Professor Umran Inan

Winter 2001-2002

Date: Wednesday, January 16, 2002
Time: 4:15 PM; Refreshments at 4:00 PM
Stanford University

Time Series Analysis of the Solar Neutrino Flux - Is There a Signal in the Noise?

Prof. Peter Sturrock
Applied Physics and Physics


Several experiments have been collecting solar neutrino data for many years. Most of the available data comes from radiochemical experiments, which produce an estimate of the neutrino flux every three or four weeks. In each "run," only a few neutrinos are captured. As a result, the measurements are both coarse and noisy. Attempts to correlate these measurements with sunspot data, etc., have been unconvincing.

Most forms of radiation from the Sun exhibit a strong oscillation with a period of order 27 days due to solar rotation. In this seminar, we shall describe our search for similar oscillations in the solar neutrino flux. On the face of it, this is not a very promising exercise, since we are looking for oscillations with periods comparable with the sampling interval and, indeed, with the integration interval. We shall argue that, despite these very real difficulties, it is still possible to search for a solar-rotation signal by means of time-series analysis. We shall present the present evidence that the neutrino flux is indeed modulated by solar rotation, and we shall discuss, very briefly, the significance of this result.