1. V. V. Glagolev, G. Martinská, J. Mušinský, N. M. Piskunov, J. Urbán Joint Institute for Nuclear research, 141980 Dubna, RUSSIA P.J. Šafárik University, Jesenná 5, Košice, Slovak Republic 6/10/2009J. Urbán1

2. The dp→(pp)n Charge Exchange Channel ABSTRACT An estimate of the spin dependent part of the np→ pn exchange amplitude was made on the basis of the dp→(pp)n data, taken at 1.67 AGeV/c in a full solid angle geometry. The np →pn amplitude turned out to be predominantly spin dependent. To extend these studies to higher energies the designed experiment STRELA is well on the way to data taking and processing. 6/10/2009J. Urbán2

3. The dp→(pp)n Charge Exchange Channel Outline Introduction Formalism Experimental results STRELA Conclusion 6/10/2009J. Urbán3

4. The dp→(pp)n Charge Exchange Channel np → pn charge exchange dp →ppn reaction channel: - d is a fast system - the break-up predominantly processes as a quasi NN - charge exchange either np → pn or via inelastic intermediate state 6/10/2009J. Urbán4 Introduction

5. The dp→(pp)n Charge Exchange Channel dp →(pp)n charge exchange: - 2 protons in the same spin state - Pauli principle - What will come out of this state ? 6/10/2009J. Urbán5 Introduction comparison : np →pn and dp →(pp)n

6. The dp→(pp)n Charge Exchange Channel Connects the dp →(pp)n charge exchange with the elementary np →pn process The formalism is based on Pomeranchuk and Chew ideas, published in 1951 I. Pomeranchuk, Sov. JETF 21, 1113 (1951) G.F. Chew, Phys. Rev. 84, 710 (1951) 6/10/2009J. Urbán6 Formalism

7. The dp→(pp)n Charge Exchange Channel The mathematical formalism elaborated by Dean is based on two assumptions, on the validity of: - impulse approximation and - closure approximation. N.W. Dean, Phys. Rev. D5, 1661(1972) and D5, 2832(1972) R. Lednický and Lyuboshitz showed that at relativistic energies these two assumptions are justified 6/10/2009J. Urbán7 Formalism

8. The dp→(pp)n Charge Exchange Channel 6/10/2009J. Urbán8 Formalism  The differential cross section of the elementary pn  np CE can be represented as sum of the spin-independent (SI) & spin-dependent (SD) parts: (d  /dt) np  pn =(d  /dt) SI np → pn +(d  /dt) SD np → pn

9. The dp→(pp)n Charge Exchange Channel 6/10/2009J. Urbán9 Formalism  The differential cross section for dp →(pp)n CE break up in the framework of the impulse approximation and small t is (Dean, Wilkin): (d  /dt) dp  (pp)n = [1-S(t)] (d  /dt) SI np→pn + [1-1/3S(t)] (d  /dt) SD np→pn where S(t) is the deuteron form factor, t is the 4-momentum transfer squared from initial proton to neutron

10. The dp→(pp)n Charge Exchange Channel 6/10/2009J. Urbán10 Formalism  At 0 scattering angle t=0, S(0)=1 and the formula reduces to (d  /dt) dp  (pp)n = 2/3(d  /dt) SD np→pn The CE break-up reaction of the unpolarized deuteron on the unpolarized proton-target in the forward direction is determined by the spin-flip part of the np  pn CE process at 0 scattering angles. Deuteron acts as a spin filter. This result also remains valid when the deuteron D-state is taken into account.

11. The dp→(pp)n Charge Exchange Channel  To extract the information we compare our experimental data ( CE differential cross section at t=0) with the np →pn (CE cross section) data at the same energy available in the literature 6/10/2009J. Urbán11 Formalism

12. The dp→(pp)n Charge Exchange Channel Experimental results The 1m HBC LVE JINR irradiated in beams of deuterons p d = 3.35 GeV/c. 17 dp channels identified About half of the statistics dp →ppn pionless break- up In total 237 413 events 6/10/2009J. Urbán12 Reactions Number of events 1. ppn 102 778 2. ppn(    31 295 3. p   nn 65 284 4. dp 16 184 5. dp   3 950 6. dp     1 839 7. d   n 4 963 8. d   n   1 843 9.     nn 315 10. ppp   5 487 11. ppp     167 12. ppp       67 13. pp     n 1 163 14. pp     n   49 15. dp     576 16. dp       39 17. dp         1 414

13. The dp→(pp)n Charge Exchange Channel Experimental results d p →p p n:  Charge retention d p →(p n) p d p →(p n) p ~ 83 %  Charge exchange d p →(p p) n d p →(p p) n ~ 17 % Neutron is the fastest secondary nucleon in deuteron rest frame  17 512 events 5.85 ± 0.05 mb  This cross section include some part of quasi-pp events with intermediate Δ-isobaric state. 6/10/2009J. Urbán13

14. The dp→(pp)n Charge Exchange Channel Experimental results For IA and at higher energies the role of FSI ! Asymmetry A α= acos(p s q) sensitive to FSI p s -spectator momentum d RF q - 3-momentum transfer from incident to scattering nucleons. FSI suppression 6/10/2009J. Urbán14

15. The dp→(pp)n Charge Exchange Channel Experimental results 6/10/2009J. Urbán15 The basic part intermediate isobars is consequence quasi-рр and quasi- np collisions going through Δ 0, Δ + and Δ ++ - isobars

16. The dp→(pp)n Charge Exchange Channel Experimental results 6/10/2009J. Urbán16 In connection with the appreciable contribution of events with intermediate Δ - isobar it is necessary to enter the amendment on quasi-proton collisions Enhancement occurs above momenta of 0.2 GeV/c

17. The dp→(pp)n Charge Exchange Channel Experimental results 6/10/2009J. Urbán17 For approximation of dp→(pp)n dσ/dt(t = 0) θ LAB < 5° is safe. The 2 protons in LAB have practically identical momenta p 1 = p 2 = p d /2

18. The dp→(pp)n Charge Exchange Channel Experimental results Extrapolation of the dp→(pp)n differential cross section to t=0 : dσ/dt| t=0 = 30.2±4.1 mb/(GeV/c) 2 Be compared with that of np→pn. 6/10/2009J. Urbán18

19. The dp→(pp)n Charge Exchange Channel Experimental results 6/10/2009J. Urbán19 CE np→pn dσ/dt| t=0 using G.Bizard et al:Nuclear Physics B85(1975) 14-30 J.Bystricky, F.Lehar:Nucleon-Nucleon Scattering data, editors H. Behrens and G. Ebel, Fachinformationszentrum Karlsruhe,1978 Edition,N 11-1, p.521 (dσ / dt)| t = 0 = 54.7 ± 0.2 mb/(GeV/c) 2

20. The dp→(pp)n Charge Exchange Channel Experimental results 6/10/2009J. Urbán20

21. The dp→(pp)n Charge Exchange Channel Experimental results 6/10/2009J. Urbán21 Livermore, Moscow, Ruthefrord, UCRL, Harvard U., Harwell, JINR DLNP, PSI, INP Dubna, LAMPF, LRL, JINR

22. The dp→(pp)n Charge Exchange Channel STRELA 6/10/2009J. Urbán22 Drift chambers D1-D7 D1 - D5 125x125 mm 2 D6 - D7 250x250 mm 2 D xy, D uv 22.5° B = 1.7 T, 0.85 T r max = 2.1 cm, t max ~ 450 ns

23. The dp→(pp)n Charge Exchange Channel STRELA 6/10/2009J. Urbán23 new VME crates and modules tested the basic characteristics of the drift chambers established from irradiation of a polyethylen target with a deuteron beam of 3.5 GeV/c momentum the drift time t min and t max determined for each wire drift time → radius r(t) transformation carried out: - linear (on-line) - cumulative/integral (off-line)

24. The dp→(pp)n Charge Exchange Channel STRELA Track finding and reconstruction track projection for each block of DC, block defined dymanically, 1block > 3 planes track candidates : pairs fired hits from different planes are selected and combinations of tangentials computed for tangetials the distance d to all fired wires is tested if d > d min candiadate refused; d min >> cham resolution if the number of fired wires obeying previous step N hit ≥ N min = 4 then the tangential → track candidate; if more than 1 candidate then that with min∑d used 6/10/2009J. Urbán24

25. The dp→(pp)n Charge Exchange Channel STRELA Track finding and reconstruction xz-track candidate parametrized z=ax + b distance from all N hit is minimized and a,b determined usually in 2-3 iteration steps 6/10/2009J. Urbán25

26. event 104, small chamber 1X event 104, fully reconstructed 2 tracks reconstructed track(s) ‏ 6/10/2009J. Urbán26

27. The dp→(pp)n Charge Exchange Channel STRELA Autocalibration  crucial role of r(t) for the track reconstruction  iterative correction to r(t) using reconstructed tracks  criterion: ∆r = residuals = distance of the reconstructed track to the wire, should have a Gaussian distribution with 0 mean  ∆r vs t constructed, divided into small t intervals, projected to ∆r and the mean is computed and the transformation t →r is corrected for this value …  usually 4 iteration steps are needed 6/10/2009J. Urbán27

28. residual small chamber 3X (14 wires) ‏ tdc : residual residual 6/10/2009J. Urbán28

29. n u m b e r o f i t e r a t i o n residual small chamber 1Y 6/10/2009J. Urbán29

30. event 122, big chamber X iteration 1 iteration 4 6/10/2009J. Urbán30

31. big chamber X small chamber 1X iteration 1iteration 4 6/10/2009J. Urbán31 σ ~ 89 μm σ ~ 122 μm

32. The dp→(pp)n Charge Exchange Channel Conclusion d p →(p p) n np → pn The obtained ratio of the charge exchange differential cross sections at t=0 for d p →(p p) n and np → pn reactions np → pn R = 0.55 ± 0.08 testifies the prevailing contribution of the spin-dependent part to the np → pn cross section scattering Continuation of researches at higher energies on STRELA set up is important STRELA electronics (VME + modules) tested Track reconstruction for STRELA drift chambers tested Auto-calibration improves the reconstruction quality STRELA is ready for data taking and processing 6/10/2009J. Urbán32

33. The dp→(pp)n Charge Exchange Channel Acknowledgement This work was supported by the Slovak Grant Agency VEGA under number VEGA 1/4010/07 6/10/2009J. Urbán33

34. Thank you for Thank you for  the attention  6/10/2009 34 J. Urbán

35. 6/10/200935J. Urbán