Relativity

The Problem with Cosmic Rays

MEMO TO: Science Teachers at Jefferson Lab
FROM: Ray Latvidee, Physics Division
DATE: July 27, 2000

RE: DOE Grant MST-CRM

NASA has recently detected anomalies in the flux of cosmic ray muons coming to earth. As you know, these muons are produced at an altitude of approximately 9000 meters when high energy particles from space strike atmospheric atoms and cause nuclear reactions that lead to muon production. These muons travel toward earth at high speeds. We believe that very few make it to the surface because of the extremely short lifetime of the muon -- an average of 2 microseconds. Since this is a statistical average, we do expect some muons will make it. Based on the number of muons per second that actually strike a detector on the ground, there must an enormous number higher in the atmosphere. However, balloons and rockets launched from the NASA Wallops Island facility do not seem to bear this out. NASA handed the problem to the Department of Energy, which gave the problem to Jefferson Lab.

Members of the Physics Division found out about your presence at the Lab when we overheard a lunchtime argument at CEBAF Center between 2 rogue physics teachers and an Education Office bureaucrat on the occasion of her birthday. Shorthanded as we are, and very busy with projects from the construction of Hall D to the planned increase in beam energy to 12 GeV, it was unanimously decided that your group should be awarded the grant and the job.

We have already procured a portable muon detector for you made from parts left around Texas when the SSC was cancelled. We have also taken the liberty of arranging travel for you to consult with Dr. Cosimo Curre at CERN, the European Laboratory for Nuclear Research, just outside of Geneva, Switzerland. You'll have a week there with lodging at the CERN hostel and a rental car.

There are a few things you need to do first. You'll have to study up on cosmic rays and you'll have to measure the cosmic ray muon flux at sea level with your detector. You also need to find out the speed of a cosmic ray. After you explore the links below for background information, go the the next page to take care of these tasks.

Links for Background Information

CERN in 2 Minutes....Learn about CERN, what it is, and why it is there.

Cosmic Rays....An explanation of cosmic rays from the Stanford Linear Accelerator Center

Wallops Island....In case you were wondering what this Wallops Island place is.

Santa at Nearly the Speed of Light...a whimsical look at Relativity from Fermi News, the Fermilab publication.

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