The Atomic Physics
Group
Visiting
and Other Faculty: Safronova
Emeritus
Faculty: Johnson
Experimental
Program
The
experimental atomic physics program at Notre Dame is directed toward
the study of the structure, excitation, and de-excitation characteristics
of atoms and ions. This work stimulates advances in the theoretical
understanding of atomic systems at the most fundamental level, where
relativistic and field-theoretic aspects of the atoms become important.
An
experimental laser spectroscopy program focuses on precision measurements
of transition amplitudes and energies. These measurements are of
interest to the study of parity nonconservation effects in atoms
which is motivated by the study of weak interactions and are part
of a low energy test of the standard model. High-resolution spectroscopic
techniques are also used in other applications. This program involves
the use of tunable dye lasers and diode lasers.
Highly
stripped heavy-ion beams of 10-100 MeV energy are produced at the
accelerator facilities of the Nuclear Structure Laboratory. Experiments
are also performed at other off-site heavy-ion accelerators. Present
investigations concentrate on the precision atomic spectroscopy
of highly ionized atoms and the measurement of lifetimes of selected
atomic states in these ions. The spectroscopic measurements test
current relativistic and quantum electro-dynamic calculations of
atomic structure for few-electron ions. The lifetime results reflect
the effects of both electron correlations and relativistic contributions
in the de-excitation rates of excited atomic states. These data
are also important to the diagnostics and modeling of high-temperature
astrophysical and laboratory plasmas.
At
APAL, the Atomic Physics Accelerator Laboratory in the Nieuwland
Science Hall basement, fast heavy ions (up to 200 keV energies)
are used for Doppler-free laser studies of atomic hyperfine structures,
precision lifetime measurements, and other studies of atomic collisions
and structures.
Theoretical
Program
Notre Dame atomic theorists
work on problems at the interface of atomic and particle physics.
Recently, they have been involved in calculations of electron electric
dipole moment enhancement factors in heavy rare-earth ions in support
of experiments to detect time-reversal (T) violation. The atomic theory
group produced the most accurate available prediction of parity nonconserving
(PNC) amplitude in cesium, which, when combined with experiment, served
as a stringent test of the standard model. Systematic calculations
of the PNC amplitudes induced by the nuclear anapole moment have also
been carried out. Recently, the atomic theory group calculated isotope
shifts in ions of interest in the search for time-variation of the
fine-structure constant. Higher-order corrections to quantum field
theories for hydrogen, helium, and positronium are other subjects
of current investigations. In a different but related atomic theory
project, ab initio studies of transport properties of warm-dense plasmas
are underway.
A Tribute to Walter Johnson
Walter Johnson Symposium - Presentations and Conference Papers.
|
