2,248 research outputs found
Neutrino Oscillations at Reactors: What Next?
We shortly review past and future experiments at reactors aimed at searches
for neutrino masses and mixing. We also consider new idea to search at
Krasnoyarsk for small mixing angle oscillations in the atmosheric neutrino mass
parameter region.Comment: 9 pages, LaTeX 2.09, 6 Postscript figures. Talk given at
Non-Accelerator New Physics Conference, Dubna, 28.06-03.07.199
The Kr2Det project: Search for mass-3 state contribution |U_{e3}|^2 to the electron neutrino using a one reactor - two detector oscillation experiment at Krasnoyarsk underground site
The main physical goal of the project is to search with reactor antineutrinos
for small mixing angle oscillations in the atmospheric mass parameter region
around {\Delta}m^{2}_{atm} ~ 2.5 10^{-3} eV^2 in order to find the element
U_{e3} of the neutrino mixing matrix or to set a new more stringent constraint
(U_{e3} is the contribution of mass-3 state to the electron neutrino flavor
state). To achieve this we propose a "one reactor - two detector" experiment:
two identical antineutrino spectrometers with 50 ton liquid scintillator
targets located at ~100 m and ~1000 m from the Krasnoyarsk underground reactor
(~600 mwe). In no-oscillation case ratio of measured positron spectra of the
\bar{{\nu}_e} + p \to e^{+} + n reaction is energy independent. Deviation from
a constant value of this ratio is the oscillation signature. In this scheme
results do not depend on the exact knowledge of the reactor power, nu_e
spectra, burn up effects, target volumes and, which is important, the
backgrounds can periodically be measured during reactor OFF periods. In this
letter we present the Krasnoyarsk reactor site, give a schematic description of
the detectors, calculate the neutrino detection rates and estimate the
backgrounds. We also outline the detector monitoring and calibration
procedures, which are of a key importance. We hope that systematic
uncertainties will not accede 0.5% and the sensitivity U^{2}_{e3} ~4 10^{-3}
(at {\Delta}m^{2} = 2.5 10^{-3} eV^2) can be achieved.Comment: Latex 2e, 9 pages and 5 ps figure
Low Energy Neutrino Physics after SNO and KamLAND
In the recent years important discoveries in the field of low energy neutrino
physics (E in the MeV range) have been achieved. Results of the
solar neutrino experiment SNO show clearly flavor transitions from to
. In addition, the long standing solar neutrino problem is
basically solved. With KamLAND, an experiment measuring neutrinos emitted from
nuclear reactors at large distances, evidence for neutrino oscillations has
been found. The values for the oscillation parameters, amplitude and phase,
have been restricted. In this paper the potential of future projects in low
energy neutrino physics is discussed. This encompasses future solar and reactor
experiments as well as the direct search for neutrino masses. Finally the
potential of a large liquid scintillator detector in an underground laboratory
for supernova neutrino detection, solar neutrino detection, and the search for
proton decay is discussed.Comment: Invited brief review, World Scientific Publishing Compan
The role of building control surveyors and their power in promoting sustainable construction
In England, building regulations govern aspects of a building’s environmental performance. The Building Control Surveyor reviews designs and on-site construction in order to evaluate, and ultimately certify, compliance with the regulations, but little research has been carried out to investigate the role of these professionals in promoting sustainable construction. A qualitative study was conducted, comprising semi-structured interviews with 21 building control surveyors and 4 key informants from professional bodies in England. The building surveyors initially positioned their power as wholly derived from the regulations, thus constraining their contribution on sustainability to regulation enforcement. However, this stood in contradiction to their recognition of being valued and influential members of the project team. Descriptions of day-to-day activities included sharing common goals with the team, providing guidance based on their knowledge and experience, and developing collaborative relationships. Based on theories of power, these practices may be seen as processes of power. The primary conclusion is that building control surveyors are indeed powerful in the project team, and, with greater recognition of the varied forms of power available to them above and beyond regulatory certification, they could extend their influence in daily working interactions to promote more sustainable construction
Inverse Beta Decay in a Nonequilibrium Antineutrino Flux from a Nuclear Reactor
The evolution of the reactor antineutrino spectrum toward equilibrium above
the inverse beta-decay threshold during the reactor operating period and the
decay of residual antineutrino radiation after reactor shutdown are considered.
It is found that, under certain conditions, these processes can play a
significant role in experiments seeking neutrino oscillations.Comment: 8 pages including 5 ps figure
The symmetry of charge order in cuprates
Charge-ordered ground states permeate the phenomenology of 3d-based
transition metal oxides, and more generally represent a distinctive hallmark of
strongly-correlated states of matter. The recent discovery of charge order in
various cuprate families fueled new interest into the role played by this
incipient broken symmetry within the complex phase diagram of high-Tc
superconductors. Here we use resonant X-ray scattering to resolve the main
characteristics of the charge-modulated state in two cuprate families: Bi2201
and YBCO. We detect no signatures of spatial modulations along the nodal
direction in Bi2201, thus clarifying the inter-unit-cell momentum-structure of
charge order. We also resolve the intra-unit-cell symmetry of the charge
ordered state, which is revealed to be best represented by a bond-order with
modulated charges on the O-2p orbitals and a prominent d-wave character. These
results provide insights on the microscopic description of charge order in
cuprates, and on its origin and interplay with superconductivity.Comment: A high-resolution version with supplementary material can be found
at:
http://www.phas.ubc.ca/~quantmat/ARPES/PUBLICATIONS/Articles/CDW_symmetry.pd
Muon-anti-neutrino <---> electron-anti-neutrino mixing: analysis of recent indications and implications for neutrino oscillation phenomenology
We reanalyze the recent data from the Liquid Scintillator Neutrino Detector
(LSND) experiment, that might indicate anti-nu_muanti-nu_e mixing. This
indication is not completely excluded by the negative results of established
accelerator and reactor neutrino oscillation searches. We quantify the region
of compatibility by means of a thorough statistical analysis of all the
available data, assuming both two-flavor and three-flavor neutrino
oscillations. The implications for various theoretical scenarios and for future
oscillation searches are studied. The relaxation of the LSND constraints under
different assumptions in the statistical analysis is also investigated.Comment: 17 pages (RevTeX) + 9 figures (Postscript) included with epsfig.st
Neutrino mass matrix with U(2) flavor symmetry and neutrino oscillations
The three neutrino mass matrices in the model are studied
focusing on the neutrino oscillation experiments. The atmospheric neutrino
anomaly could be explained by the large oscillation.
The long baseline experiments are expected to detect signatures of the neutrino
oscillation even if the atmospheric neutrino anomaly is not due to the neutrino
oscillation. However, the model cannot solve the solar neutrino deficit while
it could be reconciled with the LSND data.Comment: 12 pages, LaTex file, to be published in PR
A new ordering principle for the classical statistical analysis of Poisson processes with background
Inspired by the recent proposal by Feldman and Cousins of a ``unified
approach to the classical statistical analysis of small signals'' based on a
choice of ordering in Neyman's construction of classical confidence intervals,
I propose a new ordering principle for the classical statistical analysis of
Poisson processes with background which minimizes the effect on the resulting
confidence intervals of the observation of less background events than
expected. The new ordering principle is applied to the calculation of the
confidence region implied by the recent null result of the KARMEN neutrino
oscillation experiment.Comment: 16 pages including 5 figures, RevTeX. Final version published in
Phys. Rev. D 59 (1999) 05300
Limits on the neutrino magnetic moment from the MUNU experiment
The MUNU experiment was carried out at the Bugey nuclear power reactor. The
aim was the study of electron antineutrino-electron elastic scattering at low
energy. The recoil electrons were recorded in a gas time projection chamber,
immersed in a tank filled with liquid scintillator serving as veto detector,
suppressing in particular Compton electrons. The measured electron recoil
spectrum is presented. Upper limits on the neutrino magnetic moment were
derived and are discussed.Comment: 9 pages, 7 figures Added reference: p.3, 1st col., TEXONO Added
sentence: p.4, 1st col., electron attachement Modified sentence: p.5, 1st
col., readout sequence Added sentence: p.5, 1st col., fast rise time cu
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