130,653 research outputs found
Progress towards Bell-type polarization experiment with thermal neutrons
No full textExperimental tests of Bell-type inequalities distinguishing between quantum mechanics and local realistic theories remain of considerable interest if performed on massive particles, for which no conclusive result has yet been obtained. Only two-particle experiments may specifically test the concept of spatial nonlocality in quantum theory, whereas single-particle experiments may generally test the concept of quantum noncontextuality. Here we have performed the first Bell-type experiment with a beam of thermal-neutron pairs in the singlet state of spin, as originally suggested by J. S. Bell. These measurements confirm the quantum-theoretical predictions, in agreement with the results of the well-known polarization experiments carried out on optical photons years ago
CALPRO, an unconventional calorimetry approach
No full textWe propose a calorimetry approach unconventional and innovative. The method is based on the measurement of the lateral distribution of charged particles around the shower axis, it has been used for the first time in the energy determination of Extensive Air Showers at very high energy (>100 TeV) with single layer detector, providing an energy determination with resolution of about 10% for energies above 100 TeV. It has some peculiar characteristics which can be summarized in the following three points: (1) measurement of the shower energy by means of a single sampling; (2) calorimetry which renounces the classic concept of containment of the shower; (3) possibility to separate primary masses. In order to extend this technique at lower energies, specific simulations have been performed through GEANT4 in the energy range 100 GeV–10 TeV for different particles
CALPRO—a unconventional calorimetry project
No full textWe propose a unconventional calorimetry approach. The method is based on idea used for the first time in the energy determination of extensive air showers (EAS) at very high energy (> 100 TeV). It has some peculiar characteristics which can be summarized in the following two points: a) measurement of the shower energy by means of a single sampling; b) measurement of the lateral density distribution of charged particles around the shower axis. We studied the validation of this measurement technique to lower energies (100 GeV–10 TeV) by MC calculation
Deuteron photo-disintegration with polarised photons in the energy range 30-50 MeV
No full textThe reaction d(<(gamma)over right arrow>, np) has been studied using the tagged and polarised LADON gamma ray beam at an energy 30-50 MeV to investigate the existence of narrow dibaryonic resonances recently suggested from the experimental measurements in a different laboratory. The beam was obtained by Compton back-scattering of laser light on the electrons of the storage ring ADONE. Photo-neutron yields were measured at five neutron angle nu(n)(c.m.) = 22 degrees, 55.5 degrees, 90 degrees, 125 degrees and 157 degrees in the center of mass system. Our results do not support the existence of such resonances. (C) 1998 Published by Elsevier Science B.V
A CMOS front-end for SiPM devices aimed to TOF applications with adjustable threshold and high dynamical range
No full textIn recent works we presented the results of the characterization and the study of performance of several
Silicon Photomultipliers delivered from MEPHI (Moscow Engineering and Physics Institute) and we
proposed an electrical model of the SiPM to be used in analog simulations for the VLSI design of
the pilot chip with 0:35 mm technology produced. The results of the simulations was also presented.
In this work we present the results of several test performed on the SiPM connected to the pilot chip.
We also describe the prototype board with a micro-controller designed to adjust the parameters of the
chip and to provide an adjustable and temperature controlled power supply to the SiPM. The results of
the tests obtained allow us to refine the circuits design for the next chip. This chip has been developed
inside the ALTCRISS and KLOE collaboratio
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
Commissioning of the new taggers of the KLOE-2 experiment
No full textIn order to fully reconstruct the γγ processes (e+e−→ e+e−γ⋆γ⋆) in the energy region of the φ-meson production, new detectors along the DAΦNE beam line have been installed to detect the scattered e+e−
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Further evidence of antibunching of two coherent beams of fermions
No full textWe describe an experiment confirming the evidence of the antibunching effect on a beam of noninteracting thermal neutrons. The comparison between the results recorded with a high-energy-resolution source of neutrons and those recorded with a broad-energy-resolution source enables us to clarify the role played by the beam coherence in the occurrence of the antibunching effect
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
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