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Type of Document Dissertation Author Li, Tao Author's Email Address tli1@nd.edu URN etd-04072008-143633 Title Isotopic Dependence of Giant Resonances in the Even-A $^{112-124}$SN Isotopes and the Asymmetry Term in Nuclear Incompressibility Degree Doctor of Philosophy Department Physics Advisory Committee
Advisor Name Title David Leighton Committee Chair Grant Mathews Committee Member Philippe Collon Committee Member Umesh Garg Committee Member Xiaodong Tang Committee Member Keywords
- Symmetry energy
- Nuclear incompressibility
- Giant resonances
Date of Defense 2007-12-14 Availability restricted Abstract We have investigated the isoscalar giant resonances in the even-A Snisotopes (A=112--124) using inelastic scattering of 400-MeV
$alpha$-particles at extremely forward angles, including 0$^circ$,
at the Research Center for Nuclear Physics (RCNP), Osaka University,
Japan. Because of the unique optical properties of the Grand Raiden
magnetic spectrometer, it was possible to obtain inelastic
scattering spectra free of all instrumental background. We are able
to extract strength distributions for various multipoles with
multipole decomposition analysis. Essentially all of expected
isoscalar giant monopole resonance (ISGMR), isoscalar giant dipole
resonance (ISGDR), isoscalar giant quadrupole resonance (ISGQR) and
high energy octupule resonance (HEOR) strengths were identified in
these nuclei. Although the ISGMR has been identified previously in
some of the Sn isotopes in measurements with inelastic
$alpha$-scattering, this is the first time that it has been
investigated in a large number of isotopes simultaneously. We find
that the ISGMR energies in the Sn isotopes are significantly lower
than the values predicted in recent theoretical calculations even
though the interactions used in these calculations reproduce the GMR
energies in the ``standard' nuclei, $^{208}$Pb and $^{90}$Zr, very
well. Further, the asymmetry-term, K$_ au$ , has been determined
to be -550 $pm$ 100 MeV from these measurements.
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