LTP: Laboratory for Particle Physics
Scientific Highlights and News
POLAR detector developed at the PSI flies into orbit with a Chinese space mission
Researchers working with Wojciech Hajdas at the Paul Scherrer Institute PSI have developed a detector called POLAR. This instrument is expected to search out and investigate so-called gamma ray bursts coming from the depths of the universe. Gamma ray bursts are eruptions of high-energy light that despite being extremely strong remain, up to now, only poorly understood.
Muon polarization in the MEG experiment: predictions and measurements
The MEG experiment makes use of one of the world’s most intense low energy muon beams, in order to search for the lepton flavour violating process μ+→e+γ . We determined the residual beam polarization at the thin stopping target, by measuring the asymmetry of the angular distribution of Michel decay positrons as a function of energy. The initial muon beam polarization at the production is predicted to be Pμ=−1Pμ=−1 by the Standard Model (SM) with massless neutrinos.
Rate of Molecular Transfer of Allyl Alcohol across an AOT Surfactant Layer Using Muon Spin Spectroscopy
The transfer rate of a probe molecule across the interfacial layer of a water-in-oil (w/o) microemulsion was investigated using a combination of transverse field muon spin rotation (TF-μSR), avoided level crossing muon spin resonance (ALC-μSR), and Monte Carlo simulations. Reverse micro-emulsions consist of nanometer-sized water droplets dispersed in an apolar solvent separated by a surfactant monolayer.
Observation of Gravitationally Induced Vertical Striation of Polarized Ultracold Neutrons by Spin-Echo Spectroscopy
We describe a spin-echo method for ultracold neutrons (UCNs) confined in a precession chamber and exposed to a |B0| = 1μT magnetic field. We have demonstrated that the analysis of UCN spin-echo resonance signals in combination with knowledge of the ambient magnetic field provides an excellent method by which to reconstruct the energy spectrum of a confined ensemble of neutrons.
Constraining interactions mediated by axion-like particles with ultracold neutrons
We report a new limit on a possible short range spin-dependent interaction from the precise measurement of the ratio of Larmor precession frequencies of stored ultracold neutrons and 199Hg atoms confined in the same volume. The measurement was performed in a ∼1μT vertical magnetic holding field with the apparatus searching for a permanent electric dipole moment of the neutron at the Paul Scherrer Institute.