Search results for "neutron"

Structure of Hybrid Materials Based on Halloysite Nanotubes Filled with Anionic Surfactants

2016

The structures of pristine halloysite nanotubes (HNTs) and ones functionalized by anionic surfactants (sodium dodecanoate and sodium dodecyl sulfate) were investigated by small angle neutron scattering (SANS). These experiments evidenced the structural organization of the surfactants adsorbed onto the HNT cavity and the importance of the surfactant headgroup. Contrast matching experiments were employed in order to mask the dominant scattering effect of the clay hollow nanotubes and to focus on the surfactant organization within the lumen. Further investigation on the mesoscopic structure of the investigated materials was carried out by electric birefringence (EBR), which allowed study of th…

1979

On the theoretical–numerical study of the HEXCALIBER mock-up thermo-mechanical behaviour

2010

Abstract Within the framework of the R&D activities promoted by European Fusion Development Agreement on the Helium-Cooled Pebble Bed Test Blanket Module to be irradiated in ITER, ENEA Brasimone and the Department of Nuclear Engineering of the University of Palermo (DIN) performed intense research activities on the modelling of the thermo-mechanical behaviour of both beryllium and lithiated ceramics pebble beds, that are envisaged to be used, respectively, as neutron multiplier and tritium breeder. In particular, the DIN developed a thermo-mechanical constitutive model for these pebble beds to be validated against the HEXCALIBER mock-up test campaign, carried out at the ENEA HE-FUS3 facilit…

From crystal to glass-like thermal conductivity in crystalline minerals

2015

Équipe 103 : Composés intermétalliques et matériaux hybrides; International audience; The ability of some materials with a perfectly ordered crystal structure to mimic the heat conduction of amorphous solids is a remarkable physical property that finds applications in numerous areas of materials science, for example, in the search for more efficient thermoelectric materials that enable to directly convert heat into electricity. Here, we unveil the mechanism in which glass-like thermal conductivity emerges in tetrahedrites, a family of natural minerals extensively studied in geology and, more recently, in thermoelectricity. By investigating the lattice dynamics of two tetrahedrites of very c…

NEUTRON IRRADIATION EFFECTS IN PZ and PZT THIN FILMS

2005

ABSTRACT Neutron irradiation effects on highly oriented antiferroelectric PbZrO3 (PZ) and ferroelectric PbZr0.53Ti0.47O3 (PZT) thin films are investigated in view of their possible application as a temperature sensitive element in a new bolometer system for fusion devices like ITER. All investigated thin films were prepared by a sol-gel technique and by pulsed laser deposition (PLD) respectively. The dielectric properties were investigated in a frequency range from 1 to 250 kHz and at temperatures up to 400°C, prior to and after irradiation to a neutron fluence of 3 * 1022 m−2 (E > 0.1 MeV). After irradiation, the films were anneald in several steps up to 400°C in order to remove the radiat…

Fractal approach in petrology: combining ultra small angle, small angle and intermediate angle neutron scattering

2000

Ultra small angle neutron scattering (USANS) instruments have recently covered the gap between the size resolution available with conventional intermediate angle neutron scattering and small angle neutron scattering (SANS) instruments on one side and optical microscopy on the other side. New fields of investigations are now open and important areas of material science (ceramics, glass fibers, natural materials) and fundamental physics (phase transition, phase separation and critical phenomena) can be studied in bulk samples with an accuracy previously unobtainable owing to a combination of favourable features of the neutron-matter interaction: high penetrability of neutrons, even cold neutr…

Confirmation of a realistic reactor model for BNCT dosimetry at the TRIGA Mainz

2014

Purpose: In order to build up a reliable dose monitoring system for boron neutron capture therapy (BNCT) applications at the TRIGA reactor in Mainz, a computer model for the entire reactor was established, simulating the radiation field by means of the Monte Carlo method. The impact of different source definition techniques was compared and the model was validated by experimental fluence and dose determinations. Methods: The depletion calculation code ORIGEN2 was used to compute the burn-up and relevant material composition of each burned fuel element from the day of first reactor operation to its current core. The material composition of the current core was used in a MCNP5 model of the in…

Structural, Optical, and Dielectric Investigations of the Relaxor PLZT 9,75/65/35 Ceramics Irradiated by High-Current Pulsed Electron Beam

2003

A comprehensive study of high-current pulsed electron irradiation effects on the structural, optical and dielectric properties of relaxor (Pb (1-x )La x )(Zr 0.65 Ti 0.35 ) 1-x/4 O 3 ceramics with x = 9,75 at.% has been performed for the first time. The electron beam had the following parameters: energy E = 250 keV, current density I = 1000 A/cm 2 , pulse duration τ = 300 ns, beam density -10 15 electrons/cm 2 per pulse. Infrared reflectivity spectra in the region of 100 ÷ 2000 cm -1 were obtained in virgin, irradiated by 1500 pulses and annealed up to 500°C ceramics. The reconstruction of perovskite ABO 3 structure in irradiated samples has been studied by combined use of X-ray diffraction…

Laser light scattering and polydispersity of polymers

1977

The application of lasers to light scattering improves the potentials of elastic scattering, especially in the high molecular weight range and enables the technique of inelastic scattering to be used. For elastic light scattering an experimental arrangement and an evaluation method is described which allows, within appropriate molecular weight ranges, the determination of the ratio Mw/Mn from the experimental scattering function with an accuracy down to 0.02. The newer technique of inelastic light scattering yields the coefficient of translational diffusion D. Besides D, the friction coefficient f is also directly accessible. The basic equations are reported, as well as an application to mi…

<title>Structual changes of the PLZT ceramics irradiated by high-current pulsed electron beam</title>

2003

First time comprehensive study of high-current pulsed electron irradiation effects on the structural, optical and dielectric properties of relaxor (Pb(1-x)Lax)(Zr0.65Ti0.35)1-x/4O3 ceramics with x = 4 and 9.75 at.% have been provided. The electron beam had the following parameters: energy E = 250 keV, current density I = 1000 A/cm2, pulse duration τ = 300 ns, beam density - 1015 electrons/cm2 per pulse. Infrared reflectivity spectra in the region of 100 ÷ 2000 cm-1 were obtained in virgin, irradiated by 1500 pulses. The reconstruction of perovskite ABO3 structure in irradiated samples has been studied by complex use of X-ray and neutron scattering and IR spectroscopy techniques revealing th…