Physicists have moved tantalizingly closer to measuring the mass of the vital but elusive neutrino by building a tabletop particle detector that can isolate, track and record single electrons.
That physicists have managed to build a small, tabletop particle detector is a small miracle in itself when one considers the massive size of today's particle detectors such as the 200 ton KATRIN (Karlsruhe Tritium Neutrino Experiment) in Germany and the huge Super-Kamiokande neutrino detector under Mount Kamioka near the city of Hida, Gifu Prefecture in Japan.
Physicists from the Massachusetts Institute of Technology, Pacific Northwest National Lab, the University of Washington and the University of California at Santa Barbara spent five years working on their tabletop particle detector that can pick out single electrons in radioactive gas.
While being able to spot an electron with such a small detector is major step forward, it also takes the team further down the road of being able to measure the mass of a neutrino, one of the most mysterious elementary particles in the Universe.
Neutrinos are believed to be the reason why matter and not anti-matter prevails in the Universe, meaning that without the neutrino to tip the balance in favor of matter, the Universe as we know it wouldn't exist.
Neutrinos are also called "ghost particles" because they've almost no mass and no electric charge, making them almost nothing at all.
It's because of this that studying neutrinos is difficult. They're exceedingly hard to detect since they interact so weakly with standard matter, simply passing through it instead. Neutrinos are elementary particles throughout the Universe formed by the Big Bang.
One of the most practical ways to detect the presence of neutrinos is to measure the energy of an electron.
"We have (the mass) cornered, but haven't measured it yet," said Joe Formaggio, an associate professor of physics at MIT.
"The name of the game is to measure the energy of an electron -- that's your signature that tells you about the neutrino".
Even more amazing is that this table top device might actually achieve a goal that has eluded scientists since the neutrino was first postulated by Swiss theoretical physicist Wolfgang Pauli in 1930: measuring the mass of the neutrino.
The MIT detector utilizes magnets to trap electrons given off by decay of the radioactive gas holding them inside a magnetic bottle. Inside the bottle, electrons emit very weak signals that allow their activity to be recorded over several milliseconds.
That activity shows a characteristic pattern since the electrons vibrate at a particular baseline frequency that can spike whenever the electron collides with an atom of the radioactive gas.
An electron colliding with multiple atoms in the detector will display frequency jumps showing a step-like pattern, said Formaggio.
"We can literally image the frequency of the electron, and we see this electron suddenly pop into our radio antenna. Over time, the frequency changes, and actually chirps up. So these electrons are chirping in radio waves."
The work represents a significant step toward a long-sought but elusive goal of physics: determining the mass of a neutrino.
Scientists said neutrinos are an important building block for the blueprint of nature and are important to our understanding of the kind of processes that go on in the Sun.