We are taking a portable cosmic ray detector to Antarctica. We will use the collect data and also to better explain the operation of the IceCube Neutrino Observatory in our presentation in King George Island. This educational cosmic ray detector was developed by QuarNet to help students and teachers explore some aspects of particle physics and astrophysics. Dr. Jim Madsen from the University of Wisconsin - River Falls UWRF), and scientist with IceCube, supplied the detector.
Claire and Jim Madsen working with the cosmic ray detector
Once we set the equipment in Antarctica, we will be able to detect cosmic rays, charged particles that are more massive and easier to detect than the neutrinos. Imagine a proton moving almost at the speed of light approaching our atmosphere. The proton has been traveling for many years and is about to be destroyed. This particle has so much energy that it generates many different subatomic particles when it crashes into an atmospheric atom. The resultant particles will decay or collide themselves with other atoms. Suddenly, a shower of subatomic charged particles is created in the atmosphere, some of which make it to the surface of the Earth.
Our detector has four paddles made of a special plastic that produces light when the charged particles go through it. This process is called "scintillation", and differs from the Cherenkov radiation measured by the IceCube experiment that i continually produced by charged particles going through the ice. We detect the light produced by scintillation or Cherenkov radiation with a light sensor known as a photomultiplier tube (PMT). The PMT works like a lightbulb in reverse --- while a light bulb takes in electricity and sends out light, a photomultiplier tube takes in light and sends out an electric pulse. This light to electricity transformation is done using what is known as the photoelectric effect. The diameter of the PMT on each paddle (2 inches, 5 cm) is much smaller than those used in IceCube (10 inches, 25 cm), because scintillation produces much more light than Cherenkov radiation, and a larger fraction of this light reaches the PMT.
One of the Scintillating paddles of the cosmic ray detector
We can arrange the paddles in different configurations depending on what we want to study. Each paddle sends the electric pulse to a small data acquisition system, which processes and stores all the signals. We can learn about the direction from which the shower arrived if we place the paddles on the corners of an imaginary square. For example, if the shower came straight down, all four paddles would see a signal at the same time. An inclined shower gives a different time sequence.
Electronic board of cosmic ray detector
We have set the detector to collect data in my classroom so we can practice before going to Antarctica. We hope our data from Antarctica will be useful for QuarkNet, and the Astrophysics class at UWRF where they use the same systems,