L. S. Azhgirey

Nuclear interactions of 660 MeV protons and the momentum distribution of nucleons in nuclei

An investigation is carried out of the angular distributions and, by magnetic analysis, of the energy spectra of secondary charged particles (mainly protons with energies ⪆ 60 MeV)emitted at angles of 7°, 12.2°, 18°, 24° and 30° in interactions of 660 MeV protons with nuclei of Be, C, Cu and U. The cross sections for emission of such secondary charged particles increase with decrease of the angles. In the order of decreasing energy the various spectral regions of all investigated elements corresponds to diffraction scattering of protons on nuclei (in the small angle region), single quasi-elastic proton-nucleon collisions, π-mesons production on bound nucleons and nuclear cascade. The experimental energy spectra for single quasi-elastic proton-nuclear scattering are compared with the spectra computed in the impulse approximation under various assumptions regarding the momentum distributions of the nucleons in the nuclei. The Be and C data are consistent with a Gaussian nucleon momentum distribution falling to 1/e at an energy of approximately 20 MeV. This means that the mean square value of the nucleon momentum in Be and C nuclei corresponds to an energy of ≈ 30 MeV.

Fragmentation of 9 GeV/c deuterons in the region of proton transverse-momenta of 0.5-1 GeV/c and the deuteron wave-function at small distances

Abstract Momentum spectra of protons emitted at angles of 0.103, 0.139 and 0.157 rad in fragmentation of 9 GeV/ c deuterons on 1 H, 2 H and 12 C nuclei have been measured at the JINR synchrophasotron by using a magnetic spectrometer. It is found that the shape of the high-momentum parts of the spectra is defined only by the deuteron structure and the mechanism of deuteron-nucleon interaction and does not depend on a target. The contributions to the differential cross section of the 1 H(d, p)X reaction have been determined, which are conditioned by elastic and inelastic scatterings of deuteron nucleons on a proton, stripping, their interference, and also the excitation of the pion degrees of freedom. In the framework of the light front dynamics, calculations of the proton spectra with the deuteron structure functions for the Paris, Reid soft core, and Bonn potentials have been performed; a better agreement with the experiment is achieved with the deuteron wave function for the Paris potential. A conclusion is made that the nucleons in a deuteron keep their individuality up to relative motion momenta of ∼ 1 GeV/ c .

Possible interpretation of the „anomalous“ behaviour of the proton spectrum at 0° from the deuteron fragmentation at 9 GeV/c

The momentum spectra of protons, produced at 0° as a result of fragmentation of relativistic deuterons on nuclei, are analyzed. Possible causes of the existing discrepancy of the data on the 0° proton spectrum from the1H(d,p)X reaction at 9.1 GeV/c with results of the impulse approximation calculations are considered. It is shown that taking into account the finite angular resolution of the experimental setup and the corresponding renormalization of the experimental data, on the one hand, and also the inclusion of the additional (to stripping) contribution of protons from the scattering of deuteron nucleons by target protons, on the other, make it possible to match these data with the results of calculations within the framework of the relativistic impulse approximation using the deuteron wave function for the Paris potential.

Small-angle elastic scattering of protons on carbon nuclei at 660 MeV

Abstract The differential cross sections for the elastic scattering of protons by carbon nuclei and the proton polarization in this process have been measured in the interval1.8° ≦ θ ≦ 9° at 660 MeV. Using a magnetic analysis, elastic proton scattering was separated from inelastic scattering. The best values of the real and imaginary parts of the spin-independent and spin-dependent forward scattering amplitudes have been found to be g NR (0) = −5.05±0.45 fm , g NI (0) = 15.26±0.45 fm h NR (0) = −10.4±13.3 fm , h NI (0) = 37.6±9.3 fm . The values of the integrated optical potentials have been given. The values of r.m.s. radii for the central and spin-orbit potentials have been deduced to be equal to 2.48±0.04 fm and 2.83±0.16 fm. The spin-orbit interaction at 660 MeV is found to be smaller than that at 310 MeV. Conclusions are drawn on the complex value of the spin-orbit potential of the nucleon-nucleus interaction at 660 MeV.

The structure of the high-momentum parts of the deuteron spectra from d-d collisions at 4.3, 6.3 and 8.9 GeV/c

Abstract The experimental data on d-d collisions at 4.3, 6.3 and 8.9 GeV/ c , exhibiting the two-peak structure in the high-momentum parts of the secondary deuteron spectra at momentum transfers | t | ≈ 0.4–0.8 (GeV/ c ) 2 , are presented. An analysis of the results in terms of the multiple nucleon-nucleon scattering model is given. Some conclusions about the mechanism of the elastic and quasielastic d-d scattering at the above-mentioned momentum transfers are made.

Proton spectra from 6.3 GeV/c deuteron break-up on 1H, 2H, C, A1 and Bi nuclei

Abstract The proton spectra resulting from 6.3 GeV/ c deuteron break-up on 1 H, 2 H, C, Al and Bi nuclei were measured at an angle of 103 mr (lab) in the momentum interval from 2.6 to 3.6 GeV/ c . The measurements were made at the JINR synchrophasotron with a one-arm magnetic spectrometer on-line with a computer. The results, apart from the effects of pion production, are reasonably reproduced in the framework of the Glauber multiple scattering model, taking into account the relativistic deformation of the deuteron wave function.

Fragmentation of 6.3 GeV/c deuterons on h,d,c,al, and bi nuclei

The momentum spectrum of protons emitted in the reaction d + A ..-->.. p + X at 6.3 GeV/c with hydrogen, deuterium, carbon, aluminum, and bismuth is presented. The measured spectra are shown, and the differential cross section calculated. 5 references. (JFP)

Elastic and quasielastic d‐d scattering at 4.3, 6.3 and 8.9 GeV/c

A two-peaked structure from previous work is studied in the deuteron momentum spectrum in the process d + d ..-->.. d + X at 4.3 to 8.9 GeV/c. It is concluded that the elastic deuteron scattering at momentum transfers approx. 0.3 to 1.0 (GeV/c)/sup 2/ occurs in the main through such double scatterings when in simultaneous collisions both the nucleons of the incident deuteron scatter each on one of the two target nucleons. Such a mechanism permits rather a great momentum to both the deuteron nucleon to be transferred without disturbing their relative intranuclear motion. 7 references. (JFP)