- 36 There are about 200 isotopes of 35 elements that
are created by | fission,
but many with half lives of seconds
or minutes or hours decay rapidly and usually are not detected.
An indication is given in Table I of the number
of fission products to be expected in samples collected at
various times after origin and the percentage contribution
of individual fission products to the total activity of
all the fission products of common origin.
The importance
of knowing the age of the fission products when attempting
to identify the radioisotopes in a sample is apparent from
inspection of the data in Table I.
However,
if the age is
not known a reliable estimate often can be made from calculations of the ratios of certain observed radiolsotopes.
Since the ratios are constantly changing,
a particular ratio
will identify the age of the fission products,
providing
they are all of the same age and have not been differentially segregated by biological, physical or chemical
processes.
In the fusion process the nuclei of two atoms are
joined together to form the nucleus for one atom,
Opposite of the fission process.
just the
The nuclei of hydrogen
atoms are joined to form the nucleus of a helium atom