subroutine calc_bunch_params_cutoff (bunch, bunch_params, twiss, emitx_cutoff, error)
  use bmad
  use beam_mod
  implicit none

  !

  type (bunch_struct) bunch, bunch_temp
  type (bunch_params_struct)  bunch_params
  type (twiss_struct) twiss
  
  real(rp) emitx_cutoff
  real(rp) x, xp, x_action

  logical error

  integer n_part, i

  bunch_temp = bunch
  
  n_part = size(bunch%particle)

  do i = 1, n_part
     if (bunch%particle(i)%state /= alive$) cycle
     x = bunch%particle(i)%vec(1) - twiss%eta * bunch%particle(i)%vec(6)
     xp = bunch%particle(i)%vec(2)- twiss%etap * bunch%particle(i)%vec(6)
     x_action = twiss%gamma*x**2 + 2*twiss%alpha*x*xp + twiss%beta*xp**2
     if (x_action > emitx_cutoff) then
        bunch_temp%particle(i)%state = lost$
     end if
  end do
  call calc_bunch_params(bunch_temp, bunch_params, error, .true.)

end subroutine calc_bunch_params_cutoff