Double_t tpileup_prompt(Double_t *t, Double_t *par) // prompt proton/gamma pdf
 { 
   double yield = 0.;
   double pg_start = -69.70; // opening of PiGate
   double pg_close = 222.50; // closing of PiGate
   double T = 19.75;         // rf Period, ns
   double sigma = 1.;        // TDC resolution, ns

   if ( t[0] > pg_start && t[0] < pg_close ) {
     for (int n= -3; n< 11; n++ ) {
         if ( n==0 && fabs(-t[0] + n*T)<3*sigma ) 
         yield+ = par[1]*exp( -0.5*(-t[0] + n*T)*(-t[0] + n*T)/(sigma*sigma) );        // prompt prob
         if ( n!=0 && fabs(-t[0] + n*T)<3*sigma ) 
         yield+ = exp( -0.5*(-t[0] + n*T)*(-t[0] + n*T)/(sigma*sigma) ); // prompt prob*pileup prob
     } // end for
     return par[0]*yield; } // end if
   else 
     return yield;
}