Dating and Geographic Origin Flashcards
What is alpha decay?
Alpha decay is where an atom loses an alpha particle.
The resulting nucleus has an atomic number less than two and a mass number that is 4 less than the original nucleus.
What is beta decay?
A neutron is converted into a proton and an electron is emitted from the atom.
The product nucleus has an atomic number 1 more than the original nucleus.
What is positron emission?
A proton is converted to a neutron and a positron is ejected.
The atomic number is one less than the original nucleus although the mass stays the same.
What is electron capture?
The conversion of a proton to a neutron as the nucleus captures an electron from inner orbital.
Product nucleus has an atomic number one less than the original nucleus although the mass remains the same.
How is Carbon 14 produced and how is it distributed in the environment?
- Cosmic ray generated neutrons interact with 14N in the atmosphere.
- Neutrons from thermonuclear reactions interact with the 14N.
- 14C rapidly oxidises to 14CO and 14CO2
- This gets mixed into the atmosphere through plant uptake and ocean exchange.
Why is it advantageous to used AMS over radiation counters?
AMS counts the number of atoms in the sample, while scintillating counters measure the infrequent radiation decay events in the sample.
10mg C contains 6 x 108 atoms of 14C and AMS would give 1000 counts in 0.1 seconds while a scintillating count would take 5 days.
