Fundamental Research

PSI research facilities reveal magnetic crossover

Spins tick-tock like a grandfather clock and then stop. Thanks to complementary experiments at the Swiss Muon Source SµS, Swiss Spallation Neutron Source SINQ and the Swiss Light Source SLS, researchers led by the University of Geneva have discovered this coveted characteristic, known as magnetic crossover, hidden within the magnetic landscape of an exotic layered material. Magnetic crossover means tuneability and with it promise for spin-based electronics.

Monte-Carlo calculated detector response functions to unfold radiative neutron capture spectra

A complete set of detector response functions, i.e. the gamma spectra corresponding to incremental gamma-ray energies up to 12 MeV, were obtained for the Budapest PGAA facility by geant4 Monte-Carlo simulations and were used to unfold the experimental prompt-gamma spectra, for use in nuclear physics.

The unfolding successfully removed the continuous Compton-background and the escape peaks related to a full-energy peak but preserved the shape and area of the full-energy peak itself.

Structuring of nanoparticle suspension probed by neutron reflectivity

The behaviour of colloidal particles at water-solid interfaces is relevant in material science, food processing, medicine and environmental engineering. A team from the University of Geneva with researchers from the Budapest Neutron Centre used neutron reflectivity to study colloidal silica nanoparticle suspensions near the (negatively) like-charged native-oxide-covered surface of Si. Intriguingly, the nanospheres develop a self-organised damped, oscillatory concentration profile normal to the interface, as demonstrated in the figure.