28 research outputs found
Resultados finales para el parĂĄmetro de asimetrĂa ? de neutrones A 0 del experimento UCNA
The UCNA experiment was designed to measure the neutron ?-asymmetry parameter A0 using polarized ultracold neutrons (UCN). UCN produced via downscattering in solid deuterium were polarized via transport through a 7 T magnetic field, and then directed to a 1 T solenoidal electron spectrometer, where the decay electrons were detected in electron detector packages located on the two ends of the spectrometer. A value for A0 was then extracted from the asymmetry in the numbers of counts in the two detector packages. We summarize all of the results from the UCNA experiment, obtained during run periods in 2007, 2008â2009, 2010, and 2011â2013, which ultimately culminated in a 0.67% precision result for A0
Weak Interaction Studies with 6He
The 6He nucleus is an ideal candidate to study the weak interaction. To this
end we have built a high-intensity source of 6He delivering ~10^10 atoms/s to
experiments. Taking full advantage of that available intensity we have
performed a high-precision measurement of the 6He half-life that directly
probes the axial part of the nuclear Hamiltonian. Currently, we are preparing a
measurement of the beta-neutrino angular correlation in 6He beta decay that
will allow to search for new physics beyond the Standard Model in the form of
tensor currents.Comment: 5 pages, 4 figures, proceedings for the Eleventh Conference on the
Intersections of Particle and Nuclear Physics (CIPANP 2012
First direct constraints on Fierz interference in free neutron decay
Precision measurements of free neutron -decay have been used to
precisely constrain our understanding of the weak interaction. However the
neutron Fierz interference term , which is particularly sensitive to
Beyond-Standard-Model tensor currents at the TeV scale, has thus far eluded
measurement. Here we report the first direct constraints on this term, finding
,
consistent with the Standard Model. The uncertainty is dominated by absolute
energy reconstruction and the linearity of the beta spectrometer energy
response
Weak Interaction Studies ith \u3csup\u3e6\u3c/sup\u3eHe
The 6He nucleus is an ideal candidate to study the weak interaction. To this end we have built a high-intensity source of 6He delivering âŒ1010 atoms/s to experiments. Taking full advantage of that available intensity we have performed a high-precision measurement of the 6He half-life that directly probes the axial part of the nuclear Hamiltonian. Currently, we are preparing a measurement of the beta-neutrino angular correlation in 6He beta decay that will allow to search for new physics beyond the Standard Model in the form of tensor currents. © 2013 AIP Publishing LLC
Final results for the neutron ÎČ-asymmetry parameter Aâ from the UCNA experiment
The UCNA experiment was designed to measure the neutron ÎČ-asymmetry parameter A0 using polarized ultracold neutrons (UCN). UCN produced via downscattering in solid deuterium were polarized via transport through a 7âT magnetic field, and then directed to a 1âT solenoidal electron spectrometer, where the decay electrons were detected in electron detector packages located on the two ends of the spectrometer. A value for A0 was then extracted from the asymmetry in the numbers of counts in the two detector packages. We summarize all of the results from the UCNA experiment, obtained during run periods in 2007, 2008â2009, 2010, and 2011â2013, which ultimately culminated in a 0.67% precision result for Aâ
First Direct Constraints on Fierz Interference in Free-Neutron \u3cem\u3eÎČ\u3c/em\u3e Decay
Precision measurements of free-neutron ÎČ decay have been used to precisely constrain our understanding of the weak interaction. However, the neutron Fierz interference term bn, which is particularly sensitive to beyond-standard-model tensor currents at the TeV scale, has thus far eluded measurement. Here we report the first direct constraints on this term, finding bn = 0.067 ± 0.005stat+0.090-0.061sys, consistent with the standard model. The uncertainty is dominated by absolute energy reconstruction and the linearity of the ÎČ spectrometer energy response