HIJING interface
----------------
Khaled Abdel-Waged
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version 0.0, 1-11-2012
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>Installation requirements
--------------------------
The Geant4 interface to HIJING uses the following software tools and packages:
1. HIJING (available at fttp://nta0.lbl.gov/pub/xnwang/hijing)
2. The following Geant4 versions:
− ver.9.5 or above
The interface and original HIJING code have been compiled and tested using:
• gcc 4.1.2 with gfortran (FORTRAN95) and GNUmake)
Operating systems used for this test is:
Red Hat Linux 4.1.2-64
>Changes in the Fortran code
----------------------------
1) The main subroutines
SUBROUTINE HIJSET(EFRM, FRAME, PROJ, TARG, IAP, IZP, IAT, IZT)
is replaced with
SUBROUTINE HIJSET(EFRM)
SUBROUTINE HIJING (FRAME, BMIN, BMAX)
is replaced with
SUBROUTINE HIJING (BMIN, BMAX)
The input variables are directly inserted into the following common block:
COMMON/HIPARNT/HIPR1(100),IHPR2(50),HINT1(100),IHNT2(50)
Projectile:
IHNT2(1)=IAP // Nucleus mass number
or IHNT2(1)=1 //Hadron
IHNT2(2)=IZP //charge
IHNT2(5)=0 //id code
Target:
IHNT2(3)=IAT
IHNT2(4)=IZT
IHNT2(6)=0 //id Target (Fixed)
Rest Mass:
HINT1(8)= //projectile
HINT1(9)= //Target
2) In subroutines HIJSET and HIJING,
Since Geant4 hadronic cascade models always works in the LABoratory frame
the statement Frame=”LAB” is inserted.
3)Random number generator
The two random generator functions become one!
This is done by replacing
RAN(NSEED) with RLU(0) in hijing1.383.f
>Consequences of conversion from f77 (g77) to gfortran
------------------------------------------------------
When running HIJING code in gfortran directly, the execution is blocked.
This problem is solved by the following changes
1) You have to add in the GNUmake file, the line
FFLAGS=-fno-automatic
This treats each program unit as if the SAVE statement were specified
for every local variable and array referenced in it.
2) Problem related to the function ROMG(x) in hijing1.383.f:
FUNCTION ROMG(X)
C This gives the eikonal function from a table
C calculated in the first call
DIMENSION FR(0:1000)
DATA I0/0/
COMMON/EIKONAL/FR !New->Khaled
IF(I0.NE.0) GO TO 100
DO 50 I=1,1001
XR=(I-1)*0.01
FR(I-1)=OMG0(XR)
50 CONTINUE
100 I0=1
IF(X.GE.10.0) THEN
ROMG=0.0
RETURN
ENDIF
IX=INT(X*100)
ROMG=(FR(IX)*((IX+1)*0.01-X)+FR(IX+1)*(X-IX*0.01))/0.01
RETURN
END
Our analysis shows that the array FR() is not saved in the subsequent calls of the function ROMG().
Therefore, the statement “COMMON/EIKONAL/FR” is inserted, as shown above.
>Interface design
-----------------
The use of HIJING physics in Geant4 has resulted in the introduction of a new event model (G4HIJING_Model).
The G4HIJING_Model class is derived from G4HadronicInteraction, and is defined within the Geant4 user physics
list if access to HIJING physics is required. It controls initialisation of HIJING through common block variables.
Gabriele Cosmo