The accelerator mass spectrometry (AMS) to determine isotopic ratios for nuclides is probably the most sensitive analytical technique in the field of applied physics.
It provides for the measurement of the abundance of rare natural and artificial isotopes at levels of 10-15 compared to corresponding abundant isotopes.
The best known application of AMS
is the dating of radiocarbon (sup>14C) in items aged up to 50,000 years. Measuring the isotopic ratio 14C/12C, therefore provides the time passed since the death of the organism. The use of natural chronometers such as 14C finds a wide variety of applications, from archaeology to climatology, from hydrology to oceanography, from paleontology to paleomagnetism, from environmental physics to vulcanology.
The AMS is applied in nuclear safeguarding programmes and environmental radioactivity monitoring.
The addition of a known quantity of an isotope of the same
(“spike”)sample extends the use of the AMS technique to ultrasensitive measurements of the absolute abundance of each isotope. The sample undergoes complex radiochemical treatment to be prepared and is then placed in an accelerator (AMS system in use is based on a 3 million Volt terminal electrostatic tandem NEC 9SDH-2 Pelletron accelerator.
In the system’s typical configuration, the minimum detectable quantity of the rare isotope in the sample is 50 fg (femtogram – 10-15 g) , that must be reported. The AMS system in use is based on a 3 million Volt terminal electrostatic tandem NEC 9SDH-2 Pelletron accelerator installed in 2005.