minor coding rule corrections, removed deprecated class

[u/mrichter/AliRoot.git] / TEvtGen / PHOTOS / phocor.F

      FUNCTION PHOCOR(MPASQR,MCHREN,ME)
C.----------------------------------------------------------------------
C.
C.    PHOTOS:   PHOton radiation in decays CORrection weight from
C.              matrix elements
C.
C.    Purpose:  Calculate  photon  angle.  The reshaping functions  will
C.              have  to  depend  on the spin S of the charged particle.
C.              We define:  ME = 2 * S + 1 !
C.
C.    Input Parameters:  MPASQR:  Parent mass squared,
C.                       MCHREN:  Renormalised mass of charged system,
C.                       ME:      2 * spin + 1 determines matrix element
C.
C.    Output Parameter:  Function value.
C.
C.    Author(s):  Z. Was, B. van Eijk             Created at:  26/11/89
C.                                                Last Update: 21/03/93
C.
C.----------------------------------------------------------------------
      IMPLICIT NONE
      DOUBLE PRECISION MPASQR,MCHREN,BETA,XX,YY,DATA
      INTEGER ME
      REAL*8 PHOCOR,PHOFAC,WT1,WT2,WT3
      DOUBLE PRECISION MCHSQR,MNESQR
      REAL*8 PNEUTR
      COMMON/PHOMOM/MCHSQR,MNESQR,PNEUTR(5)
      DOUBLE PRECISION COSTHG,SINTHG
      REAL*8 XPHMAX,XPHOTO
      COMMON/PHOPHS/XPHMAX,XPHOTO,COSTHG,SINTHG
      INTEGER IREP
      REAL*8 PROBH,CORWT,XF
      COMMON/PHOPRO/PROBH,CORWT,XF,IREP
C--
C--   Shaping (modified by ZW)...
      XX=4.D0*MCHSQR/MPASQR*(1.D0-XPHOTO)/(1.D0-XPHOTO+(MCHSQR-MNESQR)/
     &MPASQR)**2
      IF (ME.EQ.1) THEN
        YY=1.D0
        WT3=(1.D0-XPHOTO/XPHMAX)/((1.D0+(1.D0-XPHOTO/XPHMAX)**2)/2.D0)
      ELSEIF (ME.EQ.2) THEN
        YY=0.5D0*(1.D0-XPHOTO/XPHMAX+1.D0/(1.D0-XPHOTO/XPHMAX))
        WT3=1.D0
      ELSEIF ((ME.EQ.3).OR.(ME.EQ.4).OR.(ME.EQ.5)) THEN
        YY=1.D0
        WT3=(1.D0+(1.D0-XPHOTO/XPHMAX)**2-(XPHOTO/XPHMAX)**3)/
     &  (1.D0+(1.D0-XPHOTO/XPHMAX)** 2)
      ELSE
        DATA=(ME-1.D0)/2.D0
        CALL PHOERR(6,'PHOCOR',DATA)
        YY=1.D0
        WT3=1.D0
      ENDIF
      BETA=SQRT(1.D0-XX)
      WT1=(1.D0-COSTHG*SQRT(1.D0-MCHREN))/(1.D0-COSTHG*BETA)
      WT2=(1.D0-XX/YY/(1.D0-BETA**2*COSTHG**2))*(1.D0+COSTHG*BETA)/2.D0
      WT2=WT2*PHOFAC(1)
      PHOCOR=WT1*WT2*WT3
      CORWT=PHOCOR
      IF (PHOCOR.GT.1.D0) THEN
        DATA=PHOCOR
        CALL PHOERR(3,'PHOCOR',DATA)
      ENDIF
      RETURN
      END