126 research outputs found
Highly efficient crystal deflector for channeling extraction of a proton beam from accelerators
The design and performance of a novel crystal deflector for proton beams are
reported. A silicon crystal was used to channel and extract 70 GeV protons from
the U-70 accelerator in Protvino with an efficiency of 85%, as measured for a
beam of ~1e12 protons directed towards crystals of ~2 mm length in spills of ~2
s duration. Experimental data agree with the theoretically predicted Monte
Carlo results for channeling. The technique allows one to manufacture a very
short deflector along the beam direction (2 mm). Consequently, multiple
encounters of circulating particles with the crystal are possible with little
probability of multiple scattering and nuclear interactions per encounter.
Thus, drastic increase in efficiency for particle extraction out of the
accelerator was attained. We show the characteristics of the crystal- deflector
and the technology behind it. Such an achievement is important in devising a
more efficient use of the U-70 accelerator and provides crucial support for
implementing crystal-assisted slow extraction and collimation in other
machines, such as the Tevatron, RHIC, the AGS, the SNS, COSY, and the LHC.Comment: Presented at PAC 2003 (Portland, May 12-16
Crystal Deflector for Highly-efficient Channelling Extraction of a Proton Beam from Accelerators
The design and manufacturing details of a new crystal deflector for proton beams are reported. The technique allows one to manufacture a very short deflector along the beam direction (2 mm). Thanks to that, multiple encounters of circulating particles with the crystal are possible with a reduced probability of multiple scattering and nuclear interactions per encounter. Thus, drastic increase in efficiency for particle extraction out of the accelerator was attained (85%) on a 70-GeV proton beam. We show the characteristics of the crystal-deflector and the technology behind it
Crystal Undulator As A Novel Compact Source Of Radiation
A crystalline undulator (CU) with periodically deformed crystallographic
planes is capable of deflecting charged particles with the same strength as an
equivalent magnetic field of 1000 T and could provide quite a short period L in
the sub-millimeter range. We present an idea for creation of a CU and report
its first realization. One face of a silicon crystal was given periodic
micro-scratches (grooves), with a period of 1 mm, by means of a diamond blade.
The X-ray tests of the crystal deformation have shown that a sinusoidal-like
shape of crystalline planes goes through the bulk of the crystal. This opens up
the possibility for experiments with high-energy particles channeled in CU, a
novel compact source of radiation. The first experiment on photon emission in
CU has been started at LNF with 800 MeV positrons aiming to produce 50 keV
undulator photons.Comment: Presented at PAC 2003 (Portland, May 12-16
Electrical transport mechanisms of Neodymium-doped rare-earth semiconductors
This study reports the electrical properties of Nd-doped cerium oxide (CeO2) films synthesized by microwave assisted hydrothermal using a two-point probe technique. Positron annihilation lifetime spectroscopy studies evidenced that, as the Nd content rises, a structural disorder occurs. This is caused by an increase in oxygen vacancies surrounded with Nd (defective clusters), with the mean lifetime components ranging between 290 and 300 ps. Particle size estimation showed values from 8.6 to 28.9 nm. Along with the increase of neodymium impurities, also the conductivity increases, due to the hopping conduction mechanism between defective species. This gives rise to a response time of only 6 s, turning these materials candidates to realize gas sensor devices. Ab initio investigations showed that the improved electric conduction is boosted mostly by the reduced Nd2+ than the Ce3+, where the oxygen vacancies play a fundamental role.Fil: Vaz, Isabela C. F.. Federal University of Itajubá; BrasilFil: Macchi, Carlos Eugenio. Universidad Nacional del Centro de la Provincia de Buenos Aires; Argentina. Provincia de Buenos Aires. GobernaciĂłn. ComisiĂłn de Investigaciones CientĂficas; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Somoza, Alberto Horacio. Universidad Nacional del Centro de la Provincia de Buenos Aires; Argentina. Provincia de Buenos Aires. GobernaciĂłn. ComisiĂłn de Investigaciones CientĂficas; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Rocha, Leandro S. R.. Universidade Federal do SĂŁo Carlos; BrasilFil: Longo, Elson. Universidade Federal do SĂŁo Carlos; BrasilFil: Cabral, Luis. Universidade Estadual de Campinas; BrasilFil: da Silva, Edison Z.. Universidade Estadual de Campinas; BrasilFil: Simões, Alexandre Zirpoli. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Zonta, Giulia. UniversitĂ di Ferrara; ItaliaFil: Malagu, Cesare. UniversitĂ di Ferrara; ItaliaFil: Desimone, Paula Mariela. Universidad Nacional de Mar del Plata; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y TecnologĂa de Materiales. Universidad Nacional de Mar del Plata. Facultad de IngenierĂa. Instituto de Investigaciones en Ciencia y TecnologĂa de Materiales; ArgentinaFil: Ponce, Miguel Adolfo. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y TecnologĂa de Materiales. Universidad Nacional de Mar del Plata. Facultad de IngenierĂa. Instituto de Investigaciones en Ciencia y TecnologĂa de Materiales; Argentina. Universidad Nacional de Mar del Plata; ArgentinaFil: Moura, Francisco. Federal University of Itajubá; Brasi
The Italian multiple sclerosis register
The past decade has seen extraordinary increase in worldwide availability of and access to several large multiple sclerosis (MS)
databases and registries. MS registries represent powerful tools to provide meaningful information on the burden, natural history,
and long-term safety and effectiveness of treatments. Moreover, patients, physicians, industry, and policy makers have an active
interest in real-world observational studies based on register data, as they have the potential to answer the questions that are most
relevant to daily treatment decision-making. In 2014, the Italian MS Foundation, in collaboration with the Italian MS clinical
centers, promoted and funded the creation of the Italian MS Register, a project in continuity with the existing Italian MS Database
Network set up from 2001. Main objective of the Italian MS Register is to create an organized multicenter structure to collect data
of all MS patients for better defining the disease epidemiology, improving quality of care, and promoting research projects in
high-priority areas. The aim of this article is to present the current framework and network of the Italian MS register, including the
methodology used to improve the quality of data collection and to facilitate the exchange of data and the collaboration among
national and international groups
The Italian multiple sclerosis register
The past decade has seen extraordinary increase in worldwide availability of and access to several large multiple sclerosis (MS) databases and registries. MS registries represent powerful tools to provide meaningful information on the burden, natural history, and long-term safety and effectiveness of treatments. Moreover, patients, physicians, industry, and policy makers have an active interest in real-world observational studies based on register data, as they have the potential to answer the questions that are most relevant to daily treatment decision-making. In 2014, the Italian MS Foundation, in collaboration with the Italian MS clinical centers, promoted and funded the creation of the Italian MS Register, a project in continuity with the existing Italian MS Database Network set up from 2001. Main objective of the Italian MS Register is to create an organized multicenter structure to collect data of all MS patients for better defining the disease epidemiology, improving quality of care, and promoting research projects in high-priority areas. The aim of this article is to present the current framework and network of the Italian MS register, including the methodology used to improve the quality of data collection and to facilitate the exchange of data and the collaboration among national and international groups
Atrial Flutter in Patient With Critical COVID-19: Beneficial Effects of Rhythm Control on Respiratory Distress
We report the case of a patient critically ill with coronavirus disease–2019 (COVID-19) in which atrial flutter with high ventricular response rate occurred, contributing to worsening of the respiratory distress. After failure of noninvasive rate and rhythm control strategies, successful transcatheter ablation was performed and the respiratory distress of the patient improved. (Level of Difficulty: Beginner.
Spectroscopic and electrical evidence of transition to nanostructured behaviour in SnO2
SnO2 sensors with two different average grain size showed diverse behaviors through electrical and spectroscopic characterizations. In the case of direct current electrical responses, the increase in conductance for the same temperature rise was, on average, about three times larger for larger grained samples. Impedance spectroscopic plots were obtained in dry air and were fitted with the same equivalent circuit for the two granulometries, showing important differences in the fitting parameters. The two techniques present interesting analogies for the same temperature variations. We interpreted this behaviour in terms of barrier modulation through gas chemisorption and oxygen indiffusion, also taking into account of tunneling contribution to conductivity
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