An interface between HIJING Geant 4 9 5
An interface between HIJING & Geant 4 -9. 5 Khaled Abdel-Waged Umm Al-Qura University-Saudi Arabia Benha University-Egypt
Contents 1 What is HIJING code? 2 HIJING ingredients 3 Changes in the Fortran code 4 HIJING interface 5 Check of energy-momentum conservation
WHAT IS HIJING CODE? � HIJING (Heavy Ion Jet Interaction Generator) is a code which takes into account the physics of hard or semi hard parton production. Physical Rev. D 44, 3501(1991). � HIJING is used in many experiments (e. g. , ALICE, STAR ) to study: v v multiple jets production. particles produced in high energy pp, p. A and AA collisions. HIJING can also provide initial conditions for parton and hadron cascade models (e. g. , Multiphase Transport model (AMPT code): HIJING+ZPC+Quark coalescence+ ART Physical Rev. C 72, 0641901 (2005)). � q q HIJING uses PYTHIA 5. 3 subroutines to generate kinetic variables for each hard scattering. JETSET 7. 2 for jet fragmentation. 3
HIJING INGREDIENTS � The core component of HIJING is the two-component model for beam parton interactions. � Parton production is divided into rare hard (Pt >P 0) and many (small Pt exchanges ) soft interactions. � The inclusive hard (jet) cross section is determined by perturbative QCD, while the inclusive soft (σsoft) cross section is determined phenomenolgically. � In HIJING (version 1. 383), P 0 =2 Ge. V/c and σsoft =57 mb. In HIJING (version 2), P 0 and σsoft are energy dependent. � 4
PA AND AA-INTERACTIONS � Glauber theory: superposition of binary nucleon-nucleon collisions. � The eikonal formalism is used to determine the probability for a collision to occur. � For a given collision, one determines: elastic, inelastic, soft, hard and the number of jets produced in a hard interaction. � Nuclear Shadowing (modified parton distribution) and Jet Quenching (modified fragmentation) are taking into account. � PYTHIA routines are called to describe kinematics of hard interactions. � Soft interactions are treated according to the LUND model. � Secondary interactions are neglected. 5
STRUCTURE OF HIJING FORTRAN CODE � HIJING code contains 2 files: hijing 1. 383. f and hipyset 1. 35. f. � hijing 1. 383. f contains HIJING subroutines: (27 subroutines and 45 functions). � hipyset 1. 35. f contains PYTHIA and JETSET subroutines (adjusted for HIJING) (68 subroutines and 13 functions) 6
DRIVING HIJING CODE � Initialize HIJING (ONLY ONCE) SUBROUTINE HIJSET(EFRM, FRAME, PROJ, TARG, IAP, IZP, IAT, IZT) EFRM: colliding energy (Ge. V/A) in the frame specified by FRAME: character variables (e. g. , “CMS” or “LAB”). PROJ, TARG: character variables (e. g. “P”, “A”) IAP, IAT: mass number of projectile and target. But 1 for hadrons! IZP, IZT: charge number of projectile and target nucleus. � Generate events (MANY TIMES) SUBROUTINE HIJING (FRAME, BMIN, BMAX) BMIN, BMAX: the minimum and maximum impact parameter. 7
CHANGES IN HIJING CODE The 11 input variables are inserted as follows 1) The HIPARNT common block: COMMON/HIPARNT/HIPR 1(100), IHPR 2(50), HINT 1(100), IHNT 2(50) Projectile: IHNT 2(1)=IAP or IHNT 2(1)=1 IHNT 2(2)=IZP IHNT 2(5)=0 // Nucleus (mass number) //Hadron //charge //id Projectile code Target: IHNT 2(3)=IAT IHNT 2(4)=IZT IHNT 2(6)=0 //id Target (Nucleus assumed) Rest Mass: HINT 1(8)= //projectile HINT 1(9)= //Target 8
2) SUBROUTINE HIJSET(EFRM, FRAME, PROJ, TARG, IAP, IZP, IAT, IZT) is replaced with SUBROUTINE HIJSET(EFRM) !Energy is inserted SUBROUTINE HIJING (FRAME, BMIN, BMAX) is replaced with SUBROUTINE HIJING (BMIN, BMAX) !impact parameter is inserted 3) In HIJSET and HIJING subroutines, the statement Frame=”LAB” !frame is inserted (because Geant 4 hadronic cascade models always works in the LABoratory frame) 9
4) Two random generator functions are called: RAN(NSEED=0) hijing 1. 383. f RLU(0) hipyset 1. 35. f Notice that RAN(0) is not linked to any function!! So, we replace RAN(NSEED) with RLU(0) in hijing 1. 383. f
5) When running HIJING code in gfortran, the execution is blocked!!: FUNCTION ROMG(X) C This gives the eikonal function from a table C calculated in the first call DIMENSION FR(0: 1000) DATA I 0/0/ COMMON/EIKONAL/FR !New->Khaled IF(I 0. NE. 0) GO TO 100 DO 50 I=1, 1001 XR=(I-1)*0. 01 FR(I-1)=OMG 0(XR) 50 CONTINUE 100 I 0=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
GEANT 4 -HIJING INTERFACE � Instantiation of the G 4 HIJING_Model process in Geant 4. � Generation of proton-nucleus and nucleus interaction events.
Instantiate G 4 HIJING_Model Instantisation Initialise C++ variables & G 4 HIJING_Model HIJING common block data HIJING Common blocks accessed through C++ structure declarations Apply. Yourself Determine Initialise HIJING Projectile & Target Common block data for interaction Common blocks Get default Input HIJING parameters and Initialise Projectle/Target by Call to HIJSET Transfer information about secondary products to product vector Simulate interaction by Call to HIJING
HIJINGsrc include G 4 HIJING_Interface. hh G 4 HIJING_Model. hh Src G 4 HIJING_Model. cc hijing 1. 383. f hipyset 1. 35. f make
CLASS DESCRIPTIONS
� G 4 HIJING_Model(cons t. G 4 String & name=HIJING"); public constructor which calls Initialise (). This initialises all of the variables as required by HIJING and held in FORTRAN common blocks based on the DEFAULT values. � ~G 4 HIJING_Model (); Class destructor
� virtual G 4 Had. Final. State *Apply. Yourself (const G 4 Had. Projectile &the. Track, G 4 Nucleus &the. Target); Member function to determine the Final State of the interaction process. The Final state is for the results of (and secondaries from) the projectile, described by the. Track, and the target nucleus, described by the. Target. This member function drives HIJING FORTRAN to enter information about a nuclear-nuclear event, and interprets the results into a product vector as a G 4 Had. Final. State object. � G 4 HIJING_Interface. hh C++ - FORTRAN interface for common blocks and subroutines
CHECK OF ENERGY-MOMENTUM CONSERVATION
CHECK OF ENERGY-MOMENTUM CONSERVATION
Thank you
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