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  Proton diffraction scattering on nuclei and nuclear matter distributions.

      The 1 GeV proton scattering from nuclei has been proven to be a very useful tool for studying the nuclear structure. The first high precision measurements of the differential cross sections for elastic scattering of the 1 GeV protons on nuclei were performed at PNPI (LNPI) in 1972. It was demonstrated that with this method one can obtain information on the nuclear matter distributions with the accuracy comparable to that reached in studying nuclear charge distributions by the method of electron scattering. A number of nuclei, from 3He to 208Pb, including all doubly magic nuclei, were studied at PNPI. Starting from 1973, similar investigations were performed in joint PNPI-Saclay experiments
(Ep=1 GeV). Thus, the study of diffraction scattering of ~1 GeV protons on nuclei became a new branch of experimental research in nuclear physics, and it is due to these studies that the most accurate information on nuclear matter distributions has been obtained by present.
(For more detail review see article "Proton diffraction scattering on nuclei and nuclear matter distributions" in PNPI report of the High Energy Physics Division "Main Scientific Activities 1971-1996").

  Small-angle diffraction scattering of hadrons on the lightest nuclei.

      A series of experiments at Gatchina, Saclay, Serpukhov and CERN have been performed where small-angle scattering of pions and nucleons on hydrogen, deuterium, and helium nuclei were studied at intermediate and high energy. A dedicated ionization chamber recoil detector IKAR developed at PNPI was the main part of the experimental setup. The advantage of the applied method was a possibility to measure differential cross sections at small momentum transfers with high absolute accuracy of 1-2%. The differential cross sections of elastic scattering and the analyzing powers have been measured. The total cross sections and the ratios of the real to the imaginary parts for the scalar amplitudes of the studied processes have been found. Experimental upper bounds for the nucleon-nucleon (NN) spin-spin amplitudes have been determined. The obtained experimental data are useful in the NN-scattering phase-shift analyses, and in many cases clarify the problem of the dibaryon resonances which are a matter of interest up to now. Also, the measured hadron-nucleus total cross sections permit to get information on the inelastic shadowing corrections to the cross sections calculated in the framework of the Glauber theory.
(For more detail review see article "Elastic diffraction scattering of hadron on the lightest nuclei " in PNPI report of the High Energy Physics Division "Main Scientific Activities 1971-1996").

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Last update on:   by   Svetlana F. Udalova