function y = least_square_backscattering(x0,conc,count,count_air,count_blank);

R=0.05;%distance to insonified volume
diff_count=count_blank-count_air;
y=sum((count-(count_air-2*R*x0(1)*conc+x0(2)*10*log10(x0(3)*conc+10^(diff_count/10/x0(2))))).^2);

 