speed dating in regina sask - Accelerator mass spectrometry ams radiocarbon dating

At the Laboratory, aside from modern and background standards, routine in-house measurements are also made on standards of like composition and age to the sample being dated.

The negative ions traveling down the beam tube are attracted (accelerated) towards the positive terminal.

At the terminal they pass through an electron stripper, either a gas or a very thin carbon foil, and emerge as positive ions.

The ions are slowed down and come to rest in propane gas.

As they stop, electrons are knocked off the gas atoms.

These electrons are collected on metal plates, amplified, and read into the computer.

For each atom, the computer determines the rate of energy loss and from that deduces the nuclear charge (element atomic number) to distinguish interfering isobars.Organic samples are converted to COC using an iron catalyst.Pressed graphite is sent to the Keck Radiocarbon Dating Laboratory at the University of California, Irvine and the Center for Applied Isotope Studies, University of Georgia for analysis.Several vacuum pumps remove all the air from the beamline so the beam particles have a free path.There are still lots of molecules and isobars (isotopes of neighboring elements having the same mass) that must be removed by more magnets after the accelerator.At this point the beam is about 10 microamps which corresponds to 10 ions per second (mostly the stable isotopes).

Tags: , ,