ABSTRACT
Seniority was introduced by Racah (1943) as an additional quantum number, to distinguish between states of a given configuration which have the same values of angular momentum. In configurations of identical nucleons the simplest such situation arises in the ( 7 2 ) 4 https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780203739716/ff034a11-a369-4bc6-a470-f8cf1794dcb5/content/eq1853.tif"/> configuration for J = 2 and J = 4 states. The seniority scheme, however, is very useful also for states of the nuclear shell model which do not need an additional quantum number for their characterization. This is particularly true in semi-magic nuclei where, as mentioned above, ground states have lowest seniorities v = 0 in even nuclei and v = 1 in odd ones.
