Becoming a scientist: Postdoctoral research

From undergraduate capstone research to graduate-level thesis work, our “Becoming a scientist” series has tracked up-and-coming scientists through their experiences at Sanford Underground Research Facility (Sanford Lab). The final step in research mentorship is the postdoctoral position, or “postdoc.”

“You’ve done the coursework, you’ve written your thesis and you’ve received your doctorate. Now, as a postdoc, you get a chance to start setting your own career in motion—changing fields, groups, experiments, and focusing on the full-time research that moves science forward,” said Markus Horn, staff scientist at Sanford Lab.

A postdoc program is a temporary position, typically offered through a university, that gives researchers an opportunity to pursue full-time research while gaining mentored experience after receiving their doctorate. While the position is valuable to researchers as they determine the trajectory of their career, it also provides a substantial, skilled workforce for developing experiments.

Of the 265 members of the LUX-ZEPLIN (LZ) dark matter collaboration, over 60 are postdoctoral researchers.

Some of these postdocs have contributed to the design and creation of the LZ from afar, and some have spent weeks at a time on-site at Sanford Lab, where the LZ experiment is being assembled. Postdocs have made multifaceted contributions—from hours spent carefully linking hundreds of photomultiplier tubes to data collection technology in the Surface Assembly Lab, to the underground assembly of a test circulation system in the Davis Cavern on the 4850 Level.

Doug Tiedt, a postdoc with the University of Maryland (UMD), is here for the long haul. Onsite at Sanford Lab for nearly six months, Tiedt’s postdoctoral work helps synchronize the efforts of dozens of researchers.

“We have a large number of graduate students, postdocs and faculty coming through and working in the assembly spaces,” said Tiedt. “Having someone here consistently really helps, otherwise you lose all the ground you’ve gained every three weeks when people leave or rotate out.”

In addition to his position as postdoc with UMD, Tiedt is the Cryo Coordinator for LZ. “I make sure all the parts for the circulation test come together in one piece,” said Tiedt. “By being onsite, I can communicate with other collaborators at UMD, helping them understand what's actually happening onsite.”

Tiedt, a graduate of South Dakota School of Mines and Technology, has been working in the underground environment at Sanford Lab on various experiments throughout his educational career.

“I wrote my Master’s thesis on the Deep Underground Neutrino Experiment, which was called the Long Baseline Neutrino Experiment at the time,” said Tiedt, who, in 2018, became the first student to graduate from the SD Mines physics PhD program with an experimental-focused dissertation. “My PhD thesis was written on the Large Underground Xenon experiment (LUX), LZ’s predecessor. Sanford Lab’s proximity to South Dakota schools was what made this research possible.”

Despite his extensive graduate involvement at Sanford Lab, Tiedt’s current postdoc position is still a learning experience. “There's still a lot of hardware things I'm learning, picking up from people on-site,” said Tiedt. “A huge part is project management, seeing the behind-the-scenes of funding, management and making sure everything gets done.”

As a postdoc, researchers take ownership of projects and propel scientific research, all while keeping an eye on the future. Careers in the research industry, professions as staff scientists and academic faculty vocations lie ahead, and postdoctoral experiences help researchers discern which track to pursue next.

“My next step depends on the job market in a few years,” said Tiedt. “Maybe I'll continue doing hands-on work, look for a staff scientist job or maybe even start looking for jobs in academia like a faculty position.”

Until then, Tiedt says there’s still a lot of work to be done, and he’s here for it.

“We just had the circulation test review, and now we are going through the results to make sure our systems are in order,” said Tiedt. “Soon, we will have authorization to actually put xenon in our circulation loop and test the system we’ve all been working together on.”

"These postdoc positions are valuable to both parties—the researchers, the experiments," said Horn. "Things get done for science, but individuals also get to test the waters of full-time research."