nmax_050 = 15000./100000;
nmin_075 = 15001./100000;
nmax_075 = 27290./100000;
nmin_100 = 27291./100000;
nmax_100 = 37590./100000;
nmin_125 = 37591./100000;
nmax_125 = 46310./100000;
nmin_150 = 46311./100000;
nmax_150 = 53760./100000;
nmin_175 = 53761./100000;
nmax_175 = 60140./100000;
nmin_200 = 60141./100000;
nmax_200 = 65680./100000;
nmin_225 = 65681./100000;
nmax_225 = 70460./100000;
nmin_250 = 70461./100000;
nmax_250 = 74630./100000;
nmin_275 = 74631./100000;
nmax_275 = 78290./100000;
nmin_300 = 78291./100000;
nmax_300 = 81510./100000;
nmin_325 = 81511./100000;
nmax_325 = 84330./100000;
nmin_350 = 84331./100000;
nmax_350 = 86860./100000;
nmin_375 = 86861./100000;
nmax_375 = 89090./100000;
nmin_400 = 89091./100000;
nmax_400 = 91060./100000;
nmin_425 = 91061./100000;
nmax_425 = 92790./100000;
nmin_450 = 92791./100000;
nmax_450 = 94330./100000;
nmin_475 = 94331./100000;
nmax_475 = 95670./100000;
nmin_500 = 95671./100000;
nmax_500 = 96840./100000;
nmin_525 = 96841./100000;
nmax_525 = 97850./100000;
nmin_550 = 97851./100000;
nmax_550 = 98710./100000;
nmin_575 = 98711./100000;
nmax_575 = 99420./100000;
nmin_600 = 99421./100000;
nmax_600 = 100000./100000;
x_photon = zeros(1,nhistories);
y_photon = zeros(1,nhistories);
z_photon = zeros(1,nhistories);
E_photon = zeros(1,nhistories);
gauss_r = a.*exp(-((r_circ - mu).^2)./(2.*(sig.^2)));
if n < nmin_050.*nhistories
elseif (n > nmax_025.*nhistories) && (n < nmin_075.*nhistories)
elseif (n > nmax_050.*nhistories) && (n < nmin_100.*nhistories)
elseif (n > nmax_075.*nhistories) && (n < nmin_125.*nhistories)
elseif (n > nmax_100.*nhistories) && (n < nmin_150.*nhistories)
elseif (n > nmax_125.*nhistories) && (n < nmin_175.*nhistories)
elseif (n > nmax_150.*nhistories) && (n < nmin_200.*nhistories)
elseif (n > nmax_175.*nhistories) && (n < nmin_225.*nhistories)
elseif (n > nmax_200.*nhistories) && (n < nmin_250.*nhistories)
elseif (n > nmax_225.*nhistories) && (n < nmin_275.*nhistories)
elseif (n > nmax_250.*nhistories) && (n < nmin_300.*nhistories)
elseif (n > nmax_275.*nhistories) && (n < nmin_325.*nhistories)
elseif (n > nmax_300.*nhistories) && (n < nmin_350.*nhistories)
elseif (n > nmax_325.*nhistories) && (n < nmin_375.*nhistories)
elseif (n > nmax_350.*nhistories) && (n < nmin_400.*nhistories)
elseif (n > nmax_375.*nhistories) && (n < nmin_425.*nhistories)
elseif (n > nmax_400.*nhistories) && (n < nmin_450.*nhistories)
elseif (n > nmax_425.*nhistories) && (n < nmin_475.*nhistories)
elseif (n > nmax_450.*nhistories) && (n < nmin_500.*nhistories)
elseif (n > nmax_475.*nhistories) && (n < nmin_525.*nhistories)
elseif (n > nmax_500.*nhistories) && (n < nmin_550.*nhistories)
elseif (n > nmax_525.*nhistories) && (n < nmin_575.*nhistories)
elseif (n > nmax_550.*nhistories) && (n < nmin_600.*nhistories)
[~,idx]=min(abs(gauss_r - E_photon(j)));
x_frac = randi([0, 4294967296])/4294967296.0;
x_photon(j) = pmx.*x_frac.*abs(r_circ(idx));
y_photon(j) = pmy.*sqrt((r_circ(idx)).^2 - (x_photon(j)).^2);
scatter3(x_photon,y_photon,z_photon)