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 270-2000 MeV.

The dp-elastic scattering at small angles at high energies

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The angular dependence of the vector analyzing power Ay 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.

yy p

pA 1

3

2

21

21

NN

NNR

Example of the R value distribution for the angular interval 12° <θ* <14° in the cms.

For each angular interval parameters of

the function p0 + p1sin(φ) was determined

spinN

spinN

2

1

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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: py = 0.488 ± 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.

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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 =

0.0003342 ± 0.0000007mb/event [2]. The cross section was

calculated using the formula:

[2] Bugg D.V. et al. // Phys. Rev. Lett. - 1996. - 146. - Pp. 980-992.

*cos)(cos

2

1 *

С

Nd

d

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• 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.

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Solid squares – this work.

Empty triangles - data from Bennett G. W. et al. Phys. Rev. Lett. 1976. V.19 P. 387-390.

Differential cross section

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Differential cross section

Empty boxes - this work.

The solid circles – data from Bennett G. W. et al. Phys. Rev. Lett. 1976. V.19 P. 387-390.

Analyzing powers

Solid triangles – this work

Empty squares - data obtained at ANL.

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Analyzing powers

Empty circles – this work The solid circles - data from M.Haji-Saied et al., Phys.Rev.C 36 (1987) pp.2010-2017. Empty squares - from P.K. Kurilkin et al., Int.J.Mod.Phys. A24:530-533, 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 100-350 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.

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Thank you for attention

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False asymmetry

• The value of p0 doesn’t exceed 5% and is equal to p0 = -0.025 0.014.

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