diff --git a/.gitignore b/.gitignore
index 9719c91..9dcb86b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -12,6 +12,7 @@ pxi-time-order
 evt2root
 evt2hist
 ev22txt
+EventBuilder
 
 *.so
 *.d
diff --git a/Monitor_raw.C b/Monitor_raw.C
index cede9ba..34ebf03 100644
--- a/Monitor_raw.C
+++ b/Monitor_raw.C
@@ -1,31 +1,31 @@
 #define Monitor_raw_cxx
 
-#include "Monitor_raw.h"
+
 #include <TH2.h>
 #include <TH1.h>
 #include <TStyle.h>
+
 #include <TCanvas.h>
 #include <TMath.h>
 #include <vector>
-#include <TStopwatch.h>
+
 
 //############################################ User setting
 
 int rawEnergyRange[2] = {500,  6000}; // in ch, {min, max}
-int    energyRange[3] = {2, 40,  2000}; // in keV, {resol, min, max}
+int    energyRange[3] = {1, 40,  2000}; // in keV, {resol, min, max}
 
 TString e_corr = "correction_e.dat";
 
 Long64_t maxEvent = -1;
 
+bool isBuildEventRoot = true; // is true, no histogram
+
+
 //############################################ end of user setting
 
-ULong64_t NumEntries = 0;
-ULong64_t ProcessedEntries = 0;
-Float_t Frac = 0.1; ///Progress bar
-TStopwatch StpWatch;
+#include "Monitor_raw.h"
 
-vector<vector<double>> eCorr;
 
 //############################################ histogram declaration
 
@@ -37,39 +37,50 @@ TH2F * heCalvID;
 //############################################ BEGIN
 void Monitor_raw::Begin(TTree * tree){
    TString option = GetOption();
-   
-   NumEntries = tree->GetEntries();
-   
-   printf("======================== Creating histograms\n");
 
-   for( int i = 0 ; i < NCRYSTAL ; i++){
-      he[i]    = new TH1F (Form("he%02d", i),            Form("e%02d", i),            rawEnergyRange[1]-rawEnergyRange[0], rawEnergyRange[0], rawEnergyRange[1]);  
-      heCal[i] = new TH1F (Form("heCal%02d", i), Form("e%02d (Cali.)", i), (energyRange[2]-energyRange[1])/energyRange[0],    energyRange[1],    energyRange[2]);  
+   totnumEntry = tree->GetEntries();
+
+   printf( "=========================================================================== \n");
+   printf( "========================== Monitor_raw.C/h ================================ \n");
+   printf( "======  total Entry : %lld \n", totnumEntry);
+   printf( "=========================================================================== \n");
+   
+   
+   if( isBuildEvent == false && isBuildEventRoot == false) {
+      printf("======================== Creating histograms\n");
+
+      for( int i = 0 ; i < NCRYSTAL ; i++){
+         he[i]    = new TH1F (Form("he%02d", i),            Form("e%02d", i),            rawEnergyRange[1]-rawEnergyRange[0], rawEnergyRange[0], rawEnergyRange[1]);  
+         heCal[i] = new TH1F (Form("heCal%02d", i), Form("e%02d (Cali.)", i), (energyRange[2]-energyRange[1])/energyRange[0],    energyRange[1],    energyRange[2]);  
+         
+         switch (i%4){
+            case 0: he[i]->SetLineColor(2);break;
+            case 1: he[i]->SetLineColor(kYellow+3);break;
+            case 2: he[i]->SetLineColor(kGreen+2);break;
+            case 3: he[i]->SetLineColor(4);break;
+         }
+         switch (i%4){
+            case 0: heCal[i]->SetLineColor(2);break;
+            case 1: heCal[i]->SetLineColor(kYellow+3);break;
+            case 2: heCal[i]->SetLineColor(kGreen+2);break;
+            case 3: heCal[i]->SetLineColor(4);break;
+         }
+      }
       
-      switch (i%4){
-         case 0: he[i]->SetLineColor(2);break;
-         case 1: he[i]->SetLineColor(kYellow+3);break;
-         case 2: he[i]->SetLineColor(kGreen+2);break;
-         case 3: he[i]->SetLineColor(4);break;
-      }
-      switch (i%4){
-         case 0: heCal[i]->SetLineColor(2);break;
-         case 1: heCal[i]->SetLineColor(kYellow+3);break;
-         case 2: heCal[i]->SetLineColor(kGreen+2);break;
-         case 3: heCal[i]->SetLineColor(4);break;
-      }
-   }
-   
-   heCalvID = new TH2F("heCalvID", "ID vs Energy (Cali.); ID; Energy",   NCRYSTAL, 0, NCRYSTAL, (energyRange[2]-energyRange[1])/energyRange[0],    energyRange[1],    energyRange[2]);
+      heCalvID = new TH2F("heCalvID", "ID vs Energy (Cali.); ID; Energy",   NCRYSTAL, 0, NCRYSTAL, (energyRange[2]-energyRange[1])/energyRange[0],    energyRange[1],    energyRange[2]);
 
-   
-   printf("======================== end of histograms creation.\n");
+      
+      printf("------------------------ end of histograms creation.\n");
+   }
    
    printf("======================== Load parameters.\n");
    eCorr = LoadCorrectionParameters(e_corr); 
    
-   StpWatch.Start();
-   printf("======================== Start processing....\n");
+   time0 = 0;
+   timeDiff = 0;
+   
+   ClearTreeData();
+   
    
 }
 
@@ -79,11 +90,11 @@ Bool_t Monitor_raw::Process(Long64_t entry){
    ProcessedEntries++;
    
    /*********** Progress Bar ******************************************/ 
-   if (ProcessedEntries>NumEntries*Frac-1) {
-      TString msg; msg.Form("%llu", NumEntries/1000);
+   if (ProcessedEntries>totnumEntry*Frac-1) {
+      TString msg; msg.Form("%llu", totnumEntry/1000);
       int len = msg.Sizeof();
       printf(" %3.0f%% (%*llu/%llu k) processed in %6.1f sec | expect %6.1f sec\n",
-               Frac*100, len, ProcessedEntries/1000,NumEntries/1000,StpWatch.RealTime(), StpWatch.RealTime()/Frac);
+               Frac*100, len, ProcessedEntries/1000,totnumEntry/1000,StpWatch.RealTime(), StpWatch.RealTime()/Frac);
       StpWatch.Start(kFALSE);
       Frac+=0.1;
    }
@@ -93,22 +104,25 @@ Bool_t Monitor_raw::Process(Long64_t entry){
       Terminate();
    }
    
+   if( isBuildEventRoot || isBuildEvent ) entry = index[entry];
+   
    b_ID->GetEntry(entry);
    b_energy->GetEntry(entry);
-   b_timestamp->GetEntry(entry);
+   b_energy_timestamp->GetEntry(entry);
    
-   int detID = mapping[ID];
-   
-   if( 0 <= detID && detID < 100 ){
-      he[detID]->Fill(e);
-      
-      //double eCal = ApplyCorrection(eCorr, detID, e);
-      double eCal = eCorr[detID][0]+eCorr[detID][1]*e;
-      heCal[detID]->Fill(eCal);
-      
-      heCalvID->Fill(detID, eCal);
+   if ( isBuildEventRoot || isBuildEvent ) {
+      BuildEvent();
+   }else{
+      if( detID < 100 ){
+         he[detID]->Fill(energy);
+         
+         ///double eCal = ApplyCorrection(eCorr, detID, e); //slow, why?
+         double eCal = eCorr[detID][0] + eCorr[detID][1]*energy;
+         heCal[detID]->Fill(eCal);
+         
+         heCalvID->Fill(detID, eCal);
+      }
    }
-   
 
    return kTRUE;
 }
@@ -116,38 +130,47 @@ Bool_t Monitor_raw::Process(Long64_t entry){
 //############################################ TERMINATE
 void Monitor_raw::Terminate(){
    
-   printf("============================== finishing.\n");
+   
+   printf("============================== finished.\n");
    gROOT->cd();
    
-   int nCrystalPerClover = 4;
-   int nClover = NCRYSTAL / nCrystalPerClover;
-
-   TCanvas * cc = new TCanvas("cc", "cc", 2000, 2000);
-   if( cc->GetShowEventStatus() == 0 ) cc->ToggleEventStatus();
-   cc->Divide(1, 9, 0);
+   if ( isBuildEventRoot || isBuildEvent ) {
+      saveFile->cd();
+      newtree->Write();
+      saveFile->Close();
+   }else{
    
-    for (Int_t i = 0; i < nClover; i++) {
-      int canvasID =  i + 1;
-      cc->cd(canvasID); 
-      cc->cd(canvasID)->SetGrid();       
-      cc->cd(canvasID)->SetTickx(2);   
-      cc->cd(canvasID)->SetTicky(2);   
-      cc->cd(canvasID)->SetBottomMargin(0.06);
-      cc->cd(canvasID)->SetLogy();
+      int nCrystalPerClover = 4;
+      int nClover = NCRYSTAL / nCrystalPerClover;
 
-      for( Int_t j = 0; j < nCrystalPerClover; j++){
-         int hID = nCrystalPerClover*i+ j ;
-         heCal[hID]->Draw("same");         
-         //he[hID]->Draw("same");         
+      TCanvas * cc = new TCanvas("cc", "cc", 2000, 2000);
+      if( cc->GetShowEventStatus() == 0 ) cc->ToggleEventStatus();
+      cc->Divide(1, 9, 0);
+      
+       for (Int_t i = 0; i < nClover; i++) {
+         int canvasID =  i + 1;
+         cc->cd(canvasID); 
+         cc->cd(canvasID)->SetGrid();       
+         cc->cd(canvasID)->SetTickx(2);   
+         cc->cd(canvasID)->SetTicky(2);   
+         cc->cd(canvasID)->SetBottomMargin(0.06);
+         cc->cd(canvasID)->SetLogy();
+
+         for( Int_t j = 0; j < nCrystalPerClover; j++){
+            int hID = nCrystalPerClover*i+ j ;
+            heCal[hID]->Draw("same");         
+            //he[hID]->Draw("same");         
+         }
       }
+      cc->SetCrosshair(1);
+      
+      TCanvas * c1 = new TCanvas("c1", "c1", 1000, 1000);
+      if( c1->GetShowEventStatus() == 0 ) c1->ToggleEventStatus();
+      c1->SetLogz();
+      c1->SetGridx();
+      heCalvID->SetNdivisions(-409, "X");
+      heCalvID->Draw("colz");
+      
    }
-   cc->SetCrosshair(1);
-   
-   TCanvas * c1 = new TCanvas("c1", "c1", 1000, 1000);
-   if( c1->GetShowEventStatus() == 0 ) c1->ToggleEventStatus();
-   c1->SetLogz();
-   c1->SetGridx();
-   heCalvID->SetNdivisions(-409, "X");
-   heCalvID->Draw("colz");
    
 }
diff --git a/Monitor_raw.h b/Monitor_raw.h
index 9bac8a4..46cc0c6 100644
--- a/Monitor_raw.h
+++ b/Monitor_raw.h
@@ -3,8 +3,12 @@
 
 #include <TROOT.h>
 #include <TChain.h>
+#include <TTree.h>
 #include <TFile.h>
+#include <TMacro.h>
 #include <TSelector.h>
+#include <TStopwatch.h>
+#include <TTreeIndex.h>
 
 #include "mapping.h"
 #include "armory/AnalysisLibrary.h"
@@ -19,17 +23,20 @@ public :
 
    // Declaration of leaf types
    Long64_t        evID;
-   UShort_t        ID;
-   UShort_t        e;
-   ULong64_t       t;
+   UShort_t        detID;
+   UShort_t        energy;
+   ULong64_t       energy_t;
 
    // List of branches
    TBranch        *b_data_ID;   //!
    TBranch        *b_ID;   //!
    TBranch        *b_energy;   //!
-   TBranch        *b_timestamp;   //!
+   TBranch        *b_energy_timestamp;   //!
 
-   Monitor_raw(TTree * /*tree*/ =0) : fChain(0) { }
+   Monitor_raw(TTree * /*tree*/ =0) : fChain(0) { isBuildEvent = false; 
+                                                  timeWindow = 100;
+                                                  saveFileName = "test.root";
+                                                }
    virtual ~Monitor_raw() { }
    virtual Int_t   Version() const { return 2; }
    virtual void    Begin(TTree *tree);
@@ -44,8 +51,44 @@ public :
    virtual TList  *GetOutputList() const { return fOutput; }
    virtual void    SlaveTerminate();
    virtual void    Terminate();
+   
+   void SetBuildEvent(bool buildOption = false){ isBuildEvent = buildOption;}
 
    ClassDef(Monitor_raw,0);
+   
+   //=================== progress
+   ULong64_t ProcessedEntries = 0;
+   Float_t Frac = 0.1; ///Progress bar
+   TStopwatch StpWatch;
+   
+   //=================== correction parameters
+   vector<vector<double>> eCorr;
+   
+   //=================== output tree;   
+   bool isBuildEvent;
+   int timeWindow;
+   ULong64_t time0;  //time-0 for each event
+   int       timeDiff; 
+   Long64_t * index;  //!
+
+   TFile * saveFile; //!
+   TTree * newtree; //!
+   TString saveFileName;
+   Long64_t totnumEntry; /// of original root
+   
+   //tree  
+   void ClearTreeData();
+   void BuildEvent();
+   
+   Int_t eventID;
+   double       e[NCRYSTAL];
+   ULong64_t   e_t[NCRYSTAL];
+   double    bgo[NBGO];
+   ULong64_t bgo_t[NBGO];
+   Short_t   other[NOTHER];
+   Short_t  multi;
+   
+   
 };
 
 #endif
@@ -55,15 +98,187 @@ void Monitor_raw::Init(TTree *tree)
 {
    // Set branch addresses and branch pointers
    if (!tree) return;
-   fChain = tree;
+   
+   fChain = (TChain *) tree;
    fChain->SetMakeClass(1);
 
-   fChain->SetBranchAddress("evID", &evID, &b_data_ID);
-   fChain->SetBranchAddress("id",     &ID, &b_ID);
-   fChain->SetBranchAddress("e",       &e, &b_energy);
-   fChain->SetBranchAddress("t",       &t, &b_timestamp);
+   fChain->SetBranchAddress("evID",    &evID, &b_data_ID);
+   fChain->SetBranchAddress("id",     &detID, &b_ID);
+   fChain->SetBranchAddress("e",     &energy, &b_energy);
+   fChain->SetBranchAddress("e_t", &energy_t, &b_energy_timestamp);
+   
+   if( isBuildEventRoot || isBuildEvent){
+   
+      printf("======================== Buidling Index using the timestamp\n");
+      tree->BuildIndex("e_t");
+      TTreeIndex *in = (TTreeIndex*) tree->GetTreeIndex(); 
+      index = in->GetIndex();     
+      
+      //for(int i = 0; i < 100; i++){
+      //   printf(" %3d | %lld \n", i, index[i]);
+      //} 
+      
+      
+      TString option = GetOption();
+      
+      //printf("======================== Formation of output file name\n");
+      //int numFile = fChain->GetListOfFiles()->GetLast() + 1;   //need input of TChain
+      //
+      //printf(".......... number of files : %d \n", numFile);
+      //
+      //if( numFile > 0 ) {
+      //   int oldRunNum = -100;
+      //   bool contFlag = false; // is runNumber continue;
+      //   for( int i = 0; i < numFile ; i++){
+      //      TString name = ((TChain *) fChain)->GetListOfFiles()->At(i)->GetTitle();
+      //      int found = name.Last('/');
+      //      name.Remove(0, found + 1 ); // this should give "XXX_run0XX.root"
+      //      TString prefix = name;
+      //      found = name.Last('.');
+      //      name.Remove(found); // this should give "XXX_run0XX"
+      //      found = name.Last('_');
+      //      int runNum = name.Remove(0, found+4).Atoi(); // this should give the 3 digit run number 
+      //
+      //      if( i == 0 ) {
+      //         found = prefix.First("_");
+      //         prefix.Remove(found);
+      //         saveFileName = prefix +  "_run";
+      //      }
+      //
+      //      if( runNum == oldRunNum + 1 ){
+      //         int kk = saveFileName.Sizeof();
+      //         if( contFlag == false ){
+      //            saveFileName.Remove(kk-2); //remove the "-"
+      //            saveFileName += "-";
+      //         }else{
+      //            saveFileName.Remove(kk-5); //remove the runNum and "-"
+      //         }
+      //         contFlag = true;
+      //      }
+      //      if( runNum > oldRunNum + 1) contFlag = false;
+      //      
+      //      saveFileName += Form("%03d_", runNum);
+      //      oldRunNum = runNum;
+      //   }
+      //   int kk = saveFileName.Sizeof();
+      //   saveFileName.Remove(kk-2); // remove the last "-"
+      //   saveFileName += ".root";
+      //}else{
+      //   gROOT->ProcessLine(".q");
+      //}
+      
+      if( option != "" ) saveFileName = option;
+      
+      printf("save file name : %s \n", saveFileName.Data());
+      printf("---------------------------------------------\n");
+            
+      //TODO;
+      saveFile = new TFile(saveFileName, "recreate");
+      saveFile->cd();
+      newtree = new TTree("tree", "tree");
+
+      printf("======================== Create output tree\n");
+      
+      newtree->Branch("evID", &eventID, "event_ID/l"); 
+      newtree->Branch("e",         e, Form("e[%d]/D", NCRYSTAL));
+      newtree->Branch("e_t",     e_t, Form("e_timestamp[%d]/l", NCRYSTAL));
+      //newtree->Branch("p",    pileup, Form("pile_up_flag[%d]/s", NCRYSTAL));
+      //newtree->Branch("hit",     hit, Form("hit[%d]/s", NCRYSTAL));
+
+      newtree->Branch("bgo",     bgo, Form("BGO_e[%d]/D", NBGO));
+      newtree->Branch("bgo_t", bgo_t, Form("BGO_timestamp[%d]/l", NBGO));
+
+      newtree->Branch("other", other, Form("other_e[%d]/D", NOTHER));
+
+      newtree->Branch("multi", &multi, "multiplicity_crystal/I");
+      
+      
+      if( eCorr.size() > 0 ) {
+         TMacro energyCorr(e_corr);
+         energyCorr.Write("energyCorr");
+      }
+      
+   }
+   
+   
+   printf("======================== Start processing....\n");
+   StpWatch.Start();
+   eventID = 0;
+      
 }
 
+
+void Monitor_raw::ClearTreeData(){
+   
+   for( int i = 0; i < NCRYSTAL; i++){
+      e[i]      = TMath::QuietNaN();
+      e_t[i]    = 0;
+      //pileup[i] = 0;
+      //hit[i]    = 0;
+   }
+   for( int i = 0; i < NBGO; i++) {
+      bgo[i]   = TMath::QuietNaN();
+      bgo_t[i] = 0 ;
+   }
+   for( int i = 0; i < NOTHER; i++) {
+      other[i] = TMath::QuietNaN(); 
+   }
+   multi = 0;
+}
+
+void Monitor_raw::BuildEvent(){
+
+   if( time0 == 0) time0 = energy_t;
+   
+   timeDiff = (int) (energy_t - time0);
+   
+   if( timeDiff < timeWindow ) {
+      
+      if ( detID < NCRYSTAL ){
+         e[detID] = energy;
+         e_t[detID] = energy_t;
+         multi++;
+      }
+      if ( 100 <= detID && detID < 100 + NBGO ){
+         bgo[detID-100]   = energy;
+      bgo_t[detID-100] = energy_t;
+      }
+      if ( 200 <= detID && detID < 200 + NOTHER){
+         other[detID-200] = energy;
+      }
+      
+      //printf("%d | %3d   %6d  %10llu, %3d\n", multi, detID, energy, energy_t, timeDiff);
+      
+   }else{
+      //---- end of event
+      eventID ++;
+
+      saveFile->cd();
+      newtree->Fill();
+      
+      ClearTreeData();
+      
+      /// fill 1st data of an event                  
+      time0 = energy_t;
+      timeDiff = 0;
+      
+      if ( detID < NCRYSTAL ){
+         e[detID] = energy;
+         e_t[detID] = energy_t;
+         multi = 1;
+      }
+      if ( 100 <= detID && detID < 100 + NBGO ){
+         bgo[detID-100]   = energy;
+      bgo_t[detID-100] = energy_t;
+      }
+      if ( 200 <= detID && detID < 200 + NOTHER){
+         other[detID-200] = energy;
+      }
+      
+   }
+}
+
+
 Bool_t Monitor_raw::Notify()
 {
    return kTRUE;