Related papers: Precision measurement of the $\beta$-asymmetry in …
We report a measurement of the nuclear polarization of laser-cooled, optically-pumped $^{37}\mathrm{K}$ atoms which will allow us to precisely measure angular correlation parameters in the beta-decay of the same atoms. These results will be…
High precision measurements of isospin $T=1/2$ decays in the neutron and nuclei provide strong model-independent constraints on extensions to the standard model of particle physics. A measurement of the $\beta$-asymmetry in $^{19}$Ne decay…
The half-life of \tsups{37}K has been measured to be $1.23651(94)~\mathrm{s}$, a value nearly an order of magnitude more precise than the best previously reported. The $\beta^+$ decay of \tsups{37}K occurs mainly via a superallowed branch…
We present a detailed report of a measurement of the neutron $\beta$-asymmetry parameter $A_0$, the parity-violating angular correlation between the neutron spin and the decay electron momentum, performed with polarized ultracold neutrons…
A new measurement of the neutron $\beta$-decay asymmetry $A_0$ has been carried out by the UCNA collaboration using polarized ultracold neutrons (UCN) from the solid deuterium UCN source at the Los Alamos Neutron Science Center (LANSCE).…
We report the first measurement of angular correlation parameters in neutron $\beta$-decay using polarized ultracold neutrons (UCN). We utilize UCN with energies below about 200 neV, which we guide and store for $\sim 30$ s in a Cu decay…
We have measured the isospin mixing of the I$^\pi$= 1/2$^+$ E$_x$=2.599 MeV state in nearly-doubly-magic $^{47}$Ca with the isobaric analog 1/2$^+$ state of $^{47}$K. Using the TRIUMF atom trap for $\beta$ decay, we have measured a nonzero…
A new measurement of the neutrino asymmetry parameter B in neutron decay, the angular correlation between neutron spin and anti-neutrino momentum, is presented. The result, B=0.9802(50), agrees with the Standard Model expectation and…
The UCNA experiment was designed to measure the neutron $\beta$-asymmetry parameter $A_0$ using polarized ultracold neutrons (UCN). UCN produced via downscattering in solid deuterium were polarized via transport through a 7 T magnetic…
The Ultracold Neutron Asymmetry (UCNA) experiment was designed to measure the $\beta$-decay asymmetry parameter, $A_0$, for free neutron decay. In the experiment, polarized ultracold neutrons are transported into a decay trap, and their…
We report on a new measurement of neutron $\beta$-decay asymmetry. From the result \linebreak $A_0$ = -0.1189(7), we derive the ratio of the axial vector to the vector coupling constant $\lambda$ = ${\it g_A/g_V}$ = -1.2739(19). When…
Nuclear beta decays between (J^pi,T) = (0^+,1) analog states yield the best value for the Vud element of the Cabibbo-Kobayashi-Maskawa matrix. Current world data establish the corrected Ft values of 14 separate superallowed transitions to a…
Precision measurements at low energy search for physics beyond the Standard Model in a way complementary to searches for new particles at colliders. In the weak sector the most general $\beta$ decay Hamiltonian contains, besides vector and…
The neutron $\beta$-decay asymmetry parameter $A_0$ defines the correlation between the spin of the neutron and the momentum of the emitted electron, which determines $\lambda=\frac{g_{A}}{g_{V}}$, the ratio of the axial-vector to vector…
In the past, the mirror asymmetry parameter has been proposed as a probing mechanism for the presence of beyond the Standard Model second-class currents in nuclear beta decay transitions. However, this was hindered by large uncertainties in…
The proton asymmetry parameter C in neutron decay describes the correlation between neutron spin and proton momentum. In this Letter, the first measurement of this quantity is presented. The result C=-0.2377(26) agrees with the Standard…
In the present work, we report a comprehensive theoretical study of the $\log ft$ values for the allowed and forbidden $\beta^-$ decay transitions of $^{46}$K and $^{47}$K corresponding to recently available experimental data from the…
In recent years a number of correlation measurements in nuclear $\beta$ decay have been performed reaching a precision of the order of 1\% and below and it is expected that even higher precision will be reached in the near future. At these…
Superallowed $\beta$-decay studies provide some of the best constraints on the possibility of additional quark generations, as well as limits on exotic currents in the weak interaction. The three experimental quantities that are required…
We present a measurement of the charge asymmetry $\delta_L$ in the mode $K_L \to \pi^{\pm}e^{\mp}\nu$ based on 298 million analyzed decays. We measure a value of $\delta_L = (3322 \pm 58(stat) \pm 47(sys))\cdot 10^{-6}$, in good agreement…