Statistical analysis of high-resolution inelastic electron scattering spectra,level densities and missing magnetic quadrupole strength in 90Zr

A fluctuation analysis technique and the comparison of experimentally deduced strength distributions with a statistical one have been used to extract level densities as a function of excitation energy from high-resolution inelastic electron scattering spectra. Both methods yield for the J^π = 2^? states around $\text{E}{}_{\mathrm{<mtext>x</mtext>}}\text{= 9}\text{MeV}\text{in}{}^{90}\text{Zr}$ mean level spacings 〈D〉 = 6.5±1.6 keV and 〈D〉 = 5.5 ± 1.5 keV, respectively. Those level densities are then employed to estimate the magnetic quadrupole strength that is hidden in the background and escaped direct experimental detection.