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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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96 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Crystal growth, physical and optical properties of TlSr 2 Cl 5 and TlSr 2 Br 5

Small diameter (Ø 16 mm) TlSr 2 Cl 5 and TlSr 2 Br 5 crystals were grown by the Vertical Bridgman method. X-ray diffraction measurements show that both have the monoclinic crystal structure with space group P21/c. TlSr 2 Cl 5 and TlSr 2 Br 5 have a density of 4.14 g/cm 3 and 5.03 g/cm 3 , respectively. The effective Z of TlSr 2 Cl 5 and TlSr 2 Br 5 is 63.7 and 58.6, respectively. Radioluminescence spectra of TlSr 2 Cl 5 and TlSr 2 Br 5 feature a broad emission band peaking at 440 and 445 nm, respectively. As a result the light yield of TlSr 2 Cl 5 and TlSr 2 Br 5 was estimated to be 17,000 and 45,000 ph/MeV, respectively.

36 MATERIALS SCIENCE↗
DOE OSTI2020

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↗
DOE OSTI2021

Crystal growth, density functional theory, and scintillation properties of Tl 3 LnCl 6 :Ce 3+ and TlLn 2 Cl 7 :Ce 3+ (Ln = Y, Gd)

In this paper we report on the crystal growth, density functional theory (DFT) calculations and scintillation properties of Tl 3 LnCl 6 :Ce and TlLn 2 Cl 7 :Ce(Ln = Y, Gd). Crystals were grown by the Vertical Bridgman technique up to 16 mm in diameter and 25 mm long. Crystals of Tl 3 YCl 6 :Ce and Tl 3 GdCl 6 :Ce belong to the family of the Nesohalides which have the monoclinic crystal structure. Crystals of TlY 2 Cl 7 :Ce and TlGd 2 Cl 7 :Ce belong to the family of the Phyllohalides which have either the monoclinic or the orthorhombic crystal structure. We report the light yields of these Nesohalides and Phyllohalides are typically on the order of 35,000–40,000 ph/MeV.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2025

Crystal Growth, Optical and Scintillation Properties of Eu 2+ -doped TlSr 2 Br 5

Crystals of undoped and Eu 2+ -doped TlSr 2 Br 5 of up to 16 mm in diameter and 50 mm in length were grown by the Vertical Bridgman technique. TlSr 2 Br 5 has the monoclinic crystal structure with space group P21/c. Its density and Z eff are 5.03 g/cm 3 and 58.6, respectively. Radioluminescence spectra of undoped and Eu 2+ -doped TlSr 2 Br 5 feature a broad emission band peaking at about 440 nm for undoped and 520 nm for Eu 2+ -doped crystals. The light yield of undoped TlSr 2 Br 5 is 42,000 ph/MeV, which increases to 55,000 ph/MeV for Eu 2+ -doped crystals. The energy resolution at 662 keV ( 137 Cs) is about 5 – 6% (FWHM). As a result, the scintillation decay of undoped and Eu 2+ -doped TlSr 2 Br 5 is of the order of 100s of nanoseconds.

Bridgman technique↗
DOE OSTI2025

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↗
DOE OSTI2023

Double-Layer Kagome Metals Pt 3 Tl 2 and Pt 3 In 2

The connectivity and inherent frustration of the kagome lattice can produce interesting electronic structures and behaviors in compounds containing this structural motif. Here we report the properties of Pt 3 X 2 (X = In and Tl) that adopt a double-layer kagome net structure related to that of the topologically nontrivial high-temperature ferromagnet Fe 3 Sn 2 and the density wave hosting compound V 3 Sb 2 . We examined the structural and physical properties of single crystal Pt 3 Tl 2 and polycrystalline Pt 3 In 2 using X-ray and neutron diffraction, magnetic susceptibility, heat capacity, and electrical transport measurements, along with density functional theory calculations of the electronic structure. Our calculations show that Fermi levels lie in pseudogaps in the densities of states with several bands contributing to transport, and this is consistent with our Hall effect, magnetic susceptibility, and heat capacity measurements. Although electronic dispersions, characteristic of simple kagome nets with nearest-neighbor hopping, are not clearly seen, likely due to the extended nature of the Pt 5d states, we do observe moderately large and non-saturating magnetoresistance values and quantum oscillations in the magnetoresistance and magnetization associated with the kagome nets of Pt.

36 MATERIALS SCIENCE↗