calcium40

Calcium-40, often written as 40Ca, is the most abundant stable isotope of calcium. It has 20 protons and 20 neutrons, giving it a mass number of 40, and its atomic mass is 39.9626 unified atomic mass units. The nucleus is considered doubly magic, with both proton and neutron numbers equal to a magic number (Z = 20 and N = 20), which contributes to its high stability.

In nature, 40Ca accounts for about 97 percent of calcium. Calcium has six stable isotopes: 40Ca, 42Ca, 43Ca, 44Ca, 46Ca, and 48Ca. As a stable isotope, 40Ca does not undergo radioactive decay and remains essentially constant over geological timescales, making it a convenient reference point in isotopic studies.

Applications and significance: due to its abundance and stability, 40Ca is commonly used as a calibration standard in calcium isotope ratio measurements and in mass spectrometry. The 40Ca/44Ca ratio is frequently employed in geochemical and archaeological investigations to study processes such as mineral formation, diet, and environmental change. In nuclear physics and materials science, 40Ca serves as a target in experiments and as a reference for detector calibration.

In summary, calcium-40 is the predominant, stable calcium isotope with a doubly magic nuclear structure, playing a central role in both geochemical research and experimental calibration.