Physicists Have Achieved The Smallest Measurement Yet of a Ghost Particle's Mass

The smallest measurement of the mass of a neutrino was made earlier this year.

The upper limit for the mass of the electron antineutrino is just 0.8 electronvolts, according to physicists.

In imperial terms, that's 1.6 10 36 kilograms in metric mass.

narrowing it down brings us closer to understanding these strange particles, the role they play in the Universe, and the impact they could have on our theories of physics.

At the KATRIN experiment in Germany, the achievement was made.

The second campaign of KATRIN reached sub-electronvolt sensitivity, according to the researchers.

"Combined with the first campaign, we set an improved upper limit of mν

Neutrinos are very strange. They are one of the most abundant particles in the Universe, similar to electrons, but without a charge and mass.

Billions of people are passing through your body right now, and they are interacting very rarely with normal matter.

They are called ghost particles because of this. It makes them hard to detect. There are some methods for detecting the effects of passing neutrinos, but they are indirect and not as effective as the neutrinos themselves.

Measuring the near-zero mass of these particles is a difficult task.

There will be a lot more we can learn about the Universe if we can measure this property. It is very difficult to do. It's not possible to just grab a tiny scale and call it quits.

The mass of a neutrino is probed by using the decay of tritium. A huge, sensitive spectrometer probes the results of the decay of tritium gas within the 70 meter chamber.

It is not possible to measure the ghosts. If you measure the energy of the electrons, you can derive the energy of the neutrino.

This is how the team was able to get the upper limit of 1 electronvolt.

The team used an increase in the number of tritium decays with methods to reduce the amount of other types of radioactive decay in order to refine that result.

"This laborious and intricate work was the only way to exclude a systematic bias of our result," said physicists Magnus Schlsser of the Karlsruhe Institute of Technology.

The analysis team accepted the challenge and was successful.

It's the first time that a measurement of a neutrino has fallen below the threshold. Scientists will be able to refine physical models of the Universe thanks to this result.

Efforts will be made to refine the measurement of the mass of the neutrino.

The researchers said that the neutrino mass will be measured until the end of the century.

To exhaust the full potential of this experiment, we will steadily increase the statistics of signal events and continuously develop and install upgrades.

Nature physics has published the results.

The first version of this article was published in February of 1992.