* Astronomy

Blobrana · L

RE: OPERA neutrino experiment

Blobrana · L

ICARUS experiment at Gran Sasso laboratory reports new measurement of neutrino time of flight consistent with the speed of light

The ICARUS experiment at the Italian Gran Sasso laboratory has today reported a new measurement of the time of flight of neutrinos from CERN to Gran Sasso. The ICARUS measurement, using last year's short pulsed beam from CERN, indicates that the neutrinos do not exceed the speed of light on their journey between the two laboratories. This is at odds with the initial measurement reported by OPERA last September.
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Blobrana · L

Faster-than-light neutrinos could be down to bad wiring

What might have been the biggest physics story of the past century may instead be down to a faulty connection.
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Blobrana · L

OPERA experiment reports anomaly in flight time of neutrinos from CERN to Gran Sasso

The OPERA collaboration has informed its funding agencies and host laboratories that it has identified two possible effects that could have an influence on its neutrino timing measurement. These both require further tests with a short pulsed beam. If confirmed, one would increase the size of the measured effect, the other would diminish it. The first possible effect concerns an oscillator used to provide the time stamps for GPS synchronizations. It could have led to an overestimate of the neutrino's time of flight. The second concerns the optical fibre connector that brings the external GPS signal to the OPERA master clock, which may not have been functioning correctly when the measurements were taken. If this is the case, it could have led to an underestimate of the time of flight of the neutrinos. The potential extent of these two effects is being studied by the OPERA collaboration. New measurements with short pulsed beams are scheduled for May.
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Blobrana · L

The faster-than-light neutrinos seen by the OPERA particle physics experiment last year may have just been explained. By a loose cable.
Today, Science is reporting that a fibre optic cable connecting a GPS receiver and an electronic card in a computer was loose.
After tightening the connection and then measuring the time it takes data to travel the length of the fibre, researchers found that the data arrive 60 nanoseconds earlier than assumed
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Blobrana · L

Pions don't want to decay into faster-than-light neutrinos

When an international collaboration of physicists came up with a result that punched a hole in Einstein's theory of special relativity and couldn't find any mistakes in their work, they asked the world to take a second look at their experiment.
Responding to the call was Ramanath Cowsik, PhD, professor of physics in Arts & Sciences and director of the McDonnell Centre for the Space Sciences at Washington University in St. Louis.
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Blobrana · L

Title: Tachyonic Majorana neutrinos or neutrino spin-to-orbital angular momentum conversion in OPERA
Authors: M. Laveder, F. Tamburini, ((1) Department of Physics and Astronomy, University of Padova, via Marzolo 8, Padova, Italy and INFN - Sezione di Padova - (2) Department of Physics and Astronomy, University of Padova, via Marzolo 8, Padova, Italy and CIVEN, Venezia)

The new data release of OPERA - CNGS experiment, obtained with a shorter spill of protons, confirms the tachyionic behaviour expected from the phenomenological model of a Majorana neutrino with a fictitious imaginary mass term acquired during the propagation in the Earth's crust, recently presented by us. We performed numerical simulations of neutrino event detections to compare the properties of these Majorana tachyons with the new OPERA results, finding a good agreement. The possibility of spin-to orbital angular momentum conversion that is expected to give a negative squared mass in a medium, is also briefly discussed.

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Blobrana · L

New results fail to rule out 'faster than light' neutrinos

New results (18 November 2011) from the OPERA collaboration based at the Gran Sasso Laboratory in Italy support earlier experiments that suggested that neutrinos can travel faster than the speed of light.
The initial results released on 23 September caused an international sensation because they could dismiss one of the key assumptions that underpins modern physics. Since then scientists around the world have been scrutinising every aspect of those experiments looking for clues that might explain the perplexing results.
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Blobrana · L

OPERA experiment reports anomaly in flight time of neutrinos from CERN to Gran Sasso

Following the OPERA collaboration's presentation at CERN on 23 September, inviting scrutiny of their neutrino time-of-flight measurement from the broader particle physics community, the collaboration has rechecked many aspects of its analysis and taken into account valuable suggestions from a wide range of sources. One key test was to repeat the measurement with very short beam pulses from CERN. This allowed the extraction time of the protons, that ultimately lead to the neutrino beam, to be measured more precisely.
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Blobrana · L

Title: Measurement of the neutrino velocity with the OPERA detector in the CNGS beam
Authors: The OPERA Collaboraton: T. Adam, N. Agafonova, A. Aleksandrov, O. Altinok, P. Alvarez Sanchez, A. Anokhina, S. Aoki, A. Ariga, T. Ariga, D. Autiero, A. Badertscher, A. Ben Dhahbi, A. Bertolin, C. Bozza, T. Brugière, R. Brugnera, F. Brunet, G. Brunetti, S. Buontempo, B. Carlus, F. Cavanna, A. Cazes, L. Chaussard, M. Chernyavsky, V. Chiarella, A. Chukanov, G. Colosimo, M. Crespi, N. D'Ambrosio, G. De Lellis, M. De Serio, Y. Déclais, P. del Amo Sanchez, F. Di Capua, A. Di Crescenzo, D. Di Ferdinando, N. Di Marco, S. Dmitrievsky, M. Dracos, D. Duchesneau, S. Dusini, J. Ebert, I. Efthymiopoulos, O. Egorov, A. Ereditato, L. S. Esposito, J. Favier, T. Ferber, R. A. Fini, T. Fukuda, A. Garfagnini, G. Giacomelli, M. Giorgini, M. Giovannozzi, C. Girerd, J. Goldberg, C. Göllnitz, et al. (122 additional authors not shown)
(Version v2)

The OPERA neutrino experiment at the underground Gran Sasso Laboratory has measured the velocity of neutrinos from the CERN CNGS beam over a baseline of about 730 km with much higher accuracy than previous studies conducted with accelerator neutrinos. The measurement is based on high-statistics data taken by OPERA in the years 2009, 2010 and 2011. Dedicated upgrades of the CNGS timing system and of the OPERA detector, as well as a high precision geodesy campaign for the measurement of the neutrino baseline, allowed reaching comparable systematic and statistical accuracies. An early arrival time of CNGS muon neutrinos with respect to the one computed assuming the speed of light in vacuum of (57.8 ± 7.8 (stat.)+8.3-5.9 (sys.)) ns was measured. This anomaly corresponds to a relative difference of the muon neutrino velocity with respect to the speed of light (v-c)/c = (2.37 ± 0.32 (stat.) (sys.)) x 10-5. The above result, obtained by comparing the time distributions of neutrino interactions and of protons hitting the CNGS target in 10.5 {\mu}s long extractions, was confirmed by a test performed using a beam with a short-bunch time-structure allowing to measure the neutrino time of flight at the single interaction level.

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