Neutron: Forskelle mellem versioner
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Neutronen er en [[baryon]]. Den består af tre [[kvark (fysik)|kvarker]], en up-kvark og to down-kvarker. Neutronen vekselvirker som andre [[hadron]]er (partikler som er opbygget af kvarker) ved den [[stærk kernekraft|stærke kernekraft]]. Af neutronens sammensætning følger at den har spin ½, og hermed er den en [[fermion]].
En fri neutron er ustabil. Den henfalder [[radioaktivitet|radioaktivt]] til en proton og en [[elektron]]
The exact value of the mean lifetime is still uncertain, due to conflicting results from experiments.
The Particle Data Group reports values up to six seconds apart (more than four standard deviations), commenting that
"our 2006, 2008, and 2010 Reviews stayed with 885.7±0.8 s; but we noted that in light of SEREBROV 05 our value should be regarded as suspect until further experiments clarified matters. Since our 2010 Review, PICHLMAIER 10 has obtained a mean life of 880.7±1.8 s, closer to the value of SEREBROV 05 than to our average. And SEREBROV 10B[...] claims their values should be lowered by about 6 s, which would bring them into line with
the two lower values. However, those reevaluations have not received an enthusiastic response from the experimenters in question; and in any case the Particle Data Group would have to await published changes (by those experimenters) of published values.
At this point, we can think of nothing better to do than to average the seven best but discordant measurements, getting 881.5±1.5s. Note that the error includes a scale factor of 2.7. This is a jump of 4.2 old
(and 2.8 new) standard deviations. This state of affairs is a particularly unhappy one, because the value is so important. We again call upon the experimenters to clear this up."
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[[Antipartikel|Antipartiklen]] til neutronen er '''antineutronen''' der består af antikvarker (én anti-up og to anti-down), og som henfalder til en [[antiproton]] og en positron (samt en neutrino).
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