In the solar neutrino experiments, there were deficits in the observed solar neutrino flux when compared with the theoretical values. If i just focus on the Cl-37 and Ga-71 reactions to detect solar neutrinos, there is a question confuses me a lot. That is, from the result of experiment done by Davis (using Cl-37), the ratio of the observed flux to the expected flux was about 0.29. However, from the result of SAGE and GALLEX (using Ga-71) at later time, the ratio were about 0.55-0.60, which were much different from the previous case. Does anyone know the reason behind?? Thank you very much! Reference: J.N.Abdura****ov et al., in Results from SAGE (The Russian American Gallium Experiment), Phys. Lett. B328 (1994) 223-248 P.S. the name cannot be displayed...:grumpy: it should be "J.N. Abdurash_itov" without "_"..