E. Bleszynski

Proton polarization observables for the elastic and inelastic scattering of 500 MeV protons from 40Ca and 208Pb

Abstract Measurements for the elastic and inelastic scattering of 500 MeV protons from 40 Ca and 208 Pb at small momentum transfers are reported. The induced proton polarization P and the spin rotation parameter Q were measured for the elastic scattering. The spin rotation parameters D SS ′ , D SL ′ , D LL ′ , d LS ′ and the induced polarization P were measured for transitions to the 3 − (3.37 MeV) and 5 − (4.48 MeV) states in 40 Ca and the 3 − (2.61 MeV) state in 208 Pb. Comparisons of the data with the theoretical calculations were carried out in the framework of nonrelativistic and relativistic approaches. We extracted the spin-up and spin-down channels for the elastic scattering cross sections and found that predictions of the relativistic and nonrelativistic approaches agree well with the spin-up channel data and differ considerably in the spin-down channel.

Some proton spin observables obtained in p-d elastic scattering at 500 and 800 MeV

Abstract Measurements of the spin transfer observables D NN , D SS , and D LS in p + d → p + d at 500 and 800 MeV are reported. In addition we have measured the polarization, P , and the asymmetry A y . The data were taken in the range 0.2 t c ) 2 . Comparison of the observables is made with the predictions of a relativistic multiple scattering model employing the results of a recent phase shift analysis of NN scattering data.

Spin observables in proton deuteron elastic scattering

Some interesting aspects of spin observables in medium energy proton‐deuteron scattering are discussed. It is argued that measurements of spin observables in this reaction can provide new information on the three‐body (contact) interactions. Such an information is not available from measurements of NN observables and can be obtained from the analysis of the 12 amplitudes which describe p‐d elastic scattering. We discuss the sensitivity of the spin observables to such three‐body interactions in the framework of a realistic model in which each of these amplitudes is separated into 1) ‘‘trivial part,’’ involving single and double scattering terms, unambiguously expressible in terms of physical nucleon‐nucleon (NN) scattering amplitudes and 2) the ‘‘nontrivial part’’ which can not be expressed in terms of two‐body interactions, and represents contributions generated by three‐body forces. We find that the agreement between the data and the model predictions is considerably improved when such three‐nucleon inte...

Spin observables in small-angle elastic pd → pd scattering with an L-type deuteron target at 800 MeV

Abstract We have measured spin correlation parameters that describe the elastic scattering of 800 MeV polarized protons from an L-type polarized deuteron target at laboratory angles below 20°. The measured parameters include the correlated analyzing powers A SL , A LL and A NLL and the proton spin-transfer coefficients C 0L,S , C 0L,L , C SL,N , C NL,S , C NL,L and C LL,N . The results are compared with single-scattering predictions based on different phase-shift solutions for the nucleon-nucleon scattering matrix.

Relativistic spin effects and three-body forces in P-D scattering

We analyze the structure of the (3→3)-nucleon amplitude appearing in proton-deuteron elastic scattering amplitude. We calculate that part of the amplitude, which can be unambiguously expressed, through analyticity and unitarity, in terms of physical (2→2)-nucleon amplitudes. By comparing the result with the experimental data on spin observables we find that it is necessary to add extra terms, which must be interpreted as 3-body effects. These 3-body forces, of the type of contact interactions, are also required by the high-energy asymptotics of the amplitudes involved, and can be, to some extent, determined from soft-pion theorems. Much more information on them should become available through systematic analysis of the spin structure of p-d scattering amplitudes.