The buffer-gas trap (BGT) is a well-established method for accumulating a steady-state stream of positrons into dense, cool, single-component clouds/plasmas, which can in turn be used to generate pulses or beams tailored to the application at hand [1]. BGTs are regularly employed in the creation of anti-atoms, the generation of positronium, studies of atomic and molecular interactions with...
We apply Positron Annihilation Spectroscopy (PAS) to monitor the environmental degradation of ZnO/CIGS and perovskite thin film solar cells. Furthermore, yttrium oxy-hydride thin films are studied in view of their special photochromic properties, with the aim to elucidate the nature of vacancies in YOxHy and their evolution under in-situ UV illumination.
Our PALS study of as-deposited...
A Positron-Electron eXperiment (APEX) aims to produce magnetically confined, low temperature positron-electron plasma to test predictions that such a system with equal mass but oppositely charged species, in contrast to most laboratory and astrophysical plasma, is remarkably stable and exhibits other unique plasma characteristics. The magnetic trap will consist of a levitated superconducting...
We are focused on the long term operation of nuclear reactors, which is one of the most discussed challenges in nuclear power engineering. The radiation degradation of nuclear materials limits the operational lifetime of all nuclear installations or at least decreases its safety margin. This paper is focused on experimental simulation and evaluation of materials via hydrogen ion implantation...
The neutron induced positron source NEPOMUC at FRM II/MLZ provides the world’s highest intensity of 10^9 moderated positrons per second. The primary energy of the positrn beam is set to 1 keV. For the vast majority of user experiments, however, the brightness enhanced remoderated positron beam with a typical energy of 20 eV (~5x10^7 positrons per second) is used.
Within this contribution...
I will review recent studies done thanks complementary and basic measurements carried out with NEPOMUC apparatuses. Depth resolved measurements with Positron annihilation lifetime spectroscopy (PALS), Doppler broadening spectroscopy (DBS) and coincidence Doppler broadening spectroscopy (CDBS) were performed in thin films.
Transport properties of light gas molecules were measured in...
The capabilities of the Coincident Doppler-Broadening Spectrometer at the Neutron-induced Positron Source Munich (NEPOMUC) will be presented. In addition an overwiew of planned expansions will be given.
Two beam modes are available: standard operations provide a beam spot of $> 300\ \mu\textrm{m}$ (FWHM) and micro beam for scanning with a reduced diameter of $33\ \mu$m (FWHM). Mearsurements...
The pulsed low energy positron beam PLEPS is a user facility for defect-profiling with positron lifetime measurements using a monochromatic pulsed beam of variable implantation energy at the intense positron source NEPOMUC at the MLZ in Garching.
Typical applications of PLEPS comprise the defect identification in thin layers and layered structures of semiconductors and insulators, the...
The neutron-induced positron source Munich (NEPOMUC) provides a monochromatic low-energy positron beam with an intensity of > 1·109 e+/s and a diameter of ≈ 10 mm. To create a small beam focus or sharp positron pulses of 100 ps the beam brightness needs to be enhanced by re-moderation.
Based on the experiences with the remoderator setup, we redesigned and extended the...
Gallium nitride is a direct wide-bandgap semiconductor and an ideal material for power electronics. In device structure fabrication, controlled impurity doping in a selective area is essential. Ion implantation is the most commonly used technique to control carrier concentrations. A drawback of ion implantation is the introduction of defects. Thus, controlling damage during and after ion...
