The science behind the machine
While particle accelerators can clarify many murky areas of scientific study, they are complex in both their construction and function.
“Everything that surrounds us is composed of atoms, and we use the accelerator to create a beam of charged atoms, called ions,” said Shinpaugh. “We make a negative ion beam using an ion source, and then we inject that beam into the accelerator. The negative ions are accelerated toward the positive two million volts inside the accelerator. Once the negative ions enter the high-voltage terminal at the center of the accelerator, electrons are stripped from the ions, changing them to positive ions. The positive ions are then repelled from the high-voltage terminal, traveling at a high speed.”
Because the acceleration of the ions is done in two stages, this type of accelerator is referred to as a “tandem” accelerator. As the ions exit the accelerator, they are traveling extremely fast. The switching magnet outside of the accelerator directs the high-energy beam to various experiments.
“We have this beam of fast ions we can crash into a target. Detectors are set up around the target, and we can observe what comes out of the collisions,” said Shinpaugh. “By doing spectroscopy on the products from the collisions, we can better understand the processes that occur when the ions interact with the target material.”
Working on experiments involving the particle accelerator gives students great experience they will be able to apply to any job they will have in the future. PhD students, master-level students, and undergraduate students are all able to participate in various experiments.
“There are all kinds of techniques students can learn in the lab that apply to many areas of science and engineering, such as vacuum technology, pressure measurements, data acquisition, data analysis and electronics design,” said Shinpaugh. “That’s in addition to the more specific training that they get in areas such radiation detection. This is a great learning experience for the students and allows them to get hands-on training.”
In experimental physics, according to Shinpaugh, researchers may encounter an experiment that requires new equipment. The instrument is designed and put together in the Department of Physics’ machine and electronics shops. The experiment is then planned and tested.
“This doesn’t usually work the first time, so the student must figure out why it didn’t work, make modifications, and try again,” he said. “That’s all a part of their training.”
The Radiation Physics group in the Department of Physics has received research funding of more than $3 million over the last decade from NASA, the National Institutes of Health, the U.S. Department of Energy and the National Science Foundation.