Background identification and suppression for the measurement of (n,γ) reactions with the DANCE array at LANSCE

Reifarth, R.; Bredeweg, T. A.; Alpizar‐Vicente, A. M.; Browne, J.C.; Esch, Ernst I; Greife, U.; Haight, R. C.; Hatarik, R.; Kronenberg, A. K.; O’Donnell, J. M.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.; Wouters, J.M.

doi:10.1016/j.nima.2004.05.096

Cited by 82 publications

(71 citation statements)

References 4 publications

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“…Our 147 Sm(n, γ) measurements [3] were made using the Detector for Advanced Neutron Capture Experiments (DANCE) [21] at LANSCE. One problem working with odd-A nuclides is that there are two possible s-wave spin states (J = 3 and 4 in the case of 147 Sm), and performing the best test of the PTD requires knowing all the resonance spins.…”

Section: Testing the Ptd Withmentioning

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: Testing the Ptd Withmentioning

confidence: 99%

Neutron resonance data exclude random matrix theory

Koehler

Bečvář

Krtička

et al. 2012

Fortschritte der Physik

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“…Use of two channels enables the handling of both the fast and slow components of the signals from the BaF 2 crystals separately with a resolution of 8 bits with a sampling rate of 500 mega samples per second. The yield ratio of the fast to slow components of the signal is used for discrimination against the α background from natural radioactivity of Ra in the BaF 2 crystals [13]. The digitized signals provide information on timing, particle type and absorbed energy for each physical event in the crystals.…”

Section: Experiments and Data Processing A Experimental Detailsmentioning

confidence: 99%

“…The measurement was undertaken with the DANCE system [12,13] installed at a beam of the Lujan Neutron Scattering Center at the Los Alamos Neutron Science Center (LANSCE) [14,15]. Results of our analysis of these spectra with the statistical model are presented in this paper.…”

Section: Introductionmentioning

confidence: 99%

Measurement of theMo97(n,γ)reaction with the DANCEγcalorimeter array

et al. 2015

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Spectra of γ rays following the 97 Mo(n, γ) reaction were measured as a function of incident neutron energy with the DANCE (Detector for Advanced Neutron Capture Experiments) array of 160 BaF2 scintillation detectors at the Los Alamos Neutron Science Center using an enriched 97 Mo target. These spectra were used for the assignment of spins of the 97 Mo resonances up to neutron energy En = 1.7 keV, as well as in the study of photon strength functions (PSFs) in 98 Mo. Analysis of the spectra with the nuclear statistical model showed that they can be well reproduced with the same PSF models which well described the γ decay following slow neutron capture in 95 Mo. On the other hand, the spectra are inconsistent with PSFs describing some other experimental data in 98 Mo.

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“…The measurement was performed using the highly segmented Detector for Advanced Neutron Capture Experiments (DANCE) detector array [1,2] installed at the pulsed neutron beam at the Los Alamos Neutron Science Center (LANSCE) at Los Alamos National Laboratory [3] which produces a white spectrum of neutrons with energies from subthermal up to several MeV with the repetition rate of 20 Hz. These neutrons are sent to flight path 14 at the Manuel Lujan Jr. Neutron Scattering Center.…”

Section: Dance Experimentsmentioning

confidence: 99%

“…The DANCE detector array [1,2] is installed at 20.2 m on this flight path and consists of 160 BaF 2 scintillation crystals surrounding a sample and covering a solid angle of 3.5π. A 6 LiH shell about 6-cm thick is placed between the sample and the BaF 2 crystals in order to reduce the background from capture of scattered neutrons on Ba isotopes in the crystals.…”

Section: Dance Experimentsmentioning

confidence: 99%

Photon strength functions in Gd isotopes studied from radiative capture of resonance neutrons

Kroll

Baramsai

Mitchell

et al. 2014

EPJ Web of Conferences

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Abstract. The experimental spectra of γ rays following radiative neutron capture on isolated resonances of stable 152,154−158 Gd targets were measured by the DANCE calorimeter installed at the Los Alamos Neutron Scattering Center in New Mexico, USA. These spectra were analyzed within the extreme statistical model to get new information on the photon strength functions. Special emphasis was put on study of the scissors vibrational mode present in these isotopes. Our data show that the scissors-mode resonances are built not only on the ground states but also on the excited levels of all studied Gd isotopes. The scissors mode strength observed in 157,159 Gd products is significantly higher than in neighboring even-even nuclei 156,158 Gd. Such a difference indicates the existence of an odd-even effect in the scissors mode strength. Moreover, there exists no universal parameter-free model of the electric dipole photon strength function describing the experimental data in all of the Gd isotopes studied. The results for the scissors mode are compared with the (γ, γ ) data for the ground-state transitions and with the results from 3 He-induced reactions.

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Background identification and suppression for the measurement of (n,γ) reactions with the DANCE array at LANSCE

Cited by 82 publications

References 4 publications

Neutron resonance data exclude random matrix theory

Neutron resonance data exclude random matrix theory

Measurement of theMo97(n,γ)reaction with the DANCEγcalorimeter array

Photon strength functions in Gd isotopes studied from radiative capture of resonance neutrons

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