void MUONdigit (Int_t evNumber1=0,Int_t evNumber2=0,Int_t nCathode=1) 
{
/////////////////////////////////////////////////////////////////////////
//                                                                     //
//   This macros converts the pad-hit information into digits          //
//                                                                     //
/////////////////////////////////////////////////////////////////////////

// Dynamically link some shared libs

   if (gClassTable->GetID("AliRun") < 0) {
       gSystem->Load("$ALITOP/cern.so/lib/libpdfDUMMY.so");
       gSystem->Load("$ALITOP/cern.so/lib/libPythia.so");
       gSystem->Load("$ROOTSYS/lib/libEG.so");       
       gSystem->Load("$ROOTSYS/lib/libEGPythia.so");    
       gSystem->Load("libGeant3Dummy.so");        //a dummy version of Geant3
       gSystem->Load("PHOS/libPHOSdummy.so");     //the standard Alice classes 
       gSystem->Load("libgalice.so");             //the standard Alice classes 
   }

// Connect the Root Galice file containing Geometry, Kine and Hits

   TFile *file = (TFile*)gROOT->GetListOfFiles()->FindObject("galice.root");
   if (file) file->Close(); 
   file = new TFile("galice.root","UPDATE");
   file->ls();
//   file->Map();

   printf ("\n File loaded !");

// Get AliRun object from file or create it if not on file

   if (!gAlice) {
       gAlice = (AliRun*)file->Get("gAlice");
       if (gAlice) printf("\n AliRun object found on file\n");
       if (!gAlice) gAlice = new AliRun("gAlice","Alice test program");
   }
   printf ("\n gAlice created !\n");

   AliMUON *MUON  = gAlice->GetDetector("MUON");

   AliMUONchamber*  iChamber;
   AliMUONsegmentation*  segmentation;

   Int_t Npx[10];
   Int_t Npy[10];

   Int_t nxmax=1026;
   Int_t nymax=1026;
   AliMUONlist *elem[10][1026][1026];
   TObjArray *obj=new TObjArray;

   Int_t trk[500];
   Int_t chtrk[500];


   Int_t digits[3]; 
   TVector *trinfo;
   trinfo=new TVector(2);

//
//   Loop over events 
//

   Int_t Nh=0;
   Int_t Nh1=0;
   for (int nev=0; nev<= evNumber2; nev++) {
       Int_t nparticles = gAlice->GetEvent(nev);
       cout << "nev         " <<nev<<endl;
       cout << "nparticles  " <<nparticles<<endl;
       if (nev < evNumber1) continue;
       if (nparticles <= 0) return;

       TTree *TH = gAlice->TreeH();
       Int_t ntracks = TH->GetEntries();
       Int_t Nc=0;

       Int_t counter=0;
       //
       // loop over cathodes
       for (int icat=0; icat<nCathode; icat++) { 
	   //
	   // initialize the array of pointers 
	   printf("\n Initialize array of pointers \n");
	   for (int i=0; i<10; i++) {
	       for (int j=0; j<nymax; j++) {
		   for (int k=0; k<nxmax; k++) {	
		       elem[i][j][k]=0;
		   }
	       }
	   }
	   printf("\n Finished !\n");
     
//
//   Loop over tracks
//
	   printf("\n ntracks: %d",ntracks);
	   
	   for (Int_t track=0; track<ntracks;track++) {
	       gAlice->ResetHits();
	       Int_t nbytes += TH->GetEvent(track);
	       if (MUON)  {
		   for(AliMUONhit* mHit=(AliMUONhit*)MUON->FirstHit(-1); 
		       mHit;
		       mHit=(AliMUONhit*)MUON->NextHit()) 
		   {
		       Int_t   nch   = mHit->fChamber;  // chamber number
		       Float_t x     = mHit->fX;        // x-pos of hit
		       Float_t y     = mHit->fY;        // y-pos
		       

		       iChamber = &(MUON->Chamber(nch-1));
		       response=iChamber->GetResponseModel();
		       
		       Int_t nsec=iChamber->Nsec();
		       Int_t rmin = (Int_t)iChamber->frMin;
		       Int_t rmax = (Int_t)iChamber->frMax;
		       if (nch > 10) continue;
		       
//
//
		       for (AliMUONcluster* mPad=
				(AliMUONcluster*)MUON->FirstPad(mHit);
			    mPad;
			    mPad=(AliMUONcluster*)MUON->NextPad())
		       {
			   Int_t cathode  = mPad->fCathode;   // cathode number
			   Int_t nhit     = mPad->fHitNumber; // hit number
			   Int_t qtot     = mPad->fQ;         // charge
			   Int_t ipx      = mPad->fPadX;      // pad  X
			   Int_t ipy      = mPad->fPadY;      // pad  Y
			   Int_t iqpad    = mPad->fQpad;      // charge per pad
			   Int_t rsec     = mPad->fRSec;      // sector#
//
//
			   if (cathode != (icat+1)) continue;
			   segmentation=iChamber-> 
			       GetSegmentationModel(cathode);
			   Int_t Npx[nch-1]  = segmentation->Npx();
			   Int_t Npy[nch-1]  = segmentation->Npy();
			   
			   
			   Int_t npx=Npx[nch-1];
			   Int_t npy=Npy[nch-1];
			   Float_t thex, they;
			   segmentation->GetPadCxy(ipx,ipy,thex,they);
			   
			   Float_t rpad=TMath::Sqrt(thex*thex+they*they);
			   
			   
                	// check boundaries
			   if (rpad < rmin || iqpad ==0 || rpad > rmax) continue;

			   // fill the info array

			   trinfo(0)=(Float_t)track;
			   trinfo(1)=(Float_t)iqpad;

			   digits[0]=ipx;
			   digits[1]=ipy;
			   digits[2]=iqpad;

			   // build the list of fired pads and update the info
			   
			   AliMUONlist *pdigit=elem[nch-1][ipy+npy][ipx+npx];

			   if (pdigit==0) {
			       obj->AddAtAndExpand(
				   new AliMUONlist(rpad,digits),counter);
			       counter++;
			       Int_t last=obj->GetLast();
			       pdigit=(AliMUONlist*)obj->At(last);
			       elem[nch-1][ipy+npy][ipx+npx]=pdigit;
			       // list of tracks
			       TObjArray *trlist=
				   (TObjArray*)pdigit->TrackList();
			       trlist->Add(trinfo);
			   } else {
			       // update charge
			       (*pdigit).fSignal+=iqpad;
			       // update list of tracks
			       TObjArray* trlist=(TObjArray*)pdigit
				   ->TrackList();
			       Int_t nptracks=trlist->GetEntriesFast();
			       
			       for (Int_t tr=0;tr<nptracks;tr++) {
				   TVector *ptrk=(TVector*)trlist->At(tr);
//				   TVector &vtrk = *ptrk;
				   Int_t entries=ptrk->GetNrows();
				   trk[tr]=Int_t(ptrk(0));
				   chtrk[tr]=Int_t(ptrk(1));
				   if (trk[tr]==track) {
				       chtrk[tr]+=iqpad;
				       trlist->RemoveAt(tr);
				       trinfo(0)=trk[tr];
				       trinfo(1)=chtrk[tr];
				       trlist->AddAt(trinfo,tr);
				   } else {
				       trlist->Add(trinfo);
				   }
			       } // end loop over list of tracks for one pad
			   } // end if pdigit
		       } //end loop over clust
		   } // hit loop
	       } // if MUON
	   } // track loop

	   Int_t tracks[10];
	   Int_t charges[10];
	   cout<<"Start filling digits now !"<<endl;
	   const Int_t zero_supm = 6;
	   const Int_t adc_satm = 1024;
	   Int_t nd=0;
	   

	   // start filling the digits
	   for (Int_t id=0; id<10; id++) {
	       Int_t nd=0;
	       for (Int_t iy=0;iy<nymax;iy++) {
		   for (Int_t ix=0;ix<nxmax;ix++) {
		       AliMUONlist *address=elem[id][iy][ix];
		       if (address==0) continue; 
		       // do zero-suppression and signal truncation
		       Int_t q=address->fSignal;        
		       // 
		       if ( q <= zero_supm ) continue;
		       if ( q > adc_satm)  q=adc_satm;
		       digits[0]=address->fPadX;
		       digits[1]=address->fPadY;
		       digits[2]=address->fSignal;

		       TObjArray* trlist=(TObjArray*)address->TrackList();
		       Int_t nptracks=trlist->GetEntriesFast();
		       // this was changed to accomodate the real number of tracks
		       if (nptracks > 10) {
			   cout<<"Attention - nptracks > 10 "<<nptracks<<endl;
			   nptracks=10;
		       }
		       for (Int_t tr=0;tr<nptracks;tr++) {
			   TVector *pp=(TVector*)trlist->At(tr);
			   Int_t entries=pp->GetNrows();
			   TVector &v2 = *pp;
			   tracks[tr]=(Int_t)v2(0);
			   charges[tr]=(Int_t)v2(1);
		       } //end loop over list of tracks for one pad

		       // fill digits
		       MUON->AddDigits(id,tracks,charges,digits);
		       nd++;
		   } // end loop over ix
	       } // end loop over iy
	       cout<<"I'm out of the loops over pads"<<endl;
	       cout<<" id  nd  "<<id<<" "<<nd<<endl;
	   } //loop over chambers
	   cout<<"I'm out of the loops for digitisation"<<endl;

	   gAlice->TreeD()->Fill();
	   TTree *TD=gAlice->TreeD();
	   int ndig=TD->GetEntries();
	   cout<<"number of digits  "<<ndig<<endl;

	   TClonesArray *fDch;
	   for (int i=0;i<10;i++) {
	       fDch= MUON->DigitsAddress(i);
	       int ndig=fDch->GetEntriesFast();
	       printf (" i, ndig %d %d \n",i,ndig);
	   }


	   MUON->ResetDigits();
	   obj->Clear();
       } //end loop over cathodes

       char hname[30];
       sprintf(hname,"TreeD%d",nev);
       gAlice->TreeD()->Write(hname);
       
       file->ls();
//       file->Map();
   } // event loop 
   obj->Delete();
   delete obj;

   file->Close();
   cout<<"END  digitisation "<<endl;
   
}