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1.
  • Gjestvang, D., et al. (författare)
  • Examination of how properties of a fissioning system impact isomeric yield ratios of the fragments
  • 2023
  • Ingår i: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 108:6
  • Tidskriftsartikel (refereegranskat)abstract
    • The population of isomeric states in the prompt decay of fission fragments-so-called isomeric yield ratios (IYRs)-is known to be sensitive to the angular momentum J that the fragment emerged with, and may therefore contain valuable information on the mechanism behind the fission process. In this work, we investigate how changes in the fissioning system impact the measured IYRs of fission fragments to learn more about what parameters affect angular momentum generation. To enable this, a new technique for measuring IYRs is first demonstrated. It is based on the time of arrival of discrete gamma rays, and has the advantage that it enables the study of the IYR as a function of properties of the partner nucleus. This technique is used to extract the IYR of 134Te, strongly populated in actinide fission, from the three different fissioning systems: 232Th(n, f), 238U(n, f), at two different neutron energies, as well as 252Cf(sf). The impacts of changing the fissioning system, the compound nuclear excitation energy, the minimum J of the binary partner, and the number of neutrons emitted on the IYR of 134Te are determined. The decay code TALYS is used in combination with the fission simulation code FREYA to calculate the primary fragment angular momentum from the IYR. We find that the IYR of 134Te has a slope of 0.004 +/- 0.002 with increase in compound nucleus (CN) mass. When investigating the impact on the IYR of increased CN excitation energy, we find no change with an energy increase similar to the difference between thermal and fast fission. By varying the mass of the partner fragment emerging with 134Te, it is revealed that the IYR of 134Te is independent of the total amount of prompt neutrons emitted from the fragment pair. This indicates that neutrons carry minimal angular momentum away from the fission fragments. Comparisons with the FREYA+TALYS simulations reveal that the average angular momentum in 134Te following 238U(n, f) is 6.0 h over bar . This is not consistent with the value deduced from recent CGMF calculations. Finally, the IYR sensitivity to the angular momentum of the primary fragment is discussed. These results are not only important to help understanding the underlying mechanism in nuclear fission, but can also be used to constrain and benchmark fission models, and are relevant to the gamma -ray heating problem of reactors.
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2.
  • Ledoux, X., et al. (författare)
  • The Neutrons for Science Facility at SPIRAL-2
  • 2014
  • Ingår i: Nuclear Data Sheets. - : Elsevier BV. - 0090-3752 .- 1095-9904. ; 119, s. 353-356
  • Tidskriftsartikel (refereegranskat)abstract
    • The Neutrons For Science (NFS) facility is a component of SPIRAL-2 laboratory under construction at Caen (France). SPIRAL-2 is dedicated to the production of high intensity Radioactive Ions Beams (RIB). It is based on a high-power linear accelerator (LINAG) to accelerate deuterons beams in order to produce neutrons by breakup reactions on a C converter. These neutrons will induce fission in U-238 for production of radioactive isotopes. Additionally to the RIB production, the proton and deuteron beams delivered by the accelerator will be used in the NFS facility. NFS is composed of a pulsed neutron beam and irradiation stations for cross-section measurements and material studies. The beams delivered by the LINAG will allow producing intense neutron beams in the 100 keV-40 MeV energy range with either a continuous or quasi-mono-energetic spectrum. At NFS available average fluxes will be up to 2 orders of magnitude higher than those of other existing time-of-flight facilities in the 1 MeV - 40 MeV range. NFS will be a very powerful tool for fundamental physics and application related research in support of the transmutation of nuclear waste, design of future fission and fusion reactors, nuclear medicine or test and development of new detectors. The facility and its characteristics are described, and several examples of the first potential experiments are presented.
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3.
  • Qi, L., et al. (författare)
  • Prompt fission gamma-ray emission spectral data for Pu-239(n,f) using fast directional neutrons from the LICORNE neutron source
  • 2018
  • Ingår i: SCIENTIFIC WORKSHOP ON NUCLEAR FISSION DYNAMICS AND THE EMISSION OF PROMPT NEUTRONS AND GAMMA RAYS (THEORY-4). - : EDP Sciences. - 9782759890316
  • Konferensbidrag (refereegranskat)abstract
    • Prompt fission gamma-ray spectra (PFGS) have been measured for the Pu-239(n,f) reaction using fast neutrons at E-n =1.81 MeV produced by the LICORNE directional neutron source. The setup makes use of LaBr3 scintillation detectors and PARIS phoswich detectors to measure the emitted prompt fission gamma rays (PFG). The mean multiplicity, average total energy release per fission and average energy of photons are extracted from the unfolded PFGS. These new measurements provide complementary information to other recent work on thermal neutron induced fission of Pu-239 and spontaneous fission of Cf-252.
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4.
  • Enders, J., et al. (författare)
  • Reactions with polarized electrons and photons at low momentum transfers at the superconducting Darmstadt electron linear accelerator S-DALINAC
  • 2011
  • Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 295:1, s. Art. no. 012152-
  • 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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5.
  • Gatera, A., et al. (författare)
  • Prompt-fission γ -ray spectral characteristics from Pu 239 (nth,f)
  • 2017
  • Ingår i: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 95:6
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper we present new results for prompt fission γ-ray spectral characteristics from the thermal neutron induced fission of Pu∗240. The measured spectra were unfolded by using the detectors' response functions, simulated with geant4. We obtained in average per fission a γ-ray multiplicity Mγ=(7.35±0.12), a mean photon energy ϵγ=(0.85±0.02) MeV, and an average total energy released in fission Ēγ,tot=(6.27±0.11) MeV. Our results are in good agreement with historical data measured in the 1970s by Verbinski et al. and results from recent calculations in the framework of Monte Carlo Hauser-Feshbach models. Our measured average total energy is slightly smaller than the one deduced previously and present in evaluated data. From this we conclude that the Pu239(nth,f) reaction may be ruled out as possible source of γ heating underestimation, when compared with benchmark calculations based on existing nuclear data.
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6.
  • Ledoux, X., et al. (författare)
  • The Neutrons for Science Facility at SPIRAL-2
  • 2018
  • Ingår i: Radiation Protection Dosimetry. - : OXFORD UNIV PRESS. - 0144-8420 .- 1742-3406. ; 180:1-4, s. 115-119
  • Tidskriftsartikel (refereegranskat)abstract
    • The neutrons for science (NFS) facility is a component of SPIRAL-2, the new superconducting linear accelerator built at GANIL in Caen (France). The proton and deuteron beams delivered by the accelerator will allow producing intense neutron fields in the 100 keV-40 MeV energy range. Continuous and quasi-mono-kinetic energy spectra, respectively, will be available at NFS, produced by the interaction of a deuteron beam on a thick Be converter and by the Li-7(p, n) reaction on thin converter. The pulsed neutron beam, with a flux up to two orders of magnitude higher than those of other existing time-of-flight facilities, will open new opportunities of experiments in fundamental research as well as in nuclear data measurements. In addition to the neutron beam, irradiation stations for neutron-, proton- and deuteron-induced reactions will be available for cross-sections measurements and for the irradiation of electronic devices or biological cells. NFS, whose first experiment is foreseen in 2018, will be a very powerful tool for physics, fundamental research as well as applications like the transmutation of nuclear waste, design of future fission and fusion reactors, nuclear medicine or test and development of new detectors.
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7.
  • Ledoux, X., et al. (författare)
  • The neutrons for science facility at SPIRAL-2
  • 2017
  • Ingår i: ND 2016. - Les Ulis : EDP Sciences.
  • Konferensbidrag (refereegranskat)abstract
    • Numerous domains, in fundamental research as well as in applications, require the study of reactions induced by neutrons with energies from few MeV up to few tens of MeV. Reliable measurements also are necessary to improve the evaluated databases used by nuclear transport codes. This energy range covers a large number of topics like transmutation of nuclear waste, design of future fission and fusion reactors, nuclear medicine or test and development of new detectors. A new facility called Neutrons For Science (NFS) is being built for this purpose on the GANIL site at Caen (France). NFS is composed of a pulsed neutron beam for time-of-flight facility as well as irradiation stations for cross-section measurements. Neutrons will be produced by the interaction of deuteron and proton beams, delivered by the SPIRAL-2 linear accelerator, with thick or thin converters made of beryllium or lithium. Continuous and quasi-mono-energetic spectra will be available at NFS up to 40 MeV. In this fast energy region, the neutron flux is expected to be up to 2 orders of magnitude higher than at other existing time-of-flight facilities. In addition, irradiation stations for neutron-, proton- and deuteron-induced reactions will allow performing cross-section measurements by the activation technique. After a description of the facility and its characteristics, the experiments to be performed in the short and medium term will be presented.
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8.
  • Qi, L., et al. (författare)
  • Potential of prompt γ -ray emission studies in fast-neutron induced fission : a first step
  • 2020
  • Ingår i: European Physical Journal A. - : Springer Nature. - 1434-6001 .- 1434-601X. ; 56:3
  • Tidskriftsartikel (refereegranskat)abstract
    • Prompt γ-ray spectra emitted in fast-neutron induced fission of 239Pu have been recently measured by using the LICORNE directional neutron source at En = 1.8 MeV. The results are used in parallel with the measurements of fast-neutron induced fission of 238U and spontaneous fission of 252Cf to assess the potential of such reactions and observables, in contributing to the understanding of fission. The γ-ray spectra were measured and analyzed under similar conditions, allowing a consistent and robust comparison between the three systems. They are further compared to Monte–Carlo simulations based on two widely-used semi-empirical codes, FREYA and GEF. Differences in the low and high energy portions of the spectrum are interpreted based on simple arguments involving nuclear structure and evaporation effects. The significance and potential of experimental campaigns of this kind, as well as current limitations, are highlighted, together with straightforward but mandatory extensions.
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9.
  • Oberstedt, S., et al. (författare)
  • Prompt fission γ -ray spectrum characteristics from Pu 240 (sf) and Pu 242 (sf)
  • 2016
  • Ingår i: Physical Review C. - : American Physical Society (APS). - 2469-9985 .- 2469-9993. ; 93:5
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper we present first results for prompt fission γ-ray spectra (PFGS) characteristics from the spontaneous fission (sf) of Pu240 and Pu242. For Pu242(sf) we obtained, after proper unfolding of the detector response, an average energy per photon ϵγ=(0.843±0.012) MeV, an average multiplicity Mγ=(6.72±0.07), and an average total γ-ray energy release per fission Ēγ,tot = (5.66 ± 0.06) MeV. The Pu240(sf) emission spectrum was obtained by applying a so-called detector-response transformation function determined from the Pu242 spectrum measured in exactly the same geometry. The results are an average energy per photon ϵγ=(0.80±0.07) MeV, the average multiplicity Mγ = (8.2 ± 0.4), and an average total γ-ray energy release per fission Ēγ,tot = (6.6 ± 0.5) MeV. The PFGS characteristics for Pu242(sf) are in very good agreement with those from thermal-neutron-induced fission on Pu241 and scales well with the corresponding prompt neutron multiplicity. Our results in the case of Pu240(sf), although drawn from a limited number of events, show a significantly enhanced average multiplicity and average total energy, but may be understood from a different fragment yield distribution in Pu240(sf) compared to that of Pu242(sf).
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10.
  • Göök, A., et al. (författare)
  • Correlated mass, energy, and angular distributions from bremsstrahlung-induced fission of U 234 and Th 232 in the energy region of the fission barrier
  • 2017
  • Ingår i: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 96:4
  • Tidskriftsartikel (refereegranskat)abstract
    • The bremstrahlung-induced fission of U234 and Th232 has been studied at the superconducting Darmstadt linear accelerator (S-DALINAC) in the excitation energy region close to the fission barrier. Fission-fragment mass and total kinetic energy (TKE) distributions from U234 were studied for the first time in this energy region. The results have been analysed in terms of fission modes, and a dominant yield of the mass-asymmetric standard-2 mode was found in both nuclei. No strong dependence of the fission-mode weights on the excitation energy of the compound nucleus was found. Correlations among mass, TKE, and angular distributions have also been investigated. A correlation in the form of an increased anisotropy for far-asymmetric masses and low TKE were found in both fissioning systems. A possible interpretation of this correlation in terms of fission modes is discussed. 
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11.
  • Göök, A., et al. (författare)
  • Fragment characteristics from fission of U-238 and U-234 induced by 6.5-9.0 MeV bremsstrahlung
  • 2011
  • Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474 .- 1873-1554. ; 851:1, s. 1-16
  • Tidskriftsartikel (refereegranskat)abstract
    • Fission of U-238 and U-234 induced by bremsstrahlung of 6.5-9.0 MeV endpoint energy has been investigated at the superconducting Darmstadt electron linear accelerator S-DALINAC. Using a twin Frisch grid ionization chamber, fission-fragment energy and mass distributions have been determined by means of the double kinetic-energy technique. Results on the fission-fragment characteristics from U-238(gamma, f) are in agreement with results from the literature. In addition fission-fragment mass and energy distributions from U-234(gamma, f) are presented for the first time in this energy region. An analysis of fission modes within the Brosa model has been performed. The relative yield of the S 1 mode was found to be (13 +/- 3)% in U-234 and (35 +/- 2)% in U-238.
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12.
  • Göök, A., et al. (författare)
  • Photo-fission at the S-DALINAC
  • 2009
  • Ingår i: 4th international workshop on nuclear fission and fission-product spectroscopy. - : American Institute of Physics (AIP). - 9780735407145 ; , s. 351-354
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • Experiments on photo-induced fission of 238U and 234U using bremsstrahlung with endpoint energies between 6 MeV and 9 MeV have been carried out at the superconducting Darmstadt electron linear accelerator S-DALINAC. A twin Frisch grid ionization chamber has been used to determine energy and mass distributions via the 2E-technique. The fission fragment emission angle, which is used to correct for energy loss in the target and backing material for a correct determination of fragment energy and mass, is deduced from the time difference between cathode and anode signals. The research program including the foreseen search for parity violation in photo-induced fission and first experimental results will be presented. © 2009 American Institute of Physics.
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13.
  • Hambsch, F. -J, et al. (författare)
  • Investigation of the Fission Process at IRMM
  • 2011
  • Ingår i: Journal of the Korean Physical Society. - : Korean Physical Society. - 0374-4884 .- 1976-8524. ; 59:2, s. 1654-1659
  • Tidskriftsartikel (refereegranskat)abstract
    • The investigation of the fission process is and has been a major undertaking at IRMM. The most recent investigations concerned the reaction (234)U(n,f) and (238)U(n,f) around vibrational resonances at the barrier of the fission cross-section. Furthermore prompt neutron emission of (252)Cf(SF) has been investigated understanding for the first time the prompt neutron multiplicity as a function of total kinetic energy (TKE). Theoretical modelling of reaction cross sections as well as prompt neutron multiplicity and spectra has been performed using the experimental data as input parameters. Also instrument developments for correlation measurements of fission fragment properties has been pursued in recent years with the time-of-flight spectrometer VERDI and detectors for prompt fission gamma-ray.
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14.
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15.
  • Oberstedt, Andreas, et al. (författare)
  • Improved values for the characteristics of prompt-fission gamma-ray spectra from the reaction U-235(n(th), f)
  • 2013
  • Ingår i: Physical Review C. Nuclear Physics. - : American Physical Society. - 0556-2813 .- 1089-490X .- 2469-9985 .- 2469-9993. ; 87:5, s. 051602-
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper we present results from measurements of prompt gamma rays from the thermal neutron induced fission of U-235. Photons were measured in coincidence with fission fragments with cerium-doped LaCl3 and LaBr3 as well as CeBr3 scintillation detectors, which offer an intriguing combination of excellent timing resolution and good resolving power. The spectra measured with all employed detectors are in excellent agreement with respect to their shapes. Characteristic parameters were extracted for a gamma-energy range from 0.1 to 6.0 MeV and the results obtained with several detectors were averaged. From that, the average emission yield of prompt-fission gamma rays was determined to be (nu) over bar (gamma) = (8.19 +/- 0.11) per fission, the average energy per photon to be epsilon(gamma) = (0.85 +/- 0.02) MeV, and the total energy to be E-gamma,E-tot = (6.92 +/- 0.09) MeV. The uncertainties are much lower than the 7.5% requested for the modeling of advanced nuclear reactor cores. Estimating the influence of gamma rays with energies between 6 and 10 MeV on the values determined in this work revealed a negligible deviation of the order of the found uncertainties.
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16.
  • Oberstedt, A., et al. (författare)
  • Time response and its impact on prompt fission gamma-ray spectra characteristics
  • 2020
  • Ingår i: European Physical Journal A. - : Springer Nature. - 1434-6001 .- 1434-601X. ; 56:7
  • Tidskriftsartikel (refereegranskat)abstract
    • The time dependence of prompt gamma-ray spectral characteristics, in particular themultiplicity, was studied during the first 10 ns after the spontaneous fission of Cf-252. The impact of prompt window and experimental time resolution on the determination of prompt multiplicities is assessed and described mathematically. As a consequence we are able to offer corrections that allow a reliable comparison of results from different measurements. An apparent discrepancy between a theoretical and an experimentally found time dependence is explained by the influence of a finite experimental timing resolution as well as the choice of the prompt timing window.
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17.
  • Oberstedt, S., et al. (författare)
  • Correlation measurements of fission-fragment properties
  • 2010
  • Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2100-014X.
  • Konferensbidrag (refereegranskat)abstract
    • For the development of future nuclear fission applications and for a responsible handling of nuclear waste the a-priori assessment of the fission-fragments' heat production and toxicity is a fundamental necessity. The success of an indispensable modelling of the fission process strongly depends on a good understanding of the particular mechanism of scission, the mass fragmentation and partition of excitation energy. Experimental observables are fission-fragment properties like mass- and energy-distributions, and the prompt neutron as well as γ-ray multiplicities and emission spectra. The latter quantities should preferably be known as a function of fragment mass and excitation energy. Those data are highly demanded as published by the OECD-NEA in its high priority data request list. With the construction of the double (v, E) spectrometer VERDI we aim at measuring pre- and post-neutron masses directly and simultaneously to avoid prompt neutron corrections. From the simultaneous measurement of pre- and post-neutron fission-fragment data the prompt neutron multiplicity may then be inferred fully correlated with fragment mass yield and total kinetic energy. Using an ultra-fast fission event trigger spectral prompt fission γ-ray measurements may be performed. For that purpose recently developed lanthanum-halide detectors, with excellent timing characteristics, were coupled to the VERDI spectrometer allowing for a very good discrimination of fission γ-rays and prompt neutrons due to their different time-of-flight.
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18.
  • Piau, V., et al. (författare)
  • Neutron and gamma multiplicities calculated in the consistent framework of the Hauser-Feshbach Monte Carlo code FIFRELIN
  • 2023
  • Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 837
  • Tidskriftsartikel (refereegranskat)abstract
    • Monte-Carlo simulations to calculate the number of prompt particles emitted during fission were performed using the FIFRELIN code and compared to recent experimental data. We show that we are able to reproduce both the neutron and gamma-ray multiplicity distributions as a function of the pre-neutron mass of the fission fragments using a single consistent set of parameters. This result was made possible by using an energy-dependent spin cut-off model, driving the initial total angular momentum of the fission fragments, together with microscopic level densities from the HFB plus combinatorial method. We also discuss, how the initial excitation-energy sharing shapes the TKE-dependent gamma-ray multiplicity.(c) 2022 French Alternative Energies and Atomic Energy Commission (CEA). Published by Elsevier B.V.This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP3.
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19.
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20.
  • Dragić, A.L., et al. (författare)
  • Shape-isomer studies with resonance neutron capture
  • 2014
  • Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3884 .- 1875-3892. ; 59:C, s. 125-131
  • 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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21.
  • Eckardt, C., et al. (författare)
  • Development of an Active 238UF6 Gas Target
  • 2012
  • Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3884 .- 1875-3892. ; 31, s. 141-146
  • 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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22.
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23.
  • Gomez L, Ana Maria, 1993-, et al. (författare)
  • Determination of the Plasma Delay Time in PIPS detectors for fission fragments at the LOHENGRIN spectrometer
  • 2023
  • Ingår i: 15<sup>th</sup> International Conference on Nuclear Data for Science and Technology (ND2022). - : EDP Sciences.
  • Konferensbidrag (refereegranskat)abstract
    • The VElocity foR Direct particle Identification spectrometer (VERDI) is a 2E-2v fission spectrometer that allows the measurement of the total mass distribution of secondary fission fragments with a resolving power of 1-2 u. It consists of two time-of-flight (ToF) arms, with one Micro Channel Plate (MCP) detector and up to 32 Silicon PIPS (Passive Implanted Planar Silicon) detectors per arm. The MCPs provide the start timing signals and the PIPS detectors provide both the energy and the stopping ToF signals. In real conditions, the PIPS signals are affected by the formation of plasma from the interaction between the heavy ions and the detector material. The plasma contributes to a reduction in signal amplitude, resulting in a Pulse Height Defect (PHD), and introduces a signal delay, known as Plasma Delay Time (PDT). An experiment to characterize the PDT and PHD was performed at the LOHENGRIN recoil separator of the Institut Laue Langevin (ILL). Characteristic fission fragments from the 239Pu(n,f) reaction were separated based on their A/Q and E/Q ratios, allowing the measurement of a wide range of energies from 21 to 110 MeV and masses between 80 and 149 u. Six PIPS detectors were characterized to study their individual responses to the PDT and PHD effects. The signals were recorded in a digital acquisition system to completely exploit the offline analysis capabilities. Achieved combined timing and energy resolutions for fission fragments varied between 72(2) ps and 100(4) ps and 1.4% - 2% (FWHM), respectively. Preliminary PHD and PDT data are presented from the masses A=85, 95, 130 and 143. The PHD trends are strongly correlated with both the ion energy and mass. The PDT, on the other hand, shows a strong variation as a function of the ion kinetic energy but a smaller dependence on the ion mass.
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24.
  • Göök, A., et al. (författare)
  • Application of the ShockleyRamo theorem on the grid inefficiency of Frisch grid ionization chambers
  • 2012
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 664:1, s. 289-293
  • Tidskriftsartikel (refereegranskat)abstract
    • The concept of grid inefficiency in Frisch grid ionization chambers and its influence on the anode pulse shape is explained in terms of the ShockleyRamo theorem for induced charges. The grid inefficiency correction is deduced from numerically calculated weighting potentials. A method to determine the correction factor experimentally is also presented. Experimental and calculated values of the correction factor are shown to be in good agreement. 
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25.
  • Göök, A., et al. (författare)
  • Particle emission angle determination in Frisch grid ionization chambers by electron drift-time measurements
  • 2010
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 621:1-3, s. 401-405
  • Tidskriftsartikel (refereegranskat)abstract
    • The double kinetic energy measurement of fission fragments with a double-sided Frisch grid ionization chamber allows a careful determination of the emission angle, which is essential in order to apply appropriate energy-loss corrections. We present a drift-time method, which uses the time that free electrons need to drift from the location of their creation, e.g. by a fission fragment in the counting gas, to the grid, before inducing a signal on the anode. Such a measurement leaves energy and angular information fully decoupled. We demonstrate the applicability of the drift-time method for the example of the 234,238U (γ,f) reactions performed at the superconducting Darmstadt electron linear accelerator. The angular resolutions achieved with this method are comparable to those obtained with other methods.
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26.
  • Hambsch, F.-J., F. Tovesson, S. Oberstedt, V. Frisch, A. Oberstedt, B. Fogelberg, and E. Ramström (författare)
  • First measurement of the 233Pa Fission Cross Section.
  • 2003
  • Ingår i: 10th International Seminar on Interaction of Neutrons with Nuclei. Neutron Spectroscopy, Nuclear Structure, Related Topics, 2003 202. ; , s. 202-
  • Konferensbidrag (refereegranskat)
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27.
  • Hambsch, F. -J, et al. (författare)
  • Fission Fragment Yield, Cross Section and Prompt Neutron and Gamma Emission Data from Actinide Isotopes
  • 2014
  • Ingår i: Nuclear Data Sheets. - : Elsevier BV. - 0090-3752 .- 1095-9904. ; 119, s. E38-E41
  • Tidskriftsartikel (refereegranskat)abstract
    • Recent experimental investigations on major and minor actinides at the JRC-IRMM are presented. Fission-fragment distributions of isotopes with vibrational resonances in the sub-threshold fission cross section, i. e. U-234,U-238, have been measured. For U-234, the impact of an increased neutron multiplicity for the heavy fragments with higher incident neutron energies has been studied as observed in experiment and also recently theoretically predicted. The impact is found to be noticeable on post-neutron mass yields, which are the relevant quantities for a-priori waste assessments. The fission cross sections for Pu-240,Pu-242 at threshold and in the plateau region are being investigated within the ANDES project. The results show some discrepancies to the ENDF/B-VII. 1 evaluation mainly for Pu-242 around 1 MeV, where the evaluation exhibits a resonance-like structure not observed so clearly in the present work. The requested target accuracy in design studies of innovative reactor concepts like Gen-IV is in the range of a few percent. In order to be able to respond to requests for measurements of prompt neutron and gamma-ray emission in fission JRC-IRMM has also invested in setting up a neutron and gamma-ray detector array. The neutron array is called SCINTIA and has so far been tested with Cf-252(SF). For gamma-ray multiplicity and spectrum measurements of Cf-252(SF) and U-235(n(th), f) lanthanum- and cerium-halide detectors were successfully used.
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28.
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29.
  • Oberstedt, S., et al. (författare)
  • First results on the neutron-induced fission cross-section of Pa-231 for incident neutron energies E-n > 17 MeV
  • 2012
  • Ingår i: Annals of Nuclear Energy. - : Elsevier. - 0306-4549 .- 1873-2100. ; 43, s. 26-30
  • Tidskriftsartikel (refereegranskat)abstract
    • First results on the neutron-induced fission cross-section of Pa-231 for incident neutron energies E-n > 17 MeV are presented. The experiments were carried out with quasi mono-energetic neutrons produced in the reaction T(d, n)He-4. Corrections for low-energy neutron background produced in this reaction at incident deuteron energies E-d > 2 MeV are taken into account and based on experimental data obtained by two different techniques. Despite the relatively large error bars at the higher neutron energies, the new cross-section values meet the accuracy requirements set by the IAEA and will allow to remove the hitherto existing large spread between different previously published data. Recent cross-section calculations describe well the new experimental results, which are in consistency with cross-section values obtained in a particle-transfer reaction at excitation energies corresponding to neutron energies E-n < 10 MeV. 
  •  
30.
  • Oberstedt, S., et al. (författare)
  • High-precision prompt-gamma-ray spectral data from the reaction Pu-241(n(th), f)
  • 2014
  • Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 90:2, s. Art. no. 024618-
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper we present results from the first high-precision prompt-gamma-ray spectral measurements from the reaction Pu-241(n(th), f). Apart from one recent experiment, no data are reported in the literature for this fissioning system, which motivated a new dedicated experiment. We have measured prompt-fission gamma rays with three cerium-doped LaBr3 (two 5.08 cm x 5.08 cm and one 7.62 cm x 7.62 cm) and one CeBr3 (5.08 cm x 5.08 cm) scintillation detectors, which all exhibit excellent timing and good energy resolution. The average gamma-ray multiplicity was determined to be (nu) over bar (gamma) = (8.21 +/- 0.09) per fission, the average energy to be epsilon(gamma) = (0.78 +/- 0.01) MeV, and the total energy to be E-gamma,E-tot = (6.41 +/- 0.06) MeV as the weighted average from all detectors. Since the results from all detectors are in excellent agreement, and the total released gamma energy is modestly higher than the one in the present evaluated nuclear data files, we suspect that the underestimation of the prompt-gamma heating in nuclear reactors is due to fast-neutron-induced fission on U-238 or rather from fission induced by gamma rays from neutron capture in the construction material.
  •  
31.
  • Oberstedt, S., et al. (författare)
  • New Prompt Fission gamma-ray Data in Response to the OECD/NEA High Priority Request
  • 2014
  • Ingår i: Nuclear Data Sheets. - : Elsevier BV. - 0090-3752 .- 1095-9904. ; 119, s. E225-E228
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper we report about new prompt fission gamma-ray measurements, which we have performed with highly efficient gamma-ray detectors based on lanthanide-halide crystals, aiming at very fast timing in conjunction with a good energy resolution. About four decades after the experiments were performed, whose results are still used for current evaluations, we present new spectral prompt fission gamma-ray data from the reactions Cf-252(SF) and U-235(n(th),f). Based on our new findings we recommend to replace the current ENDF/B-VII. 1 evaluation for Cf-252(SF) and U-235(n(th),f) as well as to perform new measurements for U-238(n,f) and Pu-241(n,f).
  •  
32.
  • Oberstedt, S., et al. (författare)
  • Prompt fission gamma-ray spectra characteristics - a first summary
  • 2015
  • Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3884 .- 1875-3892. ; 64, s. 83-90
  • Konferensbidrag (refereegranskat)abstract
    • In this work we give an overview of our investigations of prompt gamma-ray emission in nuclear fission. This work was conducted during the last five years in response to a high priority nuclear data request formulated by the OECD/NEA. The aim was to reveal data deficiencies responsible for a severe under-prediction of the prompt gamma heating in nuclear reactor cores. We obtained new prompt fission gamma-ray spectral (PFGS) data for Cf-252(SF) as well as for thermal-neutron induced fission on U-235(nth,f) and Pu-241(nth,f). In addition, first PFGS measurements with a fast-neutron beam were accomplished, too. The impact of the new data and future data needs are discussed.
  •  
33.
  • Tovesson, Fredrik, et al. (författare)
  • 233Pa(n, f) cross section up to En=8.5 MeV
  • 2004
  • Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474 .- 1873-1554. ; 733:1-2, s. 3-19
  • Tidskriftsartikel (refereegranskat)abstract
    • The energy dependence of the neutron-induced fission cross section of 233Pa has been measured directly for the first time from the fission threshold up to En=8.5 MeV. This reaction plays an important role in the thorium-uranium fuel cycle, and is thus of interest for the design and modeling of advanced reactor and transmutation facilities. The existing information in the ENDF/B-VI and JENDL-3.3 evaluated nuclear data files differ by a factor of two for the 233Pa(n, f) cross section values and show different fission threshold energies. Our new experimental data give lower cross section values than both evaluations and resolves the question about the threshold energy. In addition to the experimental investigation, also a new theoretical calculation of the reaction cross section has been performed with the statistical model code STATIS, showing a good agreement with the experimental data.
  •  
34.
  •  
35.
  • Tovesson, F., Hambsch, F.-J., Oberstedt, A., Fogelberg, B., Ramström, E. and Oberstedt, S. (författare)
  • The Pa-233 Fission Cross Section
  • 2002
  • Ingår i: Proc.of the Int.conf. on Nuclear Data for Science and Technology, Oct.7-12, 2001, Tsukuba, Japan. Journal of Nuclear Science and Technology, Supplement 2, (August 2002) 210.
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)
  •  
36.
  •  
37.
  • Tovesson, F., V.Fritsch, F.-J.Hambsch, S.Oberstedt, A.Oberstedt, B.Fogelberg, E.Ramstrom (författare)
  • The 233Pa fission cross-section
  • 2003
  • Ingår i: IRMM Neutron Physics Unit 2002 Scientific Report; EUR 20684 EN.
  • Annan publikation (övrigt vetenskapligt/konstnärligt)
  •  
38.
  • Travar, M., et al. (författare)
  • Experimental information on mass- and TKE-dependence of the prompt fission gamma-ray multiplicity
  • 2021
  • Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 817, s. 136293-
  • Tidskriftsartikel (refereegranskat)abstract
    • Prompt gamma rays from the spontaneous fission of Cf-252 were measured with cerium-doped LaBr3 detectors. The average prompt fission gamma-ray multiplicity, M-gamma, was determined as a function of fragment mass number (A) and total kinetic energy (TKE). High-statistics data, obtained from three detectors of different size at different angles relative to the fission chamber, confirms unequivocally a saw-tooth like shape of the gamma multiplicity as a function of fragment mass, in contrast to previously published data. In addition, the TKE-dependence of M-gamma was determined experimentally and compared with recent data.
  •  
39.
  • Vladuca, G., et al. (författare)
  • Calculation of the neutron-induced fission cross section of 233Pa
  • 2004
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 69:2, s. 021604-
  • Tidskriftsartikel (refereegranskat)abstract
    • Since very recently, experimental data for the energy dependence of the 233Pa(n,f) cross section are finally available. This has stimulated a new, self-consistent cross section evaluation for the system n+233Pa in the incident neutron energy range 0.01–6 MeV. The results are quite different compared to earlier evaluation attempts. Since 233Pa is an important intermediary in the thorium based fuel cycle, its neutron reaction cross sections are key parameters in the modeling of future advanced reactor concepts.
  •  
40.
  • Vladuca, G., et al. (författare)
  • Calculation of the neutron-induced fission cross section of 233Pa up to 20 MeV
  • 2004
  • Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474 .- 1873-1554. ; 740:1-2, s. 3-19
  • Tidskriftsartikel (refereegranskat)abstract
    • Since very recently, direct measurements of the 233Pa(n,f) cross-section are available in the energy range from 1.0 to 8.5 MeV. This has stimulated a new, self-consistent, neutroncross-section evaluation for the n+233Pa system, in the incident neutron energy range 0.01–20MeV. Since higher fission chances are involved also the lighter Pa-isotopes had to be re-evaluated in a consistent manner. The results are quite different compared to earlier evaluation attempts. Since 233Pa is a key isotope in the thorium based fuel cycle the quality of its reaction cross-sections is important for the modeling of future advanced fuel and reactor concepts. The present status of the evaluated libraries is that they differ by a factor of two in the absolute fissioncross-section and also in the threshold energy value.
  •  
41.
  • Al-Adili, Ali, et al. (författare)
  • Analysis of prompt fission neutrons in U-235(nth,f) and fission fragment distributions for the thermal neutron induced fission of U-234
  • 2016
  • Ingår i: CNR*15 - 5th International Workshop On Compound-Nuclear Reactions And Related Topics. - : EDP Sciences.
  • Konferensbidrag (refereegranskat)abstract
    • This paper presents the ongoing analysis of two fission experiments. Both projects are part of the collaboration between the nuclear reactions group at Uppsala and the JRC-IRMM. The first experiment deals with the prompt fission neutron multiplicity in the thermal neutron induced fission of U-235(n,f). The second, on the fission fragment properties in the thermal fission of U-234(n,f). The prompt fission neutron multiplicity has been measured at the JRC-IRMM using two liquid scintillators in coincidence with an ionization chamber. The first experimental campaign focused on U-235(nth,f) whereas a second experimental campaign is foreseen later for the same reaction at 5.5 MeV. The goal is to investigate how the so-called saw-tooth shape changes as a function of fragment mass and excitation energy. Some harsh experimental conditions were experienced due to the large radiation background. The solution to this will be discussed along with preliminary results. In addition, the analysis of thermal neutron induced fission of U-234(n,f) will be discussed. Currently analysis of data is ongoing, originally taken at the ILL reactor. The experiment is of particular interest since no measurement exist of the mass and energy distributions for this system at thermal energies. One main problem encountered during analysis was the huge background of U-235(nth, f). Despite the negligible isotopic traces in the sample, the cross section difference is enormous. Solution to this parasitic background will be highlighted.
  •  
42.
  • Al-Adili, Ali, et al. (författare)
  • Neutron-multiplicity experiments for enhanced fission modelling
  • 2017
  • Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 9782759890200
  • Konferensbidrag (refereegranskat)abstract
    • The nuclear de-excitation process of fission fragments (FF) provides fundamental information for the understanding of nuclear fission and nuclear structure in neutron-rich isotopes. The variation of the prompt-neutron multiplicity, ν(A), as a function of the incident neutron energy (En) is one of many open questions. It leads to significantly different treatments in various fission models and implies that experimental data are analyzed based on contradicting assumptions. One critical question is whether the additional excitation energy (Eexc) is manifested through an increase of ν(A) for all fragments or for the heavy ones only. A systematic investigation of ν(A) as a function of En has been initiated. Correlations between prompt-fission neutrons and fission fragments are obtained by using liquid scintillators in conjunction with a Frisch-grid ionization chamber. The proof-of-principle has been achieved on the reaction 235U(nth,f) at the Van De Graff (VdG) accelerator of the JRC-Geel using a fully digital data acquisition system. Neutrons from 252Cf(sf) were measured separately to quantify the neutron-scattering component due to surrounding shielding material and to determine the intrinsic detector efficiency. Prelimenary results on ν(A) and spectrum in correlation with FF properties are presented.
  •  
43.
  • Bergmann, U. C., et al. (författare)
  • On the beta-decay of C-9
  • 2001
  • Ingår i: Nuclear Physics A. - 0375-9474. ; 692:3-4, s. 427-450
  • Tidskriftsartikel (refereegranskat)abstract
    • In beta -decay experiments on C-9 at CERN/ISOLDE the beta -strength was determined to the ground state, the 12.2 MeV excited state and the Isobaric Analog State (IAS) at 14.655 MeV in B-9. A large beta -strength asymmetry is deduced for the mirror transitions of C-9 and Li-9 to states around 12 MeV excitation energy. A satisfactory description of the three-body decay from a narrow energy region around the 12.2 MeV resonance is obtained within a sequential model involving the ground and first-excited states of Li-5 and Be-8. From the study of angular correlations the spin of the 12.2 MeV state is determined as 5/2(-). For the first time the population of the IAS is observed in beta -decay and new information on the decay of this state is obtained. The advantages of a closely packed. highly segmented detector setup are demonstrated. (C) 2001 Elsevier Science B.V. All rights reserved.
  •  
44.
  •  
45.
  • Göök, A., et al. (författare)
  • Prompt neutrons in correlation with fission fragments from U 235 (n,f)
  • 2018
  • Ingår i: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 98:4
  • Tidskriftsartikel (refereegranskat)abstract
    • Improved knowledge of prompt emission in fission has significant implications for our understanding of the fission process. It is also important for improving nuclear data evaluation, with impact on applications. The correlation between prompt neutrons and fragments emitted in binary neutron induced fission of U235 has been studied at the GELINA facility. The experiment employs an array of proton recoil scintillators and a position-sensitive twin ionization chamber. This experimental arrangement permits measurement of the correlations between neutron emission, fragment angle, and mass and energy of the fission fragments. In this article, we present results on prompt fission neutron energy and multiplicity correlations with mass and total kinetic energy of the fission fragments. Results from the present measurement shows distinct differences compared to earlier studies of the correlated fission fragment and prompt neutron emission quantities. The differences with respect to earlier investigations are interpreted as improved fission fragment energy resolution in the present measurement. The present result supports several recent model calculations of prompt neutron and fission fragment correlations. 
  •  
46.
  • Hambsch, F. -J, et al. (författare)
  • Prompt Neutron Emission Correlations with Fission Fragment Properties
  • 2018
  • Ingår i: Fission And Properties Of Neutron-Rich Nuclei. - : World Scientific. - 9789813229433 ; , s. 503-512
  • Konferensbidrag (refereegranskat)abstract
    • The investigation of the dynamics of the nuclear fission process has been a standing research topic at the JRC-Geel during the past decades. Recently the focus was put on the de-excitation of fission fragments through the emission of prompt neutrons and gamma-rays. To this end new detector systems were developed at JRC-Geel, e.g. a position sensitive ionization chamber used in conjunction with the neutron scintillator array SCINTIA. The array has been tested using the spontaneous fission of Cf-252. The goal is to study correlations of fission fragments with prompt neutron emission in the resolved resonance region. No strong fluctuations of the average prompt neutron multiplicity for the strongest resonances in U-235 were observed. From the present data the mass-dependent neutron multiplicity, v(A), was generated. The v(A) distribution shows a more pronounced dip around the doubly magic mass A = 132 and at very low masses around A similar to 80 compared to the literature. In addition, a steeper slope for v(TKE) is observed. Cross checking with fragment data clearly shows a narrower mass and total kinetic energy (TKE) distribution. The 2E-2v spectrometer VERDI (VElocity foR Direct mass Identification) became operational. For Cf-252(sf) superior mass resolution is observed compared to a twin Frisch-grid ionization chamber. For post-neutron mass distributions still some issues need to be solved and v(A), being the difference of pre- and post-neutron mass distributions, is still deviating from literature data. Eventually, VERDI will provide a complementary measurement technique to assess v(A) and v(TKE). In addition, an experimental campaign to measure v(A) as a function of incident neutron energy for different actinides has been started. First tests show promising results.
  •  
47.
  • Jansson, Kaj, 1987-, et al. (författare)
  • The impact of neutron emission on correlated fission data from the 2E-2v method
  • 2018
  • Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 54
  • Tidskriftsartikel (refereegranskat)abstract
    • The double-energy double-velocity (2E-2v) method allows assessing fission-fragment mass yields prior to and after prompt neutron emission with high resolution. It is, therefore, considered as a complementary technique to assess average prompt neutron multiplicity as a function of fragment properties. We have studied the intrinsic features of the 2E-2v method by means of event-wise generated fission-fragment data and found short-comings in the method itself as well as in some common practices of application. We find that the 2E-2v method leads to large deviations in the correlation between the prompt neutron multiplicity and pre-neutron mass, which deforms and exaggerates the so-called “sawtooth” shape of nubar(A). We have identified the treatment of prompt neutron emission from the fragments as the origin of the problem. The intrinsic nature of this deficiency risks to render 2E-2v experiments less interesting. We suggest a method to correct 2E-2v data that can even be applied on existing measurements.
  •  
48.
  • Salvador-Castiñeira, P., et al. (författare)
  • Neutron-induced fission cross section of Pu 240 from 0.5 MeV to 3 MeV
  • 2015
  • Ingår i: Physical Review C. Nuclear Physics. - : American Physical Society (APS). - 0556-2813 .- 1089-490X. ; 92:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Pu240 has recently been pointed out by a sensitivity study of the Organization for Economic Cooperation and Development (OECD) Nuclear Energy Agency (NEA) to be one of the isotopes whose fission cross section lacks accuracy to meet the upcoming needs for the future generation of nuclear power plants (GEN-IV). In the High Priority Request List (HPRL) of the OECD, it is suggested that the knowledge of the Pu240(n,f) cross section should be improved to an accuracy within 1-3 %, compared to the present 5%. A measurement of the Pu240 cross section has been performed at the Van de Graaff accelerator of the Joint Research Center (JRC) Institute for Reference Materials and Measurements (IRMM) using quasi-monoenergetic neutrons in the energy range from 0.5 MeV to 3 MeV. A twin Frisch-grid ionization chamber (TFGIC) has been used in a back-to-back configuration as fission fragment detector. The Pu240(n,f) cross section has been normalized to three different isotopes: Np237(n,f), 235U(n,f), and 238U(n,f). Additionally, the secondary standard reactions were benchmarked through measurements against the primary standard reaction 235U(n,f) in the same geometry. A comprehensive study of the corrections applied to the data and the associated uncertainties is given. The results obtained are in agreement with previous experimental data at the threshold region. For neutron energies higher than 1 MeV, the results of this experiment are slightly lower than the ENDF/B-VII.1 evaluation, but in agreement with the experiments of Laptev et al. (2004) as well as Staples and Morley (1998).
  •  
49.
  • Salvador-Castiñeira, P., et al. (författare)
  • Neutron-induced fission cross sections of Pu 242 from 0.3 MeV to 3 MeV
  • 2015
  • Ingår i: Physical Review C. Nuclear Physics. - : American Physical Society. - 0556-2813 .- 1089-490X. ; 92:4
  • Tidskriftsartikel (refereegranskat)abstract
    • The majority of the next generation of nuclear power plants (GEN-IV) will work in the fast-neutron-energy region, as opposed to present day thermal reactors. This leads to new and more accurate nuclear-data needs for some minor actinides and structural materials. Following those upcoming demands, the Organisation for Economic Cooperation and Development Nuclear Energy Agency performed a sensitivity study. Based on the latter, an improvement in accuracy from the present 20% to 5% is required for the Pu242(n,f) cross section. Within the same project both the Pu240(n,f) cross section and the Pu242(n,f) cross section were measured at the Van de Graaff accelerator of the Joint Research Centre at the Institute for Reference Materials and Measurements, where quasimonoenergetic neutrons were produced in an energy range from 0.3 MeV up to 3 MeV. A twin Frisch-grid ionization chamber has been used in a back-to-back configuration as fission-fragment detector. The Pu242(n,f) cross section has been normalized to three different isotopes: Np237(n,f), U235(n,f), and U238(n,f). A comprehensive study of the corrections applied to the data and the uncertainties associated is given. The results obtained are in agreement with previous experimental data at the threshold region up to 0.8 MeV. The resonance-like structure at 0.8 to 1.1 MeV, visible in the evaluations and in most previous experimental values, was not reproduced with the same intensity in this experiment. For neutron energies higher than 1.1 MeV, the results of this experiment are slightly lower than the Evaluated Nuclear Data File/B-VII.1 evaluation but in agreement with the experiment of Tovesson et al. (2009) as well as Staples and Morley (1998). Finally, for energies above 1.5 MeV, the results show consistency with the present evaluations. 
  •  
50.
  • Sardet, A., et al. (författare)
  • Experimental studies of prompt fission neutron energy spectra
  • 2013
  • Ingår i: Physics Procedia: Scientific Workshop on Nuclear Fission Dynamics and the Emission of Prompt Neutrons and Gamma Rays, THEORY-2 2012; Biarritz; France; 28 November 2012 through 30 November 2012. - : Elsevier BV. ; 47, s. 144-149
  • Konferensbidrag (refereegranskat)abstract
    • Prompt fission neutron spectra were measured in the reactions 238U(n, f), 235U(n, f) and 237Np(n, f) at different incident neutron energies. The neutrons were detected using a coaxial doped p-terphenyl scintillation detector in coincidence with fission fragments and their time-of-flight was recorded. The properties of the neutron detector were determined and the results are presented in this work. A preliminary neutron detection efficiency was applied to data from the neutron-induced fission of 238U at En = 5.2 MeV, leading to encouraging results.
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