ИЗМЕРЕНИЕ ДИФФЕРЕНЦИАЛЬНОГО СЕЧЕНИЯ И ВЕКТОРНОЙ АНАЛИЗИРУЮЩЕЙ СПОСОБНОСТИ РЕАКЦИИ УПРУГОГО dp-РАССЕЯНИЯ ПРИ ЭНЕРГИИ 2 ГэВ А.А. Терехин, В.В. Глаголев, В.П. Ладыгин, С.М. Ладыгина Объединенный институт ядерных исследований, Дубна, Россия ИТЭФ, 2011

The interest to study dp-elastic scattering at small angles at high energies are defined by the varied reasons. Deuteron is the simplest system which consists of two nucleons. It has spin equal to 1. This feature allows to perform the various polarization experiments. At the same time deuteron has relatively simple structure. It makes possible to test theory of scattering processes. Large values of the analyzing powers allow to use this reaction for the efficient polarimetry of the deuteron beam at MeV. The dp-elastic scattering at small angles at high energies

2  The angular dependence of the vector analyzing power A y and differential cross section for dp-elastic scattering at 2 GeV are reported in this presentation. The data were obtained using 1 m hydrogen bubble chamber at JINR (Dubna).  The results are compared with the data at ANL (Argonne) and with the theoretical calculations based on the relativistic multiple scattering theory.

Losses of the events in the region of small momentum transfers The losses of the events in the region of small momentum transfers appear due to methodical reasons. They are related both with the impossibility to observe the tracks with the momentum less than 80 MeV/c and the tracks orientation in the photo-camera direction.

Example of the R value distribution for the angular interval 12° <θ* <14° in the cms. For each angular interval parameters of the function p 0 + p 1 sin(φ) was determined

5  Evaluation of the vector polarization of an accelerated beam was performed using the events of the reaction dp → ppn. The deuteron beam polarization was estimated as: p y = ± 0.061[1] by the measuring of the azimuthal asymmetry of quasielastic scattering using the data on the analyzing powers for elastic np-and pp-scattering at the corresponding energy Figure 5.Analyzing power for elastic np-and pp-scattering Figure 4. Distribution of events over the azimuthal angle [1] Glagolev V.V. et al. // Z. Phys. A356 (1996) 183.

6 The events obtained both from polarized and unpolarized deuterons beams was used for calculation of the differential cross section. Losses in another reactions were negligible. The millibarn equivalent of the events was estimated as C = ± mb/event [2]. The cross section was calculated using the formula: [2] Bugg D.V. et al. // Phys. Rev. Lett Pp

7 The theoretical predictions have been obtained in the relativistic multiple-scattering-theory frame [3]. The single scattering and double scattering contributions into the reaction amplitude were taken into account. Since ONE term gives considerable contribution only at backward angles, this term was not included into consideration. [3] Ladygina N.B. // Eur. Phys. J. A42 (2009) 91.

8 Solid squares – this work. Empty triangles - data from Bennett G. W. et al. Phys. Rev. Lett V.19 P Differential cross section

9 Empty boxes - this work. The solid circles – data from Bennett G. W. et al. Phys. Rev. Lett V.19 P

Analyzing powers Solid triangles – this work Empty squares - data obtained at ANL.

11 Analyzing powers Empty circles – this work The solid circles - data from M.Haji-Saied et al., Phys.Rev.C 36 (1987) pp Empty squares - from P.K. Kurilkin et al., Int.J.Mod.Phys. A24: , 2009.

Conclusion  Vector analyzing power Ay and differential cross-section of dp-elastic scattering at the deuteron energy 2.0 GeV and at the scattering angles in the cms were obtained.  The results agree with experimental data at Argonne (ANL) and with the calculations of multiple scattering theory taking into account the double scattering.

13 Thank you for attention

14 False asymmetry The value of p 0 doesn’t exceed 5% and is equal to p0 = 

15 Events losses for the elastic dp-scattering in the t-distribution