4.4.7 SUBROUTINE ZTTISP(P, V, ZEND, FIRST, SIPRP, IPZ, PHI0, PEND, VEND, DST, ZPLA, TRACK, REQX0, X0INT, IGEOM, ERROR) : TRacK InterSection with Plane

This routine tracks a particle with momentum p from v to the last detector element (plane) inside ZEND. It returns the momentum (pend) and position (vend) at this point. It also returns the TKR parameters at the point, the z of the detector plane and the integrated radiation length over the path from v to vend.

ARGUMENTS:

INPUT :

    P : Momentum of track
    V  : Position where P is given
    ZEND : The routine will return the values on the last detector
           plane inside ZPLA.
           If ZEND=0, the perigee parameters will be returned.
    FIRST : TRUE if first call for this track.
    SIPRP : true IP in R-Phi (input if FIRST = FALSE on input)
    IPZ : true IP in Z (input if FIRST = FALSE on input)
    PHI0 : Phi angle to perigee point in R-phi plane
            (input if FIRST = FALSE on input)
    REQX0 : TRUE if the integrated number of radiation length between
            V and VEND is requested.
    IGEOM : Index of the detector description to be used.

OUTPUT :

    FIRST : set to FALSE if any tracking done for this track.
    SIPRP : true IP in R-Phi (output if FIRST = TRUE on input)
    IPZ : true IP in Z (output if FIRST = TRUE on input)
    PHI0 : Phi angle to perigee point in R-phi plane
            (output if FIRST = TRUE on input)
    PEND: Momentum of track (if ERROR <>0 then PEND=P)
    VEND  : Position where PEND is given (if ERROR <>0 then VEND=V)
    DST : Distance travled from V to VEND.
    ZPLA : Z of plane on which the result is.
           If ZPLA=0, the perigee parameters are returned.
    TRACK : TKR parameters for the track.
                 for the track
    X0INT : Integrated number of radiation-lengths along the track
              negative if tracking was done from the outside going in.
    ERROR : error flag :
             0 - no error
             1 - no intersection in barrel.
             2 - track turns back.
             3 - other error.

IMPLICIT INPUTS:

    from /ZTFWD/ : the z and radial extents of the forward detectors
    from /ZTGPT/ : Pointers in /ZTFWD/
    From /PXCONS/ : BMAG, the magnetic field; CONSA, Speed of light.

IMPLICIT OUTPUTS:

    none

CALLED BY :

ZDBREM, generate BREMsstrahlung (see 4.3.9).

CALLED ROUTINE(S):

ZTTPLA (see 4.4.8)

(To get Track intersection with PLAne.)

ZUI2PI (see 4.7.2)

(To bring angle In the range 0 to 2PI.)

VMOD

(CERNLIB routine.)

SIDE EFFECTS:

none

AUTHORS:

M. Berggren, LAL

CREATION DATE:

27-jul-1992