16 research outputs found
High-Intensity and High-Brightness Source of Moderated Positrons Using a Brilliant gamma Beam
Presently large efforts are conducted towards the development of highly
brilliant gamma beams via Compton back scattering of photons from a
high-brilliance electron beam, either on the basis of a normal-conducting
electron linac or a (superconducting) Energy Recovery Linac (ERL). Particularly
ERL's provide an extremely brilliant electron beam, thus enabling to generate
highest-quality gamma beams. A 2.5 MeV gamma beam with an envisaged intensity
of 10^15 s^-1, as ultimately envisaged for an ERL-based gamma-beam facility,
narrow band width (10^-3), and extremely low emittance (10^-4 mm^2 mrad^2)
offers the possibility to produce a high-intensity bright polarized positron
beam. Pair production in a face-on irradiated W converter foil (200 micron
thick, 10 mm long) would lead to the emission of 2 x 10^13 (fast) positrons per
second, which is four orders of magnitude higher compared to strong radioactive
^22Na sources conventionally used in the laboratory.Using a stack of converter
foils and subsequent positron moderation, a high-intensity low-energy beam of
moderated positrons can be produced. Two different source setups are presented:
a high-brightness positron beam with a diameter as low as 0.2 mm, and a
high-intensity beam of 3 x 10^11 moderated positrons per second. Hence,
profiting from an improved moderation efficiency, the envisaged positron
intensity would exceed that of present high-intensity positron sources by a
factor of 100.Comment: 9 pages, 3 figure
PERSPECTIVAS DEL PROCESO DE GLOBALIZACIÓN Y SU INFLUENCIA SOBRE LOS DERECHOS HUMANOS ECONÓMICOS, SOCIALES Y CULTURALES
El escenario internacional se encuentra en constante transformación debido a lo que se ha denominado el proceso de “globalización”. Este afecta las relaciones internaciones interestatales e influye en la vida cotidiana de los individuos. El Derecho Internacional y más específicamente el Derecho Internacional de los Derechos Humanos no es ajeno a este proceso. La investigación afirma que nos encontramos frente a una etapa de transnacionalización de los Derechos Humanos, que permite que los individuos cuenten con mayor protección en ámbitos supranacionales. También hace especial mención a los derechos Económicos Sociales y Culturales, analiza el debate sobre el pluralismo jurídico y la eficacia diferencial. En la metodología empleada se revisan fuentes documentales y se realiza un análisis de algunos derechos particulares previstos en el Pacto de Derechos Económicos, Sociales y Culturales. Los planteamientos permiten afirmar que el proceso de globalización ha determinado la transnacionalización de los Derechos Humanos, surgiendo de dicho fenómeno consecuencias positivas y negativas en cuanto a su cumplimiento
Coherent X-ray imaging and microscopy opportunities with a diffraction-limited Energy Recovery Linac (ERL) synchrotron source
A proposed Energy Recovery Linac (ERL) x-ray source at Cornell would be a 5-7 GeV synchrotron
facility based on the energy-recovery principle with a superconducting linac. Because of its ultra-small round
electron source and ultra-short but flexible bunch structure, the ERL has the potential to produce subpicosecond
ultra-bright diffraction-limited hard x-ray beams that are superior to those from existing storage
rings, and would enable new scientific experiments that are difficult or impossible to perform today. In this paper,
we discuss the transverse coherence properties of the ERL source and show how these properties could
benefit various x-ray microscopy applications that require a highly coherent and intense x-ray beam. These applications
include full coherent illumination of wide-aperture zone-plate optics for scanning x-ray microscopy,
diffraction-limited coherent phase-contrast microscopy and tomography, fully coherent hard x-ray diffraction
microscopy, and large-coherence-area x-ray holography techniques