4,242 research outputs found
Test beam Characterizations of 3D Silicon Pixel detectors
3D silicon detectors are characterized by cylindrical electrodes
perpendicular to the surface and penetrating into the bulk material in contrast
to standard Si detectors with planar electrodes on its top and bottom. This
geometry renders them particularly interesting to be used in environments where
standard silicon detectors have limitations, such as for example the radiation
environment expected in an LHC upgrade. For the first time, several 3D sensors
were assembled as hybrid pixel detectors using the ATLAS-pixel front-end chip
and readout electronics. Devices with different electrode configurations have
been characterized in a 100 GeV pion beam at the CERN SPS. Here we report
results on unirradiated devices with three 3D electrodes per 50 x 400 um2 pixel
area. Full charge collection is obtained already with comparatively low bias
voltages around 10 V. Spatial resolution with binary readout is obtained as
expected from the cell dimensions. Efficiencies of 95.9% +- 0.1 % for tracks
parallel to the electrodes and of 99.9% +- 0.1 % at 15 degrees are measured.
The homogeneity of the efficiency over the pixel area and charge sharing are
characterized.Comment: 5 pages, 7 figure
Magnetically asymmetric interfaces in a (LaMnO)/(SrMnO) superlattice due to structural asymmetries
Polarized neutron reflectivity measurements of a ferromagnetic
[(LaMnO)/(SrMnO)] superlattice reveal a modulated
magnetic structure with an enhanced magnetization at the interfaces where
LaMnO was deposited on SrMnO (LMO/SMO). However, the opposite
interfaces (SMO/LMO) are found to have a reduced ferromagnetic moment. The
magnetic asymmetry arises from the difference in lateral structural roughness
of the two interfaces observed via electron microscopy, with strong
ferromagnetism present at the interfaces that are atomically smooth over tens
of nanometers. This result demonstrates that atomic-scale roughness can
destabilize interfacial phases in complex oxide heterostructures.Comment: 5 pages, 4 figure
Magnetic Structure in Fe/Sm-Co Exchange Spring Bilayers with Intermixed Interfaces
The depth profile of the intrinsic magnetic properties in an Fe/Sm-Co bilayer
fabricated under nearly optimal spring-magnet conditions was determined by
complementary studies of polarized neutron reflectometry and micromagnetic
simulations. We found that at the Fe/Sm-Co interface the magnetic properties
change gradually at the length scale of 8 nm. In this intermixed interfacial
region, the saturation magnetization and magnetic anisotropy are lower and the
exchange stiffness is higher than values estimated from the model based on a
mixture of Fe and Sm-Co phases. Therefore, the intermixed interface yields
superior exchange coupling between the Fe and Sm-Co layers, but at the cost of
average magnetization.Comment: 16 pages, 6 figures and 1 tabl
The global rise of private art museums a literature review
In this state-of-the-art article, we review studies of the highly controversial, global rise of private art museums as a new organizational form within art fields. Given that current studies are scattered across different disciplines like sociology, museum studies, economics and anthropology, a systematic engagement with theoretical and methodological issues is difficult. This paper compiles and discusses these studies, identifying key themes, controversies as well as areas of consensus. We organize our review according to eight key themes: 1. (non)-existent definitions of private museums; 2. their historical roots; 3. geographical dimensions; 4. the life course of private museums; 5. their relation to public museums; 6. the involvement of the government; 7. private museums as actors in the art field, and 8. the implications for the (re)production of social inequalities. We conclude by reflecting on the most significant gaps in the literature and formulate a research agenda that can guide us to a more systematic inquiry of the private museum phenomenon
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