The magnetic moment of the 10+ isomer in140Ce and temperature dependence of the paramagnetism for Ce ions in BaO

The g-factor of the first 10⁺ isomer in¹⁴⁰Ce was determined by the time differential perturbed angular distribution method. The result is g(10⁺) = +1.03(4). The paramagnetism of Ce ions in BaO was studied in the temperature region 300 – 850 K.     

Magnetic moment of the 19/2+ isomer in135Ce

Employing the time-integral PAC technique with an external magnetic field, the g-factor of the 19/2⁺ state at 2,125.6 keV in¹³⁵Ce was determined to be g=?0.07(1). This value favours a predominant (h ₁₁ ^2/?2 s ₁ ^2/?1 ) neutron configuration for this level. Its meanlife has been redetermined with improved precision to be τ=11.8(5) ns.     

States inN=80140Nd populated in the decay of140Pm

The level structure of theN=80,¹⁴⁰Nd has been investigated through the beta decay of^140m Pm and^140g Pm, whose decay half-lives were measured to be 5.95±0.05 min and 9.1±0.5 sec, respectively. Decay schemes for the two isomers have been constructed fromγ-ray measurements. With the help of the beta decayft values and internal conversion electron measurements, spins and parities were deduced for levels in¹⁴⁰Nd. Among the levels a 7^? state at 2222.0 keV and a 5^? state at 2273.3 keV are identified as two-neutron quasiparticle states. The (ie233-01) for^140m Pm and^140g Pm have been deduced as 7^? and 1⁺, respectively. From beta end-point measurements, the decay energies of the two isomers have been determined asQ _EC=6.48±0.07 MeV^140m (Pm) andQ _EC=6.08±0.10 MeV (^140gPm). The results are discussed in the light of nuclear systematics of theN=79 and 80 isotones.     

The magnetic moment of the 19/2− isomer in85Rb

The magnetic moment of the 19/2⁻ isomer in⁸⁵Rb has been measured by means of the TDPAD method providing μ=+1.3(4)μ_N. From this value the dominating three-quasiparticle structure πp _3/2 ⁻¹ pg _9/2 ⁻² has been deduced for this state.     

Determination of absoluteK-internal conversion coefficients of some transitions in Ce140 by the internal-external conversion method

The internalK-conversion coefficients of the 331, 431, 815 and 933 keV transitions following the decay of La¹⁴⁰ have been determined absolutely by the method of comparing internal and external conversion lines measured in a double — focusing beta — ray spectrometers. TheK-internal conversion coefficients of the 4+→2+ 487 keV transition in Ce¹⁴⁰ was used to normalize relativeK-electron and gamma-ray intensities for these transitions. The results obtained are:α _K (331)=0.04432±0.00471,α _K (431)=0.28110±0.02913,α _K (815)=0.00396±0.00043,α _K (933)=0.00282±0.00031. Multipolarity assignments based on these values are suggested. The 815 keV transition is found to be pure magnetic dipole character in good agreement with the theoretical values calculated bySliv andBand. The 331 and 933 keV transitions are proved to have magnetic dipole character withE2/M1 equal 0.2852±0.0143 and 0.1750±0.0088 respectively. The 431 keV transition was found to have magnetic octupole character. The results obtained are most consistent with the assignment 2+, 4+, 2+, 3+ and 1+ for the 1597, 2084, 2184, 2410 and 2515 keV levels respectively.     

Evidence for near equality of neutron and proton radii in the N = 82 isotones

Quasielastic (p, n) data have been taken on the ¹³⁸Ba, ¹⁴²Nd and ¹⁴⁴Sm isotones at E_p = 26 MeV. Analysis with a folding model suggests a ratio of neutron-to-proton rms radii near unity which does not increase with increasing neutron excess.     

Measurement of the magnetic moment of the 7+ isomer in 198Tl

Using the atomic beam magnetic resonance method the hyperfine structure separation of $\text{1.9}\text{h}{}^{\mathrm{198m}}\text{Tl}\text{(I}{}^{\mathrm{\pi }}\text{= 7}{}^{\mathrm{+}}\text{)}$ has been measured in the ${}^2\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ atomic ground state. From the hyperfine structure splitting the nuclear magnetic dipole moment has been deduced. The results are: Δν = 4500 (68) MHz, μ_I = 0.641(10)μ_N. This is an improvement of approximately one order of magnitude compared to a previous measurement. The quoted value of the magnetic dipole moment includes corrections for the hyperfine structure anomaly and for diamagnetic shielding.     

New high-spin states of 147Nd and 145Ce: Octupole correlation in the N = 87 isotones

High-spin states of the N = 87 nuclei, ¹⁴⁷Nd and ¹⁴⁵Ce, have been populated in the ¹²C + ²³⁸U and ¹⁸O + ²⁰⁸Pb fusion-fission reactions at 90 MeV and 85 MeV bombarding energy, respectively. The emitted γ-radiation was detected using the Euroball III and IV arrays. High-spin states of the ¹⁴⁷Nd isotope have been identified for the first time. The high-spin yrast and near-to-yrast structures of the ¹⁴⁵Ce nucleus have been considerably extended. The newly observed structures, discussed by analogy with the neighbouring isotones, show the coupling of an h_9/2 neutron to the quadrupole and octupole excitations of the core.     

The g-factor and the electric quadrupole moment of the 7/2+ isomer in125Xe

The time differential perturbed angular distribution method (PAD) was used to measure theg-factor and the electric quadrupole interaction in a Cd single crystal for thet _1/2=140 ns,I ^π=7/2⁺ isomer in¹²⁵Xe. Theg-factor isg=+0.264(10) and the quadrupole coupling constante ² Qq/h=122.1 (6) MHz at 552 K. The lifetime of theI ^π=11/2⁺ state was measured to beτ=11.3 (1.1) ps by the recoil distance method (RDM). From an analysis of the spectroscopic data using the triaxial-rotor-plus-particle (TRPP) model the quadrupole moment of the 7/2⁺ isomer is deduced to beQ=1.40 (15) b yielding an electric field gradient (efg)eq=3.6(4)·10¹⁷ V/cm² for XeCd.     

The magnetic moment of the first 2+ state in22Ne

Theg-factor of the 1,275 keV 2⁺ state in²²Ne has been measured by means of the time-differential recoil-into-vacuum (plunger) technique. An analysis including excited heliumlike electronic configuration was performed. A fit, which includes all these electronic states, provides a value of ¦g¦=0.36±0.03.     

Reinvestigation of the high spin states in 《'161》Er and enhanced E1 transitions in the N=93 isotones

High-spin states in <'161>Er have been studied experimentally using the <'150>Nd(<'16>O, 5n) reaction at a beam energy of 86 MeV. The relatively enhanced E1 transitions between the 5/2<'+> [642] and 3/2<'-> [521] bands are observed in <'161>Er, and the B(E1) values are extracted experimentally. The systematics of the R(E1) values in the N = 93 isotones are presented. It is found that the strength of the E1 transitions obviously exhibits angular momentum dependence, and the occurrence of the relatively enhanced E1 transitions could be attributed to octupole softness.     

Excitation of ΔL = 0 spin-flip transitions in the N = 28 isotones by 201 MeV proton inelastic scattering

The effect of the three-nucleon forces on the triton binding energy (E_T) is investigated. Two different types of three-nucleon potentials are considered, one involving 2π-exchange (V_ππF) and the other involving 2σ-exchange (V_SSF) which is an approximation to 3π exchange. Both V_ππF and V_SSF are constructed using the πN scattering amplitude extrapolated to off (pion) mass shell subject to PCAC. The contribution of V_ππF and V_SSF to e_t are calculated in the first-order perturbation using the triton wave function obtained by solving the Faddeev equations with the Reid soft-core potential. The Fujita-Miyazawa force is also investigated as a special case. We find that the effect of V_ππF on E_T is sensitive to the assumed pionic form factor and is small due to cancellation between the πN s-d wave and p-wave contributions. The effect of V_SSF is also found to be small.     

Nonperturbative effects caused by the radiative component of the electron magnetic moment in hydrogen-like atoms

The lower levels of the discrete spectrum of a hydrogen-like atom are calculated within the point-like nucleus approximation with nonperturbative consideration for the Schwinger interaction of the radiative component of the magnetic moment of a free electron with the Coulomb field of a nucleus. The behavior of the 1s _1/2, 2s _1/2, 2p _1/2, and 2p _3/2 levels is investigated depending on the nuclear charge values, including the range of Z > 137, where the Dirac Hamiltonian continues to be self adjoint in the presence of the Schwinger term. It is shown that the Schwinger interaction for large Z causes significant changes in the properties of the discrete spectrum; in particular, the first level that reaches the threshold of a negative continuum is 2p _1/2 and this occurs at Z = 147. The behavior of the g-factor of an electron for the 1s _1/2 and 2p _1/2 states as a function of Z is considered as well and it is shown that for extremely large charges the correction to the g-factor due to the Schwinger term becomes a very significant effect.     

Half-life and magnetic moment of the 1+ first excited state in116Sb

The life-time and the magnetic dipole moment of the 1⁺ isomeric state in¹¹⁶Sb have been measured by the TDPAD method. The state was populated in the reaction¹¹⁶Sn(p, n)¹¹⁶Sb atE _p =15 MeV. The obtained results,μ(1⁺,¹¹⁶Sb)=+2.47(9) n.m. andT _1/2= 194(4) ns, support the pure single particle [πd _5/2*vd _3/2] configuration for the 1⁺ isomeric state.     

Measurement of transition quadrupole moments of high-spin states in the N=74 isotones Pr, Ce and La

The Doppler-Shift Attenuation Method has been used to extract transition quadrupole moments of high-spin bands in the N=74 isotones ¹³³Pr, ¹³²Ce and ¹³¹La, produced in the ³⁷Cl + ¹⁰⁰Mo reaction. The results appear to be configuration dependent and, for ¹³³Pr and ¹³²Ce, the involvement of Ω=1/2 νh_9/2 and νf_7/2 intruder orbitals appears to enhance the collectivity at high spin (I>25 ).     

Manifestation of the nuclear anapole moment in the thallium M1 transitions

We calculate the nuclear spin-dependent parity-nonconserving E1 amplitudes for the optical transition 6p _{1/2, F} →6p _{3/2, F′} and hyperfine transition 6p _{1/2, F} →6p _{1/2, F′} in ²⁰⁵Tl. The experimental limit placed upon the former amplitude by Vetter et al. [PRL 74, 2658 (1995)] corresponds to the anapole moment constant κ_a=?0.26±0.27.     

Theg-factor of the Iπ=5/2+ isomer in77Br

The g-factor of the t_1/2=9.3 ns, I_π=5/2 + state at E_x=130 keV in⁷⁷Br has been measured by observation of the time differential perturbed angular correlation (PAC) in a Co single crystal. The experimental value g=1.32(1) gives evidence for large deformation, which is discussed in the framework of triaxial-rotor-plus-particle models.     

Enhancement of two-proton transfer in N = 82 nuclei: A study of 1p, 2p and (2p+2n) transfer reactions induced by 16O on 140Ce, 142Nd and 144Sm near the Coulomb barrier

One-proton, two-proton, and α-particle transfer have been studied on nuclei with closed neutron shell N = 82 using ¹⁶O beams of 63 to 66.5 MeV incident energy. Transfer probabilities defined in a semiclassical model are derived for the different reaction channels. For this purpose the Q-value and angular dependence of the cross section are discussed. The two-proton transfer to the ground states shows an enhancement by a factor 20–25 compared to other nuclei, showing the effect of the proton pairing in these nuclei (they correspond to equivalent neutron configurations in ^{108, 110, 112}Sn). The total transfer probability follows a common trend for all three target nuclei as a function of energy above the Coulomb barrier for the proton and two-proton transfer, respectively, but not for the four-nucleon transfer.     

g-factor measurement of the two lowest 10+ states in 140Sm

The g-factors of the two 10⁺ states in ¹⁴⁰Sm at 3172 and 3210 keV have been measured by means of the TDPAD method. The obtained values are g = −0.176(20) and g = 1.27(9), respectively. The reaction ¹¹⁶Cd (²⁸Si, 4n)¹⁴⁰Sm, at incident beam energy of 125 MeV, has been used. The measured values clearly show that these states can be described as rather pure (νh_11/2)⁻² and (πh_11/2)² configurations.     

Magnetic moment of theI π=23/2− isomer in177Lu and additivity in the deformed region

^177g Lu and^177m Lu with half lives of 6.8d and 161d, respectively, were implanted into iron foils and oriented at low temperatures. From the temperature dependence of the anisotropies of severalγ-rays the magnetic moment of theI ^π=23/2^? three quasiparticle isomeric state^177m Lu was determined asμ=3.3±0.3 nm. It is shown that the additivity relation for magnetic moments is well fulfilled for four high spin multiparticle states in this mass region. Using the known magnetic moment of the ground state a value of ¦H¦=377±15 kG was derived for the internal field of Lu in Fe for our sample.