Tellurium Isotopes Research Articles

Chalcogen isotopes reveal limited volatile contribution from late veneer to Earth.

The origin of Earth's volatile elements is highly debated. Comparing the chalcogen isotope ratios in the bulk silicate Earth (BSE) to those of its possible building blocks, chondritic meteorites, allows constraints on the origin of Earth's volatiles; however, these comparisons are complicated by potential isotopic fractionation during protoplanetary differentiation, which largely remains poorly understood. Using first-principles calculations, we find that core-mantle differentiation does not notably fractionate selenium and tellurium isotopes, while equilibrium evaporation from early planetesimals would enrich selenium and tellurium in heavy isotopes in the BSE. The sulfur, selenium, and tellurium isotopic signatures of the BSE reveal that protoplanetary differentiation plays a key role in establishing most of Earth's volatile elements, and a late veneer does not substantially contribute to the BSE's volatile inventory.

Structure of the Charge-Exchange Strength Function of Tellurium Isotopes 128 and 130

Structure of the Charge-Exchange Strength Function of Tellurium Isotopes 128 and 130

Experimental study of alpha-induced nuclear reactions on Tellurium isotopes for the astrophysical γ-process

Heavier p isotopes are believed to be produced through the γ-process. The path of γ-process can be modelled with network calculations. These calculations include about 20000 reactions on more than 2000, mostly unstable nuclei, many of these reactions involves alpha particles. Theoretical cross sections of reactions involving alpha particles are found to be very sensitive to the alpha-nucleus optical potential, which is not known well enough at low, astrophysical energies. This potential can be studied experimentally by measuring the cross section of (α,n) reactions close above the reaction threshold. The aim of the present work is thus to measure the cross section of the 122Te(α,n)125Xe, 124Te(α,n)127Xe and 130Te(α,n)133Xe reactions for which no data exist in literature. The half-life of the produced Xe isotopes allows us to use the activation technique. Tellurium targets with natural isotopic composition will be used in order to measure the three reactions in parallel. The experiments are in progress using the cyclotron accelerator of ATOMKI. In this paper details of the experimental technique and the preliminary results of the first test measurements are presented.

Tellurium isotope fractionation during evaporation from silicate melts

As a moderately volatile, redox-sensitive chalcophile and siderophile element, Te and its isotopic composition can inform on a multitude of geochemical and cosmochemical processes. However, the interpretation of Te data from natural settings is often hindered by an insufficient understanding of the behavior of Te in high-temperature conditions. Here, we present the results of Te evaporation and isotopic fractionation in silicate melting experiments. The starting material was boron-bearing anorthite-diopside glass with 1 wt% TeO2. The experiments were conducted over the temperature range of 868–1459 °C for 15 min each, and at oxygen fugacities (logfO2) relative to the fayalite-magnetite-quartz buffer (FMQ) of FMQ−6 to FMQ+1.5, and in air. Evaporation of Te decreases with decreasing fO2. For high-temperature experiments performed at >1200 °C Te loss is accompanied by Te isotope fractionation towards heavier compositions in the residual glasses. By contrast, Te loss in experiments performed at temperatures <1200 °C typically resulted in lighter Te isotopic compositions in the residues relative to the starting material. In air, Te evaporates as TeO2, whereas at lower oxygen fugacities we predict the evaporation of Te2, using Gibbs free energy minimization calculations. In air, the experimentally determined kinetic isotopic fractionation factor for δ128/126Te at T > 1200 °C is αK = 0.99993. At reducing conditions, Te likely substitutes as Te2− for O2– in the melt structure and becomes increasingly soluble at highly reducing conditions. Consequently, Te evaporation is not predicted for volcanic processes on reduced planetary bodies such as the Moon or Mercury.

Study of the Cross-Section for the 122Te(γ, n)121Te Reaction by the Activation Method

Relevance. The study of photonuclear reactions plays a defining role in the formation of modern ideas about highlocalized collective excitations in nuclei of the giant resonance type. The giant dipole E1-resonance (GR) is the main feature in γ-quantum absorption cross-sections of nuclei. The presence of isotopes with multiple isotopes makes it possible to trace the evolution of GR characteristics from changes in the number of neutrons in the nuclei. One such element is tellurium. Purpose. The purpose of this research is an experimental and theoretical study of the cross-section of 122Te(γ, n)121Te reaction in the region of giant E1-resonance energies. Methods. The study of the cross-section of (γ, n) reaction on 122Te isotope was performed on the bremsstrahlung γ-beam of the M-30 microtron of the Institute of Electronic Physics of the National Academy of Sciences of Ukraine. The yield curves were measured in the range of maximum gamma-quantum energies Eγmax=10-18 MeV. The reaction cross-section was calculated by the inverse matrix method. When registering the reaction products, an activation technique was used, while the gamma activity of the products was recorded by the spectrometric method. The theoretical calculations of the cross-section for the 122Te(γ, n)121Te reaction were performed using the TALYS-1.9 software package. Results. The measured experimental yield ratios of the 122Te(γ, n)121Te і 130Te(γ, n)129Te d= Yn121 /Yn129 = f (E max) reactions allowed the experimental cross-section for the 122Te(γ, n)121Te reaction to be calculated. The cross-section has a single hump shape with a maximum at an energy of ~ 15.3 MeV. It was approximated by the Lorentz curve with the parameters δ0 =(274.1±2.1) MB, Е0 (15.27±0.10) MeV, Г0 =(4.76±0.08) MeV. The cross-section obtained was compared with similar cross-sections for 126Te and 130Te isotopes, as well as with theoretical calculations according to the TALYS-1.9 program. Conclusions. The obtained cross-section for the 122Te(γ, n)121Te reaction is consistent with the evolution of the parameters of (γ, n) reaction cross-section on tellurium isotopes 130Te(γ, n)129Te with a change in the number of neutrons. The theoretical approaches used are satisfactorily consistent with the experimental data. This agreement indicates the main contribution of the statistical mechanism to the cross-section of the considered (γ, n) reaction and a relatively small contribution of semi-direct processes

Expected sensitivity to 128Te neutrinoless double beta decay with the CUORE TeO2 cryogenic bolometers

The CUORE experiment is a ton-scale array of hbox {TeO}_2 cryogenic bolometers located at the underground Laboratori Nazionali del Gran Sasso of Istituto Nazionale di Fisica Nucleare (INFN), in Italy. The CUORE detector consists of 988 crystals operated as source and detector at a base temperature of sim 10 mK. Such cryogenic temperature is reached and maintained by means of a custom built cryogen-free dilution cryostat, designed with the aim of minimizing the vibrational noise and the environmental radioactivity. The primary goal of CUORE is the search for neutrinoless double beta decay of ^{130}hbox {Te}, but thanks to its large target mass and ultra-low background it is suitable for the study of other rare processes as well, such as the neutrinoless double beta decay of ^{128}hbox {Te}. This tellurium isotope is an attractive candidate for the search of this process, due to its high natural isotopic abundance of 31.75%. The transition energy at (866.7 ± 0.7) keV lies in a highly populated region of the energy spectrum, dominated by the contribution of the two-neutrino double beta decay of ^{130}hbox {Te}. As the first ton-scale infrastructure operating cryogenic hbox {TeO}_2 bolometers in stable conditions, CUORE is able to achieve a factor >10 higher sensitivity to the neutrinoless double beta decay of this isotope with respect to past direct experiments.

Microscopic description of even–even medium-mass tellurium isotopes within the projected shell model

The low-lying energy levels, B(E2) transition probabilities and g-factors of even–even medium-mass tellurium isotopes have been studied by employing the projected shell model (PSM) approach. The oblate ground state deformations are taken in this study that were predicted in previous relativistic Hartree Bogoliubov mean field study. The low-lying yrast and yrare states are reproduced well in these calculations. The energy and configuration of yre states are also predicted. The experimental B(E2) values and their systematics with neutron number are reproduced well in the medium-mass Te isotopes. The experimental data are available for [Formula: see text]-factors of 2[Formula: see text] states of [Formula: see text]Te isotopes which is in line with these calculations. The enhancement of g-factors at spin I = 6[Formula: see text] in all the Te isotopes considered may be attributable to the alignment of protons in [Formula: see text] subshell. Furthermore, the reduction of g-factors at spin [Formula: see text] in [Formula: see text]Te and [Formula: see text] in [Formula: see text]Te may be attributable to the alignment of neutrons in the [Formula: see text] subshell. The 8[Formula: see text] states of [Formula: see text]Te are envisaged to be of [Formula: see text] nature and in [Formula: see text]Te these states are found to be of [Formula: see text] nature.

Concentration of Tellurium Isotopes by a Multistage Scheme in an Ordinary Cascade of Gas Centrifuges

Concentration of Tellurium Isotopes by a Multistage Scheme in an Ordinary Cascade of Gas Centrifuges

Study on Vibrational-Gamma Soft Properties in 124Te Nucleus

The study of tellurium isotopes is very important for nuclear physicist during the last two decades. The tellurium isotope with 72 numbers of neutrons is very much interesting to study the nuclear collectivity based on experimental and theoretical aspects. Because it is an even-even nucleus and easily produced E2 transitions where the low-lying excitation levels

Optimization of flexible square cascade for high separation of stable isotopes using enhanced PSO algorithm

The optimal parameters of a flexible square cascade for the separation of multicomponent isotopes have been calculated in this paper. In this regard, a new code called “MCSQCA-PSO” has been developed, which uses the particle swarm algorithm with mutation operator to find the optimal solution. Maximizing the amount of product recovery in a square cascade with the certain number of centrifuges machines and considering the concentration of the desired isotope in specific values, as well as increasing the D function as an objective function have been evaluated and studied. Cascade feed flow rate, machine feed flow rate, cascade cut, feed entrance point, and stages cut have been defined as optimization variables in the code. Optimization calculations are performed as an example for separation of Te-123, which has the most challenging separation between the eight stable isotopes of tellurium. In this paper, all possible arrangements of a square cascade assuming 200 centrifuges for two different separation factors have been investigated, and the enrichment of Te-123 has been increased from 0.89 % in natural feed to 65 %. The results show that the recovery coefficient increases nonlinearly with increasing the number of stages from 10 to 100, so that it is not significantly different for cascades in 40, 50, and 100 stages. In contrast, the amount of product in the cascade with 50 stages is the highest in comparison with the other cascades. Finally, the recovery coefficients of Te-123 in the cascade with 50 stages for two different separation factors have obtained 99.46 % and 92.38 %, respectively. The amount of product after two steps of separation and assuming one year of operation have been obtained 4.6 kg and 4.1, respectively. Furthermore, the ability of MCSQCA-PSO is evaluated with other optimization algorithms. Suitable alignment of the results indicates that the use of the PSO for this problem guarantees the calculation of the optimal parameters.

Tellurium retention by containment spray system

A containment spray system is used to mitigate the source term from the containment building to the environment as part of the severe accident management actions. Tellurium is one of the volatile fission products and many of the tellurium isotopes decay into iodine, which causes a threat to the public due to its radiotoxicity and build-up in the thyroid gland. The removal efficiency of the containment spray system model against tellurium species formed under severe accident conditions was investigated with experiments and MELCOR simulations. The results indicated efficient removal of tellurium aerosols in the air atmosphere, whereas a decrease in the efficiency was observed in the nitrogen atmosphere. Gaseous tellurium species were not formed in significant amounts during the experiments and therefore, the removal efficiency due to different spray chemistry conditions could not be accurately analysed. However, the alkaline chemicals used in the spray solution seemed to form airborne particles, increasing the overall aerosol transport in the process independently of CsI or Te aerosol transport.

Symmetric and asymmetric structural evolutions of Te isotopes across the N = 82 shell closure * *Supported by National Natural Science Foundation of China (11875188, 11905130 and 12075169), Sichuan Science and Technology Program (2019JDRC0017), the Doctoral Program of Southwest University of Science and Technology (18zx7147), and Shanghai Sailing Program (19YF1434200)

Systematic calculations of low-lying energy levels, transitions, and g factors of even-even tellurium isotopes with mass numbers from 128 to 140 are performed via the nucleon-pair approximation (NPA) of the shell model with phenomenological multipole-multipole interactions. An optimal agreement is obtained between the calculated results and experimental data. The yrast band structures of nuclei below and above the shell closure are compared and discussed. In particular, the evolutionary differences of values and factors, with respect to the symmetry of , are attributed to the dominant contribution differences in neutron and proton excitations, respectively.

Tellurium isotope cosmochemistry: Implications for volatile fractionation in chondrite parent bodies and origin of the late veneer

Tellurium stable isotope compositions and abundances (δ128/126Te relative to SRM 3156) are reported for 43 ordinary, enstatite, and Rumuruti chondrites, which together with results from a companion study on carbonaceous chondrites are used to assess the origin of volatile element fractionations in chondrites. Whereas Te isotope variations among carbonaceous chondrites predominantly reflect mixing between isotopically light chondrules/chondrule precursors and CI-like matrix, Te isotope variations among non-carbonaceous chondrites mainly result from Te redistribution during parent body thermal metamorphism. The enstatite chondrites in particular display increasingly heavy Te isotopic compositions and decreasing Te concentrations with increasing degree of metamorphism, indicating migration of isotopically light Te from the strongly metamorphosed inner parts towards the cooler outer regions of the parent bodies. By contrast, ordinary and Rumuruti chondrites display less systematic Te isotope variations, implying more localized redistribution of Te during parent body thermal metamorphism.We also report Te stable isotope data for 19 terrestrial mantle-derived rocks. Peridotites with Al2O3 contents close to those inferred for the bulk silicate Earth (BSE) exhibit uniform δ128/126Te values, which we interpret to represent the Te isotopic composition of the BSE. This composition overlaps with the Te isotope composition of some volatile-rich carbonaceous chondrites (most notably CM chondrites), but also with that of enstatite chondrites. Comparison of the Te results to Se isotopes and Se/Te ratios shows that due to uncertainties in the composition of the BSE and the isotopic composition of bulk chondrite parent bodies, neither Te isotopes alone nor the combined Se-Te elemental and isotopic systematics can distinguish between a carbonaceous and enstatite chondrite-like late veneer, which is the presumed source of Se and Te in the BSE. Together, the results of this study illustrate that the relative abundances and mass-dependent isotope compositions of volatile elements like Se and Te are modified by physical and chemical processes occurring after planetary accretion, which severely complicates their use as genetic tracers. A corollary of this is that contrary to prior proposals the Se-Te systematics are not contradicting an inner solar system origin of the late veneer, as it has been inferred using nucleosynthetic isotope anomalies of other elements.

Analysis and Filtration of Nanoparticles during Heating of Spherical Simulators of Fuel Elements in Helium

A technique is described and analysis of radioactive nanoaerosols formed during heating of spherical simulators of fuel elements for high-temperature gas-cooled reactors in helium to 1500 K has been carried out. It was found that upon high-temperature gas corrosion and leakage of radioactive fission products from fuel elements, nanoaerosols of graphite with iodine and tellurium isotopes can be formed. More than 80% of their γ-activity is accounted for by particles ranging in size from 0.002 to 0.5 μm. Their filtration by highly efficient fiberglass and membrane cermet filters with multilayer and regenerable nanostructure at increased temperatures has been studied.

Status and Perspectives on Rare Decay Searches in Tellurium Isotopes

Neutrinoless double beta decay (0νββ) is a posited lepton number violating decay whose search is an increasingly active field in modern astroparticle physics. A discovery would imply neutrinos are Majorana particles and inform neutrino physics, cosmology and beyond-standard-model theories. Among the few nuclei where double beta decay (ββ) is allowed, tellurium isotopes stand for their high natural abundance and are currently employed in multiple experiments. The search for 0νββ will provide large exposure data sets in the coming years, paving the way for unprecedented sensitivities. We review the latest rare decay searches in tellurium isotopes and compare past results with theories and prospects from running experiments.

Analysis of low-lying states, neutron-core excitations, and electromagnetic transitions in tellurium isotopes Te130–134

The neutron-rich $^{130--134}\mathrm{Te}$ isotopes are investigated by large-scale shell-model calculations with the extended pairing plus multipole-multipole force (EPQQM model). The orbits of $(0{g}_{7/2},1{d}_{5/2},1{d}_{3/2},2{s}_{1/2},0{h}_{11/2})$ are included for both proton and neutron model space, while two more neutron orbits $(1{f}_{7/2},2{p}_{3/2})$ above the $N=82$ shell gap are included to study neutron-core excitations. The higher core-excited states in $^{132,133}\mathrm{Te}$ are calculated for the first time in this region. The present work well describes both the low-lying and the high-energy states for $^{134}\mathrm{Te}$, $^{133}\mathrm{Te}$, and $^{132}\mathrm{Te}$, as well as the low-lying levels of $^{131}\mathrm{Te}$ and $^{130}\mathrm{Te}$. The several multiplets with clear boundary exist in $^{134,133}\mathrm{Te}$, while a new configuration lying between 4.8 and 6.0 MeV is found as a theoretical prediction in $^{134}\mathrm{Te}$. Finally, the transition probabilities in these nuclei are calculated and compared with available data. The predicted energy levels and electromagnetic transition will be useful for planning future experiments.

Tellurium Behavior in the Containment Sump: Dissolution, Redox, and Radiolysis Effects

In the event of a severe nuclear accident, one major concern is the release of radioactive material into the environment causing potential exposure of the general public to radiation. Among the volatile radionuclides are a range of tellurium isotopes. Due to the radioactivity and the volatility of tellurium, it has to be taken into account when assessing the overall effects of an accident. The interest in tellurium is not limited only to its release but also to the fact that some tellurium isotopes decay to iodine, and thus affect the iodine release behavior. The release and transport behavior of tellurium has been investigated over the past decades, however, the aqueous chemistry of tellurium in the complex containment sump system is still unclear. This study presents the behavior of tellurium dioxide in simplified containment sump conditions in relation to dissolution, redox reactions, and interactions with water radiolysis products. The results indicate that radiolysis products have a significant effect on tellurium chemistry in both a reducing and oxidizing manner depending on the solution composition. The redox reactions also affect the solubility of tellurium. The results show that the current information used to assess tellurium source term needs to be reevaluated for both severe accident management and for code validation purposes.

Study of light tellurium isotopes along the yrast line

The projected shell model is employed to study the light tellurium isotopes along the yrast line. The results are obtained for yrast bands, moment of inertia and B(E2) transition probabilities. Besides this, the systematics of E21+,E41+/E21+ and B(E2;21+⟶01+) and BCS subshell occupation numbers are investigated in light 106−112Te isotopes. The results on moment of inertia predict the occurrence of phenomenon of backbending around the band crosssing region due to the alignment of a pair of neutrons in the neutron 1h11/2 subshell. The maximum collectivity is observed at N = 60 due to the large neutron-proton (n-p) interaction between spin-orbit partner (SOP) [(g9/2)π, (g7/2)ν] orbits and occupation of down slopping components of νh11/2 subshell.

Precise Measurement of Tellurium Isotope Ratios in Terrestrial Standards Using a Multiple Collector Inductively Coupled Plasma Mass Spectrometry.

Precise tellurium (Te) isotope ratio measurement using mass spectrometry is a challenging task for many decades. In this paper, Te isotope ratio measurements using multi-collector inductively coupled plasma mass spectrometry (MC–ICP–MS) in terrestrial Te standards have been reported. Newly developed Faraday cup with 1012 Ω resistor is used to measure low abundance 120Te, whereas the 1011 Ω resistor is used to measure other Te isotopes. The relative standard deviation obtained for Te isotope ratio measurement by Faraday cups of 120Te/128Te [0.002907(05)], 122Te/128Te [0.079646(10)], 123Te/128Te [0.027850(07)], 125Te/128Te [0.221988(09)], 126Te/128Te [0.592202(20)], and 130Te/128Te [1.076277(30)] were 0.140%, 0.014%, 0.026%, 0.005%, 0.004%, and 0.004%, respectively. The measured isotope ratio results are compared with previous results obtained by thermal ionization mass spectrometry (TIMS), negative thermal ionization mass spectrometry (N–TIMS), and MC–ICP–MS, showing an improvement in the precision about one order of magnitude for 120Te/128Te ratio. The present study shows better precision for Te isotope ratios compared to earlier studies.

Rotational Behavior of Triaxially Deformed Even–Even Tellurium Isotopes

Rotational Behavior of Triaxially Deformed Even–Even Tellurium Isotopes