New measurements from Fermilab's MINOS experiment suggest a difference in a key property of neutrinos and antineutrinos

MINOS announced today the world's most precise measurement to date of the parameters that govern antineutrino oscillations. The collaboration's antineutrino results are shown in red and the neutrino results in blue.

Batavia, Ill. - Scientists of the MINOS experiment at the Department of Energy's Fermi National Accelerator laboratory today (June 14) announced the world's most precise measurement to date of the parameters that govern antineutrino oscillations, the back-and-forth transformations of antineutrinos from one type to another. This result provides information about the difference in mass between different antineutrino types. The measurement showed an unexpected variance in the values for neutrinos and antineutrinos. This mass difference parameter, called Δm² ("delta m squared"), is smaller by approximately 40 percent for neutrinos than for antineutrinos.

However, there is a still a five percent probability that Δm² is actually the same for neutrinos and antineutrinos. With such a level of uncertainty, MINOS physicists need more data and analysis to know for certain if the variance is real.

Neutrinos and antineutrinos behave differently in many respects, but the MINOS results, presented today at the Neutrino 2010 conference in Athens, Greece, and in a seminar at Fermilab, are the first observation of a potential fundamental difference that established physical theory could not explain.

"Everything we know up to now about neutrinos would tell you that our measured mass difference parameters should be very similar for neutrinos and antineutrinos," said MINOS co-spokesperson Rob Plunkett. "If this result holds up, it would signal a fundamentally new property of the neutrino-antineutrino system. The implications of this difference for the physics of the universe would be profound."

Read more

Users' Meeting presents plans, proposals for future

The Main Injector accelerator at Fermilab produces the world's highest-intensity neutrino beam. Scientists plan to send the beam to the proposed DUSEL laboratory in South Dakota.

Fermilab has R&D underway for several future experiments across all frontiers of high-energy physics. The Fermilab Users' Meeting gave collaborators a chance to catch up on the planned and proposed experiments' progress.

"Fermilab is heavily invested in the Intensity Frontier, and we expect that investment to grow," said Andre de Gouvea of Northwestern University.

Fermilab plans to begin its second Extreme Beams lecture series in September, this time focusing on detector conceptual designs for precision measurements, rare decays and neutrino physics.

The Long Baseline Neutrino Experiment received CD-0 in January and is working toward CD-1 approval of the conceptual design and preliminary costs and schedule in 2011. Construction could start in 2014-15 and finish by 2020.

"The CD-0 has put Fermilab firmly in the driver's seat, and LBNE is heading up the on ramp for this project," said Robert Wilson of Colorado State University.

LBNE collaborators are working on a physics report for fall to guide the detector configuration and choices of the far detector scintillate. A CD-1 review of the conceptual design and preliminary costs and schedule could occur as early as December.

At the Energy Frontier, R&D on a proposed Muon Collider has been steadily making progress.

Read more

--Tona Kunz

Discrete space, general relativity, dark matter and the Casimir effect

From 13.7, an NPR blog on cosmos and culture, June 10, 2010

In an earlier blog, Marcelo discussed Dark Matter and stated that, with the exception of hopes of exotic particles called WIMPs, (Weakly Interacting massive particles) which have not been found, we have no idea what Dark Matter might be.

Fools rush in where physicists, no doubt wisely, do not tread. That said, I wish to propose concepts that may prove helpful with the issue of Dark Matter, relate to the hypothesis of discrete space on the Planck length scale that I discussed two blogs ago, seem to have potential relevance to General Relativity and perhaps quantum gravity, and appear to be testable now using the Casimir effect. I shall predict that the strength of the Casimir effect is weaker in a local gravitational field exactly in the proportion that General Relativity shows that space-time curves locally in a gravitational field.

Read more