The Sudbury Neutrino Observatory

The Sudbury Neutrino Observatory is a second generation water Cherenkov detector designed to determine whether the currently observed solar neutrino deficit is a result of neutrino oscillations. The detector is unique in its use of D2O as a detection medium, permitting it to make a solar model-independent test of the neutrino oscillation hypothesis by comparison of the charged- and neutral-current interaction rates. In this paper the physical properties, construction, and preliminary operation of the Sudbury Neutrino Observatory are described. Data and predicted operating parameters are provided whenever possible.Comment: 58 pages, 12 figures, submitted to Nucl. Inst. Meth. Uses elsart and epsf style files. For additional information about SNO see http://www.sno.phy.queensu.ca . This version has some new reference

Estimate of the optimal level of concentrates for dairy cows on tropical pastures by using the concept of marginal analysis Estimativa do nível ótimo de concentrado para vacas leiteiras em pastos tropicais utilizando-se o conceito de análise marginal

It was adopted in this work a methodology to estimate the optimal level of concentrate food for dairy cows on tropical pastures based on the theory of marginal analysis. An empiric model was developed and validated for application of the methodology using a database composed of 62 means of treatments from 32 studies in which milk production was evaluated regarded to the levels of concentrate feeding. Milk production (MP) showed quadratic behavior in response to concentrate intake (CI): MP (kg/cow/day) = 10.554 + 1.5855CI - 0.0552CI². Evaluation of the MP values observed over the predicted ones pointed the non-rejection of the null hypothesis, indicating that the model can be applied on the prediction of milk production, and consequently, on the optimal level of supplementation. However, evaluation of the partition of mean square error of prediction indicated the need for adjustments. The marginal production response (MPR) presented decreasing linear effect at CI level: MPR (kg milk/kg concentrate added) = 1.5855 - 0.1104CI. The intake of concentrate that maximizes profit per animal (CIoptimum) is estimated by the following equation: CIoptimum (kg/cow/day, as fed basis) = (1.5855 - (Px/Py))/0.1104; in which Px and Py are, respectively, the prices of concentrate feeds ($/kg, as fed basis) and of the milk at farmgate ($/kg). It is suggested the realization of new studies to include in the model, indicators of reproductive performance and other factors that affect the productive response to supplementation with concentrate feeds. Recommendations on levels of concentrate feeding for bovines should be based on presuppotions of marginal response theory, in order to avoid irrational use of nutrients.<br>Adotou-se uma metodologia para estimar o nível ótimo de alimentos concentrados para vacas leiteiras em pastos tropicais com base na teoria da análise marginal. Um modelo empírico foi desenvolvido e validado para aplicação da metodologia, utilizando-se um banco de dados formado por 62 médias de tratamentos oriundos de 31 estudos em que a produção de leite foi avaliada em relação aos níveis de alimentação concentrada. A produção de leite (PL) apresentou comportamento quadrático em resposta ao consumo de concentrado (CC): PL (kg/vaca/dia) = 10,554 + 1,5855CC - 0,0552CC². A avaliação dos valores de produção de leite observados sobre os preditos de PL apontou a não-rejeição da hipótese de nulidade, indicando que o modelo pode ser aplicado na predição da produção de leite e, consequentemente, do nível ótimo de suplementação. No entanto, a avaliação da partição do quadrado médio do erro de predição do modelo indicou a necessidade de ajustamentos. A resposta produtiva marginal (RPMa) apresentou comportamento linear decrescente ao nível de CC: RPMa (kg leite/ kg de concentrado adicionado) = 1,5855 - 0,1104CC. O consumo de concentrado que maximiza o lucro por animal (CCótimo) é estimado pela seguinte equação: CCótimo (kg/vaca/dia, com base na matéria natural) = (1,5855 - (Px/Py))/0,1104; em que Px e Py são, respectivamente, os preços do concentrado (R$/kg de matéria natural) e do leite recebido pelo produtor (R$/kg). Sugere-se a realização de novos estudos para incorporar ao modelo indicadores de desempenho reprodutivo e outros fatores que afetam a resposta produtiva à suplementação com alimentos concentrados. Recomendações de níveis de suplementação com alimentos concentrados para bovinos devem basear-se nos pressupostos da teoria da análise marginal sob o risco de uso irracional dos nutrientes

Measurement of the nue and Total 8B Solar Neutrino Fluxes with the Sudbury Neutrino Observatory Phase I Data Set

This article provides the complete description of results from the Phase I data set of the Sudbury Neutrino Observatory (SNO). The Phase I data set is based on a 0.65 kt-year exposure of heavy water to the solar 8B neutrino flux. Included here are details of the SNO physics and detector model, evaluations of systematic uncertainties, and estimates of backgrounds. Also discussed are SNO's approach to statistical extraction of the signals from the three neutrino reactions (charged current, neutral current, and elastic scattering) and the results of a search for a day-night asymmetry in the ?e flux. Under the assumption that the 8B spectrum is undistorted, the measurements from this phase yield a solar ?e flux of ?(?e) = 1.76+0.05?0.05(stat.)+0.09?0.09 (syst.) x 106 cm?2 s?1, and a non-?e component ?(? mu) = 3.41+0.45?0.45(stat.)+0.48?0.45 (syst.) x 106 cm?2 s?1. The sum of these components provides a total flux in excellent agreement with the predictions of Standard Solar Models. The day-night asymmetry in the ?e flux is found to be Ae = 7.0 +- 4.9 (stat.)+1.3?1.2 percent (sys.), when the asymmetry in the total flux is constrained to be zero

First neutrino observations from the sudbury neutrino observatory

The first neutrino observations from the Sudbury Neutrino Observatory are presented from preliminary analyses. Based on energy, direction and location, the data in the region of interest appear to be dominated by 8B solar neutrinos, detected by the charged current reaction on deuterium and elastic scattering from electrons, with very little background. Measurements of radioactive backgrounds indicate that the measurement of all active neutrino types via the neutral current reaction on deuterium will be possible with small systematic uncertainties. Quantitative results for the fluxes observed with these reactions will be provided when further calibrations have been completed

Measurement of CC interactions produced by8B solar neutrinos at SNO

The Sudbury Neutrino Observatory (SNO) is a 1000 tonne heavy water Cherenkov detector placed 2 km underground in Ontario, Canada. Its main purpose is the detection of solar neutrinos, but it is also sensitive to atmospheric and supernova neutrinos. In this paper we report our first measurement of the solar electron-type neutrino flux using the charged current interaction on deuterium, above an electron kinetic energy threshold of 6.75 MeV. This measurement, when compared with an electron scattering measurement from Super Kamiokande, provides the first evidence for non-electron neutrino types from the Sun implying flavor change of solar electron neutrinos. We also present an initial angular distribution of through-going muons, which shows that we can detect neutrino-induced muons from well above the horizontal. This will give us good sensitivity to neutrino oscillations in the atmospheric sector