Fourier Transform: A Tool to Measure Statistical Level Properties in Very Complex Spectra

Leviandier, Luc; Lombardi, M.; Jost, R.; Pique, J. P.

doi:10.1103/physrevlett.56.2449

Cited by 201 publications

(151 citation statements)

References 23 publications

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“…[9,10] appear to have ignored these limitations, and the good agreement between data and theory claimed appears to be due to the fact that many of the data used were selected using the theory being tested. Other tests that are purported to be less sensitive to missing or spurious resonances have been proposed [40], but have been shown [41] to lead to ambiguous results for sample sizes typical of nuclear data.…”

Section: Discussionmentioning

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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Section: Discussionmentioning

confidence: 99%

Neutron resonance data exclude random matrix theory

Koehler

Bečvář

Krtička

et al. 2012

Fortschritte der Physik

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“…Yet there is more to this if we consider the square of the Fourier transforms |C(t)| 2 of the spectra. This is so because the Fourier transform in the GSE case does not only have the characteristic "correlation hole" [8] at small frequencies, which is due to the long range stiffness of the spectrum, but in addition a very marked feature namely a singularity at frequency 1 [2]. This singularity corresponds to oscillations that in principle can be seen in the two-level cluster function Y 2 (E) or the number variance Σ 2 (L), but are most spectacular in the Fourier transform or the two-body form factor b(t) related to the Fourier transform by |b(t) − 1| 2 = |C(t)| 2 .…”

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confidence: 99%

“…For the GOE, amplitudes are independently distributed according to a Gaussian. This leads to a Porter-Thomas distribution for the intensities [2] and to the multiplication of b(t) by a factor of 1/3 in the formula relating b(t) to |C(t)| 2 [6,8]. We can study the Fourier transform of the intensity spectra of the nuclear data ensemble for those cases where partial width are available (approx.…”

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New evidence of GOE statistics for compound nuclear resonances

1994

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“…It would also be helpful to find alternate signatures of chaos which do not place such stringent requirements on the quality of data. We are currently beginning to explore the use of the Fourier transform as a tool for identifying chaos in nuclear spectra; this technique has been used in molecular physics to analyze anticrossing spectra [Lev86]. We hope to apply the technique to the analysis of the nearly 700 levels found recently in p+48Ti [Li91].…”

Section: Energy Levels Of 30p For Fluctuation Studiesmentioning

confidence: 99%

The Triangle Universities Nuclear Laboratory

Tornow¹

2001

Nuclear Physics News

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DISCLAIMERThis report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Referenee herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herei_a do not necessarily state or reflect those of the United States Government or any agency thereof. TRIANGLE UNIVERSITIES NUCLEAR LABORATORY INTRODUCTIONTriangle Universities Nuclear Laboratory (TUNL) has had a very successful year in 1990-91, with much progress being made in research, instrumentation development, and the training of nuclear physics students from the three collaborating universitiesDuke, North Carolina State, and University of North Carolina.In research, the TRIPLE collaboration at LAMPF is finding interesting and unexpected systematics in the parity-violating amplitudes for epithermal-neutron scattering. The collaboration is beginning experiments to significantly decrease the limits on time-reversalinvariance violation in the strong interaction. The expertise of TUNL in the construction and characterization of cryogenic polarized targets of elements from hydrogen to holmium continues to be important in forefront nuclear physics research.We have a broad-ranging program for probing the low-to medium-energy internucleon interactions, starting with n-p scattering and progressing to the three-and several-nucleon systems. Of particular interest are three-nucleon systems, both in elastic scattering and in three-body breakup. In the past year we have made rigorous calculations of these systems, using modem nuclear forces and the Cray Y-MP at North Carolina Supercomputer Center. Several experiments to test the predictions are underway at TUNL. Many of these require the intense beams of polarized deuterons provided by our new high-intensity atomic-beam source. Among the questions of fundamental interest are the nature of three-nucleon forces and the extent of charge-independence or charge-symmetry breaking in the two-nucleon interaction.Other studies of the dynamics of very light nuclei that engaged our efforts include spin observables at very low energies (using our new low energy beam facility and the intense polarized-ion source), and D-state parameters for light nuclei studied by transfer and radiative-capture reactions.Several facets of the nuclear many-body problem and nuclear structure have been elucidated through our research programs during 1990-91. Our program in nuclear astrophysics, w,hich uses a wide variety of techn...

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Fourier Transform: A Tool to Measure Statistical Level Properties in Very Complex Spectra

Cited by 201 publications

References 23 publications

Neutron resonance data exclude random matrix theory

Neutron resonance data exclude random matrix theory

New evidence of GOE statistics for compound nuclear resonances

The Triangle Universities Nuclear Laboratory

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