S. I. Trush

Polarization effects in the quasielastic (p, 2p) reaction with the nuclear S-Shell Protons at 1 GeV

The polarization of the secondary protons in the (p, 2p) reaction with the S-shell protons of nuclei 4He, 6Li, 12C, 28Si, 40Ca was measured at 1 GeV unpolarized proton beam. The spin correlation parameters Cij for the 4He and 12C targets also were for the first time obtained as well. The polarization measurements were performed by means of a two-arm magnetic spectrometer, each arm of which was equipped with the multiwire-proportional chamber polarimeter. This experiment was aimed to study a modification of the proton-proton scattering matrix in the nuclear medium.

Polarization in quasielastic (p, 2p) scattering on a 4He nucleus at 1 GeV

The polarization of secondary protons from the (p, 2p) reaction induced by 1-GeV protons incident to a 4He nucleus was measured in a kinematically complete experiment. By using a two-arm magnetic spectrometer, two secondary protons from this reaction were recorded in coincidence at unequal scattering angles of Θ1 = 18°−24.21° and Θ2 = 53.22° over a broad range of the recoil-nucleus momentum KB between 0 and 150 MeV/c. It was found that the measured polarization of either secondary proton is less than that observed in free elastic proton-proton scattering. The magnitude of this difference is determined by the mean binding energy of s-shell protons rather than by the effective nuclear density. The polarizations measured in inclusive quasielastic and elastic scattering of 1-GeV protons on 4He nuclei are presented for scattering angles in the range Θ1 = 18° − 24.21°.

Measurement of the polarization correlation parameter Cnn in the pp elastic scattering with an unpolarized proton target and an unpolarized 1-GeV proton beam

The polarization correlation parameter Cnn in the elastic proton-proton scattering was for the first time measured with a high statistical accuracy at 1 GeV using an unpolarized proton beam incident on an unpolarized proton target. Both outgoing protons from the reaction were detected in coincidence by means of a two-arm focusing magnetic spectrometer installed at nonsymmetric angles corresponding to the center-of-mass scattering angle Θcm = 62.25°. The correlation parameter Cnn, as well as polarizations P1 and P2 of the secondary protons, were measured by means of multiwire proportional chamber polarimeters placed at the focal planes of each spectrometer arm. The obtained data are compared with the predictions of the phase-shift analysis. The connection with the experiment on Cnn and polarization measurements in the (p, 2p) reaction on 4He and other light nuclei in similar kinematics is discussed

Polarizations for 12C(p, 2p) Reactions at 1 GeV

We have measured polarizations P of outgoing protons in (p, 2p) reactions at an incident energy of 1 GeV for three kinds of targets. The experimental result shows a distinct reduction from IA calculation values using NN interaction in free space and the reduction is found to be monotonic to the effective mean density estimated with DWIA. This is consistent with the previous result obtained at 392 MeV, though the incident energy is quite different. We have also measured an angular distribution of the polarization for 12C target. All of the data, including both for forward nd backward outgoing protons, show similar reduction from the IA calculation, though, again, outgoing energies are quite different from 130 MeV to 890 MeV. From these results, it is concluded that these reductions are nuclear structure or interaction originated and not caused by the reaction mechanism such as multi‐step processes or distortions.

Study of nuclear medium effect on hadrons in nuclei by nucleon quasifree scattering

Polarizations of outgoing two protons in (p,2p) reactions leading to either 1s1/2 or 2s1/2 deep hole state have been measured at an incident energy of 1 GeV. The result shows distinct reduction from calculated values using NN interaction in free space and the reduction is found to be monotonic function of the mean density estimated with DWIA. Those are consistent with results at 392 MeV. From these result, it is concluded that these reductions are nuclear structure or interaction originated and not caused by reaction mechanism such as contribution of two step processes.