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Description
The degree to which isospin symmetry is maintained across an isospin multiplet, and hence the extent to which the isospin quantum number can be considered pure, is matter of much contemporary interest. Tests of isospin purity have traditionally been undertaken through examination of the behaviour of the Isobaric Multiplet Mass Equation (IMME), with parabolic behaviour of the IMME of the lowest energy states of a multiplet being considered as a strong evidence for isospin purity. For excited states of multiplets, an alternative approach would be to examine electromagnetic transition matrix elements between analogue states, for which isospin selection rules impose specific behaviour as a function of Tz.. The E2 transition matrix element, in the limit of pure isospin, should be exactly linear with Tz for a T=1 triplet. The measured proton matrix element for the lowest transition, the E2 from the first excited T=1 2+ state to the first T=1 0+ state, can be used as a test of this rule. In this work, we present the results of an experiment to measure this B(E2) strength in the T=1 A=46 triplet
The experiment was performed at GSI, Darmstadt, using the AGATA array in conjunction with the Fragment Separator and the LYCCA array. For two members of the triplet, 46Cr and 46Ti, relativistic Coulomb excitation was used to determine the B(E2), whilst for 46V and 46Ti, lifetimes were measured using a new Doppler-shift technique which we call the stretched-target method.
The results are analysed in the context of all available data for B(E2)s for T=1 triplets. The A=46 case we will present represents one of the most precise tests of the linearity rule (matrix element vs. Tz) to date.
