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FRITIOF (FTF) Model Implementation in GEANT-4 Package

FRITIOF (FTF) Model Implementation in GEANT-4 Package. V. Uzhinsky, LIT JINR, Dubna. Content. Main ingredients of FTF model A problem formulation String mass sampling String fragmentation Conclusion Plans. FRITIOF model for PP, π P, KP, hA and AA-interactions

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FRITIOF (FTF) Model Implementation in GEANT-4 Package

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  1. FRITIOF (FTF) Model Implementation in GEANT-4 Package V. Uzhinsky, LIT JINR, Dubna Content • Main ingredients of FTF model • A problem formulation • String mass sampling • String fragmentation • Conclusion • Plans FRITIOF model for PP, πP, KP, hA and AA-interactions was proposed by B. Andersson et al. in Nucl. Phys. 281B (1987) 289. Program implementation was given by B. Nilsson-Almquist andE. Stenlund in Comp. Phys. Comm. 43 (1987) 387.Now it is used in UrQMD, HIJING, ART MC generators. It is a good competitor to QGSM. 1

  2. Main ingredients of FRITIOF Model M1 1. Physics assumption M2 2. Sampling of string masses 3. LUND string fragmentation model (JETSET 6.2) 2

  3. GEANT-4 Implementation of FRITIOF Model In release 4.8.3 we return to the original FRITIOF model. Sampling parameters String fragmentation was not essential changed. 3

  4. Problem formulation: PP interactions. Topological cross sections FTF describes the data better than QGSM 4

  5. Problem formulation: PP interactions. Particle multiplicity FTF describes the data better than QGSM 5

  6. Problem formulation: PP interactions. Inclusive cross sections All O.K. for PP-interactions 6

  7. Problem formulation: πP interactions. Topological cross sections FTF describes the data better than QGSM 7

  8. Problem formulation: πP interactions. Inclusive cross sections It must be improved 8

  9. Problem formulation: πP interactions. • There are 2 possibilities: • Change of string mass sampling algorithm; • Change of string fragmentation. M1 String mass sampling M2 • Questions: • What to do with binary • channels? • 2. M low for sampling? • 3. M low of string masses? • 4. How to treat diffraction? • 5. Mass distribution? • 6. For MN interactions • most points are at the • left lower corner!!! • 7. Etc. 9

  10. String mass sampling. 10

  11. String mass sampling. 3 parameters were tuned – string mass sampling limit, diffractive mass cut-off, and “a”. New FTF gives good results for central region 11

  12. String mass sampling. New FTF gives good results for central region 12

  13. String mass sampling. The same was done for KP-interactions, and parameter a=0.5 has been found. A good description of meson-nuc- leon interactions has been reached. Models Topological cross sections are well! 13

  14. String mass sampling. Problem! Results for π-A interactions The results for nuclear target are not quite well. 14

  15. String fragmentation algorithm in QGSM (G4VLongitudinalStringDecay.cc) Main routine: FragmentString LightFragmentationTest (for selection of on-shell hadrons * *** StopFragmenting ? FragmentationMass FragmentationMass SplitUp QuarkSplitup CreatePartonPair DiQuarkSplitup SplitEandP (soft kinematics check) * IsFragmentable ? (new string) In many cases binary isotropic decay of a string takes place! Fragmentation functions do not work! QuarkSplitup SplitLast DiQuarkSplitup Isotropic decay Two different conditions for an End of fragmentation! There is no isotropic decay in LUND fragmentation! 15

  16. Conclusion We have some improvement of FTF Implemented 1 2 Some parameters are tuned, and we have a good description of πp and Kp interactions 3 Results for πA interactions are not satisfactory ones It is needed to change string fragmentation 16

  17. Plans 1.Improve string fragmentation algorithm and reach a good description of πA and KA interactions (august, september). 2. Implement of simulation of nucleus-nuc- leus interactions (to the end of the year). 3. Reach a good description of AA interac-tions (to the end of the year or maybe more). 4. Implement the collective flow in FTF. 5. Implement the HIJING model in G4. 17

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