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University of Kashan Iran

Cross-section and analyzing-power measurements in four-nucleon scattering. SPIN2010 Forschungszentrum Jülich (Germany) September 27 - October 2, 2010 A. Ramazani-Moghaddam-Arani University of Kashan, Iran and KVI N. Kalantar-Nayestanaki. University of Kashan Iran. Outline.

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University of Kashan Iran

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  1. Cross-section and analyzing-power measurements in four-nucleonscattering SPIN2010 Forschungszentrum Jülich (Germany) September 27 - October 2, 2010 A. Ramazani-Moghaddam-Arani University of Kashan, Iran and KVI N. Kalantar-Nayestanaki University of Kashan Iran

  2. Outline • Three-nucleon force • Why dd scattering? • Experimental setup • Analysis of the break-up channel • Results • Summary and outlook

  3. Motivation Prediction of 3NF: H. Primakoff et al., Phys. Rev. 55, 1218 (1939) How big is the 3NF? Effective field theory, based on PT (low-energy expansion in QCD): Perturbative calculations of the interactions between nucleons with pions as exchange particles. 3N forces smaller than 2NF 4N forces even smaller than 3NF!! • Sensitive observables • High-presicion measurements

  4. Motivation p + d p +d Large sensitivity to 3NP effects exists in the minimum of the differential cross section H. Witala et al., Phys. Rev. Lett. 81, 1183 (1998) S. Nemoto et al., Phys. Rev. C 58, 2599 (1998)

  5. Influences of 3NF Although the average magnitude of 3NF is much smaller than the one of the 2NF BUT it can be very big for specific parts of the phase space. NN+3NF NN

  6. 3NF in four-body systems More three-body combinations enhancement of the 3NF in expected Deuteron-deuteron scattering

  7. 4N Calculation Status Phys. Rev. C 76, 021001(R) (2007) Deuteron Energy : 3 MeV Below Break-up Threshold

  8. dd Elastic Scattering at 65 MeV/nucleon • Calculation: • Deltuva, Fonseca, et al. • Note: lowest-order terms in Born series expansion of the AGS equations • High energies • Low momentum transfers

  9. Experiment and reaction channels Big Instrument for Nuclear-polarization Analysis Beam: Polarized deuteron Target: Liquid deuterium for dd Target: solid CH2 for dp Beam Energy: 65 MeV/nucleon

  10. Event selection and particle identification for the break-up channel Energy, scattering angles and time-of-flight =(TOFmeas. - TOFrec.) (dp, pd, pp) pd dp pp

  11. Event Selection

  12. Spin Observables Pure tensor polarization

  13. Spin Observables Pure vector polarization

  14. Three-body Break-up Result Cross section = |Invariant matrix|2 * (Phase space factor) 42 configurations 500 data points

  15. Quasi-free dp elastic scattering in the three-body break-up reaction d + d  d + p + n d + p  d + p

  16. Quasi-free dp elastic results

  17. Summary and Outlook • A few final states of the dd scattering at 65 MeV/nucleon have been identified. • Differential cross sections, vector and tensor-analyzing powers for the elastic d+d channel have been measured. • The three-body break-up in dd scattering has been measured in an almost background-free experiment. • The quasi-free part of the three-body break-up data in dd scattering can be directly compared with the results of the dp elastic scattering. • Surprisingly, the T20 results of the quasi-free dp show discrepancy from the dp elastic scattering. • KVI experiments will provide an extensive database in four-nucleon scattering at intermediate energies. • Theoretical calculations for dd scattering at intermediate energies are urgently called for.

  18. Collaborators A.Ramazani-Moghaddam-Arani, H.R. Amir-Ahmadi, A.D. Bacher, C.D. Bailey, A. Biegun, M. Eslami-Kalantari, I. Gašparić, L. Joulaeizadeh, N. Kalantar-Nayestanaki, St. Kistryn, A. Kozela, H. Mardanpour, J. G. Messchendorp, A.M. Micherdzinska, H. Moeini,V. Shende, E. Stephan, E.J. Stephenson, and R. Sworst Thanks for your attention

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