1 / 17

The pn -system Study at Internal ANKE Experiment

HEPI, Tbilisi State University IKP, Forschungszentrum Jülich. The pn -system Study at Internal ANKE Experiment. David Mchedlishvili. GGSWBS’12. Outline:. Motivation dp →( pp ) s n reaction Experimental setup Single polarised Double polarised Results Cross section

veata
Download Presentation

The pn -system Study at Internal ANKE Experiment

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. HEPI, Tbilisi State University IKP, ForschungszentrumJülich The pn-system Study at Internal ANKE Experiment David Mchedlishvili GGSWBS’12

  2. Outline: • Motivation • dp→(pp)sn reaction • Experimental setup • Single polarised • Double polarised • Results • Cross section • Tensor analysing powers • Spin correlation parameters • First results on ∆ channel • Overview of the future experiment • Summary and outlook

  3. d/d Ayy np Scattering data • Current experimental status of np data • ANKE is able to improve npdatabase by providing a precise data at up to 2.9 GeV/A np charge-exchange np charge-exchange ANKE range ANKE range np forward np forward

  4. → → dp→(pp)1S0n np charge-exchange (large angles) n At small excitation energies in the final pp system 1S0 state → → d ↑n p D ↑p Spin-flip from 3S1,3D1 of the deuteron to 1S0 of the diproton. Data sensitive to spin-flip, isospin-flip transitions. ↑psp ↓p np charge-exchange amplitudes in cm with basis vectors in terms of initial and final cm momentap and p': D.V.Bugg & C.W., Nucl.Phys.A467 (1987) 575

  5. Proof of principle at 1.17 GeV Results: • Method works at Tn = 585 MeV • Application to higher energies Td=1.6, 1.8, 2.27 GeV D.Chiladze et al. PLB 637, 170 (2006) D.Chiladze et al. EPJA,40, 23 (2009) Tn = 585 MeV SAID np amplitudes

  6. Single polarised: Beam: Polarised deuterons at Td=1.2, 1.6, 1.8, 2.27 GeV Target: Unpolarised hydrogen cluster target Objectives: dσ/dq, Axx, Ayy Double polarised: Beam: Polarised deuterons at Td=1.2, 2.27 GeV Target: Polarised ABS cell target Objectives: Ayp, Cx,x, Cy,y Experimental setup Higher Energy 1.2 GeV t

  7. Polarised internal gas target at ANKE • Atomic Beam Source (ABS) provided polarised H gas in the cell • Qy = 0, -1, +1. • Density ≈ 1013 cm-2 • Cell: 20 x 15 x 370 mm3 • Lamb-shift Polarimetry Complications due to cell: • Dedicated beam development involving stacking injections and electron cooling • Background handling

  8. Reaction identification at 1.2 GeV dp→(pp)n andnp→dπ0reactions provide double track events in forward detector: • pp from dp→(pp)n • dpspfrom quasi-freenp→dπ0 ∆tmeas [ns] Fast pp pairs are distinguished from dpsp using time of flight method ∆ttof [ns]

  9. Beam polarimetry Beam polarisation is measured at Td = 1.2 GeV and“polarisation export” technique is applied to higher energies • np→dπ0Pz(SAID Ay for pp→dπ+) • dp→(pp)snPzz(Axx, Ayy from previous ANKE measurements) → → → Normalised count ratio of dp→(pp)snevents for low excited pp pairs (Epp< 3 MeV): → Normalised count ratio of np→dπ0events: Pzup to 70% Pzzup to 80%

  10. Single polarised data: dσ/dq, Axx, Ayy Td = 1.6 GeV Td = 1.8 GeV Td = 2.27 GeV Large discrepancy

  11. → → dp→(pp)1S0n Double polarised data • Epp < 3 MeV

  12. → → dp→(pp)1S0n Double polarised data: Ayp • Epp < 3 MeV • With beam statePz = 0; Pzz = 0. Td = 1.2 GeV Td = 2.27 GeV

  13. → → dp→(pp)1S0n Double polarised data: Cy,yCx,x • Epp < 3 MeV • With beam state Pzz = 0; (Apy, Ady = 0) Td = 1.2 GeV Td = 2.27 GeV

  14. dp→(pp)s∆0reaction Epp<3 MeV Td = 1.6 GeV • Td=1.2GeV • Td=2.27GeV dp→(pp)n dp→(pp)∆0 + ??? Td = 1.8 GeV Main mechanism: One pion exchange Td = 2.27 GeV Valuable information on the modelling of the np→p∆0 amplitudes

  15. Tensor analysing powers dp→(pp)s∆0 High mass region: 1.19 < MX < 1.35 GeV/c2 Td = 1.6 GeV COMPARE! → dp→(pp)snat Td = 1.2 GeV Differences: • Signs are flipped • Axx and Ayy are small at qt=0 Td = 1.8 GeV Valuable constraints on the modeling of the np→p∆0amplitudes Td = 2.27 GeV

  16. Future experiments Measurement of nucleon-nucleon elastic scattering at small angles up to the maximum COSY energy • Byproducts: • pd→(pp)sn: two slow protons detected in the STT • pd→pd: the deuteron is detected in an STT (small angles) or in ANKE (large angles) • pd→(pp)s∆0 : two protons detected in the STT and ∆0 decay products possibly detected in ANKE • pd→pspdX(quasi free pn→dX): fast deuteron detected in ANKE • pd→psp{pp}s π‾: two fast protons detected in ANKE • pd→3Heπ0 : the 3He is detected in ANKE

  17. Summary THANK YOU • dp→(pp)sn observables: • dσ/dq, Axx, AyyatTd = 1.2, 1.6, 1.8, 2.27 GeV • Ayp, Cx,x, Cy,yatTd = 1.2, 2.27 GeV • dp→(pp)s∆0observables: dσ/dm, Axx, AyyatTd = 1.6, 1.8, 2.27 GeV Outlook • Further investigation of the dp→(pp)s∆0reaction by using double polarised data • Extension of the np program at ANKE by using proton beams at COSY

More Related