Vector analyzing powers of deuteron-proton elastic scattering and breakup at 130 MeV

Abstract

Set of vector analyzing power data of the dp elastic scattering and 1 H ( d,pp)n breakup reactions at 130-MeV deuteron beam energy has been measured in the domain of very forward polar angles. The results are compared with theoretical predictions originating from various approaches: realistic nucleon-nucleon (NN) potentials and the NN potentials combined with a three-nucleon force (3NF) model and with predictions based on the ChPT framework. In case of the breakup process, none of the theoretical calculations reveal sensitivity to any of the dynamical effects such as 3NF or Coulomb interaction and they describe the experimental data equally well. For the elastic scattering, the Coulomb correction appears not negligible at very small θ c.m.d . The effect seems to be confirmed by the data. Few-nucleon systems are microscopic laboratories most suited for detailed study of the nucleon-nucleon (NN) interaction dynamics and the nuclear forces. Among them, the system composed of three nucleons (3N) is the simplest nontrivial environment where NN force models can be tested. Properties of 3N systems at medium energies are mainly determined by pairwise NN interaction. There are, however, reasons to assume the existence of additional dynamical effects like three-nucleon force (3NF) related to the presence of the third nucleon, or the Coulomb interaction, very significant in the domain of small polar angles of the emitted protons. Both effects are modeled within different theoretical formalisms.The realistic two-nucleon (2N) forces can be combined with the recent version of the 2π -exchange Tucson-Melbourne (TM) 3NF [1] or in the case of AV18 NN force with the Urbana IX 3NF [2]. Alternatively, 3NF can be generated by an explicit treatment of the isobar excitation within the coupled channel (CC) method [3]. For the 3N system, creation of a -containing state yields an effective 3NF but also two-barion dispersion. These two effects usually compete, and therefore * izabela.ciepal@uj.edu.pl the net effects of including the isobar in the potential are smaller than for approaches with the phenomenological 3NF's. When the chiral perturbation theory (ChPT) is used at the next-to-next-to-leading order (NNLO), the 3N contributions arise naturally, fully consistently with the NN force terms [4].The long-range electromagnetic component of the NN interaction was successfully implemented in CC formalism [5,6] as well as in the calculations [7] based on the AV18 NN potential combined with the Urbana IX 3NF.Besides the binding energies of the light nuclei, the importance of the 3NF was experimentally confirmed on the basis of the data originating from the nucleon-deuteron elastic scattering process [8][9][10][11][12][13][14][15][16][17]. In general, inclusion of the 3NF component improves the description of the cross-sectional data. However, quite significant discrepancies between the theoretical models and polarization observables are still present. Exploration of the nucleon-deuteron breakup can be considered as a natural next step in the...

Investigation of the Three-Nucleon System Dynamics in the Deuteron–Proton Breakup Reaction

“…The vector and tensor analyzing power data were measured in 90 geometries for each of the tensor and vector analyzing powers [14] with the SALAD detector. Moreover, measurements with BINA and GeWall delivered additional sets of data for vector analyzing powers at deuteron beam energies of 100 MeV [13] and 130 MeV [12], respectively.…”

“…The 1 H (d, pp)n breakup reactions were studied in different phase-space regions with the use of three detection systems: the SALAD [10] and BINA [11] at KVI and the Germanium Wall (GeWall) [12] at FZ-Jülich. Results of the analyzing powers were obtained with the BINA and SALAD detectors at polarized deuteron beam energies of 100 [13] and 130 MeV [14], respectively.…”

Systematic Studies of the Three-nucleon System Dynamics in the Deutron–Proton Breakup Reaction

“…In case of the tensor analyzing powers certain discrepancies are observed. These problems remain, even if 3NF effects and Coulomb interactions are included in the calculations [7,11]. …”

Experimental Studies of Few-nucleon Systems at Intermediate Energies

“…The significance of 3NF for a correct description of the differential cross section has been confirmed [33,34]. Moreover, deuteron vector analyzing powers of the breakup reaction at 100 and 130 MeV are equally insensitive to any additional dynamics beyond the pure NN interactions as it was observed in the d-p elastic scattering at the same energies [35,36]. On the other hand side, for the tensor analyzing powers of the breakup reaction at the same beam energies, locally certain discrepancies are observed [35], even if (or when) 3NF is included into calculations.…”