Laser excitation of the 1-2 transition in singly-ionized helium.

Laser spectroscopy of atomic hydrogen and hydrogen-like atoms is a powerful tool for tests of fundamental physics. The 1-2 transition of hydrogen in particular is a cornerstone for stringent Quantum Electrodynamics (QED) tests and for an accurate determination of the Rydberg constant. We report laser excitation of the 1-2 transition in singly-ionized helium (He), a hydrogen-like ion with much higher sensitivity to QED than hydrogen itself.

Measuring the α-particle charge radius with muonic helium-4 ions.

The energy levels of hydrogen-like atomic systems can be calculated with great precision. Starting from their quantum mechanical solution, they have been refined over the years to include the electron spin, the relativistic and quantum field effects, and tiny energy shifts related to the complex structure of the nucleus. These energy shifts caused by the nuclear structure are vastly magnified in hydrogen-like systems formed by a negative muon and a nucleus, so spectroscopy of these muonic ions can be used to investigate the nuclear structure with high precision.

Improved x-ray detection and particle identification with avalanche photodiodes.

Avalanche photodiodes are commonly used as detectors for low energy x-rays. In this work, we report on a fitting technique used to account for different detector responses resulting from photoabsorption in the various avalanche photodiode layers. The use of this technique results in an improvement of the energy resolution at 8.

Multipass laser cavity for efficient transverse illumination of an elongated volume.

A multipass laser cavity is presented which can be used to illuminate an elongated volume from a transverse direction. The illuminated volume can also have a very large transverse cross section. Convenient access to the illuminated volume is granted.

Anle138b: a novel oligomer modulator for disease-modifying therapy of neurodegenerative diseases such as prion and Parkinson's disease.

In neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD) and prion diseases, deposits of aggregated disease-specific proteins are found. Oligomeric aggregates are presumed to be the key neurotoxic agent. Here we describe the novel oligomer modulator anle138b [3-(1,3-benzodioxol-5-yl)-5-(3-bromophenyl)-1H-pyrazole], an aggregation inhibitor we developed based on a systematic high-throughput screening campaign combined with medicinal chemistry optimization.