40
Portland
Sunday Night
SPS04: 8-10 p.m. Capacitive Multiplexing on a High-Purity,
Germanium, 2-D, Planar Detector
Poster – Lena E. Heffern,* California State University, Chico, Physics Depart-
ment, Campus Box 202, Chico, CA 95929-0202;
Morgan T. Burks, Lawrence Livermore National Laboratories
Gamma-ray imagers based on high-purity germanium (HPGe) utilize
multiple segmented strips of germanium to determine the position of
gamma emitters. To cut down on the need for electronics, a simple readout
method involving capacitive multiplexing was developed. The goals of this
new method include maximizing the number of multiplexed channels,
maintaining high resolution, and determining the intrinsic capacitance,
and ground capacitance. Theoretical results are confirmed by experiment
on an EIGHT-strip, 2-D, dual planar, HPGe detector.
*Sponsored by Eric Ayars
SPS05: 8-10 p.m. Energy Efficiency vs. Tire Pressure and
Rolling Weight in Bicycles
Poster – Brody Boeger,* Portland State University, Department of Physics,
Portland, OR 97207;
Erik Bodegom, Portland State University
Cycling is one of the fastest growing modes of transportation in large
cities. As a result, bicycles and their function are of increasing interest to
an environmentally minded society. When utilized for transportation,
maintenance and efficiency become important aspects of cycling, but are
often overlooked by everyday riders. Using a standard bicycle, digital force
plates, and a power-metering hub it is possible to quantify the individual
and combined effects of tire pressure and weight on the bicycle in terms
of energy expended by the rider. Similar to studies on fuel efficiency in
automobiles, assessing an energy-efficiency value for bicycles provides ad-
ditional motivation for adopting sustainable transportation.
*Sponsored by Erik Bodegom
SPS06: 8-10 p.m. Integrated Physics Laboratory Assessment
Poster – Amanda Skuriat, Ramapo College of NJ, 505 Ramapo Valley Road,
Mahwah, NJ 07430;
,
Daniela Buna, Caroline Brisson, Ramapo College of NJ
The Engineering Physics program at Ramapo College of New Jersey has
conducted a comprehensive assessment of the department’s laboratory cur-
riculum in order to determine how to improve our student learning out-
comes. The data collected highlight the significant progress made through
the introduction of innovative laboratory equipment and teaching meth-
ods. However, evaluative feedback provided by the students on their work
was overly optimistic in comparison with feedback of their professors.
The findings also showed that there was a minimal increase in interest of
pursuing independent research among students. Therefore, it is imperative
to further analyze what aspects can be improved upon in the curriculum as
well as how to improve students’ evaluative skills and propagate increased
interest in the field. Several suggested tactics and future plans of action are
included with the best interests of our students in mind.
SPS07: 8-10 p.m. Temperature Dependence of the Persistent
Photoconductivity for ZnO
Poster – Cody V. Thompson,* Coastal Carolina University, Conway, SC
29526;
Christopher Moore, Coastal Carolina University
We have investigated the temperature dependence of the persistent
photocurrent observed for polycrystalline zinc oxide (ZnO) thin film
photodetectors. ZnO films were grown on c-plane sapphire substrates with
aluminum contacts, forming a metal-semiconductor-metal (MSM) planar
structure. The current across the ZnO films was measured before, during,
and after exposure to ultraviolet light with a 5-V bias across the contacts.
Ambient temperatures ranged from 20°C to 150°C. This process was
completed with several different ambient temperatures to observe changes
in the persistent photocurrent after removal of illumination. Results were
fitted to a temperature-dependent phenomenological model based on
thermionic electron transport across a time-varying surface-to-bulk energy
barrier.
*Sponsored by Christopher Moore. Funded by NSF DMR 1104600.
SPS08: 8-10 p.m. Modeling Gyroscopic Motion in Terms of
Linear Quantities
Poster – Harvey Kaplan, Purdue University, 525 Northwestern Ave., West
Lafayette, IN 47907-2036;
Rebecca Lindell, Andrew Hirsch, Purdue University
Gyroscopic motion is often described in terms of torque and angular
momentum. This method of describing gyroscopic motion proves to be
powerful, but conceals the forces responsible for the motion. Using the
VPython programming language, a simplified version of a gyroscope of
four identical masses is used to study the forces on each mass. The program
allows for effective analysis of gyroscopic motion in terms of forces and
linear momentum, and permits the user to increase the number of masses
until the limit of a physical gyroscope is reached. This program is intended
to serve as a pedagogical tool for understanding gyroscopic motion in
terms of forces.
SPS09: 8-10 p.m. Kerr Microscopy of Spin Currents in a
Metallic Nanowire
Poster – James T. Delles,* CSU, Chico, Physics Department, Campus Box
202, Chico, CA 95929-0202;
Andrew Galkiewicz, Paul Crowell, University of Minnesota
When a beam of polarized light is reflected off a magnetized surface, the
angle of polarization of the light changes with regards to the magnitude and
direction of the magnetization. This is known as the magneto-optic Kerr
effect. A spin valve is a device in which current is passed through a ferro-
magnet and due to the density of states of the electrons in the ferromagnet,
the leaving current is all of the same spin direction. It should be possible to
use the Kerr effect to measure this spin current created in a nanowire from
ferromagnets with their magnetization being out of the plane.
*Sponsored by Eric Ayars
SPS10: 8-10 p.m. Mpemba Effect in Water
Poster – Yuxin Wang, Southeast University, No. 2 Southeast University Road,
Nanjing, Jiangsu 211189, P. R. China;
Mpemba effect, referring to a phenomenon that hot water freezes faster
than cold under certain conditions, has been under discussion for a long
period of time. Based on the freezing mechanism, we first figure out that
the Mpemba effect is scientific by deducing the Newton’s law of cooling,
and then discuss the mechanism of Mpemba effect in theory. Experiments
about Mpemba effect were done on our own specific and certain condi-
tions. Via the experimental phenomena and data, we make further analysis
of the mechanism of Mpemba effect. In addition, we make assumptions of
a type of phenomenon about high energy level back to ground state, and
imply the applications from both microscopic view and macroscopic view.
SPS11: 8-10 p.m. Introduction and Research on Touch Screen
Technology
Poster – Yupeng Wang, No. 2 Southeast University Road, Nanjing, Jiangsu
211189, P. R. China;
Recently, touch-screen technology has been more and more widely used in
production and living. With the improvement of people’s living standard,
there will be a continuing increase in demand for electronic products, so
touch-screen technology has good development prospects. Our paper is
based on the principles of different types of touch screen and we focus on
the projected capacitive touch screen. We design a principal experiment to
have a better understanding of the projected capacitive touch screen and
do the preliminary research on it. We will introduce the three newest touch
screen technologies, “sol,” “on-cell,” and “in-cell,” in the paper. Ideas about
how to make the touch screen thinner, more sensitive, and user-friendly
are discussed, based on “in-cell” technology. We hope this paper will have
a positive effect on the research of optimizing the structure of future touch
screens.
