Rare-earth Isotopes Research Articles

Cross sections from 800 MeV proton irradiation of terbium

A single terbium foil was irradiated with 800 MeV protons to ascertain the potential for production of lanthanide isotopes of interest in medical, astrophysical, and basic science research and to contribute to nuclear data repositories. Isotopes produced in the foil were quantified by gamma spectroscopy. Cross sections for 36 isotopes produced in the irradiation are reported and compared with predictions by the MCNP6 transport code using the CEM03.03, Bertini, and INCL+ABLA event generators. Our results indicate the need to accurately consider fission and fragmentation of relatively light target nuclei like terbium in the modeling of nuclear reactions at 800 MeV. The predictive power of the code was found to be different for each event generator tested but was satisfactory for most of the product yields in the mass region where spallation reactions dominate. However, none of the event generators' results are in complete agreement with measured data.

Samarium-Neodymium and Strontium Systematics Applied to Calcite Veins in Dabashan Thrust and Fold Belt in China: Dating and Tracing of the Fluid

Dabashan Thrust and Fold Belt is situated in the transfer zone between Qinling Orogen and Sichuan Basin, where multi-generation calcite veins were developed. Two kinds of veins, bedding-parallel and fracture-filled veins, were collected for analyses of rare-earth elements (REE), samarium-neodymium and strontium isotopes. The total REE contents of the calcites from the bedding-parallel vein are much higher than those from fracture-filled veins and are rich in light REE (LREE). The chondrite-normalized patterns of REE curves of the calcites from fracture-filled veins are flatten. The 87Sr/86Sr and 143Nd/144Nd ratios of calcites from bedding-parallel vein are from 0.71068 to 0.71115 and from 0.51192 to 0.512058, respectively. On the 147Sm/143Nd vs 143Nd/144Nd diagram, the six samples from the bedding-parallel vein give a Sm-Nd isochron age of 357±230 Ma (2σ)( MSWD = 24) with an initial 143Nd/144Nd ratio of 0.51168±0.00019. However, the plots of the four samples from fracture-filled veins are rather scatter either on 147Sm/143Nd vs 143Nd/144Nd or on 87Sr/86Sr vs 143Nd/144Nd diagram. The fluids, from which the two kinds of veins precipitated, are different in origin and flowing.

Synthesis of a Functional Metal-Chelating Polymer and Steps toward Quantitative Mass Cytometry Bioassays

We describe the synthesis and characterization of metal-chelating polymers with a degree of polymerization of 67 and 79, high diethylenetriaminepentaacetic acid (DTPA) functionality, M(w)/M(n) ≤ 1.17, and a maleimide as an orthogonal functional group for conjugation to antibodies. The polymeric disulfide form of the DP(n) = 79 DTPA polymer was analyzed by thermogravimetric analysis to determine moisture and sodium-ion content and by isothermal titration calorimetry (ITC) to determine the Gd(3+) binding capacity. These results showed each chain binds 68 ± 7 Gd(3+) per chain. Secondary goat antimouse IgG was covalently labeled with the maleimide form of the DTPA polymer (DP(n) = 79) carrying (159)Tb. Conventional ICPMS analysis of this conjugate showed each antibody carried an average of 161 ± 4 (159)Tb atoms. This result was combined with the ITC result to show there are an average of 2.4 ± 0.3 polymer chains attached to each antibody. Eleven monoclonal primary antibodies were labeled with different lanthanide isotopes using the same labeling methodology. Single cell analysis of whole umbilical cord blood stained with a mixture of 11 metal-tagged antibodies was performed by mass cytometry.

REE characteristics and Nd isotopic compositions of Lunar pristine rocks: Implications for petrogenesis of pristine rocks and source regions

This paper compile the rare-earth elements and Nd isotope data for lunar pristine rocks from investigations in recent years. Using these data, we compared the REE characteristics of lunar pristine rocks and Nd isotopic compositions of their source regions. Based on the Lunar Magma Ocean model, we then studied their formation and petrogenetic correlations of Mg suite, alkali suite, and KREEP, with especial emphasis on the importance of assimilation during early magmatism. And Nd isotopic compositions of mare basalt samples suggest that mantle sources of mare basalts should be heterogeneous, which has not yet been explained by several current models.

Angular correlation studies on 172Lu(172Yb) in GaN and measurements at low temperatures

For optoelectronic devices semiconductors with large band gap doped with rare earth are used. Doping is generally performed during growth but for more structured doping the ion implantation technique is preferable. The perturbed γγ-angular correlation technique is an ideal tool to study the behavior of semiconductors after implantation. An adequate rare earth isotope for such investigations of semiconductors is 172Yb. The temperature dependence of the hyperfine fields for 172Lu(172Yb) in GaN has been analysed. The total electric field gradient (EFG) at the site of this probe is a superposition of the lattice EFG due to the GaN wurtzite structure and the EFG due to the 4f shell of the rare earth probe itself. The latter is strongly temperature dependent and opposed to the lattice EFG which in contrast is nearly constant since the lattice parameters change only negligibly with temperature. At elevated temperatures the sublevels of the 4f shell, split by the crystal electric field, are equally populated. But at low temperatures the lowest level is occupied preferentially. Sign and magnitude of the EFG caused by the 4f shell can be calculated (Tomala et al, J Magn Magn Mater 89(1–2):143, 1990) and the result compared to the experimental data.

Simple method for transportation and storage of rare earths or similar isotopic materials in vacuum or inert gas

The rare earth isotopes are mostly delivered in the form of oxides. Sometimes, after the reduction procedure, not all metal is used immediately and often excess of the rolled foil or the scraps is left over. The remains may be used in future in case they are properly preserved. In order to avoid oxidation, a method of storage in quartz tube under vacuum is described. One can apply the similar solution for transportation of sensitive targets. This paper describes the procedure and the equipment for sealing, storage or transportation of rare-earth metal foils in vacuum or inert-gas atmosphere. The described solution is appropriate for isotopes, which can be exposed to air for a short time without significant oxidation damage. The procedure can also be applied for storage in low-pressure inert-gas atmosphere like argon (below atmospheric pressure).

Muon spectroscopy with trace alkaline-earth and rare-earth isotopes implanted in solid D2

New intense muon beams with flux several orders of magnitude higher than at present muon facilities would allow many novel experimental studies that were until now statistically not feasible. The investigation of the nuclear properties of short-lived nuclei using muonic atom spectroscopy would become possible. A feasibility study at RIKEN-RAL muon facility using the cold hydrogen film method to produce radioactive muonic atoms is in progress. A new surface ionization type ion source was recently installed to expand the variety of available ions. Encouraging experimental results were obtained with stable alkaline-earth and rare-earth isotope ions implanted in solid deuterium films. The latest results are reported in this paper.

Determination of 151Sm and 147Pm using liquid scintillation tracer methods

The long-lived rare earth isotopes 151Sm (90 years, βmax = 76.3 keV) and 147Pm (2.62 years, βmax = 224.6 keV) are low-yield fission products that generally require lengthy separation procedures to isolate and count by their beta emissions. We will describe novel liquid scintillation counting techniques using radioactive tracers to determine radiochemical yields from an environmental matrix. The recovery of 151Sm is determined from the alpha decay (2.25 MeV) of 147Sm in the natural Sm carrier and is in excellent agreement with the gravimetric recovery. The 147Pm recovery is determined by the use of 145Pm (17.7 years, EC) tracer, custom-produced at LANL using an isotopically enriched target of 144Sm. We have determined the 145Pm recovery both from the 37.4 keV kα1 X-ray, and the electron-capture emissions by LSC. A comparison of these recovery methods is presented.

Description of the dipole giant resonance in heavy and superheavy nuclei within Skyrme random-phase approximation

The $E1(T=1)$ isovector dipole giant resonance (GDR) in heavy and superheavy deformed nuclei is analyzed over a sample of 18 rare-earth nuclei, four actinides, and three chains of superheavy elements ($Z=102$, 114, and 120). The basis of the description is the self-consistent separable random-phase approximation (SRPA) using the Skyrme force SLy6. The model well reproduces the experimental data in the rare-earth and actinide regions. The trend of the resonance peak energies follows the estimates from collective models, showing a bias to the volume mode for the rare-earth isotopes and a mix of volume and surface modes for actinides and superheavy elements. The widths of the GDR are mainly determined by the Landau fragmentation, which in turn is found to be strongly influenced by deformation. A deformation splitting of the GDR can contribute to about one-third of the width, and about 1 MeV further broadening can be associated with mechanisms beyond the SRPA description (e.g., escape widths and coupling with complex configurations).

ON SENSING NUCLEI OF THE LANTHANIDE ISOTOPES BY MEANS OF LASER SPECTROSCOPY OF HYPERFINE STRUCTURE: 165Ho, 169Tm

It is presented the effective theoretical scheme with possibility of advancing corresponding nuclear technology for sensing different parameters for nuclei of the lanthanide isotopes. As example, the nuclei of elements 165Ho and 169Tm are considered.

Effect of Microorganisms on the Sorption of Lanthanides by Quartz and Goethite at the Different pH Values

The effect of Rhodopseudomonas pallustris bacterium on the sorption of 16 isotopes of lanthanides by quartz and goethite at different pHs values was studied. pH of sorption solution and affinity of elements to surface seems to be most important parameters in the interactions between metal ions and surfaces of biological and mineral sorbents. At acidic (pH°4) and neutral (pH°7) conditions these interactions was affected by electrostatic forces; at alkaline conditions (pH°9) the mechanism of lanthanides precipitation was dominant. Microorganisms sufficiently affected on lanthanides sorption by quartz at acidic and neutral conditions, but largest one was at pH°7. They increased sorption of all elements by goethite at pH°4. There was negligible effect of bacteria on the sorption of lanthanides at pH°7 and 9 by goethite that demonstrates greater affinity of the elements to goethite surface. Microorganisms increased concentration of lanthanides in the nonexchangeable states on the surfaces of quartz at pH°7 and 9, and on the surface of goethite at pH°7 in comparison to the minerals alone. It may be attributed to formation of low-soluble complexes of lanthanides with organic substances, produced by bacterium.

Comparison of the analytical sensitivities for non-1/v elements in different neutron beams

Irregular nuclides such as 113Cd, and some rare-earth isotopes show different analytical sensitivities in PGAA performed at different facilities, because the cross-sections of these nuclides have strong low-energy resonances which partly overlap the energy range of typical neutron beams used for activation. A series of systematic measurements has been performed in the spectrally different cold and thermal neutron beams of the Budapest Research Reactor, Hungary and at the research reactor of NIST, Gaithersburg, USA to quantitatively study the non-1/v behaviour of irregular nuclides. Samples were prepared that contained one of the irregular nuclides and also a regular one (10B, 35Cl and 56Fe) and their activation ratios were compared as measured in five different beams. Theoretical values of the activation ratios were calculated from estimates of the actual neutron spectra and cross-section data, and show a generally good correspondence to the experimental results, although some details are still not reproduced.

Spectral interferences from polyatomic barium ions in inductively coupled plasma mass spectrometry

For the Element2 (a relatively new high-sensitivity magnetic sector ICP MS), we have studied spectral interferences from barium arising as a result of polyatomic barium ions, which have a considerable effect on the intensity of lines for rare-earth isotopes. We have shown that the parameters characterizing the interferences (the ratios of the signals from oxygen-containing, chlorine-containing, and fluorine-containing BaX+ ions to the Ba+ signal, and the apparent rare-earth concentrations Capp j resulting when overlap from polyatomic Ba occurs) are higher for the Element2 than for a quadrupole instrument (PQ2+). However, it is possible to solve many spectral overlap problems when using the Element2 by using the medium-resolution (MR) or high-resolution (HR) modes. We have estimated the resolutions needed to completely separate the masses of the polyatomic barium ions and the rare-earth isotopes in the spectrum. For cases when it is impossible to use the high-resolution mode due to the ∼100-fold decrease in sensitivity, we recommend preliminary separation of Ba from the rare earths. In this work, we have used extraction chromatography to determine low rare-earth concentration levels in Lake Baikal water.

Determination of stability constants of lanthanide nitrate complex formation using a solvent extraction technique

Summary For lanthanides and actinides, nitrate complex formation is an important factor with respect to the reprocessing of nuclear fuels and in studies that treat partitioning and transmutation/conditioning. Different techniques, including microcalorimetry, various kinds of spectroscopy, ion-exchange and solvent extraction, can be used to determine stability constants of nitrate complex formation. However, it is uncommon that all lanthanides are studied at the same time, using the same experimental conditions and technique. The strengths of the complexes are different for lanthanides and actinides, a feature that may assist in the separation of the two groups. This paper deals with nitrate complex formation of lanthanides using a solvent extraction technique. Trace amounts of radioactive isotopes of lanthanides were produced at the TRIGA Mainz research reactor and at the Institutt for Energiteknikk in Kjeller, Norway (JEEP II reactor). The extraction of lanthanide ions into an organic phase consisting of 2,6-bis-(benzoxazolyl)-4-dodecyloxylpyridine, 2-bromodecanoic acid and tert-butyl benzene as a function of nitrate ion concentration in the aqueous phase was studied in order to estimate the stability constants of nitrate complex formation. When the nitrate ion concentration is increased in the aqueous phase, the nitrate complex formation starts to compete with the extraction of metal ions. Thus the stability constants of nitrate complex formation can be estimated by measuring the decrease in extraction and successive fitting of an appropriate model. Extraction curves for La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Dy, Ho and Er were obtained and stability constants for their nitrate complex formation were estimated. Tb, Tm, Yb and Lu were also investigated, but no stability constants could be determined. The distribution ratios for the metal ions at low nitrate ion concentration were obtained at the same time, showing the effect of lanthanide contraction resulting in decreasing extraction along the series. A clear tetrad effect in the lanthanide group was also found.

Laser mass spectrometric studies on rare earth doped UO 2

A laser mass spectrometry system comprising of in-house developed reflectron time-of-flight mass spectrometer was used to study solid and liquid samples containing UO 2 doped with lighter rare earths (La, Ce, Sm and Nd). Unit mass resolution is obtained for all the rare earth isotopes. Preliminary results indicate that this method has potential for direct determination of burnup of irradiated nuclear fuel.

Laser Ablation and Solution ICP-MS Determination of Rare Earth Elements in USGS BIR-1G, BHVO-2G and BCR-2G Glass Reference Materials

Data are reported for rare earth elements (REE) in three geological glass reference materials (BIR-1G, BHVO-2G and BCR-2G) using a UV (266 nm) laser ablation ICP-MS system and the classical (HF-HClO4) acid decomposition method, followed by conventional nebulisation ICP-MS. External calibration of laser ablation analyses was performed using NIST SRM reference materials with internal standardisation using 29Si and 44Ca. Replicate analyses of reference basaltic glasses yielded an analytical precision of 1-5% (RSD) for all the elements by solution ICP-MS and 1-8% (RSD) by laser ablation ICP-MS. The relative differences between the REE concentrations measured by solution and laser ablation ICP-MS compared with the reference values were generally less than 11 % for most elements. The largest deviations occurred for La determined by solution ICP-MS in BIR-1G. The results of both solution and laser ablation ICP-MS agreed well, generally better than 7%, with the exception of La, Pr and Sm in BIR-1G. The measured REE laser ablation data for BIR-1G, BHVO-2G and BCR-2G agreed with the previously published data on these basaltic reference glasses, within a range of 0-10% for most elements. No significant influences were observed for the predicted spectral interferences on some REE isotopes in the analysis of basaltic glasses.

β-decay half-lives of new neutron-rich rare-earth isotopesPm159,Sm162, andGd166

The new neutron-rich rare-earth isotopes $^{159}\mathrm{Pm}$, $^{162}\mathrm{Sm}$, and $^{166}\mathrm{Gd}$ produced in the proton-induced fission of $^{238}\mathrm{U}$ were identified using the JAERI on-line isotope separator (JAERI-ISOL) coupled to a gas-jet transport system. The half-lives of $^{159}\mathrm{Pm}$, $^{162}\mathrm{Sm}$, and $^{166}\mathrm{Gd}$ were determined to be 1.5 \ifmmode\pm\else\textpm\fi{} 0.2, 2.4 \ifmmode\pm\else\textpm\fi{} 0.5, and 4.8 \ifmmode\pm\else\textpm\fi{} 1.0 s respectively. The partial decay scheme of $^{166}\mathrm{Gd}$ was constructed from $\ensuremath{\gamma}\ensuremath{\gamma}$-coincidence data. A more accurate half-life value of 25.6 \ifmmode\pm\else\textpm\fi{} 2.2 s was obtained for the previously identified isotope $^{166}\mathrm{Tb}$. The half-lives measured in the present study are in good agreement with the theoretical predictions calculated by the second generation of the gross theory with the atomic masses evaluated by Audi and Wapstra.

The Rare Earth PAC Probe 172Lu in Wide Band-Gap Semiconductors

Group III nitrides and other wide band-gap semiconductors like ZnO are very promising materials for application in optoelectronics. However, little is known about the recovery of lattice damage caused by ion implantation necessary to achieve lateral structuring. We use the PAC technique to study the behaviour of the Rare Earth isotope 172Lu(172Yb) after implantation. After annealing, a large fraction of the probes is found on unique lattice sites with axial symmetry and a low damping of the interaction frequency. In addition the corresponding electric field gradient is aligned along the axis. A substitutional incorporation of the Rare Earth on regular metal lattice sites is therefore probable.

Geochemistry, Geochronology and Genesis of Gold Mineralization in Nurt of Northern Altay, Xinjiang: A Case Study on the Aketishikan Gold Deposit

Abstract Gold deposits such as the Aketishikan, Togetobie, Tasbig‐Kokeydlas, Kums and Hongshanzui gold deposits in the Nurt area in Altay of Xinjiang were found in Member 3 rhyolite tufflava, fragmental lava and ignimbrite of the Carboniferous Hongshanzui Group. Trace and rare earth elements, sulfur, lead, oxygen and hydrogen isotopes, and geochronological studies indicate that the ore‐forming material was mostly supplied by the Carboniferous volcanic rocks through water‐rock interaction under a low‐to‐moderate temperature, and the hydrothermal ore‐forming fluid came from meteoric water with some magmatic water input evolved from the granitic magmas. Gold deposits in the Nurt area as well as in the northern Altay might form in multiple stages, and the Yanshanian mineralization period should be paid more attention besides the Variscan mineralization period.

Cross section measurements for (n, p) and (n, 2n) reactions of rare-earth isotopes at neutron energies from 13.5 to 14.6 MeV

Cross sections for (n, p) and (n, 2n) reactions have been measured on some rare-earth isotopes at neutron energies of 13.5-14.6 MeV using activation technique. Data are reported for the following reactions:150Nd(n, 2n) 149Nd, 148Nd(n, 2n) 147Nd, 142Nd(n, 2n) 141Nd, 160Gd(n, 2n) 159Gd, 158Gd(n, p) 158Eu, 146Nd(n, p) 146Pr, 141Pr(n, p) 141Ce and 139La(n, p) 139Ba. The neutron fluences are determined by the cross sections of 27Al(n, a) 24Na and 93Nb(n, 2n) 92mNb reactions.