T-violation effects in (n,d) elastic scattering

TheT-violation effects in neutron-deuteron scattering caused byT-noninvariantP-even nucleon-nucleon interaction are discussed.     

Microscopic description of low-energy neutron scattering by nuclei

The Bloch and Gillet shell-model formalism extended to continuum states is applied to lowenergy neutron scattering by nuclei. It is shown that complete antisymmetrization leads in the r-representation to corrective terms which yield important corrections to the scattering lengths. Calculations are performed within a model restricted configuration space for the target nuclei ¹²C, ¹³C, ¹⁶O, ¹⁷O and ⁴⁰Ca. We predict values for the spin-dependent scattering amplitude for ¹³C and ¹⁷O. The antisymmetrization problem in the case of a large configuration mixing is studied for the ¹⁹F target nucleus. The resonant effects of the compound nucleus are then very important and the results become very sensitive to the configuration space and the interaction parameters.     

Dispersive treatment of low-energy pion-nucleus forward elastic scattering

The amplitudes for pion-nucleus forward elastic scattering are studied by means of dispersion relations, with emphasis on the low-energy and unphysical regions. The importance of the threshold behaviour of inelastic pion scattering is pointed out, and effective coupling constants, a news-wave parameter and the real part of thep-wave scattering length are determined.     

Spin-asymmetry in elastic scattering of low-energy electrons from ultrathin Au films on W(110)

We present joint experimental and theoretical results on the elastic scattering of spin-polarized electrons from an epitaxial Au film on a W(110) substrate in the energy range from 8 eV to 27 eV. A time-of-flight technique with a position-sensitive detector is applied to measure secondary emission spectra for spin-up and spin-down primary electrons in a specular geometry. The spin-asymmetry of coherently scattered electrons is obtained by selecting the diffraction spot on the detector. Regions of large asymmetries – with a maximum of about ?60 % – are identified for electron energies of about 14 eV. Relativistic multiple-scattering calculations produce spin-orbit-induced asymmetries which are in agreement with their experimental counterparts. They further reveal that large asymmetries are associated with high intensities. This offers the possibility of an efficient new spin polarimeter with a figure of merit of about 1.5 · 10^?2.     

Microscopic description of low-energy neutron scattering on a deuteron

Low-energy neutron-deuteron scattering is calculated within the collective adiabatic approach by using a few versions of realistic NN interaction. The resulting integrated cross sections for the process are in good agreement with experimental data.     

Isospin breaking in low-energy charged pion–kaon elastic scattering

We use chiral perturbation theory to evaluate the scattering amplitude for the process at leading and next-to-leading orders in the chiral counting and in the presence of isospin breaking effects. We also discuss the influence of the latter on the combination of the -wave scattering lengths which is relevant for the 2S–2P energy level shift of atoms. Received: 19 November 2001 / Revised version: 21 December 2001 / Published online: 5 April 2002     

Parity non-conservation effects in neutron elastic scattering reactions

Energy dependence of parity non-conservation effects is derived for neutron elastic scattering on nuclei: emission asymmetry and the rotation of the polarization plane for the polarized neutron beam and longitudinal polarization for unpolarized neutrons. Both potential scattering and scattering through the compound-nucleus resonances (multi-level approximation) are taken into account. The expressions obtained are compared with experimental data on thermal neutron scattering.     

First observation of nuclear rainbow scattering in 16O + 40Ca system

Measurements of the differential cross section of the ¹⁶O + ⁴⁰Ca elastic scattering at the ¹⁶O energy 214 MeV were performed. For the first time, nuclear rainbow scattering in the ¹⁶O + ⁴⁰Ca system was observed. The analysis shows that the 45° minimum in the angular distribution could be identified as an Airy supernumerary one, probably, of the third order. It corresponds to a distance of closest approach of the colliding nuclei less than 3 fm. The text was submitted by the authors in English.     

The reactiond+d→p+t and elastic deuteron-deuteron scattering at 51.5 Mev

The elastic deuteron-deuteron scattering and the reactionsd(d,p)t andd(d,³He)n have been investigated at an incident deuteron energy of 51.5 MeV. Time-of-flight technique was used for the particle identification. The observed angular distributions for the (d, p) and (d, n) reaction are identical within the accuracy of the experimental data. The experimental results for the reactiond(d, p)t are compared with a theoretical prediction based on the application of a generalized separable potential model to the four nucleon systems. Information on the single deuteron break-up reactiond+d→d+p+n and on the double deuteron break-up reactiond+d→p+p+n+n is contained in the observed continuous proton and deuteron spectra. The double break-up seems to be contribute only with a rather small amount to the whole break-up cross section.     

Determination of adsorbate orientation from symmetry rules in low-energy elastic electron scattering

In this Letter we describe a particular elastic-scattering experiment which is simple to perform and which establishes a connection between the scattering pattern and the orientation of a molecule adsorbed on a solid surface. This approach is illustrated by examining the cases of CO and C₂H₄.     

A global optical-model analysis of neutron elastic scattering data

Differential cross sections for neutron elastic scattering in the energy range 7–26 MeV from ⁴⁰Ca, ⁹⁰Zr, ⁹²Mo, ^{116, 124}Sn and ²⁰⁸Pb are analyzed in terms of a global optical-model potential. A smooth variation of the real radius parameters with mass number is investigated. Otherwise, optical-model geometrical parameters are kept fixed at values obtained by averaging individual best fits. The energy and isospin dependences of potential strengths and volume integrals per nucleon are presented.     

Molecular scattering states of the neutron in the elastic scattering of C on C

The angular distributions of elastic scattering of ¹²C on ¹³C at 15 MeV and 19 MeV (Lab) have been remeasured in the full angular range using a magnetic spectrometer. The analysis of the data based on the method of molecular wave functions is discussed using the two center shell model (TCSM) and linear combination of nuclear orbitals (LCNO) approaches for the scattering states of the neutron.