Experimental Determination of Photofission Neutron Multiplicities for 235U, 236U, 238U, and 232Th Using Monoenergetic Photons

Caldwell, J.T.; Dowdy, E.J.; Alvarez, Rodrigo; Berman, B. L.; Meyer, P.

doi:10.13182/nse80-a18695

Cited by 52 publications

(21 citation statements)

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“…The mean prompt photofission neutron multiplicities, ν, for 232 Th and 238 U are shown in Fig. 12, along with previous measurements [39,40], the ENDF/B-VII.1 evaluation [41], and an empirical model developed by Lengyel et al [42]. The error bars in the present data represent the range of values that increase the χ 2 of the fit by less than 1.…”

Section: B Prompt Photofission Neutron Multiplicitiessupporting

confidence: 61%

Near-barrier photofission in Th232 and U238

Silano

Karwowski

2018

Phys. Rev. C

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A study of photofission of 232 Th and 238 U was performed using quasi-monoenergetic, linearlypolarized γ-ray beams from the High Intensity γ-ray Source at Triangle Universities Nuclear Laboratory. The prompt photofission neutron polarization asymmetries, neutron multiplicities and the photofission cross sections were measured in the near-barrier energy range of 4.3-6.0 MeV. This data set constitutes the lowest energy measurements of those observables to date using quasimonoenergetic photons. Large polarization asymmetries are observed in both nuclei, consistent with the E1 excitation as observed by another measurement of this kind made in a higher energy range. Previous experimental evidence of a deep third minimum in the 238 U fission barrier has been identified as an accelerator-induced background.

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Section: B Prompt Photofission Neutron Multiplicitiessupporting

confidence: 61%

Near-barrier photofission in Th232 and U238

Silano

Karwowski

2018

Phys. Rev. C

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“…49 Mo(n,2n) 99 Mo reaction available in the literature , and the TENDL-2017 evaluation. Ikeda et al [177] contains three versions of the data measured on the basis of different beam-monitor reactions, and these are labelled 238 U(c,f) 99 Mo While there are no directly measured experimental data for the 238 U(c,f) 99 Mo reaction, thirteen experimental datasets were found in the literature for the total photofission cross section [183][184][185][186][187][188][189][190][191][192][193][194][195], as shown in Fig. 50.…”

Section: Momentioning

confidence: 99%

“…Data points from both Ref. [191] above 10 MeV and Ref. [192] below 14 MeV were also omitted for the same reason.…”

Section: Momentioning

confidence: 99%

“…51 (L = 17, Fig. 50 Experimental datasets for the 238 U(c,f) reaction available in the literature [183][184][185][186][187][188][189][190][191][192][193][194][195], and the Varlamov-Peskov (2007) evaluation [196] Data for the neutron-induced reaction on 238 U are most frequently used to estimate the cumulative photofission yield of 99 Mo. Such data are available in all of the national and international data libraries, but their accuracy is not high.…”

Section: Momentioning

confidence: 99%

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Recommended nuclear data for medical radioisotope production: diagnostic gamma emitters

Tárkányi

Ignatyuk

Hermanne

et al. 2018

J Radioanal Nucl Chem

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An extensive series of evaluations have been performed as part of an IAEA coordinated research project to study a set of nuclear reactions that produce the diagnostic gamma-ray emitting radionuclides 51 Cr, 99m Tc, 111 In, 123 I and 201 Tl. Recommended cross-section data in the form of excitation functions have been derived, along with quantifications of their uncertainties. These evaluations involved the compilation of all previously published values and newly measured experimental data, followed by critical assessments and selection of those experimental datasets and accompanying uncertainties judged to be fully valid and statistically consistent for model-independent least-squares fitting by means of Padé approximations. Integral yields as a function of the energy were also calculated on the basis of the recommended cross sections deduced from these various fits. All evaluated numerical results and their corresponding uncertainties are available online at www-nds.iaea.org/medical/gamma_emitters.html and also on the medical portal of the International Atomic Energy Agency/Nuclear Data Section (IAEA-NDS) www-nds.iaea.org/medportal/.

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“…The measured 235 U and 238 U count rates, weighted by the photofission cross-sections (σ f ) and average prompt neutron multiplicities (ν) for each isotope, were proportional to the amount of 235 U and 238 U in the beam. Previous measurements have found the ratio of σ f ν for 235 U to that of 238 U to be 1.027 0.09 at a beam energy of 6.1 MeV [32,33]. The uncertainty in this value was treated as a systematic uncertainty.…”

Section: Description Of the Experimentsmentioning

confidence: 99%

Tests of a novel method to assay SNM using polarized photofission and its sensitivity in the presence of shielding

Mueller

Ahmed

Kafkarkou

et al. 2015

Nuclear Instruments and Methods in Physics Research Section A:

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a b s t r a c t A novel method to identify Special Nuclear Material was recently developed (Mueller et al., 2014) [1].This method relies upon using a linearly polarized γ-ray beam to induce photofission of a sample and then comparing the prompt fission neutron yields in and out of the plane of beam polarization. The present paper will describe experimental tests of this new technique and assess its sensitivity in the presence of shielding. The capability of this technique to measure the enrichment of uranium was tested by using combinations of thin 235 U and 238 U foils of known enrichments. The sensitivity of this assay to shielding by lead, steel, and polyethylene was experimentally measured and simulated using GEANT4. These tests show that the measured asymmetry can indeed be used to determine the enrichment of materials composed of an admixture of 235 U and 238 U, and this asymmetry is relatively insensitive to moderate amounts of shielding.

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Experimental Determination of Photofission Neutron Multiplicities for ²³⁵U, ²³⁶U, ²³⁸U, and ²³²Th Using Monoenergetic Photons

Cited by 52 publications

References 0 publications

Near-barrier photofission in Th232 and U238

Near-barrier photofission in Th232 and U238

Recommended nuclear data for medical radioisotope production: diagnostic gamma emitters

Tests of a novel method to assay SNM using polarized photofission and its sensitivity in the presence of shielding

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