Investigations for the use of the fast digitizers with detectors for radiative capture measurements at GELINA

Mihăilescu, L. C.; Borella, A.; Massimi, C.; Schillebeeckx, P.

doi:10.1016/j.nima.2008.11.119

Cited by 13 publications

(9 citation statements)

References 17 publications

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“…Possible bias effects due to such corrections are very small as was demonstrated in refs. [30,43]. However, it limits the upper energy region of the data obtained at the 12 m station to ≤ 70 keV for measurements without the sulfur permanent filter.…”

Section: Methodsmentioning

confidence: 97%

Neutron capture cross section measurements for 238U in the resonance region at GELINA

et al. 2016

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Abstract. Measurements were performed at the time-of-flight facility GELINA to determine the 238 U(n, γ) cross section in the resonance region. Experiments were carried out at a 12.5 and 60 m measurement station. The total energy detection principle in combination with the pulse height weighting technique was applied using C 6D6 liquid scintillators as prompt γ-ray detectors. The energy dependence of the neutron flux was measured with ionisation chambers based on the 10 B(n, α) reaction. The data were normalised to the isolated and saturated 238 U resonance at 6.67 eV. Special procedures were applied to reduce bias effects due to the weighting function, normalization, dead time and background corrections, and corrections related to the sample properties. The total uncertainty due to the weighting function, normalization, neutron flux and sample characteristics is about 1.5%. Resonance parameters were derived from a simultaneous resonance shape analysis of the GELINA capture data and transmission data obtained previously at a 42 m and 150 m station of ORELA. The parameters of resonances below 500 eV are in good agreement with those resulting from an evaluation that was adopted in the main data libraries. Between 500 eV and 1200 eV a systematic difference in the neutron width is observed. Average capture cross section data were derived from the experimental capture yield in the energy region between 3.5 keV and 90 keV. The results are in good agreement with an evaluated cross section resulting from a least squares fit to experimental data available in the literature prior to this work. The average cross section data derived in this work were parameterised in terms of average resonance parameters and included in a least squares analysis together with other experimental data reported in the literature.

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Section: Methodsmentioning

confidence: 97%

Neutron capture cross section measurements for 238U in the resonance region at GELINA

et al. 2016

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“…In refs. [11,21] it was shown that uncertainties for such dead time corrections are very small and can be neglected.…”

Section: Methodsmentioning

confidence: 99%

Neutron capture cross section measurements for 197Au from 3.5 to 84 keV at GELINA

et al. 2014

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Abstract. Cross section measurements have been performed at the time-of-flight facility GELINA to determine the average capture cross section for 197 Au in the energy region between 3.5 keV and 84 keV. Prompt γ-rays, originating from neutron-induced capture events, were detected by two C 6D6 liquid scintillators. The sample was placed at about 13 m distance from the neutron source. The total energy detection principle in combination with the pulse height weighting technique was applied. The energy dependence of the neutron flux was measured with a double Frisch-gridded ionization chamber based on the 10 B(n, α) reaction. The data have been normalized to the well-isolated and saturated197 Au resonance at 4.9 eV. Special care was taken to reduce bias effects due to the weighting function, normalization, dead time and background corrections. The total uncertainty due to normalization, neutron flux and weighting function is 1.0%. An additional uncertainty of 0.5% results from the correction for self-shielding and multiple interaction events. Fluctuations due to resonance structures have been studied by complementary measurements at a 30 m flight path station. The results reported in this work deviate systematically by more than 5% from the cross section that is recommended as a reference for astrophysical applications. They are about 2% lower compared to an evaluation of the 197 Au(n, γ) cross section, which was based on a least squares fit of experimental data available in the literature prior to this work. The average capture cross section as a function of neutron energy has been parameterized in terms of average resonance parameters. Maxwellian average cross sections at different temperatures have been calculated.

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“…with calibration sources, given in [6] [7] [15] have shown that the dead-time correction obtained by this method is correct to a fraction of one percent. In a recent comparison [16] of fast digitizers with a small dead time and a conventional system using a fixed dead time a systematic discrepancy of 2 % was observed for a dead-time correction factor of 0.45 in the conventional system in the extreme case of a saturated resonance in a neutron capture experiment.…”

Section: Dead-time Correctionmentioning

confidence: 99%

Neutron total cross section measurements of gold and tantalum at the nELBE photoneutron source

et al. 2013

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Neutron total cross sections of 197 Au and nat Ta have been measured at the nELBE photoneutron source in the energy range from 0.1 -10 MeV with a statistical uncertainty of up to 2 % and a total systematic uncertainty of 1 %. This facility is optimized for the fast neutron energy range and combines an excellent time structure of the neutron pulses (electron bunch width 5 ps) with a short flight path of 7 m. Because of the low instantaneous neutron flux transmission measurements of neutron total cross sections are possible, that exhibit very different beam and background conditions than found at other neutron sources. IntroductionExperimental neutron total cross sections as a function of neutron energy are a fundamental data set for the evaluation of nuclear data libraries. With increasing neutron energy the compound nucleus resonances cannot be resolved anymore and will start to overlap. In the energy range of fast neutrons, which is especially important for innovative nuclear applications, like accelerator driven systems for the transmutation of nuclear waste, the neutron total cross section can be described by optical model calculations (e.g. Au(n,) is an activation standard in dosimetric applications [4]. Precise total cross section data with a targeted uncertainty < 5 % will have a direct impact on future evaluations of neutron induced reactions on Au. Also an overlapping measurement from 200 keV to 2.5 MeV is of interest to check consistency.Tantalum is a non-corrosive metal of importance as a structural material in many nuclear and high-temperature applications, e.g. it is also a component in Reduced Activation Ferritic / Martensitic steels [5]. The fast neutron cross section of tantalum has been evaluated recently [6]. In that work, a careful measurement of the neutron total cross section from several tens of keV to several MeV with an accuracy goal of  1 % has been recommended.

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Investigations for the use of the fast digitizers with detectors for radiative capture measurements at GELINA

Cited by 13 publications

References 17 publications

Neutron capture cross section measurements for 238U in the resonance region at GELINA

Neutron capture cross section measurements for 238U in the resonance region at GELINA

Neutron capture cross section measurements for 197Au from 3.5 to 84 keV at GELINA

Neutron total cross section measurements of gold and tantalum at the nELBE photoneutron source

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