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What are cosmic rays?
High energy electrons, protons, and complex nuclei can be produced in a number of astronomical environments. Such particles travel throughout the universe and are called cosmic rays. Some of these particles reach our Earth. As these objects hit our atmosphere, other particles called pions and muons are produced. These particles then slow down or crash into other atoms in the atmosphere. Since the atmosphere slows down these particles, the higher we travel, the more cosmic radiation we see. When you visit the mountains or take an airplane ride, you will encounter more cosmic radiation than if you stayed at sea level.
Cosmic Radiation Exposure: why does it matter?
Most cosmic radiation is very energetic. It can easily pass through an inch of lead. Since cosmic radiation can cause genetic changes, some scientists believe that this radiation has been important in driving the evolution of life on our planet. While cosmic radiation can cause some damage to individuals, it has also played an important role in creating humans. Our atmosphere is naturally shielding us from harmful effects. However, if we were to leave the earth and travel to some planet, we could be subjected to very high levels of radiation. Future space travelers will have to find some way to minimize exposure to cosmic rays.
Cosmic Ray Exercise
Power up a Geiger counter and set it to the most sensitive setting, make sure there are no radioactive materials nearby. Listen closely! You'll hear occasional beeps, some of which are from cosmic rays. Now, surround the counter with concrete or iron. Do you notice fewer beeps? That comes from the radiation being shielded away by the strong materials. For a real test, take the Geiger counter to a high-altitude mountain such as Mount Diablo and Mount Tamalpais. Measure how many counts you get there and let the counter run for 5 to 10 minutes (or more) to get results that are statistically accurate. Cosmic ray detections are random, so more time is equal to more reliable data.
The Berkeley Lab Cosmic Ray Telescope Project
The Berkeley Lab Cosmic Ray Telescope Project
We created a simple cosmic ray detector that can be built by high school teachers. This tool can measure the rate, energy, and direction of cosmic rays, and even how cosmic rays can vary with elevation. It's also a great way to introduce students to basic measurement and statistics. This detector is part of Berkeley Lab’s ABC of Nuclear Science online science unit.
On August 25, 2015, NPR used this detector on its program, All Things Together, to demonstrate how muons can be used to examine the core of the nuclear reactor at Fukushima.
In April of 2012, we gave this talk to the American Physical Society in honor of 100 years of Cosmic Ray Physics. We have both PDF and PowerPoint versions.
This is a presentation to the Seattle Cosmic Ray Workshop
In 2001, a group of teachers attended the High Energy Physics retreat at Snowmass and measured the flux of muon from sea level to 3.5 km. Find the link by clicking here.
Radman Zarbock, from the Athenian School in Danville, has done several interesting experiments with the Berkley Cosmic Ray Detector. These include studying the cosmic ray flux in a building and measuring the flux as one climbs a mountain. Click here. It provides more experiments using the detector and provides the results from it as well.
Here are descriptions of projects with the Berkeley Lab Cosmic Ray Telescope
Below is the completed detector being held by Colleen Twitty.
Supported in part through the generosity of the William F. and Edith R. Meggers Project Award, American Institute of Physics and Sens-Tech.
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