subroutine hec_beam_ini
c
c Initialize the procedure of MWPC alignment constants finding.
c Here the period dependent variables in the commons /config/ and
c /shifts/ can be changed. (see block data beam_data.f)
c
c If SHIFTX(ipla) or SHIFTY(ipla) is set greater then 1000., then
c the corresplonding x- or y-plane ipla will be rejected.
c
c The two reference chambers, which defines the coordinate system, 
c can be changed: NRFF and NRFL, by defauld these are the 2nd and 5th chambers.
c
c SHIFTX/Y(NRFF)=0.0 by defenition. The SHIFTX/Y(NRFL) should be choosen
c by such a way that the z_axis would be collinear to the beam direction
c (provided y_table=0.0) in some arbitrary (called further reference) run, 
c which belongs to the period of interest, and fixed to be used for all 
c the runs of this period. To find these values this program should be run 
c over the reference run data with SHIFTX/Y(NRFL) initially set to 0.0. The 
c needed values will be printed in the string:
c 'LAST REFERENCE MWPC DISPLACEMENTS: DX=... DY=...'
c These values should be assigned to SHIFTX/Y(NRFL) in THIS subroutine.
c
      implicit none
c
c common for datacard values
c
      include'hec_par.inc'       ! shared parameters
      include'hec_datacard.inc'
c
c common with MWPC alignment constants
c
      INCLUDE 'hec_beam_sys_cluset.inc'
      INCLUDE 'hec_beam_sys_clusters.inc'
      INCLUDE 'hec_beam_sys_config.inc'
      include 'hec_beam_sys_shifts.inc'
c
c local variables
c
c
      if (irunpd.eq.1) then		! may96
        SHIFTX(5)=2.236         ! ref. run #5261
        SHIFTY(5)=0.175         ! ref. run #5261
      elseif (irunpd.eq.2) then ! july96
        SHIFTX(1)=1001.         ! MWPC #1 was unoperable in july96
        SHIFTY(1)=1001.         ! MWPC #1 was unoperable in july96
        SHIFTY(4)=1001.         ! MWPC-y #4 was unoperable in july96
        SHIFTX(5)=1.524         ! ref. run #5573
        SHIFTY(5)=-0.056        ! ref. run #5573
      elseif (irunpd.eq.3) then ! sept96
        SHIFTX(1)=1001.         ! MWPC #1 was unoperable in sept96
        SHIFTY(1)=1001.         ! MWPC #1 was unoperable in sept96
        SHIFTX(5)=1.634         ! ref. run #6230
        SHIFTY(5)=0.390         ! ref. run #6230
      elseif (irunpd.eq.5) then ! may97
        print *,' '
        print *,' *** MWPCs were not working at this period: irunpd=5'
        print *,' '
      elseif (irunpd.eq.6 ) then ! oct97
        ZXPLANE(2)=180.          ! new position
        ZYPLANE(2)=ZXPLANE(2)-3. ! new position
        ZXPLANE(3)=279.          ! new position
        ZYPLANE(3)=ZXPLANE(3)-3. ! new position
        ZXPLANE(4)=351.          ! new position
        ZYPLANE(4)=ZXPLANE(4)-3. ! new position
        ZXPLANE(5)=3092.7        ! new position
        ZYPLANE(5)=ZXPLANE(5)-2.7 ! new position
        SHIFTX(1)=1001.          ! old MWPC #1 removed
        SHIFTY(1)=1001.          ! old MWPC #1 removed
        SHIFTX(5)=-0.494         ! ref. run #6699
        SHIFTY(5)=-0.476         ! ref. run #6699
      elseif (irunpd.eq.7 ) then ! April 98
        ZXPLANE(2)=180.          ! new position
        ZYPLANE(2)=ZXPLANE(2)-3. ! new position
        ZXPLANE(3)=279.          ! new position
        ZYPLANE(3)=ZXPLANE(3)-3. ! new position
        ZXPLANE(4)=351.          ! new position
        ZYPLANE(4)=ZXPLANE(4)-3. ! new position
        ZXPLANE(5)=3092.7        ! new position
        ZYPLANE(5)=ZXPLANE(5)-2.7 ! new position
        SHIFTX(1)=1001.         ! old MWPC #1 removed
        SHIFTY(1)=1001.         ! old MWPC #1 removed
        SHIFTX(5)=0.261         ! ref. run #7232
        SHIFTY(5)=-0.491        ! ref. run #7232
      elseif (irunpd .eq. 8) then ! August 98
        ZXPLANE(2)=180.         ! new position
        ZYPLANE(2)=ZXPLANE(2)-3.! new position
        ZXPLANE(3)=279.         ! new position
        ZYPLANE(3)=ZXPLANE(3)-3.! new position
        ZXPLANE(4)=351.         ! new position
        ZYPLANE(4)=ZXPLANE(4)-3.! new position
        ZXPLANE(5)=3092.7       ! new position
        ZYPLANE(5)=ZXPLANE(5)-2.7 ! new position
        SHIFTX(1)=1001.         ! old MWPC #1 removed
        SHIFTY(1)=1001.         ! old MWPC #1 removed
        SHIFTX(5)=0.343         ! ref. run #7979
        SHIFTY(5)=-1.105        ! ref. run #7979
      elseif (irunpd .ge. 9) then
c
c so far this is just a copy of August 1998 settings.
c
c        print *,'WARNING, we need new info in hec_beam_ini.f'
        ZXPLANE(2)=180.          ! new position
        ZYPLANE(2)=ZXPLANE(2)-3. ! new position
        ZXPLANE(3)=279.          ! new position
        ZYPLANE(3)=ZXPLANE(3)-3. ! new position
        ZXPLANE(4)=351.          ! new position
        ZYPLANE(4)=ZXPLANE(4)-3. ! new position
        ZXPLANE(5)=3092.7        ! new position
        ZYPLANE(5)=ZXPLANE(5)-2.7 ! new position
        SHIFTX(1)=1001.         ! old MWPC #1 removed
        SHIFTY(1)=1001.         ! old MWPC #1 removed
        SHIFTX(5)=0.343         ! ref. run #7979
        SHIFTY(5)=-1.105        ! ref. run #7979
      else
        print *,' '
        print *,' *** To work with MWPC data this period should be ',
     +    'initialized! irunpd=', irunpd
        print *,' ***      Look subroutine beam_ini !!!'
        print *,'STOPPING!!!! '
        stop
      endif
      return
      end