Magnetic moments in ⁹⁰Mo: a discriminating test of the (g_9/2,p_1/2) shell model

New magnetic moments presented here allow stringent tests of the truncated shell model calculations performed in the region below the N=50 neutron shell. The experimental g-factors for selected medium-spin yrast states in ⁹⁰Mo were determined via the IMPAD technique using the ⁵⁸Ni(³⁵Cl,3p) reaction. The results of g(5^-, 2549 keV)=+1.10+or-0.28, g(11^-, 4842 keV=+0.42+or-0.13 and g(12⁺, 4556 keV)=+0.50+or-0.06 are used to show the that (g_9/2,p_1/2) configuration space with respect to a ⁸⁸Sr core is a rather successful truncation for the effective interactions but some shortcomings are exposed.