The level structure of 90Mo

High-spin states of the N = 48 nucleus ⁹⁰Mo have been studied using the 33 MeV ⁹⁰Zr(³He, 3nγ) reaction. A previously unknown level structure above the 8⁺ isomer and several new lower-lying levels have been identified. The results are discussed in terms of shell-model calculations which allow four protons in the $\text{2}\text{p}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{and}\text{1}\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ subshells and two neutron holes in the $\text{1}\text{f}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{, 2}\text{p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{, 2}\text{p}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{,}\text{or}\text{1}\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ orbitals.