Device can detect single electrons

Researchers hope that the detector will eventually be able to aid in the calculation of the mass of a neutrino.
By Andrew McDonald | Apr 21, 2015
According to a Massachusetts Institute of Technology statement, a team of researchers has developed an apparatus capable of detecting individual elections. The device uses radioactive krypton gas that emits electrons as it decays. These electrons are trapped in a magnetic bottle, allowing a radio antenna to detect the extremely slight signals given off by the electrons. The device allowed the scientists to study the behavior of more than 100,000 electrons over several milliseconds.

The experiment, dubbed Project 8, builds upon cyclotron radiation. In this process, charged particles give off radio waves in the presence of a magnetic field. Cyclotron radiation from electrons is at around the same frequency, 26 gigahertz, as military radio transmissions. The research team decided to use this phenomenon to obtain hitherto unprecedented accuracy when measuring the energy of electrons.

After a choppy five-year development period, the device was able to detect single electrons within its first hundred milliseconds of operation. In the next stage, the researchers want to experiment with tritium and attempt to determine the mass of neutrinos.

Neutrinos are extremely difficult to measure; despite their profusion in the Universe, they do not interact with normal matter even as they pass through it. The mass of a neutrino has been theoretically constrained, but never measured. Tritium is a natural candidate for an experiment designed to measure neutrinos, as the electrons produced by its decay are easy to detect. As an atom of tritium decays into an isotope of helium, it releases an electron and a neutrino. The total energy of these emitted particles equals the energy of the original neutron. Knowing this total energy and the energy of the electron reveals the energy of the neutrino, from which the neutrino's mass can be derived.

The new findings have been published in the journal Physical Review Letters.


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