TEvtGen/PHOTOS/phint1.F

   1       FUNCTION PHINT1(IDUM)
   2 C.----------------------------------------------------------------------
   3 C.
   4 C.    PHINT:   PHotos INTerference (Old version kept for tests only.
   5 C.
   6 C.    Purpose:  Calculates interference between emission of photons from
   7 C.              different possible chaged daughters stored in
   8 C.              the  HEP common /PHOEVT/.
   9 C.
  10 C.    Input Parameter:    commons /PHOEVT/ /PHOMOM/ /PHOPHS/
  11 C.
  12 C.
  13 C.    Output Parameters:
  14 C.
  15 C.
  16 C.    Author(s):  Z. Was,                         Created at:  10/08/93
  17 C.                                                Last Update: 15/03/99
  18 C.
  19 C.----------------------------------------------------------------------
  20
  21       IMPLICIT NONE
  22       REAL*8 PHINT,phint1
  23       REAL*8 PHOCHA
  24       INTEGER IDUM
  25       INTEGER NMXPHO
  26       PARAMETER (NMXPHO=10000)
  27       INTEGER IDPHO,ISTPHO,JDAPHO,JMOPHO,NEVPHO,NPHO
  28       REAL*8 PPHO,VPHO
  29       COMMON/PHOEVT/NEVPHO,NPHO,ISTPHO(NMXPHO),IDPHO(NMXPHO),
  30      &JMOPHO(2,NMXPHO),JDAPHO(2,NMXPHO),PPHO(5,NMXPHO),VPHO(4,NMXPHO)
  31       DOUBLE PRECISION MCHSQR,MNESQR
  32       REAL*8 PNEUTR
  33       COMMON/PHOMOM/MCHSQR,MNESQR,PNEUTR(5)
  34       DOUBLE PRECISION COSTHG,SINTHG
  35       REAL*8 XPHMAX,XPHOTO
  36       COMMON/PHOPHS/XPHMAX,XPHOTO,COSTHG,SINTHG
  37       REAL*8 MPASQR,XX,BETA
  38       LOGICAL IFINT
  39       INTEGER K,IDENT
  40 C
  41       DO  K=JDAPHO(2,1),JDAPHO(1,1),-1
  42          IF(IDPHO(K).NE.22) THEN
  43            IDENT=K
  44            GOTO 20
  45          ENDIF
  46       ENDDO
  47  20   CONTINUE
  48 C check if there is a photon
  49       IFINT= NPHO.GT.IDENT
  50 C check if it is two body + gammas reaction
  51       IFINT= IFINT.AND.(IDENT-JDAPHO(1,1)).EQ.1
  52 C check if two body was particle antiparticle
  53       IFINT= IFINT.AND.IDPHO(JDAPHO(1,1)).EQ.-IDPHO(IDENT)
  54 C check if particles were charged
  55       IFINT= IFINT.AND.PHOCHA(IDPHO(IDENT)).NE.0
  56 C calculates interference weight contribution
  57       IF(IFINT) THEN
  58         MPASQR = PPHO(5,1)**2
  59         XX=4.D0*MCHSQR/MPASQR*(1.D0-XPHOTO)/(1.D0-XPHOTO+(MCHSQR-MNESQR)
  60      &     /MPASQR)**2
  61          BETA=SQRT(1.D0-XX)
  62          PHINT  = 2D0/(1D0+COSTHG**2*BETA**2)
  63       ELSE
  64          PHINT  = 1D0
  65       ENDIF
  66        phint1=1
  67       END