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Study of the 3 He- η System in d-p Collisions

Study of the 3 He- η System in d-p Collisions. J. Smyrski Jag i ellonian University Cracow, Poland. Results of COSY-11 measurements of:. dp  3 He  close to threshold dp  3 He  o production at  threshold dp  3 He X threshold excitation curve.

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Study of the 3 He- η System in d-p Collisions

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  1. Study of the 3He-η Systemin d-p Collisions J. Smyrski Jagiellonian University Cracow, Poland Results of COSY-11 measurements of: dp 3He  close to threshold dp 3He o production at  threshold dp 3He X threshold excitation curve FB-18 Conf., Santos, 2006

  2. Study of the - 3He interaction above 3He- threshold • dp 3He (enhancement of the cross sections due to the 3He FSI) below 3He- threshold • dp 3He 3He o  d po  pp p-  dp  … (resonance-like structures in the excitation functions) bound state FB-18 Conf., Santos, 2006

  3. |fp|2 |f|2 = 1+2aIq+|a|2q2 3He-η scattering length dp 3He questions: • inconsistencies between datasets • contributions from higher partial waves to σtot at Q <10 MeV • |aR|>aI (?) (necessary condition for bounding) data very close to threshold (Q <1 MeV ) needed (A. Sibirtsev et al., Eur. Phys. J. A22(2004)495) Scattering length a=|3.8+0.6|+i(1.6+1.1) fm FB-18 Conf., Santos, 2006

  4. 3He-ηinteraction below threshold γ3He pπ0 X data from MAMI (M. Pfeiffer et al., Phys. Rev. Lett. 92(2004)252001) Binding energy:( -4.4  4.2) MeV Width: 25.6  6.1 MeV FB-18 Conf., Santos, 2006

  5. 3He  ds/dW (pd3H p+) R = ds/dW (pd3He p0) Re(a) < 0 Bound state Re(a) > 0 Virtual state pp+ |Tp+ |2 ? = pp0 |Tp0 + qmTh |2 ~ ~ Structure at the  threshold V. Baru, J. Haidenbauer, C. Hanhart and J. A. Niskanen, Phys. Rev. C68(2003)035203 aR + iaI = (+3.8+i1.6)fm -mixing FB-18 Conf., Santos, 2006

  6. Internal COSY beam:~ 3x1010 deuterons Q(dp 3He) [MeV] Pbeam [GeV/c] Slow ramping Frequency spectrum 9 3.179 3.141 0 3.099 -10 5 min t Δf= 0.2 MHz  Δp = 1.7 MeV/c ΔQ = 0.4 MeV FB-18 Conf., Santos, 2006

  7. COSY-11 detection system T1: dp 3HeX, X= o, T2: dp 3H+, T3: dp  dp T4: dp  dp, pp  pp(QFS) T5: dp  dpo T6: dp  ppp- T7: dp  dp FB-18 Conf., Santos, 2006

  8. Identification of 3He m2 / q2 TOF - p ΔE - p FB-18 Conf., Santos, 2006

  9. CM momentum distribution   FB-18 Conf., Santos, 2006

  10. Missing mass   FB-18 Conf., Santos, 2006

  11. Beam momentum determination Correction: Δplab = -2.013  0.002 (stat.)  0.48 (syst.) MeV/c FB-18 Conf., Santos, 2006

  12. Background subtraction 3.166 GeV/c < pbeam < 3.170 GeV/c Q ~ 6.5 MeV Background: 3.134 GeV/c < pbeam < 3.138 GeV/c FB-18 Conf., Santos, 2006

  13. dp elastic and pp quasi-elastic scattering FB-18 Conf., Santos, 2006

  14. Luminosity determination pp quasi-elastic dp elastic FB-18 Conf., Santos, 2006

  15. TOT(dp 3He) Preliminary Transition amplitudes: L= 0 J=1/2 T0 L= 1 J=1/2 T1- J=3/2 T1+ FB-18 Conf., Santos, 2006

  16. Fig. from C. kerboul et al., PL B181(1986)28 3Hethreshold COSY-11 dp  3He o at -threshold COSY-11 (dp  (3He -) bound3He o) < 0.07 b Further search: dp (3He -) boundppp - FB-18 Conf., Santos, 2006

  17. SATURNE pd3He X threshold excitation curve SATURNE results Spectrometer momentum acceptance C. Wilkin, in “Production and Decay of Light Mesons”, edited by P. Fleury, p.187 FB-18 Conf., Santos, 2006

  18. 3Hethreshold COSY-11 pd3He X threshold excitation curve mmax- 0.5 MeV < mm < mmax mmax- 1 MeV < mm < mmax FB-18 Conf., Santos, 2006

  19. dp  dp ηcross sections Experiment TOT (dp 3He) for Q = 3.6, 6.5, 9.6 MeV Missing mass Preliminary FB-18 Conf., Santos, 2006

  20. Search for the 4He– h bound state in d-d collisions Princilple of measurements Experiment WASA@COSY - d 3He d p • p-- back-to-back emission: θcm~180˚ • 3He is a spectator : pcm~50 MeV/c, θlab~ 50/1500 rad = 1.9˚ FB-18 Conf., Santos, 2006

  21. Summary • High statistics data collected for the dp 3He veryclose to threshold; strong 3He- S-wave interaction confirmed; the cross sections will be published soon • No narrow structures observed inthe excitation curve for dp  3Heonear the production threshold, but 3He- bound state is still not excluded • The cusp structure observed at the SATURNE threshold excitation curve below the  peak was not confirmed • Planned search for the 4He- bound state in the dd 3He p- reaction FB-18 Conf., Santos, 2006

  22. dpelastic scattering at backward cm angles FB-18 Conf., Santos, 2006

  23. Excitation curve for the dp elastic scattering FB-18 Conf., Santos, 2006

  24. COSY-11 detection setup T1: dp  dp T2: dp 3HeX, X=  o, T3: dp  dp, pp  pp(QFS) pbeamQ (dp 3Heη) [GeV/c] [MeV] 3.165 5.7 3.179 9.1 3.191 12.0 3.204 15.1 FB-18 Conf., Santos, 2006

  25. Missing mass distributions dp  dp X FB-18 Conf., Santos, 2006

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