Publikationsrepositorium - Helmholtz-Zentrum Dresden-Rossendorf

The Helmholtz-Center Dresden - Rossendorf operates several user beamlines for materials research using positron-annihilation energy and lifetime spectroscopy. The superconducting electron linear accelerator ELBE drives several secondary beams including hard X-ray production from electron-bremsstrahlung, which serves as an intense source of positrons by means of pair production. The Mono-energetic Positron Source MePS [1] utilizes positrons with variable kinetic energies ranging from 0.5 to 18 keV for depth profiling of atomic defects and porosities on nm-scales in thin films. High timing resolutions (σt ≈100 ps) at high average event rates in excess of 105 s-1 and adjustable beam repetition rates allow performing high-throughput positron annihilation lifetime experiments. Acquiring an annihilation lifetime spectrum with 107 events takes about 80 s which paves the way to perform in-situ PALS experiments on dynamical defect evolution, migration and annealing [2,3,4].
We will present the actual status of the MePS facility and updates which are on the way. A recently constructed sample chamber will allow for fast and automated sample transfers, an increased sample temperature range (80 K to 800 K), and possibilities for sample illuminations with light sources (LED, Laser, and a broadband short arc Xe light source).
The facility is part of the ELBE Center for High-Power Radiation Sources which operates several secondary beam lines for international users.

The MePS facility has partly been funded by the Federal Ministry of Education and Research (BMBF) with the grant PosiAnalyse (05K2013). Trans-national access is available through the EU-Horizon project ReMADE for academic and industry.

[1] A. Wagner, et al., AIP Conf. Proc. 1970, 040003 (2018)
[2] L. Chiari, et al., Acta Mater. 219, 117264 (2021)
[3] M. Wenskat, et al., Sci. Rep. 10, 8300 (2020)
[4] M. Wenskat, et al., Phys. Rev. B 106, 094516 (2022)
[5] ReMADE, https://remade-project.eu/