Multiplicity Spectrometer for Measuring Neutron Cross Sections

Muradyan, G.V.; Adamchuk, Yu.V.; Shchepkin, Yu.G.; Voskanyan, M. A.

doi:10.13182/nse85-a17431

Cited by 40 publications

(18 citation statements)

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“…The average multiplicity is expected to be different for J − than for J + . This conjecture was established [1,2,3] by Monte Carlo simulations of the gamma-cascades following neutron capture. The J-spin effect on multiplicity, although not large for Mo, (∆M J / < M >∼ 7%), results in the separation of M J values of s-wave resonances into two different groups, corresponding to the two possible spin values J + = 3 and J − = 2.…”

Section: Methodsmentioning

confidence: 94%

Neutron capture reactions on Mo and Gd isotopes using the DANCE array

Mitchell¹

2008

Proceedings of Workshop on Photon Strength Functions and Related Topics — PoS(PSF07)

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The γ rays following the 94,95 Mo(n, γ)Mo reactions have been studied by the time-of-flight method with the DANCE (Detector for Advanced Neutron Capture Experiments) array of 160 BaF 2 scintillation detectors at the Los Alamos Neutron Science Center. The targets were enriched samples. The γ-ray multiplicities and energy spectra for different multiplicities were measured in s-and p-wave resonances up to E n = 10 keV for 94 Mo and up to E n = 2 keV for 95 Mo. Preliminary analysis assigned definite spins and parities in 96 Mo for about 60% of the resonances, while tentative spins and parities were assigned for the rest of observed resonances. In 95 Mo the parities were determined for the observed resonances, confirming previously known assignments. Workshop on Photon Strength Functions and Related Topics

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Section: Methodsmentioning

confidence: 94%

Neutron capture reactions on Mo and Gd isotopes using the DANCE array

Mitchell¹

2008

Proceedings of Workshop on Photon Strength Functions and Related Topics — PoS(PSF07)

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“…The technique was first proposed in the 60's by Coceva, et al [12] and later refined into multiplicity spectrometry by Muradyan et al [13]. To date the multiplicity technique has been applied to DANCE data for 94,95 Mo(n,γ) [14] and 147 Sm(n,γ) [15].…”

Section: Statistical Properties Of Nucleimentioning

confidence: 99%

Neutron capture reactions at DANCE

Demetriou¹,

Julin²,

Harissopulos³

2008

AIP Conference Proceedings

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The Detector for Advanced Neutron Capture Experiments (DANCE) is a 4π BaF 2 array consisting of 160 active detector elements. The primary purpose of the array is to perform neutron capture cross section measurements on small ( 100 µg) and/or radioactive ( 100 mCi) species. The measurements made possible with this array will be useful in answering outstanding questions in the areas of national security, threat reduction, nuclear astrophysics, advanced reactor design and accelerator transmutation of waste. Since the commissioning of DANCE we have performed neutron capture cross section measurements on a wide array of medium to heavy mass nuclides. Measurements to date include neutron capture cross sections on 241,243 Am, neutron capture and neutron-induced fission cross sections and capture-to-fission ratio (α = σ γ /σ f ) for 235 U using a new fission-tagging detector as well as neutron capture cross sections for several astrophysics branchpoint nuclei. Results from several of these measurements will be presented along with a discussion of additional physics information that can be extracted from the DANCE data.

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“…Measurement Procedure. The capture cross section was obtained, as in [1], by means of a universal method based on measuring the distribution of the number of particles emitted by an excited nucleus and simultaneously determining the energy of each particle [3]. The essence of the method is to identify, by measuring the distribution of the number of γ-rays emitted as a result of an interaction, events with different types of neutron-nuclei interactions.…”

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confidence: 99%

Measurement of neutron capture and fission cross sections of 236U

2011

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The cross sections for radiative capture and fission for 236 U in the neutron energy ranges 1-2000 eV and 1-1000 eV, respectively, have been measured. The measurements were performed on a flight baseline 5.2 m of the FAKEL linear electron accelerator at the National Research Center Kurchatov Institute using a method based on measuring the distribution of the number of particles emitted by an excited nucleus with simultaneous measurement of the energy of each particle. The spectrum of the neutrons incident on a sample was measured by detecting the reaction 10 B(n, α) 7 Li. The cross sections were normalized with respect to the resonance in 236 U at 5.45 eV. The data obtained are compared with the results of other experiments and evaluated data.The neutron radiative capture cross section for 236 U is of considerable interest for calculating nuclear reactors, since it accumulates in the fuel and absorbs a large fraction of the neutrons with very little subsequent fission. In addition, it is necessary to know this cross section to develop a technology for reprocessing radioactive wastes.Most experimental data on the radiative capture cross section were obtained for neutron energies greater than several kilo-electron-volts. Below E n~ 2 keV the capture cross section has been measured directly in two experiments [1, 2], whose results are clearly at variance. In [2], the cross section was determined only above 300 eV. In the region where the energy ranges overlap, the data of [1] are approximately 20% higher than in [2]. At the same time, the required error in this quantity is 5% in the indicated region.The procedure examined in the present article makes it possible to obtain, in addition to the capture cross section, information about the fission cross section, which can serves as a basis for developing a new independent method of measuring small fission cross sections. Measurement Procedure. The capture cross section was obtained, as in [1], by means of a universal method based on measuring the distribution of the number of particles emitted by an excited nucleus and simultaneously determining the energy of each particle [3]. The essence of the method is to identify, by measuring the distribution of the number of γ-rays emitted as a result of an interaction, events with different types of neutron-nuclei interactions. The distribution is the dependence of the number of events on the number of emitted γ-rays. Radiative capture, fission, and scattering events are concentrated in different regions of this distribution, and this is what makes their separation possible. The indicated distribution is measured using a multi-section scintillation 4π-detector with almost 100% efficiency by recording multiple coincidences of counts from its sections. The experimental sample is placed at the center of a through channel of the detector, through which the neutron beam passes. To protect the scintillator from the neutrons scattered by the sample, the channel is surrounded by a layer of 10 B, which serves simultaneously as a (n, γ) c...

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Multiplicity Spectrometer for Measuring Neutron Cross Sections

Cited by 40 publications

References 1 publication

Neutron capture reactions on Mo and Gd isotopes using the DANCE array

Neutron capture reactions on Mo and Gd isotopes using the DANCE array

Neutron capture reactions at DANCE

Measurement of neutron capture and fission cross sections of 236U

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