The investigation of the X(5) symmetry in a different mass region from the well established A = 150 region is a very actual topic in nuclear physics. The first example of an X(5) like nucleus, namely 178Os, outside the A = 150 mass region has been found by Moeller et al.[8,51].
From the energy spectrum, the neighbor nucleus 176}Os is considered as a good candidate for a nucleus where the critical point symmetry X(5) [2] can be observed.
The aim of this work is to test the model predictions based on the X(5) critical point symmetry in the 176Os nucleus.
Reliable and precise lifetimes of excited states in 176Os have been measured for the first time using the Recoil Distance Doppler Shift Method. Lifetime experiments were performed at the GASP array, INFN Legnaro and at the FN Tandem accelerator of the University of Cologne in combination with the Cologne plunger apparatus.
In 176Os, the lifetime of eleven excited states were determined using the Differential Decay-Curve Method. In addition, the lifetime of excited states in 177Os were measured. These states were populated in a weaker reaction channel.
In addition two dedicated experiments were performed to remeasure the lifetime of the first excited 2+ states in 176Os and178Os. The aim was to reduce the uncertainty of the B(E2; 2_1+ -> 0_1+) values, which are normally used to normalize transition strength within a nucleus for the comparison with theoretical models.
The comparisons between the experimental transition quadrupole momenta Qt of 176Os derived from the experimental B(E2) strengths and the predictions of the X(5) model confirm the consistency of an X(5)-like description of this nucleus
