subroutine write_single_particle_by_element(i, ele_name, coord, s_frac,s_tot, Q) 

        use bmad
        use parameters_bmad
        implicit none
        type(coord_struct) coord
        integer i
        integer, save :: lun29
        real(rp) s_frac, s_tot  ! fractional turn, total turns
        real(rp) Q(3)
        logical first/.true./
        character*16 ele_name

        if(first)then
         lun29 = lunget()
         open(unit=lun29, file = trim(directory)//'/'//'single_particle_by_element.dat')
         first=.false.
         write(lun29,'(a10,1x,a16,9a14,2a10,1x,12x,a12,12x)')' turn ','Element','x','xp','y','yp','z','pz','t','s','s total','state','muon','polarization'
        endif
        write(lun29,'(i10,1x,a16,1x,9es14.6,i10,1x,3es12.4)')i,ele_name,coord%vec, coord%t, s_frac, s_tot, coord%state, Q
        return
        end