Three-Quasiparticle Intruder State in Te125 and the Magnetic Moment of Sb125

The levels of Te125 have been studied using Sb125 nuclei, polarized at T=O.014°K in an iron lattice, and Ge (Li) detectors. The magnetic moment of Sb125 was determined as (2.59±O.03) PtN. Levels (spins) were assigned at 35.9(1+), 145.4(lj-), 322.2(j-), 443.7(probably i+), 462.5(!+), 525.4(probably !-), 636.1 (i+), 642.3 (i+), 671.6(!+) (energies in keY). The even-parity levels could be identified with levels calculated by Kisslinger and Sorensen. Using their wave functions, we calculated E2/Ml mixing ratios and branching ratios, finding quite good agreement. The odd-parity states are of special interest. The ¥­ 145.4-keVstate and t525.4-keV state are assigned as hU / 2 quasiparticle and hll(2 quasiparticle plus phonon. The tstate at 322.2 keY is not predictable on a single-quasiparticle-plus-phonon theory, and is assigned as a three-quasiparticle (hll/ 2)3 intruder state, bearing out Kisslinger's prediction that (j3)j_l intruder states should be found in low-lying spectra for high j. Evidence for other intruder states in Rh1oo, AgI09, and AgllO is given.