arXiv subjects

D. Schaadt

Publications and source records attributed to D. Schaadt.

3 recordsLinked to original sources

arXiv2026

Microchannel plate detector development for ultraviolet astronomy

Observational data from the UV wavelength range is crucial to solve several astrophysical puzzles. Consequently, there are a number of upcoming UV missions from CubeSats up to the future flagship Habitable Worlds Observatory. Besides novel instrument concepts and improved coatings, advanced detectors are key for the success of these missions. The microchannel plate (MCP) detector technology offers a unique asset in the UV: the combination of single-photon counting and visible-blindness. The UV hardware group at the Institut f\"ur Astronomie und Astrophysik T\"ubingen (IAAT) develops a versatile MCP detector system that addresses the complete UV band. While a sealed-tube design is limited to wavelengths above 118\,nm, an open-face variant also covers the whole far- and extreme-UV. Both use the same readout: a coplanar cross-strip anode and FPGA-based electronics. In this contribution, we report on the status of the detector development, present the latest characterization results, and give an outlook on the mission prospects.

astro-ph.IM↗

arXiv2025

Progress towards a microchannel plate detector with AlGaN photocathode and cross-strip anode for ultraviolet astronomy

Microchannel plates (MCPs) were the driving detector technology for ultraviolet (UV) astronomy over many years, and still today MCP-based detectors are the baseline for several planned UV instruments. The development of advanced MCP detectors is ongoing and pursues the major goals of maximizing sensitivity, resolution, and lifetime, while at the same time decreasing weight, volume, and power consumption. Development efforts for an MCP-based detector system for the UV are running at IAAT at the University of T\"ubingen. In this publication, we present our latest results towards coating aluminum gallium nitride (AlGaN) photocathodes directly on MCPs, to improve quantum detection efficiency in the far- and extreme-UV. Furthermore, we report on the implementation of a non-iterative centroiding algorithm for our coplanar cross-strip anode directly in an FPGA.

astro-ph.IM↗

arXiv2009

Radius dependent shift of surface plasmon frequency in large metallic nanospheres: theory and experiment

Theoretical description of oscillations of electron liquid in large metallic nanospheres (with radius of few tens nm) is formulated within random-phase-approximation semiclassical scheme. Spectrum of plasmons is determined including both surface and volume type excitations. It is demonstrated that only surface plasmons of dipole type can be excited by homogeneous dynamical electric field. The Lorentz friction due to irradiation of electro-magnetic wave by plasmon oscillations is analyzed with respect to the sphere dimension. The resulting shift of resonance frequency turns out to be strongly sensitive to the sphere radius. The form of e-m response of the system of metallic nanospheres embedded in the dielectric medium is found. The theoretical predictions are verified by a measurement of extinction of light due to plasmon excitations in nanosphere colloidal water solutions, for Au and Ag metallic components with radius from 10 to 75 nm. Theoretical predictions and experiments clearly agree in the positions of surface plasmon resonances and in an emergence of the first volume plasmon resonance in the e-m response of the system for limiting big nanosphere radii, when dipole approximation is not exact.

cond-mat.mes-hall↗