Yields of short-lived fission products produced following<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow /><mml:mrow><mml:mn>235</mml:mn></mml:mrow></mml:msup></mml:mrow><mml:mi mathvariant="normal">U</mml:mi><mml:mrow><mml:msub><mml:mrow><mml:mo>(</mml:mo><mml:mi>n</mml:mi></mml:mrow><mml:mrow><mml:mi mathvariant="normal">th</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mo>,</mml:mo><mml:mi>f</mml:mi><mml:mo>)</mml:mo></mml:math>

Tipnis, Sameer; Campbell, J. M.; Couchell, G.P.; Li, S.; Nguyen, Hieu V.; Pullen, D.J.; Schier, W.A.; Seabury, E. H.; England, T.R.

doi:10.1103/physrevc.58.905

Cited by 12 publications

(10 citation statements)

References 12 publications

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“…The 92 Rb cumulative fission yield following the thermal fission of 235 U definitely merits a new measurement. While both the ENDF/B and JEFF values of 0.048 agree within 0.3%, it has been reported to be 0.074 (11) by Tipnis et al, [31], that is, 50% larger than the JEFF value, which would mean that at 5.5 MeV, 92 Rb would contribute about 30% of the total electron spectra.…”

Section: U Fast (D)mentioning

confidence: 81%

Nuclear structure insights into reactor antineutrino spectra

2015

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Section: U Fast (D)mentioning

confidence: 81%

Nuclear structure insights into reactor antineutrino spectra

2015

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“…A careful study of fission yields derived from observed γ-ray transitions is described by Tipnis, et al [6]. These authors used a helium-jet system to rapidly transfer fission products produced in 235 U(n th , f) reactions from a fission chamber to an HPGe detector.…”

Section: Comparison With Experimentsmentioning

confidence: 99%

“…A similarly detailed comparison between the calculated and experimental spectra of Norman, et al is clearly unwarranted here because of the complications noted above; nonetheless, we can conclude that the general agreement is reasonable. Also, this method, coupled with accurately modeled benchmark spectra, may be very useful in assessing the general quality of the databases involved and may complement the approach described in [6]. It may also be possible to improve the quality of the evaluated data files where, at present, very large uncertainties exist.…”

Section: Comparison With Experimentsmentioning

confidence: 99%

“…As noted earlier, there is often no need to incorporate a highly-detailed delayed γ-ray source model such as that described in Section 2.1 into a Monte Carlo code in order to assess the effects of different attenuating media and geometries on the transmitted spectra, particularly when the shielding materials involved have thicknesses of a few attenuation mean free paths or more. We have found that the delayed gamma source function can be well represented in these cases by a piecewise-continuous function of the form: (6) where the coefficients A i and time constants τ i are defined over a given range of photon energies. Figure 5 shows representative examples of parameterized fits of this sort over 500-keV intervals for the case of thermal neutrons incident on 239 Pu (the corresponding fitting parameters are given in Table 2).…”

Section: Parameterized (Continuous) Representationmentioning

confidence: 99%

“…Such benchmark experiments have recently been done at Lawrence Berkeley National Laboratory [10] and may add to information gained from other experimental methods (e.g. [6]) for determining fission-fragment yields.…”

Section: Summary and Commentsmentioning

confidence: 99%

See 2 more Smart Citations

Modeling the Production of Beta-Delayed Gamma Rays for the Detection of Special Nuclear Materials

Hall¹,

Pruet²,

Brown³

et al. 2005

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The objective of this LDRD project was to develop one or more models for the production of β-delayed γ rays following neutron-induced fission of a special nuclear material (SNM) and to define a standardized formatting scheme which will allow them to be incorporated into some of the modern, general-purpose Monte Carlo transport codes currently being used to simulate inspection techniques proposed for detecting fissionable material hidden in seagoing cargo containers. In this report, we will describe a Monte Carlo model for β-delayed γ-ray emission following the fission of SNM that can accommodate arbitrary time-dependent fission rates and photon collection histories. The model involves direct sampling of the independent fission yield distributions of the system, the branching ratios for decay of individual fission products and spectral distributions representing photon emission from each fission product and for each decay mode. While computationally intensive, it will be shown that this model can provide reasonably detailed estimates of the spectra that would be recorded by an arbitrary spectrometer and may prove quite useful in assessing the quality of evaluated data libraries and identifying gaps in the libraries. The accuracy of the model will be illustrated by comparing calculated and experimental spectra from the decay of short-lived fission products following the reactions 235 U(n th , f) and 239 Pu(n th , f). For general-purpose transport calculations, where a detailed consideration of the large number of individual γ-ray transitions in a spectrum may not be necessary, it will be shown that a simple parameterization of the γ-ray source function can be defined which provides high-quality average spectral distributions that should suffice for calculations describing photons being transported through thick attenuating media. Finally, a proposal for ENDF-compatible formats that describe each of the models and allow for their straightforward use in Monte Carlo codes will be presented.

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