Natural Tantalum Research Articles

Trace-scale extraction of carrier-free tungsten radioisotope as a homolog of Sg using ionic liquid from acid solutions: Kinetic study

This study aimed to find a rapid extraction system for the preparation of a Seaborgium (Sg) aqueous chemistry experiment in the future. A new approach for extraction of 181W tracer as a lighter homolog of (Sg) by ionic liquids is explored. A natural tantalum target was activated by a beam of 9 MeV proton at Cologne University to produce carrier-free 181W. The preliminary batch extraction experiments of the carrier-free 181W from HCl and H2SO4 solutions have been evaluated. Different batch extraction parameters such as feed acidity, diluent type, ionic strength (KCl feed) and reducing agent as a function of time were explored. The obtained results demonstrated that the highest distribution of carrier-free 181W from 0.001 M acidic solutions using the used ionic liquid is observed. A significant rapid kinetic for the extraction of trace-scale using the used ionic liquid is achieved within 5 sec. The preliminary results are necessary to design the upcoming aqueous experiments of Sg. The next goal will be on-line experiments with the centrifuge system SISAK to develop the aqueous chemistry extraction of Sg using the most promising and adequate experimental setup.

Investigation of (γ,α) Reactions on Natural Tantalum

The study presents the results of the yield analysis of a promising medical radioisotope 177Lu in (γ,α) reactions upon irradiation of natural tantalum with electron bremsstrahlung with boundary energies of 37, 40, and 55 MeV. The experimental yields are compared with the results of calculations based on the collective model of the nucleus. The isomeric ratio of the yield for 177mgLu was determined.

Activation cross section measurement of alpha-particle induced nuclear reactions on tantalum

Activation cross sections induced by 50 MeV alpha-particle beam on natural tantalum were measured at the AVF cyclotron of the Nishina Center of RIKEN. The well-established stacked target technique and activation method were applied followed by high-resolution gamma spectrometry to determine the reaction cross sections. The experiment aimed to determine activation cross sections for the longer-lived reaction product. Accordingly, activation cross sections were deduced for the formation of 181, 182m, 182g, 183, 184m, 184gRe and 178g, 182gTa.

Feasibility Study on Production of High-Purity Rhenium-185 by Nuclear Transmutation of Natural Tantalum

Rhenium-186 (Re-186) has attracted attention as a medical isotope. The feasibility of producing Re-185, the raw material for Re-186, using a fast reactor was evaluated using a continuous energy Monte Carlo code. The irradiation of natural tantalum (Ta) in the fast reactor can produce Re-185 with an isotopic purity of 99%. A two-step irradiation process with different moderators was found to improve the production rate of Re-185. Specifically, this can be achieved by using zirconium hydride (ZrH1.7) as a moderator in the first transmutation process from natural Ta to tungsten (W), and then zirconium deuteride (ZrD1.7) as a moderator in the second transmutation process from W to Re-185. Due to the two-step irradiation, the production rate of Re-185 from Ta can be increased up to a maximum of 470 times compared with irradiation without a moderator, and 2.3 g of Re-185 can be obtained from 1571 g of Ta in 1 year of irradiation. The proposed isotope production method is a new method that is different from the conventional electromagnetic enrichment process.

178m2Hf isomer production cross-sections for Ta target irradiated by α-particles in the energy range from 36 to 92 MeV

178m2Hf isomer production cross-sections were measured when natural tantalum targets were irradiated by alpha particles in the energy range of 36–92 MeV. The simulations of these cross-sections in the TALYS-1.4 code showed that the main contribution to the 178m2Hf isomer production is given by (α, αp2n), (α, 3p4n) and (α, 3Hep3n) nuclear reactions. In the range of α-particle energies of 58–92 MeV, the theoretical results coincided well with the experimental ones, and based on this, the cross-sections of the 178gHf ground state production were estimated. allowing to calculate the isomer ratios as well. The obtained values are in good agreement with the trend of changes for the isomer ratios obtained in the nuclear reactions with lower-energy alpha particles and other targets.

Production cross-section measurements of proton-induced reactions on natural tantalum in the 0.3 GeV–1.7 GeV energy range

This work reports the production cross-section data for seventy-one radionuclides produced by 0.3 GeV–1.7 GeV protons impinging on thin tantalum targets. For that purpose, activation experiments were performed using the COSY synchrotron at FZ Jülich utilizing the stacked-foils technique and γ-ray spectrometry with high-purity germanium detectors. The Al-27(p,x)Na-24 reaction has been used as monitor reaction. All experimental data have been systematically compared with the existing literature. The excitation functions of Te-116, I-123, Dy-153 and Er-158 are reported for the first time.

The activation cross section measurements of proton-induced reactions on Li and Ta in the energy region 12.5–34 MeV

The experimental data on cross sections are necessary to clarify existing ideas on the mechanisms of nuclear reactions and for testing of nuclear models. Proton-induced reaction on 7Li serves as a source of quasi-monoenergetic neutrons which are widely used in the measurement of cross sections for neutron induced reactions. Tantalum plays an important role in technology and nuclear facilities mainly for its low induced activity (screens, degraders). In order to investigate the important nuclides, we have carried out the irradiation experiments with the variable-energy cyclotron U-120M of the NPI CAS Řež. The cross section of the reaction 7Li(p,n)7Be(ground state+0.43 MeV) and the cross sections of the nuclides 180,178mTa, 178W and 175Hf from reactions on natural tantalum were investigated, of which 181Ta(p,n)180gTa for the first time. The stacked-foil technique was utilized. The comparison of new results with prior data and predictions of evaluations is discussed.

Exploratory study of the 180mTa(γ,γ′)180Ta reaction with mono-energetic low-energy photon beams at HIγS

Abstract For the first time the de-excitation cross section of the isomeric-state nuclide 180 m Ta has been measured with mono-energetic photon beams in the 1.56 MeV to 3.70 MeV energy range. The measurement of this inelastic scattering cross section on nature’s rarest isotope was performed at eight energies at the High-Intensity Gamma-Ray Source Facility with natural tantalum targets. After irradiation for typically 20 h with photon fluxes ranging from 0 . 3 × 1 0 7 γ /( cm 2 × s) to 3 . 2 × 1 0 7 γ /( cm 2 × s), the 180 m Ta de-excitation cross section was obtained from the yield of the K α 1 and K α 2 X rays of 180 m Hf at 55.79 keV and 54.61 keV, respectively, produced after electron capture on the unstable 180 m Ta ground state. The cross-section values found vary between ( 2 . 0 ± 0 . 7 ) mb and ( 4 . 7 ± 1 . 5 ) mb, providing a very large cross section for the de-excitation of 180 m Ta. Extensive tests were performed to check on the reliability of the present data. The effect of bremsstrahlung photons of higher energy than the mono-energetic beam was carefully studied and corrected for. It was found that even a very small contamination of the mono-energetic photon beam by bremsstrahlung photons with E γ > 7 . 6 MeV can provide a sizable yield of 180 m Hf X rays via the reaction 181 Ta ( γ , n ) 180 Ta, if a natural tantalum target is used, which contain four orders of magnitude more 181 Ta nuclei than 180 m Ta nuclei available for the 180 m Ta ( γ , γ ′ ) 180 Ta reaction of interest.

46-MeV 전자선형가속기의 TOF 방법을 이용한 탄탈의 중성자 공명 에너지 분석에 관한 연구

Neutron sources from photonuclear reaction with 46-MeV electron linear accelerator at Research Reactor Institute, Kyoto University used for resonance energy measurement of natural tantalum. BGO() scintillation detectors used for measurement of the prompt gamma ray from the natural tantalum sample. The BGO spectrometer was composed geometrically as total energy absorption detector. The electric signal from the spectrometer was analyzed for TOF(Time-of-Flight) spectrum which is used identification of neutron capture resonance energy. In this study, the neutron energy region is from 1 to 200 eV, because of strong X-ray effect produced photonuclear reaction in Ta target, the measurement was performed to below 1 keV energy region. The resonance energy was compared with the evaluated values(ENDF/B-VI, Mughabghab). All of the resonances from 4.28 ~ 200 eV were seen in the present measurement except 144.3 eV resonance.

Application of PEG based aqueous biphasic systems in extraction and separation of no-carrier-added 183Re from bulk tantalum

Abstract No-carrier-added (nca) rhenium isotopes (182,182m,183Re) were produced by irradiation with 30 MeV α particles on natural tantalum target. The short-lived 182,182mRe were allowed to decay and long-lived nca 183Re was separated from bulk tantalum matrix by aqueous biphasic system (ABS) using 2 M solutions of nine different salts, namely, Na2SO4, Na2SO3, NaHSO3, Na2S2O3, Na2HPO4, Na2CO3, Na-citrate, Na-tartrate, and (NH4)2SO4 as salt rich phases against 50% (w/w) PEG-4000 as polymer rich phase at room temperature. The influence of temperature and thermodynamic parameters Δ Hº and Δ Sº were obtained for the partition of 183Re and tantalum in these systems. Nca 183Re was extracted in high amount in polymer rich phases irrespective of the salt rich phases. Bulk tantalum showed tendency to remain in salt rich phases. ABSs with PEG-4000 polymer rich phase in combination with Na2SO4, Na2SO3, NaHSO3, Na2HPO4, Na2CO3, Na-citrate and Na-tartrate as salt rich phases at basic pH and at ambient temperature (27 ºC) offered single-step separation between nca 183Re and bulk Ta. When Na2S2O3 and (NH4)2SO4 were used as salt rich phase, slight extraction of bulk tantalum was observed in PEG-4000 rich phase. The dynamic dissociation constant of 183Re-PEG-4000 complex was measured by dialysis of the PEG-rich phase against de-ionised water. The k dissociation value was found as low as 0.0185 min−1. Therefore, it is possible to have pure 183Re in de-ionized water immediately after the dialysis.

Activation cross sections for reactions induced by 14 MeV neutrons on natural tantalum

Cross sections for $(n,2n)$, $(n,p)$, $(n,{n}^{'}\ensuremath{\alpha})$, $(n,t)$, $(n,{d}^{'})$, and $(n,\ensuremath{\alpha})$ reactions have been measured on tantalum isotopes at the neutron energies of 13.5 to 14.7 MeV using the activation technique. Data are reported for the following reactions: $^{181}\mathrm{Ta}(n,2n)^{180}\mathrm{Ta}{}^{g}$, $^{181}\mathrm{Ta}(n,p)^{181}\mathrm{Hf}$, $^{181}\mathrm{Ta}(n,{n}^{'}\ensuremath{\alpha})^{177}\mathrm{Lu}{}^{m}$, $^{181}\mathrm{Ta}(n,t)^{179}\mathrm{Hf}{}^{m2}$, $^{181}\mathrm{Ta}(n,{d}^{'})^{180}\mathrm{Hf}{}^{m}$, and $^{181}\mathrm{Ta}(n,\ensuremath{\alpha})^{178}\mathrm{Lu}{}^{m}$. The neutron fluences were determined using the monitor reaction $^{27}\mathrm{Al}(n,\ensuremath{\alpha})^{24}\mathrm{Na}$. Results were discussed and compared with the previous works.

Neutron total cross-sections and resonance parameters of Mo and Ta

Experimental results of transmissions for the samples of natural molybdenum with thickness 0.0192 atoms/barn and for the four samples of natural tantalum with thickness 0.0222, 0.0111, 0.0055 and 0.0025 atoms/barn are presented in this work. Measurements were carried out at the Pohang Neutron Facility which consists of a 100 MeV Linac, water-cooled tantalum target, and 12 m flight path length. Effective total cross-sections were extracted from the transmission data, and resonance parameters were obtained by using the code SAMMY. The present measurements were compared with other measurements and with the evaluated nuclear data file ENDF/B-VI.8.

Depopulation of the Jπ = 9- isomer in 180Ta to the Jπ = 1+ ground state by Coulomb excitation

In-beam Coulomb excitation of the exotic odd-odd nucleus 180Ta has been studied by using a 136Xe beam and a setup consisting of five EUROBALL CLUSTER detectors and the Darmstadt-Heidelberg Crystal Ball array. Spectroscopic information on the extremely rare 180Ta is obtained from the comparison between an enriched (3.6±0.3% 180Ta) and a natural tantalum target. Possible evidence for a depopulation from the long-lived high-spin Jπ = 9- isomer to the short-lived Jπ = 1+ ground state is searched for by different methods. The decay of low-K bandheads, which are nanosecond isomers, towards the ground-state band can be demonstrated in delayed spectroscopy. A γγ coincidence analysis provides indications of K = 5 in-band transitions. Finally, when the Crystal Ball is used as an energy and γ multiplicity filter, signals of decay into the K = 0 band are observed.

Recovery of hafnium radioisotopes from a proton irradiated tantalum target

The178m2Hf nucleus, with its long half-life (31 y) and high-spin isomeric state (16+) is desired for new and exotic nuclear physics studies. The Los Alamos Radioisotope Program irradiated a kilogram of natural tantalum at the Los Alamos Meson Physics Facility in early 1981. After fifteen years of decay, this target was ideal for the recovery of178m2Hf. There was more than a millicurie of178m2Hf produced during this irradiation and there has been a sufficient period of time for most of the other hafnium radioisotopes to decayed away. Traditionally, separation techniques for recovering hafnium isotopes from tantalum targets employ solvent extractions with reagents that are considered hazardous. These techniques are no longer condoned because they generate a mixed-waste (radioactive and hazardous components) that can not be treated for disposal. In this paper we describe a new and unique procedure for the recovery of hafnium radioisotopes from a highly radioactive, proton irradiated, tantalum target using reagents that do not contribute a hazardous waste component.

Coulomb excitation of180Ta

The existence of a low energetic intermediate state (IS) in ${}^{180}\mathrm{Ta}$ which provides a coupling of the stable isomer and the radioactive ground state was investigated by means of Coulomb excitation. Natural tantalum foils were irradiated by protons with incident energies between 3.0 and 3.7 MeV, and with $\ensuremath{\alpha}$ particles in the energy range $12\ensuremath{-}20 \mathrm{MeV}.$ Subsequently, the foils were counted for the induced ground state activity of ${}^{180}\mathrm{Ta}.$ From the thick target yields an IS between 0.6 and 2.2 MeV excitation energy was inferred. The population of the IS in the stellar environment of the $s$ process depends critically on the prevailing temperatures. Current stellar models suggest $s$-process temperatures below $3.1\ifmmode\times\else\texttimes\fi{}{10}^{8} \mathrm{K}$ which lead to a negligible population of intermediate states above 1.2 MeV. Thus, the present data do not allow stringent conclusions about the destruction of ${}^{180}\mathrm{Ta}$ under these conditions, but an $s$ process origin seems still possible. Furthermore, the experiments support the existence of a new isomer in ${}^{184}\mathrm{Re}.$

Depopulation of 180Tam by Coulomb excitation and possible astrophysical consequences.

The depopulation of [sup 180]Ta[sup [ital m]] by Coulomb excitation was investigated in a thick-target experiment using beams of [sup 32]S and [sup 36]S with energies of 70--130 MeV on disks of natural tantalum. The resulting [sup 180]Ta ground-state population was measured by detecting its eight-hour decay. At the higher incident energies the observed [sup 180]Ta yield is dominated by sub-Coulomb neutron pickup transfer reactions on the 10[sup 4] times more abundant [sup 181]Ta. At the lower incident energies in [sup 180]Ta ground-state yield is found to be compatible with Coulomb excitation of the isomer to an intermediate level with energies [ital E][sub [ital x]][lt]1 MeV and a reduced transition probability [ital B]([ital E]2)[congruent]0.02--0.25 Weisskopf units. Consequences for the astrophysical production mechanism of [sup 180]Ta are discussed.

Resonance Parameters of Tantalum-181 in Neutron Energy Range from 100 to 4,300eV

Neutron transmission measurements were performed on natural tantalum (abundance ratio 99.988% for 181Ta) in the energy range of 100–4,300 eV using the Japan Atomic Energy Research Institute linac. The transmissions were measured using 55 and 190 m time-of-flight spectrometers for two and three samples of different thicknesses, respectively. These transmission data were simultaneously analyzed with a least squares fitting program based on a multl-level Breit-Wigner formula, and resonance energies and neutron width were obtained for 696 resonances of 181Ta. The statistical analysis of these parameters gave the s-wave average level spacing of D=4.10±0.14 eV and s-wave neutron strength functions of (1.67±0.13) × 10−4, (1.09 ± 0.09) × 10−4 and (1.42 ± 0.20) × 10−4 for the energy intervals from 100 − 1,700 eV, 1,700–3,400 eV and 3,400–4,300 eV, respectively. This significant difference among the neutron strength function for each energy interval is a prominent result of the present experiments and is of great i...

Resonance parameters of tantalum-181 in neutron energy range from 100 to 4,300eV.

Neutron transmission measurements were performed on natural tantalum (abundance ratio 99.988% for 181Ta) in the energy range of 100–4,300 eV using the Japan Atomic Energy Research Institute linac. The transmissions were measured using 55 and 190 m time-of-flight spectrometers for two and three samples of different thicknesses, respectively. These transmission data were simultaneously analyzed with a least squares fitting program based on a multl-level Breit-Wigner formula, and resonance energies and neutron width were obtained for 696 resonances of 181Ta. The statistical analysis of these parameters gave the s-wave average level spacing of D=4.10±0.14 eV and s-wave neutron strength functions of (1.67±0.13) × 10−4, (1.09 ± 0.09) × 10−4 and (1.42 ± 0.20) × 10−4 for the energy intervals from 100 − 1,700 eV, 1,700–3,400 eV and 3,400–4,300 eV, respectively. This significant difference among the neutron strength function for each energy interval is a prominent result of the present experiments and is of great interest.

Two-quasiparticle excited neutron levels inTa180

Excited neutron rotational levels have been observed in $^{180}\mathrm{Ta}$ up to an excitation energy of 1 MeV using the $^{181}\mathrm{Ta}$(d,t)$^{180}\mathrm{Ta}$ reaction. New assignments have been proposed for levels in the ${\frac{7}{2}}^{+}{[404]}_{\ensuremath{\pi}}\ifmmode\pm\else\textpm\fi{}{\frac{1}{2}}^{\ensuremath{-}}{[521]}_{\ensuremath{\nu}}$ and ${\frac{7}{2}}^{+}[404]\ifmmode\pm\else\textpm\fi{}{\frac{7}{2}}^{\ensuremath{-}}[514]$ configurations. Levels in the latter are discussed with regard to configuration mixing between low energy ${K}^{\ensuremath{\pi}}={8}^{+}$ bands expected in $^{180}\mathrm{Ta}$.NUCLEAR REACTIONS $^{181}\mathrm{Ta}$(d,t)$^{180}\mathrm{Ta}$ with natural tantalum oxide target; ${E}_{\mathrm{d}}=17.4$ MeV; measured ${E}_{\mathrm{t}}$ and $\ensuremath{\sigma}(\ensuremath{\theta})$ with QDDD spectrometer; DWBA analysis; deduced levels ${I}^{\ensuremath{\pi}}$, $K$.NUCLEAR STRUCTURE $^{180}\mathrm{Ta}$ assigned Nilsson configurations; failure to observe configuration mixing between expected low energy ${K}^{\ensuremath{\pi}}={8}^{+}$ bands.

Production and purification of tungsten-178

The feasibility of making large activity levels of 178W using the high-current proton beam available at the Brookhaven Linac Isotope Producer (BLIP) facility has been investigated. The radionuclide was produced by the ( p, 4 n) reaction on 181Ta. A 0.127 mm thick natural tantalum foil was irradiated at various incident proton energies in the range 47–97 MeV. The target was dissolved in a mixture of hydrofluoric and nitric acids, and the tungsten separated from the tantalum using an ion-exchange procedure. A Ge(Li) gamma-ray spectrum of the purified 178W demonstrated detectable activity only from the 178W and its daughter radionuclide 178Ta. With this procedure 100 mCi quantities of the parent nuclide could, for example, be produced by bombardments for 3 days with 47 MeV protons using beam currents averaging approximately 70 μA.