Summer 2005

In the summer of 2005, a total of ten students participated in summer research in the Physics Department. Two students (Heidi Brooks and Jenny Welch) were partially supported by carryover NSF REU funds from the summer of 2004, with the balance of their support coming from DOE. Seven more undergraduate students were supported by DOE and DoD funds, and one high school student volunteered. Otside the physics department, another eighteen students, mostly in Biological Sciences, were supported by NSF EPCoR and by the BRIN program. In total, twenty-eight students participated, supervised by sixteen mentors, in five different departments, from UNLV, three other universities, and one high school.

Heidi Brooks (Reed College) worked with Prof. Andrew Cornelius in the summer of 2005 to explore spin-relaxation processes in diluted holmium titanate (Ho₂Ti₂O₇). Magnetization measurements (AC and DC) were made using the Physical Properties Measurement System (PPMS) on various dilutions of Holmium Titanate (Ho_xLa₂-xTi₂O₇) where x = 1.9, 1.6, and 0.3, and Ho_xY₂-xTi₂O₇ where x = 0.2, 0.5, and 0.7), a recently discovered topologically frustrated ferromagnet. By varying the temperature within the system (from 50 K to 0.36 K), the strength of the superimposed magnetic field and the frequency at which the field changes its direction (from 10 Hz to 10 kHz), useful information was obtained about the nature of the spin relaxation processes that take place on an atomic level with the compounds. The results show that these processes resemble activated behavior over a certain range of frequencies, from which it was possible to calculate the activation barriers and relaxation times. In addition various unexplained patterns were found in the data which could possibly be attributed to an activation barrier dependent on frequency.

Jenny Welch (Cal Poly Pomona) worked with Prof. John Farley to study the corrosion of steel by molten metal. This materials question is of great interest to the Department of Energy because it is key to proposal plans to transmute radioactive waste. Welch investigated samples of steel that had been exposed to a eutectic mixture of lead and bismuth at elevated temperatures. These steel samples had varying amounts of silicon, which has been found to improve the corrosion resistance. She used the Scanning Electron Microscope, the microprobe, and other materials characterization tools, probing the role of silicon in the corrosion process. Her work was incorporated into a manuscript submitted to the Journal of Nuclear Materials: "Spectroscopic and microscopic study of the corrosion of iron-silicon steel by lead-bismuth eutectic (LBE) at elevated temperatures", Allen L. Johnson, Eric P. Loewen, Thao T. Ho, Dan Koury, Brian Hosterman, Umar Younas, Jenny Welch*, and John W. Farley, J. Nucl. Mater. (submitted).

Last updated Dec. 30, 2005