14 research outputs found
A radium assay technique using hydrous titanium oxide adsorbent for the Sudbury Neutrino Observatory
As photodisintegration of deuterons mimics the disintegration of deuterons by
neutrinos, the accurate measurement of the radioactivity from thorium and
uranium decay chains in the heavy water in the Sudbury Neutrino Observatory
(SNO) is essential for the determination of the total solar neutrino flux. A
radium assay technique of the required sensitivity is described that uses
hydrous titanium oxide adsorbent on a filtration membrane together with a
beta-alpha delayed coincidence counting system. For a 200 tonne assay the
detection limit for 232Th is a concentration of 3 x 10^(-16) g Th/g water and
for 238U of 3 x 10^(-16) g U/g water. Results of assays of both the heavy and
light water carried out during the first two years of data collection of SNO
are presented.Comment: 12 pages, 4 figure
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
Measurement of the νe and total 8B solar neutrino fluxes with the Sudbury Neutrino Observatory phase-III data set
This paper details the solar neutrino analysis of the 385.17-day phase-III data set acquired by the Sudbury Neutrino Observatory (SNO). An array of 3He proportional counters was installed in the heavy-water target to measure precisely the rate of neutrino-deuteron neutral-current interactions. This technique to determine the total active 8B solar neutrino flux was largely independent of the methods employed in previous phases. The total flux of active neutrinos was measured to be 5.54-0.31+0.33(stat.)-0.34+0.36(syst.)×106 cm-2 s-1, consistent with previous measurements and standard solar models. A global analysis of solar and reactor neutrino mixing parameters yielded the best-fit values of Δm2=7.59-0.21+0.19×10 -5eV2 and θ=34.4-1.2+1.3degrees
Recent results from SNO
The SNO project has now completed two of its three major phases of operation. The no-oscillation hypothesis has been ruled out at 5σ in the pure heavy water phase and 8σ in the salt phase. Discussion in terms of the SeeSaw model is presented
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
Neutral current and day night measurements from the pure D2O phase of SNO
The Sudbury Neutrino Observatory is a 1000 T D2O Cerenkov detector that is sensitive to 8B solar neutrinos. The energy, radius, and direction with respect to the sun is measured for each neutrino event; these distributions are used to separately determine the rates of the charged current, neutral current and electron scattering reactions of neutrinos on deuterium. Assuming an undistorted 8B spectrum, the νe component of the 8B solar flux is φe = 1.76-0.05 +0.05 (stat. -0.09 +0.09 (syst.) × 106 cm-2s-1 based on events with a measured kinetic energy above 5 MeV. The non-νe component is φμτ = 3.41-0.45 +0.45 (stat. -0.45 +0.48 (syst.) × 106 cm-2s-1, 5.3σ greater than zero, providing strong evidence for solar νe flavor transformation. The total flux measured with the NC reaction is φNC = 5.09-0.43 +0.44(stat. -0.43 +0.46 (syst.) × 106 cm-2s-1, consistent with solar models. The night minus day rate is 14.0% ± 6.3%-1.4 +1.5% of the average rate. If the total flux of active neutrinos is additionally constrained to have no asymmetry, the νe asymmetry is found to be 7.0% ± 4.9%-1.2 +1.3%. A global solar neutrino analysis in terms of matter-enhanced oscillations of two active flavors strongly favors the Large Mixing Angle (LMA) solution