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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Nuclear Data Sheets for A=140☆

The 2006 evaluation of A=140 was updated using experimental results published before November 2018 from the various reaction and decay studies leading to the nuclei {sup 140}Sb, {sup 140}Te, {sup 140}I, {sup 140}Xe, {sup 140}Cs, {sup 140}Ba, {sup 140}La, {sup 140}Ce, {sup 140}Pr, {sup 140}Nd, {sup 140}Pm, {sup 140}Sm, {sup 140}Eu, {sup 140}Gd, {sup 140}Tb, {sup 140}Dy, {sup 140}Ho. These data are summarized and presented, together with adopted level schemes and properties.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2014

Determination of {sup 140}La fission product interference factor for INAA

Instrumental Neutron Activation Analysis (INAA) is a technique widely used to determine the concentration of several elements in several kinds of matrices. However if the sample of interest has higher relative uranium concentration the obtained results can be interfered by the uranium fission products. One of these cases that is affected by interference due to U fission is the {sup 140}La, because this radioisotope used in INAA for the determination of concentration the La is also produced by the {sup −}β of {sup 140}Ba, an uranium fission product. The {sup 140}La interference factor was studied in this work and a factor to describe its time dependence was obtained.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

The magnetic behavior of the intermetallic compound NdMn{sub 2}Ge{sub 2} studied by magnetization and hyperfine interactions measurements

The magnetic behavior of the intermetallic compound NdMn{sub 2}Ge{sub 2} was investigated by bulk magnetization measurements and measurements of hyperfine interactions using perturbed γ–γ angular correlation (PAC) spectroscopy. Magnetization measurements indicate the presence of four magnetic transitions associated with the Mn and Nd magnetic sublattices. At high temperatures, magnetic measurements show a change in the slope of the magnetization due to an antiferromagnetic transition around T{sub N} ∼ 425 K and a well defined ferromagnetic transition at T{sub C} ∼ 320 K. Moreover, at ∼210 K a peak is observed in the magnetization curve, which is assigned to the reorientation of the Mn spin, and at ∼25 K an increase in the magnetic moment is also observed, which is ascribed to the ordering of Nd ions. PAC measurements using {sup 140}La({sup 140}Ce) and {sup 111}In({sup 111}Cd) probe nuclei allowed the determination of the temperature dependence of the magnetic hyperfine field (B{sub hf}) at Nd and Mn sites, respectively. PAC results with {sup 111}Cd probe nuclei at Mn sites show that the dependence of B{sub hf} with temperature follows the expected behavior for the host magnetization associated with the magnetic ordering of Mn ions. From these results, the antiferromagnetic transition followed by a ferromagnetic ordering is clearly observed. PAC results with {sup 140}Ce probe nuclei at Nd sites, however, showed a strong deviation from the Brillouin function, which is attributed to the Ce 4f-electron contribution to B{sub hf}.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Magnetic behavior of La-doped Fe{sub 3}O{sub 4} studied by perturbed angular correlation spectroscopy with {sup 111}Cd and {sup 140}Ce

In this paper, the local magnetic properties of La-doped Fe{sub 3}O{sub 4} (5% and 10%) bulk and Nanoparticles (NPs) samples were studied by measuring hyperfine interactions in a wide range of temperature from 10 to 900 K with perturbed γ-γ angular correlation spectroscopy using {sup 111}In({sup 111}Cd) and {sup 140}La({sup 140}Ce) as probe nuclei. Results for the temperature dependence of the magnetic hyperfine field (B{sub hf}) for bulk and NP samples, pure and doped with La show that its behavior follows a second order Brillouin-like transition from which the Curie temperature (T{sub C}) was determined (T{sub C} ∼ 855 K). Results also show two different regions in NP samples: the core where a minor fraction of probe nuclei with well defined magnetic dipole frequency was observed and the shell where a major fraction with broad distributed electric quadrupolar frequency (surface effect in NP) was observed. The Verwey transition T{sub V} ∼ 120 K, due the order disorder phase, was also observed in all samples. The results are discussed in terms of the magnetic exchange interaction between Fe{sup 2+} and Fe{sup 3+} ions in the two regions of NP.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2011

Investigation of the neutron activation of endohedral rare earth metallofullerenes

Endohedral lanthanide metallofullerenes and their water-soluble biocompatible derivatives have been synthesized. The effect that fast-neutron irradiation has on the stability and nuclear physical properties of endohedral metallofullerenes that are used as magnetocontrast materials ({sup 46}Sc, {sup 140}La, {sup 141}Nd, {sup 153}Sm, {sup 152}Eu, {sup 154}Eu, {sup 153}Sm, {sup 160}Tb, {sup 169}Yb, {sup 170}Tm (isomers I and III), and {sup 177}Lu) is studied. Our hypothesis, according to which carbon-shell relaxation is based on the fast nonradiative processes of an electron shake-off type, is confirmed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Level structure of light neutron-rich La isotopes beyond the 𝑁 = 82 shell closure

Here, the high spin excited states of Lanthanum isotopes 140–143 La, above the 𝑁 = 82 closed shell, were populated in fission reactions. The prompt 𝛾-ray transitions were measured using two complementary methods: (a) in coincidence with the isotopically identified fragments produced in the fission of the 238 U + 9 Be system using the Variable Mode Spectrometer (VAMOS++) and the Advanced Gamma Tracking Array (AGATA) spectrometer, and (b) high statistics threefold 𝛾−𝛾−𝛾 and fourfold 𝛾−𝛾−𝛾−𝛾 coincidence data from the spontaneous fission of 252 Cf using the Gammasphere. This work reports the first identification of a pair of parity doublet structures in 143 La and the new high spin level structure in 140–142 La from prompt 𝛾-ray spectroscopy. The level structures are interpreted in terms of the systematics of neighboring odd-𝑍 nuclei above the 𝑍 = 50 shell closure and large-scale shell model calculations. The present results indicate the presence of stable octupole deformation in 143 La. The excitation energy pattern and their comparison with neighboring isotones, moving away from the 𝑁 = 82 closed shell, point towards a transition from single-particle structures to an alternating parity rotational band structure in the La isotopic chain.

Navin, A. [Centre National de la Recherche Scienti↗
DOE OSTI2025

𝛾-ray spectroscopy of 140 La decay for nuclear forensics applications

140 La is an important isotope in nuclear forensics. It is typically paired with 140 Ba as a chronometer for dating nuclear events. Here, in this work, we report the results of two measurements performed to fully characterize the decay scheme of 140 La. The experiments were performed using the Gammasphere array at Argonne National Laboratory and the CLARION2 array at Florida State University. Sources of 140 La were produced through neutron irradiation of natural lanthanum (99.9% 139 La) in the University of Massachusetts Lowell research reactor. We identify a total of 40 transitions, three of which were not previously reported. An angular correlation analysis was conducted confirming current literature 𝐽 assignments and mixing ratios. By considering all data available in the literature, we provide new recommended values for the intensities of the strongest transitions commonly used in applications.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2012

Sol–gel synthesis and electrical characterization of Bi{sub 3.25}La{sub 0.75}Ti{sub 3}O{sub 12} thin films

Graphical abstract: Display Omitted Highlights: ► Bi{sub 3.25}La{sub 0.75}Ti{sub 3}O{sub 12} (BLT) thin films on Pt/TiO{sub 2}/SiO{sub 2}/Si substrates prepared by sol–gel. ► Ethylacetoacetate (EAA) used as a replacement for highly toxic 2-methoxyethanol. ► 0.4 μm thick BLT film has 2P{sub r} ∼ 21 μC/cm{sup 2} and 2E{sub c} of ∼195 kV/cm at 300 kV/cm, εr = 140 and tan δ = 0.025, 1 kHz. ► BLT films with improved dielectric response when prepared form ethylacetoacetate (EAA). -- Abstract: Lanthanum bismuth titanate (Bi{sub 3.25}La{sub 0.75}Ti{sub 3}O{sub 12}) (BLT) thin films on Pt/TiO{sub 2}/SiO{sub 2}/Si substrates were prepared by sol–gel using ethylacetoacetate (EAA) as a replacement for the highly toxic 2-methoxyethanol. EAA is used as a modifier to stabilize the metal alkoxide. At 450 °C films are amorphous. After annealing at 650 °C films are crystalline and present good dielectric and ferroelectric properties. A 0.4 μm thick BLT film exhibits 2P{sub r} of ∼21 μC/cm{sup 2} and 2E{sub c} of ∼195 kV/cm at 300 kV/cm. The dielectric constant and dielectric losses of these BLT films at 1 kHz are 140 and 0.025, respectively.

36 MATERIALS SCIENCE↗
DOE OSTI2024

First study of the $^{139}\text{Ba}(n,y)^{140}\text{Ba}$ reaction to constrain the conditions for the astrophysical $\mathcal{i}$ process

New astronomical observations point to a nucleosynthesis picture that goes beyond what was accepted until recently. The intermediate “i” process was proposed as a plausible scenario to explain some of the unusual abundance patterns observed in metal-poor stars. The most important nuclear physics properties entering i-process calculations are the neutron-capture cross sections and they are almost exclusively not known experimentally. In this report we provide the first experimental constraints on the 139 Ba(n,γ) 140 Ba reaction rate, which is the dominant source of uncertainty for the production of lanthanum, a key indicator of i-process conditions. This is an important step towards identifying the exact astrophysical site of stars carrying the i-process signature.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2012

Measurement of the keV-neutron capture cross section and capture gamma-ray spectrum of isotopes around N=82 region

The keV-neutron capture cross section and capture {gamma}-ray spectra of nuclides with a neutron magic number N= 82, {sup 139}La and {sup 142}Nd, were newly measured by the time-of-flight method. Capture {gamma}-rays were detected with an anti-Compton NaI(T1) spectrometer, and the pulse-height weighting technique was applied to derive the neutron capture cross section. The results were provided with our previous measurements of other nuclides around N= 82, {sup 140}Ce, {sup 141}Pr, {sup 143}Nd and {sup 145}Nd.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2017

Fission Product Yields from 232Th, 238U, and 235U Using 14 MeV Neutrons

Neutron-induced fission yield studies using deuterium-tritium fusion-produced 14 MeV neutrons have not yet directly measured fission yields from fission products with half-lives on the order of seconds (far from the line of nuclear stability). Fundamental data of this nature are important for improving and validating the current models of the nuclear fission process. Cyclic neutron activation analysis (CNAA) was performed on three actinide targets–thorium-oxide, depleted uranium metal, and highly enriched uranium metal–at the University of Michigan's Neutron Science Laboratory (UM-NSL) using a pneumatic system and Thermo-Scientific D711 accelerator-based fusion neutron generator. This was done to measure the fission yields of short-lived fission products and to examine the differences between the delayed fission product signatures of the three actinides. The measured data were compared against previously published results for 89Kr, -90, and -92 and 138Xe, -139, and -140. The average percent deviation of the measured values from the Evaluated Nuclear Data Files VII.1 (ENDF/B-VII.1) for thorium, depleted-uranium, and highly-enriched uranium were -10.2%, 4.5%, and -12.9%, respectively. In addition to the measurements of the six known fission products, 23 new fission yield measurements from 84As to 146La are presented.

Pierson, Bruce D.↗
DOE OSTI2014

Charge disproportionation in La{sub 1-x}Ca{sub x}FeO{sub 3−δ} (x = 0.4 and 0.5) investigated by mechanical spectroscopy

The nature of charge disproportionation in orthorhombic lanthanum orthoferrites La{sub 1-x}Ca{sub x}FeO{sub 3-δ} (x = 0.4 and 0.5) has been investigated by kilohertz mechanical spectroscopy. Contrast to rhombohedral La{sub 1-x}Sr{sub x}FeO{sub 3-δ} (x = 0.5), no elastic softening was observed in La{sub 1-x}Ca{sub x}FeO{sub 3-δ} above charge disproportionation. This different behavior of elastic modulus in La{sub 1-x}Ca{sub x}FeO{sub 3-δ} and La{sub 1-x}Sr{sub x}FeO{sub 3-δ} unveils the implicit orbital effect. Below charge disproportionation, an internal friction peak around 140 K was observed in La{sub 1-x}Ca{sub x}FeO{sub 3-δ}, which is similar to that in La{sub 1-x}Sr{sub x}FeO{sub 3-δ}. This peak is ascribed to an elastic manifestation of charge freezing and can be used as an indirect indication of CD in doped LaFeO{sub 3}.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2011

Thick lanthanum zirconate buffer layers from water-based precursor solutions on Ni-5%W substrates

In this work, water-based precursor solutions suitable for dip-coating of thick La{sub 2}Zr{sub 2}O{sub 7} (LZO) buffer layers for coated conductors on Ni-5%W substrates were developed. The solutions were prepared based on chelate chemistry using water as the main solvent. The effect of polymer addition on the maximum crack-free thickness of the deposited films was investigated. This novel solution preparation method revealed the possibility to grow single, crack-free layers with thicknesses ranging 100-280 nm with good crystallinity and an in-plane grain misalignment with average FWHM of 6.55{sup o}. TEM studies illustrated the presence of nanovoids, typical for CSD-LZO films annealed under Ar-5%H{sub 2} gas flow. The appropriate buffer layer action of the film in preventing the Ni diffusion was studied using XPS. It was found that the Ni diffusion was restricted to the first 30 nm of a 140 nm thick film. The surface texture of the film was improved using a seed layer. - Graphical abstract: Thick LZO buffer layers from water-based precursor solutions were synthesized and their crystallinity, microstructure and buffer layer action were studied. The buffer layer action of the LZO layer was substantial to restrict the Ni penetration within 30 nm of a 140 nm thick film. Highlights: > LZO buffer layers with high thicknesses for use in coated conductors were prepared. > Prepared from water-based solutions. > Polymeric PVP increases the crack-free critical thickness of thick films. > Thick films showed good barrier action against Ni penetration. > Seed layers promote epitaxial growth of thick layers.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2011

Magnetic state of the structural separated anion-deficient La{sub 0.70}Sr{sub 0.30}MnO{sub 2.85} manganite

The results of neutron diffraction studies of the La{sub 0.70}Sr{sub 0.30}MnO{sub 2.85} compound and its behavior in an external magnetic field are stated. It is established that in the 4-300 K temperature range, two structural perovskite phases coexist in the sample, which differ in symmetry (groups R3-bar c and I4/mcm). The reason for the phase separation is the clustering of oxygen vacancies. The temperature (4-300 K) and field (0-140 kOe) dependences of the specific magnetic moment are measured. It is found that in zero external field, the magnetic state of La{sub 0.70}Sr{sub 0.30}MnO{sub 2.85} is a cluster spin glass, which is the result of frustration of Mn{sup 3+}-O-Mn{sup 3+} exchange interactions. An increase in external magnetic field up to 10 kOe leads to fragmentation of ferromagnetic clusters and then to an increase in the degree of polarization of local spins of manganese and the emergence of long-range ferromagnetic order. With increasing magnetic field up to 140 kOe, the magnetic ordering temperature reaches 160 K. The causes of the structural and magnetic phase separation of this composition and formation mechanism of its spin-glass magnetic state are analyzed.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Lasing of Some Red Laser Dyes in Annealed Silica Xerogel

The spectral and energy characteristics of generation in the red spectral region 650–720 nm were measured and analyzed for three laser dyes in preliminarily annealed SiO{sub 2} xerogel matrices under laser excitation λ{sub p} = 588 nm in a nonselective cavity. The specific laser-energy output for two of them (LK678 and Ox170) in the matrices was 10–13% higher than in MeOH. NBA dye in the matrix generated two laser radiation bands in the 700–720 nm region with pumping E{sub p} ≥ 80 mJ whereas its generation threshold in MeOH exceeded the maximum pumping energy of 140 mJ so that NBA generation was not observed. Laser emission spectra of the studied matrices in a nonselective cavity were red-shifted by ~1000 cm{sup –1} from the fluorescence maximum. Such a shift could improve the characteristics of biosensors based on these matrices.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Dynamic magnetic interaction in La{sub 2/3}Sr{sub 1/3}MnO{sub 3}/BiFeO{sub 3} heterostructure

The La{sub 2/3}Sr{sub 1/3}MnO{sub 3}/BiFeO{sub 3} (LSMO/BFO) heterostructure is studied as probed by temperature-dependent ferromagnetic resonance (FMR). Consistent with the structure analysis, two FMR modes are found for both a single LSMO layer and a LSMO/BFO bilayer grown on DyScO{sub 3}, corresponding to the strained and relaxed phases of LSMO. The FMR linewidth intensity vs temperature curve shows two maxima at 200 K and 140 K in the strained phase of LSMO/BFO bilayer, which is related to the magnetic excitations in BFO. Our results demonstrate a dynamic spin interaction between LSMO and BFO, suggesting an effective route to manipulate the magnetic properties of oxide heterostructures.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Characterizing the Distribution of Microwave Surface Resistance of HTS Film Based on Metal Ring

This paper presents a novel method for measuring the microwave surface resistance distribution of high-temperature superconducting thin films by a dielectric resonator with a metal ring. After calibration, the effect of metal ring loss on measurement accuracy is negligible. The measurement resolution is determined by the internal diameter of the metal ring, which makes the design of the device more flexible. Therefore, measurement with high resolution and convenience can be achieved simultaneously by using a metal ring with proper size and operating at a relatively low frequency. A test device working at 32 GHz with TE{sub 01(1 + δ)} mode was developed. Its resolution is a circular area with a diameter of 5 mm and an area of 19.6 mm{sup 2}. The unloaded quality factor of the test device is more than 140,000, when it is loaded by the calibration cavity. The test device has a relative uncertainty of less than 6%, which complies with the uncertainty (20%) specified by the international standard for the microwave surface resistance measurement of high-temperature superconducting (HTS) thin film. The surface resistance distribution of a 2-in. YBCO/LAO/YBCO superconducting film sample was measured by this test device.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2016

Optical evidence of quantum rotor orbital excitations in orthorhombic manganites

In magnetic compounds with Jahn–Teller (JT) ions (such as Mn{sup 3+} or Cu{sup 2+}), the ordering of the electron or hole orbitals is associated with cooperative lattice distortions. There the role of JT effect, although widely recognized, is still elusive in the ground state properties. Here we discovered that, in these materials, there exist excitations whose energy spectrum is described in terms of the total angular momentum eigenstates and is quantized as in quantum rotors found in JT centers. We observed features originating from these excitations in the optical spectra of a model compound LaMnO{sub 3} using ellipsometry technique. They appear clearly as narrow sidebands accompanying the electron transition between the JT split orbitals at neighboring Mn{sup 3+} ions, displaying anomalous temperature behavior around the Néel temperature T{sub N} ≈ 140 K. We present these results together with new experimental data on photoluminescence found in LaMnO{sub 3}, which lend additional support to the ellipsometry implying the electronic-vibrational origin of the quantum rotor orbital excitations. We note that the discovered orbital excitations of quantum rotors may play an important role in many unusual properties observed in these materials upon doping, such as high-temperature superconductivity and colossal magnetoresistance.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗