XII. Radiative transitions in light elements: II

Abstract

A survey is presented of our present knowledge concerning radiative transitions in nuclei of A ≤ 20. Over a hundred transitions, chiefly dipole, are analysed in terms of the Weisskopf units, and the following chief conclusions are drawn: (i) E1 transitions have a most probable speed of about 0·032 Weisskopf units with a spread in speed of about a factor of seven either way; (ii) The corresponding quantities for M1 transitions are a speed of 0·15 Weisskopf units and a spread of a factor of 20 either way; (iii) These distributions are consistent with shell model expectations; (iv) If a transition shows Г_γ(ev)/E_γ ³ (Mev)>0·02, then it is very probably E1; (v) There is no clear dependence of transition speed on level spacing or other feature; (vi) Some of the higher multipole transitions are inconsistent with shell model expectation and give evidence of collective motion.