48Ca

48Ca is a calcium isotope with atomic number 20 and mass number 48. It has 28 neutrons and 20 protons, placing it among the naturally occurring isotopes of calcium. The nucleus is relatively light but notable for its nuclear structure.

In nature its abundance is about 0.187% of natural calcium, making it the rarest of the naturally occurring calcium isotopes. It occurs in trace amounts in minerals containing calcium, such as calcite and dolomite.

48Ca is notable for its nuclear structure: the numbers of protons (20) and neutrons (28) correspond to magic numbers, making the nucleus doubly magic. It is regarded as the lightest known doubly magic nucleus, a feature that contributes to a relatively high binding energy per nucleon and distinctive nuclear behavior.

Decay and half-life: 48Ca can undergo double beta decay to 48Ti. This decay is extremely slow, with a half-life estimated on the order of 10^19 years for the two-neutrino channel; the neutrinoless mode remains unobserved as of now. Because of the long half-life, 48Ca is effectively stable on human timescales.

Applications and significance: The relatively large decay energy (Q-value) for its double beta decay and its simple nuclear structure make 48Ca a useful target in experiments searching for neutrinoless double beta decay. However, the isotope’s low natural abundance and the cost of enrichment limit its practical use. Enriched 48Ca is produced in specialized facilities and studied in dedicated detectors.

Occurrence and production: 48Ca is formed in stellar environments and is present in trace amounts in cosmic materials. In the laboratory, enrichment is achieved through mass separation and chemical processing of calcium.