MiniBooNE Neutrino Oscillation data - : Mostly consistent with the standard model
April 12th, 2007
The MiniBooNE results are out (sort of). MiniBooNE is designed to probe the Neutrino oscillations. MiniBioonE is a short for Booster Neutrino Experiment; “Booster” refers to a Fermilab booster ring that accelerates protons, and “mini” because a second, larger stage is planned.
It is a fascinating experiment. It attempts to count the number of times muon neutrino turns in to an electron neutrino. The experiment slams a beam of protons into a piece of beryllium, and the cascade of particles from the collision travel about 1,650 feet to a detection chamber, which has a 40 feet in diameter tank that contains 250,000 gallons of mineral oil and is surrounded by the detectors.
Most of the neutrinos just fly through, but occasionally a muon neutrino crashes in to a carbon atom in the oil and creates an electron neutrino which is detected by 1,280 light detectors mounted on the inside of the tank.
The experiment started in 1997 and the results were announced today. For most of the neutrino energy range they looked at, they did not see any more electron neutrinos than would be predicted by the Standard Model. But at the lower energies, the scientists did see more electron neutrinos than predicted: 369, rather than the predicted 273! Also see an excellent blog by Heather Ray.
“I was sort of expecting a clear excess or no excess,” he said. “In a sense, we got both.”
To me, the excess just looks spurious! We have waited 10 years for this experiment to complete. The data was “unblinded” and analyzed just a couple of weeks ago. I can wait for a little longer to figure out what that excess is. This is even worse than the Higgs bump. The Bump, I can understand but when the excess tracks the increase in the background levels at the same energies, extra caution is needed.
Mind you, I am not complaining; these are complex experiments and unravelling complexity takes time!
Filed under: check back in two to five years!
Here are some beautiful pictures of the detectors, if you haven’t seen them.
And my favorite!
Looks like some bugs from outer space invading the detector!
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