Ba138

Ba-138, or barium-138, is a stable isotope of the element barium (atomic number 56). It has 56 protons and 82 neutrons, giving a mass number of 138. It is the most abundant stable isotope found in natural barium, accounting for the majority of its isotopic composition.

Because Ba-138 is stable, it does not undergo radioactive decay and has no measured half-life. Its neutron number, N = 82, is one of the major magic numbers in nuclear physics, a feature that contributes to enhanced stability for certain nuclei. As a result, Ba-138 is typically used in studies and applications that require a non-radioactive reference isotope.

Natural occurrence and measurement: Ba-138 occurs in natural barium in the largest proportion among the stable isotopes. Its prevalence makes it a convenient reference point in isotopic analyses and mass spectrometry when quantifying the composition of barium in minerals, rocks, and environmental samples.

Applications: Ba-138 is widely used in high-precision isotope ratio measurements, including geochemical, environmental, and paleoclimate studies. It serves as a calibration and reference isotope in mass spectrometry and related techniques, aiding in the determination of barium isotopic compositions and helping to trace processes such as weathering, sedimentation, and oceanographic cycling.