Tb Isotopes Research Articles

Electromagnetic isotope separation of gadolinium isotopes for the production of 152,155Tb for radiopharmaceutical applications

A demo experiment was performed at the tandem accelerator of MLL Garching where 152Tb was produced by irradiating a unique ion-implanted 152Gd target (>99% enriched) with 8 and 12 MeV protons respectively. At these energies mainly 152Tb was produced by (p,n) reactions plus a small quantity of 153Tb by (p,γ) reactions. Upper limits are derived for co-production of other Tb isotopes. The achieved radionuclidic purity would enable direct use for human applications. Gd isotopes of adequate isotopic enrichment could be separated with the SIDONIE mass separator at CSNSM Orsay and prepared as cyclotron targets suited for high current irradiations. In a demo experiment samples of highly enriched 158Gd were produced at SIDONIE. The sample purity was characterized by prompt gamma activation analysis at NPI Řež. The neighboring mass 157Gd was found to be suppressed by three to five orders of magnitude, depending on the sample position in the SIDONIE separator.

Extended investigation of superdeformed bands inTb151,152nuclei

A detailed study of known and new SD bands in Tb isotopes has been performed with the use of the EUROBALL IV gamma-ray array. The high-statistics data set has allowed for the extension of known SD bands at low and high spins by new gamma-ray transitions. These transitions, as it turns out, correspond to the rotational frequencies where the principal superdeformed gaps (Z=66,N=86) close giving rise to up- or down-bending mechanisms. This enables to attribute the underlying theoretical configurations with much higher confidence as compared to the previous identifications. Five new SD bands have been discovered, three of them assigned to the Tb-152 and the two others to the Tb-151 nuclei. Nuclear mean-field calculations have been used to interpret the structure of known SD bands as well as of the new ones in terms of nucleonic configurations.

Separation of carrier free 151,152Tb produced in 16O irradiated lanthanum oxide matrix

Charged particle activation of natural La 2O 3 with ∼78.5 MeV 16O results in the formation of carrier free 151,152Tb isotopes in the matrix. The liquid cation exchanger, HDEHP, has effectively been utilised as an extractant in the quantitative separation of the activation products from the bulk target matrix of lanthanum oxide.

Decay out of superdeformed bands in Tb isotopes

Excited states in the 150, 151, 152 Tb isotopes have been investigated using the 130Te(27 Al, xn) reaction and the EUROGAM array. The theoretical interpretation of the level schemes has been performed in the framework of the deformed independent particle model. The feeding patterns of the normal-deformed states by the superdeformed bands in 150, 151 Tb istopes have also been established. The results indicate that the decay-out mechanism of the bands is not of purely statistical nature, but depends on the configurations of both normal- and superdeformed states.

Electromagnetic moments and nuclear charge radii for neutron-deficient Tb isotopes and the deformation jump nearZ=64,N=90

Optical isotope shifts and hyperfine structures of the147–153,155,157,159 Tb isotopes have been measured by the resonance ionization spectroscopy method. Nuclear moments and changes in nuclear charge radiiΔ 〈r2〉 have been deduced. The “jump” inΔ 〈r2〉 atN=88–90 has been revealed. It is compared with the relevant data for nuclei with other proton numbers.

Laser photoionization spectroscopy of rare-earth elements: New results on nuclear electromagnetic moments and charge radii of Eu, Gd and Tb isotopes

New results on spins, electromagnetic moments and isotopic changes of nuclear charge radii for 63 157–159 Eu, 64 146, 148, 150 Cd and 65 147–155, 157, 159 Tb have been obtained from hyperfine structure and isotope shifte measured with laser resonance photoionization technique. These results complement two-dimensional picture (with respect to H and Z) of the changes of nuclear ground state properties near the “critical” neutron numbers N=88–90 in the vicinity of the “magric” proten number Z=64.

Decay studies of neutron-deficient nuclei near the Z=64 subshell: 141Dy, 141Tb, 141Gdg+m, and 141Eum.

The {beta}/{gamma} and delayed proton decays of mass separated {ital A}=141 isotopes with {ital Z}=63--66 were investigated with an on-line mass separator. Branching ratios have been redetermined for the total {beta} decay of the 2.7(3) s, (11/2){sup {minus}} isomer {sup 141}Eu{sup {ital m}} at 96.5 keV (13{sub {minus}2}{sup +4}%), and for the direct {beta} feeding of the 1.58 keV (3/2){sup +} level of {sup 141}Sm in the decay of 40-s {sup 141}Eu{sup {ital g}} (73(5)%). Detailed decay schemes have been constructed for the decays of the (11/2){sup {minus}} isomer {sup 141}Gd{sup {ital m}} (11(2)% isomeric transition) and the (1/2){sup +} ground state, {sup 141}Gd{sup {ital g}}. Half-lives of 24.5(5) s and 14(4) s, respectively, have been determined for these isomers. A delayed proton branch of 0.03(1)% was identified in the decay of {sup 141}Gd{sup {ital g}}. A detailed decay scheme was also constructed for 3.5(2)-s {sup 141}Tb and a {ital J}{sup {pi}}=(5/2{sup {minus}} ) was assigned to its ground state, at variance with the systematics of heavier, odd-mass Tb isotopes. All {gamma}-ray assignments to the various isotopes are based on {ital x}{gamma} and {gamma}{gamma} coincidences and on half-life measurements. A 0.9(2)-s half-life for {sup 141}Dy was determined from its delayedmore » proton decay. All spin assignments proposed in this paper are discussed in terms of Nilsson level diagrams and nuclear shapes.« less

On the role of the coriolis and quasiparticle-phonon interactions in describingE1 transition probabilities in odd Eu and Tb isotopes

It is shown within the microscopic approach combining the quasiparticle-phonon nuclear model and the nonadiabatic rotational model (QPNM + NRM) that a complicated behaviour of E1 transitions in nuclei153,155Eu and155,157Tb can be described only if both the Coriolis and quasiparticle-phonon interactions are taken into account. In contrast with the results obtained in the NRM allowing for pairing and the Coriolis forces only, QPNM + NRM calculations provide a considerable increase inE1(ΔK=0) transitions whereasE1(¦ΔK¦=1) transitions can undergo either increase or essential decrease. We also describe the low-lying states of the considered nuclei and demonstrate the decisive role of the giant dipole resonance “tail” inE1 transitions between the low-lying states. The obtained results are analysed in detail.

Low-temperature nuclear orientation of neutron-deficient terbium nuclei

152,153,154m1,154m2,156,160Tb isotopes have been oriented in a gadolinium matrix at low temperature. A new nuclear thermometer and a consistent evaluation procedure have been developed. The following nuclear moments are derived from the measurements. 156Tb(3-): mod mu mod =1.68(21) mu N, Q=+1.9(7) b; 154Tbm1(3-); mod mu mod =1.8(39) mu N, Q=+2.4(13) b; 153Tb(5/2+): mod mu mod =3.5(7) mu N; 152Tb(2-): mod mu mod =0.60(44) mu N, Q=+0.4(14) b. Using a reasonable approximation for the electric quadrupole moments mod mu (152Tb; 2- mod =0.9(1) mu N and mod mu (154Tbm2(7-) mod =0.9(3) mu N are obtained. The magnetic moments of the odd-odd nuclei allow their proton and neutron configurations to be determined. Experimental magnetic moments are confronted with rotor+quasiparticle calculations involving Coriolis mixing. Reduced electromagnetic transition probabilities are compared with rotational-model calculations using the measured static electromagnetic moments.

Yrast Octupole Excitations in the 146Gd Region

Octupole excitations frequently occur in the yrast lines of nuclei above 146Gd. One-particle phonon exchange coupling identified in the Tb isotopes gives rise to low-lying ΔI = 2 octupole excitations; two-particle phonon exchange coupling in Dy isotopes causes ΔI = 1 octupole excitations in the yrast lines above 3 MeV which deexcite by E1 transitions of ≃ 1 MeV. The predominant octupole nature of the low-lying 13/2+ states in the N = 83 nuclei is emphasized, and the two-phonon octupole character of a 19/2- level in 147Gd which decays by E3 to the 13/2+ (νf7/2 × 3-) state is discussed.

Self-consistent quasiparticle-phonon coupling calculations for deformed superfluid nuclei in the rare earth region

The self-consistent quasiparticle-phonon coupling equations are solved for deformed superfluid nuclei in the rare earth region. Parameters are chosen to agree with previous calculations, and the solutions for $\ensuremath{\gamma}$-, $\ensuremath{\beta}$-, and octupole-vibrational states are compared to experiments and to previous descriptions of both even- and oddmass nuclei. The importance of exclusion principle violations in the rare earth region is noted as well as the interference of pairing and quadrupole correlations in the even nuclei with $A\ensuremath{\sim}164$. An "intruder" state is predicted in the Eu and Tb isotopes. The splitting of the $K\ifmmode\pm\else\textpm\fi{}2$ states in $^{165}\mathrm{Ho}$ and $^{167}\mathrm{Er}$ is derived from higher-order contributions to the self-energy.NUCLEAR THEORY Green's function method with pairing. Self-consistent RPA, collective effects in odd-$H$ rare earth nuclei.

Separation and pairing energies involving isotopes of Tb, Dy, Ho, Er, Tm, Yb, Lu and Hf

Abstract Fifteen new atomic mass difference determinations are combined with a large body of reaction and decay data in a recalculation of the separation and pairing energies for Hf and the heavier rare earth nuclei. The accuracy and reliability of the data are such that definite systematic trends are observed. The data have also allowed the accurate determination of three decay Q -values which were previously unknown.

Existence of a New Isomer of T1/2=24.4 hr in 156Tb

A new transition of 49.630±0.010 keV decaying with a half-life of 24.4±1.0 hr was found in 156 Tb. The isotope assignment was made by the energies of L- and M-subshell internal conversions and the mass assignment by yield ratios of various Tb isotopes at different bombarding energies. The multipolarity of the transition is determined to be E1 from the L-subshell ratios. The decay scheme concerning this new transition is unknown yet.

The ∥ ΔK∥ = 1, E1 transitions in odd-mass isotopes of Tb and Eu

Lifetime measurements have been performed for the 5 2 − [532] intrinsic state in the Tb isotopes with A = 155, 157, 159 and 161. The rates of the ∥ ΔK∥ = 1, E1 transitions in these isotopes, as well as in 153Eu and 155Eu, are discussed. With the Nilsson model as a starting point, the effects of pairing correlations and Coriolis coupling are calculated. It is found that these effects are not sufficient to account for the essential features of the experimental results. It is suggested that dipole contributions arising through octupole excitations are of importance.

Alpha-Emitting Isomeric State ofTb149

Bombardment of La/sup 139/ targets with 80- to 140-Mev O/sup 16/ ions resulted in the identification of a new alpha activity decaying with a half-life of 4.3 plus or minus 0.2 min and an alpha energy of 3.99 plus or minus 0.03 Mev. The activity was due to an isomeric state of Tb/sup 149/. lt was proposed that the isomerism was caused by the filling of an h/sub 11/2, proton state for the spherical Tb isotopes. (auth)

Nuclear Spectroscopy of Odd-Mass (161-173) Nuclides Produced by Proton Irradiation of Er and Yb

To study the effect of nucleon number on nuclear levels of odd-mass rare-earth isotopes, enriched isotopes of Er and Yb were irradiated with protons in the ORNL 86-inch Cyclotron. After chemical separation, the decay chains leading to stable isotopes were analyzed with internal-conversion, photographic-recording, permanent-magnet spectrographs. Precise energy values as well as photometrically measured intensities of conversion lines of 8 to 1600 kev energy were obtained. Very light isotopes of Lu and Tm, each eight mass units from the mass stability line, were produced. The following activities were studied: ${\mathrm{Tm}}^{161}$, (\ensuremath{\sim}30 min), ${\mathrm{Ho}}^{161m}$ ($E3$, 211 kev), ${\mathrm{Tm}}^{163}$ (2 hr), and ${\mathrm{Lu}}^{167}$ (54 min), all previously unreported, as well as ${\mathrm{Tb}}^{161}$, ${\mathrm{Ho}}^{161}$, ${\mathrm{Tm}}^{165,167}$, ${\mathrm{Yb}}^{167}$, ${\mathrm{Lu}}^{169,171,173}$, ${\mathrm{Hf}}^{173}$, and possibly ${\mathrm{Yb}}^{169m}$. Genetic relationships and partial level schemes for decay chains of masses 151 to 173 are shown. Where comparison is possible, excellent agreement with the predictions of Mottelson and Nilsson is obtained, particularly for the case of the various isotopes of Tb ($Z=65$), Ho ($Z=67$), and Tm ($Z=69$), where striking similarities in the level structure are observed.

Some New Radioactive Isotopes of Tb, Ho, Tm, Lu, Ta, W, and Re

Some New Radioactive Isotopes of Tb, Ho, Tm, Lu, Ta, W, and Re