* phi_scan.kumac - scan the beam centroid offset across the face
*                  of the collimator and map out how a beam property
*                  like net intensity or average polarization depends
*                  on beam position.
macro make id=10 idin=100 idcrop=990 thetamax=0.5 Emax=12 dist=75
  v/del vfr*
  v/cre vfr(10,10)
  do i=1,10
    t=$sigma([thetamax]*([i]-5.5)/10)
    do j=1,10
      p=$sigma(3.1416*([j]-0.5)/10)
      x0=$sigma(([t])*0.511e-3/[Emax]*[dist]*cos([p]))
      y0=$sigma(([t])*0.511e-3/[Emax]*[dist]*sin([p]))
      h/del [idcrop]
      exec phi_crop#make id=[idcrop] x0=[x0] y0=[y0] opt=' '
      exec phi_crop#sum id=[idin] idcrop=[idcrop] verbose=0
      sigma hintpl=hinteg
      h/del [idcrop]
      exec phi_crop#make id=[idcrop] x0=[x0] y0=$sigma(-([y0])) opt=' '
      exec phi_crop#sum id=[idin] idcrop=[idcrop] verbose=0
      v/inp vfr([i],[j]) $sigma((hinteg+hintpl)/2)
      message vfr([i],[j]) is $sigma((hinteg+hintpl)/2)
    enddo
  enddo
  2dhist [id] '' 10 0 [thetamax] 10 0 3.1416
  put/con [id] vfr
return