CROP is a statewide outreach project whose goal is to involve Nebraska high school students, teachers, and college undergraduates in a multi-faceted, hands-on research effort to study extended cosmic-ray air showers. High-energy (E > 1018 electron volts) cosmic rays which continuously strike the earth's atmosphere from outer space create avalanches of daughter particles which cover areas up to 50 square miles on the earth's surface. Using simple particle detectors placed in numerous locations, for example on the rooftops of high schools around the state of Nebraska, measurements of the original cosmic ray energy and incident direction can be made.
The precision of these measurements depends on the number, spacing, and characteristics of the rooftop detectors. CROP participants will contribute to our understanding of the origin of high-energy primary cosmic rays, which is a field of current and active fundamental research in physics and astrophysics throughout the world.
The aim of CROP is to develop an expanding set of high-school teams who construct, implement, and operate their school-based detectors in coordination with physics professors, graduate students, and undergraduate physics and science-education majors. Two-year colleges and science museums are also potential detector sites. The detection system at each site will be based on arrays of 1-meter by 1-meter plastic scintillation counters in weather-proof enclosures on the site roof. An array at a given location intercepts and detects a small portion of the shower particles (mainly muons, photons and electrons) generated by a primary cosmic ray. The rooftop detectors will be connected to associated triggering electronics and a data-acquisition computer located inside the building. Students will share and analyze the data from their individual sites via the Internet and search for time coincidences with multiple other sites; such coincidences signal the presence of extended cosmic-ray showers. Successful measurements require all existing detector sites to be collecting data simultaneously. Students will also share their data and experiences in video conferences and regional workshops organized around the 19 Educational Service Units in the state. In the long term when there are at least 30 operating school sites, physics results from CROP will be published in refereed scientific journals and will be presented by student representatives at international cosmic-ray research conferences and by their teachers at professional meetings: Nebraska Association of Teachers of Science, American Association of Physics Teachers, etc.
CROP will provide a vehicle for people at many levels -- from the high school student to the university professor -- to contribute to an exciting, statewide basic research and education initiative. The origin of the highest energy cosmic rays (predominantly nuclei of atoms from hydrogen to iron) incident on the earth's atmosphere and Nature's mechanism for accelerating them are major astrophysical puzzles. With detector sites covering the large geographical area of the state (75,000 square miles), CROP will complement other giant air shower arrays being developed where the detectors are more closely spaced, but cover a much smaller area. School sites in the Lincoln and Omaha area are close enough together to make significant measurements of primary cosmic ray energy and angular distributions for comparison with these major experiments. The more sparsely-spaced sites in western Nebraska will allow us to investigate very long-range correlations which indicate extensive cosmic ray bursts. The scientific impact of CROP will be strengthened in proportion to the number of detector sites which are collecting data simultaneously, making expansion and evolution primary goals after the pilot project.
Large numbers of students and teachers from high schools and two-year colleges in Nebraska will participate actively in a program of fundamental scientific research. They will gain hands-on exposure to the scientific method and modern research techniques, high energy particle detection techniques, computer programming, data analysis and statistics, communication across the Internet, video-conferencing, and discussion and presentation of results. CROP will foster partnerships across the state among high school students and teachers, and link these people to two-year colleges, to University of Nebraska professors and their research programs. Exposure to CROP could potentially lead a larger number of Nebraska high school students to major in a scientific discipline, an essential aspect of preparing our society for the next century.