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ANALIZING POWER STUDY IN THE REACTIONS INDUCED BY SEVERAL GEV POLARIZED DEUTERONS

ANALIZING POWER STUDY IN THE REACTIONS INDUCED BY SEVERAL GEV POLARIZED DEUTERONS. L.S. Zolin for the SPHERA Collaboration Joint Institute for Nuclear research (Dubna). Outline. Introduction The lesson of spin effect studies at E < 1 GeV

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ANALIZING POWER STUDY IN THE REACTIONS INDUCED BY SEVERAL GEV POLARIZED DEUTERONS

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  1. ANALIZING POWER STUDY IN THE REACTIONS INDUCED BY SEVERAL GEV POLARIZED DEUTERONS L.S. Zolin for the SPHERA Collaboration Joint Institute for Nuclear research (Dubna) Dubna-Spin-05

  2. Outline • Introduction • The lesson of spin effect studies at E < 1 GeV • Deuteron breakup, d(p,p)d-elastic and problems at explanation of NMD(k), T20, ko - data at k > 0.25 GeV/c • GeV polarized deuteron beams as tool to study a spinstructure of short range NN-forces • StudydhAgpXin cumulative regime as means to investigate the deuteron core spin structure • Analyzing powers Ayy(xc,Pt) and Ay(xc,Pt) indhAgpX • SSA indhAgpX and phAgpX , • Azz(x)ofHERMES(b1-data) & Ayy(x) of Dubna • Conclusion Dubna-Spin-05

  3. NN-forces and few nucleon systems • the NN-forces are described by means of phenomenological NN-potentials (NNP) constructed to fit NN-scattering data at lowand intermediate energies. • A range of their applicability is tested by comparison of NNP-based calculations with behavior of observables in NA-reactions. The most powerful NNP-test should content a full set of spin observables. • In E < 1 GeV region a high activity with study of spin observables had place in a number of laboratories ( IUCF, TRIUMF, KVI, RIKEN, RCNP); the main purpose of the latest studies with light nuclei is the search forevidence of a three nucleon forces. Dubna-Spin-05

  4. How much addition of 3NFs can improve an accordance of calculations and exp. data? ’ ’ p + d elast. at 135 MeV/nucleon 2NF calculations-data discrepancies are clearly seen in CS-minimum and at larger c.m. angles. They become larger as an energy is increased 3NFs(2p exchange) improve the description of CS and some spin observables, but not always 3NFs are needed but their spindependent part has some defects K.Sekiguchi et al., PR C70,014001(2004) Dubna-Spin-05

  5. Completeness of data set of spin observables riched in the lastpd-scattering experiments can be illustrated by the IUCF-data(B.v.Przewoski et al. nucl-ex/0411011) • Ay for p & d, Aji and 10 of 12 spin correlation coefficients in p+d –elastic • 2N-force Faddeev calculations with CD-Bonn & AV18 NNP’s within/without 3NFs • IUCF-group conclusion is less optimistic comparing with the pronounced in other experiments: • 3NFs are not successful in explanation of discrepancy between 2N-calculations and data at large angles ’ ’ Dubna-Spin-05

  6. Copious data at intermediate energies show that CS and the spinobservables can not be satisfactory described(the discrepancies ~ 20-30%) even by means of most sophisticated suggested 2NF and 3NF potentials. The discrepancies are most sizeableat scattering angles where the transverse momentum Pt is high and close to threshold (~ 0.4 GeV/c) where quark degrees of freedom (QDF) begin to manifest themselves (rNN<0.6 fm). Several attempts were made to construct SR NNP in the framework of the quark cluster model (QCM). However the test of QCM approaches showed that the nonrelativistic quark models (successful in describing the static properties of single hadrons) fails to reproduce the SR part of the NNinteraction quantitatively [ M.Lacombe et al., PR C65,034004 (2002) , the analysis - up to 350 MeV.]. Dubna-Spin-05

  7. The lesson of spin effect study at intermediate energies (<1 GeV) is to find theoretical approach of correct treatment of relativistic effects and QDF when one probes the NF’s core. A warning point is Pt>= 0.4y0.5 GeV/c. At higher energies (>1GeV) the problem willgain strength. Dubna-Spin-05

  8. E >1GeV - the region of accelerator physics where interests of particle physicists and NN-force physicists are overlapped: The structure of the short-range NN-force cannot be understood without knowledge of nucleonsubstructure. Information on SR NN-forces can be extracted : a) in DIS experiments with light nuclei, available rNN-scale is limited by low cross sections of (e,l)N-reactions ; b) in reactions of nuclei fragmentationwith use h-probes (NA,pA), very low rNN are available (~ 0.2 fm) but interpretation is difficult due to distortion carried in by strong interacting probe. We will discuss here results obtained at fragmentation of polarized deuterons with energies from 1 to 3.65 GeV/nucleon. Dubna-Spin-05

  9. GeV polarized deuteron beams is effective tool to study the deuteron spin structure in the region of deuteron core Single spin asymmetry (SSA) in the reaction with polarized deuterons can be studied without use of expensive polarized target with the large dilution factor. At fragmentation of high momentum deuterons one can test what is internal momentum limit (rNN) for use of the nucleon model of the deuteron at disregard of nucleon substructure. As it was demonstrated by spin experiments at intermediate energies the spin effects are very sensitive to structure of the short range NN-forces. Dubna-Spin-05

  10. GeV deuteron beams permit to extract information of deuteron structure at internal momentum up to k=1 GeV/c In 1982-83 Dubna (dp-breakup) and SLAC (ed-scatt.) data showed that the nucleon mom. distribution in the deuteron deviates from IA-predictions based on standard DWF at k higher 0.25 GeV/c. Some of the models were successful at explanation this discrepancy but they encountered a difficulty atdescription of spin effects in the same region of internal momentumk > 0.25 GeV/c. A.P.Kobushkin, Proc. of the Int.Symp. “Dubna Deuteron-93”,p.71,Dubna,1993 Dubna-Spin-05

  11. Deuteron breakup N(d,p)X and backward elastic scattering p(d,p)d are the reactions where a pole mechanism (ONE) should dominate and IA calculations seems to be well based. However, Saclay and Dubha measurements of the tensor analyzing power T20 and the polarization transferko revealed significant deviations from IA at k > 0.25 GeV/c. Dubna-Spin-05

  12. What is the reason of these discrepancies? Is DWF constructed with realistic NNP not correct at rNN [ 0.4 fm? Comparison of data with different probes at study the same subject could preserve from such a prompt conclusion. In JLAB d(e,de’) experiment t20 was measured up to Q equivalent of k=0.65 GeV/c. Rather good agreement with IA-predictions was observed at use of em-probe. So dN-reactions give a chance to probe the deuteron at very high k (k of 1 Gev/c is reached) but a number of mechanisms affecting on a behavior of observables must betaken into account at data interpretation (FSI,3NF, rescatt. and so on) Q Dubna-Spin-05

  13. Among hadrons probes a meson as mediator of NN-forces might bring a valuable information on SR NN-forces. What sign can identify that the meson is produced at short rNN ? One can use a meson production in dNghXreaction in the cumulative region, with meson momentum above available in NN-interaction. So the cumulative meson can be produced on strongcorrelated NN-pair only (i.e. on the d-core). The invariant variable xcis used for the cumulative reactions. It is defined by 4-mom. conservation: xcPd+PN=Ph+Px, Pd is 4-mom. per nucleon. So xc is min. fragmenting mass (in Mn unit) to produce h. In dNghX xc ranges up to 2. It is a some analog of xF for a case of NA-interaction. Pbeam = 4.5 GeV/c/nucl. Xc gXF at E >> MN Xc/XF - 1< 0.1 at E= 9 CeV Dubna-Spin-05

  14. More motivations for study the reaction dAgpX in the cumulative regime: • Identify the two alternative mechanisms of the cumulative regime • a) based onFermimotion: p is produced by high momentum nucleon • NN->NNp, IAcan be applied to calculate T20 and the prediction • can be compare with data; • b) based on fragmentation 6q-component in the deuteron with hadronization of struck quark into the meson; • no theoretical recipe to predict a behavior spin observables, but one can try to apply Collins or/and Sivers mechanisms to 6q fragmentation for data interpretation; • 2) The large SSA were observed in ppgpX in beam fragmentation region at Pt> 0.5 GeV/c (FNAL data) and atxF > 0.5 (BNL data). One can wait a remarkable spin effectsat d-fragmentation into high momentum pions with high Pt if similar mechanisms dominate at fragmentation of 3q- and 6q-system. Dubna-Spin-05

  15. E704, 200 GeV/c BNL , 22 GeV/c Dubna-Spin-05

  16. VBLHE experimental setup for study an inclusive meson production A(d,p)X Acceptance of the focusing spectrometer -5 sr, DW(Dp/p)=2.4x10 Dp/p=2.2% Momentum range 1.5 to 6 GeV/c TOF 1,2 - correlation 9 Deuteron beam intensity Id = 2x10 d/spill TOF-bases: Ls1-s5 =28m Ls2-s5 = 21m Pzz(+) = 0.640 +- 0.033 +- 0.026 (sys) Pzz(-) = -0.729 +- 0.024 +- 0.029 (sys) TOF-resolution s =0.2 ns Dubna-Spin-05

  17. Tensor analyzing power Ayy in A(d,p)X at Pd=9 GeV/c The sign of Ayy at xc >1 is negative at all Qp (contrary to DPM IA-prediction) Magnitude of Ayy increases with rise of Qp Ayy increases with rise of xc and reaches –0.4 at xc=1.5(close to maximum of D-wave contrib. in DWF) Q and k –dependences in A(d,p)X is contrary toA(d,p)X Dubna-Spin-05

  18. Transverse momentum dependence of Ayy in A(d,p)X Ayy rises in magnitude at increase of Pt from 0.4 to 0.8 Ayy(Pt)-rise is ~linear at Qpof 135 and 180 mrad to find the limit of linear rise a study of higher Pt is desirable Pt-threshold effect near 0.5GeV/c is known for An(ppgpX), it canbe explained byCollins effect (PFF). Ayy(Pt)-effect due to D-state of 6q in the deuteron core. Sivers mechanism (PDF) can be applied to connect Ayy(Pt) with the orbital momentum of 6q (L=2) Dubna-Spin-05

  19. Ayy at fragmentation of 5 GeV/c tensor polarized deuterons At low Pt (Qp~0)Ayy shows weak xc-dependence varying from +0.1 to –0.1 when Pd ranges from 5 to 9 GeV/c The large tensor effects (D-wave) become apparent at xc > 1 with rise of Pt above ~0.4 GeV/c Dubna-Spin-05

  20. Vector analyzing power Ay in A(d,p)X Ay was measured with 9 GeV/c vector polarized d-beam at Qp = 180 mrad Aychanges monotonously from 0.1 to –0.1 at qp increase from 1.5 to 4 GeV/c (0.4 < xc < 1.7, 0.25 < Pt < 0.7) crossing zero near 3 GeV/c where xc = 1 Sign of Ay is similar for both sign of p due to isospin I=0 of the deuteron The significant growth of Ay-magnitude might be at Pt > 0.7 GeV/c as in p(p,p)X at high energies - desirable to measure. ip(+) , o p(-) 180 mrad [ p(-) 135 mrad. Dubna-Spin-05

  21. HERMES hep-ex/0506018, d (e.e’)X - DIS Dubna, A( d, p)X b1 Different x-regions in the deuteron are probed in these two experiments: x < 0.5at HERMES x = 0.5 to 1.6 at Dubna So far, x > 0.9 is not available in ed-DIS Dubna-Spin-05

  22. Conclusion The vector Ay and tensor Ayy analyzing powers were studiedat 5 and 9 GeV/c d-fragmentation into cumulative pions. Those pions permit to probe the deuteron core structureup to rNN ~ 0.2 fm where two correlated nucleon can be studied as 6q-system Ayy shows a linear rise at increase Ptfrom 0.4 to 0.8 GeV/c – the threshold effect similar to AN(Pt) in ppgpX. Ayy(Pt)-effect is connected with the orbital momentum of 6q (D- state in deuteron core) - Sivers mechanism can be applied (PDF). Ay in dpgpX is small due to isospin I=0 (u,d-symmetry of pn-pair). Ay(Pt) can be explane just as AN(Pt) in the framework of Collins effect About a future plan: a) Precision measurements at Pt > 0.7 GeV/c are desirable to find a limit of Ayy(Pt) linear rise and to clarify Pt-dependence of Ay at xc > 1. b)Study polarized deuteron fragmentation into cumulative kaons dpgKX could bring info on strangeness role in spin structure of 6q ( Id > 10 is required) g 10 Dubna-Spin-05

  23. BACK UP 1 Dubna-Spin-05

  24. Ayy at fragmentation of 5 GeV/c tensor polarized deuterons • Ayy at Pd=5 GeV/c was measured to clarify an energy dependence in A(d,p)X (black points) • A(d,p)X against A(d,p)XEd-dependence of Ayy -- is weak in d-breakup A(d,p)X (Ayy is defined by nucleon momentum distribution in the deuteron) -- isremarkable in A(d,p)X (contradicts with NN->NNpproduction mechanism) • Ayy-sign: in A(d,p)X ds( ) > ds( ) Ayy>0 . in A(d,p)X ds( ) < ds( ) Ayy<0 -form of nucleon density distribution in D-state Multiquark fragmentation model: the cumul. meson is produced at hadronization of quark-spectator which has a high mom.(x>1) as result of momentum randomization in 6q. Preferable direction of randomization is along spinaxis: in orbit. mom. plane a constituent movement is regulated by rotation. The result is Ayy(p) < 0 Dubna-Spin-05

  25. NN-forces, which define the structure and features of nuclei, can be studied with use of different probes: lA-, eA-, hA-reactions. • l-probes are point like and weak-disturbing: allow one to operate with an individual nucleon in nucleus volume; their disadvantages are low cross sections • h-probe is the strong force probe, highly effective (large cross section) but rough: its size ~ NF radius; at probing the nucleus structure at SR one needs totake into account an inner structure of h-probe as well. • Nevertheless, the prevailing bulk of nuclear reaction data including spin physics data is obtained with use of h-pobe (p,N) Dubna-Spin-05

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