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For the free neutron, the decay energy for this process (based on the rest masses of the neutron, proton and electron) is 0.782 343 MeV. That is the difference between the rest mass of the neutron and the sum of the rest masses of the products. That difference has to be carried away as kinetic energy.
Neutron radiation is a form of ionizing radiation that presents as free neutrons. Typical phenomena are nuclear fission or nuclear fusion causing the release of free neutrons, which then react with nuclei of other atoms to form new nuclides —which, in turn, may trigger further neutron radiation.
A fast neutron is a free neutron with a kinetic energy level close to 1 MeV (1.6 × 10 −13 J), hence a speed of ~ 14 000 km/s (~ 5% of the speed of light). They are named fission energy or fast neutrons to distinguish them from lower-energy thermal neutrons, and high-energy neutrons produced in cosmic showers or accelerators.
At freeze out, the neutron–proton ratio was about 1/6. However, free neutrons are unstable with a mean life of 880 sec; some neutrons decayed in the next few minutes before fusing into any nucleus, so the ratio of total neutrons to protons after nucleosynthesis ends is about 1/7.
In neutron stars, the neutron drip is the transition point where nuclei become so neutron-rich that they can no longer hold additional neutrons, leading to a sea of free neutrons being formed. The sea of neutrons formed after neutron drip provides additional pressure support, which helps maintain the star's structural integrity and prevents ...
Astronomers have found evidence that a neutron star exists at the centre of the only exploding star – supernova – visible to the naked eye in the last 400 years, solving a 30-year-old mystery ...
Free neutrons—those not inside an atomic nucleus—are already known to decay into protons (and an electron and an antineutrino) in a process called beta decay. Free neutrons have a half-life of 10 minutes (610.2 ± 0.8 s) [17] due to the weak interaction. Neutrons bound inside a nucleus have an immensely longer half-life – apparently as ...
The cosmic collision could be the first example of a black hole colliding with a neutron star — possibly offering new insights into the expansion of the universe.