Deuteron elastic scattering cross sections have been measured at 110 and 120 MeV on C, Ni, and Pb. Optical model potentials have been extracted and compared to deuteron global optical model potentials. PACS number(s): 24.10.Ht, 25.45.De, 27.20.+n, 27.40.+z We have measured deuteron elastic scattering cross
We have measured cross sections for (d, He) induced reactions on the p-shell nuclei Li, ' C, and ' C and the sd-shell nucleus Mg at an energy of Ed=125.2 MeV. The measured excitation energy spectra are very similar to those from (p, nl, (n, p), and (d, He) reactions at higher energies. The measured 0' (d, He) cross sections show a remarkably well-defined linear relation with the Gamow-Teller strengths deduced either from P decay or from (p, n) reactions. Our results demonstrate that the (d, He) reaction can be used as a powerful tool to study Gamow-Teller strengths in the P+ direction at energies as low as Ed=125.2 MeV.
A precision measurement of spin transfer in pp elastic scattering at 197.8 MeV has been completed recently at the Indiana University Cyclotron Facility. The new data span a kinematic regime chosen specifically to maximize sensitivity to the neutral pNN coupling constant. Our results provide strong support for modern potential models of the NN interaction in which a relatively weak pion coupling (g 2 0 ഠ 13.6, f 2 0 ഠ 0.075) is employed, but disagree significantly with predictions of older models in which g 2 0 ഠ 14.4. Calculations in a one-boson-exchange framework indicate that most of these latter differences can be removed by reducing g 2 0 from 14.4 to 13.6 in these models. PACS numbers: 13.75.Cs, 21.30.Cb, 25.10. + sWhile quantum chromodynamics (QCD) is widely regarded as the underlying theory of the strong interaction, our best quantitative descriptions of most low and intermediate energy nuclear phenomena are still provided by effective theories of the interaction, in which baryons and mesons serve as efficient, collective degrees of freedom. Thus, there is great interest in determining precisely the values of the constants that appear, for example, in mesonbased models of the NN interaction. In these models, the one-pion-exchange process plays a fundamental role, dominating the long-range hadronic force, especially the tensor terms, with a strength determined primarily by the size of g 2 p , the pNN coupling constant [1]. Accurate knowledge of this coupling strength is therefore crucial for predictions of NN and pN scattering behavior and deuteron ground-state properties, or in descriptions of the NN interaction that serve as input to microscopic nuclear reaction or structure models. The strength of g 2 p also plays a critical role in testing low-energy theorems of charged pion photo-or leptoproduction, and allows one to gauge the extent to which chiral-symmetry breaking is present in the pN interaction via the Goldberger-Treiman discrepancy [2].Thus, it was quite a surprise a few years ago when new determinations of both the neutral [3] and charged [4] pion coupling constants, g 2 0 and g 2 c , based largely on global analyses of pp and pN scattering data, respectively, yielded values in striking disagreement with previous determinations and favoring much weaker couplings. The new couplings also appeared to be incompatible with the strengths required in meson-exchange models to produce the correct deuteron quadrupole moment and asymptotic D͞S state ratio [5], and with values for g 2 c recently extracted from back-angle np cross section data [6,7]. These concerns have been described at length in the literature (see, for example, [8,9]), and will not be discussed further here. It is clear, though, that many of the most contentious issues hinge on the reliability, reproducibility, or indeed the availability of data for particular sets of observables in the most critical regions of momentum transfer.Such thinking led us to investigate the sensitivity of g 2 p to various subsets of the NN database. We have sho...
We propose a model-independent method to extract a linear combination of the s-wave p-p scattering lengths by measuring the gg decay branching ratio for a tagged sample of p 1 p 2 atoms (pionium). In the first experimental search for an appropriate tagging reaction, we observed s tot 76 6 21 6 11 pb for free pion pair production in pd ! 3 Hep 1 p 2 1.0 MeV above threshold. This result suggests a pionium production cross section &1 pb. [S0031-9007(96)01416-0]
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