Search results for " NEUTRON"
showing 10 items of 618 documents
Applied neutron tomography in modern archaelogy
2007
The use of neutron tomography for archaeometric purposes is quite a new technique. The property of neutron to transmit easily large, dense samples is of great importance in modern archaeology. The three-dimensional visualisation of the inner structure of samples of archaeological interest helps to make suggestions about the technological process of manufacturing or reveals information about the origins of delivering of noble materials used in ancient masterpieces. Another application field in modern archaeology is the non-destructive inspection of the quality of specimen conservation where the neutron tomography allows visualization of impregnation solutions in wood or metal matrices. The h…
Time-domain effective-one-body gravitational waveforms for coalescing compact binaries with nonprecessing spins, tides and self-spin effects
2018
We present TEOBResumS, a new effective-one-body (EOB) waveform model for nonprecessing (spin-aligned) and tidally interacting compact binaries.Spin-orbit and spin-spin effects are blended together by making use of the concept of centrifugal EOB radius. The point-mass sector through merger and ringdown is informed by numerical relativity (NR) simulations of binary black holes (BBH) computed with the SpEC and BAM codes. An improved, NR-based phenomenological description of the postmerger waveform is developed.The tidal sector of TEOBResumS describes the dynamics of neutron star binaries up to merger and incorporates a resummed attractive potential motivated by recent advances in the post-Newt…
TAGS measurements for neutrino physics and applications
2017
En la actualidad un gran número de temas de interés en Física Nuclear continúan planteando interrogantes fundamentales. Una de las fuentes de información más esclarecedoras es el proceso de la desintegración beta. Gracias al estudio experimental de este fenómeno en núcleos alejados de la estabilidad, es posible extraer valiosa información sobre estructura nuclear. En esa línea, esta tesis se centra en la determinación de las intensidades beta que pueblan los estados excitados del núcleo hijo en la desintegración beta de núcleos exóticos de gran interés. Para ello se ha utilizado la técnica de Espectroscopía gamma de Absorción Total (TAGS, por sus siglas en inglés), basada en el uso de grand…
Valutazione della fluenza di neutroni di origine cosmica a livello del suolo
2013
Lo studio degli effetti delle radiazioni neutroniche sul funzionamento dei componenti che fanno parte dei più comuni sistemi elettronici comporta lo studio della fluenza neutronica di origine cosmica a livello del suolo. Infatti la sorgente primaria dei neutroni in atmosfera è principalmente individuabile nell’interazione tra i raggi cosmici di origine solare ed i vari strati dell’atmosfera. Il campo neutronico pertanto non è dunque costante ma dipende fortemente dai cicli di attività solare. In questo lavoro sono presentati i risultati di due cicli di misurazioni del “dose rate” da neutroni nei periodi 21-28 Febbraio e 29 Febbraio-7 Marzo 2012. La strumentazione utilizzata è costituita dal…
Lipid multilayered particles: the role of chitosan on structure and morphology
2010
Multilayered nanovectors made up from a controlled binary lipid mixture (POPC and DMPS) and trimethyl chitosan (TMC) have been prepared and characterized by light- and small angle neutron scattering. The morphology and the multilayer structure of the particle outer shell has been described in detail. By varying the amount of TMC in the starting solution it is possible to tune the overall surface particle charge as well as its multilamellarity. In this way the drug loading/release properties of the particles can be controlled. Therefore the use of controlled POPC/DMPS mixtures can be a valid alternative to commercial lecithin to obtain nanovectors with specific release properties.
Small-angle neutron scattering from lecithin reverse micelles
1996
Abstract We report new results of small-angle neutron scattering from cyclohexane- d 12 /lecithin/water micellar solutions, performed as a function of the water content, w 0 , the temperature, T and the dispersed-phase volume fraction, ф. The data from dilute samples can be interpreted in terms of the existence of giant cylindrical reverse micelles, in good agreement with the current idea of an unlimited micellar growth with ф. In contrast, the appearance of a sharp interference maximum at high concentrations ( ф > 0.15 ) suggests that the current hypothesis of a gel structure interpreted as a random network of entangled micelles can be assumed to be incorrect, and that there must be some c…
Fingerprinting white marbles of archaeometric interest by means of combined SANS and USANS
2007
We have performed a series of USANS and SANS measurements on a selected group of marble samples characterized by similar chemical composition but wide range of known metamorphic conditions. With these samples we start the building up of a data base in an attempt to correlate metamorphism and mesoscopic structure of white marbles. Experimental data have been analysed in terms of a hierarchical model. The present data highlight the importance of the structure at meso scale in identifying the provenance of the marble samples. A remarkable simple relation between the model parameters and the metamorphic degree has been found. This curve might represent a master curve to allow fingerprinting of …
Study of the response of phenol compounds exposed to gamma photons and neutrons for Electron Spin Resonance dosimetry
2014
Broad-band Spectral Evolution of Scorpius X-1 along its Color-Color Diagram
2007
We analyze a large collection of RXTE archive data from April 1997 to August 2003 of the bright X-ray source Scorpius X-1 in order to study the broadband spectral evolution of the source for different values of the inferred mass accretion rate by studying energy spectra from selected regions in the Z-track of its Color-Color Diagram. A two-component model, consisting of a soft thermal component interpreted as thermal emission from an accretion disk and a thermal Comptonization component, is unable to fit the whole 3--200 keV energy spectrum at low accretion rates. Strong residuals in the highest energy band of the spectrum require the addition of a third component that can be fitted with a …
Combined TL and 10B-alanine ESR dosimetry for BNCT
2004
The dosimetric technique described in this paper is based on electron spin resonance (ESR) detectors using an alanine-boric compound acid enriched with 1 0 B, and beryllium oxide thermoluminescent (TL) detectors; with this combined dosimetry, it is possible to discriminate the doses due to thermal neutrons and gamma radiation in a mixed field. Irradiations were carried out inside the thermal column of a TRIGA MARK II water-pool-type research nuclear reactor, also used for Boron Neutron Capture therapy (BNCT) applications, with thermal neutron fluence from 10 9 to 10 1 4 n t h cm - 2 . The ESR dosemeters using the alanine-boron compound indicated ESR signals about 30-fold stronger than those…