diff --git a/pre_simulation_TREPR.m b/pre_simulation_TREPR.m
index 58627ad..e2a9c4c 100644
--- a/pre_simulation_TREPR.m
+++ b/pre_simulation_TREPR.m
@@ -260,7 +260,9 @@ uiwait(fig)
         T1 = str2double(get(InpTx,'String'));
         T2 = str2double(get(InpTy,'String'));
         T3 = str2double(get(InpTz,'String'));
-        Exp.Temperature = [T1 T2 T3]; %Triplet population
+        Tsum = T1 + T2 + T3;
+        T1n = T1/Tsum; T2n = T2/Tsum; T3n = T3/Tsum; %normalize population
+        Exp.Temperature = [T1n T2n T3n]; %Triplet population
         Sys.S = str2double(get(InpS,'String')); % Total Spin
         Sys.g = str2double(get(InpG,'String')); % g-value
         D = str2double(get(InpD,'String'));
@@ -269,7 +271,14 @@ uiwait(fig)
         lwGau = str2double(get(InpGauss,'String'));
         lwLor = str2double(get(InpLor,'String'));
         Sys.lw = [lwGau lwLor]; % mT, linewidth needs to be optimised
-        
+        %perform a simulation with the parameters above
+        [bfield,spec] = pepper(Sys,Exp);
+        spec_norm = spec/max(spec); % normalize the simulation
+        %plot result
+        plot(ax,0.1*params.Field_Vector,params.max_mean,'r',...
+             bfield,spec_norm,'b','LineWidth',1.2)
+        legend('experimental','simulation')
+        axis tight
     end
 
     function PreSimDoneButtonPushed(src,event)