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Anti-Matter at Accelerators

Simulation of Anti-Nucleus-Nucleus Interactions in Geant4 V. Uzhinsky (CERN and JINR) On behalf of Geant4 collaboration. Anti-Matter at Accelerators. Anti-Proton 1955, Emilio Segre and Owen Chamberlain (Nobel Prize in Physics) -. Anti-Neutron, 1956, Bruce Cork and colleagues (BNL).

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Anti-Matter at Accelerators

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  1. Simulation of Anti-Nucleus-Nucleus Interactions in Geant4 V. Uzhinsky (CERN and JINR) On behalf of Geant4 collaboration Anti-Matter at Accelerators Anti-Proton1955, Emilio Segre and Owen Chamberlain (Nobel Prize in Physics)- Anti-Neutron, 1956, Bruce Cork and colleagues (BNL) Anti-Deuterium, 1965, Antonino Zichichi et al. (CERN), D.E. Dorfan et al. (BNL) Anti-Helium-3, 1974, Y.M. Antipov et al. (IHEP) Anti-Helium-4, March 2011, Star Collab, H. Agakishiev et al. (RHIC) Observation of the antimatter helium-4 nucleus, arXiv:1103.3312, Au+Au, 200 18 Anti-He-4 ALICE Collab. LHC 5 Anti-He-4, QM 2011 1 Discovery of Anti-Nuclei in cosmic rays? - > PAMELA,BESS,AMS,CAPRICE

  2. Geant4 is a toolkit for the simulation of the passage of particles through matter. Its areas of application include high energy, nuclear and accelerator physics, as well as studies in medical and space science. geant4.cern.ch. We use Monte Carlo technique to simulate particle interactions with a matter. • Multiplicity • Types of part. • Momenta • Direction • And so on Pb W ? O l=- alog(RNDM(-1))/Sigma/Rho • Nuclear cross sections; • Antibaryon-baryon interactions; • Processes • Cross sections • Channel cross sections • Inclusive distributions • Validation of the model; • Problems 2

  3. Nuclear cross sections – Glauber approximation 3 For the first time a good description of Pbar D interactions was reached in the paper by V. Franco, R.J. Glauber, Phys. Rev. 142 (1966) 119 High-energy deuteron cross-sections. O.D. Dalkarov, V.A. Karmanov Nucl.Phys.A445:579-604,1985. Scattering Of Low-Energy Anti-Protons From Nuclei. O.D. Dalkarov, V.A. Karmanov, Fiz. Elem. Chast. Atom.Yadra 18 (1987) 1399. Interaction Of Low-Energy Anti-Protons With Nuclei.

  4. Nuclear cross sections – Glauber approximation Generator of inelastic nucleus-nucleus interaction diagrams ComputerPhysics Communications, V 54, 1989, Pages 125-135 S. Yu. Shmakov, V. V. Uzhinskii, A. M. Zadorozhny - DIAGEN 4

  5. Nuclear cross sections – PbarP cross sections New parameterisation of total and elastic cross-sectionsof pbar-p interactions 5

  6. New parameterization of PbarP cross sections 6 σel/σtot=1/(2 Csh)≈1/3, according to the quasi-eikonal approach of the reggeon field theory (K.A. Ter-Martirosyan, A.B. Kaidalov)

  7. 7 New parameterization of PbarP cross sections Chi2/NoF =6652/444≈15 (total), without 132 points – 666/308 ≈2 Chi2/NoF =149/137≈1 (elastic) Total X: 18 points deviate > 10%, 48 points deviate > 5% 61 points deviate > 4% Accuracy of the parameterization = 5 %

  8. Nuclear cross sections – absorption X’s The Glauber approach works well! 8

  9. Antibaryon-Baryon Interactions 9

  10. Antibaryon-Baryon Interactions Diagram “d”, 2-particle decay 10 Prob(2-particle decay)=exp(- B (Mstring – Mth)) LUND Model Jetset 6.2

  11. Antibaryon-Baryon Interactions Diagram “a”, 2-particle decay 11 Main channels of PbarP interactions are reproduced!

  12. Antibaryon-Baryon Interactions Diagram “g”, 2-particle decay 12 All channels of PbarP interactions are reasonable reproduced!

  13. Antibaryon-Baryon Interactions Annihilation at rest 13

  14. Antibaryon-Baryon Interactions 14 The situation is as usual! Some experimental data agree well with our beautiful theory! Some data which do not agree are probably suspect!

  15. Anti-neutrons at Plab=1.4 GeV/c 15 P P Pi+ Pi+ Energy distribution of secondary neutrons, heavy targets Ta U

  16. Simulation of anti-deuteron-nucleus interactions 16 Anti-deuteron momentum 12.2 GeV/c Parameter variations.

  17. Summary 17 1. Anti-nucleus-nucleus cross sections are estimated in the Glauber approach, and implemented in GEANT4. 2. Differential cross sections of Anti-Nucleus-Nucleus scattering are calculated. 3. New implementation of the quark-gluon-string model of baryon annihilation is created. Region: 0 – 1000 GeV/c. 4. First code for simulation of anti-nucleus – nucleus interactions is created. Region: 0 – 1000 GeV/c/nucleon. 5. Quark model works astonishingly well! Geant4 allows now a simulation of anti-matter – matter interaction! 1. Cross sections of annihilation processes? 2. Low mass string fragmentation? 3. Nuclear vertex functions? Questions:

  18. We hope, new experiments will bring exciting results! GEANT4 working group: Vladimir Uzhinsky, Aida Galoyan, Vladimir Ivanchenko, Gunter Folger, John Apostolakis Photographer: V. Rodionov 1. Anti-nucleus-nucleus cross sections are estimated in the Glauber approach, and implemented in GEANT4. 2. Differential cross sections of Anti-Nucleus-Nucleus scattering are calculated. 3. New implementation of the quark-gluon-string model of baryon annihilation is created. Region: 0 – 1000 GeV/c. 4. First code for simulation of anti-nucleus – nucleus interactions is created. Region: 0 – 1000 GeV/c/nucleon. 5. Quark model works astonishingly well!

  19. Astroparticle Physics 6 ( 1997) 379-386

  20. Nuclear cross sections – elastic scattering 20

  21. Nuclear cross sections – elastic scattering The Glauber approach works well! 21

  22. Annihilation Pbar-A at rest. Cu 22 U Simulation of pbar-A at Plab= 608 MeV/c C C U U

  23. Simulation of PbarA interactions 23 Multiplicity distribution of charg. particles at Plab=4 GeV/c Plab= 2 GeV/c, 50 deg.

  24. (PHENIX Collaboration)

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