A5077983020- Photorefractive and Nonlinear Optics
- Semiconductor materials and devices
- Silicon Nanostructures and Photoluminescence
- Solid State Laser Technologies
- Nuclear Physics and Applications
- Dark Matter and Cosmic Phenomena
- Nuclear reactor physics and engineering
- Ferroelectric and Piezoelectric Materials
- Semiconductor materials and interfaces
- Ion-surface interactions and analysis
- Silicon and Solar Cell Technologies
- Radiation Detection and Scintillator Technologies
- Glass properties and applications
- Luminescence Properties of Advanced Materials
- Particle Detector Development and Performance
- Thin-Film Transistor Technologies
- Atomic and Subatomic Physics Research
- Photonic and Optical Devices
- X-ray Diffraction in Crystallography
- Integrated Circuits and Semiconductor Failure Analysis
- Nanowire Synthesis and Applications
- Cosmology and Gravitation Theories
- Graphite, nuclear technology, radiation studies
- Magnetic properties of thin films
- X-ray Spectroscopy and Fluorescence Analysis
University of Louisville
2025
University of Lisbon
2013-2024
TARH (Portugal)
2000-2014
Instituto Superior Técnico
2012-2014
Max Planck Institute for Plasma Physics
2010-2011
Max Planck Society
2011
Instituto de Ciencia de Materiales de Madrid
2005
Consejo Superior de Investigaciones Científicas
2005
Leipzig University
1995
University of Stuttgart
1992-1994
We report the final results of Phase II SIMPLE measurements, comprising two run stages 15 superheated droplet detectors each, with second stage including an improved neutron shielding. The analyses include a refined signal analysis, and revised nucleation efficiency based on reanalysis previously reported monochromatic irradiations. combined yield contour minimum ${\ensuremath{\sigma}}_{p}=5.7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}\text{ }\text{ }\mathrm{pb}$ at $35\text{...
Spin tunnel junctions with tunneling magnetoresistance of 36.5%±0.5%, resistance-area product 35±6 kΩ×μm2, and junction area between 6 75 μm2 were fabricated. The barrier height is 2.5±0.3 eV the thickness 7.7±0.3 Å. Large (TMR) values are obtained by vacuum anneal (at temperatures from 100 to 240 °C for over 5 h) prepared as-deposited TMR 21%±1.7%, an 25±6 kΩ×μm2. Two regimes occur during anneal. first one occurs anneals up 200 where resistance increase, but parameters unaltered. second...
Half-biased spin valves have been prepared by ion beam deposition. The magnetoresistance (MR) signal reaches 7.7% and the exchange field is 350 Oe with a coupling of 15 coercivity free layer equal to 4 Oe. [111] texture induced very thin Ta buffer (thickness <10 /spl Aring/) has strong effect in increasing MR field, while decreasing coercivity. blocking temperature MnIr-biased 250/spl deg/C thermal stability study shows that constant up 300/spl deg/C, under consecutive 5-h anneals at each...
Phase II of SIMPLE (Superheated Instrument for Massive ParticLe Experiments) searched astroparticle dark matter using superheated liquid C$_{2}$ClF$_{5}$ droplet detectors. Each generally requires an energy deposition with linear transfer (LET) $\gtrsim$ 150 keV/$\mu$m a liquid-to-gas phase transition, providing intrinsic rejection against minimum ionizing particles order 10$^{-10}$, and reducing the backgrounds to primarily $\alpha$ neutron-induced recoil events. The transition generates...
NaBi(WO4)2 (NBW), NaBi(MoO4)2 (NBMo) and LiBi(MoO4)2 (LBMo) single crystals grown by the Czochralski technique have been doped up to a praseodymium concentration of in crystal. 10 K polarized optical absorption photoluminescence measurements used determine energy position 32, 39 36 Pr3+ Stark levels NBW, NBMo LBMo crystals, respectively. These were labelled with appropriate irreducible representations corresponding C2 local symmetry an average centre. Single-electron Hamiltonians including...
The optoelectronic and structural properties of hydrogenated amorphous silicon-carbon alloys (a-SiC:H) are studied over the entire compositional range carbon content. films prepared using low-power electron-cyclotron resonance (ECR) plasma-enhanced chemical vapor deposition. content was varied by different methane (or ethylene-)-to-silane gas phase ratios introducing ethylene) either remotely into plasma stream or directly through ECR source, together with excitation (hydrogen). Regardless...
Because of the incongruent melting LiYb(MoO4)2 compound at 912 °C, Li2MoO4 and Li2Mo2O7 fluxes have been used to nucleate single crystals this compound. From latter flux, about 1 cm3 pulled by top-seeded solution-growth method. Details on preparation growth procedures are provided. The Li concentration in crystal has assessed using 7Li(p,α)4He nuclear reaction induced protons. [Yb]/[Li] molar composition ratio obtained several samples is 1.01−1.05 range. This result compares well with =...
The temperature and annealing effects on junctions with high (10–13 MΩ μm2) low (25–30 kΩ resistance-area products were studied. Junction tunneling magnetoresistance (TMR) is almost unchanged above 20% up to 200 °C. A sharp reversible TMR decrease observed between 220 °C due the exchange loss in pinning layer. increases from 22% 26% product samples (resistance decreases a factor of 2), 37% 30%) samples, upon anneal 200–230 Rutherford backscattering (RBS) analysis oxygen distribution...
Pure and Er-doped ([Er]crystal≤2.4 × 1020 cm−3), NaBi(WO4)2 (NBW), NaBi(MoO4)2, LiBi(MoO4)2 crystals have been grown by the Czochralski method. The three crystal hosts similar structural optical properties. noncentrosymmetric space group I4¯ (No. 82) crystallographic structure has established through 300 K single-crystal x-ray neutron (for NBW only) diffraction. Er3+ energy levels were determined experimentally simulated in S4 symmetry a crystal-field analysis. With this background, large...
Molybdenum-99 is one of the most important radionuclides for medical diagnostics. In 2015, International Atomic Energy Agency organized a round-robin exercise where participants measured and calculated specific saturation activities achievable 98Mo(n,γ)99Mo reaction. This reaction interest as means to locally, on small scale, produce 99Mo from natural molybdenum. The current paper summarises set experimental results reviews methodology calculating corresponding activities. Activation by...
Neutrino oscillation experiments have proved that neutrinos are massive particles but the assessment of their absolute mass scale is still an outstanding challenge in today particle physics and cosmology.The laboratory dedicated to effective electron-neutrino determination ones based on study single beta decay or electron capture (EC) decay.Exploiting only energy-momentum conservation, this kinematic measurement one which permits estimate neutrino masses without theoretical assumptions...
The luminescence emission of structures containing Ge nanocrystals embedded in a dielectric matrix obtained by dry and wet oxidation polycrystalline SiGe layers has been studied as function the time initial layer thickness. A clear relationship between intensity luminescence, structure sample, formation process parameters that allows us to select appropriate conditions get most efficient established. evolution composition thickness growing oxides remaining during processes characterized...
Any plasma diagnostic in ITER must be able to operate at temperatures excess of 200 °C and neutron loads corresponding 0.1 dpa over its lifetime. To achieve this aim for the bolometer diagnostic, a miniaturized metal resistor detector based on Pt absorbers galvanically deposited SiN membranes is being developed. The first two generations detectors featured up 4.5 μm thick absorbers. Results from laboratory tests are presented characterizing dependence their calibration constants under...
Neutron production yields and energy distributions from (α,n) reactions in light elements were calculated using three different codes (SOURCES, NEDIS USD) compared with the existing experimental data 3.5-10 MeV alpha range. SOURCES display an agreement between measured decay series of 235U, 238U 232Th within ±10% for most materials. The discrepancy increases but still ±20% applies to all materials reliable elemental (the few exceptions are identified). neutron describe data, retrieving very...