نتایج جستجو برای: neutron decay
تعداد نتایج: 117888 فیلتر نتایج به سال:
Total absorption spectroscopy is used to investigate the β-decay intensity to states above the neutron separation energy followed by γ-ray emission in (87,88)Br and (94)Rb. Accurate results are obtained thanks to a careful control of systematic errors. An unexpectedly large γ intensity is observed in all three cases extending well beyond the excitation energy region where neutron penetration is...
Measurement of the Neutron Lifetime Using a Gravitational Trap and a Low-Temperature Fomblin Coating
We present a new value for the neutron lifetime of 878.5 ± 0.7stat. ± 0.3syst. This result differs from the world average value by 6.5 standard deviations and by 5.6 standard deviations from the previous most precise result. However, this new value for the neutron lifetime together with a β-asymmetry in neutron decay, A 0, of -0.1189(7) is in a good agreement with the Standard Model.
We review and discuss the time-reversal-odd R and D correlations in neutron and nuclear beta decay.
1 Energy release in alpha-decay 2 Consider a nucleus which is stable against decay by proton or neutron emission { the least bound nucleon still has (say) several MeV of binding energy. This nucleus may nevertheless still be able to decay by using the fact that if it can emit an alpha-particle (2He), it can use the binding energy of the alpha to supply the energy needed for the escape. That is,...
It was first suggested by Heisenberg that the forces between a proton and a neutron are connected with an exchange of charge between the two heavy particles. This exchange nature of the neutron-proton forces is now generally accepted. It would follow from this assumption that in suitable circumstances a proton (neutron) could emit a positively (negatively) charged particle transforming itself i...
The nearby isolated neutron stars are a group of seven relatively slowly rotating neutron stars that show thermal X-ray spectra, most with broad absorption features. They are interesting both because they may allow one to determine fundamental neutron-star properties by modeling their spectra, and because they appear to be a large fraction of the overall neutron-star population. Here, we descri...
Accurate partial gamma-ray production cross sections were determined for the prompt and radioactive product decay gamma rays following cold neutron capture in Tc. They can be used for non-destructive assay of technetium by prompt gamma activation analysis (PGAA) and neutron activation analysis (NAA), offering orders of magnitude higher analytical sensitivities than passive gamma-ray counting. A...
A precise measurement of the neutron decay β asymmetry A₀ has been carried out using polarized ultracold neutrons from the pulsed spallation ultracold neutron source at the Los Alamos Neutron Science Center. Combining data obtained in 2008 and 2009, we report A₀ = -0.119 66±0.000 89{-0.001 40}{+0.001 23}, from which we determine the ratio of the axial-vector to vector weak coupling of the nucle...
A delicate interplay between the anomalous magnetic moments of the proton and neutron makes, in magnetic fields B ≥ 2 × 10 T, the neutron stable and for fields B ≥ 5 × 10 T the proton becomes unstable to a decay into a neutron via β emission. Limits on the field strengths for which these arguments hold are presented and are related to questions of vacuum stability in the presence of such fields...
A search for Supernova Relic Neutrinos ν̄e’s is first conducted via inverse-beta-decay by tagging neutron capture on hydrogen at Super-Kamiokande-IV. The neutron tagging efficiency is determined to be (17.74 ± 0.04stat. ± 1.05sys.)%, while the corresponding accidental background probability is (1.06 ± 0.01stat. ± 0.18sys.)%. Using 960 days of data, we obtain 13 inverse-beta-decay candidates in t...
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