NUCLEAR-STRUCTURE OF IR-192 STUDIED WITH DIRECT TRANSFER-REACTIONS

The nuclear structure of Ir-192 was investigated via the I-193(d, t) and Ir-191(d, p) reactions, using beams of 18 and 16 MeV deuterons, respectively. The reaction products were analyzed with a magnetic spectrograph, and detected with photographic plates. The energy resolutions (FWHM) of the detected particles were typically congruent-to 5.7 keV for the (d, t) and congruent-to 8.9 keV for the (d, p) reactions. Spectra were recorded at a large number of angles (greater-than-or-equal-to 15). The angular distributions of cross sections were fitted with theoretical distributions from DWBA calculations, and the spectroscopic strengths were obtained. For the (d, t) reaction, the fits to the angular distributions were performed in many cases with the sum of two l-values. Level energies, parities, spectroscopic strengths, and possible spin values were determined up to approximately 1 MeV excitation energy. Spectra were also recorded at a few select angles for the Ir-193(He-3, alpha)Ir-192 and Pt-195(p, alpha)Ir-192 reactions using beams of 25.5 MeV He-3 and 18 MeV protons, respectively. In order to obtain more information regarding the spins of levels in Ir-192, multidimensional scaling programs were applied to known gamma-ray intensities. The method appeared to be successful, and spins were suggested for many low-lying levels. The experimental results were compared with the IBFFM and the Nilsson model. It was found that the models can only approximately reproduce the structure of Ir-192.