EXAMPLE AMO PROJECT DESCRIPTIONS
Atomic, Molecular, Optical, and Plasma Physics
Two medium energy ion accelerators are housed on campus for the study of both ion - atom collisions and atomic spectroscopy. The larger of the two is a 30- to 330-kV, positive ion, multi-user facility (THIA). It is equipped with a universal ion source capable of producing low charge-state ions of virtually any element. Two faculty members, including the PI are primarily associated with this machine and several other mentors have collaborated in its use. THIA has 3 experimental stations associated with the beam line one for beam foil spectroscopy, the second line is used for doping or ion implantation and the third one is set up ion-gas collision studies. To date, over 37 undergraduate students (24 REU students) have participated in research on these beam lines.
Theoretical atomic physics faculty in this department is studying both atomic structure, some of these studies confirm measurements with THIA, and atomic collision systems. Structure calculations use a variety of relativistic and non-relativistic programs for computing atomic wave- functions for multi-electron atoms and ions. Areas of research include: Bose-Einstein Condensation (BEC), highly excited molecular roto-vibrational spectra, quantum optics, multiphoton processes, photoionization, systematics of spectra of highly-ionized atoms, core-, and multiply-excited atomic states, and inter-combination lines. We have one fellow of the APS in this area.Highlighted project: Title: Lifetimes, Oscillator Strengths, and Branching Fractions for Ultraviolet Transitions Mentors: Profs. S. R. Federman, R. Irving,
Decay curve λ1822 for a beam energy of 205keVwith REU student Furman.
S. Cheng, D. Ellis, graduate student R. Khayat Description: Nucleosynthesis in space leads to the formation of many elements. Abundances of atoms and molecules residing in space environments are derived from spectroscopic measurements revealing absorption and emission lines. Transition probabilities, branching fractions among channels, and oscillator strengths (a conversion factor) are needed to transform the amount of absorption or emission into abundances. The REU student researcher will be tasked with obtaining data which will allow the determination of the transition probabilities, branching fractions and oscillator strengths. This data will be obtained thru beam-foil spectroscopic techniques with the THIA to produce plots of radiative intensity as a function of a distance from the decaying atoms. The REU student will derive from the decay curves the lifetimes of excited levels, Students will also make measurements of intensity versus wavelength to reveal the lines associated with the decays of a level and allow us to derive branching fractions for each of the channels. Lifetimes will be transformed into transition probabilities and then oscillator strengths with the use of the branching fractions in order to deduce astrophysical abundances. Possible samples include neutral sulfur and chlorine as well as singly-ionized phosphorus.
Professional Development: The REU student will learn how to run the linear accelerator, THIA and its application in this case to produce a needed light source. The student will gain experience in interfacing detectors (e.g PMTs and channeltrons) via industrial standard hardware (e.g. Ortec Models) and software (e.g. LabVIEW) to make experimental measurements. The student with then learn how to analyze data through statistical studies to estimate the uncertainty of an experimental measurement.
Other projects: “Spin-forbidden transitions in the phosphorous isoelectronic sequence.” (Profs. R. Irving, D. Ellis); Student will carry out Multi-configuration Hartree-Fock and Dirac-Hartree-Fock calculations of inter-combination line strengths involving the (3s2 3p3) configuration in P-like atomic ions for a wide range of nuclear charge Z. Results will be compared with existing experiments and with theoretical ideas about the expected Z-dependence. The half-filled p-shell gives rise to a rich array of levels with isoelectronic trends which reflect the changing interplay between correlations and relativity. Much of the work will consist of developing and applying essential graphical aides such as energy-level diagrams and isoelectronic plots.
“Characterization of X-ray emission during X-Pinch and/or Z-Pinch Plasmas”, (Profs. R. Irving, T. Kvale, and A. Covington at NTF); The goal of this experiment is to sample high energy photon emissions to determine the characteristics of the pulse created by an X-Pinch and/or Z-Pinch configurations at the Nevada Terawatt Facility (NTF). The NTF will provide participating REU students an opportunity to carry out hands-on plasma physics research on our unique plasma physics accelerators. These platforms include the 2 TW Zebra Z-pinch generator which can be coupled to the 100 TW Leopard Laser.