neutron beams. Neutron methods provide insights about the molecular building blocks of matter not available by other means. They are used for both basic and applied research. ESS will be a slow neutron source of unparallelled power and scientific performance. It will deliver its first protons to a solid, rotating tungsten target in 2019, which will in turn generate neutrons for delivery to an initial suite of seven neutron scattering research instruments. ESS will reach its full design specifications in 2025, with a suite of 22 research instruments. The publication of the Technical Design Report in 2013 represents an important milestone for the ESS project, marking its readiness to move forward with construction activities. This executive overview provides a brief summary of the key insights and findings of the Technical Design Report.
Conference Paper: Detectors for the European Spallation Source[Show abstract] [Hide abstract]
ABSTRACT: The European Spallation Source (ESS) in Lund, Sweden will become the world's leading neutron source for the study of materials by 2025. First neutrons will be produced in 2019. It will be a long pulse source, with an average beam power of 5 MW delivered to the target station. The pulse length will be 2.86 ms and the repetition rate 14 Hz. The ESS is presently in a design update phase, which ends in February 2013 with a Technical Design Report (TDR). Construction will subsequently start with the goal of bringing the first seven instruments into operation in 2019 at the same time as the source. The full baseline suite of 22 instruments will be brought online by 2025. These instruments present numerous challenges for detector technology in the absence of the availability of Helium-3, which is the default choice for detectors for instruments built until today. Additionally a new generation of source requires a new generation of detector technologies to fully exploit the opportunities that this source provides. This contribution presents briefly the current status of the ESS, and outlines the timeline to completion. The number of instruments and the framework for the decisions on which instruments should be built are shown. For a conjectured full instrument suite, which has been chosen for demonstration purposes for the TDR, a snapshot of the current expected detector requirements is presented. An outline as to how some of these requirements might be tackled is shown. Given that the delivery of the ESS TDR is only a few months away, this contribution reflects strongly the content of the TDR.