Statistical-model description of γ decay from compound-nucleus resonances

Fanto, P.; Alhassid, Y.; Weidenmüller, H. A.

doi:10.1103/physrevc.101.014607

Title: Statistical-model description of γ decay from compound-nucleus resonances

Journal Article · 12 January 2020 · Physical Review C

DOI: https://doi.org/10.1103/physrevc.101.014607 · OSTI ID:1800742

^[1]; Alhassid, Y. ^[2]; Weidenmüller, H. A. ^[3]

Yale Univ., New Haven, CT (United States); OSTI
Yale Univ., New Haven, CT (United States)
Max-Planck-Institut für Kernphysik, Heidelberg (Germany)

The statistical model of compound-nucleus reactions predicts that the fluctuations of the partial γ-decay widths for a compound-nucleus resonance are governed by the Porter-Thomas distribution (PTD), and that consequently the distribution of total γ-decay widths is very narrow. However, a recent experiment reported large fluctuations of the total γ-decay widths in the ⁹⁵Mo (n, γ) 96 Mo$$^\ast$$ reaction, contrary to this expectation. Furthermore, in recent theoretical works it was argued that sufficiently strong channel couplings can cause deviations of the partial width distributions from PTD. Here, we investigate whether the combined influence of a large number of nonequivalent γ-decay channels, each of which couples weakly to the compound-nucleus resonances, can modify the statistics of the partial widths. We study this effect in neutron scattering off ⁹⁵Mo within a random-matrix model that includes coupling to the entrance neutron channel and to the large number of γ channels. Using realistic coupling parameters obtained from empirical models for the level density and the γ strength function, we find that the PTD describes well the distribution of partial widths for all decay channels, in agreement with the statistical-model expectation. Furthermore, we find that the width of the distribution of the total γ-decay widths is insensitive to wide variations in the parameters of the γ strength function, as well as to deviations of the partial-width distributions from the PTD. Finally, our results rule out an explanation of the recent experimental data within a statistical-model description of the compound nucleus.

View Accepted Manuscript (DOE)

Cite

Export

Save

Research Organization:: Krell Institute, Ames, IA (United States); Yale Univ., New Haven, CT (United States)

Sponsoring Organization:: National Science Foundation (NSF); USDOE National Nuclear Security Administration (NNSA)

Grant/Contract Number:: FG02-91ER40608; NA0003864; SC0019521

OSTI ID:: 1800742

Journal Information:: Physical Review C, Journal Name: Physical Review C Journal Issue: 1 Vol. 101; ISSN 2469-9985

Publisher:: American Physical Society (APS)Copyright Statement

Country of Publication:: United States

Language:: English

References (43)

Statistical properties of many-particle spectra Mon, K. K.; French, J. B. Annals of Physics, Vol. 95, Issue 1 https://doi.org/10.1016/0003-4916(75)90045-7	journal	November 1975
Validity of random matrix theories for many-particle systems French, J. B.; Wong, S. S. M. Physics Letters B, Vol. 33, Issue 7 https://doi.org/10.1016/0370-2693(70)90213-3	journal	December 1970
Two-body random hamiltonian and level density Bohigas, O.; Flores, J. Physics Letters B, Vol. 34, Issue 4 https://doi.org/10.1016/0370-2693(71)90598-3	journal	March 1971
Gaussian distributions of shell-model eigenvector components Brown, B. A.; Bertsch, G. Physics Letters B, Vol. 148, Issue 1-3 https://doi.org/10.1016/0370-2693(84)91598-3	journal	November 1984
Simulation of γ cascades in complex nuclei with emphasis on assessment of uncertainties of cascade-related quantities Bečvář, F. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 417, Issue 2-3 https://doi.org/10.1016/S0168-9002(98)00787-6	journal	November 1998
Embedded random matrix ensembles for complexity and chaos in finite interacting particle systems Kota, V. Physics Reports, Vol. 347, Issue 3 https://doi.org/10.1016/S0370-1573(00)00113-7	journal	June 2001
The nuclear shell model as a testing ground for many-body quantum chaos Zelevinsky, Vladimir; Brown, B. Alex; Frazier, Njema Physics Reports, Vol. 276, Issue 2-3 https://doi.org/10.1016/S0370-1573(96)00007-5	journal	November 1996
Distribution of shell model reduced transition probabilities in 22Na Adams, A. A.; Mitchell, G. E.; Ormand, W. E. Physics Letters B, Vol. 392, Issue 1-2 https://doi.org/10.1016/S0370-2693(96)01510-9	journal	January 1997
RIPL – Reference Input Parameter Library for Calculation of Nuclear Reactions and Nuclear Data Evaluations Capote, R.; Herman, M.; Obložinský, P. Nuclear Data Sheets, Vol. 110, Issue 12 https://doi.org/10.1016/j.nds.2009.10.004	journal	December 2009
Many-body quantum chaos: Recent developments and applications to nuclei Gómez, J. M. G.; Kar, K.; Kota, V. K. B. Physics Reports, Vol. 499, Issue 4-5 https://doi.org/10.1016/j.physrep.2010.11.003	journal	March 2011
Nuclear Level Densities Grimes, S. M. INTERNATIONAL CONFERENCE ON NUCLEAR DATA FOR SCIENCE AND TECHNOLOGY, AIP Conference Proceedings https://doi.org/10.1063/1.1945235	conference	January 2005
The statistical model and nuclear level densities Ericson, Torleif Advances in Physics, Vol. 9, Issue 36 https://doi.org/10.1080/00018736000101239	journal	October 1960
Review of the k -body embedded ensembles of Gaussian random matrices Benet, L.; Weidenm ller, H. A. Journal of Physics A: Mathematical and General, Vol. 36, Issue 12 https://doi.org/10.1088/0305-4470/36/12/340	journal	March 2003
Statistical Theory of Nuclear Collision Cross Sections Moldauer, P. A. Physical Review, Vol. 135, Issue 3B https://doi.org/10.1103/PhysRev.135.B642	journal	August 1964
Statistical aspects of nuclear coupling to continuum Drożdż, S.; Okołowicz, J.; Płoszajczak, M. Physical Review C, Vol. 62, Issue 2 https://doi.org/10.1103/PhysRevC.62.024313	journal	July 2000
Statistical fluctuations of electromagnetic transition intensities and electromagnetic moments in pf -shell nuclei Hamoudi, A.; Nazmitdinov, R. G.; Shahaliev, E. Physical Review C, Vol. 65, Issue 6 https://doi.org/10.1103/PhysRevC.65.064311	journal	June 2002
Two-step γ cascades following thermal neutron capture in Mo 95 Krtička, M.; Bečvář, F.; Tomandl, I. Physical Review C, Vol. 77, Issue 5 https://doi.org/10.1103/PhysRevC.77.054319	journal	May 2008
Test of the statistical model in Mo 96 with the BaF 2 γ calorimeter DANCE array Sheets, S. A.; Agvaanluvsan, U.; Becker, J. A. Physical Review C, Vol. 79, Issue 2 https://doi.org/10.1103/PhysRevC.79.024301	journal	February 2009
Porter-Thomas distribution in unstable many-body systems Volya, Alexander Physical Review C, Vol. 83, Issue 4 https://doi.org/10.1103/PhysRevC.83.044312	journal	April 2011
Reduced neutron widths in the nuclear data ensemble: Experiment and theory do not agree Koehler, P. E. Physical Review C, Vol. 84, Issue 3 https://doi.org/10.1103/PhysRevC.84.034312	journal	September 2011
Extreme nonstatistical effects in γ decay of 95 Mo neutron resonances Koehler, P. E.; Larsen, A. C.; Guttormsen, M. Physical Review C, Vol. 88, Issue 4 https://doi.org/10.1103/PhysRevC.88.041305	journal	October 2013
Neutron width statistics in a realistic resonance-reaction model Fanto, P.; Bertsch, G. F.; Alhassid, Y. Physical Review C, Vol. 98, Issue 1 https://doi.org/10.1103/PhysRevC.98.014604	journal	July 2018
Open system of interacting fermions: Statistical properties of cross sections and fluctuations Celardo, G. L.; Izrailev, F. M.; Zelevinsky, V. G. Physical Review E, Vol. 76, Issue 3 https://doi.org/10.1103/PhysRevE.76.031119	journal	September 2007
Anomalous Fluctuations of s -Wave Reduced Neutron Widths of Pt 192 , 194 Resonances Koehler, P. E.; Bečvář, F.; Krtička, M. Physical Review Letters, Vol. 105, Issue 7 https://doi.org/10.1103/PhysRevLett.105.072502	journal	August 2010
Distribution of Partial Neutron Widths for Nuclei Close to a Maximum of the Neutron Strength Function Weidenmüller, Hans A. Physical Review Letters, Vol. 105, Issue 23 https://doi.org/10.1103/PhysRevLett.105.232501	journal	December 2010
Distribution of Resonance Widths and Dynamics of Continuum Coupling Celardo, G. L.; Auerbach, N.; Izrailev, F. M. Physical Review Letters, Vol. 106, Issue 4 https://doi.org/10.1103/PhysRevLett.106.042501	journal	January 2011
Neutron Resonance Widths and the Porter-Thomas Distribution Volya, Alexander; Weidenmüller, Hans A.; Zelevinsky, Vladimir Physical Review Letters, Vol. 115, Issue 5 https://doi.org/10.1103/PhysRevLett.115.052501	journal	July 2015
Modification of the Porter-Thomas Distribution by Rank-One Interaction Bogomolny, E. Physical Review Letters, Vol. 118, Issue 2 https://doi.org/10.1103/PhysRevLett.118.022501	journal	January 2017
Test of the Brink-Axel Hypothesis for the Pygmy Dipole Resonance Martin, D.; von Neumann-Cosel, P.; Tamii, A. Physical Review Letters, Vol. 119, Issue 18 https://doi.org/10.1103/PhysRevLett.119.182503	journal	November 2017
Wave Function Structure in Two-Body Random Matrix Ensembles Kaplan, Lev; Papenbrock, Thomas Physical Review Letters, Vol. 84, Issue 20 https://doi.org/10.1103/PhysRevLett.84.4553	journal	May 2000
Random matrices and chaos in nuclear physics: Nuclear reactions Mitchell, G. E.; Richter, A.; Weidenmüller, H. A. Reviews of Modern Physics, Vol. 82, Issue 4 https://doi.org/10.1103/RevModPhys.82.2845	journal	October 2010
Nuclear level densities Haq, R. U.; Wong, S. S. M. Canadian Journal of Physics, Vol. 60, Issue 10 https://doi.org/10.1139/p82-202	journal	October 1982
Nuclear Level Densities Huizenga, J. R.; Moretto, L. G. Annual Review of Nuclear Science, Vol. 22, Issue 1 https://doi.org/10.1146/annurev.ns.22.120172.002235	journal	December 1972
Resonance width distribution in RMT: Weak-coupling regime beyond Porter-Thomas Fyodorov, Yan V.; Savin, Dmitry V. EPL (Europhysics Letters), Vol. 110, Issue 4 https://doi.org/10.1209/0295-5075/110/40006	journal	May 2015
Large Petermann factor in chaotic cavities with many scattering channels Frahm, K. M.; Schomerus, H.; Patra, M. Europhysics Letters (EPL), Vol. 49, Issue 1 https://doi.org/10.1209/epl/i2000-00118-y	journal	January 2000
Reduced neutron widths in the nuclear data ensemble: Experiment and theory do not agree Koehler, P. E. arXiv https://doi.org/10.48550/arxiv.1001.0517	text	January 2010
Random Matrices and Chaos in Nuclear Physics: Nuclear Reactions Mitchell, G. E.; Richter, A.; Weidenmueller, H. A. arXiv https://doi.org/10.48550/arxiv.1001.2422	text	January 2010
Distribution of Resonance Widths and Dynamics of Continuum Coupling Celardo, G. L.; Auerbach, N.; Izrailev, F. M. arXiv https://doi.org/10.48550/arxiv.1010.4342	text	January 2010
Porter-Thomas distribution in unstable many-body systems Volya, Alexander arXiv https://doi.org/10.48550/arxiv.1011.5407	text	January 2010
Neutron Resonance Widths and the Porter-Thomas Distribution Volya, Alexander; Weidenmüller, Hans A.; Zelevinsky, Vladimir arXiv https://doi.org/10.48550/arxiv.1504.06771	text	January 2015
Test of the Brink-Axel hypothesis for the pygmy dipole resonance Martin, D.; von Neumann-Cosel, P.; Tamii, A. arXiv https://doi.org/10.48550/arxiv.1611.01789	text	January 2016
Neutron width statistics in a realistic resonance-reaction model Fanto, P.; Bertsch, G. F.; Alhassid, Y. arXiv https://doi.org/10.48550/arxiv.1710.00792	text	January 2017
Review of the k-Body Embedded Ensembles of Gaussian Random Matrices Benet, L.; Weidenmueller, H. A. arXiv https://doi.org/10.48550/arxiv.cond-mat/0207656	text	January 2002

Similar Records

Distribution of Resonance Widths and Dynamics of Continuum Coupling

Journal Article · 2011 · Physical Review Letters · OSTI ID:21532264

Celardo, G L; Auerbach, N; Izrailev, F M; +1 more

Deviations from the Porter-Thomas Distribution due to Nonstatistical 𝛾 Decay below the ¹⁵⁰Nd Neutron Separation Threshold

Journal Article · 2025 · Physical Review Letters · OSTI ID:3001507

Papst, O.; Isaak, J.; Werner, V.; +17 more

Porter-Thomas distribution in unstable many-body systems

Journal Article · 2011 · Physical Review. C, Nuclear Physics · OSTI ID:21499563

Volya, Alexander

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
Physics

Title: Statistical-model description of γ decay from compound-nucleus resonances

Citation Formats

References (43)

Similar Records

Related Subjects