Carbon 14 bomb pulse dating
One of his early projects at Livermore used bomb-pulse carbon to study how brain plaques form in Alzheimer’s disease (see sidebar: Reading the DNA Clock).In 2002, postdoctoral researcher Kirsty Spalding of the Karolinska Institute in Sweden came across a write-up of Buchholz’s work.A cesium gun shoots atoms at the smudge of graphite in the sample holder.The impact throws off electrically charged carbon ions, which are pushed and pulled down a 6-inch-wide tube by electric fields toward the accelerator.Counting atoms, counting years The accelerator mass spectrometer at LLNL, built in 1988, isn’t as energetic as the miles-wide accelerators used to shatter subatomic particles.But it’s plenty powerful for cutting-edge medical experiments.A dark legacy’s silver lining Manhattan Project scientists detonated the first nuclear bomb in mid-July 1945 in the desert of New Mexico. Nuclear bomb explosions liberated millions of neutrons, creating carbon-14 that quickly joined with oxygen to make heavy carbon dioxide.
The method, Buchholz believes, could help crack thousands of cold cases — if more investigators knew it existed. Carbon-14 normally is created in trace amounts by cosmic rays walloping nitrogen atoms high in the atmosphere.
After World War II ended, nuclear bomb testing intensified for nearly two decades as the Cold War deepened. In the 1990s, scientists speculated they might read that signature for scientific purposes.
“Everybody who’s been alive at this time has got this tracer in them, so let’s see what interesting science we can do with it,” Buchholz recalls thinking.
As he describes using toothbrushes to clean gunk inside the accelerator, Buchholz can't suppress a grin.
The spectrometer's heart is a brown school-bus-sized tandem accelerator.
A hunter spied the skull in 1968 along the banks of the Nechako River near Vanderhoof, a small logging and farming village 500 miles north of Vancouver, British Columbia.