Durham University: New neutron lifetime measurement “key” to understanding early universe

A research team has refined its measurements of a particle that could be “key” to understanding the early universe.

The team was led by Dr Jack Wilson from the Johns Hopkins Applied Physics Laboratory (APL) and included Dr Jacob Kegerreis from our Department of Physics. They became the first to show how to use spaced-based measurements to determine the lifespan of a neutron.

The importance of studying neutrons

Knowing the lifetime of neutrons is key to understanding the formation of elements after the Big Bang 13.8 billion years ago, and could influence the standard model of physics that governs our understanding of the formation of the universe.

Neutron lifetime is the easiest and most direct way of measuring the weak force, one of four fundamental forces in nature.

The weak force governs certain types of radioactive decay, including the natural breakdown of lone neutrons into a proton, electron and anti-neutrino. It even kicks off the nuclear fusion reaction that powers the Sun and other stars.

Development in research

Last year the team used data that NASA’s MESSENGER spacecraft collected as it flew over Venus and Mercury, which showed a neutron lifetime of about 13 minutes.

Building on that research, the team this time used data from NASA’s 1998 Lunar Prospector mission to improve their calculations of how long neutrons can survive. They estimate that neutrons are able to survive for roughly 14 minutes 47 seconds, with an uncertainty of 15 seconds.

Their method relies on neutrons released into space by cosmic rays colliding with atoms on a planet’s surface or in its atmosphere. The further the neutrons travel from the planet’s surface, the more time passes and the more neutrons decay.

Looking to the future

The success of the Lunar Prospector data, highlights that the Moon is a viable and logical destination for a mission to study neutron lifetime.

The team hopes a planned mission where measuring the neutron lifetime is a focus from the outset, amongst other things, would provide an even more accurate timespan of a neutron’s survival.

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