Probing deformed nuclei: Experimental insights into excited states of 152,153,154Gd isotopes through fusion-evaporation reactions

The rare-earth region has been the focus of various studies aiming at the understanding of nuclear structure and providing information on the details of the reaction mechanism. The Gd isotopes belong to this group of nuclei and despite the available spectroscopic information, several open questions about their structure still exist, such as the inter-band transitions related to shape evolution or branching-ratios in deformed states. In addition, production cross sections of different reactions to Gd isotopes are largely unknown.

In this work, we report on an experimental attempt to populate the excited states in the isotopes ^152,153,154Gd by employing the heavy-ion fusion reaction ¹⁸O+¹³⁸Ba → ^156-xGd + xn in the 58-64 MeV energy range (center-of-mass). The experiment was conducted at the 9 MV FV Pelletron Tandem at the Horia Hulubei National Institute for Physics and Nuclear Engineering, employing the ROSPHERE array. Several branching-ratios for energy levels in ^152,153Gd have been measured, offering new and updated values. Furthermore, relative cross sections regarding the fusion-evaporation reactions ¹³⁸Ba(¹⁸O, 4n)¹⁵²Gd, ¹³⁸Ba(¹⁸O, 3n)¹⁵³Gd, and ¹³⁸Ba(¹⁸O, 2n)¹⁵⁴Gd have been measured and compared with theoretical calculations with PACE4.