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The hfs separation Δν of 126Cs( T 1 / 2 = 1.63 m ) in the 6s S 1 / 2 2 ground state was obtained in a precision measurement near zero magnetic field by means of atomic beam magnetic resonance with laser optical pumping on-line with the CERN-PSB-ISOLDE mass separator. The result, Δ ν = 3629.514 (0.001) MHz, corrects significantly a previous published value from a high-field experiment. With our result, the precision of the nuclear magnetic moment, μ ( Cs 126 ) ≈ 0.776 μ N , is now limited by the influence of extended nuclear structure on the hfs (the Bohr–Weisskopf effect).

We have made high-resolution laser spectroscopy of the hyperfine structure of a radioactive isotope $^{179}\mathrm{Ta}$ (${T}_{\frac{1}{2}}=1.8$ y) using an argon-ion sputtering atomic-beam source. From hyperfine constants $A$ and $B$ of the atomic ground state ($^{4}F_{\frac{3}{2}}5{d}^{3}6{s}^{2}$), the magnetic dipole and electric quadrupole moments of the nuclear ground state of $^{179}\mathrm{Ta}(I=\frac{7}{2})$ have been determined for the first time: ${\ensuremath{\mu}}_{I}^{179}=2.289(9){\ensuremath{\mu}}_{N}$ and ${Q}_{s}^{179}=3.37(4)$ b. It is pointed out that magnetic moments of the ground and isomeric states in the region $N=102\ensuremath{-}112$ can be systematically described in terms of the presently available theory while the revealed systematic behavior of electric quadrupole moments is hardly reproduced by the theory.

The atomic-beam laser-rf double-resonance technique has been used to make precision measurements of the hyperfine structure (hfs) splittings in the 5${\mathit{d}}^{2}$6${\mathit{s}}^{2}$ $^{3}$${\mathit{F}}_{\mathit{J}}$ (J=2\char21{}4) states in $^{177,179}\mathrm{Hf}$ i. By making corrections to the second-order hfs effects, magnetic dipole (A), electric quadrupole (B), and magnetic octupole (C) hfs constants are obtained for the $^{3}$${\mathit{F}}_{\mathit{J}}$ states in $^{177,179}\mathrm{Hf}$: The constant C has a strong J dependence as well as does A and B; the isotopic ratio of the constant A between $^{177}\mathrm{Hf}$ and $^{179}\mathrm{Hf}$ has a significant J dependence, indicating J-dependent hyperfine anomalies, while that of the constant C is independent of J within experimental uncertainties, which is taken to be the ratio of the nuclear-ground-state magnetic octupole moments \ensuremath{\Omega}, i.e., \ensuremath{\Omega}${(}^{177}$Hf)/\ensuremath{\Omega}${(}^{179}$Hf)=-0.41(9). It is also pointed out that there is a clear indication of nuclear-spin dependence of the isotopic ratios of C. The single-electron hfs parameters of the 5d electron for the 5${\mathit{d}}^{2}$6${\mathit{s}}^{2}$ configuration in Hf i are obtained, and the Sternheimer shielding factor ${\mathit{R}}_{5\mathit{d}}$=-0.397(8) is derived.

Hyperfine structure of the 5${\mathit{d}}^{3}$6${\mathit{s}}^{2}$ $^{4}$${\mathit{F}}_{3/2}$ ground state in $^{180\mathit{m}}\mathrm{Ta}$ i was precisely measured by means of atomic-beam laser-rf double-resonance spectroscopy. Hyperfine-interaction constants A and B for the ground state $^{4}$${\mathit{F}}_{3/2}$ were determined with accuracies of 3 and 10 ppm, respectively. The nuclear electric quadrupole moment was derived, as well as a precise value of the magnetic moment for $^{180\mathit{m}}\mathrm{Ta}$ (${\mathit{I}}^{\mathrm{\ensuremath{\pi}}}$=${9}^{\mathrm{\ensuremath{-}}}$): the magnetic dipole moment is ${\mathrm{\ensuremath{\mu}}}_{\mathit{I}}^{180\mathit{m}}$=+4.825(11)${\mathrm{\ensuremath{\mu}}}_{\mathit{N}}$ and the spectroscopic quadrupole moment is ${\mathit{Q}}_{\mathit{s}}^{180\mathit{m}}$=+4.946(20)b.

The hyperfine anomaly gives an insight into the coupling of spin and orbital magnetic moments in the nucleus. More precisely, the nuclear magnetization is expressible through the nuclear wave functions with which is tested not only the magnetic moment operator, but also the tensor product [s×C2]1. The experiment can then be expected to be of value in testing the nuclear structure theory. The greatest value of these measurements is gained when these are made systematically over a large number of isotopes. We propose to initiate a program at ISOLDE to measure the hyperfine anomaly systematically in the heavy alkali elements. The experimental setup to achieve, in particular, a precise measurement of the nuclearg-factor is presented and the results on atomic beams of39K are discussed.

An on-line system of optical pumping in solids for the study of unstable nuclei was developed. The system is operated in connection with mass separators on line. The mass-separated unstable isotopes are implanted into a host crystal set at the focal position of the separator and then spin-polarized with laser optical pumping in the crystal. The crystal can be cooled down to 20–100 K with a cold finger attached to a liquid He bath. The achieved nuclear polarization/alignment is detected by observing the asymmetry/anisotropy of the emitted beta-/gamma-radiation with scintillation/Ge counters. Nuclear magnetic resonances are observed by detecting the destruction and/or enhancement of the asymmetry/anisotropy distribution with an applied rf magnetic field. The system has been applied to the study of unstable Tm and Si isotopes. Apparatus and performance of the on-line system are described together with some of the results obtained.

A direct measurement of the velocity distribution of ion beams from an ion-guide isotope separator on-line (IGISOL) was carried out at RIKEN with a technique of laser spectroscopy. The skimmer-potential and gas-cell pressure dependence of the velocity distribution were also measured. The velocity distribution was found to be about two times narrower than that estimated from the mass resolving power (MRP). It is pointed out that the velocity spread deduced from MRP is considerably overestimated at various conditions. The way of improvement to make the velocity distribution of the ion beam from the IGISOL narrower and the feasibility of fast atomic-beam collinear laser spectroscopy are discussed.

Angular distributions of the differential cross section σ (θ), analyzing power Ay (θ), spin-flip probability S(θ) and spin-flip asymmetry e (θ) in the excitation of the first 2+ states in 48Ti and 50Ti were measured at incident energies of 11 and 18 MeV using (p, p' γ) coincidence technique with polarized proton beam. The results were analyzed in terms of a macroscopic coupled channels method based on the vibrational model and of the microscopic distorted wave Born approximation (DWBA) based on shell-model wave functions and effective nucleon-nucleon interactions.

Angular distributions of the differential cross section, analyzing power, spin-flip probability, and spin-flip asymmetry in the excitation of the first 2{sup +} states in {sup 48}Ti and {sup 50}Ti were measured at incident energies of 11 and 18 MeV using the ({ital p},{ital p}{prime}{gamma}) coincidence technique with a polarized proton beam. The angular distributions show strong incident energy and target dependence. The results were analyzed in terms of a macroscopic coupled-channels method based on the vibrational model and of the microscopic distorted wave Born approximation based on shell-model wave functions and effective nucleon-nucleon interactions. The spin-flip asymmetry is quite sensitive to the spin-dependent part in the interaction that causes inelastic scattering.

The hyperfine structure of the radioactive isotope {sup 175}Hf has been measured by means of laser spectroscopy. The magnetic dipole and electric quadrupole moments of {sup 175}Hf are determined: {ital {mu}{sub I}={minus}0.62(3){mu}{sub N}} and {ital Q{sub s}}=+2.6(2) b; the sign of {mu}{ital {sub I}} has been shown to be negative. It has been shown that {sup 175}Hf has almost the same nuclear charge radius as {sup 174}Hf. {copyright} {ital 1997} {ital The American Physical Society}

Isotope shifts and hyperfine structures of four transitions in W i have been measured as well as isotope shifts in Lu i by means of atomic-beam laser spectroscopy. Magnetic-dipole hyperfine constants A of $^{183}\mathrm{W}$ are determined for the atomic states $^{7}$${\mathit{D}}_{1}$, $^{7}$${\mathit{F}}_{1}$, and $^{7}$${\mathit{F}}_{3}$ of the 5${\mathit{d}}^{4}$6s6p configuration. The nuclear parameters \ensuremath{\lambda} and \ensuremath{\delta}〈${\mathit{r}}^{2}$〉 are derived for W stable isotopes. J dependences of the isotope shifts are observed for the $^{2}$D term of the 5d6${\mathit{s}}^{2}$ configuration in Lu i and the $^{5}$D term of the 5${\mathit{d}}^{4}$6${\mathit{s}}^{2}$ configuration in W i. Parameters ${\mathit{z}}_{5\mathit{d}}$ of the crossed-second-order effects are derived for the Lu i 5d6${\mathit{s}}^{2}$ and W i 5${\mathit{d}}^{4}$6${\mathit{s}}^{2}$ configurations, and ${\mathit{z}}_{5\mathit{d}}$/\ensuremath{\lambda} is found to be 411(26) MHz/${\mathrm{fm}}^{2}$ for W. A systematic behavior of the normalized parameter ${\mathit{z}}_{\mathit{n}\mathit{l}}$/\ensuremath{\lambda}${\mathrm{\ensuremath{\zeta}}}_{\mathit{n}\mathit{l}}$ is discussed.

Extinction-to-backscatter ratio or lidar ratio is a key parameter in the issue of backscatter-lidar inversions. The lidar ratio of Asian dust was observed with a high-spectral-resolution lidar and a combined Raman elastic-backscatter lidar during the springs of 1998 and 1999. The measured values range from 42 to55 sr in most cases, with a mean of 51 sr. These values are significantly larger than those predicted by the Mie computations that incorporate measured Asian dust size distributions and a range of refractive index with a typical value of 1.55-0.005i. The enhancement of lidar ratio is mostly due to the nonsphericity of dust particles, as indicated by the T-matrix calculations for spheroid particles and a number of other theoretical studies. In addition, possible contamination of urban aerosols may also contribute somewhat in optically thin cases. Mie theory, although it can well describe spherical particle scattering, will not be sufficient to represent the scattering characteristics of irregular particles such as Asian dust, especially in directions larger than approximately 90 degrees when the size parameter is large.

Differential cross section and all four analyzing powers iT 11 , T 20 , T 31 and T 22 have been measured for deuteron elastic scattering from 208 Pb at incident energies from 10 to 23 MeV. The energy dependence of the tensor analyzing powers was investigated. A considerable deviation of the data from optical-model calculations including a T r -type tensor potential is found near the Coulomb barrier.

In monomode fiber the attenuation of higher order modes is much larger than that of the dominant mode near the cutoff wavelength. Therefore, in practice, the wavelength region in which only the dominant mode propagates is extended toward the shorter wavelength. A fiber used in the region in which two LP modes can theoretically propagate is called quasi-monomode fiber. This paper investigates the characteristics of the quasi-monomode fiber for application to communication channels. The behavior of the two modes near the cutoff wavelength is studied. The transmitted pulse waveforms, the effective cutoff wavelength and microbend loss are investigated. Based on the results, conditions for effectively preventing multimode dispersion are found even when coupling exists between these two modes. These conditions include the difference in loss factors, the coupling coefficient between the two modes and the relation between the fiber junction distance and the transmission distance. A measurement method is proposed for the coupling coefficient. It is shown that coupling of the two modes due to microbends, which are important for cable fabrication, creates increased loss not strongly dependent on the wavelength. Dependence of the effective cutoff wavelength on fiber length is clarified. It is shown that the effective cutoff wavelength of an entire length of cable can be estimated from a short sample.

The double differential cross section, the vector analyzing power, and the tensor analyzing powers for the /sup 4/He(d, p)n /sup 4/He reaction were measured at 12 and 21 MeV deuteron energy and in steps of 5/sup 0/ between 15/sup 0/ and 75/sup 0/ in the laboratory system. The experimental results are compared with the Faddeev calculations, in which three cases for the treatment of the neutron-proton interaction are tested. As a result, we can demonstrate what interaction is effective on each observable.

Measurements of the cross section, vector analyzing power, iT/sub 11/, and all three tensor analyzing powers, T/sub 20/, T/sub 21/, and T/sub 22/, have been made for the (d-arrow-right, /sup 6/Li) reactions on /sup 12/C and /sup 16/O at bombarding energies of 18 and 22 MeV. The observed large values of the tensor analyzing powers do not agree with distorted-wave Born approximation calculations assuming a one-step alpha-cluster transfer.