| da0e9ce3 |
1 | FUNCTION PHOFAC(MODE) |
| 2 | C.---------------------------------------------------------------------- |
| 3 | C. |
| 4 | C. PHOTOS: PHOton radiation in decays control FACtor |
| 5 | C. |
| 6 | C. Purpose: This is the control function for the photon spectrum and |
| 7 | C. final weighting. It is called from PHOENE for genera- |
| 8 | C. ting the raw photon energy spectrum (MODE=0) and in PHO- |
| 9 | C. COR to scale the final weight (MODE=1). The factor con- |
| 10 | C. sists of 3 terms. Addition of the factor FF which mul- |
| 11 | C. tiplies PHOFAC for MODE=0 and divides PHOFAC for MODE=1, |
| 12 | C. does not affect the results for the MC generation. An |
| 13 | C. appropriate choice for FF can speed up the calculation. |
| 14 | C. Note that a too small value of FF may cause weight over- |
| 15 | C. flow in PHOCOR and will generate a warning, halting the |
| 16 | C. execution. PRX should be included for repeated calls |
| 17 | C. for the same event, allowing more particles to radiate |
| 18 | C. photons. At the first call IREP=0, for more than 1 |
| 19 | C. charged decay products, IREP >= 1. Thus, PRSOFT (no |
| 20 | C. photon radiation probability in the previous calls) |
| 21 | C. appropriately scales the strength of the bremsstrahlung. |
| 22 | C. |
| 23 | C. Input Parameters: MODE, PROBH, XF |
| 24 | C. |
| 25 | C. Output Parameter: Function value |
| 26 | C. |
| 27 | C. Author(s): S. Jadach, Z. Was Created at: 01/01/89 |
| 28 | C. B. van Eijk Last Update: 13/02/90 |
| 29 | C. |
| 30 | C.---------------------------------------------------------------------- |
| 31 | IMPLICIT NONE |
| 32 | REAL*8 PHOFAC,FF,PRX |
| 33 | INTEGER MODE |
| 34 | INTEGER IREP |
| 35 | REAL*8 PROBH,CORWT,XF |
| 36 | COMMON/PHOPRO/PROBH,CORWT,XF,IREP |
| 37 | SAVE PRX,FF |
| 38 | DATA PRX,FF/ 0.D0, 0.D0/ |
| 39 | IF (MODE.EQ.0) THEN |
| 40 | IF (IREP.EQ.0) PRX=1.D0 |
| 41 | PRX=PRX/(1.D0-PROBH) |
| 42 | FF=1.D0 |
| 43 | C-- |
| 44 | C-- Following options are not considered for the time being... |
| 45 | C-- (1) Good choice, but does not save very much time: |
| 46 | C-- FF=(1.0D0-SQRT(XF)/2.0D0)/(1.0+SQRT(XF)/2.0D0) |
| 47 | C-- (2) Taken from the blue, but works without weight overflows... |
| 48 | C-- FF=(1.D0-XF/(1-(1-SQRT(XF))**2))*(1+(1-SQRT(XF))/SQRT(1-XF))/2 |
| 49 | PHOFAC=FF*PRX |
| 50 | ELSE |
| 51 | PHOFAC=1.D0/FF |
| 52 | ENDIF |
| 53 | END |
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