Part of senior Rebekah Roundey’s research involved manip­u­lating radioactive beams from the
control room at the cyclotron institute. Rebekah Roundey | Courtesy

Senior physics major Rebekah Roundey said she likes to joke that she prac­ticed alchemy during her summer research project since the focus of her research involved trans­muting ele­ments.

Instead of attempting to turn lead into gold, however, Roundey’s research involved the pro­duction of radioactive nickel iso­topes, or dif­ferent forms of nickel with varying amounts of neu­trons in the atom’s nucleus, using state-of-the-art instru­men­tation at Texas A&M Uni­versity. She was able to syn­thesize nickel-51, a type of nickel that had not been made before using Texas A&M’s instru­ments.

“Our goal was to determine what iso­topes in the area of nickel-51 on the drip line can be pro­duced at the available energies,” Roundey said. “We then wanted to cal­culate the pro­duction rates of those iso­topes.”

Roundey wanted to determine whether adjusting the method for pro­ducing these radioactive iso­topes would help researchers to make the iso­topes more effi­ciently. She pre­sented her research at a poster pre­sen­tation for the Division of Nuclear Physics, and also pre­sented her work at Hillsdale last semester on Dec. 7.

She focused on a special group of proton-rich ele­ments with many more protons than neu­trons in their atomic nucleus.

“There are dif­ferent ways to transmute ele­ments,” Roundey said. “Radioactive or unstable nuclei decay nat­u­rally using either alpha, beta, or gamma decay, or you can fuse extra neu­trons onto a nucleus to make a dif­ferent isotope. You could add a proton or a neutron, or you could shave them off of a nucleus.”

Changing the number of neu­trons results in dif­ferent forms, or iso­topes, of the same element, while changing the number of protons causes the atom to become a dif­ferent element alto­gether. At a certain point, however, some atoms can’t accept any more protons.

“For some, there isn’t another isotope there because if you try to add a proton, it’s so unstable that the proton just drips off,” Roundey said. “So that’s why this line, the line where you can’t add another proton, is called the drip line.”

Under­standing the prop­erties and behavior of iso­topes along the proton drip line is important for nuclear astro­physics, Roundey said.

“Inside stars, nuclei are fusing, cre­ating new iso­topes, and if they’re going through rapid proton capture, they’re adding protons repeatedly,” Roundey said. “But if you reach one of these points where you can’t add another proton, they still want to keep adding protons, but first, it has to decay before it can start adding more protons.”

Since researchers can’t get up close enough to observe the inner workings of stars firsthand, they instead create the radioactive iso­topes in the lab using a cyclotron, an instrument that accel­erates par­ticles to high speeds. Roundey used the cyclotron to create beams of nickel ions.

“Cyclotrons are great if you want a beam of a stable isotope, but radioactive beams are important, so you have to find a way to produce radioactive beams from these stable beams,” Roundey said.

To make the radioactive beams, Roundey used the MARS spec­trometer, a par­ticular spec­trometer that runs the stable beam into a thick target, cre­ating a variety of par­ticles during the col­lision. The products of the col­lision are then sorted out based on their response to elec­tro­mag­netic fields, and detected based on their energy levels when they exit the instrument.

To determine how to create more of the radioactive nickel par­ticles, Roundey tried dif­ferent types of targets and a piece of carbon foil meant to serve as a filter. She found that the foil actually reduced yields, most likely because it pre­vented some of the nickel atoms from entering the instrument — a result she said was unex­pected.

She then ana­lyzed the data from the instrument and con­firmed the iden­tities of the dif­ferent iso­topes that were detected.

Her work at Texas A&M’s cyclotron institute used some of the same equipment used by NASA, the Jet Propulsion Lab, and by national defense orga­ni­za­tions and busi­nesses, according to Henry Clark, facility super­visor of the cyclotron institute and an accel­erator physicist. Other work at the cyclotron institute relates to supernova explo­sions and ultra-precise mea­sure­ments of the half-life of dif­ferent radioactive iso­topes. Roundey said the cyclotron institute is the only place that allows outside orga­ni­za­tions to pur­chase time to use the cyclotron.

The cyclotron institute is inter­na­tionally rec­og­nized for its research con­tri­bu­tions to the fun­da­mental under­standing of nuclear par­ticles, according to its website.

Chairman of the Physics Department Kenneth Hayes said Roundey was one of two Hillsdale stu­dents to conduct research at other col­leges over the summer through a national program that pro­vides under­graduate stu­dents with an oppor­tunity to conduct research.

“We encourage all of our physics majors to apply for summer REU posi­tions,” Hayes said in an email. “REU’s are very helpful for the stu­dents as they get to expe­rience what graduate-level research is like at a research uni­versity.  Also, having done an REU greatly strengthens a student’s appli­cation to graduate school … Hillsdale College physics majors have been quite suc­cessful in obtaining REU posi­tions.”

Roundey said working at Texas A&M was exciting, even though she has decided not to pursue a career in research.

“We can sit in the control room adjusting how the beam is being focused and tuned and see in the target chamber, how the beam is changing shape,” Roundey said. “It was really exciting and made me feel pow­erful to be fid­dling with these ancient knobs and watching a whole bunch of radioactive par­ticles moving around.”