4.3.7 SUBROUTINE ZDDHIT(PIN, VIN, MSEEN, IGEOM, NLAY, ILMV, POUT, XOUT, DOTKR, TKRP, TKR, RFLOC, Z, MODNR, IHIT, NNEW, NEWTRK, LAYLIS ) : Make DETector hit PoiNTs

NB. UNDER REVISION. DON'T USE !!!!!!!!!!!!!

This routine transforms a track given as by its momentum and and a point on the track (inside the mvx), to instead be given by its TKR parameters extrapolated to the perigee, and to the layers of the mVx. The extrapolation is done without using the information in this detector. Instead the routine also returns the points where the track crosses the layers. It tracks the particle through DELPHI and by doing so smears the trajectory parameters : First, it steps from layer to layer of the mvx, and simulates multiple scattering, and measurement errors. Then, it tracks the particle from the point where it leaves the mvx through the rest of the tracking system and by doing so calculates the weight matrix of the TKR parameters. The parameters are the smeared according to the covariance matrix (with a 5-dim gaussian).

ARGUMENTS:

INPUT :

    PIN   : Momentum of track (format as given by TYPE; true mass is
             PIN(2) (type=SH) or PIN(5) (type=LUND)
    XIN   : Position where P is given ( in mm if TYPE=LUND, cm if TYPE=SH)
    MSEEN : Seen mass of particle.
    IGEOM : Index of the DELPHI description to be used (see TRKN3G.FOR)
    NLAY  : number of layers in mvx for this geometry. If NLAY =0, the
            perigee parameters (VD included) will be returned instead.
    ILMV  : Cylinder-numbers corresponding to the last (i.e. measuring)
            cylinder in each layer of the mvx.
    DOTKR : TRUE if the track extrapolations to each hit layer
            of the VD should be returned. The extrapolations uses
            the information from the rest of the detector, ie. is
            what would be used together with the hit-pattern to
            attempt to associate VD hits with tracks.

OUTPUT :

    POUT   : 3-momentum of particle at outmost hit VD-layer, or
             at perigee if either NLAY=0 or no VD layers hit.
    XOUT   : track position where POUT is given.
    TKR    : TKR parameters with weight matrix at each layer of the Mvx.
             The radius is added as word one.
    TKRP   : TKR parameters with weight matrix at the perigee
             for the track
    RFLOC  : local R-Phi coordinate at each layer of the Mvx
    Z      :            z        "      "   "    "    "  "   "
    MODNR  : Module-number of hit
    IHIT   : hit pattern.
    NNEW   : Number of new tracks generated by interactions (0 if none)
    NEWTRK : Array containing new tracks created, if any.
    LAYLIS : List of detector layers hit by particle :
              LAYLIS(1,i) = number of the i:th hit layer.
                            LAYLIS(2,i) tells if it is a  plane
                            or a cylinder, if it measures or not,
                            and if it is the reference layer.
              LAYLIS(2,i) = 0  : mathematical layer : no material,
                                 no measurement. Ignored in all
                                 calculations
                            1  : seen by a cylinder
                            2  : seen by a plane
                            -1 : particle went through a cylinder, but
                                 was not seen by the detector.
                            -2 : particle went through a plane, but
                                 was not seen by the detector.
                            10 : the layer is a reference cylinder
                            20 : the layer is a reference plane
              LAYLIS(3,i) = No. of radiation lengths in layer.
              LAYLIS(1,i) = -1 -> end of list.

IMPLICIT INPUTS:

    none. (However, the detector geometry must have been previously loaded
       using ZTINI)

IMPLICIT OUTPUTS:

    none.

CALLED BY :

ZDETSI, DETector SImulation (see 4.3.1).

CALLED ROUTINE(S):

ZTCRAD (see 4.4.17)

(To get Cylinder RADius.)

ZTCLEN (see 4.4.18)

(To get Cylinder LENgth.)

ZTCERF (see 4.4.22)

(To get Cylinder Error in R-Fi)

ZTCEZ (see 4.4.23)

(To get Cylinder Error in Z)

ZTTISC (see 4.4.5)

(To get TRacK InterSeCtions with cylinders.)

ZULETD (see 4.7.1)

(To get multiple scattering using Lynch ET Dahl's formulae.)

ZUGAUS (see 4.7.13)

(To get a GAUSsian random number.)

ZUI2PI (see 4.7.2)

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

PXTCPX (see 4.7.4)

(To transform Track parameters on Cylinder to PXpypz)

VZERO,UCOPY,VDOT

(CERNLIB routines)

SIDE EFFECTS:

none

AUTHORS:

M. Berggren, LAL

CREATION DATE:

22-sep-1992