Nuclearg factors of the first and second 2+ states in192,194Pt

Theg factors of the first and second excited 2⁺ states in¹⁹²Pt and¹⁹⁴Pt have been measured using γ-γ angular correlations perturbed by the hyperfine field in an iron lattice. Bulk magnetizations of sources were examined with special care for different shapes of alloys and different magnetizing conditions. The following results have been obtained:¹⁹²Pt: 316 keV stateg=0.346±0.024, 612 keV stateg=0.455±0.089.¹⁹⁴Pt: 328 keV stateg=0.354±0.031, 622 keV stateg=0.316±0.029. These values are the largest ones which have been reported so far. The discrepancies between the present and previous data are discussed especially in terms of magnetizing conditions for the sources used. It is suggested that the difference ing factor between the first and second 2⁺ states may be in a certain correlation with M1 matrix element connecting these two states.     

Disparity in transient field characteristics for Au ions traversing Fe and Gd hosts through measurements ofg-factors in197Au

Transient field precessions were measured for levels in the nuclides of^182,184,186W and¹⁹⁷Au as their ions simultaneously traversed polarized Fe and Gd hosts. Consistent sets of gyromagnetic ratios were inferred for the lowest 5/2⁺ and 7/2⁺ states in¹⁹⁷Au using these two ferromagnetic host media, provided that (i) the transient field for Au ions in Gd is calibrated using the W in Gd precessions (simultaneously measured) and, (ii) the transient field for Au in Fe is calibrated using the field strength and velocity dependence for Pt in Fe (previously measured). The presentg-factor results are: g(5/2 ₁ ⁺ ;¹⁹⁷Au)=0.296±0.023, g(7/2 ₁ ⁺ ;¹⁹⁷Au)=0.241±0.021, and g(5/2 ₁ ⁺ ;¹⁹⁷Au)=1.2±0.2.     

Electric quadrupole and magnetic dipole moments of the first excited 2+ states of186Os and188Os

The spectroscopic quadrupole moments and the magnetic dipole moments of the lowest 2⁺ states in¹⁸⁶Os (137 keV) and¹⁸⁸Os (155 keV) have been determined by Mößbauer transmission experiments. The electric quadrupole momentsQ ₂₊(Os 186)=? (1.80±0.22) b andQ ₂₊(Os 188)=?(1.81±0.24) b as well as their ratioQ ₂₊(Os 188)/Q ₂₊(Os 186)=1.00±0.07 within the limits of error agree withB(E2) data, if a comparison on the basis of the rotational model is made. For the g-factors and their ratio g₂₊(Os 186)=0.281±0.008, g₂₊(Os 188)=0.305±0.015 andg ₂₊(Os 188)/g ₂₊(Os 186)=1.08±0.05 was obtained. All results are compared with recent model calculations.     

Theg-factor of the first 2+ state in192Pt by measurement of recoil into vacuum

Perturbed γ-ray angular distributions from the first 2⁺ states were measured for Coulomb-excited^{192,194,196,198}Pt recoiling into vacuum atv/c=0.010. Comparableg-factors were obtained for all four nuclei. Normalisation to the hyperfine field in¹⁹⁶Pt enabled both a comparison with a recent hydrodynamicg-factor measured in¹⁹²Pt and a cross-check of disputed Ir in Fe measurements. The followingg-factor was obtained:g(316 keV, 2⁺;¹⁹²Pt)=0.32(3).     

Determination of the paramagnetic correction factor of ytterbium

The Larmor precession of the first excited state of¹⁷²Yb has been measured by perturbedγγ-angular correlations in a liquid source at two different temperatures. By a comparison with theg-factor of this state directly obtained by other experiments the corresponding paramagnetic correction factors were deduced to beβ(20 °C)=2.61±0.27 andβ(33 °C)=2.43±0.27. For the ions Sm³⁺, Dy³⁺ and Er³⁺ the paramagnetic correction factors have been calculated from experimental data given in literature.     

Properties of isomeric states and the πd 3/2-vi 13/2 multiplet in194Au

The level structure of¹⁹⁴Au has been studied by observing prompt and delayedγ-rays following¹⁹⁴Pt(p,n) and¹⁹⁵Pt(p,2n) reactions. The conversion electron andγ-ray spectra from the decay of the 0.42s (10^?) and 0.60s (5⁺) isomers at 476 keV and 107.4 keV, respectively, have been measured using the He-jet method. The half-lives of the 6⁺ (278.2 keV, 1.1±0.4 ns), 7⁺ (224.6 keV, 2.6±0.2 ns) and 8⁺ (406.8 keV, 2.9±0.4 ns) members of theπd _3/2-vi _13/2 multiplet have been obtained from the time distributions between cyclotron beam pulses andγ-rays depopulating these levels. A calculation made assuming a pure two-particle configuration for the multiplet predicts very well theB(E2) values for the transitions between the levels of this multiplet but the calculatedB(M1) values are not in agreement with experimental results.     

The magnetic moments and halflives of the 5/2− states in199Hg and197Hg and the discrepancies in the experimental hyperfine fields at Hg in Fe

The Larmor-precession frequencies for¹⁹⁷Hg in Fe have been determined to beω _L = 1291 ±25 MHz at 293 K andω _L = 1334±25 MHz at 105 K. For¹⁹⁹Hg in Feω _L =1372±50 MHz has been measured at 293 K. The half-lives of the 5/2^? states in¹⁹⁷Hg and¹⁹⁹Hg have been remeasured asT _1/2(¹⁹⁷Hg)=8.1±0.16 nsec andT _1/2(¹⁹⁹Hg)=2.45±0.05 ns, respectively. The magnetic moment of the 5/2^? 158keV state in¹⁹⁹Hg was redetermined by the integral perturbed angular correlation method in an external magnetic field of 47kG asμ(5/2 ^? ) = 0.905±0.091 nm. With this new value consistency for the magnetic hyperfine fields at Hg in Fe measured with the TDPAC-method and with the NMR/ON-method is obtained. This fact is used to determine theg-factors of the 5/2^? states in¹⁹⁷Hg and¹⁹⁹Hg more precisely fromω _L -values given above:g(¹⁹⁷Hg)=0.342(6);g(¹⁹⁹Hg)=0.352(13). The magnetic moments of the first excited 2⁺ states in^198–204Hg isotopes which rely on calibrations with the¹⁹⁹Hg-g-factor, are revised.     

Mode-crossing signals of high order on the 4d 95s 2 2 D 5/2 state of Cd II isotopes

In the linearly polarized radiation field of a 442 nm He-Cd laser containing a natural isotope mixture, saturation-induced mode-crossing signals of the 4d ⁹5s ^{2 2} _5/2 state of Cd II are observed due to the even as well as the odd isotopes. The signal width of about 10^?4 T yields high resolution. Thus the signal splitting respective to the magnetic quantum number can be resolved. Theg _J - andg _F -factors of the² D _5/2 state are determined as follows:g _J=1.1980±0.0036,g _F(F=2)=1.397±0.008,g _F(F=3)=1.002±0.009.     

Mössbauer effect and nuclear moments of the 75 keV state of Dy161 and the 81 keV state of Dy162

The Mössbauer effect of theγ rays from the 74.5 keV state of Dy¹⁶¹ and the 80.7 keV state of Dy¹⁶² has been investigated. From hyperfine splitting patterns the magnetic moments μ(75 keV)=?(0.39±0.04) nm, μ(81 keV)=+(0.74±0.08) nm and the quadrupole momentQ(75 keV)=+(1.4±0.2)b have been determined. For the odd neutron nucleus Dy¹⁶¹ an effective spin g factorg _{s, eff}=0.76 g_{s, free} is deduced for the 75 keV level.     

On the decay of61Zn and60Zn using mass separated sources

The γ-ray spectrum of⁶¹Zn and⁶⁰Zn was studied with a 75 cm³ Ge(Li) detector using mass separated sources. For the half-lives we foundT _1/2(⁶¹Zn)=89.1 ± 0.2 sec andT _1/2(⁶⁰Zn)=2.33 ±0.05 min, together with the valuesT _1/2(⁶¹Cu)=3.26± 0.05 hr andT _1/2(⁶⁰Cu)=24.0 ± 0.3 min for the half-lives of the daughter activities.     

Disparity between the transient hyperfine fields for Pt and Os in Fe; an electron vacancy sharing interpretation

Precessions of the 2 ₁ ⁺ states in¹⁹⁸Pt and¹⁹²Os have been measured in the enhanced transient hyperfine magnetic field acting on these nuclei as they recoiled through thin polarized cobalt foils. Two separate targets consisting of contiguous layers of¹⁹⁸Pt and¹⁹²Os electrodeposited on ～1 μm and ～4 μm Co foils were employed. The levels of interest were Coulomb excited by 80 MeV³²S and 220 MeV⁵⁸Ni beams and the precessions of the 2 ₁ ⁺ →0 ₁ ⁺ γ-ray angular distributions in both nuclides were measured simultaneously. The results of these studies are compared with recently reported similar studies in which ions of¹⁸⁸Os and¹⁹⁴Pt recoiled through thin polarized Fe foils. It is concluded that (i) the transient field acting on Pt in Fe is singularly anomalous, and (ii) the recent contention that the g-factors of the 2 ₁ ⁺ states in the event Pt isotopes may be substantially lower than had been reported in the literature cannot be sustained. This transient field discontinuity is examined in terms of possible molecular orbital electron vacancy sharing between Pt and Fe.     

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 parametersv _p andC _ion C _atom 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 areH _h.f. (NdGd)=?1370±440 kG,H _h.f.(SmGd)=?1440±120 kG,H _h.f.(DyGd)=1410±400 kG,H _h.f.(ErGd)=2310±420 kG andH _h.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.     

Measurement of theg-factor of the 21 + state of192Pt in an external magnetic field

Theg-factor of the 2₁ ⁺ state of¹⁹²Pt has been measured by the IPAC technique in an external magnetic field as:g(2₁ ⁺,¹⁹²Pt)=+0.287(17). An additional IPAC experiment with an¹⁹²IrFe sample was performed with the same level in order to investigate the hyperfine field. The result:ω _L τ(2₁ ⁺,¹⁹²PtFe)=0.1115(9) gives the hyperfine field:B _hf ^4.2k (PtFe)=126.8(71) T. The result of an LTNO experiment with the same level is compatible with the assumption that 100% of the¹⁹²Ir atoms were on unique sites.     

Perturbed angular correlation measurement of theg-factor of the 668keV state in132Xe

A valueg=0.38±0.06 was obtained for theg-factor of the 668 keV state of¹³²Xe (τ=7.3±0.6 psec) from time-integral perturbed angular correlation measurements on gamma cascades in¹³²Xe. Sources of¹³²Te implanted in iron were used to obtain a magnetic hyperfine field of 1510±100 kG at the¹³²Xe nuclei.     

Gyromagnetic ratios of the 4+ and 6+ rotational states of184W

The nuclear Larmor precession has been observed for the 2⁺, 4⁺ and 6⁺ rotational states of¹⁸⁴W in the hyperfine field of WFe by application of the TDPAC and the IPAC techniques. A carrier free radioactive source of^184m Re alloyed with high purity iron was used for all three measurements. From the Larmor precession observed in the 2⁺ state by TDPACω _L = 944(15) MHz and the knowng-factor the hyperfine fieldB _{300 K} ^hf (WFe)=?69.6(27)T was derived. The deviation from the result of a spin echo experiment with¹⁸³WFe extrapolated to room temperature may be caused by the Bohr-Weisskopf effect (hyperfine anomaly). IPAC measurements with the same sample polarized in an external magnetic field of 1.6T gave for the 4⁺ and 6⁺ rotational states: ω _L τ(4⁺)=0.0609(22) andω _L τ(6⁺)=0.00735(102). By use of experimentalB(E2)-values theg _R -factors were derived asg _R (4⁺)=+0.276(26) andg _R (6⁺)=+0.281(45). The directional correlation of the 537?384 keVγ-γ cascade has been analysed in terms of anE1/M2/E3 mixture for theK-forbidden 537keV transition. We obtained the mixing ratiosδ(M2/E1)=±0.086(16),δ(E3/E1)=?0.028(5) with the sign convention of Krane and Steffen.     

Transition probabilities and hole-core coupled configurations in107In

The nucleus¹⁰⁷In was studied by in-beam spectroscopic methods in (HI, xn yp) reactions. Spin and parity values of some levels were determined by conversion electron andγ-ray measurements. Using the generalized centroid shift method, the half-lives T_1/2(19/2⁺, 2003.6 keV)=0.6±0.2 ns and T_1/2(17/2⁺, 1853.4 keV)=1.7±0.3 ns were measured. The systematics of the lowest members of the multipletπg ₉ ^2/?1 ×6 ₁ ⁺ in^111,109,107In is discussed     

Interactions of slow neutrons with the chromium isotopes

Neutron transmission experiments and determinations of coherent scattering lengths were performed on natural chromium and enriched samples of⁵⁰Cr,⁵²Cr,⁵³Cr and⁵⁴Cr. By means of the Christiansen-filter-technique we obtained new values for the scattering lengths of the bound atoms:b(^natCr)=3.635±0.007 fm,b(⁵⁰Cr)=?4.50±0.05 fm,b(⁵²Cr)=4.914±0.015 fm,b(53Cr)=?4.20±0.03 fm, andb(⁵⁴Cr)=4.55±0.10 fm. The transmission experiments with neutrons of 510 ΜeV, 1.26 eV and 5.19 eV energy resulted in data for the absorption cross sectionσ _a (^natCr) =3.05±0.08 b and for the scattering cross section at “zero energy”:σ ₀ (^natCr)=3.381±0.010 b. Data for incoherent and spin-state scattering and for the potential-scattering radius of the nuclei could be deduced from these results.     

Proton states in193Ir and195Ir populated via the (α) reaction

The nuclear structures of¹⁹³Ir and¹⁹⁵Ir have been studied using the¹⁹⁴Pt(t, α) and¹⁹⁶Pt(t, α) reactions. Levels up to ～2MeV in excitation energy were studied with a resolution of ～13keV (FWHM) and spectroscopic strengths were extracted. The low-lying states in¹⁹³Ir have been interpreted in terms of both the Nilsson and the rotation-vibration models including Coriolis, particle-vibration and rotation-vibrational couplings. The previously assigned 3/2⁺ [402], 11/2^? [505], 1/2⁺[400] and 1/2⁺[411] bands were populated and candidates for the 5/2⁺ [402] and 7/2⁺ [404] bandheads were observed. TheK ₀ +2 gamma vibration based on the ground state was populated because it is mixed with the 7/2⁺ [404] state. Surprisingly, there was no significant difference between the stripping and pick-up strengths for the low-lying states in¹⁹³Ir, suggesting that the equilibrium nuclear shape of¹⁹³Ir has large overlaps with the shapes of both¹⁹²Os and¹⁹⁴Pt. The nuclear level structure of¹⁹⁵Ir appears to be similar to those of the lighter iridium isotopes.     

Elastische Elektronenstreuung an14N,15N,16O und18O bei kleiner Impulsübertragung

Elastic electron scattering cross sections of¹⁴N and¹⁶O have been measured relative to the proton and of¹⁵N and¹⁸O relative to the lighter isotope (¹⁴N,¹⁶O resp.) using gas targets. The momentum transfer ranged from 0.22 to 0.48 fm^?1. The data were analyzed by phase shift calculations assuming harmonic oscillator shell model charge distributions. The following rms charge radii have been deduced: R_m(¹⁴N)=2.540±0.020 fm R_m(¹⁵N)=2.580±0.026 fm R_m(¹⁶O)=2.718±0.021 fm R_m(¹⁸O)=2.789±0.027 fm. The errors include statistical and systematic uncertainties and an estimate of effects due to the choice of the model. The radius differences of the isotopes are smaller than the values predicted by anA ^1/3 relation     

Measurement of50V and51V nuclear moments by nuclear magnetic resonance methods

From measurements of the Larmor frequencies of²H,⁵⁰V and⁵¹V in aqueous vanadate solution the ratio of theg _I-factors of⁵⁰V and⁵¹V and the nuclear magnetic moments of⁵⁰V and⁵¹V are derived. The ratio of the longitudinal relaxation times T₁ in VOCl₃ yields the ratio of the quadrupole moments |Q(⁵⁰V)/Q(⁵¹V)|=(3.99±0.14). In the 3d ³ 4s ^{2 4} F _3/2 atomic ground state the hyperfine structure anomaly is smaller than 1·10^?5.