FRITIOF (FTF) Model Implementation in GEANT-4 Package

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Content1. Main ingredients of FTF model2. A problem formulation3. String mass sampling4. String fragmentation5. Conclusion6. Plans

FRITIOF model for PP, πP, KP, hA and AA-interactionswas proposed by B. Andersson et al. in Nucl. Phys. 281B (1987) 289. Program implementation was given by B. Nilsson-Almquist and E. Stenlund in Comp. Phys. Comm. 43 (1987) 387. Now it is used in UrQMD, HIJING, ART MCgenerators. It is a good competitor to QGSM.

V. Uzhinsky, LIT JINR, Dubna

Main ingredients of FRITIOF Model

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1. Physics assumption M1

M2

2. Sampling of string masses

3. LUND string fragmentation model (JETSET 6.2)

GEANT-4 Implementation of FRITIOF Model

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In release 4.8.3 we return to the original FRITIOF model.

Samplingparameters

String fragmentation was not essential changed.

Problem formulation: PP interactions.

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Topological cross sections

FTF describes the data better than QGSM

Problem formulation: PP interactions.

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Particle multiplicity

FTF describes the data better than QGSM

Problem formulation: PP interactions.

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Inclusive cross sections

All O.K. forPP-interactions

Problem formulation: πP interactions.

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Topological cross sections

FTF describes the data better than QGSM

Problem formulation: πP interactions.

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Inclusive cross sections

It must be improved

Problem formulation: πP interactions.

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There are 2 possibilities:1. Change of string mass sampling algorithm;2. Change of string fragmentation.

String mass sampling

Questions:1. 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.

M1

M2

String mass sampling.

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String mass sampling.

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3 parameters were tuned – string mass sampling limit, diffractive mass cut-off, and “a”.

New FTF gives good results for central region

String mass sampling.

12New FTF gives good results for central region

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String mass sampling.

The same was done for KP-interactions, and parametera=0.5 has been found. A good description of meson-nuc-leon interactions has been reached.

Models

Topological cross sections are well!

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String mass sampling. Problem!

Results for π-A interactions

The results for nuclear target are not quite well.

String fragmentation algorithm in QGSM (G4VLongitudinalStringDecay.cc)

Main routine: FragmentString

LightFragmentationTest (for selection of on-shell hadrons

StopFragmenting ? FragmentationMass

SplitUp QuarkSplitup

DiQuarkSplitupCreatePartonPair

IsFragmentable ? (new string)

Two different conditions for an End of fragmentation! There is no isotropic decay in LUND fragmentation!

SplitLast

SplitEandP (soft kinematics check)

FragmentationMass

QuarkSplitup

DiQuarkSplitup

Isotropic decay

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In many cases binary isotropic decay of a string takes place!Fragmentation functions do not

work!

We have some improvement of FTF

Conclusion

Implemented

Some parameters are tuned, andwe have a good description of πp and Kp interactions

Results for πA interactions are not satisfactory ones

It is needed to change string fragmentation

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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.

Plans

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