Three-Quasiparticle Intruder State in ${\mathrm{Te}}^{125}$ and the Magnetic Moment of ${\mathrm{Sb}}^{125}$

The levels of ${\mathrm{Te}}^{125}$ have been studied using ${\mathrm{Sb}}^{125}$ nuclei, polarized at $T=0.014\mathrm{}$°K in an iron lattice, and Ge(Li) detectors. The magnetic moment of ${\mathrm{Sb}}^{125}$ was determined as $(2.59\mathrm{}\pm 0.03) {\mu }_N$. Levels (spins) were assigned at $35.9(\frac{3}{2}+)$, $145.4(\frac{11}{2}-)$, $322.2(\frac{9}{2}-)$, $443.7(\mathrm{probably} \frac{3}{2}+)$, $462.5(\frac{5}{2}+)$, $525.4(\mathrm{probably} \frac{9}{2}-)$, $636.1(\frac{7}{2}+)$, $642.3(\frac{7}{2}+)$, $671.6(\frac{5}{2}+)$ (energies in keV). The even-parity levels could be identified with levels calculated by Kisslinger and Sorensen. Using their wave functions, we calcualted $\frac{E2\mathrm{}}{M1\mathrm{}}$ mixing ratios and branching ratios, finding quite good agreement. The odd-parity states are of special interest. The $\frac{11}{2}-145.4\mathrm{}$-keV state and $\frac{9}{2}-525.4\mathrm{}$-keV state are assigned as $h_{\frac{11}{2}}$ quasiparticle and $h_{\frac{11}{2}}$ quasiparticle plus phonon. The $\frac{9}{2}$- state at 322.2 keV is not predictable on a single-quasiparticle-plus-phonon theory, and is assigned as a three-quasiparticle ${\left(h_{\frac{11}{2}}\right)}^3$ intruder state, bearing out Kisslinger's prediction that ${\left(j^3\right)}_{j-1\mathrm{}}$ intruder states should be found in low-lying spectra for high $j$. Evidence for other intruder states in ${\mathrm{Rh}}^{100}$, ${\mathrm{Ag}}^{109}$, and ${\mathrm{Ag}}^{110}$ is given.