subroutine write_BetaCrossE_turn(n, co, sumBetaCrossE, muons, BetaCrossE_start_time)

        use bmad
        use parameters_bmad
        use muon_mod
        
        implicit none
        type (coord_struct) co
        type (sumbetaCrossE_struct) sumBetaCrossE
        type (muon_struct) muons
        integer, save :: lun
        real(rp) sum_vec(3), sum_vec_pitch(3), path, pathx
        real(rp) sum_time
        real(rp) BetaCrossE_start_time
        integer n
        logical first/.true./

        if(first)then
         lun = lunget()
         open(unit=lun, file = trim(directory)//'/'//'BetaCrossE_turn.dat')
         first=.false.
         write(lun,'(a10,1x,7a12,3a16,a16,3a16,a16,a16,3a16,3a16)')' turn ','x','xp','y','yp','z','pz','t','sumBetaCrossE-x','sumBetaCrossE-y','sumBetaCrossE-z', &
              'sum_time', 'sm(BetDotB)Bet-x','sm(BetDotB)Bet-y','sm(BetDotB)Bet-z','path',' (path)(x)' ,' B_field-x',' B_field-y',' B_field-z',&
                                      'BetaCrossB-x','BetaCrossB-y','BetaCrossB-z'
        endif
        write(lun,'(i10,1x,7es12.4,3es16.8, es16.8, 3es16.8, 2es16.8,3es16.8,3es16.8)')n,co%vec, co%t, muons%BetaCrossE(1:3), muons%BetaCrossE_time, muons%BetaDotB(1:3), &
                                                                           muons%path, muons%pathx, muons%B_field(1:3), muons%BetaCrossB(1:3)
        return
        end