Epsilon Notation (ε)
Definition
Similar to delta but expressed in parts per ten thousand, used for radiogenic systems where variation is very small. Epsilon Nd and epsilon Hf are the most common forensic applications.
- Scale
- Parts per ten thousand
- Common systems
- Epsilon Nd, epsilon Hf
- Contrast with delta notation
- Delta suits larger-variation systems, expressed per mil
Common questions
Why use epsilon notation instead of delta notation for radiogenic isotopes?+
Radiogenic ratios such as 143Nd/144Nd vary only slightly between samples, so expressing deviations in parts per ten thousand rather than per mil keeps the reported numbers at a convenient, readable scale.
Can epsilon Nd and epsilon Hf be measured on the same sample to cross-check a provenance conclusion?+
Yes, when the mineral or gem contains both elements in datable form. Because the two systems are geochemically independent, agreement between them strengthens confidence in the inferred source.
Related terms
- Delta Notation (δ)
- A notation expressing the isotope ratio of a sample relative to an international standard in parts per thousand (per mil, ‰). Positive...
- MC-ICP-MS (Multi-Collector Inductively Coupled Plasma Mass Spectrometry)
- An instrument that ionises a liquid or laser-ablated sample in an argon plasma at about 8,000 K and simultaneously collects multiple ion...
- Radiogenic Isotope
- An isotope produced by radioactive decay of a parent nuclide over geological time. Its abundance in a rock or mineral increases predictably...
- Stable Isotope
- An isotope that does not undergo radioactive decay. Ratios of stable isotopes change only through physical or biological fractionation, such as evaporation...
- TIMS (Thermal Ionisation Mass Spectrometry)
- An instrument that ionises a sample deposited on a metal filament and measures ion beam intensities with Faraday collectors. The gold standard...