Nuclear orientation

Article By:

Krane, Kenneth S. Department of Physics, Oregon State University, Corvallis, Oregon.

Last reviewed:June 2020

DOI:https://doi.org/10.1036/1097-8542.459400

Show previous versions

• Nuclear orientation, published June 2014:Download PDF Get Adobe Acrobat Reader

The directional ordering of the spins of a collection of nuclei with respect to some axis in space. The atomic nucleus is characterized by its spin, which represents the total angular momentum (including intrinsic and orbital) of all of the nucleons in the nucleus. Normally these spins are directed randomly in space (Fig. 1a), but under certain conditions imposed by the experimenter they can be forced into a preferred direction, and this ordering can be revealed by observing the radioactive decay of the nucleus or its behavior when undergoing nuclear reactions. If the oriented nuclei show no preference for direction along the orientation axis (that is, if there are equal numbers oriented forward and backward, or up and down), the nuclei are said to be aligned (Fig. 1b). If there is a preference for one direction over its opposite, the nuclei are said to be polarized (Fig. 1c). See also: Angular momentum; Spin (quantum mechanics)

The content above is only an excerpt.