Influence of the Mott-Schwinger interaction on the elastic scattering of protons

It is demonstrated that the Mott-Schwinger interaction must be taken into account when analyses of polarisation measurements in proton scattering at energies below the Coulomb barrier are to be performed with high accuracy. A treatment of the effect is worked out in perturbation theory, and the reliability of the method is demonstrated. It is shown how the resulting badly converging series for the “Mott-Schwinger amplitude” can conveniently be summed by means of Padé-approximation. Numerical results are presented for several representative cases.     

2-jet production in polarised\vec p\vec pcollisions

Following recent interest in the subject of polarisation phenomena, we discuss the cross-sections and polarisation asymmetry in 2-jet production in polarised proton-polarised proton ( ) scattering. We set up a complete set of parametrisations for the proton spin-dependent parton densities and use them to demonstrate that this cross-section is dominated by gluonic terms. Hence, a measurement of the asymmetry in such processes will provide information on the gluon spin-dependent density. We further show that a factorisation of the hadronic cross-section a la Combridge and Maxwell's work in unpolarised 2-jet production also applies to the spin-dependent case. Hence, the cross-section can be written in terms of a genericpolarised parton density, which can then be measured in the process.     

Studying the possibility of recovering np and nn helicity amplitudes on the basis of \vec p + \vec d and \vec n + \vec d scattering data at intermediate energies

In this work, we study the possibility of direct recovery of np helicity amplitudes, which are unknown at incident neutron energies T _n > 1.1 GeV, and nn helicity amplitudes, which are unknown at any energy, from data on $\vec p + \vec d$ and $\vec n + \vec d$ scattering. For the inversion of $\vec N + \vec d$ data, we use formulas that relate N _d- and NN amplitudes derived in terms of a refined Glauber model. It is found that the critical factors for solving the inverse problem under study are the accuracy and completeness of the set of input $\vec N + \vec d$ observables.     

Exchange interaction and elastic 16O + 12C scattering

The effect of core exchange on the potential of interaction between the ¹⁶O and ¹²C nuclei is considered. The amplitudes corresponding to nonlocal exchange interactions are calculated in the Born approximation. It is shown that the inclusion of exchange processes leads to the growth of the elasticscattering amplitude in in the region of large scattering angles. The dependence of amplitudes on the parity of relative motion is analyzed.     

Levels in 13N examined by 12C p elastic resonance scattering with thick target

The elastic resonance scattering of 12C p has been studied in inverse kinematics via a novel thick target method at GIRAFFE facility of HI-13 tandem accelerator laboratory, Beijing. The recoil protons were measured by a △E-E counter telescope based on a large area double-sided silicon strip detector at laboratory angles around θ0 = 15°. The excitation function for 12C(p,p) elastic scattering has been obtained over a wide energy range of Ec.m.=0.31—3.45 MeV, which was explained quite well by the R-matrix calculation with known resonance parameters of the first three levels in 13N nucleus. Thus it is demonstrated that the present setup can be directly applied to the study of elastic resonance scattering with secondary radioactive beams.     

The\overrightarrow p - Si elastic scattering in the region of giant multipole resonances

Analyzing powers and cross sections for the scattering of polarized protons from Si have been measured at eight energies between 17 and 29MeV. The analysing powers show an “anomalous” behaviour and an optical model analysis yields a non-monotonic effect in the spin-orbit potential.     

First measurement of the polarisation transfer on the proton in the reactionsH(\vec e,e'\vec p) andD(\vec e,e'\vec p)

The measurement of the polarisation transfer to the proton in the reactions $H(\vec e,e'\vec p)$ and $D(\vec e,e'\vec p)$ performed with longitudinally polarised electrons in quasi-free kinematics is presented. The coincidence measurement was executed atQ ²≈8fm ^?2 using the 855 MeV, c.w. beam of the Mainz Microtron MAMI. The recoil polarisation was determined by means of a carbon analyser. The experiment shows that the binding of the nucleon does not modify the polarisationP _x of the recoil proton within an error ofΔ P _x/P_x≈10%. The measured polarisation agrees with recent theoretical predictions. Implications for the measurement of the electric form factor of the neutron using the $D(\vec e,e'\vec n)$ reaction are discussed.     

Phase shift analysis of elastic proton scattering by12C

Angular distributions of the polarization and cross section in¹²C (p,p)¹²C were measured at 24 energies between 9.95 and 10.90 MeV. A phase shift analysis of the data was carried out. The results show four resonances in¹³N atE _x =11.40, 11.64, 11.67 and 11.82 MeV with spins 5/2⁺, 5/2^?, 3/2^? and 3/2⁺.     

Angular Dependence of the Polarization Transfer to the Proton in the $$e\vec {p} \to e\vec {p}$$ Process

JETP Letters - The dependence of the longitudinal polarization transfer to the proton in the $$e\vec {p} \to e\vec {p}$$ process on the proton scattering angle has been numerically analyzed for the...     

Levels in 13N examined by 12C+p elastic resonance scattering with thick target

The elastic resonance scattering of 12C+p has been studied in inverse kinematics via a novel thick target method at GIRAFFE facility of HI-13 tandem accelerator laboratory,Beijing.The recoil protons were measured by a △E-E counter telescope based on a large area double-sided silicon strip detector at laboratory angles around θ0=15°.The excitation function for 12C(p,p)elastic scattering has been obtained over a wide energy range of Ec.m.=0.31-3.45 MeV,which was explained quite well by the R-matrix calculation with known resonance parameters of the first three levels in 13N nucleus.Thus it is demonstrated that the present setup can be directly applied to the study of elastic resonance scattering with secondary radioactive beams.     

Ranges of interaction inp\bar p scattering at low energies

Thep¯ p cross sections at low energies are analysed in the framework of the optical model. It is shown that the annihilation range is closely related to the size of the proton as measured in electromagnetic and hadronic interactions. At larger distances thep¯ p interaction has the similar character as the NN one.     

Pomeron and odderon in high energypp andp\bar p elastic scattering

High energypp and data on elastic scattering and total cross sections are analyzed in a model including the pomeron, odderon and secondary reggeons. A dipole model is used for the pomeron and for the odderon. By construction, our (bare) pomeron ansatz produces a single dip, as observed experimentally. The model reproduces the logarithmically rising cross sections with a unit pomeron intercept, but better fits are obained when a small non-zero value of the parameter = _p (0) is allowed for. Predictions for the future accelerators (UNK, LHC, SSC) are given.On leave of absence from the Institute for Theoretical Physics, Kiev-130, USSR     

Analyzing powers in the 12C( \vec d ,p)13C reaction at the energy T d = 270 MeV

The preliminary results on the tensor T₂₀ analyzing power for the ¹²C(,p)¹³C* reaction with the excitation of ¹³C levels and the d(,p)X reaction at the energies T _d = 140, 200 and 270 MeV at the emission angle Θ _cm = 0° are presented. The data on the tensor A _yy and vector A _y analyzing powers for the ¹²C(,p)¹³C* reaction at the energy T _d = 270 MeV in the angular range from 4° to 18° in the laboratory are also obtained.     

On the Transfer of Polarization from the Initial to the Final Proton in the Elastic Process $$e\vec {p} \to e\vec {p}$$

JETP Letters - The $${{Q}^{2}}$$ dependence of the ratio of the cross sections with and without spin flip, as well as the polarization asymmetry in the $$e\vec {p} \to e\vec {p}$$ process, has been...     

Energy dependence of heavy ion collisions 4He + 12C and 12C + 12C elastic scattering

We have studied the transparency of heavy ion collisions at high energies by using Glauber's multiple scattering theory. The good agreement between our calculation and the existing data available strongly emphasizes the dominance of the nucleon-nucleon interaction in nucleus-nucleus collisions at high energies.     

Investigation of condensed matter by means of elastic thermal-neutron scattering

The application of elastic thermal-neutron scattering in investigations of condensed matter that were performed at the Institute for Theoretical and Experimental Physics is described. An account of diffraction studies with weakly absorbing crystals, including studies of the anomalous-absorption effect and coherent effects in diffuse scattering, is given. Particular attention is given to exposing the method of multiple small-angle neutron scattering (MSANS). It is shown how information about matter inhomogeneities can be obtained by this method on the basis of Molière’s theory. Prospects of the development of this method are outlined, and MSANS theory is formulated for a high concentration of matter inhomogeneities.     

Neutrino oscillation and magnetic moment from \nu - e^{-} elastic scattering

We discuss how the measurement of the elastic cross section at reactor energies can be used to extract new information on the neutrino oscillation parameters. We also consider the magnetic moment contribution and show how both effects tend to cancel each other when the total cross section is measured. To achieve the separation of each of the effects, experiments capable of measuring angular and energy distributions with respect to the outgoing electron become necessary. The sensitivity of these kind of experiments to magnetic moments, masses and mixings is discussed. We also discuss the possibility of measuring the magnetic moment of neutrinos via oscillation. Received: 12 September 1997 / Revised version: 22 December 1997 / Published online: 10 March 1998