Friday, November 3, 2006

Experimental Physics: Field Trip to the Underground of the Twin Cities Physics Department

Participants from left to right: Len Keeler, Jacob Melby, Ryan Kalmoe, Anna Schliep, Arthur Aaberg, Sylke Boyd (behind camera)

On Friday, November 3, 2006, a group of UMM physics students and faculty traveled to the physics department of the University of Minnesota in order to learn about ongoing experimental research, survey laboratory equipment and to converse with graduate students and postdocs in “the mother ship” (Len Keeler). The trip was organized by UMM Prof. Len Keeler in cooperation with Professor Yuichi Kubota from UofM. Arriving on the TC campus at about 10 am, the group took a guided tour of several experimental laboratories with a variety of research objectives. During lunch with UMM graduate students and postdocs we received a few pointers for successful survival of graduate school, which are summarized below.

Here is what we learned:

	Superconductivity Located in the Sub Basement of the Physics Building, we visited the lab of Dr. Kevin Parendo (second from right), who graduated from UMM six years ago. He is investigating the properties of superconductivity in thin metal films. Superconductivity can be explained using the coupling between electronic states and phonons. As a thin film grows on the surface, a sharp onset of superconductivity can be observed as the thickness of the film approaches one monolayer. The apparatus consists of a large vacuum chamber with cryogenically cooled sample arrangement (1..100 mK), which is coupled to a deposition chamber. The apparatus can be seen in the background. This research is done under Professor Allen Goldmann.
Observational Cosmology Graduate student Tomo Matsumura is working in the group of professor Shaul Hanany which is measuring the microwave radiation background of the universe. While the intensity has been mapped over the past few years, the new direction includes a measurement of the polarization of the 3-Kelvin background radiation. The receptors are bolometers, which, together with the cryogenic chamber and the respective microwave optics, are transported into the upper stratosphere using helium balloons. The balloon experiments are carried out in New Mexico. The weight of the probes is about 1..1.5 tons, they will be recovered after the measurements. The probes are developed on the Twin Cities campus. The current project includes the development of half-wave plates which reliably can determine the polarization of the cosmic microwave background. This can be done by spinning the half-wave plate at high speed right above the bolometer. Tomo is developing this part of the apparatus, and is demonstrating to us a possible magnetic bearing. The bearing would use high-temperature superconductors in interaction with a spinning cylindrical magnet. The underlying physical effect is the Meissner effect.
	Thin Film Characterization Graduate Student Charlie Blackwell (right) is measuring the conductivity and photo conductivity of amorphous silicon films. He is working in the group of Professor James Kakalios. Amorphous silicon is used in solar panels, however, its photoelectric properties are degrading with exposure to light. Hence, there is an interest in improving its properties through better deposition techniques. Also, the reliance on dopants poses an environmental problem during production. Charlie is depositing films using Physically Enhanced Chemical Vapor Deposition (PECVD) and characterizing the films using a variety of tools, including TEM, FTIR, conductivity measurements under vacuum, and others.
	Liquid Crystals Under the guidance of Professor Cheng-Cher Huang, graduate students John Liu and Jack Han are characterizing liquid crystal films using the polarization of reflected laser light from the thin film. Liquid crystals are basically a preferentially ordered material consisting of asymmetric molecules. The disorder in the direction perpendicular to the ordered direction resembles that of a liquid. Liquid crystals are used in displays, body armor, lasers, but can also be found in cell membranes or other natural structures.
	Magnetic Vortices Professor Paul Crowell’s graduate student Robert Compton explained his spintronics experiment to us. A circularly polarized thin film of a ferromagnetic material will develop a magnetic vortex at its center. This vortex in the magnetization can be displaced by a pulsed external magnetic field, and measured by the rotation of the polarization experienced by an incoming laser pulse. The two pulses are arising from the same high intensity laser, and are produced using an arrangement of optical devices on an optical table. The “dancing magnetic vortex” is primarily of academic interest as it allows to probe nanometer sized effects of magnetization. It also allows to image defects or grain boundaries in this length range. The pulsing of the laser is in the Megahertz range, which enables the apparatus to visualize spin surface waves.
	Neutrino Oscillations Professors Ken Heller and Professor Yuichi Kubota talked to us about the MINOS experiment, which involves a neutrino beam directed at the Sedan Mine in Northern Minnesota. The solid neutrino detectors there are registering one to two events per day in capturing those neutrinos. These experiments have enabled the definite conclusion that neutrinos have mass, and that neutrinos oscillate between various types. A new detector (NOVA) is in preparation, which will be located off-center from the neutrino beam, and allow to register neutrino characteristics specific to the oscillation. The NOVA project is a collaboration of a large number of research institutions nationwide. Graduate Student Matthew Straight is involved in the detector development. The detector will consist of layers of PVC tubes filled with mineral oil in which the scintillator is dissolved. One part of such a layer can be seen in the upper picture. Optical fibers will be used to register the scintillation events. Matthew is developing an efficient method to insert the optical fiber loops into the PVC pipes, since about 600,000 of the will eventually have to be threaded. The apparatus shown in the lower picture allows to work with the fibers without breaking and bending.
	Self assembly and the origin of life Graduate Student Sean Corum talked to us about a project which aims to create an artificial functioning cell. The biological material (cell plasma plus incorporated organelles) is extracted from E. Coli bacteria, and after some processing inserted into membrane sacs. The goal is to start self sustaining life processes such as metabolism, propagation and active motion. This research is mentored by Professor Vincent Noireaux.

We also received first-hand tips from graduate students on what to watch out for when applying for Graduate School:

1. Have good letters of recommendation from your professors, in particular from your research advisors.
2. Take any opportunity to gain research experience, such as REU’s and others.
3. Maybe even volunteer your time to work on a research project as an undergraduate student.
4. Make sure, you do well in upperlevel classes such as Classical Mechanics, E&M, Quantum Mechanics.
5. It is beneficial to try to complete Griffith’s Quantum textbook as a directed study (I’m just the messenger).
6. Try to take Physical Chemistry to fill in the lack of Thermodynamics in the physics curriculum.

Thanks to everybody who took time for us and our curiosity.

Page maintained by Sylke Boyd.

Last modified 2006-11-07