Fragment Angular Anisotropies for Magic and Non-Magic Nuclei

ORAL

Abstract

Fission fragment angular distributions have been studied for $^{239} {Pu} (n, f)$ reaction at several neutron energies. Theoretical calculations have been utilized to determine the variance $K_{0}^{2}$ at each bombarding energy from the observed angular anisotropies. The values of $K_{0}^{2}$ show sharp rise from a value of 5-6 to about 13 for higher neutron energies. From the position of one of the breaks in the $K_{0}^{2}$ value, the magnitude of the pairing gap $2\Delta$ in the highly deformed transition nucleus $^{240} Pu$ is estimated to be 2.4 MeV. Fission fragment angular anisotropies from changed particle fission of $^{208} Pb$, $^{209} Bi$, $ ^{235}U$ and $^{238}U$ at laboratory energy of 43.0 MeV have also been analyzed using the traditional transition state model. In all these calculations, optical model transmission coefficients with spin-orbit interaction have been used. In the case of magic nuclei, $^{208}Pb$ and $^{209} Bi$ it is found that the deduced values of $K_{0}^{2}$ are very small as compared to their corresponding values for $^{235}U$ and $^{238}U$ nuclei. This interpreted as due to shell structure, since significant shell and pairing effects appear for the magic nuclei $^{208} Pb$ and $^{209} Bi$.

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Authors

  • A.N. Behkami

    Mahabad Azad University

  • Seth Putterman

    Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287, USA, Department of Physics, Arizona State University, Tempe, AZ 85287, USA, College of Optical Sciences, University of Arizona, Colorado State University, University of Virginia, Auburn University, Northern Kentucky University, Utah Valley State College, Brigham Young University, Arizona State University, University of Amsterdam, New Mexico State university, University of Minesota, Pulse Field Facility, NHMFL, LANL, NM, Institute of Physics ASCR , Czech Republic, University of Minesota-Twin City, New Mexico State University, Director, Advanced Photon Source, Argonne National Lab, Australian Synchotron Source, Advanced Photon Source, Argonne National Lab, University of Arizona, U.S. Naval Research Laboratory, Wellesley College, Observatoire de Paris, France, Freie Universitat Berlin, Florida State Univ., Univ. Sci. Tech. China, Iowa State University, Lawrence Livermore National Laboratory, Mahabad Azad University, Carnegie Mellon University, Tempe Preparatory Academy, University of California, Los Angeles

  • Seth Putterman

    Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287, USA, Department of Physics, Arizona State University, Tempe, AZ 85287, USA, College of Optical Sciences, University of Arizona, Colorado State University, University of Virginia, Auburn University, Northern Kentucky University, Utah Valley State College, Brigham Young University, Arizona State University, University of Amsterdam, New Mexico State university, University of Minesota, Pulse Field Facility, NHMFL, LANL, NM, Institute of Physics ASCR , Czech Republic, University of Minesota-Twin City, New Mexico State University, Director, Advanced Photon Source, Argonne National Lab, Australian Synchotron Source, Advanced Photon Source, Argonne National Lab, University of Arizona, U.S. Naval Research Laboratory, Wellesley College, Observatoire de Paris, France, Freie Universitat Berlin, Florida State Univ., Univ. Sci. Tech. China, Iowa State University, Lawrence Livermore National Laboratory, Mahabad Azad University, Carnegie Mellon University, Tempe Preparatory Academy, University of California, Los Angeles

  • Seth Putterman

    Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287, USA, Department of Physics, Arizona State University, Tempe, AZ 85287, USA, College of Optical Sciences, University of Arizona, Colorado State University, University of Virginia, Auburn University, Northern Kentucky University, Utah Valley State College, Brigham Young University, Arizona State University, University of Amsterdam, New Mexico State university, University of Minesota, Pulse Field Facility, NHMFL, LANL, NM, Institute of Physics ASCR , Czech Republic, University of Minesota-Twin City, New Mexico State University, Director, Advanced Photon Source, Argonne National Lab, Australian Synchotron Source, Advanced Photon Source, Argonne National Lab, University of Arizona, U.S. Naval Research Laboratory, Wellesley College, Observatoire de Paris, France, Freie Universitat Berlin, Florida State Univ., Univ. Sci. Tech. China, Iowa State University, Lawrence Livermore National Laboratory, Mahabad Azad University, Carnegie Mellon University, Tempe Preparatory Academy, University of California, Los Angeles