Electromagnetic transition strengths and nuclear moments in123Xe

Abstract

The level structure of lZ3Xe has been studied with the 114Cd(12C, 3n) and 114Cd (13C, 4n) reactions using in-beam 7-ray spectroscopy. The yrast cascade on the low lying odd parity states originating from the h~t/2 neutron orbital has been investigated yielding lifetimes r of 18(3) ps, 2.2(4) ns and 17(2) ns for the 15/2-, 11/2-and 9/2 states, respectively. The g-factor of the t~/z = 5.2 gs isomer has been measured to be g= -0.256(2). From the time differential observation of the electric quadrupole interaction in a 1~4Cd single crystal the spin of this isomer has been determined to be 7/2 and from the coupling constant eZQq/h=ll6(2)MHz the quadrupole moment was deduced. The results are discussed in the framework of the triaxial rotor plus particle model.

E2 moments andg-factors in neutron deficient lead isotopes

“…The latter option would be consistent with our data, if the expected 9-half-life accidentially equals the 12 + half-life with, at the same time, little feeding from this state into the U=9-level. The measured gfactor is compatible with both options of placing the 3.7 gs isomer, since both the I~=9-and any additional U= (7,8)-state have vi13/2 | (p, f) structure (see Table 4). The lifetime deduced for the 7 7 state is well in the range of the known 7---, 5-transitions.…”

“…The recoiling nuclei were implanted from the 1.2 mg/cm 2 target foil directly into solid Hg held at a temperature T =216K for the quadrupole experiment. For the gfactor experiment the target together with a lead backing, heated to T=448 K, was positioned in an external magnetic field of 2.88 (1)T. Further experimental details on detectors, geometrical set up and data handling in the standard PAD technique are given elsewhere [3,8,9]. The g-factors of two-and three-quasiparticle states in 195'196'197'198'199'2~176 were measured in the nuclear reactions 196't9SHg(cqxn) at 60 MeV beam energy on liquid isotopically enriched targets.…”

“…For intensity reasons in the 19~ experiment macropulses, consisting of 10 cyclotron beam pulses at the natural repetition time of 92 ns, were used at a separation of 25 ~ts to excite the isomer. A recoil catcher geometry was chosen [8] to reduce prompt background radiation in the 7-ray detectors. Target foils of isotopically enriched ~56'lss't6~ with a thickness of 2 mg/cm 2 were used.…”

“…The detectors were shielded against radiation from target and beam dump by 5 cm lead. Data were taken in standard 4 parameter list mode [8].…”

“…On the basis of a weak 541 keV-90 keV coincidence they assigned the 3.7 gs halflife either to the 7 i-state, which is excluded by the present lifetime measurement performed on the 318 keV 7-ray deexciting this state (see Fig. 4a), or to an additional U= (7,8)state between the U=9-and 7 r states. The latter option would be consistent with our data, if the expected 9-half-life accidentially equals the 12 + half-life with, at the same time, little feeding from this state into the U=9-level.…”