subroutine fpp_drift_dist(letime,toffset,iplane,dist)
c
c Written by Ed Brash
c
      implicit none
c
      include 'parameter.h'
      include 'espace_type.h'
      include 'detector.h'
      include 'transport.h'
      include 'option.h'
c
      real*8 letime,toffset,dist
      real*8 time
      integer iw,iplane

      time=toffset-letime

c this bit of code is for 85% Ar 15% CO2
c Uses the x-t relation of Mark Jones derived from a Garfield simulation
c
c      if(time.gt.2.0) then
c         dist = .01868 + .00518*time + .000015775*time**2 -
c     >        .00000018735*time**3
c      else
c         dist = .00860 + .01200*time - .001470*time**2
c      endif


c Below is the result for integral method (EJB)
c a single fit for all planes was used.
c
c      if(time.gt.0.0.and.time.le.110.0) then
c         dist=15.199-0.32085*time+2.9064*time**2-
c     >        .059774*time**3+.00054390*time**4-.0000018513*time**5
c         dist=dist*0.522/5350.0
c      else if ( time .le. 0 .and. time .gt. -10 ) then
c         dist = 0.0
c      else
c           dist=1.0
c      endif


c Below is the result for integral method (EJB/MKJ)
c an individual fit for each plane is used.
c

      if(time.gt.0.0.and.time.le.200.0) then
         dist=0
         do iw=1,6
            dist = dist + spdetector.l.fpp.plane(iplane).
     >           drift_dist_param(iw)*time**(iw-1) 
         enddo
         if(dist.gt.0.522) dist=0.522
         if (dist .lt. 0) dist = 0
      else if ( time .le. 0 .and. time .gt. -10 ) then
         dist = 0.0
      else
         dist=1.0
      endif

      return
      end