APS News

Four Corners Section Holds First Meeting

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Four Corners Section Executive Committee attendees clockwise from left rear: Brenda Dingus (U. Utah), Andrea Palounek (LANL), Howard Voss (U. Arizona), Bill Evenson -Chair (Brigham Young U.), Mariet Hofstee (Colorado Sch. ), Scott Nutter (Eastern NMU), Harry Lustig (Sante Fe), Judy Franz (APS Executive Officer), Michael Petras (Motorola), Eric Jones - Sec. Tres. (Sandia), and J.D. Garcia - Chair-Elect (U. Arizona). Not in photo: David Wolfe - Vice Chair (U. New Mexico), Barrett Ripin (APS).

The fledgling APS Four Corners Section held its first annual meeting at the University of New Mexico, April 3-4. The section represents the APS members residing in Arizona, Colorado, New Mexico and Utah. The meeting began withpresentations of contributed papers on Friday afternoon, followed by a banquet, with keynote lectures by APS President Andy Sessler and Murray Gell-Mann of the Santa Fe Institute. Saturday's sessions included lectures on such topics as an update of current exciting research taking place at Los Alamos National Laboratory (John Browne), and Sandia National Laboratories (Thomas Picraux); physics research for next generation space systems at Air Force Research Laboratory (Janet Fender); and photovoltaic research and future directions at National Renewable Energy Laboratory (Satyen Debs).

Quantum Computing. There has been increased experimental interest in quantum computation since 1994, when it was shown that a quantum computer could efficiently factor large numbers and a scheme was proposed for realizing quantum logic gates with cold trapped ions. According to M.S. Gulley of Los Alamos National Laboratory, who spoke on Saturday morning, ions cooled to their motional ground state in a linear trap may be used as the individual qubits, and entangled states between these ions can be constructed using laser manipulation of the ions' states.

Neutron Testing of ICs. The high-energy neutron source at the Los Alamos Neutron Science Center (LANSCE) produces beams of neutrons for accelerated testing of integrated circuit devices, according to LANL's S.A. Wender. Neutrons produced in the atmosphere by cosmic-rays are thought to be a significant threat to integrated circuits at both aircraft altitudes and lower elevations, causing single event upsets, multiple event upsets, latchup and burnout in semiconductor devices. Neutrons are produced at LANSCE via spallation reactions with the 800 MeV pulsed proton beam. Proton beam currents of about 2 microamperes strike a tungsten target and produce a spectrum of neutrons whose energy and intensity can be precisely measured by time-of-flight techniques. The neutron spectrum produced in this manner is very similar in shape to the atmospheric neutron spectrum at 40,000 ft, with intensities over 100,000 times greater than the cosmic-ray neutron flux at 40,000 ft (sea level).

Four of the students receiving awards
Four of the students receiving awards ($100) for best presentations at the Four Corners Meeting. Student award winners are: Leslie Chavez (UNM undergraduate), Ronald Grazioso LANL, Chris Heil LANL (going to UNM in the fall as a grad student), Randy Jacobs LANL, J. D. Patterson (U of Colorado), Brian Roy (Colo School of Mines, undergraduate), Peter Schwindt (LANL, going to U of Colorado in the fall as a grad student), Morgan Wascko (LANL, UC-Riverside), Jason Webb (NM State), Marc Welliver (U of Colorado).

Thin Film Charged Particle Detector. Current charged particle detectors such as silicon barrier detectors are unable to operate at high temperatures or in a high radiation background. However, Brian A. Roy of the Colorado School of Mines reported that it is possible to construct a new type of charged particle detector that does not suffer from these restrictions. This involves the stacking of several alternating conducting and insulating layers. It is then possible to estimate the number of charged particles that stop in any given conducting layer, and hence the particle energy by measuring the current from the layer. Detectors based on this design have been built and tested with promising results, and a new detector is currently under construction that would greatly reduce its size. The linear particle accelerator, located at the CSM, will used to evaluate this new design.

Laser Induced Breakdown Spectroscopy. Jon E. Sollid of Coyote Mining and Environmental Instruments described a new technique for in-situ analysis of mineral exploration samples, dubbed Laser Induced Breakdown Spectroscopy (LIBS). The technique can be used to provide exploration companies with precise and accurate chemical analysis in the field in real-time, resulting in major time and cost savings, according to Sollid. Using a field portable analyzer, anomalies can be followed up immediately while crews are still in the field. Lower limits of detection LLDs are element dependent, but many are sufficiently low to be useful in exploration. LIBS analysis require little or no sample preparation.

NMR Studies of Fluid Flow. A collaboration of researchers at New Mexico Resonance and the Lovelace Respiratory Research Institute are using nuclear magnetic resonance (NMR) to non-invasively measure fluid structure, flow, and diffusion. Parameters measured include not only concentration but also higher order variables of the position, such as velocity, velocity fluctuation, diffusion, and dispersion. NMR makes these measurements along directions defined by magnetic field gradients so anisotropies of parameters can be measured. When combined with imaging, traditional NMR can yield spatial dependence of heterogeneities of these anisotropies.

Triple Flames. The study of (subsonic) combustion is divided for simplicity into "premixed" and "nonpremixed" regimes. However, according to LANL's Sandip Ghosal, a more realistic situation is the partially premixed regime, where the composition of the mixture varies continuously from pure fuel to pure oxidizer, as in the example of a fuel jet in an oxidizing atmosphere. In some such situations a particular 2D flame structure, known as a "triple flame" or "tribrachial flame," is observed. It consists of a curved premixed branch followed by a trailing diffusion flame. Ghosal has developed an asymptotic theory for the structure and propagation speed of triple flames, which he has compared with numerical simulations. Triple flames are thought to play an essential role in turbulent combustion, and, an understanding of their behavior may be of importance in modeling combustion problems.

Science Education. During a Saturday morning session, D.M. Riffe of Utah State University described the curriculum-wide integration of Mathcad into USU's undergraduate physics program. The foundation is a one-credit computer-laboratory experience in which the students work through a Mathcad handbook that teaches the students to use Mathcad in the context of solving physics problems. By working through the handbook the students gain familiarity with the functions of Mathcad that are most useful for solving undergraduate physics problems. To date, Mathcad has been used in at least 10 upper-division physics courses at USU.



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Editor: Barrett H. Ripin