Neutron emission
Neutron emission is a rarely occurring form of radioactivity in which an atomic nucleus radioactively decays by emitting a neutron . An example of this is 5 He, an isotope of helium :
5 He → 4 He + 1 n
Only isotopes with a considerable excess of neutrons decay through neutron emission. Most of these are generated artificially, for example by spallation or induced nuclear fission . Naturally occurring radioactive isotopes mostly decay through alpha , beta or gamma decay . Only in the case of spontaneous fission or in the r-process are neutron emitters naturally generated, in natural reactors also by induced fission. The emission is mostly based on an excited state of the nucleus, which was populated by a previous beta decay.
The half-life of neutron emitters is generally very short and is rarely more than a few seconds. However, with their delayed release of neutrons , these nuclei play a central role in the controllability of nuclear reactors .
Double neutron emission
The occurrence of a two-neutron decay is even rarer. Not only one but two neutrons are emitted at the same time. Such a decay was first observed in 2012 in the National Superconducting Cyclotron Laboratory (NSCL) on an artificial isotope of beryllium :
16 Be → 14 Be + 2 n
See also
Individual evidence
- ↑ Focus: Nuclei Emit Paired-Up Neutrons . In: American Physical Society - Physics Journal, March 9, 2012. Retrieved August 23, 2013