Gaussian curves are infinite in length., so it isn't clear what your criterion would be for where they start/stop. However, a good place to start would probably be to use the Curve Fitting Toolbox to fit a three-term Gaussian model ( 'gauss3' ).
s=load('req_data.mat').drt_data;
x=s.tau;
y=s.gamma_tau*1e4;
a=[1.5,0.5,6];
b=[-2,-0.3,1.4];
c=[1,0.5,1];
x0=[a;b;c];
ft=fit(x,y,'gauss3','StartPoint',x0(:).');
plot(ft,x,y)
