Biegun, A.

Bodek, Kazimierz

Ciepał, Izabela

Epelbaum, E.

Glöckle, W.

Golak, Jacek

Kalantar-Nayastenaki, N.

Kamada, H.

Kistryn, Stanisław

Kozela, A.

Kłos, B.

Nogga, A.

Skibiński, Roman

Stephan, E.

Sworst, Rafał

Witała, Henryk

Zejma, Jacek

Zipper, W.

Acta Physica Polonica B

English

Jagiellonian Univeristy Repository

Vol. 39 (2008) ACTA PHYSICA POLONICA B No 2INFLUENCE OF THREE-NUCLEON FORCE EFFECTSON POLARIZATION OBSERVABLES OF THE 1H(~d, pp)nBREAKUP REACTION AT 130 MEV∗R. Sworsta, St. Kistryna, E. Stephanb, A. Biegunb, K. BodekaI. Ciepała, E. Epelbaumf,h, W. Gloecklee, J. GolakaN. Kalantar-Nayastenakic , H. Kamadag, B. Kłosb, A. KozeladA. Noggaf , R. Skibińskia, H. Witałaa, J. Zejmaa, W. ZipperbaInstitute of Physics, Jagellonian University, Cracow, PolandbInstitute of Physics, University of Silesia, Katowice, PolandcKernfysisch Versneller Instituut, Groningen, The NetherlandsdInstitute of Nuclear Physics PAN, Cracow, PolandeRuhr-University, Bochum, GermanyfForschungszentrum-Julich, GermanygKyushu Institute of Technology, JapanhBonn University, Germany(Received January 14, 2008)High-precision vector and tensor breakup analyzing powers for the re-action 1H(~d, pp)n at 130 MeV were evaluated for a large phase space region.Results are compared with rigorous theoretical calculations based on real-istic nucleon–nucleon potentials as well as on chiral perturbation theoryapproach. Theoretical predictions generally describe data quite well, onlyin a few cases influence of three-nucleon forces is significant.PACS numbers: 21.30.–x, 24.70.+s, 25.10.+s, 13.75.Cs1. IntroductionThree-nucleon (3N) system is the simplest testing ground for probing thebasic nucleon–nucleon (NN) interaction in a non-trivial environment. Prop-erties of the 3N systems are determined mainly by pairwise NN interaction.However, also additional dynamics related to the presence of the third nu-cleon is expected, a so-called 3N force (3NF). Nowadays precise predictionsfor observables in the 3N system can be obtained via exact solutions of Fad-deev equations with NN potentials and with inclusion of three nucleon force.∗ Presented at the XXX Mazurian Lakes Conference on Physics, Piaski, Poland,September 2–9, 2007.(401)402 R. Sworst et al.The nuclear dynamics is modeled in different ways: in form of a realistic po-tential and a phenomenological 3NF (TM99) [1] or obtained within the chiralperturbation theory [2] (results obtained at N2LO and N3LO are presentedin this paper). In the first stage of data analysis the cross sections have beenevaluated [3, 4]. They showed clearly that the calculations including 3NFbetter reproduce the data than those based on NN potentials only.2. Experimental setupVector and tensor polarized deuteron beam from the AGOR cyclotronof KVI Groningen, with the energy of 130 MeV, was focused on the liq-uid hydrogen target. Charged reaction products were passing a three-planemultiwire proportional chamber (MWPC) and were detected in a scintilla-tor hodoscope (SALAD) consisting of 24 horizontal transmission detectors(∆E) and 24 vertical stopping detectors (E). The detection system coveredlaboratory polar angles between 10◦ and 40◦ and the full range of azimuthalangles. More details can be found in Refs. [3, 4].3. Data analysisThe registered events of interest are coincidences of two charged parti-cles: proton–proton pairs from the 1H(~d, pp)n breakup process or deuteron-proton pairs from the 1H(~d, dp) elastic scattering reaction. For each tele-scope, formed by an overlap of one ∆E strip with one E slab, spectra ofenergy loss versus energy deposited in the stopping detector were built. Verygood separation between protons and deuterons was observed over the wholeenergy and angular ranges. Emission angles of the reaction products were de-termined on the basis of the MWPC information, with the precision of 0.5◦.Kinematical configurations for the breakup channel were defined by polarangles, θ1, θ2, of the two outgoing protons and their relative azimuthal angle,ϕ12. Energies of the protons were determined on the basis of comparisonsof the special calibration runs, in which protons from the elastic scatteringprocess were passing degraders of precise thicknesses, with accurate MonteCarlo simulations. For every chosen configuration events were projected onthe kinematical curve S, given by E2 versus E1 dependence and defined asthe distance along the kinematic curve from the point of minimal E2 value.Intensity of the events for a given polarization P is expressed by:IP (ξ) = I0(ξ)[1 + PZ(−32sinϕAx(ξ) +32cosϕAy(ξ))−PZZ (cosϕ sinϕAxy(ξ)) + PZZ(12sin2 ϕAxx(ξ) +12cos2 ϕAyy(ξ))], (1)where ξ = (θ1, θ2, ϕ12, S), I0(ξ) is the intensity of the events with unpolarizedbeam, PZ , PZZ are vector and tensor polarization respectively, Ax, Ay —Influence of Three-Nucleon Force Effects on Polarization Observables . . . 403vector analyzing powers, Axx, Ayy, Axy — tensor analyzing powers. Elasticscattering events, measured simultaneously with the breakup process, wereused for determining the vector and tensor polarizations of the deuteronbeam. The method of the polarization evaluation is described in Ref. [5].Quality of this procedure has been verified by precise results obtained forthe elastic scattering analyzing powers [6]. In determining the analyzingpowers the breakup events belonging to a given configuration were sortedwith respect to the S value and the azimuthal angle of the first proton.Rates were normalized to the collected charge and a ratio f = IP−I0I0wasconstructed. For a given bin in S the dependence of the ratio f on theazimuthal angle was fitted with the analyzing power values as parameters(see Fig. 1).Fig. 1. An example of the asymmetry for one configuration and one bin in S. Solidline shows a fit of function resulting from Eq. (1) to the ratio f = IP−I0I0withanalyzing powers as parameters.4. ResultsHigh precision vector and tensor analyzing power values were obtainedfor 72 kinematical configurations. In total nearly 1000 data points for eachobservable (Ax, Ay, Axx, Ayy, Axy) were obtained. The data are comparedwith the theoretical predictions based on realistic NN potentials only andincluding TM 3NF. A comparison is done also for the chiral perturbationtheory predictions, at N2LO and N3LO. In this later case only 2N dynamicsis at present available. An example of such comparison is given in Fig. 2.While in general the data are well described by the predictions, there is stillroom for possible improvements in modeling the interaction dynamics. Nolarge effect of 3N forces are visible in many configurations, although in somecases they are manifesting themselves clearly (see Fig. 3 as an example).More detailed global comparisons are currently underway.404 R. Sworst et al.30 60 90 120 150-0.100.10.2Ax30 60 90 120 150-0.06-0.0300.030.06Ay30 60 90 120 150-0.100.10.2Ayy30 60 90 120 15000.10.2Axx30 60 90 120 150S (MeV)-0.100.1AxyN2LON3LO2N2N+TM99ϕ12=80οθ1=25ο, θ2=20οFig. 2. An example of all five breakup analyzing powers measured in the presentedexperiment, for one selected kinematical configuration. Gray bands show the resultsof various theoretical calculations, as specified in the legend.40 80 120-0,200,2Ayy40 80 120 40 80 120 40 80 120 40 80 120 160S (MeV)ϕ12 = 40οϕ12 = 60οθ1, θ2 = 15ο, 15οϕ12 = 80ο ϕ12 = 100ο ϕ12 = 120οFig. 3. The breakup tensor analyzing power Ayy for one pair of proton polar anglesand several relative azimuthal angles (as given in the panels). The meaning of thebands as in Fig. 2.REFERENCES[1] W. Gloeckle et al., Phys. Rep. 274, 107 (1996).[2] E. Epelbaum, Prog. Part. Nucl. Phys. 57, 654 (2006).[3] St. Kistryn et al., Phys. Rev. C68, 054004 (2003).[4] St. Kistryn et al., Phys. Rev. C72, 044006(2005).[5] A. Biegun et al., Acta Phys. Pol. B 37, 213 (2006).[6] E. Stephan et al., Phys. Rev. C76, 057001 (2007).

Influence of three-nucleon force effects on polarization observables of the $^{1}H(\vec{d},pp)n$ breakup reaction at 130 MeV

https://ruj.uj.edu.pl/xmlui/bitstream/handle/item/67842/sworst_kistryn_bodek_ciepal_golak_skibinski_witala_zejma_et-al_influence_of_three-nucleon_force_effects_2008.pdf?sequence=1&isAllowed=y

Influence of three-nucleon force effects on polarization observables of the $^{1}H(\vec{d},pp)n$ breakup reaction at 130 MeV

Abstract

Similar works

Full text

Available Versions

Jagiellonian Univeristy Repository

Influence of three-nucleon force effects on polarization observables of the 1H(d⃗,pp)n^{1}H(\vec{d},pp)n1H(d,pp)n breakup reaction at 130 MeV

Abstract

Similar works

Full text

Available Versions

Jagiellonian Univeristy Repository

Influence of three-nucleon force effects on polarization observables of the $^{1}H(\vec{d},pp)n$ breakup reaction at 130 MeV