Scientists developed a new tabletop particle detector that can identify single electrons in radioactive gas.
As this gas decays, it emits electrons that can be trapped by a magnetic bottle, and a radio antenna can pick off signals given off by these captive electrons, MIT reported. This technique can allow researchers to map the electrons' precise activity over several milliseconds.
The novel method allowed a research team to record the activity of 100,000 individual electrons in krypton gas. Most of these observed electrons behaved in a characteristic pattern; as the gas decays it emits vibrating electrons that slowly calm down before spiking again in frequency when hit with more gas atoms. As the electrons "ping-pong" against atoms in the detector, their energy progresses in a step-like pattern.
"We can literally image the frequency of the electron, and we see this electron suddenly pop into our radio antenna," said Joe Formaggio, an associate professor of physics at MIT. "Over time, the frequency changes, and actually chirps up. So these electrons are chirping in radio waves."
The method could help scientists accomplish an even greater feat; measuring the mass of the elusive neutrino. These "ghostly" particles pass through the body in groups of billions every second, but are yet to be concretely detected. Scientists have set theoretical limits on a neutrino's mass, but are still finding difficulty gaining more insight into these particles.
"We have [the mass] cornered, but haven't measured it yet," Formaggio said. "The name of the game is to measure the energy of an electron -- that's your signature that tells you about the neutrino."
When a radioactive atom decays, it turns into an isotope of helium and releases an electron and a neutrino; the energy of all particles adds up to the total energy of the parent neutrino. This means that measuring the energy of the electron can reveal the mass of the neutrino.
Researchers hope to measure electrons in the radioactive atom tritium using a massive spectrometer as part of an experiment named KATRIN (Karlsruhe Tritium Neutrino Experiment).
"In KATRIN, the electrons are detected in a silicon detector, which means the electrons smash into the crystal, and a lot of random things happen, essentially destroying the electrons," said Daniel Furse, a graduate student in physics, and a co-author on the paper. "We still want to measure the energy of electrons, but we do it in a nondestructive way."
This new setup gives the researchers a valuable advantage because of its tiny tabletop size' in contrast, KATRIN's spectrometer could barely fit through a city street. Based on the precision of measurement of the device demonstrated with krypton gas, the same could be achieved with tritium within the next two years, potentially resulting in an accurate measurement of the mass of a neutrino.
The findings were published in a recent edition of the journal Physical Review Letters.
