Camille DuBois

In the Domestic Nuclear Detection Office Summer Internship Program at Lawrence Livermore National Laboratory, Camille DuBois conducted research on a cost-effective method to fabricate silicon structures used in thermal neutron detectors to help detect radioactive material.

From her childhood fascination with dinosaurs to her adolescent enthusiasm for the chemistry of cosmetics, Camille DuBois has long desired to be a scientist.

“I eventually grew out of my fantasy to become a paleontologist, but I did not surrender my interest in science,” said DuBois, now a senior in chemistry at Santa Clara University in California. “Learning and understanding the fundamental mechanisms of life is exciting, and a career path in the science, technology, engineering and math (STEM) fields has allowed me to contribute to our society in unique ways.”

DuBois has taken advantage of numerous opportunities to nurture her passion for STEM, including attending a six-week summer program in nuclear chemistry last year sponsored by the American Chemical Society and funded by the U.S. Department of Energy (DOE). That program inspired her to pursue additional nuclear research and education programs, including her most recent endeavor as an intern in the Domestic Nuclear Detection Office (DNDO) Summer Internship Program.

The DNDO Summer Internship Program provides students opportunities to participate in projects at federal research facilities across the United States. The program’s focus is to help DNDO meet its mission of implementing domestic nuclear detection efforts for a managed and coordinated response to radiological and nuclear threats, as well as integration of federal nuclear forensics programs.

At Lawrence Livermore National Laboratory (LLNL) in California, DuBois helped develop methods to manufacture thermal neutron detectors, which are devices used to detect and identify radioactive materials entering borders and ports.

Under the mentorship of electrical engineer Rebecca Nikolić, Ph.D., DuBois was responsible for developing a low-cost method to fabricate silicon microstructures for use in thermal neutron detectors.

Traditional thermal neutron detectors use helium-3 filled tubes; these detectors are prone to stability issues and are costly because of the scarcity of helium-3. Scientists at LLNL are funneling research into a different type of thermal neutron detector called a solid-state detector. It uses silicon pillars and boron-10, rather than helium, as the neutron-capture material.

These detectors are composed of a platform of silicon ridges, and the space between the ridges is filled with boron-10. When a thermal neutron enters the detector, it interacts with a boron-10 atom to produce an alpha particle and a lithium-7 atom. These particles strike the semiconductor silicon structures and produce an electrical signal, which indicates the presence and intensity of radiation.

So far, scientists have used a fabrication process for these pillars called plasma dry etching that demands the use of expensive, complex instrumentation. The abrasive nature of this technique induces roughening of the silicon surface, which decreases detector performance.

DuBois spent her summer fine-tuning a low-cost method called wet-chemical etching that requires only a hot plate, beaker, pellets of potassium hydroxide and water.

“The construction of high-performance neutron detectors available at an economical price is critical to meeting national security demands and promoting nonproliferation,” said DuBois. “These detectors help ensure the safety and protection of Americans from illicit nuclear materials.”

DuBois spent most of her days in safety glasses, gloves and a full body suit inside the cleanroom, investigating various wet-etching conditions and analyzing her results using a scanning electron microscope.

By the end of the summer, DuBois had broadened her technical skill set, improved her scientific communication skills, and experienced the dynamics of performing research at a national lab. She pushed her boundaries of knowledge by exploring unfamiliar concepts and is now pursuing graduate programs not only in nuclear engineering but also in materials science, a field she had not considered before.

“One of the best parts about pursuing a career in STEM is the sense of solidarity you feel with those in the STEM community, and I felt that a lot this past summer. It is comforting to meet others who won’t think you are ‘crazy’ when you tell them you love to study chemistry and nuclear physics,” said DuBois. “Overall, I had a very positive and valuable internship experience and certainly recommend the DNDO Summer Internship Program to others.”

The DNDO Summer Internship Program is funded by DNDO and administered through DOE’s Oak Ridge Institute for Science and Education (ORISE). ORISE is managed for DOE by ORAU.