Three-Nucleon Force Effects in Nucleon Induced Deuteron Breakup: Predictions of Current Models (I)

An extensive study of three-nucleon force effects in the entire phase space of the nucleon-deuteron breakup process, for energies from above the deuteron breakup threshold up to 200 MeV, has been performed. 3N Faddeev equations have been solved rigorously using the modern high precision nucleon-nucleon potentials AV18, CD Bonn, Nijm I, II and Nijm 93, and also adding 3N forces. We compare predictions for cross sections and various polarization observables when NN forces are used alone or when the two pion-exchange Tucson-Melbourne 3NF was combined with each of them. In addition AV18 was combined with the Urbana IX 3NF and CD Bonn with the TM' 3NF, which is a modified version of the TM 3NF, more consistent with chiral symmetry. Large but generally model dependent 3NF effects have been found in certain breakup configurations, especially at the higher energies, both for cross sections and spin observables. These results demonstrate the usefulness of the kinematically complete breakup reaction in testing the proper structure of 3N forces.Comment: 42 pages, 20 ps figures, 2 gif figure

Measurement of the vector analyzing power in elastic electron-proton scattering as a probe of double photon exchange amplitudes

We report the first measurement of the vector analyzing power in inclusive transversely polarized elastic electron-proton scattering at Q^2 = 0.1 (GeV/c)^2 and large scattering angles. This quantity should vanish in the single virtual photon exchange, plane wave impulse approximation for this reaction, and can therefore provide information on double photon exchange amplitudes for electromagnetic interactions with hadronic systems. We find a non-zero value of A=-15.4+/-5.4 ppm. No calculations of this observable for nuclei other than spin 0 have been carried out in these kinematics, and the calculation using the spin orbit interaction from a charged point nucleus of spin 0 cannot describe these data.Comment: 4 pages, 2 figures, submitted to Phys. Rev. Let

Baryon polarization in low-energy unpolarized meson-baryon scattering

We compute the polarization of the final-state baryon, in its rest frame, in low-energy meson--baryon scattering with unpolarized initial state, in Unitarized BChPT. Free parameters are determined by fitting total and differential cross-section data (and spin-asymmetry or polarization data if available) for $pK^-$, $pK^+$ and $p\pi^+$ scattering. We also compare our results with those of leading-order BChPT

Projectile breakup dynamics for 6^{6}Li + 59^{59}Co: kinematical analysis of α\alpha-dd coincidences

A study of the kinematics of the $\alpha$-$d$ coincidences in the $^{6}$Li + $^{59}$Co system at a bombarding energy of $E_{lab} = 29.6$ MeV is presented. With exclusive measurements performed over different angular intervals it is possible to identify the respective contributions of the sequential projectile breakup and direct projectile breakup components. A careful analysis using a semiclassical approach of these processes provides information on both their lifetime and their distance of occurrence with respect to the target. Breakup to the low-lying (near-threshold) continuum is delayed, and happens at large internuclear distances. This suggests that the influence of the projectile breakup on the complete fusion process can be related essentially to direct breakup to the $^6$Li high-lying continuum spectrum. %Comment: Revised version including new Fig.3 and Fig.4 with new CDCC calculations. Accepted for publication at Eur. Phys. Jour. A. 11 pages, 6 figure

Polarized triton scattering from /sup 26/Mg, /sup 27/Al and /sup 28/Si at 17 MeV

Differential-cross-section and analyzing-power angular distributions were measured for 17 MeV tritons elastically scattered from targets of /sup 26/Mg, /sup 27/Al, and /sup 28/Si in the angular range 20 to 160/sup 0/. The experiment was performed at the Los Alamos Scientific Laboratory Van de Graaff facility using the Lamb-shift polarized triton source and the supercube scattering chamber. A pair of detector telescopes with angular resolutions of +-0.4/sup 0/ detected the reaction products, with mass identification and storage performed by an on-line computer. The triton beam intensity available at the target was about 70 nA with a polarization of 0.77. The target thicknesses were about 3 mg/cm/sup 2/, although thinner targets were used for the /sup 27/Al forward-angle data

Analyzing-power formalism for three-body final states

Various relations important for extraction of analyzing powers from data on reactions involving three particles in the final state were derived. Several of the results pertinent for spin-1/2 and spin-1 polarized beams are presented here. These may be used in analysis of the /sup 1/H(d-vector,pp)n reaction. 3 figures. (RWR