Chatham’s Drift-Tube Mass Spectrometer: The Most Accurate in the World

By: Christina Binder

Back in April 2016, Dr. Larry A. Vieland, Dr. Jamiyanaa “Jami” Dashdorj, Dr. Rainer Johnsen, and Anbara Lutfullaeva collaborated to install a drift-tube mass spectrometer (DTMS) into Chatham’s Buhl building with the intention of improving the spectrometer’s accuracy via experimentation.
According to Dr. Viehland, the lead scientist behind the experiment, a drift-tube mass spectrometer is a type of device that can identify the properties of a substance, whether that substance is a solid, liquid, or a gas.
The device works by inserting a small sample of the substance into the machine and turning it into a group of electrically charged atoms called ions. In this case, the substance they used for this experiment was helium (He) and helium plus (He+).
The ionized helium, He+, proceeds to accelerate down an electrified drift-tube. They collide with the neutral helium at the other end of the tube. With each collision, the ions start losing speed and energy, eventually reaching a steady velocity where the ions can be analyzed.
Viehland said the experiment’s purpose was to find the drift velocity of helium as well as the different drift velocities for other elements on the periodic table as the experiment progresses. He also said that he wanted to explore a topic that “could be considered interesting to people, but was also something that not many people had explored yet.”
Regarding Viehland’s personal drift-tube mass spectrometer, he said that he had received his DTMS from fellow colleague, Dr. Rainer Johnsen, a retired Physics professor from the University of Pittsburgh and one of the four scientists that is working on the DTMS experiment.
Plans were made as early as October 2015 to install the DTMS into Buhl’s basement, but due to flooding concerns, it was moved to Buhl 131 (where the room itself had to be resized to fit the drift-tube mass spectrometer). The DTMS finally became operational in April 2016, having been in use for the experiment for the past year and a half.
On July 27th, 2017, the four scientists published a scientific paper showcasing their experiment as well as their findings. They found that their drift-tube mass spectrometer was the most accurate device of its kind in the world, measuring a difference of 0.6% between theoretical and actual values. When asked about how the findings could affect Chatham as a whole, Dr. Viehland said the experiment provides good research experience for any “slow, steady, and methodical” students that are interested in partaking. The experiment also opens opportunities for grant proposals that help support Chatham financially.
As a theoretical physical chemist, Dr. Viehland helped with the theoretical calculations in the experiment. He noted that most scientists lacked the theoretical mathematical skill necessary to perform the calculations, so Viehland took it upon himself to teach the other members of his group the specifics behind his theoretical calculations. “It is the responsibility of a university both to teach what is known and to expand [on] what is known.” Dr. Viehland said.
Dr. Viehland’s colleague, Dr. Dashdorj started working alongside him and the other scientists during the spring of 2016, one semester after he began teaching Physics courses at Chatham.
His previous work at the University of Alabama was very similar to Dr. Viehland’s work for the experiment, so Dashdorj happily took the opportunity to work alongside them.
Dr. Dashdorj would usually fix any technical issues that arose with the DTMS. For instance, if a certain part needed to be repaired, he would try his best to fix it. If neither he nor Viehland could fix it, then Dr. Johnsen would need to help. Dashdorj also helps calibrate the drift-tube mass spectrometer in accordance to Viehland’s theoretical calculations. “It is very inspiring to explore a thing that no one has done before.” Dr. Dashdorj said.
Observing as a curious witness, Dr. Aaron Trout, the professor of mathematics at Chatham University, occasionally visits Buhl 131 to check in on Dr. Viehland and Dr. Dashdorj as they work on the drift-tube mass spectrometer experiment. He also attends the group’s “seminars”, where Dr. Viehland explains his theoretical calculations.
When asked about his thoughts on the project, Trout said the experiment “looks like serious science.” Discussing some of the math that is involved, Dr. Trout notes that differential equations (the study of equations with varying rates of change) are needed to calculate the rates at which ions move through the drift-tube.
As the drift-tube mass spectrometer experiment is still ongoing and is expected to continue for years to come, the future looks bright for any students and faculty that wish to contribute to the project’s success.