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29 MeV elastic scattering differential cross section ratio of 12C/13C

University of British Columbia

The large fluxes of positive and negative pions available in meson factories over the last few years have lead to an accumulation of precise n-nuclear data over wide ranges in energy and atomic number. Little nuclear structure information has been extracted from the data since a microscopic model for the pion interaction in the nucleus is not fully developed. However the elastic scattering differential cross sections for. low energy pions are predicted well over a wide range of atomic mass using a potential in which some parameters are empirically derived., since the potential is semi-empirical some nuclear structure information can not reliably be derived directly from the data. Measurement of differences in the nuclear structure between neighbouring nuclides, however, should be reliable if the potential produces the correct variation of differential cross section in this mass region. In the experiment reported here the differential cross section ratio for elastic scattering of 29 MeV π- on ¹³C/¹²C is measured using scintillator range telescopes. Solid carbon targets of pressed powder were used. Since a relative measurement is made the errors in the ratio are only statistical. A large peak in the distribution of the cross section ratio is produced by changes in the s-p interference minimum between ¹²C and ¹³C. The cross section ratio is sensitive to the neutron distribution of ¹³C because of the large s-wave interaction of the pion with neutrons in the nucleus. A measurement of the neutron rms. radius of ¹³C and some tests of dependence on the shape of the neutron distribution and optical potential parameters are made. The neutron distribution rms. radius of ¹³C is found to be 2.365±.025 fm.

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2010-03-02

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http://hdl.handle.net/2429/21360

Physics

University of British Columbia

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