Grants and Contracts Details
Description
Two experiments on He ionization are proposed that build on the s~vrk done during
the present grant period.
The first, motivated by major disagreements between theory and experiment reported
in the literature, will measure out-of-scattering-plane (e,2e) angular distributions at a range
of incident electron energies, for a full 3600, using a special geometry that allows out-of-
plane conditions to be combined with the binary peak in a single measurement. Data
will be taken in the energy region of He autoionizing states, both on and off resonance.
The results will be compared to state-of-the-art first and second order calculations. Of
particular interest are the experiments at low incident energy where the out-of-plane region
is expected to have enhanced intensity. This experiment will use an (e,2e) apparatus
modified during the present grant period to allow the electron gun to move on the surface
of a (mathematical) cone. We will continue our successful collaboration on this experiment
with Klaus Bartschat's theory group at Drake University, Iowa.
The second experiment will investigate electron-impact helium autoionization in the
presence of a laser field. Preliminary experiments carried out during the present grant
period have seen an enhancement of the autoionization peaks when the laser beam is
present. These experiments will be continued to confirm this result. Ejected electron
spectra will be measured at a range of angles with respect to the laser polarization. In
addition to measuring changes in autoionization intensity and lineshape due to the laser
field, we will look for "sidebands" separated from the normal autoionization peaks by
energies equal to integral numbers of the photon energy. The advantage of this type
of experiment is that it isolates the photon-target interaction from the photon-projectile
interaction; there is at present poor agreement between experiments that involve both
types of interaction and theories that emphasize the photon-projectile interaction. These
experiments use one of the P1's apparatuses that has been extensively modified during the
present grant period and has been interfaced with one of the Co-PT's Nd:YAG lasers.
limui4erim acts resulting from the Proposed Research
The research will involve both undergraduate and graduate students at the University
of Kentucky. Undergraduates will work on a project such as data analysis. The project
will provide dissertation material for at least two graduate students. Students acquire
skills in lasers, electronics, vacuum systems, and computer programming, networking, and
interfacing with experiments. They present their work at national and international con-
ferences.
Status | Finished |
---|---|
Effective start/end date | 8/1/09 → 7/31/15 |
Funding
- National Science Foundation: $340,000.00
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