Luminescent decay of ki- tl, kbr- tl, and kcl- tl.
Emission spectra and luminescent decay of thallium excited potassium iodide investigated over temperature range of 10 to 300 degrees k
POTASSIUM IODIDE↗
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Results for “Tl”
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Exploring Spin‐Orbit Effects in a [Cu 6 Tl] + Nanocluster Featuring an Uncommon Tl−H Interaction
Reaction of [CuH(PPh 3 )] 6 with 1 equiv. of Tl(OTf) results in formation of [Cu 6 TlH 6 (PPh 3 ) 6 ][OTf] ([1]OTf]), which can be isolated in good yields. Variable-temperature 1 H NMR spectroscopy, in combination with density functional theory (DFT) calculations, confirms the presence of a rare Tl−H orbital interaction. According to DFT, the 1 H chemical shift of the Tl-adjacent hydride ligands of [1] + includes 7.7 ppm of deshielding due to spin-orbit effects from the heavy Tl atom. In conclusion, this study provides valuable new insights into a rare class of metal hydrides, given that [1][OTf] is only the third isolable species reported to contain a Tl−H interaction.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
First Exploration of Monopole-Driven Shell Evolution above the N = 126 Shell Closure: New Millisecond Isomers in Tl 213 and Tl 215
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190 ≤ A ≤ 219↗
Materials Data on Tl by Materials Project
Tl is alpha La structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent Tl sites. In the first Tl site, Tl is bonded to twelve Tl atoms to form a mixture of edge, face, and corner-sharing TlTl12 cuboctahedra. There are six shorter (3.52 Å) and six longer (3.55 Å) Tl–Tl bond lengths. In the second Tl site, Tl is bonded to twelve Tl atoms to form a mixture of edge, face, and corner-sharing TlTl12 cuboctahedra. All Tl–Tl bond lengths are 3.55 Å.
36 MATERIALS SCIENCE↗
Behavior of the Mo, Tl, and U isotope systems during differentiation in the Kilauea Iki lava lake
Stable molybdenum (Mo), thallium (Tl), and uranium (U) isotope ratios were determined in a suite of samples from the 1959 Kilauea eruption and from Kilauea Iki lava lake with the aim of understanding the effects of igneous differentiation on these isotope systems. The samples range from olivine cumulate with MgO up to 27% to internal differentiates with MgO less than 3%, representing a tholeiitic differentiation series. Molybdenum, Tl, and U behave incompatibly during differentiation, and Mo and U isotope ratios do not systematically vary amongst the different samples. δ 98 Mo values range from -0.17 to -0.31‰ and δ 238 U values range from -0.20 to -0.38‰. Most individual analyses for both isotope systems overlap within measurement uncertainty (± ~0.7 and ~ 0.6, respectively). Mean δ 98 Mo and δ238U values are -0.22 ± 0.08‰ (2σ) and - 0.29 ± 0.09‰ (2σ), respectively, which overlap with Pacific mid ocean ridge basalt (MORB). In contrast, Tl isotopes show small but resolvable variations, with ε 205 Tl ranging from +1.20 to -1.38. The most negative ε 205 Tl values are confined to some of the lowest [Tl] samples, but the ε 205 Tl values do not otherwise vary smoothly with MgO or [Tl]. Possible mechanisms for thallium isotope fractionation are considered (e.g., degassing, water leaching, sulfide fractionation) but none are found to be satisfactory. Overall, the lack of resolvable variation in the Mo and U isotope systems and the small magnitude of heterogeneity in the Tl isotope system indicate that differentiation in tholeiitic systems is unlikely to be a major contributor to global variation in these isotope systems.
58 GEOSCIENCES↗
Investigation of the competition between Tl + and Ce 3+ scintillation in Tl2LiYCl6:Ce, an elpasolite scintillator
Li-containing elpasolite scintillators are currently investigated for their ability to detect both thermal neutrons and gamma photons with a single inorganic crystal. The scintillation is typically triggered by using an activator such as Ce. However, when Tl, also a luminescent ion, is present in the matrix, competition between the two centers Tl and Ce can occur. In this study, we are using Ce doped Tl 2 LiYCl 6 to investigate this competition. To this end, the Ce (which substitutes Y) concentration is varied from 0 to 1 in the Tl 2 LiY 1-x CexCl 6 composition. In the low concentration range in which Ce remains a dopant, the photo- and radioluminescence spectra show that the scintillation of Tl 2 LiYCl 6 :Ce is mostly dominated by recombination on intrinsic luminescent centers. For cerium concentrations higher than x = 0.02, very different emissions can be easily distinguished from the photo- and radioluminescence of undoped and low Ce doped Tl 2 LiYCl 6 crystals. These emissions are attributed to the formation of a second phase Tl 2 CeCl 5 , identified by X-ray diffraction. We conclude that the intrinsic luminescence related to Tl dominates the scintillation in the range of concentration for which Ce does substitute on the Y-site.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Time-lens photon Doppler velocimetry (TL-PDV)
Here, we describe a time lens (TL) to expand the dynamic range of photon Doppler velocimetry (PDV) systems. The principle and preliminary design of a TL-PDV system are explained and shown to be feasible through simulations. In a PDV system, an interferometer is used for measuring frequency shifts due to the Doppler effect from the target motion. However, the sampling rate of the electronics could limit the velocity range of a PDV system. A four-wave-mixing (FWM) TL applies a quadratic temporal phase to an optical signal within a nonlinear FWM medium (such as an integrated photonic waveguide or a highly nonlinear optical fiber). By spectrally isolating the mixing product, termed the idler, and with appropriate lengths of dispersion prior to and after this FWM TL, a temporally magnified version of the input signal is generated. Therefore, the frequency shifts of PDV can be “slowed down” with the magnification factor M of the TL. M = 1 corresponds to a regular PDV system without a TL. M = 10 has been shown to be feasible for a TL-PDV system. The use of this effect for PDV can expand the velocity measurement range and allow for the use of lower bandwidth electronics. TL-PDV will open up new avenues for various dynamic material experiments.
47 OTHER INSTRUMENTATION↗
Establishing Pb-203 production from electrodeposited Tl targets at Brookhaven National Laboratory
Background: Promising developments in Pb-212 radiopharmaceutical therapies have increased demand for Pb-203 diagnostic agents. Building on previous work from various isotope production facilities, this study optimized Pb-203 production from electrodeposited Tl targets at Brookhaven National Laboratory (BNL). The additional supply of Pb-203 may help meet growing preclinical and clinical demands. Results: Two Tl targets were irradiated at the Brookhaven Linac Isotope Producer facility with 30 ± 1 MeV protons, measured using previously published cross section data. Distribution coefficients for Pb Resin in acetate media were investigated for both Na + and K + cations, where potassium acetate was ~ 4 times more effective at stripping Pb from the Pb Resin. The Tl electrodeposition was optimized to deposit 350 mg of Tl (~ 60 mg/cm 2 ) on Au backing in under 6 h. The proposed separation process was completed in < 1.5 h and achieved > 98% and 92 ± 3% recovery of Tl and Pb, respectively, with an overall Tl-Pb separation factor of 6 × 10 5 . The experimentally measured half-life of Pb-203 was 52.4 ± 0.7 h, agreeing with 51.93 ± 0.02 h reported by the National Nuclear Data Center. The radioisotopic purity of the Pb fraction at 24 h post end of bombardment (EOB) from a 24 h irradiation was 66% Pb-203, 28% Pb-201, and 6% Pb-200. Following chemical separation, the Pb-203 produced in this work (21 MBq Pb-203 EOB) achieved apparent molar activities of 10 ± 5 and 0.9 ± 0.5 GBq/µmol for [ 203 Pb]Pb-DOTAM and [ 203 Pb]Pb-DO3A, respectively, decay corrected to EOB. Data derived from this work suggests BNL can produce > 10’s GBq Pb-203 with > 99% radiochemical and radioisotopic purity from Tl-205 for worldwide distribution. Conclusions: The production and separation of Pb-203 from natural Tl target material was successfully demonstrated at BNL. Existing methods were adapted and optimized for the facilities at BNL. Results from this work will guide future large-scale Pb-203 production opportunities at BNL for clinical applications.
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
Tl2Ir2O7: A Pauli Paramagnetic Metal, Proximal to a Metal Insulator Transition
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99 GENERAL AND MISCELLANEOUS↗
CsI(Tl) pulse shape discrimination with the Belle II electromagnetic calorimeter as a novel method to improve particle identification at electron–positron colliders
Here we describe the implementation and performance of CsI(Tl) pulse shape discrimination for the Belle II electromagnetic calorimeter, representing the first application of CsI(Tl) pulse shape discrimination for particle identification at an electron–positron collider. The pulse shape characterization algorithms applied by the Belle II calorimeter are described. Control samples of $γ, μ^+, π^±, K^±$ and $ρ/ \bar{ρ}$ are used to demonstrate the significant insight into the secondary particle composition of calorimeter clusters that is provided by CsI(Tl) pulse shape discrimination. Comparisons with simulation are presented and provide further validation for newly developed CsI(Tl) scintillation response simulation techniques, which when incorporated with GEANT4 simulations allow the particle dependent scintillation response of CsI(Tl) to be modelled. Comparisons between data and simulation also demonstrate that pulse shape discrimination can be a new tool to identify sources of improvement in the simulation of hadronic interactions in materials. The $K^0_L$ efficiency and photon-as-hadron fake-rate of a multivariate classifier that is trained to use pulse shape discrimination is presented and comparisons are made to a shower-shape based approach. CsI(Tl) pulse shape discrimination is shown to reduce the photon-as-hadron fake-rate by over a factor of 3 at photon energies of 0.2 GeV and over a factor 10 at photon energies of 1 GeV.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Magnetism and superconductivity of some Tl-Cu oxides
Many copper oxide based Thallium compounds are now known. In comparison to the Bi-compounds, the Tl-system shows a richer diversity; i.e., High Temperature Superconductors (HTSC) can be obtained with either one or two Tl-0 layers (m = 1,2); also, the triple-digit phases are easier to synthesize. The value of d, oxygen stoichiometry, is critical to achieving superconductivity. The Tl system is robust to oxygen loss; Tl may be lost or incorporated by diffusion. A diffusion coefficient equal to 10 ms at 900 C was determined. Both ortho-rhombic and tetragonal structures are found, but HTSC behavior is indifferent to the crystal symmetry. This system has the highest T(sub c) confirmed. T(sub c) generally increases with p, the number of CuO layers, but tends to saturate at p = 3. Zero resistance was observed at temperatures as great as 125 K. Most of these HTSC's are hole type, but the Ce-doped specimens may be electronic. The magnetic aspects were studied; because in addition to defining the perfectly diamagnetic ground state as in conventional superconductors, magnetism of the copper oxides show a surprising variety. This is true of both the normal and the superconducting states. Also, due to the large phonon contribution to the specific heat at the high T(sub c) jump, electronic density of states, D(Ef), and coherence length are uncertain, and thus, are estimated from the magnetic results. Results from the Tl-system CuO, LaBaCuO,120 and the Bi-CuO compounds are discussed. The emphasis is on the role of magnetism in the Tl-CuO HTSC, but technological aspects are also pointed out.
Datta, Timir↗
Materials Data on Tl(FeTe)3 by Materials Project
TlFe3Te3 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. there are three inequivalent Fe sites. In the first Fe site, Fe is bonded in a 10-coordinate geometry to six Fe and four Te atoms. There are two shorter (2.50 Å) and four longer (2.58 Å) Fe–Fe bond lengths. There are a spread of Fe–Te bond distances ranging from 2.66–2.68 Å. In the second Fe site, Fe is bonded in a 10-coordinate geometry to six Fe and four Te atoms. There are one shorter (2.50 Å) and two longer (2.58 Å) Fe–Fe bond lengths. There are a spread of Fe–Te bond distances ranging from 2.66–2.68 Å. In the third Fe site, Fe is bonded in a 10-coordinate geometry to six Fe and four Te atoms. There are a spread of Fe–Te bond distances ranging from 2.66–2.68 Å. Tl is bonded in a distorted trigonal planar geometry to nine Te atoms. There are a spread of Tl–Te bond distances ranging from 3.46–3.61 Å. There are three inequivalent Te sites. In the first Te site, Te is bonded in a 5-coordinate geometry to four Fe and three equivalent Tl atoms. In the second Te site, Te is bonded in a 7-coordinate geometry to four Fe and three equivalent Tl atoms. In the third Te site, Te is bonded in a 7-coordinate geometry to four Fe and three equivalent Tl atoms.
36 MATERIALS SCIENCE↗
Materials Data on Tl by Materials Project
Tl is Copper structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Tl is bonded to twelve equivalent Tl atoms to form a mixture of corner, edge, and face-sharing TlTl12 cuboctahedra. There are four shorter (3.47 Å) and eight longer (3.56 Å) Tl–Tl bond lengths.
36 MATERIALS SCIENCE↗
Materials Data on Tl by Materials Project
Tl is Tungsten structured and crystallizes in the cubic Im-3m space group. The structure is three-dimensional. Tl is bonded in a body-centered cubic geometry to eight equivalent Tl atoms. All Tl–Tl bond lengths are 3.43 Å.
36 MATERIALS SCIENCE↗
Materials Data on Tl by Materials Project
Tl is Magnesium structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Tl is bonded to twelve equivalent Tl atoms to form a mixture of face, edge, and corner-sharing TlTl12 cuboctahedra. There are six shorter (3.53 Å) and six longer (3.55 Å) Tl–Tl bond lengths.
36 MATERIALS SCIENCE↗
Crystal growth, scintillation properties & fast neutron-gamma discrimination of cubic halide perovskite CsCaCl 3 :(Eu 2+ , Tl + )
The vast variety of nuclear security applications require radiation detection materials tailored to their operational needs. A scintillator’s properties are strongly influenced by the choice of luminescent dopant, which facilitates customization to different applications. In this work, transparent Ø12 mm single crystals of undoped CsCaCl 3 , CsCaCl 3 :1% Eu, CsCaCl 3 :1% Tl, and CsCaCl 3 :1% Eu, 1% Tl were grown via the Vertical Bridgman method. Their scintillation properties and fast neutron-gamma discrimination capabilities were investigated. Undoped CsCaCl 3 had a light yield of 2,500 ph/MeV, which is the highest reported to date for this CVL material. The incorporation of Eu 2+ or Tl + into CsCaCl 3 as luminescence centers resulted in significantly higher light yields of ∼16,000 ph/MeV and energy resolutions of ∼8% at 662 keV. Compared to the single dopant counterparts, CsCaCl 3 :Eu, Tl had significantly suppressed afterglow; however, this came at the cost of reduced light yield. Among the materials tested, only CsCaCl 3 :Tl showed effective fast neutron and gamma discrimination capabilities, achieving a Figure of Merit of 3.2 between gamma-rays and fast neutron captures that produce protons and 1.6 between gamma-rays and fast neutron captures that produce alpha particles.
crystal growth↗
Physics-informed neural network with transfer learning (TL-PINN) based on domain similarity measure for prediction of nuclear reactor transients
Nuclear reactor safety and efficiency can be enhanced through the development of accurate and fast methods for prediction of reactor transient (RT) states. Physics informed neural networks (PINNs) leverage deep learning methods to provide an alternative approach to RT modeling. Applications of PINNs in monitoring of RTs for operator support requires near real-time model performance. However, as with all machine learning models, development of a PINN involves time-consuming model training. Here, we show that a transfer learning (TL-PINN) approach achieves significant performance gain, as measured by reduction of the number of iterations for model training. Using point kinetic equations (PKEs) model with six neutron precursor groups, constructed with experimental parameters of the Purdue University Reactor One (PUR-1) research reactor, we generated different RTs with experimentally relevant range of variables. The RTs were characterized using Hausdorff and Fréchet distance. We have demonstrated that pre-training TL-PINN on one RT results in up to two orders of magnitude acceleration in prediction of a different RT. The mean error for conventional PINN and TL-PINN models prediction of neutron densities is smaller than 1%. We have developed a correlation between TL-PINN performance acceleration and similarity measure of RTs, which can be used as a guide for application of TL-PINNs.
22 GENERAL STUDIES OF NUCLEAR REACTORS↗
Magnetism and superconductivity of some Tl-Cu oxides
Many copper oxide based Thallium compounds have now been discovered. In comparison to the Bi-compounds, the Tl-system shows a richer diversity; viz., High Temperature Superconductors (HTSC) can be obtained with either one or two Tl-0 layers (m = 1,2); also, the triple-digit phases are easier to synthesize. The value of d, oxygen stoichiometry, is critical to achieving superconductivity. The Tl system is robust to oxygen loss; Tl may be lost or incorporated by diffusion. A diffusion coefficient equal to 10 ms at 900 C was determined. Both ortho-rhombic and tetragonal structures are evidenced, but HTSC behavior is indifferent to the crystal symmetry. This system has the highest T(sub c) confirmed. T(sub c) generally increases with p, the number of CuO layers, but tends to saturate at p = 3. Zero resistance as high as 125K has been observed. Most of these HTSC's are hole type, but the Ce-doped specimens may be electronic. The magnetic aspects were studied; because in addition to defining the perfectly diamagnetic ground state as in the conventional superconductors, magnetism of the copper oxides show a surprising variety. This is true of both the normal and the superconducting states. Also, due to the large phonon contribution to the specific heat at the high T(sub c) accurate thermal measurement of important parameters such as the sp. heat jump, electronic density of states, D(Ef) and coherence length are uncertain, and thus, are estimated from the magnetic results. Results from the Tl-system CuO, LaBaCuO, 120 and the Bi-CuO compounds are discussed. The emphasis is on the role of magnetism in the TlCuO HTSC, but technological aspects are also pointed out.
Datta, Timir↗