The reduction of emission is a key goals for the aviation industry. One enabling technology to achieve this goal, could be the transition from conventional gas turbines to hybrid-electric drive trains. However, the requirements concerning weight and efficiency that come from applications like short range aircraft are significantly higher than what state-of-the-art technology can offer. A key technology that potentially allows to achieve the necessary power and volume densities for rotating electric machines is superconductivity. In this paper we present the concept of a high power density generator that matches the speed of typical airborne turbines in its power class. The design is based on studies that cover topology selection and further electromagnetic, HTS, thermal, structural and cryogenics aspects. All domains were analyzed by means of analytical sizing and 2D/3D FEA modeling. With the help of our digital twin that is a synthesis of these models, we can demonstrate for the first time that under realistic assumptions on material properties gravimetric power densities beyond 20 kW kg−1 can be achieved.
We investigated the potential of the energy resolving hybrid pixel detector Timepix contacted to a CdTe sensor layer for the search for the neutrinoless double-beta decay ofCd. We found that a CdTe sensor layer with 3 mm thickness and 165 μm pixel pitch is optimal with respect to the effective Majorana neutrino mass (mββ) sensitivity. In simulations, we were able to demonstrate a possible reduction of the background level caused by single electrons by approximately 75% at a specific background rate of 10−3counts/(kg×keV×yr) at a detection efficiency reduction of about 23% with track analysis employing random decision forests. Exploitation of the imaging properties with track analysis leads to an improvement in sensitivity tomββby about 22%. After 5 years of measuring time, the sensitivity tomββof a 420 kg CdTe experiment (90%Cdenrichment) would be 59 meV on a 90% confidence level for a specific single-electron background rate of 10−3counts/(kg×keV×yr). Theα-particle background can be suppressed by at least about six orders of magnitude. The benefit of the hybrid pixel detector technology might be increased significantly if drift-time difference measurements would allow reconstruction of tracks in three dimensions.
During the last decades, multi-pixel detectors have been developed capable of registering single photons. The newly developed Hybrid Photon Detector camera has a remarkable property that it has not only spatial but also temporal resolution. In this work, we use this device for the detection of non-classical light from spontaneous parametric down-conversion and use two-photon correlations for the absolute calibration of its quantum efficiency.References and links
In the past decades the search for neutrinoless double beta decay has driven many developments in all kind of detector technology. A new branch in this field are highly-pixelated semiconductor detectors-such as the CdTe-Timepix detectors. It comprises a cadmium-telluride sensor of 14 mm × 14 mm × 1 mm size with an ASIC which has 256 × 256 pixel of 55 µm pixel pitch and can be used to obtain either spectroscopic or timing information in every pixel. In regular operation it can provide a two dimensional projection of particle trajectories; however, three dimensional trajectories are desirable for neutrinoless double beta decay search and other applications. In this paper we present a method to obtain such trajectories. The method was developed and tested with simulations that assume some minor modifications to the Timepix ASIC. Also, we were able to test the method experimentally and in the best case achieved a position resolution of about 63 µm for electrons with an energy of 4.4 GeV.
Many different experiments are being developed to explore the existence of the neutrinoless double beta decay (0νββ) since it would imply fundamental consequences for particle physics. In this work we present results on the evaluation of Timepix detectors with cadmium-telluride sensor material to search for 0νββ in 116 Cd. This work was carried out with the COBRA collaboration and the Medipix collaboration. Due to the relatively small pixel dimension of 110 × 110 × 1000 µm 3 the energy deposited by particles typically extends over several detector pixels leading to a track in the pixel matrix. We investigated the separation power regarding different event-types like α-particles, atmospheric muons, single electrons and electron-positron pairs produced at a single vertex. We achieved excellent classification power for α-particles and muons. In addition, we achieved good separation power between single electron and electron-positron pair production events. These separation abilities indicate a very good background reduction for the 0νββ search. Further, in order to distinguish between 2νββ and 0νββ, the energy resolution is of particular importance. We carried out simulations which demonstrate that an energy resolution of 0.43 % is achievable at the Q-value for 0νββ of 116 Cd at 2.814 MeV. We measured an energy resolution of 1.6 % at a nominal energy of 1589 keV for electron-positron tracks which is about two times worse that predicted by our simulations. This deviation is probably due to the problem of detector calibration at energies above 122 keV which is discussed in this paper as well. a
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