The structure of N~Z nuclei filling the 1f7/2 shell is a challenging ground for both collective and single particle nuclear models. Large scale shell-model calculations in the full pf shell give an accurate description of the nuclei in the middle of the shell but as one moves towards the shell-closures some discrepancies arise.
More experimental data are needed to understand the origin of these disagreements. The structure of the N=Z 44Ti nucleus determined from high-spin gamma-ray spectroscopy presents many interesting features that deserve a special attention. Being an N=Z nucleus E1-type transition are forbidden but experimentally many such gamma-rays connecting the negative parity band to the ground state band we identified . The odd-spin branch of the negative parity band build on the 3- state has a strong resemblance with the ground state band up to spin 8+. Such experimental evidences might be associated to the contribution of some octupole-type correlations to the structure of this band. To clarify the underlying structure of the negative parity states, we performed a lifetime measurement using the IFIN Plunger device.
We report here on the lifetime measurement of the 3- state, obtained from the RDDS data by means of the Differential Decay Curve Method.
The preliminary results suggest an enhanced B(E3) strength for the gamma-ray transition from 3- to the ground state, that might be associated to the presence of octupole-type correlations, as mentioned before.
An small array of 5 2”x2” LaBr3:Ce detectors was also used during the measurement to allow for the determination of the lifetime for long-lived states. From the preliminary analysis of the data it results that the 4- state has a much longer lifetime than previously reported.
The new experimental results add important informations that new shell-model calculations has to take into account when explaining the structure of 44Ti.