513 research outputs found
Review of recent experimental progresses in Foundations of Quantum Mechanics and Quantum Information obtained in Parametric Down Conversion Experiments at IENGF
We review some recent experimental progresses concerning Foundations of
Quantum Mechanics and Quantum Information obtained in Quantum Optics Laboratory
"Carlo Novero" at IENGF.
More in details, after a short presentation of our polarization entangled
photons source (based on precise superposition of two Type I PDC emission) and
of the results obtained with it, we describe an innovative double slit
experiment where two degenerate photons produced by PDC are sent each to a
specific slit. Beyond representing an interesting example of relation between
visibility of interference and "welcher weg" knowledge, this configuration has
been suggested for testing de Broglie-Bohm theory against Standard Quantum
Mechanics. Our results perfectly fit SQM results, but disagree with dBB
predictions.
Then, we discuss a recent experiment addressed to clarify the issue of which
wave-particle observables are really to be considered when discussing wave
particle duality. This experiments realises the Agarwal et al. theoretical
proposal, overcoming limitations of a former experiment.
Finally, we hint to the realization of a high-intensity
high-spectral-selected PDC source to be used for quantum information studies
Swift observations of GRB050904: the most distant cosmic explosion ever observed
Swift discovered the high redshift (z=6.29) GRB050904 with the Burst Alert
Telescope (BAT) and began observing with its narrow field instruments 161 s
after the burst onset. This gamma-ray burst is the most distant cosmic
explosion ever observed. Because of its high redshift, the X-ray Telescope
(XRT) and BAT simultaneous observations provide 4 orders of magnitude of
spectral coverage (0.2-150 keV; 1.4-1090 keV in the source rest frame) at a
very early source-frame time (22 s). GRB050904 was a long, multi-peaked, bright
GRB with strong variability during its entire evolution. The light curve
observed by the XRT is characterized by the presence of a long flaring activity
lasting up to 1-2 hours after the burst onset in the burst rest frame, with no
evidence of a smooth power-law decay following the prompt emission as seen in
other GRBs. However, the BAT tail extrapolated to the XRT band joins the XRT
early light curve and the overall behavior resembles that of a very long GRB
prompt. The spectral energy distribution softens with time, with the photon
index decreasing from -1.2 during the BAT observation to -1.9 at the end of the
XRT observation. The dips of the late X-ray flares may be consistent with an
underlying X-ray emission arising from the forward shock and with the
properties of the optical afterglow reported by Tagliaferri et al. (2005b). We
interpret the BAT and XRT data as a single continuous observation of the prompt
emission from a very long GRB. The peculiarities observed in GRB050904 could be
due to its origin within one of the first star-forming regions in the Universe;
very low metallicities of the progenitor at these epochs may provide an
explanation.Comment: 9 pages, 2 table, 6 figures, accepted for publication on A&
Dark energy survey year 1 results: calibration of redMaGiC redshift distributions in DES and SDSS from cross-correlations
FINEP - FINANCIADORA DE ESTUDOS E PROJETOSFAPERJ - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DO RIO DE JANEIROCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOMCTIC - MINISTÉRIO DA CIÊNCIA, TECNOLOGIA, INOVAÇÕES E COMUNICAÇÕESWe present calibrations of the redshift distributions of redMaGiC galaxies in the Dark Energy Survey Year 1 (DES Y1) and Sloan Digital Sky Survey (SDSS) DR8 data. These results determine the priors of the redshift distribution of redMaGiC galaxies, which were used for galaxy clustering measurements and as lenses for galaxy-galaxy lensing measurements in DES Y1 cosmological analyses. We empirically determine the bias in redMaGiC photometric redshift estimates using angular cross-correlations with Baryon Oscillation Spectroscopic Survey (BOSS) galaxies. For DES, we calibrate a single-parameter redshift bias in three photometric redshift bins: z is an element of [0.15, 0.3], [0.3,0.45], and [0.45,0.6]. Our best-fit results in each bin give photometric redshift biases of vertical bar Delta z vertical bar < 0.01. To further test the redMaGiC algorithm, we apply our calibration procedure to SDSS redMaGiC galaxies, where the statistical precision of the cross-correlation measurement is much higher due to a greater overlap with BOSS galaxies. For SDSS, we also find best-fit results of vertical bar Delta z vertical bar < 0.01. We compare our results to other analyses of redMaGiC photometric redshifts.481224272443FINEP - FINANCIADORA DE ESTUDOS E PROJETOSFAPERJ - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DO RIO DE JANEIROCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOMCTIC - MINISTÉRIO DA CIÊNCIA, TECNOLOGIA, INOVAÇÕES E COMUNICAÇÕESFINEP - FINANCIADORA DE ESTUDOS E PROJETOSFAPERJ - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DO RIO DE JANEIROCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOMCTIC - MINISTÉRIO DA CIÊNCIA, TECNOLOGIA, INOVAÇÕES E COMUNICAÇÕESSem informaçãoSem informaçãoSem informaçãoSem informaçãoAgências de fomento estrangeiras apoiaram essa pesquisa, mais informações acesse artig
Modelling of the effect of ELMs on fuel retention at the bulk W divertor of JET
Effect of ELMs on fuel retention at the bulk W target of JET ITER-Like Wall was studied with multi-scale calculations. Plasma input parameters were taken from ELMy H-mode plasma experiment. The energetic intra-ELM fuel particles get implanted and create near-surface defects up to depths of few tens of nm, which act as the main fuel trapping sites during ELMs. Clustering of implantation-induced vacancies were found to take place. The incoming flux of inter-ELM plasma particles increases the different filling levels of trapped fuel in defects. The temperature increase of the W target during the pulse increases the fuel detrapping rate. The inter-ELM fuel particle flux refills the partially emptied trapping sites and fills new sites. This leads to a competing effect on the retention and release rates of the implanted particles. At high temperatures the main retention appeared in larger vacancy clusters due to increased clustering rate
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