Mass spectrometry solves mysteries and unearths new questions in the Big Ideas Lab podcast

Scientists at Lawrence Livermore National Laboratory (LLNL) are solving cold cases and rewriting our knowledge of human history. Find out how the measurements made at the Laboratory’s Center for Accelerator Mass Spectrometry (CAMS) enable these feats on the latest episode of the Big Ideas Lab, available on Apple and Spotify.

CAMS is one of the most advanced and prestigious facilities in the world for measuring various ultra-rare isotopes and investigating the information they provide. It houses an array of powerful machines that analyze tiny atomic markers and discover answers to questions that have long eluded science, from archaeology to national security to public health and forensic investigation.

“It could be soil, it could be carbon dioxide, it could be coral, wood, charcoal, anything,” said Bruce Buchholz, a staff scientist at LLNL. “The reason carbon is so useful is that everything that's alive has carbon.”

Carbon-14 plays a key role in radiocarbon dating. Compared to carbon-12 and carbon-13, it has more neutrons and is much rarer. Accelerator Mass Spectrometry, or AMS, is designed to detect and count those rare atoms. By measuring how much radioactive carbon-14 is left compared to stable carbon-13 and carbon-12, scientists can determine a sample’s age, whether it’s 400 or 4,000 years old.

In many cases, AMS can help unlock the hidden history of human remains, breathing new life into cold cases and long-forgotten lives.

That’s exactly what happened in 2007 when police from Newfoundland, Canada, were six years into a murder investigation with nothing but dead ends. Using the radiocarbon bomb pulse — a spike in carbon-14 from above-ground nuclear testing that began in 1955 — as a timestamp, Buchholz and collaborators were able to determine the victim’s approximate date of birth and death. Combined with other advances, this identified the previously unidentifiable person.

And the diversity of tasks CAMS accepts extends far beyond cold cases. The same scientific techniques that help law enforcement identify a missing person can also reach far deeper into the past.

When a set of fossilized footprints were discovered in White Sands National Park, radiocarbon dating done at CAMS put them somewhere between 21,000 and 23,000 years old. This was up to 7,000 years earlier than previous evidence — dates that shocked everyone.

“There has to be so much humility to say we don't know anything about what people were doing in the western hemisphere for those 7,000 years,” said Susan Zimmerman, a staff scientist at LLNL who helped to date the footprints. “Suddenly we have to go, ‘Oh, we know almost nothing.’ And that is pretty cool.”

Find out more about these footprints and the science of CAMS on the latest episode of the Big Ideas Lab. Listen on Apple or Spotify.