====== Neutron decay ======

When part of an atomic nucleus, neutrons are extremely stable, but 'free' neutrons (i.e. those outside of a nucleus) decay into a proton, an electron and an electron-antineutrino in about 15 minutes.

Two different methods have been used to measure the neutron's 'lifespan'.

The 'bottle' method and the 'in-beam' method (described in the links below) give different results. The bottle method puts the decay time at 878.5 seconds ±1 second. With the beam method it's 887.7 seconds ±1.9 seconds.

Not only do the results differ by more than 9 seconds, but also the 'margin of error' figures //don't fit into the difference.// So either the measurements are wrong, or the error margin is wrong, or both.

Although the 9 seconds difference may seem minimal, it has very far-reaching implications for calculations regarding the [[content:physics:cosmology:big_bang|big bang]], where neutrons and protons are believed to have been forming within 20 minutes or so of the event, and when the (lighter) elements were created.

See: [[https://www.nature.com/news/neutron-death-mystery-has-physicists-stymied-1.15219|Neutron death mystery]] //Scientific American//, May 2014

Further tech info :

[[https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.111.222501|Improved Determination of the Neutron Lifetime]]// Phys. Rev. Lett.// 111, 222501

[[https://www.nist.gov/news-events/news/2014/02/toward-new-precision-measuring-neutron-lifetime|Toward New Precision in Measuring the Neutron Lifetime]] //NIST Center for Neutron Research//

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Also see [[content:physics:quantum_physics:neutron_cp_problem]]

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