Research @ KICP
June 15, 2005
From 6th Grade to the CMB
by Sarah Hansen
The <a href='ROOT/education/explorers/'>Space Explorers Program</a> is a multi-year extracurricular enrichment program for middle- and high-school minority students from Chicago's South Side who are interested in math and science. The goal for the 2003/2004 academic year was to have students measure the temperature of the Cosmic Microwave Background and understand the cosmological significance of that measurement. Students first investigated what temperature is and explored ways to measure temperatures of remote objects. After detailed discussions about cosmology, students determined the CMB temperature using state-of-the-art instruments. The results of the students' experiment are consistent with professional determinations, and represent the first time that such measurements have been made by pre-college students.
Microwaves are emitted by the atmosphere as well as by the CMB. Consequently, we must correct the measured power in our ground-based, 30 GHz experiment for the contribution from the atmosphere to our signal. This atmospheric foreground can be removed by measuring the total power received at different zenith angles. Most students in the program have not had trigonometry, so before doing the experiment we made physical models of the atmosphere. This hands-on learning helped students gain an intuitive understanding of the geometric relationship between zenith angle and atmospheric thickness.
<b>Summary.</b> The middle- and high-school students in the Space Explorers program spent a year developing the skills and conceptual foundation necessary to measure the temperature of the Cosmic Microwave Background. They strengthened their graphing skills, learned to make careful measurements, and analyzed complicated data. Along the way, they gained an understanding of the physics of how thermometers work, explored measuring temperatures of stars, and learned about cosmology. With professional instruments made available by the Carlstrom group at the KICP, the students successfully measured the 3K temperature of the Cosmic Microwave Background.
KICP Students: Sarah M. Hansen