Mitglied der Helmholtz-Gemeinschaft TSU TBILISI STATE UNIVERSITY The pn-system Study at Internal ANKE Experiment HEPI, Tbilisi State University IKP, Forschungszentrum Jülich David Mchedlishvili GGSWBS’12

August 6, 2012 The pn-system Study at Internal ANKE Experiment GGSWBS’12 Outline: o Motivation o dp→(pp) s n reaction o Experimental setup Single polarised Double polarised o Results Cross section Tensor analysing powers Spin correlation parameters First results on ∆ channel o Overview of the future experiment o Summary and outlook

August 6, 2012 The pn-system Study at Internal ANKE Experiment GGSWBS’12 np Scattering data d  /d  A yy  Current experimental status of np data np forward np charge-exchange np forward ANKE range ANKE range  ANKE is able to improve np database by providing a precise data at up to 2.9 GeV/A

August 6, 2012 The pn-system Study at Internal ANKE Experiment GGSWBS’12 np charge-exchange (large angles) ↓p↓p n d → ↑n↑n ↑p↑p ↑p sp p → D dp → (pp) 1 S 0 n → → At small excitation energies in the final pp system 1 S 0 state Spin-flip from 3 S 1, 3 D 1 of the deuteron to 1 S 0 of the diproton. Data sensitive to spin-flip, isospin-flip transitions. np charge-exchange amplitudes in cm with basis vectors in terms of initial and final cm momenta p and p': D.V.Bugg & C.W., Nucl.Phys.A467 (1987) 575

August 6, 2012 The pn-system Study at Internal ANKE Experiment GGSWBS’12 Proof of principle at 1.17 GeV D.Chiladze et al. PLB 637, 170 (2006) D.Chiladze et al. EPJA,40, 23 (2009) Results: Method works at T n = 585 MeV Application to higher energies T d =1.6, 1.8, 2.27 GeV T n = 585 MeV  SAID np amplitudes

August 6, 2012 The pn-system Study at Internal ANKE Experiment GGSWBS’12 Experimental setup Experimental setup Single polarised: Beam: Polarised deuterons at T d =1.2, 1.6, 1.8, 2.27 GeV Target: Unpolarised hydrogen cluster target Objectives: dσ/dq, A xx, A yy Double polarised: Beam: Polarised deuterons at T d =1.2, 2.27 GeV Target: Polarised ABS cell target Objectives: A y p, C x,x, C y,y t Higher Energy 1.2 GeV

August 6, 2012 The pn-system Study at Internal ANKE Experiment GGSWBS’12 Polarised internal gas target at ANKE Atomic Beam Source (ABS) provided polarised H gas in the cell  Q y = 0, -1, +1.  Density ≈ cm -2 Cell: 20 x 15 x 370 mm 3 Lamb-shift Polarimetry Complications due to cell: Dedicated beam development involving stacking injections and electron cooling Background handling

August 6, 2012 The pn-system Study at Internal ANKE Experiment GGSWBS’12 Reaction identification at 1.2 GeV dp→(pp)n and np→dπ 0 reactions provide double track events in forward detector: pp from dp→(pp)n dp sp from quasi-free np→dπ 0 ∆t tof [ns] ∆t meas [ns] Fast pp pairs are distinguished from dp sp using time of flight method

August 6, 2012 The pn-system Study at Internal ANKE Experiment GGSWBS’12 Beam polarimetry Beam polarisation is measured at T d = 1.2 GeV and “polarisation export” technique is applied to higher energies np→d π 0 P z (SAID A y for pp→d π + ) dp→(pp) s n P zz (A xx, A yy from previous ANKE measurements) Normalised count ratio of dp→(pp) s n events for low excited pp pairs (E pp < 3 MeV): → Normalised count ratio of np→d π 0 events: → → → P z up to 70% P zz up to 80%

August 6, 2012 The pn-system Study at Internal ANKE Experiment GGSWBS’12 Single polarised data: dσ/dq, A xx, A yy T d = 1.6 GeV T d = 1.8 GeV T d = 2.27 GeV Large discrepancy

August 6, 2012 The pn-system Study at Internal ANKE Experiment GGSWBS’12 Double polarised data E pp < 3 MeV dp → (pp) 1 S 0 n → →

August 6, 2012 The pn-system Study at Internal ANKE Experiment GGSWBS’12 Double polarised data: A y p E pp < 3 MeV With beam state P z = 0; P zz = 0. dp → (pp) 1 S 0 n → → T d = 1.2 GeV T d = 2.27 GeV

August 6, 2012 The pn-system Study at Internal ANKE Experiment GGSWBS’12 Double polarised data: C y,y C x,x E pp < 3 MeV With beam state P zz = 0; (A p y, A d y = 0) dp → (pp) 1 S 0 n → → T d = 1.2 GeV T d = 2.27 GeV

August 6, 2012 The pn-system Study at Internal ANKE Experiment GGSWBS’12 E pp <3 MeV T d = 1.6 GeV T d = 1.8 GeV T d = 2.27 GeV dp→(pp) s ∆ 0 reaction T d =1.2GeV T d =2.27GeV dp→(pp)n Main mechanism: One pion exchange dp→(pp)∆ 0 + ??? Valuable information on the modelling of the np→p∆ 0 amplitudes

August 6, 2012 The pn-system Study at Internal ANKE Experiment GGSWBS’12 Tensor analysing powers High mass region: 1.19 < M X < 1.35 GeV/c 2 Differences:  Signs are flipped  A xx and A yy are small at q t =0 Valuable constraints on the modeling of the np→p∆ 0 amplitudes dp→(pp) s n at T d = 1.2 GeV → dp→(pp) s ∆ 0 COMPARE! T d = 1.6 GeV T d = 1.8 GeV T d = 2.27 GeV

August 6, 2012 The pn-system Study at Internal ANKE Experiment GGSWBS’12 Future experiments Measurement of nucleon-nucleon elastic scattering at small angles up to the maximum COSY energy Byproducts: pd→(pp) s n: 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→p sp dX (quasi free pn→dX): fast deuteron detected in ANKE pd→p sp {pp} s π ‾ : two fast protons detected in ANKE pd→ 3 He π 0 : the 3 He is detected in ANKE

August 6, 2012 The pn-system Study at Internal ANKE Experiment GGSWBS’12 Outlook  Further investigation of the dp→(pp) s ∆ 0 reaction by using double polarised data  Extension of the np program at ANKE by using proton beams at COSY Summary dp→(pp) s n observables: 1.dσ/dq, A xx, A yy at T d = 1.2, 1.6, 1.8, 2.27 GeV 2.A y p, C x,x, C y,y at T d = 1.2, 2.27 GeV dp→(pp) s ∆ 0 observables: dσ/dm, A xx, A yy at T d = 1.6, 1.8, 2.27 GeV THANK YOU

August 6, 2012 The pn-system Study at Internal ANKE Experiment GGSWBS’12 dp→(pp) 1 S 0 n: Spin observables Define a ratio of form factors by Terms can be separated by measuring with polarized beams/targets: Unpolarised cross section d and p vector analysing powers d tensor analysing powers d-p vector spin correlations d-p tensor spin correlation Unpolarised intensity depends only upon spin-flip amplitudes: D.V.Bugg & C.W., Nucl.Phys.A467 (1987) 575

August 6, 2012 The pn-system Study at Internal ANKE Experiment GGSWBS’12 Introduction: Deuteron charge-exchange pp’ Impulse approximation: = pp relative momentum in cm. = momentum transfer from p to n. E pp = k 2 /m p = excitation energy in final pp state. np charge-exchange amplitudes in cm with basis vectors in terms of initial and final cm momenta p and p': D.V.Bugg & C.W., Nucl.Phys.A467 (1987) 575

August 6, 2012 The pn-system Study at Internal ANKE Experiment GGSWBS’12 Amplitude behavior T d = 1.2 GeV T d = 2.27 GeV | ε| tends to decrease drastically with energy increase

August 6, 2012 The pn-system Study at Internal ANKE Experiment GGSWBS’12 Comparison with SATURNE data SATURNE at T d = 2 GeV ANKE at T d = 2.27 GeV ANKE results are consistent with SATURNE data Polarisation response: SATURNE data at ϑ = 2.1° Mass is taken: 1.1 < M X < 1.3 GeV/c 2