src_cross="max_g2.dat"
set terminal postscript  eps color enhanced solid font "Helvetica,17" size 10cm, 8cm
set bar 0
#set border 1023-128
set output "gsi.eps"
set isosamples 40,40
set samples 1000,1000
set size 1,0.8
set origin 0,0
unset label
set ylabel font "Helvetica,17" "G_{SI}^{(2)}"
set ytics 100 nomirror font "Helvetica,16"
set xtics 10 nomirror scale 0.5 font "Helvetica,16"
set y2range [0:17.5]
set y2tics 4.1 font "Helvetica,14"
set y2label font "Helvetica,17" "g_{SI}^{(2)} ({/Symbol \664} 10^3)"
set xlabel font "Helvetica,17" "{/Symbol D}t_{SI} (ns)" #at first 3, first -50 
set label font "Helvetica,16" "g_{SI}^{(2)}(0)= \n\n 14600(121) " at first -28, first 300
f(x)=B+A*exp(-(x-x0)/C)
B=0.1;A=350;C=4;x0=0.01;
fit [1:] f(x) src_cross u ($1-328):2 via A,B,C,x0

plot [-40:40][0:420] src_cross u ($1-328):2:(sqrt($2))w yerrorbars notitle pt 7 ps 1 lc rgb "red", f(x) lc rgb "blue" lw 2 lt 2 notitle

# 'coincidence_left.dat' u ($1-3):($2*2400) w l lc rgb "#555555" lw 2 lt 3 #notitle,'coincidence_left.dat' u ($1+27):($2*2400) w l lc rgb "#555555" lw 2 lt 3 notitle