#include<stdio.h>
#include<math.h>
float tlab2kcm(double tlab){
  //input: Kin enr pion in lab
  //output: kappa:com pion momentum 
  //  elpi=(ecm**2-mpi**2-mn**2)/(2mn)
  //solve for ecm**2
  float mn,mpi,kappa,ecm2,s;
  mpi=139.578;                       //pion mass
  mn=938.272*4.0;                    //nucleus mass he4
  ecm2=2.0*mn*(tlab+mpi)+mpi*mpi+mn*mn;
  s=ecm2;
  kappa = sqrt((s-(mn+mpi)*(mn+mpi))*(s-(mn-mpi)*(mn-mpi))/4./s);
  return kappa;
}
main()
{ //reads a table of pion mom. t in com and tot cross secti
  // for pi+ 4he total cross sections and produces
  // kcm**2 and tot cr sec
  float tpilab, totcross,kappa;
  int i;
  FILE *pf;
  pf=fopen("pi+he4tcs.dat","r");
  for(i=0;i<19;i++){
    fscanf(pf,"%f %f",&tpilab,&totcross);
    kappa=tlab2kcm(tpilab);
    printf("%f %f\n",tpilab,kappa*kappa*totcross);
  }
}