Summer 2003

Far Infrared Frequency Measurements Using The Three Laser Heterodyne Technique

Heidi Hockel and Mike Lauters, University of Wisconsin - LaCrosse

Abstract

An optically pumped molecular laser system has been used to generate short wavelength laser emissions in the far-infrared (FIR) region. In this experiment, a 1.5m long carbon dioxide (CO2) laser was used to optically pump a 2m long FIR cavity containing the methanol isotope CD3OH. The FIR laser utilizes an X-V pumping geometry, recently shown to efficiently pump short wavelength emissions below 100µm. Using the three-laser heterodyne technique, the frequencies of four distinct laser emissions, ranging between 67µm and 105µm, have been measured and are reported with a fractional uncertainty of ± 2 x 10-7 permitting spectroscopic assignment of the laser transition.


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Phonon Modes in InAs/AlSb Superlattices

Josh Matsko, Illinois State University, Normal, IL

Abstract

The InAs/AlSb heterojunction system is a lattice matched semiconductor system with type-II band alignment at the interfaces. This system is attractive to ultra-fast electronic device application due to its high mobility and large conduction-band offset. The superlattice can have two different interfaces: AlAs-like or InSb-like. These interfaces have very different interface roughness, mobility and carrier concentrations. There is experimental evidence showing preferential local arrangements of the interfacial atoms. First principle pseudo-potential calculations indicate that such superlattices with switched layers at the interfaces are more energetically favorable than superlattices with ideal sharp strained interfaces. We theoretically calculate the phonon modes of the InAs/AlSb superlattices using a one-dimensional linear chain model. We compare the interface modes for superlattices with the two different interface structures. We found that there not only are more interface modes in the superlattice with the switched interface layers, but that there also exist bulk modes at the interface, a special feature of this structure.

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Simple Climate Modeling

Suraje Dessai, University of Colorado, Boulder, CO

Abstract


Climate models are tools for scientific and policy analysis. Two simple energy balance models (EBM) of the climate of the earth were built for sensitivity studies. Using these models, we demonstrate that: changes in the albedo of the atmospheric-surface system contribute to radiative damping, solar variability is an important contributor to global mean temperature changes; a projection of future global temperatures reveal that by 2100, almost 50% of the greenhouse gas forcing will be due to nonCO2 greenhouse gases; the projection of global mean temperature changes shows an estimated increase by 2100 between 1 and 2 C; if the greenhouse gases are reduced by 5% (Kyoto Protocol agreement that levels at 2010 be reduced to 1990 levels), we estimate the mean temperature to decrease by 0.5 C by 2100. Evaluation of the one-dimensional EBM show that the simulated values are not significantly different from observed values at the 99% confidence value.

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A Self-Consistent Approach to the Laser Cooling of V-Type Atoms

Anthony Williams, Rowan University, Glassboro, NJ

Abstract

The equations of motion for three energy level V-type atoms driven by two counter propagating laser fields are derived from Schrödinger’s equation. These equations at steady state are reduced to a single integral equation for the ground state momentum distribution. A numerical method, based on a self-consistent approach, is developed to study the laser cooling of V-type atoms. A good agreement is reached between our numerical results and those from existing theory.¹

¹ Y. Castin, H. Wallis, and J. Dalibard, J. Opt. Am., B 6, (1989), p. 2046.

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Data Analysis for a Laser Band Displacement Monitoring System of a Silicon Strip Detector at CERN

Gyöngyi L. Marian, University of Alabama, Tuscaloosa, AL

Abstract


The Silicon Microvertex Detector (SMD) is a subdetector of the L3 experiment at CERN. We determined the global and local displacements of the SMD sensors by analyzing data from the Laser Displacement Monitoring System

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JURP Goes Online...the End of Paper Production Evolution

 

Rexford Adelberger, JURP Editor
Rexford Adelberger, Editor

The production of JURP has gone through many stages of evolution during the past 20 years. When, in 1981, the AIP executive board approved the founding of the Journal of Undergraduate Research in Physics as the Journal of the Society of Physics Students and its honor society Sigma Pi Sigma, a small grant was given to purchase an Apple II computer and an impact printer.

The original word processor used to format the articles is now an antique. It sits on a shelf to become part of a museum. It had no spell checker, no equation editor and no graphic capabilities, but could fit two 5 inch floppy disks. The hard disk in the Apple was so small that you had to change floppies to store the articles. The graphics were all formatted by hand, using a drawing board and an ink pen. It was a good thing that the editor had taken mechanical drawing in high school. During this time, the editor learned how difficult it is to proofread your own work. Once the copy was thought to be in proper English, the text for the articles were printed out in 4.25 inch wide columns and pasted onto a large sheet of paper in two column format. The equations were entered using press-on letters, and the graphics pasted into their appropriate places. The large story boards were then photographed, etched and printed.

After the first five volumes were produced, the production equipment was upgraded to a MacIntosh computer. The what-you-see-is-what-you-get format of the new word processor that could handle text, graphics and equations in a somewhat seamless manner was exciting and fun to use. The editorial office also purchased its first scanner and laser printer. It was truly amazing to the editor that he could scan in figures, and then use graphics software to modify and clean up the images. The pages of the journal now could be printed in photo-ready format with no need to paste various pieces of the copy into a story board.

The subscription list consisted of about 200 libraries and various individual subscriptions. The subscription list was kept on the same computer that produced the copy. Individual address labels were printed, and with the help of the editor's wife, were placed on the individual copies, each copy was sealed with tape, and then taken to the bulk mail area of the college's mail room. A large mailing consisted of about 700 copies.

As the editor also a professor of physics in a small liberal arts college, he received support from the college in the production of the journal. The college handled all of the financial record keeping and provided some of the costs of maintaining the editorial office a Guilford. This meant that the editor had to learn something about accounting, so that he could figure out how to read the balance sheets, etc. It became clear to him that accountants have a language and mathematics all of their own.

The editorial office moved with the editor as he went on sabbatical. Early on, one volume was produced on an old all-in-one MacIntosh computer in the city of Starnberg, Germany. The editor would format the copy while overlooking the alps and the Starnberger See. A Guilford, physics student, Dail Rowe, acted as business manager and handled the mail correspondence that came from Germany and all other things. A second time, the copy was edited and produced in the town of Kula on the slopes of Haleakala overlooking the paradise known as Maui. Again a Guilford physics student, Ari Betof, acted as business manager and ran the office at Guiford College. This time, communications were easy as the internet was available and very fast.

In 1987, the Society of Physics Students decided to send all members of the society a printed copy of the Journal. The production runs went from a few hundred to a maximum of 8 thousand. The mailing lists could no longer be kept at Journal office at Guilford College and labels printed. A bulk mailing service was used to send out the copies. Still another new skill had to be learned.

Then, yet another learning opportunity occurred; the old word processor that the editor finally mastered, was no longer supported. He had to start looking at other software systems to produce the copy. After many frustrating attempts to use WORD and WordPerfect to format the Journal, the decision was made to adopt PageMaker as the word processor. There were a couple of interesting consequences of the adoption of this word processor. First, and perhaps the most important at the time, was that the copy could be sent electronically to the printer. There no longer was a need to produce a hard copy that had photographed so that the journal could be printed using the off-set method.

The second is that it became possible to easily produce a copy of the Journal in pdf format. This made it possible to place old copies of the Journal in pdf format on a web page. The web page of the Journal is maintained by the American Institute of Physics and can be found at: http://www.JURP.org

At this time, the journal is no longer sent to each member of the Society of Physics Students. The current issue is still produced in a hard copy format that is sent to libraries and those individuals who subscribe to it.