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Studies of simple excited neutron s-wave resonances in the medium-light target nuclides 28Si, 32S, 40Ca, 52Cr and 96Zr have given results which contradict the independent particle model. An important result is the Gaussian-like distribution of the nearest level spacings for doorway states, which show no spacing smaller than half the average level spacing. A level repulsion effect indicated in doorway structures and the fragmentation of doorway states into 3p-2h states near the 3p-2h threshold are observed. The respective parameters are not statistically distributed, but increase monotonically with neutron energy. The doorway resonance spectrum with the Gaussian-like distribution for the spacings has similar properties to a lattice vibrational spectrum with almost equally spaced levels. The energy of the phonons can be determined by the spacing of the resonances, and the lifetime of the phonons by the fluctuation of the spacings. The rather good agreement of this lifetime with that of resonances calculated from the average neutron width can be considered as a validity test for the lattice-like model of a nucleus.

Additional information

Authors: ROHR G, JRC Geel (BE)
Bibliographic Reference: Paper presented: XX-th International Symposium on Nuclear Physics - Nuclear Reaction Mechanisms, Gaussig (DE), Nov. 12-15, 1990
Availability: Available from (1) as Paper EN 35846 ORA
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