Deviations from the Porter-Thomas distribution due to nonstatistical decay below the  150Nd neutron separation threshold

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Papst, O. and Isaak, J. and Werner, V. and Savran, D. and Pietralla, N. and Battaglia, G. and Beck, T. and Beuschlein, M. and Finch, S. W. and Friman-Gayer, U. and Ide, K. E. and Janssens, R. V. F. and Jones, M. D. and Kleemann, J. and Löher, B. and Scheck, M. and Spieker, M. and Tornow, W. and Zidarova, R. and Zilges, A. (2025) Deviations from the Porter-Thomas distribution due to nonstatistical decay below the  150Nd neutron separation threshold. Physical Review Letters, 135 (5). 052501. ISSN 1079-7114 (https://doi.org/10.1103/n6zw-zhz2)

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Abstract

We introduce a new method for the study of fluctuations of partial transition widths based on nuclear resonance fluorescence experiments with quasimonochromatic linearly polarized photon beams below particle separation thresholds. It is based on the average branching of decays of =1 states of an even-even nucleus to the 2+1 state in comparison to the ground state. Between 5 and 7 MeV, a constant average branching ratio for decays from 1− states of 0.490(16) is observed for the nuclide 150Nd. Assuming 2-distributed partial transition widths, this average branching ratio is related to a degree of freedom of =1.93⁢(12), rejecting the validity of the Porter-Thomas distribution, requiring =1. The observed deviation can be explained by nonstatistical effects in the -decay behavior with contributions in the range of 9.4(10)% up to 94(10)%.

ORCID iDs

Papst, O., Isaak, J., Werner, V., Savran, D., Pietralla, N., Battaglia, G. ORCID logoORCID: https://orcid.org/0000-0003-1974-8521, Beck, T., Beuschlein, M., Finch, S. W., Friman-Gayer, U., Ide, K. E., Janssens, R. V. F., Jones, M. D., Kleemann, J., Löher, B., Scheck, M., Spieker, M., Tornow, W., Zidarova, R. and Zilges, A.;
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