R. Kalish

Magnetic moments of high-spin states above the rotational band of 168Hf and 172Hf

Abstract The transient magnetic field IMPAC technique was used to measure the magnetic moments of high-spin states above the rotational band of 168Hf and 172Hf, populated in the reactions 156, 160Gd(16O, 4n). The average g-factors of these prerotational feeding states were deduced to be 0.07 ± 0.04 and 0.14 ± 0.04 for 168Hf and 172Hf, respectively. These results are in agreement with a reduction of the collective g-factors due to a neutron phase transition.

Gadolinium as a ferromagnetic host for IMPAC experiments

The properties of ferromagnetic Gd as a host for IMPAC measurements have been investigated. The transient and internal magnetic fields at Cd, Nd, Sm, Dy, Er, Yb and Hf nuclei recoil implanted into polarized Gd at 80 K have been studied by the IMPAC technique. All available experimental transient field data for Gd have been analysed in the framework of the Lindhard-Winther theory. Empirical values of the parametersvp andCionCatom have been deduced which give good agreement between experiments and theory. Internal magnetic fields at rare-earth nuclei in magnetized Gd at 80 K have been deduced. The results areHh.f. (NdGd)=−1370±440 kG,Hh.f.(SmGd)=−1440±120 kG,Hh.f.(DyGd)=1410±400 kG,Hh.f.(ErGd)=2310±420 kG andHh.f.(YbGd)=−216±32 kG. The signs of these fields are, except for Yb which is in a 2+ ionic state, consistent with a ferromagnetic coupling between the 4f spins of the implanted ion and the Gd host. The deduced internal field at Hf in Gd is −440±90 kG. The observed time-dependent interactions for rare-earth nuclei in ferromagnetic Gd are consistent with the Abragam-Pound theory. For the Cd isotopes,g-factors of the first 2+ states were deduced from the experiments. The results areg(110Cd)=0.49±0.11,g(114Cd)=0.34±0.09 andg(116Cd)=0.41±0.11. The use of transient magnetic fields forg-factor measurements on high-spin rotational states is discussed.

Magnetic moment measurements of the first-excited 2+ states in even Nd isotopes

Abstract The g -factors of the first-excited 2 + states of 144, 146, 148 Nd were deduced from precession measurements in which the excited nuclei recoil through (TF IMPAC) or stop in (IMPAC) magnetized iron. The transient and static hyperfine fields which are active in these cases have been calibrated. The results for the g -factors, combined with previous data which were reanalyzed in the present work, are: g 144 = 0.15 ± 0.02, g 146 = 0.25 ± 0.04, g 148 = 0.32 ± 0.04. The g -factor for 144 Nd, which is abnormally low for a collective 2 + state, cannot be accounted for theoretically.

Half-life of the ground state of 53Co

Abstract The half-life of 53 Co(g.s.) was measured by observing its positron emission following the 39 K.( 16 O, 2n) reaction induced by a chopped 16 O beam. The contributions to the half-life of positrons from competing reaction products were considered. The final spin distribution and the isomeric ratio values for 53m Co 53 Co( g.s. ) and 53m Fe 53 Fe( g.s. ) were calculated by the spindependent nuclear evaporation model and found to be different, the former much smaller than the latter. The 53m Fe 53 Fe( g.s. ) isomeric ratios were measured for 39 K.+ 16 O as well as for 40 C + 16 O reactions and were found to be in agreement with the above theoretical prediction. On the basis of the smallness of the calculated 53m Co 53 Co( g.s. ) ratio, the half-life of 53 Co(g.s.) was determined to be T 1 2 = 262 ± 25 ms .

The transient hyperfine field at Si, Pd and Pt ions traversing iron and nickel foils

A measurement of the hyperfine interactions on swift28Si,110Pd, and194Pt ions recoiling through magnetized iron and nickel foils indicates that for these ions the strength of the transient magnetic field scales with the net magnetization of the ferromagnet.

Beta branch in the decay of 141mNd and structure of 141Nd

Abstract The allowed β-branch in the decay of 141m Nd has been observed and found to be strongly hindered. Comparison between log ft values for 141 Nd and 141m Nd yields information on the proton part of the 141 Nd wave functions, which are in agreement with results deduced from direct reaction studies.

The gyromagnetic ratio of the 208 KeV 32− state of 199Hg

Abstract The ion implantation perturbed angular correlation technique was used to measure the g-factor of the 3 2 − state at 208 keV of 199Hg recoiling into iron. A value g( 3 2 − ) = 0.35±0.11 was deduced from the data. This result is in agreement with predictions of an extended core excitation model.

New Methods and Results in Nuclear Moment Measurements Reported at the Uppsala Conference (June 10-14, 1974)

A summary of the measurements of magnetic dipole moments and electric quadrupole moments of nuclear states reported at the Uppsala Conference on Hyperfine Interactions (June 10-14, 1974) is given (in table form) The various methods employed for the measurements of nuclear moments (mostly of excited states) are reviewed, emphasizing the advantages and disadvantages of each. Possible future developments in nuclear moment measurements are discussed.

Transient field g-factor measurements for the 321+ AND 521+ states in 31P

Abstract Transient field integral precession measurements have been performed on the first two excited states of 31 P with the IMPAC technique on recoil into magnetized iron. The results were analyzed with an empirical parametrization of the transient magnetic field for light nuclei. This yields g -factors of g( 3 2 + ) = +0.20±0.05 and g( 5 2 + ) = +1.13±0.18 for the first and second excited state, respectively. These results are compared with calculations, which reproduce the measured values rather well.