Proton polarization in reaction of deuteron photodisintegration at energies of 0.2-2.4 GeV

The review of the proton polarization experimental data on two-body deuteron photodisintegration at a photon energy between 0.2 and 2.4 GeV is presented. The NSC KIPT data are compared with the measurements of other centers and with theoretical calculations and phenomenological analysis in the framework of various interaction models with subnuclear (nucleons, mesons, resonances) and non-nucleon (quarks, gluons) degrees of freedom. The NSC KIPT measurements are in full accord with the data of other centers up to 0.8 GeV and confirm the dominant contribution of meson-exchange interactions and isobar configurations in the reaction γD→pn. Above 1 GeV the NSC KIPT data do not agree with the Jefferson Lab (USA) measurements which confirm the quark-gluon hypotheses about zero values of the proton polarization in this region

Proton polarization in photodisintegration of nuclei D, ³He, ⁴He

The result of proton polarization measurements (period 1993-2000) in the photodisintegration of the nuclei D, ³He, ⁴He at the photon energies E=350-750 MeV are presented. The proton polarization was measured on the 2 GeV linac NSC KIPT with a carbon polarimeter and a magnetic spectrometer. The proton polarization for the nuclei ³He and ⁴He is first measured and analyzed within the framework of "quasi-deuteron" model

Method of proton polarization measurements in investigations of photon interaction with nucleons and nuclei at 2 GeV linac (NSC KIPT)

The method used for proton polarization measurements and the equipment for investigations of the photon interaction with nucleons and nuclei of intermediate energies at the 2 GeV linear electron accelerator (NSC KIPT) is described. The characteristics of key elements of the equipment (magnetic spectrometer, carbon polarimeter with the track registration of pC-scattering) are given. The main results of the proton polarization measurements in the reactions γp→pπ⁰, γD→pn, γA→pX are presented.Представлено опис методики вимірювань поляризації протонів та устаткування, яке використовувалося в дослідженні взаємодій фотонів проміжних енергій з нуклонами та ядрами на лінійному прискорювачі електронів 2 ГеВ ННЦ ХФТІ. Надаються характеристики головних елементів устаткування: магнітного спектрометра та вуглецевих поляриметрів з трековою реєстрацією рС-розсіювання. Представлені головні результати вимірювань поляризації протонів в реакціях γp→pπ⁰, γD→pn, γA→pX.Представлено описание методики измерений поляризации протонов и установки, которая применялась в исследованиях взаимодействий фотонов промежуточных энергий с нуклонами и ядрами на линейном ускорителе электронов 2 ГэВ ННЦ ХФТИ. Приводятся характеристики основных элементов установки: магнитного спектрометра и углеродных поляриметров с трековой регистрацией рС-рассеяния. Представлены основные результаты измерений поляризации протонов в реакциях γp→pπ⁰, γD→pn, γA→pX

Pion photoproduction on the nucleon in the quark model

We present a detailed quark-model study of pion photoproduction within the effective Lagrangian approach. Cross sections and single-polarization observables are investigated for the four charge channels, $\gamma p\to \pi^+ n$, $\gamma n\to \pi^- p$, $\gamma p\to \pi^0 p$, and $\gamma n\to \pi^0 n$. Leaving the $\pi N\Delta$ coupling strength to be a free parameter, we obtain a reasonably consistent description of these four channels from threshold to the first resonance region. Within this effective Lagrangian approach, strongly constrainted by the quark model, we consider the issue of double-counting which may occur if additional {\it t}-channel contributions are included.Comment: Revtex, 35 pages, 16 eps figures; version to appear on PR