Particle Accelerator

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Real-World Applications
ECU particle accelerator fuels discovery

By Meagan Williford
Photography by Jay Clark


Experiments conducted using the Department of Physics’ new two-million-volt particle accelerator could lead to life-changing discoveries in a variety of disciplines.

East Carolina University’s accelerator will allow faculty and students to delve deeper into interdisciplinary research in radiation physics, geology, anthropology and biology.

ECU’s new equipment is only the second particle accelerator in North Carolina, according to Dr. Jeff Shinpaugh, director of the ECU Accelerator Laboratory. The other is at Duke University. Students in ECU’s doctoral program in biomedical physics will use the state-of-the-art equipment to better understand topics such as radiation damage in biological systems and interactions in atomic collisions.

Research with real-world possibilities

The new accelerator will allow faculty and students to look at proton beams and heavier ions, which could not easily be done with the old accelerator. The improved equipment could provide key information in areas such as disease treatment.

For example, in the treatment of cancer, X-rays are used in traditional radiation therapy to kill tumor cells. A new therapy uses ion beams to deposit energy into the tumor. This type of therapy limits the damage to healthy tissue and concentrates it in the cancerous tissue. The lab at ECU focuses its research on the energy region where the ions deposit most of their energy and damage the most material.

According to Shinpaugh, there is still a lot of research to be done to understand how radiation interacts with biological systems. Many new proton beam therapy facilities have recently been built or are planned for construction.

“Already, in Europe and Japan, they have gone past the proton therapy and are using carbon beams for therapy,” he said. “We are not doing that in the United States yet, but eventually we will. One of my PhD students is going to look at the interaction of carbon beams with cells. The new accelerator will really help us expand the research we do with our PhD students in the program.”

Collaboration is key

The accelerator was acquired through an $867,982 grant from the National Science Foundation to physics professors Shinpaugh and Dr. Larry Toburen in 2009. Since then, space in the ECU Accelerator Laboratory in Howell Science Complex was renovated to accommodate the larger accelerator, which replaced the previously used 1970s model.

Research through the equipment will strengthen partnerships in disciplines all over campus.

“The research we are doing is not just in physics,” said Shinpaugh. “We’ve collaborated with faculty and their graduate students from the departments of biology, geology, anthropology and radiation oncology in the Brody School of Medicine. We can provide them with a very powerful tool for material analysis.”

Of the several ion beam analysis techniques that can be used in the laboratory, the most common is Proton Induced X-ray Emission (PIXE) analysis. In this technique, a beam of protons strikes a sample in a target chamber, and the material gives off “characteristic” X-rays.

“We have an X-ray spectrometer to analyze the emitted X-rays, which allows us to identify the elements present in the sample,” said Shinpaugh. “This is a very sensitive method of trace element analysis.”
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Previous research, Shinpaugh said, included looking at trace elements in water from the Tar River, the blood of patients who were undergoing radiation therapy and archaeological artifacts.

In the studies involving patients’ blood, faculty in the Department of Radiation Oncology looked for ways to treat some of the side effects of radiation treatments. When artifacts were found from what is thought to be Blackbeard’s pirate ship the Queen Anne’s Revenge, researchers in the lab were able to do a trace element analysis of the metal plating from a cannon, hoping to help identify the origin of the artifacts.

Shinpaugh also said that geologists and biologists have utilized trace element analysis. One of the graduate students in the master of science program in the Department of Geology studied foraminifera, tiny shell animals that incorporate whatever is in the water—including pollutants—into their shells. The student studied the foraminifera to trace the pollution outflow in a river basin in California. She was able to bring them into the lab and use PIXE for a trace element analysis.

Biology professor Dr. Roger Rulifson studies the migration patterns of fish along the Atlantic Seaboard, and researchers in the lab are able to perform PIXE analysis on the otolith (ear bone) of fish. The trace elements from the water incorporated into the bone matrix allow the biologists to identify spawning migration patterns of the fish.

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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.”

 

Invaluable experience particle_img4

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.

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