| 1. |
- Billnert, Robert, 1981, et al.
(författare)
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New prompt spectral gamma-ray data from the reaction Cf-252(sf) and its implication on present evaluated nuclear data files
- 2013
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Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 87:2
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Tidskriftsartikel (refereegranskat)abstract
- We present results from new spectral prompt gamma-ray measurements from the spontaneous fission of Cf-252. Apart from one recent experiment, about four decades have passed since the last dedicated experiments were reported in the literature. Hence, there was a need for a revision. We have measured prompt fission. rays with both cerium-doped LaBr3 and CeBr3 scintillation detectors, both of which exhibit excellent timing and good energy resolution. The emission yield was determined to be nu(gamma) = (8.30 +/- 0.08)/fission and nu(gamma) = (8.31 +/- 0.10)/fission, with the average energy of is an element of(gamma) = (0.80 +/- 0.01) MeV and is an element of(gamma) = (0.80 +/- 0.01) MeV and total energy of E-gamma,E-tot = (6.64 +/- 0.08) MeV and E-gamma,E-tot = (6.65 +/- 0.12) MeV, with the LaBr3 and CeBr3 detectors, respectively. Since the results from the two detectors are in excellent agreement and confirm the historical data, but not those in the present evaluated nuclear data files, we strongly recommend an update.
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| 2. |
- Billnert, Robert, 1981, et al.
(författare)
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Novel Scintillation Detectors for Prompt Fission γ-Ray Measurements
- 2012
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Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3884 .- 1875-3892. ; 31, s. 29-34
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Konferensbidrag (refereegranskat)abstract
- In this work we present first results from measurements of prompt fission γ-rays from the spontaneous fission in 252Cf. New and accurate data on corresponding γ-rays from the reactions 235U(nth,f) and 239Pu(nth,f) are highly demanded for the modeling of new Generation-IV nuclear reactor systems. For these experiments we employed scintillation detectors made out of new materials (LaBr3, LaCl3 and CeBr3), whose properties were necessary to know in order to obtain reliable results. Hence, we have characterized these detectors. In all the important properties these detectors outshine sodium-iodine detectors that where used in the 1970s, when the existing data had been acquired. Our finding is that the new generation of scintillation detectors is indeed promising, as far as an improved precision of the demanded data is concerned.
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| 3. |
- Billnert, R., et al.
(författare)
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Prompt γ-ray spectral data from 252Cf(SF), 235U(nth, f) and 241Pu(nth,f)
- 2014
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Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3884 .- 1875-3892. ; 59:C, s. 17-23
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Konferensbidrag (refereegranskat)abstract
- In this paper we talk about our work in developing a method to measure and analyze prompt fission γ-rays, as well as our results from the measurement of three different reactions, namely 252Cf(SF), 235U(nth,f) and 241Pu(nth,f). The first two had, at the beginning of our measurements, not been examined since the early 1970s, and the last reaction had never been measured. Our results show a slight improvement over evaluated data-tables in comparison with benchmark experiments, but can still not explain all of the underestimation witnessed. Our results also show that new evaluations is needed, especially for 252Cf(SF) and 241Pu(nth,f).
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| 4. |
- Dragić, A.L., et al.
(författare)
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Shape-isomer studies with resonance neutron capture
- 2014
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Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3884 .- 1875-3892. ; 59:C, s. 125-131
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Konferensbidrag (refereegranskat)abstract
- An experiment searching for formation of super-deformed shape isomers in odd uranium isotopes following neutron capture is designed at the GELINA neutron source of IRMM. We focus on neutron energies around the so-called intermediate structure in the fission cross-section, where the coupling between compound states above the first and the second minimum is largest. The experimental arrangement is described. The results of a feasibility study on the population of the shape isomer in 235U, using a 234U target, together with the results from first run with a 238U target are presented.
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| 5. |
- Eckardt, C., et al.
(författare)
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Development of an Active 238UF6 Gas Target
- 2012
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Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3884 .- 1875-3892. ; 31, s. 141-146
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Konferensbidrag (refereegranskat)abstract
- At the superconducting 130 MeV Darmstadt electron linac S-DALINAC a new source of spin-polarized electrons using a GaAs cathode has been installed, opening the path for experiments with polarized electron and photon beams for nuclear structure studies at low momentum transfers, e.g., the search for forward-backward asymmetries originating from parity non-conservation (PNC) in the photon-induced fission process of 238U.Detailed studies of different properties, e.g., the energy dependence of fission modes, the population of fission isomers, or the search for (PNC) effects in the photon-induced fission process of 238U, depends on high quality data, therefore needing high luminosities. An active gas target containing uranium may overcome the problem that large solid target thicknesses cause poor energy and angular resolution.A single Frisch-grid ionization chamber has been built to test a mixture of standard counting gases (e.g., argon) with depleted uraniumhexafiliguoride (238UF6) using a triple alpha source, evaluating signal quality and drift velocity. For mass fractions up to 2 percent of 238U in the counting gas. The drift velocity increases with rising UF6 content, while a good signal quality and energy resolution is preserved.
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| 6. |
- Enders, J., et al.
(författare)
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Reactions with polarized electrons and photons at low momentum transfers at the superconducting Darmstadt electron linear accelerator S-DALINAC
- 2011
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Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 295:1, s. Art. no. 012152-
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Konferensbidrag (refereegranskat)abstract
- A source of polarized electrons has been installed at the superconducting Darmstadt electron linear accelerator S-DALINAC. Experiments with polarized electrons from 100 keV to about 80 MeV are expected to commence in early 2011. This contribution summarizes the status of the polarized source as well as ongoing preparations for the experimental program with polarized beams. In particular, we present results on unpolarized test experiments of the, 234,238U(γ,f) reactions and considerations for the 2D(e→,e′p) and reactions.
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| 7. |
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| 8. |
- Jurado, B., et al.
(författare)
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Investigation of the surrogate-reaction method via the simultaneous measurement of gamma-emission and fission probabilities
- 2017
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Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. ; 146
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Konferensbidrag (refereegranskat)abstract
- We present the results of two experiments where we have measured for the first time simultaneously the fission and gamma-decay probabilities induced by different surrogate reactions. In particular, we have investigated the 238 U(d,p), 238 U( 3 He,t) and 238 U( 3 He, 4 He) reactions as surrogates for the neutron-induced n + 238 U, n + 237 Np and n + 236 U reactions, respectively. In the region where gamma emission, neutron emission and fission compete, our results for the fission probabilities agree fairly well with the neutron-induced data, whereas our gamma-decay probabilities are significantly higher than the neutron-induced data. The interpretation of these results is not obvious and is discussed within the framework of the statistical model with preliminary results for calculated spin-parity distributions populated in surrogate reactions. We also present future plans for surrogate-reaction studies in inverse kinematics with radioactive-ion beams at storage rings.
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| 9. |
- Lebois, M., et al.
(författare)
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Studies for γ-ray emission in the fission process with LICORNE
- 2016
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Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. ; 122:01010
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Konferensbidrag (refereegranskat)abstract
- The LICORNE neutron source is a new device at the ALTO facility. Its use of inverse kinematics makes the production of naturally focused neutron beams possible with an energy range of 0.5 to 4 MeV. This is perfect for any studies concerning fast neutron induced reaction based on detection setup that require to be placed in a compact geometry - such as Ge based ? detection setup. In this paper, neutron production with LICORNE is described. The development of a gascell target and the extension of the energy range up to 7 MeV with the p(11B,n)11C are presented. An overview of the major research fields studied with LICORNE is given and two types of experiment are presented. The first one dedicated to prompt fission ?-ray emission in fission, as a function of incident neutron energy, is described. Some preliminary results are shown. The second, in the context of the MINORCA campaign, is detailed. The most recent outcomes in the data analysis process are also presented.
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| 10. |
- Lutter, G., et al.
(författare)
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Radiopurity of a CeBr3 crystal used as scintillation detector
- 2013
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Ingår i: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002. ; 703, s. 158-162
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Tidskriftsartikel (refereegranskat)abstract
- Cerium bromide (CeBr3) has recently been shown to exhibit several properties making it a suitable material as a scintillation detector in nuclear physics applications. The intrinsic activity of gamma-ray emitting radionuclides in a 38.1 mm x 38.1 mm (diameter x height) crystal of CeBr3 was investigated. The measurements were carried out in the HADES underground laboratory located 225 m underground. Two primordial radionuclides were detected; Ac-227 (and its daughters) with massic activity of 0.30 +/- 0.02 Bq/kg and La-138 with massic activity of 7.4 +/- 1.0 mBq/kg. Two activation products were also detected; Ce-139 and Br-82. Their massic activities (assuming a homogeneous distribution in the crystal) just before taking the CeBr3 crystal underground were 4.3 +/- 0.3 mBq/kg and 18 +/- 4 mBq/kg correspondingly. None of the other common primordial radionuclides (K-49, Ra-226, Ra-228, Th-228, and U-235) were detected and their detection limits were below 2 mBq/kg except for U-238 for which the upper limit was 135 mBq/kg and Pb-210 with an upper limit of 600 mBq/kg.
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