Evidence for Violation of the Porter-Thomas Postulate in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">Th</mml:mi></mml:mrow><mml:mprescripts /><mml:mrow /><mml:mrow><mml:mn>232</mml:mn></mml:mrow><mml:mrow /><mml:mrow /></mml:mmultiscripts></mml:mrow></mml:math>

Forman, L.; Schelberg, A.D.; Warren, J.H.; Glass, Neel W.

doi:10.1103/physrevlett.27.117

Cited by 22 publications

(14 citation statements)

References 3 publications

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“…It is interesting that a (parity) doorway model has been proposed to explain the so-called sign effect [37] in parity-violating asymmetries for p-wave 232 Th+n resonances, which occurs at about the same energy as the reported [31,32,33,34] deviation from a PT distribution for the neutron widths in this nuclide. It was expected (based on arguments similar to those leading to the PT distribution) that the signs of these parity-violating asymmetries would be random.…”

Section: Discussionmentioning

confidence: 94%

“…Indeed we know of no physical explanation why TRIV would be manifested in these nuclides at this energy at such levels. It seems more likely that an unknown nuclear structure effect, perhaps one related to deformation, is responsible for the reported anomalies [2,31,32,33,34]. Finally, with current techniques it should be possible to significantly improve both the accuracy and sensitivity of the previous experiment on which the present 147 Sm neutron widths are based [20].…”

Section: Discussionmentioning

confidence: 99%

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Spin measurements forSm147+nresonances: Further evidence for nonstatistical effects

et al. 2007

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We have determined the spins J of resonances in the 147 Sm(n, γ) reaction by measuring multiplicities of γ-ray cascades following neutron capture. Using this technique, we were able to determine J values for all but 14 of the 140 known resonances below E n = 1 keV, including 41 firm J assignments for resonances whose spins previously were either unknown or tentative. These new spin assignments, together with previously determined resonance parameters, allowed us to eV from an analysis of 147 Sm(n,α) data, we divided the data into two regions; 0 < E n < 350 eV and 350 < E n < 700 eV. Using neutron widths from a previous measurement (corrected for new unresolved doublets identified in this work) and published techniques for correcting for missed resonances and for testing whether data are consistent with a Porter-Thomas distribution, we found that the Γ 0 n distribution for resonances below 350 eV is consistent with the expected PorterThomas distribution. On the other hand, we found that Γ 0 n data in the 350 < E n < 700 eV region are inconsistent with a Porter-Thomas distribution, but in good agreement with a χ 2 distribution having ν ≥ 2 We discuss possible explanations for these observed non-statistical effects and their possible relation to similar effects previously observed in other nuclides. * Electronic address: koehlerpe@ornl.gov 2

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Section: Discussionmentioning

confidence: 94%

Section: Discussionmentioning

confidence: 99%

Spin measurements forSm147+nresonances: Further evidence for nonstatistical effects

et al. 2007

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“…There also have been several other reported disagreements with the PTD [11][12][13][14][15], which we briefly describe in Section 6. To our knowledge, those results have never been explained or retracted.…”

Section: Introductionmentioning

confidence: 89%

“…There have been several reports [11][12][13][14] that the lowest energy neutron resonances in 232 Th deviate strongly from the PTD. Our ML analysis [33] of the data verifies these reports; the data change from disagreeing (ν n = 3.8 ± 1.3) to agreeing (ν n = 0.83 ± 0.68) with the PTD over the first two groups of 25 resonances.…”

Section: Other Reported Deviations From the Ptdmentioning

confidence: 99%

Neutron resonance data exclude random matrix theory

Koehler

Bečvář

Krtička

et al. 2012

Fortschritte der Physik

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Key words Porter-Thomas distribution, random matrix theory.Almost since the time it was formulated, the overwhelming consensus has been that random matrix theory (RMT) is in excellent agreement with neutron resonance data. However, over the past few years, we have obtained new neutron-width data at Oak Ridge and Los Alamos National Laboratories that are in stark disagreement with this theory. We also have reanalyzed neutron widths in the most famous data set, the nuclear data ensemble (NDE), and found that it is seriously flawed, and, when analyzed carefully, excludes RMT with high confidence. More recently, we carefully examined energy spacings for these same resonances in the NDE using the ∆3 statistic. We conclude that the data can be found to either confirm or refute the theory depending on which nuclides and whether known or suspected p-wave resonances are included in the analysis, in essence confirming results of our neutron-width analysis of the NDE. We also have examined radiation widths resulting from our Oak Ridge and Los Alamos measurements, and find that in some cases they do not agree with RMT. Although these disagreements presently are not understood, they could have broad impact on basic and applied nuclear physics, from nuclear astrophysics to nuclear criticality safety.

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“…32 Several of the measurements of the 232 Th capture cross-section below 1 MeV, renormalized as described, are compared in Fig. 1 21 and by 51 is mostly sensitive to the value of the effective scattering radius, and hence is not very helpful in evaluating average strength functions. The s-wave parameters given in parentheses in Table X were assumed by Uttley et aZ.…”

Section: Macklin Pasma and Gibbons (1963)mentioning

confidence: 99%

Evaluation of the /sup 232/Th neutron capture cross section above 3 keV

Saussure¹,

Macklin²

1977

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Evidence for Violation of the Porter-Thomas Postulate inTh232

Cited by 22 publications

References 3 publications

Spin measurements forSm147+nresonances: Further evidence for nonstatistical effects

Spin measurements forSm147+nresonances: Further evidence for nonstatistical effects

Neutron resonance data exclude random matrix theory

Evaluation of the /sup 232/Th neutron capture cross section above 3 keV

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