Steve Biller

Abstract:

A search has been made for sinusoidal periodic variations in the B8 solar neutrino flux using data collected by the Sudbury Neutrino Observatory over a 4-year time interval. The variation at a period of 1 yr is consistent with modulation of the B8 neutrino flux by the Earth's orbital eccentricity. No significant sinusoidal periodicities are found with periods between 1 d and 10 years with either an unbinned maximum likelihood analysis or a Lomb-Scargle periodogram analysis. The data are inconsistent with the hypothesis that the results of the recent analysis by Sturrock et al., based on elastic scattering events in Super-Kamiokande, can be attributed to a 7% sinusoidal modulation of the total B8 neutrino flux. © 2005 The American Physical Society.

Abstract:

Results are reported from the complete salt phase of the Sudbury Neutrino Observatory experiment in which NaCl was dissolved in the H22O ("D2O") target. The addition of salt enhanced the signal from neutron capture as compared to the pure D2O detector. By making a statistical separation of charged-current events from other types based on event-isotropy criteria, the effective electron recoil energy spectrum has been extracted. In units of 106cm-2s-1, the total flux of active-flavor neutrinos from B8 decay in the Sun is found to be 4.94-0.21+0.21(stat)-0.34+0.38(syst) and the integral flux of electron neutrinos for an undistorted B8 spectrum is 1.68-0.06+0.06(stat)-0. 09+0.08(syst); the signal from (νx,e) elastic scattering is equivalent to an electron-neutrino flux of 2.35-0.22+0.22(stat)-0.15+0.15(syst). These results are consistent with those expected for neutrino oscillations with the so-called large mixing angle parameters and also with an undistorted spectrum. A search for matter-enhancement effects in the Earth through a possible day-night asymmetry in the charged-current integral rate is consistent with no asymmetry. Including results from other experiments, the best-fit values for two-neutrino mixing parameters are Δm2=(8.0-0.4+0.6)×10-5 eV2 and θ=33.9-2.2+2.4 degrees. © 2005 The American Physical Society.

Abstract:

With the next generation of Atmospheric Cerenkov Telescopes (ACT) well on their way, effort has being shifted now towards a further improvement of the capabilities of these instruments. These next generation experiments have improved up to an order of magnitude their sensitivity over their first generation Counterparts. and have extended the energy coverage down to about 50 GeV. However, it is not clear whether the same approach is optimal for energies above 1 TcV. and with clear evidence of high energy emission above this energy from several astrophysical sources, we believe that this energy range could be further exploited. Many of our physics goals, such as, limits on quantum gravity or spectral variability and features of the high energy emission from AGNs. would benefit from an increase of sensitivity in this direction. Here, we investigate a possible way of increasing the collection area of ACTs above 1 TeV by using a wide-field-of-view (similar to 10 degrees) camera. Both, the scientific motivation and preliminary Monte Carlo Studies of the performance of such a detector, are discussed and presented here.