Search for time modulations in the Gallex/GNO solar neutrino data

The final data of the Gallex and GNO radiochemical experiments have been searched for possible time modulations of the solar neutrino capture rate using the Lomb-Scargle periodogram and the maximum likelihood methods. Both analyses, performed using the raw data, do not support the presence of a time variability with characteristic periods resembling those of rotation of the solar magnetic fields, as previously suggested in the literature by some authors. In this context, the potential sensitivity of the Lomb-Scargle method to radiochemical Ga-71 data has also been explored with simulated data. This allowed to set an exclusion plot in the frequency/amplitude plane from the Gallex-GNO dataset. (C) 2004 Elsevier B.V. All rights reserved.