The polarization observables are sensitive to the two nucleon (2NF) and three-nucleon structures (3NF) of the nuclei. The aim of the deuteron spin structure (DSS) experiment is to obtain polarization observables in dp elastic scattering at large CMS angles (> 60 °) and in dp breakup. Of great importance is the study of polarizations observables in these reactions at intermediate energies because the experimental and theoretical data are very scarce. In this review, results of vector and tensor analyzing powers obtained at JINR Nuclotron at 800 MeV will be presente

Averyanov, A. V.

Chernykh, E. V.

Enache, D.

Mezhenska, O.

Skhomenko, Y. T.

DSpace at Belgorod State University

Journal of Physics: Conference SeriesPAPER • OPEN ACCESSStudy of the polarization observables in dp → dp reaction at the deuteronenergy of 800 MeVTo cite this article: O. Mezhenska et al 2020 J. Phys.: Conf. Ser. 1435 012042 View the article online for updates and enhancements.This content was downloaded from IP address 188.170.217.49 on 20/05/2021 at 14:13Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distributionof this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.Published under licence by IOP Publishing LtdXVIII Workshop on High Energy Spin Physics "DSPIN-2019"Journal of Physics: Conference Series 1435 (2020) 012042IOP Publishingdoi:10.1088/1742-6596/1435/1/0120421Study of the polarization observables in dp→ dpreaction at the deuteron energy of 800 MeVO. Mezhenska1, A.V.Averyanov2, E.V.Chernykh2, D.Enache3,Yu.V.Gurchin2, A.Yu.Isupov2, M.Janek4, J-T Karachuk2,3,A.N.Khrenov2, D.O.Krivenkov2, P.K.Kurilkin2, V.P.Ladygin2,N.D.Ladygina2, A.N.Livanov2, S.M. Piyadin2, S.G. Reznikov2,Ya.T.Skhomenko2,5, A.A.Terekhin2, A.V.Tishevsky2, T.Uesaka5,J.Urban11Pavol Jozef Safarik University in Kosice, Srobarova 2, 04180 Kosice, Slovak Republi2Joint Institute for Nuclear Research, Joliot-Curie, 6, Dubna, Moscow region 141980, Russia3National Institute for R&D in Electrical Engineering ICPE-CA, 313 Splaiul, District 3,Bucharest -030138, Romania4Physics Department, University of Zilina, Univerzitna 1, SK 01026 Zilina, Slovak Republic5Belgorod State National Research University, 85, Pobedy St., Belgorod, 308015, RussianFederation6Nishina Center for Accelerator-Based Science, RIKEN, 2-1 Hirosawa, Wako, Saitama351-0198, JapanE-mail: olena.mehenska@student.upjs.skAbstract. The polarization observables are sensitive to the two nucleon (2NF) and three-nucleon structures (3NF) of the nuclei. The aim of the deuteron spin structure (DSS) experimentis to obtain polarization observables in dp elastic scattering at large CMS angles (> 60◦) andin dp breakup. Of great importance is the study of polarizations observables in these reactionsat intermediate energies because the experimental and theoretical data are very scarce. In thisreview, results of vector and tensor analyzing powers obtained at JINR Nuclotron at 800 MeVwill be presented.1. IntroductionUnderstanding the nature of the nuclear force is one of the most important questions in nuclearphysics. A detailed knowledge of the nuclear force provides description of the nuclear propertiesand their reactions. Nowadays, from experimental side, high precision data on nucleon - deuteron(Nd) scattering process exsist in a large energy range [1, 4]. From theoretical side, differenttheoretical models, such as meson-exchange potentials, chiral perturbation theory, etc. providegood descriptions of the few nucleon forces phenomena. At present,the two nucleon force (2NF)models provide a good description of the experimental data of proton-proton and neutron-protonscattering and of the properties of the deuteron, such as the binding energy and D wave content.For the three nucleon (3N) system, the use of only 2NF is not enough. The presence of a thirdnucleon in a 3N system can influence the characteristic of all three nucleons. This effect whichexists in the 2N interaction is called three nucleon force (3NF). Measurements of diffential crosssections in NN elastic scattering process is a tool to study the 3NF. For istance, the spin-depentXVIII Workshop on High Energy Spin Physics "DSPIN-2019"Journal of Physics: Conference Series 1435 (2020) 012042IOP Publishingdoi:10.1088/1742-6596/1435/1/0120422part of the 3NF can be studied by measuring the vector and tensor analyzing powers usingpolarized deuteron or proton beams.During the last several years, polarization observables in Nd elastic scattering have beenstudied in a number of experiments at RNCP [1], KVI [2], RIKEN [3], IUCF [4] etc. Theseexperiments were stimulated by the observed discrepancy beetween differential cross sectiondata at the energies of 65-135 Mev/nucleon [5, 6] and theoretical calculations. Many of thedescrepancies for the differential cross section and vector analyzing powers at these energiesare remedied by the inclusion of the 3NFs such as TM-3NF [7], Urbana IX-3NF [8] or TM99[9]. However, theoretical models with 3NFs still have difficulties in reproducing polarizationobservables, e.g. tensor analyzing powers. At energies 200-600 MeV/nucleon, large discrepanciesbetween the experimental data and theoretical predictions in the minimum of the differentialcross section are persistent after inclusion of 3NFs [10, 11]. It has been found that whenonly NN forces are included into the calculations, the relativistic effects are significant onlyat backward scattering angles. They are relatively small in the minimum of the differentialcross section [12]. Howewer, inclusion 3NF into theoretical models does not allow to get anagreement with the polarization observables experimental data obtained at 400-1800 MeV [14].The reason of the deviation can be associated with the neglected 3N short range correlation [15].Despite of significant progress in the development of theoretical calculations which include 3NFand relativistic effects into the investigation of few nucleon systems at intermediate energies stillmany open questions persist. The main goal of the Deuteron Spin Structure (DSS) experimentalprogram at the Nuclotron internal target station (ITS) [19] is to obtain information about on thespin-dependent parts of 2NF and 3NF in two processes: dp-elastic scattering in a wide energyrange and dp-breakup at energies 300 – 500 MeV [16–18] .In the present work new results on the analyzing powers Ay, Ayy and Axx from dp elasticscattering measured at the incident deuteron energy of 800 MeV and in angular range from60◦ to 135◦ obtained by DSS are reported. They are compared with the results of theoreticalprediction.2. Experimental setupThe experiment was performed in Laboratory of High Energy Physics of Joint Institute forNuclear Research on DSS ITS at the Nuclotron. The setup is well suited for the study ofthe dp reactions at large scattering angles in the center-of-mass system (CMS). In the currentexperiment polyethylene target of 10µm was used for the measurements. The yield from Carboncontent of the CH2 is estimated in separate measurements using several twisted 8µm carbonwire.Polarized deuterons were provided by polarized ion source SPI [20] at the energy of 270MeV [22]. In the current experiment the spin modes with the maximal ideal values of(pz, pzz) = (0, 0), (−1/3,+1), (−1/3,−1) were used. The typical values of beam polarizationdiffer from ideal values about 65-75% [21]. The detection of the dp elastic scattering eventshas been done by deuteron and proton registration in coincidence. Selection of the dp elasticscattering events has been done by the kinematical coincidence of the scattered deuterons andrecoil protons. The same method was used to obtain the polarisation observables data in elasticscattering reaction at 880 MeV [23], 2000 MeV [24] and in energy range 400-1000 MeV [14].3. Measurements of analyzing powersThe selection of the dp-elastic scattering events is done by the correlation of the energy lossesin plastic scintilation counters and their time-of-flight difference [25]. The normalized numberof useful events is used for analyzing power calculations. The CH2 − C subtraction procedureis performed to obtain the reaction on Hydrogen.XVIII Workshop on High Energy Spin Physics "DSPIN-2019"Journal of Physics: Conference Series 1435 (2020) 012042IOP Publishingdoi:10.1088/1742-6596/1435/1/0120423*Θ0 20 40 60 80 100 120 140 160 180yA0.8−0.6−0.4−0.2−00.20.40.60.8=800 MeVdT∆ONE+SS+DS+ONE+SS+DSONE+SSH2CH2PRELIMINARYa)*Θ0 20 40 60 80 100 120 140 160 180yyA1−0.5−00.511.5=800 MeVdT∆ONE+SS+DS+ONE+SS+DSONE+SSH2CH2PRELIMINARYb)*Θ0 20 40 60 80 100 120 140 160 180xxA1.5−1−0.5−00.511.5=800 MeVdT∆ONE+SS+DS+ONE+SS+DSONE+SSH2CH2PRELIMINARYc)Figure 1. Angular dependencies of the vector Ay and tensor Ayy, Axx analyzing powers for thedp-elastic scattering at 800 MeV. The curves are described in the text.The angular dependencies of the vector Ay and tensor Ayy, Axx analyzing powers in deuteron-hydrogen reaction at the energy of 800 MeV are presented in Fig.1. The results obtained atpolyethylene are denoted by open black symbols, hydrogen analyzing powers presented by fullred symbols. It shoud be noted, that the discrepances between CH2 and H2 data are about 10%.The dashed-dotted, dashed and solid curves are the calculations performed within the relativisticmultiple scattering expansion formalism [26] considering one nucleon exchange (ONE) and singlescattering (SS) terms, with the double scattering (DS) contribution and ∆-isobar exitation,respectively. It is shown that the model which includes only one-nucleon exchange and singlescattering is suitable for describing the behavior of tensor analyzing power Axx in all angularrange but does not reproduce the behavior of Ay and Ayy. Inclusion of the double scattering and∆-isobars improves the description of Ayy experimental data obtained at the central scatteringangles.XVIII Workshop on High Energy Spin Physics "DSPIN-2019"Journal of Physics: Conference Series 1435 (2020) 012042IOP Publishingdoi:10.1088/1742-6596/1435/1/01204244. ConclusionsThe vector Ay and tensor Ayy, Axx analyzing powers for the dp-elastic scattering have beenmeasured for the first time on Internal Target Station at 800 MeV over the c.m. angular rangefrom 60◦ to 135◦. New results on the vector analyzing power Ay and tensor analyzing powerAyy, in contrast to tensor analyzing power Axx, indicate strong deviations from the predictionsof the relativistic approaches based on the nucleon-nucleon forces only.Some differencies in the description of the analyzing powers require consideration of additionalmechanisms, e.g. 3NFs. Since the present 3NFs models cannot improve the agreement with thedata obtained at this energies, new models of 3NFs should be considered.5. AcknowledgmentsThe authors thank the Nuclotron staff for providing good conditions of the experiment. Theythank A.S. Belov, V.B. Shutov and V.V Fimushkin for the tune of the SPI [19]. They express thegratitude to S.N. Bazylev, V.I. Maximenkova, I.V. Slepnev, V.M. Slepnev and A.V. Shutov forthe help during the preparation of the detector and DAQ system. The work has been supportedin part by the RFBR under grant No19-02-00079a, by the Ministry of Education, Science,Research, and Sport of the Slovak Republic (VEGA Grant No. 1/0113/18), by JINR-SlovakRepublic and JINR-Romania scientic cooperation programs in 2016-2018.References[1] Yagita T et al. 2003 Mod. Phys. Lett. A 18 322[2] Stephan E et al. 2010 Phys. Rev. C 82 014003[3] Sekiguchi K et al. 2009 Phys. Rev. C 63 054008[4] Egiyan K S et al. 2006 [CLAS Collaboration] Phys. Rev. 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Study of the polarization observables in dp → dp reaction at the deuteron energy of 800 MeV

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Study of the polarization observables in dp → dp reaction at the deuteron energy of 800 MeV

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