A search has been performed for neutrinos from two sources, the hep reaction in the solar pp fusion chain and the νe component of the diffuse supernova neutrino background (DSNB), using the full ...dataset of the Sudbury Neutrino Observatory with a total exposure of 2.47 kton − years after fiducialization. The hep search is performed using both a single-bin counting analysis and a likelihood fit. We find a best-fit flux that is compatible with solar model predictions while remaining consistent with zero flux, and set a one-sided upper limit of Φhep < 30 × 103 cm−2 s−1 90% credible interval (CI). No events are observed in the DSNB search region, and we set an improved upper bound on the νe component of the DSNB flux of ΦνeDSNB < 19 cm−2 s−1 (90% CI) in the energy range 22.9 < Eν < 36.9 MeV.
The Russian-American solar neutrino experiment has measured the capture rate of neutrinos on metallic gallium in a radiochemical experiment at the Baksan Neutrino Observatory. Eight years of ...measurement give the result 67.2{sup +7.2+3.5}{sub -7.0-3.0} solar neutrino units, where the uncertainties are statistical and systematic, respectively. The restrictions these results impose on vacuum neutrino oscillation parameters are given. (c) 1999 The American Physical Society.
Experimental tests of Lorentz symmetry in systems of all types are critical for ensuring that the basic assumptions of physics are well founded. Data from all phases of the Sudbury Neutrino ...Observatory, a kiloton-scale heavy water Cherenkov detector, are analyzed for possible violations of Lorentz symmetry in the neutrino sector. Such violations would appear as one of eight possible signal types in the detector: six seasonal variations in the solar electron neutrino survival probability differing in energy and time dependence and two shape changes to the oscillated solar neutrino energy spectrum. No evidence for such signals is observed, and limits on the size of such effects are established in the framework of the standard model extension, including 38 limits on previously unconstrained operators and improved limits on 16 additional operators. This makes limits on all minimal, Dirac-type Lorentz violating operators in the neutrino sector available for the first time.
Observations of neutral-current nu interactions on deuterium in the Sudbury Neutrino Observatory are reported. Using the neutral current (NC), elastic scattering, and charged current reactions and ...assuming the standard 8B shape, the nu(e) component of the 8B solar flux is phis(e) = 1.76(+0.05)(-0.05)(stat)(+0.09)(-0.09)(syst) x 10(6) cm(-2) s(-1) for a kinetic energy threshold of 5 MeV. The non-nu(e) component is phi(mu)(tau) = 3.41(+0.45)(-0.45)(stat)(+0.48)(-0.45)(syst) x 10(6) cm(-2) s(-1), 5.3sigma greater than zero, providing strong evidence for solar nu(e) flavor transformation. The total flux measured with the NC reaction is phi(NC) = 5.09(+0.44)(-0.43)(stat)(+0.46)(-0.43)(syst) x 10(6) cm(-2) s(-1), consistent with solar models.
Neutrino mass measurements Wark, D. L.
Philosophical transactions of the Royal Society of London. Series A: Mathematical, physical, and engineering sciences,
11/2003, Letnik:
361, Številka:
1812
Journal Article
Recenzirano
Before we can be sure we have a dark-matter problem we have to first be certain that no known particle can account for the missing matter. The last possibility has long been the neutrino, which, ...while massless in the Standard Model of particle physics, is the second most numerous particle in the Universe (after the photon) and thus (if massive) a potential source of substantial unaccounted for mass. Recent neutrino oscillation measurements have, in fact, confirmed that the Standard Model is incomplete and that neutrinos have mass. However, recent measurements have confirmed that the resulting mass is insufficient for neutrinos to make up the bulk of the dark matter. In fact, observations of the matter distribution in the Universe are now competing with laboratory measurements in their sensitivity to the absolute masses of neutrinos. The article discusses all these measurements and gives some guesses about where we may get in our measurements of neutrino masses in the future.
Neutrons produced in nuclear interactions initiated by cosmic-ray muons present an irreducible background to many rare-event searches, even in detectors located deep underground. Models for the ...production of these neutrons have been tested against previous experimental data, but the extrapolation to deeper sites is not well understood. Here we report results from an analysis of cosmogenically produced neutrons at the Sudbury Neutrino Observatory. A specific set of observables are presented, which can be used to benchmark the validity of geant4 physics models. In addition, the cosmogenic neutron yield, in units of 10−4 cm2/(g·μ), is measured to be 7.28±0.09(stat)−1.12+1.59(syst) in pure heavy water and 7.30±0.07(stat)−1.02+1.40(syst) in NaCl-loaded heavy water. These results provide unique insights into this potential background source for experiments at SNOLAB.
The authors investigated the effects of gender, gender role, and type of moral dilemma on moral maturity and moral orientation. Fifty-five female and 55 male university students were given the
...Personal Attributes Questionnaire
(
J. T. Spence & R. L. Helmreich, 1978
),
L. Kohlberg's test of moral judgment, and instructions to discuss a personal and impersonal real-life moral dilemma. Moral stage, moral orientation, and the relation between them varied across dilemmas. Females were more consistent than males in moral stage; males were more consistent in moral orientation. Females made higher stage and more care-based moral judgments than males made on personal real-life dilemmas. The observed variations occurred primarily because males reported more Stage 2, justice-pulling antisocial dilemmas than females, and females reported more Stage 3, care-pulling prosocial dilemmas than males. A more interactional model of moral judgment than the models of L. Kohlberg and C. Gilligan is recommended.
Since the late 1980s, satellite-based global positioning systems (GPS) have provided unique and novel data that have been used to track animal movement. Tracking animals with GPS can provide useful ...information, but the cost of the technology often limits experimental replication. Limitations on the number of devices available to monitor the behaviour of animals, in combination with technical constraints, can weaken the statistical power of experiments and create significant experimental design challenges. The present paper provides a review and synthesis of using GPS for livestock-based studies and suggests some future research directions. Wildlife ecologists working in extensive landscapes have pioneered the use of GPS-based devices for tracking animals. Wildlife researchers have focussed efforts on quantifying and addressing issues associated with technology limitations, including spatial accuracy, rate of data collection, battery life and environmental factors causing loss of data. It is therefore not surprising that there has been a significant number of methodological papers published in the literature that have considered technical developments of GPS-based animal tracking. Livestock scientists have used GPS data to inform them about behavioural differences in free-grazing experiments. With a shift in focus from the environment to the animal comes the challenge of ensuring independence of the experimental unit. Social facilitation challenges independence of the individual in a group. The use of spatial modelling methods to process GPS data provides an opportunity to determine the degree of independence of data collected from an individual animal within behavioural-based studies. By using location and movement information derived from GPS data, researchers have been able to determine the environmental impact of grazing animals as well as assessing animal responses to management activities or environmental perturbations. Combining satellite-derived remote-sensing data with GPS-derived landscape preference indices provides a further opportunity to identify landscape avoidance and selection behaviours. As spatial livestock monitoring tools become more widely used, there will be a greater need to ensure the data and associated processing methods are able to answer a broader range of questions. Experimental design and analytical techniques need to be given more attention if GPS technology is to provide answers to questions associated with free-grazing animals.
The Sudbury Neutrino Observatory (SNO) has measured day and night solar neutrino energy spectra and rates. For charged current events, assuming an undistorted 8B spectrum, the night minus day rate is ...14.0%+/-6.3%(+1.5%)(-1.4%) of the average rate. If the total flux of active neutrinos is additionally constrained to have no asymmetry, the nu(e) asymmetry is found to be 7.0%+/-4.9%(+1.3%)(-1.2%). A global solar neutrino analysis in terms of matter-enhanced oscillations of two active flavors strongly favors the large mixing angle solution.
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