First observation of the neutron-deficient nucleus⁹³Rh

Abstract

The gamma -decay of excited states in the neutron-deficient nucleus 93Rh has been observed for the first time. The fusion-evaporation reaction 58Ni(40Ca,3p2n)93Rh at 187 MeV beam energy was used to produce 93Rh. The multidetector array NORDBALL including particle selection was used for identification. From gamma gamma -coincidence data a decay scheme of 23 transitions up to high angular momentum was constructed for 93Rh.

β-delayed proton decay of a high-spin isomer inA94g

“…The resulting ␥-ray spectrum changes dramatically, as can be seen from the center panel of longer, while the spectrum is characterized by more than 20 other peaks. They match the ␥ deexcitation pattern of highspin states in 93 Rh which are known from in-beam ␥ spectroscopy [18]. Table II lists the ␥-ray energies and intensities, obtained from this spectrum, the half-life values deduced from analysis of the ␥-ray time characteristics (see Sec.…”

“…The 853 and 5447 keV levels are the only exceptions from this procedure. On the basis of the larger intensity of the 853 keV ␥ line relative to that of the 866 keV one, we conclude that these two transitions must be inverted in comparison with the earlier assignment [18]. The analogous conclusion is drawn for the 5447 keV state on the basis of the relative intensities of the 247 and 698 keV ␥ lines.…”

“…The proton-␥-␥ coincidence data (see fourth column of Table II) reveal further 93 Rh transitions, namely those at 148, 163, (273), 297, 382, 440, 546, 557, 570, 622, 654, 680, 695, 842, and 948 keV (parentheses indicate tentative assignments). Some of these transitions were observed by using in-beam ␥ spectroscopy [18], others are tentatively assigned because of matching the established energy levels in 93 Rh. Table III lists the experimental properties of 93 Rh levels, assigned on the basis of the proton-␥ and proton-␥-␥ coincidence data discussed above.…”

“…3 displays the resulting ␥-ray spectrum. Almost all ␥ rays represent transitions in 94 Pd, except for the ␥ ray of 853 keV, which is assigned to known transitions in 93 Rh [18]. The corresponding 93 Rh state is apparently populated via proton emission following the decay of 94 Ag.…”

“…The non-yrast levels are partially taken from data on the ␤ decay of 93 Pd [20], while the yrast-band assignments are adopted according to [18]. The 853 and 5447 keV levels are the only exceptions from this procedure.…”