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gamma36Cl

Gamma36Cl, often written as gamma-36Cl and more commonly referred to as chlorine-36 (36Cl), is a long-lived radioactive isotope of chlorine. It has a half-life of about 301,000 years and decays primarily by beta minus emission to the stable isotope argon-36. The decay may leave the daughter nucleus in an excited state, from which gamma rays can be emitted as it returns to the ground state; as a result, gamma radiation associated with 36Cl decay is observed in some measurements but is not the primary signal for dating.

Production and occurrence: 36Cl is produced cosmogenically in the atmosphere and near Earth's surface by interactions

Applications and measurement: 36Cl is widely used in geoscience and hydrology for dating groundwaters, ice, and

Safety and regulation: 36Cl is radioactive but presents negligible hazard at natural concentrations in environmental materials;

See also: radiometric dating, accelerator mass spectrometry, cosmogenic nuclides, groundwater dating.

of
cosmic
rays
with
target
nuclei
such
as
argon
and
potassium,
as
well
as
by
neutron
capture
on
35Cl
in
soils
and
rocks.
It
is
distributed
globally
but
remains
at
extremely
low
natural
abundances
in
chloride-bearing
materials,
with
its
concentration
controlled
by
production
rates,
chemical
behavior
of
chlorine,
and
geological
or
hydrological
processes.
Because
of
its
long
half-life,
36Cl
persists
for
geological
timescales
and
can
accumulate
in
chloride
reservoirs.
porous
rocks
on
timescales
from
tens
of
thousands
to
a
few
million
years.
It
serves
as
a
tracer
of
groundwater
recharge
and
past
climate
conditions.
Detection
at
natural
levels
relies
on
sensitive
techniques
such
as
accelerator
mass
spectrometry
(AMS);
conventional
gamma
counting
is
generally
less
practical
due
to
the
weak
gamma
signature
and
the
predominance
of
beta
decay.
handling
and
measurement
follow
standard
radiochemical
and
radiological
safety
practices.