Reconstruction of solar activity variations in the past by measurement of cosmogenic radioisotopes in meteorites

Abstract

Many reconstructions of solar activity variations in the past are based on the measurement of cosmogenic isotopes (such as ¹⁴C and ¹⁰Be) stored in terrestrial archives. The concentration of these isotopes is however influenced by terrestrial phenomena. In order to avoid this problem our group is studying cosmogenic radioisotopes in meteorites at the underground laboratory of Monte dei Cappuccini in Torino (Italy). Measurement of ⁴⁴Ti decay activity in 21 meteorites has revealed a centennial oscillation superimposed on a decreasing trend of the cosmic ray flux in the last 235 years. The decreasing trend is consistent with some models based on solar open magnetic field variations. We show some preliminary results obtained using a new acquisition system we have recently developed and set up in order to enhance selectivity of ⁴⁴Ti detection.