1 / 10

Rotating strings in anti-proton proton annihilations V. Uzhinsky, 1 5 Nov. 2017

Simulating anti-deuterons incident on silicon reveals anisotropic distribution of secondary pions in antiproton annihilation at rest. Rotating strings are implemented to improve angular distributions in Monte Carlo simulations.

withrowj
Download Presentation

Rotating strings in anti-proton proton annihilations V. Uzhinsky, 1 5 Nov. 2017

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Rotating strings in anti-proton proton annihilations V. Uzhinsky, 15 Nov. 2017 Questions dwright@slac.stanford.edu Wed, 4 Oct 2017 21:35:02 Subject: anti-deuterons in FTF Hi Vladimir, We have a user here at SLAC who is simulating anti-deuterons incident on silicon. He sends in a 1 keV anti-deuteron, which I assume is handled by FTF. What he sees is that the deuteron splits into anti-proton and anti-neutron, and 50% of t he time the anti-neutron is left at rest, while the anti-proton always has some kinetic energy. Do you know why this is the case? Should n't the anti-neutron always some energy, even if it is not much? This leads to another problem: because FTF derives from a discrete process, and because the anti-neutron is neutral, there is no physics process assigned to the at rest anti-neutron. It does not interact at all. This we can fix, but it would be good to now why there are zero energy anti-neutrons being produced in the first place. Dennis Problem 1910 -  anisotropic distribution of secondary pions from antiproton annihilation at rest Reported: 2016-11-14 10:09 CET by Jongwon Hwang I wrote the code for antiproton annihilation at rest by using FTFP_BERT_TRV physics, which uses Fritiof model for the annihilation. Checking the angular distribution of secondary pions from the antiproton annihilation at rest (in any material), it is not isotropic. 1) cosine(theta): not uniform 2) phi: uniform where (r, theta, phi) is the momentum direction using the general spherical coordinate with respect to the z-axis.

  2. Denni’s question Unsuccessful attempt to implement secondary particle cascading after annihilation // Uzhi March 2016 // theParameters->SetProbabilityOfAnnihilation( 0.0 ); // Uzhi March 2016 // Uzhi 17 Oct. 2017 2

  3. Angular distribution of annihilation products Exp. data: Where is isotropy? 3

  4. Main idea Annihilation at rest Idea: Randomly izotrophically rotate string! 4

  5. Improvement of G4FTFAnnihilation.cc G4bool RotateStrings = false; // Uzhi 17 Oct. 2017 G4LorentzRotation RandomRotation; if(G4UniformRand() <= G4Pow::GetInstance()->powA(1880.0/SqrtS, 4.0)) { RotateStrings = true; RandomRotation.rotateZ(2.*pi*G4UniformRand()); RandomRotation.rotateY(std::acos(2.*G4UniformRand()-1.)); } // Uzhi 17 Oct. 2017 if(RotateStrings) // Uzhi 17 Oct. 2017 { G4LorentzVector Pquark = G4LorentzVector(0.,0., SqrtS/2., SqrtS/2.); Pquark *=RandomRotation; G4LorentzVector Paquark = G4LorentzVector(0.,0.,-SqrtS/2., SqrtS/2.); Paquark *=RandomRotation; Pquark.transform(toLab); projectile->GetNextParton()->Set4Momentum(Pquark); Paquark.transform(toLab); projectile->GetNextAntiParton()->Set4Momentum(Paquark); } // Uzhi 17 Oct. 2017 5

  6. Results 6

  7. Results Average PT must depend on energy! 7

  8. Results All OK! 8

  9. Results More elaborated approach is needed! 9

  10. Summary Bug is fixed for anti-nucleus nucleus interactions! Rotating strings are implemented in annihilations. Parameters of the rotation are tuned. Visualization tools are created. For the first time angular distributions of annihilation products are reproduced in the Monte Carlo approach! A more elaborated approach is needed for a description of Pi+ Pi- data.

More Related