134 research outputs found

    Supply Chain Control Principles in Local Food Production: A Norwegian Case Study

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    Based on an analysis of the supply chain of four producers of local specialty foods, we explore how planning and control principles can be applied to align supply chain capabilities and market requirements. It has been shown that local food struggles with market access, and that the supply chain is one of the obstacles preventing local food producers from gaining a solid market position. We identify a number of features of the local food chain, analyse the obstacles and develop generic designs and control principles for local food producers

    Sustainable engineering master module - Insights from three cohorts of European engineering team

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    Mobility and transnational migration are current social developments among the population of the European Union. These developments in both society-at-large and companies, linked to the challenges of sustainability, lead to new requirements for working in the European Union. Teaching and learning in higher education needs to adapt to these requirements. As a result, new and innovative teaching and learning practices in higher education should provide competencies for transnational teamwork in the curriculum of tomorrow's engineers in order to ensure their competitiveness in the job market. A transnational project-oriented teaching and learning framework, which provides the future key competencies for young engineers was implemented in the course European Engineering Team (EET). Engineering students from four countries participated in a new project-based course that focused on the development of innovative and sustainable products and opportunities. The goal of this paper is to present results and lessons learnt from three cohorts of EET

    Results from 730 kg days of the CRESST-II Dark Matter Search

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    The CRESST-II cryogenic Dark Matter search, aiming at detection of WIMPs via elastic scattering off nuclei in CaWO4_4 crystals, completed 730 kg days of data taking in 2011. We present the data collected with eight detector modules, each with a two-channel readout; one for a phonon signal and the other for coincidently produced scintillation light. The former provides a precise measure of the energy deposited by an interaction, and the ratio of scintillation light to deposited energy can be used to discriminate different types of interacting particles and thus to distinguish possible signal events from the dominant backgrounds. Sixty-seven events are found in the acceptance region where a WIMP signal in the form of low energy nuclear recoils would be expected. We estimate background contributions to this observation from four sources: 1) "leakage" from the e/\gamma-band 2) "leakage" from the \alpha-particle band 3) neutrons and 4) Pb-206 recoils from Po-210 decay. Using a maximum likelihood analysis, we find, at a high statistical significance, that these sources alone are not sufficient to explain the data. The addition of a signal due to scattering of relatively light WIMPs could account for this discrepancy, and we determine the associated WIMP parameters.Comment: 17 pages, 13 figure

    The CRESST II Dark Matter Search

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    Direct Dark Matter detection with cryodetectors is briefly discussed, with particular mention of the possibility of the identification of the recoil nucleus. Preliminary results from the CREEST II Dark Matter search, with 730 kg-days of data, are presented. Major backgrounds and methods of identifying and dealing with them are indicated.Comment: Talk at DSU workshop, ITP Beijing, Oct. 2011. 9 figures, 2 table

    Dark-Photon Search using Data from CRESST-II Phase 2

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    Identifying the nature and origin of dark matter is one of the major challenges for modern astro and particle physics. Direct dark-matter searches aim at an observation of dark-matter particles interacting within detectors. The focus of several such searches is on interactions with nuclei as provided e.g. by Weakly Interacting Massive Particles. However, there is a variety of dark-matter candidates favoring interactions with electrons rather than with nuclei. One example are dark photons, i.e., long-lived vector particles with a kinetic mixing to standard-model photons. In this work we present constraints on this kinetic mixing based on data from CRESST-II Phase 2 corresponding to an exposure before cuts of 52\,kg-days. These constraints improve the existing ones for dark-photon masses between 0.3 and 0.7\,keV/c2^2.Comment: submitted EPJ

    Results on light dark matter particles with a low-threshold CRESST-II detector

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    The CRESST-II experiment uses cryogenic detectors to search for nuclear recoil events induced by the elastic scattering of dark matter particles in CaWO4_4 crystals. Given the low energy threshold of our detectors in combination with light target nuclei, low mass dark matter particles can be probed with high sensitivity. In this letter we present the results from data of a single detector module corresponding to 52 kg live days. A blind analysis is carried out. With an energy threshold for nuclear recoils of 307 eV we substantially enhance the sensitivity for light dark matter. Thereby, we extend the reach of direct dark matter experiments to the sub-region and demonstrate that the energy threshold is the key parameter in the search for low mass dark matter particles.Comment: 8 pages, 8 figure

    A detector module with highly efficient surface-alpha event rejection operated in CRESST-II Phase 2

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    The cryogenic dark matter experiment CRESST-II aims at the direct detection of WIMPs via elastic scattering off nuclei in scintillating CaWO4_4 crystals. We present a new, highly improved, detector design installed in the current run of CRESST-II Phase 2 with an efficient active rejection of surface-alpha backgrounds. Using CaWO4_4 sticks instead of metal clamps to hold the target crystal, a detector housing with fully-scintillating inner surface could be realized. The presented detector (TUM40) provides an excellent threshold of ∼ 0.60 {\sim}\,0.60\,keV and a resolution of σ ≈ 0.090\sigma\,{\approx}\,0.090 keV (at 2.60 \,keV). With significantly reduced background levels, TUM40 sets stringent limits on the spin-independent WIMP-nucleon scattering cross section and probes a new region of parameter space for WIMP masses below 3 \,GeV/c2^2. In this paper, we discuss the novel detector design and the surface-alpha event rejection in detail.Comment: 9 pages, 6 figure
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