CrazyNeutrino said:
Physicists detect radio waves from a single electron
Physicists have long known that charged particles like electrons will spiral in a magnetic field and give off radiation. But nobody had ever detected the radio waves emanating from a single whirling electron—until now. The striking new technique researchers used to do it might someday help particle physicists answer a question that has vexed them for decades: How much does a ghostly particle called the neutrino weigh?
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More from link.
> This effect has been understood for a century. It’s used to generate x-ray beams by sending electrons racing around circular particle accelerators known as synchrotrons. Such radiation also emanates from swirling particles in interstellar space. Now, 27 physicists with Project 8, an experiment based at the University of Washington, Seattle, have detected radiation from a single electron. “I thought surely somebody must have done this,” says Brent VanDevender, a nuclear physicist and team member from Pacific Northwest National Laboratory in Richland, Washington. “I looked and looked and looked in the literature and couldn’t find anything.”
I couldn’t have put it better myself. Yes, synchrotron radiation has been understood for a century and does emanate from particles in space swirling around magnetic fields.
> The Project 8 team hopes to use the technique to measure the mass of the still-mysterious particles known as neutrinos, VanDevender says. They plan to study the tritium nucleus, which contains one proton and two neutrons. It undergoes a process called beta decay, in which one neutron turns into a proton while spitting out a neutrino and an electron. The nearly undetectable neutrino and the electron will share the energy released in the decay, with the split varying randomly from one decay to the next. By measuring the maximum energy of the electrons, researchers can deduce the minimum energy of the neutrinos, and hence the neutrino’s mass.
The mass of the electron neutrino is known to much worse percentage accuracy than the mass of the muon neutrino and tau neutrino. The link says it’s only known to be between 50 and 230 meV.