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Posts Tagged ‘neutrino

“There is a size at which dignity begins”*…



The spectrometer for the KATRIN experiment, as it works its way through the German town of Eggenstein-Leopoldshafen in 2006 en route to the nearby Karlsruhe Institute of Technology


Isaac Asimov dubbed neutrinos “ghost particles.” John Updike immortalized them in verse. They’ve been the subject of several Nobel Prize citations, because these weird tiny particles just keep surprising physicists. And now we have a much better idea of the upper limit of what their rest mass could be, thanks to the first results from the Karlsruhe Tritium Neutrino experiment (KATRIN) in Germany. Leaders from the experiment announced their results last week at a scientific conference in Japan and posted a preprint to the physics arXiv.

“Knowing the mass of the neutrino will allow scientists to answer fundamental questions in cosmology, astrophysics, and particle physics, such as how the universe evolved or what physics exists beyond the Standard Model,” said Hamish Robertson, a KATRIN scientist and professor emeritus of physics at the University of Washington…

Physicists get small: “Weighing in: Physicists cut upper limit on neutrino’s mass in half.”

* Thomas Hardy, “Two on a Tower”


As we step onto the scales, we might spare a thought for Max Karl Ernst Ludwig Planck; he died on this date in 1947.  A theoretical physicist, he is best remembered as the originator of quantum theory.  It was his discovery of energy quanta that won him the Nobel Prize in Physics in 1918.

220px-Max_Planck_1933 source


Written by LW

October 4, 2019 at 1:01 am

Next to nothing…

Neutinos are so small and so nearly without mass that 50 trillion of them pass unimpeded through a person’s body every second.  Ironically, this nearly nonexistent particle seems poised to start a revolution…

One of the two detectors in the MINOS neutrino experiment sits in the Soudan Underground Laboratory in Minnesota. A recent analysis of MINOS data hints that neutrinos and antineutrinos might not weigh the same-- a challenge to Einstein’s theory of special relativity.

Current theories of particle physics are based on two assumptions: All known forces arise from interactions with neighboring particles and they all obey Einstein’s special relativity theory, which holds that the speed of light and the laws of physics are always the same regardless of a particle’s speed or rotation. For that to hold true, particles and antiparticles—-including neutrinos and their antipartners — must have the same mass.

But new measurements from an experiment called MINOS (for Main Injector Neutrino Oscillation Search) seem to contradict that notion. The three known types of neutrinos —electron, muon and tau — act like chameleons, transforming from one type into another as they travel.

MINOS found that during a 735-kilometer journey from Fermilab to the Soudan Underground Laboratory in Minnesota, about 37 percent of muon antineutrinos disappeared — presumably morphing into one of the other neutrino types — compared with just 19 percent of muon neutrinos, reports MINOS spokesman Robert Plunkett of Fermilab.

That difference in transformation rates suggests a difference in mass between antineutrinos and neutrinos… “One thing is clear — if the masses are different for neutrinos and antineutrinos, then the most sacred symmetry of quantum field theory, CPT (for charge, parity and time), is broken in the neutrino sector,” says Tom Weiler of Vanderbilt University in Nashville.

Read the full story in Science News.

As we wax nostalgic for symmetry, we might send a “Alles Gute zum Geburtstag” to the remarkable Gottfried Wilhelm Leibniz, the philosopher, mathematician, and political adviser, who was important both as a metaphysician and as a logician, but who is probably best remembered for his independent invention of the calculus; he was born on this date in 1646.  Leibniz independently discovered and developed differential and integral calculus, which he published in 1684;  but he became involved in a bitter priority dispute with Isaac Newton, whose ideas on the calculus were developed earlier (1665), but published later (1687).


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