Welcome to the Low-Energy Muons (LEM)
Introduction to the Experiment
Rebuilt µE4 beam
Low-Energy µSR Workshop 1999
Low-Energy Muons Group.
Very slow, nearly 100% polarized, positive muons with a mean energy of
about 15 eV can be used as a source of a tertiary beam of tunable
energy between 0 eV and 30 keV.
This energy range corresponds to tunable implantation depths between
a fraction of a nanometer and a few hundred nanometers, thus allowing
the extension of the
µSR techniques to the study of
thin films, multi-layers, and surfaces.
Basic atomic processes like charge exchange,
energy loss and scattering in matter can be studied
at low energies. Comparing these measurements with
known proton or hydrogen data, mass effects
and velocity scaling of the corresponding cross
sections can be tested.
A beam of muonium (hydrogen-like bound state of a positive muon
and an electron) with low energy spread can be formed by passing
low-energy muons through thin foils or gas targets. The muonium atom is an
ideal system for precision
spectroscopy in order to test the validity of Quantum
Electrodynamics (or to measure fundamental constants like the
muon mass or the muon magnetic moment), since the leptonic constituents
of muonium behave as pointlike particles.
An Introduction to the Experiment
In our group we have developed the technique of moderating a
surface muon beam with an initial energy of about
4 MeV and nearly 100% polarization
to a tertiary beam of low energy (0 - 30 keV), polarized muons.
In the following a short overview of several components of the experiment
Complete overview of the experimental setup.
Generation of epithermal muons.
Transport system for low-energy muons.
LEM data acquisition.
µSR experiments with low-energy muons.
Geant4 simulation of the LEM setup