Low-energy enhancement of magnetic dipole radiation.
Magnetic dipole strength functions are deduced from averages of a large number of M1 transition strengths calculated within the shell model for the nuclides 90Zr, 94Mo, 95Mo, and 96Mo. An enhancement of M1 strength toward low transition energy is found for all nuclides considered. Large M1 strengths appear for transitions between close-lying states with configurations including proton as well as neutron high-j orbits that recouple their spins and add up their magnetic moments coherently. The M1 strength function deduced from the calculated M1 transition strengths is compatible with the low-energy enhancement found in (3He, 3He') and (d, p) experiments. The Letter presents an explanation of the experimental findings.
Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany.
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Schwengner
Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, USA.
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Frauendorf
Department of Physics, University of Oslo, 0316 Oslo, Norway.
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Larsen