calcium48

Calcium-48 (48Ca) is a calcium isotope with atomic number 20 and mass number 48, consisting of 20 protons and 28 neutrons. It is notable for being a doubly magic nucleus, since both the proton number (Z=20) and the neutron number (N=28) correspond to magic numbers in the nuclear shell model. This combination gives 48Ca unusually strong shell stability relative to neighboring isotopes and makes it an important case study in nuclear structure.

In nature, calcium contains 48Ca at a small but detectable fraction. Its natural abundance is about 0.187 percent of natural calcium. Because of this low abundance, 48Ca is one of the rarer calcium isotopes, though it is still observed in natural samples. Its stability is affected by a rare radioactive process known as double beta decay, which has been observed in 48Ca.

Nuclear decay and significance: 48Ca can decay via two-neutrino double beta decay to titanium-48 (48Ti), a process in which two neutrons convert into two protons with the emission of two electrons and two antineutrinos. The observed half-life for this mode is on the order of 4 × 10^19 years, and the decay releases about 4.27 MeV of energy (the Q-value). Neutrinoless double beta decay searches have also been conducted using 48Ca, but no such decay has been observed to date; results provide limits on the effective neutrino mass.

Applications and role in research: 48Ca serves as a benchmark for nuclear structure theories due to its doubly magic character. It is used in experiments studying double beta decay and in tests of shell-model predictions, contributing to broader questions about nuclear forces and neutrino properties.