Matter profile effect in a neutrino factory - art. no. 093004

We point out that the matter profile effect-the effect of matter density fl uctuation on the baseline-is very important to estimate the parameters in a neutrino factory with a very long baseline. To make it clear, we propose t he method of Fourier series expansion of the matter profile. By using this method, we can take account of both the matter profile effect and its ambig uity. For very long baseline experiment, such as L = 7332 km, in the analys is of the oscillation phenomena we need to introduce a new parameter a(1)-t he Fourier coefficient of the matter profile-as a theoretical parameter to deal with the matter profile effects.