### Session Poster: Experimental Physics Research

Chair: Paul Oxley, Holy Cross College
Room: Holy Cross College Ballroom

 Poster.00001: Apparatus For Laser Excitation of Lithium Atoms. James Daly , Suzy Flaherty , Paul Oxley We have constructed and tested a vacuum system and a simple lithium oven. Lithium atoms from this oven will be excited to high principal quantum number by a combination of three lasers. We have also built and tested the hardware needed to operate the first of these lasers. In the future we will study charge transfer collisions between excited lithium atoms and ions to gain a better understanding of the physical properties of fusion, astrophysical, and other types of plasmas. Our vacuum system is assembled from standard conflat vacuum parts and from parts designed and built at Holy Cross. The vacuum environment is maintained by a diffusion pump in conjunction with a cold water trap to prevent pump oil migrating into our vacuum system. Our lithium oven consists of a small steel tube filled with lithium and mounted inside our vacuum system. The oven is heated by high temperature heater tapes. We have reached oven temperatures of over 600C which provides a sufficiently intense Li beam for our needs. The laser used in the first excitation step of lithium is a diode laser operating at 671nm. We have assembled the mechanical structure used to mount the diode laser and collimate its light output. Commercial electronics control the laser diode current and its temperature. Initial tests of the properties of the laser have been made. Poster.00002: Cation Site Occupancy of Fine Magnesium Ferrite Powders Having Enhanced Neel Temperatures Aaron Oehlschlaeger , Martin Snow , Steven Oliver , Vincent Harris , C.N. Chinnasamy , H. Kaileen , S.D. Yoon , A. Yang , C. Vittoria , S. Mukerjee , M.D. Schulz , E.E. Carpenter Magnesium ferrite powders having mean diameters of from 4 nm to 50 nm were produced by a modified coprecipitation method and then measured by structural and magnetic probes. All samples were found as phase-pure MnFe$_{2}$O$_{4}$ through XRD results, with particle size distributions being determined through TEM measurements. High-field SQUID magnetometer measurements found the Neel temperature increased from 300$^{0}$C to 380$^{0}$C with increasing mean particle size, in comparison to the Neel temperature of bulk MnFe$_{2}$O$_{4}$ of 300$^{0}$C. Since the magnetization behavior of spinel ferrites is sensitive to the magnetic interactions between iron cations occupying octahedral and tetrahedral sites in the spinel structure, it is anticipated that the cation distribution may be affected by the reaction kinetics involved in particle formation. To test this, extended x-ray absorption fine structure (EXAFS) measurements were taken on the powders and representative bulk samples. This poster will show that the EXAFS data does show a distinct difference in site occupancy between the powder and bulk samples, although the trend between samples may not be as distinct. Poster.00003: Fitting Mock X-ray Observations of Simulated Galaxy Clusters Andrew Pawl We investigate statistically whether fitting the actual X-ray spectrum of a galaxy cluster to a single component, unbroadened X-ray spectrum gives a reliable idea of the temperature and metallicity of the cluster. Eighteen different fitting schemes are performed using Xspec on 198 simulated galaxy clusters and their results compared to the emission-measure weighted temperature and metallicity profiles recovered from the simulations. Poster.00004: UV Induced Degradation of Polycarbonate-Based Lens Materials and Implications for the Heath Care Field J.R. Harkay , Jerry Henry Experimental research is being carried out at Keene State at the undergraduate level that utilizes facilities in both physics and chemistry to study the effects of mono- and polychromatic UV radiation from various sources, including a Deuterium lamp, a solarization unit (at Polyonics, a local industry), and the Sun, to study the photodegradation of polycarbonate-based lens materials used to produce eyewear. Literature in the field of optometry and ophthalmology indicates a correlation between exposure to the UVB band of natural sunlight and the onset of cataract formation, as well as other eye disorders. The public is usually advised that plastic eyeglass lenses will provide protection from this damaging radiation. It is well known that polycarbonate plastic yellows'' when exposed to intense sunlight and, particularly, UV light$^{1,2}$, either via photo-Fries rearrangement or by a photooxidative process, forming polyconjugated systems and is an industrial concern primarily for cosmetic reasons. We have preliminary data, however, that indicates that the yellowing'' is an indication of a more sinister problem in the case of eyeglasses in that it is accompanied by an increase in transmissivity in the UVB band where the wearer expects and needs protection. Our group includes a local optometrist who will share results with peers in his field. [1] A. Andrady, J. Polymer Sci., \textbf{42, }1991 [2] E. P. Gorelov, Inst. Khim. Fiz., Russian Federation Poster.00005: Laboratory Measurement of 50-300eV X rays from Collisions of S, Ne ions with molecules of Cometary Interest. Kenneth Miller , Christopher Verzani , Anne Wrigley , Quentin Kessel , Winthrop Smith , Steve Smith , Sabbir Hossain , Ara Chutjian Approximately 90 percent of the observed cometary x rays have energies in the 50 -- 300 eV range. It is assumed these x rays may be the result of electron capture to excited states, similar to the explanation of the 250 -- 700 eV cometary x-ray lines being due to the transfer of electrons from cometary gases (CO, H$_{2}$O, etc.). The present data are consistent with this interpretation. We present here spectra obtained, using solar wind-type ions such as Ne$^{7+}$, Ne$^{8+}$, S$^{9+}$, and O$^{6+}$ from the JPL ECR ion source. Our spectra suggest that charge transfer to these highly-charged solar wind species contributes significantly to cometary x-ray spectra in the 50-300eV energy range.