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Ultimo Urlo - Inviato da: carlo - Mercoledì, 19 Febbraio 2014 07:44
accastampato n. 12 è online!
 
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Ultime News
Tesi, Dottorati, Summer School, Stage e
Borsa di studio Postlaurea
 

Bando Borsa Post Laurea INFN per sviluppo rivelatori a neutroni ai Laboratori Nazionali di Frascati ...

Da rfaccini, Mercoledì, 02 Aprile 2014 21:55 Commenti(1), Leggi tutto
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FameLab dal CERN
 

diretta streaming ...

Da carlo, Giovedì, 27 Marzo 2014 16:02 Commenti(0), Leggi tutto
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“How confident can we be that the signal detected by BICEP2 is, in fact, the imprint of primordial gravitational waves on the cosmic microwave background that cosmologists were hoping for?”
 

BICEP2: Is the Signal Cosmological?
I have a short gap in my schedule today so I thought I would use it to post a short note about the BICEP2 results announced to great excitement on Monday

There has been a great deal of coverage in the popular media about a “Spectacular Cosmic Discovery” and this is mirrored by excitement at a more technical level about the theoretical implications of the BICEP2 results. Having taken a bit of time out last night to go through the discovery paper, I think I should say that I think all this excitement is very premature. In that respect I agree with the result of my straw poll.

First of all let me make it clear that the BICEP2 experiment is absolutely superb. It was designed and built by top-class scientists and has clearly functioned brilliantly to improve its sensitivity so much that it has gone so far ahead of so many rivals:

Read all... ...

Da carlo, Giovedì, 20 Marzo 2014 10:35 Commenti(0), Leggi tutto
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il preprint di BICEP2 I: Detection Of B-mode Polarization at Degree Angular Scales
 

We report results from the BICEP2 experiment, a Cosmic Microwave Background (CMB) polarimeter specifically designed to search for the signal of inflationary gravitational waves in the B-mode power spectrum around l=80. The telescope comprised a 26 cm aperture all-cold refracting optical system equipped with a focal plane of 512 antenna coupled transition edge sensor (TES) 150 GHz bolometers each with temperature sensitivity of approx. 300 uk.sqrt(s). BICEP2 observed from the South Pole for three seasons from 2010 to 2012. A low-foreground region of sky with an effective area of 380 square degrees was observed to a depth of 87 nK-degrees in Stokes Q and U. In this paper we describe the observations, data reduction, maps, simulations and results. We find an excess of B-mode power over the base lensed-LCDM expectation in the range 305σ. Through jackknife tests and simulations based on detailed calibration measurements we show that systematic contamination is much smaller than the observed excess. We also estimate potential foreground signals and find that available models predict these to be considerably smaller than the observed signal. These foreground models possess no significant cross-correlation with our maps. Additionally, cross-correlating BICEP2 against 100 GHz maps from the BICEP1 experiment, the excess signal is confirmed with 3σ significance and its spectral index is found to be consistent with that of the CMB, disfavoring synchrotron or dust at 2.3σ and 2.2σ, respectively. The observed B-mode power spectrum is well-fit by a lensed-LCDM + tensor theoretical model with tensor/scalar ratio r=0.20+0.07−0.05, with r=0 disfa ...

Da carlo, Mercoledì, 19 Marzo 2014 09:25 Commenti(0), Leggi tutto
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We’ve found the smoking gun evidence for inflation and we’ve also produced the first image of gravitational waves across the sky
 

Physicists have found a long-predicted twist in light from the Big Bang that represents the first image of ripples in the universe called gravitational waves, researchers announced today. The finding is direct proof of the theory of inflation, the idea that the universe expanded extremely quickly in the first fraction of a second after it was born. What’s more, the signal is coming through much more strongly than expected, ruling out a large class of inflation models and potentially pointing the way toward new theories of physics, experts say.

Read all ...

Da carlo, Lunedì, 17 Marzo 2014 16:59 Commenti(0), Leggi tutto
 
 

Accatagliato è una associazione di volontariato fra studenti, dottorandi e ricercatori di Fisica,
principalmente costituita da studenti delle Università di Roma "Sapienza e "Roma Tre"

L'Associazione si propone di promuovere e sviluppare la cultura, sostenendo processi di conoscenza e di socializzazione delle informazioni di carattere culturale e scientifico,
anche al fine del superamento dei problemi che riguardano la società e volte a favorire un progresso collettivo e un miglioramento della qualità della vita,
con particolare riguardo ai giovani e, a tale scopo, collaborando anche con gli istituti scolastici di ogni ordine e grado

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