High-spin states in the nucleiY91andNb95

Abstract

The positive-parity yrast states in the 91 Y and 95 Nb nuclei have been studied by γ -ray spectroscopy following heavy-ion-induced fusion-evaporation reactions. The lowest-lying transitions in these structures have been assigned via the p2n channel of the reactions of 12 C (38 MeV) and 16 O (48 MeV) beams with a 82 Se target, studied at the Bucharest Tandem accelerator. More detailed level schemes have been determined subsequently in a study performed with the GASP array of the inverse reactions produced by a 82 Se (470 MeV) beam from the Legnaro Tandem-LINAC accelerator with oxygen and possibly carbon contaminants of a 192 Os target. The observed level schemes are compared with local systematics and shell-model calculations.

High-spin states inNb96,97

“…The level scheme of 96 Nb deduced in the present work is shown in Fig. 3 [15], 94 Nb [16], and 95 Nb [17] isotopes, with respect to reactions in the target, and the complementary 117 Sn [20], 118 Sn [21], and 119 Sn [22], with respect to reactions in the backing, are indicated. 96 Nb is also a complementary fragment to itself.…”

“…The target consisted of 1 mg/cm 2 isotopically enriched 173 Yb, evaporated on a 7 mg/cm 2 gold backing (reactions of the beam in the backing produce a 221 Pa CN). In Experiment II a 199 Tl CN was formed in the 23 [15], 94 Nb [16], and 95 Nb [17] isotopes are indicated. Unlabeled peaks in both spectra are most likely contaminants.…”

“…6, where gated spectra on transitions assigned to 97 Nb and 96 Nb are shown. Transitions from the Nb complementary fragments [15][16][17] with respect to the 197 Pb (CN) and the Sn complementary fragments [20][21][22] with respect to 221 Pa(CN) are clearly indicated. N 58 of the first 2 + excited states in the even-mass Zr isotopes and of the first 13/2 + states in the odd-mass Nb isotopes.…”

“…2. Transitions from the complementary fragments 93 Nb [15], 94 Nb [16], and 95 Nb [17] relative to the 197 Pb compound nucleus are also indicated. Above the energies shown, there were no statistically significant peaks in the spectra in Fig.…”

“…The energies of the transitions are in keV. Transitions associated with the complementary 94 Nb[16] and 95 Nb[17] isotopes are indicated. 96 Nb is also a complementary fragment to itself.…”