Publication Type
Journal
Journal Name
Nature
Publication Date
Page Numbers
454 to 457
Volume
465
Issue
7297
Abstract
Atomic nuclei have a shell structure1 in which nuclei with ‘magic
numbers’ of neutrons and protons are analogous to the noble gases
in atomic physics. Only ten nuclei with the standard magic numbers
of both neutrons and protons have so far been observed. The
nuclear shell model is founded on the precept that neutrons and
protons can move as independent particles in orbitals with discrete
quantum numbers, subject to a mean field generated by all
the other nucleons. Knowledge of the properties of single-particle
states outside nuclear shell closures in exotic nuclei is important2–5
for a fundamental understanding of nuclear structure and nucleosynthesis
(for example the r-process, which is responsible for the
production of about half of the heavy elements). However, as a
result of their short lifetimes, there is a paucity of knowledge about
the nature of single-particle states outside exotic doubly magic
nuclei. Here we measure the single-particle character of the levels
in 133Sn that lies outside the double shell closure present at the
short-lived nucleus 132Sn. We use an inverse kinematics technique
that involves the transfer of a single nucleon to the nucleus. The
purity of the measured single-particle states clearly illustrates the
magic nature of 132Sn.
