22 research outputs found
Experimental Status of Neutrino Physics
After a fascinating phase of discoveries, neutrino physics still has a few
mysteries such as the absolute mass scale, the mass hierarchy, the existence of
CP violation in the lepton sector and the existence of right-handed neutrinos.
It is also entering a phase of precision measurements. This is what motivates
the NUFACT 11 conference which prepares the future of long baseline neutrino
experiments. In this paper, we report the status of experimental neutrino
physics. We focus mainly on absolute mass measurements, oscillation parameters
and future plans for oscillation experiments
Recoilless Resonant Absorption of Monochromatic Neutrino Beam for Measuring Delta m^2_{31} and theta_{13}
We discuss, in the context of precision measurement of Delta m^2_{31} and
theta_{13}, physics capabilities enabled by the recoilless resonant absorption
of monochromatic antineutrino beam enhanced by the M\"ossbauer effect recently
proposed by Raghavan. Under the assumption of small relative systematic error
of a few tenth of percent level between measurement at different detector
locations, we give analytical and numerical estimates of the sensitivities to
Delta m^2_{31} and sin^2 2theta_{13}. The accuracies of determination of them
are enormous; The fractional uncertainty in Delta m^2_{31} achievable by 10
point measurement is 0.6% (2.4%) for sin^2 2theta_{13} = 0.05, and the
uncertainty of sin^2 2theta_{13} is 0.002 (0.008) both at 1 sigma CL with the
optimistic (pessimistic) assumption of systematic error of 0.2% (1%). The
former opens a new possibility of determining the neutrino mass hierarchy by
comparing the measured value of Delta m^2_{31} with the one by accelerator
experiments, while the latter will help resolving the theta_{23} octant
degeneracy.Comment: 23 pages, 3 figures, version to appear in New Journal of Physic
New measurement of via neutron capture on hydrogen at Daya Bay
This article reports an improved independent measurement of neutrino mixing
angle at the Daya Bay Reactor Neutrino Experiment. Electron
antineutrinos were identified by inverse -decays with the emitted
neutron captured by hydrogen, yielding a data-set with principally distinct
uncertainties from that with neutrons captured by gadolinium. With the final
two of eight antineutrino detectors installed, this study used 621 days of data
including the previously reported 217-day data set with six detectors. The
dominant statistical uncertainty was reduced by 49%. Intensive studies of the
cosmogenic muon-induced Li and fast neutron backgrounds and the
neutron-capture energy selection efficiency, resulted in a reduction of the
systematic uncertainty by 26%. The deficit in the detected number of
antineutrinos at the far detectors relative to the expected number based on the
near detectors yielded in the
three-neutrino-oscillation framework. The combination of this result with the
gadolinium-capture result is also reported.Comment: 26 pages, 23 figure
A side-by-side comparison of Daya Bay antineutrino detectors
The Daya Bay Reactor Neutrino Experiment is designed to determine precisely
the neutrino mixing angle with a sensitivity better than 0.01 in
the parameter sin at the 90% confidence level. To achieve this
goal, the collaboration will build eight functionally identical antineutrino
detectors. The first two detectors have been constructed, installed and
commissioned in Experimental Hall 1, with steady data-taking beginning
September 23, 2011. A comparison of the data collected over the subsequent
three months indicates that the detectors are functionally identical, and that
detector-related systematic uncertainties exceed requirements.Comment: 24 pages, 36 figure