AN INTERPRETATION OF THE LOW-LYING EXCITED STATES OF Mg²⁵ AND Al²⁵

A description of the experimental results obtained for Mg 25 and Al 25 is given based upon the assumption that the excited nuclear states are rotational states. In Mg 25 and Al 25 members of four rotational bands can be identified. The band based on the ground state can be assigned K = 5/2 whilst the three excited-state bands, two positive parity and one negative parity, can be assigned K = 1/2. The dipole γ-ray transitions between the K = 1/2 bands and the ground state K = 5/2 band are forbidden on the rotational model and it is a salient feature of the γ-ray cascading in Mg 25 and Al 25 that the ground-state transitions are always amongst the weakest transitions from excited states assigned to K = 1/2 bands. Besides giving a quantitative account of the γ-ray decay of the excited states the rotational model also predicts the number and type of the bands observed. The experimental values of the Mg 24 (d, p)Mg 25 deuteron stripping reduced widths can also be approximately predicted by the model.