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Articles 1 - 16 of 16
Full-Text Articles in Physical Sciences and Mathematics
Veritas Very High Energy Observations Of The Distant Blazar 1es 0647+250, Margaret R. Molter, Jon Dumm, Lucy Fortson
Veritas Very High Energy Observations Of The Distant Blazar 1es 0647+250, Margaret R. Molter, Jon Dumm, Lucy Fortson
Macalester Journal of Physics and Astronomy
We perform an analysis of the long- and short-term variability of the very high energy (VHE; above 100 GeV) gamma-ray emission from the newly-detected distant blazar 1ES 0647+250. Both new and archival data from the VERITAS telescope were examined, and no strong evidence for integral flux variability on any timescale was found. This lack of variability is consistent with the application of current ultra-high energy cosmic ray (UHECR) models, which can produce secondary gamma-ray emission along the line of sight from the blazar; it also allows averaging over multiyear timescales without bias, aiding in the construction of spectral energy distribution …
Langmuir Probe Measurements Of An Argon Plasma, Andrew B. Hansen
Langmuir Probe Measurements Of An Argon Plasma, Andrew B. Hansen
Macalester Journal of Physics and Astronomy
In the field of thin-film research, there exists a novel method of film growth called Plasma Enhanced Chemical Vapor Deposition or PECVD. This technique utilizes the energetic electrons released from a plasma discharge to help catalyze chemical reactions in the deposition chamber that are essential to the film-growth process. Because plasma dynamics are not very well understood, much research goes into developing techniques to characterize a plasma's properties. In our research, we examined techniques used to measure the current versus voltage characteristic of an Argon plasma by use of a Langmuir Probe with the ultimate goal of determining the plasma's …
Kinetics Of Solid Phase Crystallization Of A-Ge Thin Films, John D. Graham
Kinetics Of Solid Phase Crystallization Of A-Ge Thin Films, John D. Graham
Macalester Journal of Physics and Astronomy
A method was developed to investigate the solid-phase crystallization (SPC) reaction undergone by germanium thin films. Amorphous films were grown by the radio-frequency (RF) magnetron sputtering and then annealed for a maximum of 6 hours at two temperatures: 446°C and 460°C. Crystallinity was measured by resistivity measurements, as well as crystal peak height and area taken from X-ray diffractometer (XRD) data. Initial data shows qualitative agreement with a nucleation-growth model for the observed kinetic process. However, observed peak narrowing phenomena suggests a comprehensive model of XRD measurements of polycrystalline thin films is needed for a rigorous interpretation of the results.
Finesse Measurement In Fabry-Perot Interferometers, Michael C. Darrow
Finesse Measurement In Fabry-Perot Interferometers, Michael C. Darrow
Macalester Journal of Physics and Astronomy
STAR (Space-time Asymmetry Research) is an experimental satellite that will measure anisotropy in the speed of light to unprecedented resolutions using two orthogonal Fabry- Perot interferometers. In order to achieve the desired level of precision, the optical cavities must have finesse values greater than 100,000. Using two test interferometers, I tested and optimized two different experimental methods for measurement of finesse: full-width half max measurement and cavity ring-down spectroscopy. Although each technique proved valid in its own right, my work suggests that cavity ring-down spectroscopy may be more applicable for the needs of STAR.
Force Constants Of Coordinated Co And Β-Amino Substituted Isocyanides Using Infrared Spectroscopy, Laura Avena
Force Constants Of Coordinated Co And Β-Amino Substituted Isocyanides Using Infrared Spectroscopy, Laura Avena
Macalester Journal of Physics and Astronomy
Metal carbonyls and isocyanides have characteristic peaks in infrared spectra. While the energies are useful in a qualitative determination of relative bond strengths, a more quantitative approach is needed to cross-compare similar complexes. Using a harmonic oscillator approximation, it is possible to determine the effective force constants of carbon-oxygen and carbon-nitrogen bonds. This allowed me to show that negatively charged bis(diphenylphosphinomethyl)diphenylborate used in our laboratory is a better donor than its neutral analogue 1,2-bis(diphenylphosphino)ethane.
Deposition And Analysis Of Copper Indium Disulfide For Photovoltaic Applications, Frederick Wade
Deposition And Analysis Of Copper Indium Disulfide For Photovoltaic Applications, Frederick Wade
Macalester Journal of Physics and Astronomy
Thin Film semiconductors were created through the methods of electrochemistry to produce a copper, indium and sulfur metal alloy that could be placed on a stainless steel substrate. We observed other properties regarding the relative indium to copper relationships and both the macro and micro structure of the final product. X-‐ray diffraction, SEM imaging, and atomic absorption spectroscopy data suggest a relatively intact metal alloy, but also an inaccurate ratio of indium to copper.
Photometric And Spectroscopic Analysis Of Young, Nearby Open Cluster Collinder 70, Clara M. Thomann
Photometric And Spectroscopic Analysis Of Young, Nearby Open Cluster Collinder 70, Clara M. Thomann
Macalester Journal of Physics and Astronomy
We present the results of a wide-field (80’ x 80’) photometric and spectroscopic survey of the young open cluster Collinder 70, which is also known as the ORI OB 1b association, centered on the central star of Orion’s belt, ε Ori (Alnilam). Seventy Coll 70 spectroscopy targets were selected from BVRIc color magnitude diagrams for observation using the CTIO HYDRA multi-object spectrograph; we aimed to identify targets exhibiting H" in emission and a strong lithium 6708Å line in absorption. About a third of our targets (23/70 stars) are consistent with being youthful members of Coll 70. Intermediate resolution (R!20000) HYDRA …
Monte Carlo Simulation For Silicon On Silane Hwcvd For Thin Film Solar Cells, Annaleigh Smith
Monte Carlo Simulation For Silicon On Silane Hwcvd For Thin Film Solar Cells, Annaleigh Smith
Macalester Journal of Physics and Astronomy
Thin film solar cells offer a viable alternative to crystal silicon solar cells. They are expected to be cheaper to fabricate because they use material more efficiently, and are deposited in a process which can create larger area solar cells [1]. However, a high deposition rate is necessary for economic viability. A Monte Carlo simulation can model the molecular interactions in hot wire chemical vapor deposition and track the position and velocity distribution of molecular species in the gas [2]. Determining the flux on the substrate can help us to increase deposition rate by adjusting control parameters accordingly [3]. As …
Galaxy Merger Identification In The Goods-South Field, Erin O'Leary
Galaxy Merger Identification In The Goods-South Field, Erin O'Leary
Macalester Journal of Physics and Astronomy
We analyzed a catalog of 7,628 galaxies at 0 < z < 4 from CANDELS1 in the GOODS-South2 field in order to identify a sample of galaxy mergers and interactions. Galaxy mergers are believed to play a fundamental role in galaxy evolution. Developing methods to robustly and efficiently identify mergers becomes vital with our increasing ability to study mergers at higher redshifts and in larger samples. We explored merger identification based on visual morphology classification and preliminary attempts with automated quantitative methods. Using multiple detailed visual morphology classifications for each galaxy conducted by the CANDELS structure and morphology team, we created selection criteria to …
Shield: Star Formation From Wiyn And Galex Imaging, Samilee J. Moody
Shield: Star Formation From Wiyn And Galex Imaging, Samilee J. Moody
Macalester Journal of Physics and Astronomy
Using images from the GALEX (Galaxy Evolution Explorer) GR6 pipeline (released 2010), as well as the WIYN 3.5m Observatory, we present a survey of the twelve SHIELD galaxies in the far-ultraviolet (FUV, 1500 Å) and near-ultraviolet (NUV, 2200 Å) filters. FUV data were available for eleven of the galaxies, AGC 749237 being the exception. Aperture photometry was performed on each image to determine the AB magnitude in the FUV and NUV filters.These values were then used to calculate flux, luminosity, and star formation rates (SFRs). Similarly, Hα images of each galaxy from WIYN (omitting AGC 749241) were analyzed to determine …
Numerical Modeling Of The Finite Well With Implications For Observing Quantum Interference Between Coherent Electron Wave, Jacob M. Moen
Numerical Modeling Of The Finite Well With Implications For Observing Quantum Interference Between Coherent Electron Wave, Jacob M. Moen
Macalester Journal of Physics and Astronomy
We use numerical modeling in Fortran to investigate the claims of Wollenhaupt et al. (2006) and Hommelhoff et al. (2002) regarding ultra-short electron pulses ionized via laser excitation of a tungsten nanotip. We assume that the nanotip acts as a finite one‐dimensional potential well with the depth equal to the work function of tungsten and the width of the order of the radius of curvature of the nanotip. The interactions of propagating Gaussian wave packets are modeled in order to give insight into the temporal and spatial evolution of the generated electron wave packets. Furthermore we hope to demonstrate the …
Synthesis And Characterization Of Zinc-‐Oxide/Polystyrene Nanocomposite Thin Films, Christopher Krapu
Synthesis And Characterization Of Zinc-‐Oxide/Polystyrene Nanocomposite Thin Films, Christopher Krapu
Macalester Journal of Physics and Astronomy
Ultra-thin films containing zinc oxide and polystyrene were prepared by sol-gel mixing and spincoating onto silicon substrate. Photoluminescent measurements were recorded following irradiation at 325 nm. We observed passivation of shallow defect states around 3.1 eV bandgap via confinement. Time-resolved photoluminescence plots suggest a significant time dependence of emission intensity related to photodegradation of the polymer matrix.
Growth Kinetics Of Zno By Magnetron Sputtering For Solar Cell Application, Nadia Foo Kune
Growth Kinetics Of Zno By Magnetron Sputtering For Solar Cell Application, Nadia Foo Kune
Macalester Journal of Physics and Astronomy
The goal of this work is study the mechanism of ZnO thin film deposition by rf magnetron sputtering with an argon plasma. This research will help understand the growth kinetics of the ZnO layer in relation to the growth conditions for solar cell application. We study the rate of growth, the electrical properties, the optical transmission and the zinc to oxygen ratio of each sample as a function of growth temperature. We conclude that Zn evaporation competes with incorporation into the film by combining with an arriving O atom.
Tip-Of-The-Red-Giant-Branch Detection: Estimating The Distance To Resolved Galaxies In Shield, Ian Cave
Tip-Of-The-Red-Giant-Branch Detection: Estimating The Distance To Resolved Galaxies In Shield, Ian Cave
Macalester Journal of Physics and Astronomy
The Survey of HI in Extremely Low-mass Dwarfs (SHIELD) is an ongoing study of twelve galaxies with HI masses between 106 and 107 Solar masses, detected by the Arecibo Legacy Fast ALFA (ALFALFA) survey. One of the important characteristics of a galaxy is its distance, since knowing that value allows us to calibrate many other factors and learn more about the galaxy. This research was focused on creating a program to systematically solve for the distance to the galaxies in SHIELD. To perform this calculation, Tip-of-the-Red-Giant-Branch (TRGB) detection was chosen, which is a popular method for galaxies with …
Electrical Conductivity Of Tellurium Nanowires On Pedot:Pss, Banteaymolu Alebachew
Electrical Conductivity Of Tellurium Nanowires On Pedot:Pss, Banteaymolu Alebachew
Macalester Journal of Physics and Astronomy
The purpose of this project is to understand the electrical conductivity and infrared absorption spectrum of a hybrid material between Tellurium nanowires and a carbon polymer called PEDOT:PSS. This hybrid material shows much higher conductivity than its components and this behavior gives a great promise for thermoelectric effect. The most intriguing property of this material is observed when taking absorption spectrum from far to near infrared. The hybrid material shows a much bigger absorption edge than Te NW. This project attempts to explain this shift using the confinement energy model and Fermi blocking (due to doping). The result from these …
Sub-Sonic Open-Return Wind-Tunnel And Measurement Apparatus, Michael Adams
Sub-Sonic Open-Return Wind-Tunnel And Measurement Apparatus, Michael Adams
Macalester Journal of Physics and Astronomy
Wind tunnels are an effective tool for understanding relationships between predicted and actual behavior of air foils in laminar flow. In order to improve the ability of Macalester College staff and students to observe and experiment with the effects of laminar air flow on various objects and systems, it was necessary to construct and test a sub-sonic open return wind tunnel. The purpose of the tests was to discover whether or not the air flow through the test section of the tunnel was laminar around the object being tested and also to evaluate the quality of an apparatus constructed to …