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Sökning: WFRF:(Oberstedt Andreas)

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1.
  • 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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2.
  • Billnert, Robert, 1981, et al. (författare)
  • New information on the characteristics of 1 in. x 1 in. cerium bromide scintillation detectors
  • 2011
  • Ingår i: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 647:1, s. 94-99
  • Tidskriftsartikel (refereegranskat)abstract
    • In view of highly demanded new and accurate data on prompt gamma-ray emission in nuclear fission a major part of investigations is directed towards the selection of suitable detector systems. Here we have studied a new type of crystal scintillation detectors made from cerium bromide (CeBr(3)). For the first time a full characterization of such a detector is presented in terms of energy resolution, pulse-height linearity, intrinsic activity and intrinsic timing resolution. In particular the latter one is very important for prompt fission gamma-ray studies, because the presence of fast neutrons, emitted in fission too, requires the time-of-flight method for their discrimination. The energy resolution has been found to be comparable to that of cerium-doped LaCl(3):Ce detectors at an efficiency comparable to the one of a LaBr(3):Ce detector of the same size. The intrinsic activity of the CeBr(3) crystal was observed to be much lower compared to lanthanum halide crystals. The intrinsic timing resolution of a coaxial 1 in. x 1 in. sized detector was measured relative to that of a previously characterized LaCl(3):Ce detector and found to be (326 +/- 7) Ps at (60)Co energies, which is in between those of a LaBr(3):Ce and a LaCl(3):Ce detector of same size.
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3.
  • Billnert, Robert, 1981, et al. (författare)
  • New prompt spectral gamma-ray data from the reaction Cf-252(sf) and its implication on present evaluated nuclear data files
  • 2013
  • Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 87:2
  • 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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4.
  • Billnert, Robert, 1981, et al. (författare)
  • Novel Scintillation Detectors for Prompt Fission γ-Ray Measurements
  • 2012
  • Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3884 .- 1875-3892. ; 31, s. 29-34
  • 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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5.
  • Billnert, R., et al. (författare)
  • Prompt γ-ray spectral data from 252Cf(SF), 235U(nth, f) and 241Pu(nth,f)
  • 2014
  • Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3884 .- 1875-3892. ; 59:C, s. 17-23
  • 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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6.
  • Birgersson, Evert, et al. (författare)
  • Binary fission-fragment yields from the reaction 251Cf(nth, f)
  • 2005
  • Ingår i: Nuclear fission and fission-product spectroscopy. - : American Institute of Physics. - 0735402884 ; , s. 349-352
  • Konferensbidrag (refereegranskat)abstract
    • The recoil mass spectrometer LOHENGRIN of the Laue-Langevin Institute, Grenoble has been used to measure the light fission-fragment mass yield and kinetic energy distributions from neutron-induced 252Cf*, using 251Cf as target material. ©2005 American Institute of Physics
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7.
  • Birgersson, Evert, 1974- (författare)
  • Determination of binary fission-fragment yields in the reaction 251Cf(nth, f) and Verification of nuclear reaction theory predictions of fission-fragment distributions in the reaction 238U(n, f)
  • 2007
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Neutron-induced fission has been studied at different excitation energies of the compound nucleus by measurements on the two fissioning systems, 252Cf* and 239U*.For the first time, the light fission fragment yields from the reaction 251Cf(nth, f) have been measured with high resolution. This experiment was performed with the recoil mass spectrometer LOHENGRIN at ILL in Grenoble, France. When the results from this work, where the compound nucleus is at thermal excitation, are compared to the spontaneous fission of 252Cf, enhanced emission yields as well as an increased mean kinetic energy is observed around A = 115. This suggests the existence of an additional super-deformed fission mode in 252Cf.The reaction 238U(n, f) was studied using the 2E-technique with a double Frisch grid ionization chamber. Fission fragment mass, energy and angular distributions were determined for incident neutron energies between 0.9 and 2.0 MeV. The experiments were performed at the Van de Graaff accelerator of IRMM in Geel, Belgium. This is the first measurement of the mass distribution for incident neutron energies around 0.9 MeV. The motivation for studying 238U(n, f) was to verify theoretical predictions of the mass distribution at the vibrational resonance in the fission cross section at 0.9 MeV. However, the predicted changes in fission fragment distributions could not be confirmed.A precise modelling of the fission process for the minor actinides becomes very important for future generation IV and accelerator driven nuclear reactors. Since fission fragment distributions depend on the excitation of the fissioning system, so does the number of delayed neutrons, which are one of the safety parameters in a reactor.
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8.
  • Birgersson, Evert, et al. (författare)
  • Light fission-fragment mass distribution from the reaction 251Cf(nth, f)
  • 2007
  • Ingår i: Nuclear Physics A. - Amsterdam : Elsevier. - 0375-9474 .- 1873-1554. ; 791:1-2, s. 1-23
  • Tidskriftsartikel (refereegranskat)abstract
    • For mass numbers A = 80 to 124 the recoil mass spectrometer LOHENGRIN of the Institute Laue-Langevin in Grenoble was used to measure with high resolution the light fission-fragment mass yields and kinetic energy distributions from thermal-neutron induced fission of 252Cf* for the first time, using 251Cf as target material. The obtained mean light fragment mass AL = (107 ± 2) and the corresponding mean kinetic energy Ek,L = (103±2) MeV are within the expected trend. Emission yields around A = 115 are enhanced and the corresponding mean kinetic energy is higher compared to spontaneous fission of 252Cf. This could be explained by the existence of an additional super-deformed fission mode.
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9.
  • Birgersson, Evert, et al. (författare)
  • Properties of the reaction 238U(n, f) at the vibrational resonances
  • 2009
  • Ingår i: Nuclear Physics A. - Amsterdam : Elsevier. - 0375-9474 .- 1873-1554. ; 817:1-4, s. 1-34
  • Tidskriftsartikel (refereegranskat)abstract
    • Recent fission cross-section calculations for the reaction 238U(n, f ), based on an extended statistical model, predict a significant change of fission fragment properties, such as the mean mass by A = 1.5 and a notable increase in total kinetic energy in the region of the vibrational resonance at an incident neutron energy En = 0.9 MeV. This model includes individual fission cross-sections by the asymmetric standard 1 (S1) and standard 2 (S2) as well as the symmetric super-long (SL) mode. In order to verify the model predictions, a dedicated experiment on 238U has been carried out to measure fission-fragment mass yield distributions for incident neutron energies from En = 2.0 MeV down to 0.9 MeV, where the fission characteristics at the vibrational resonance at En = 0.9 MeV were investigated for the first time. The previously reported distinct structure in the angular anisotropy around En = 1.2 and 1.6 MeV wasobserved at En = 0.9 MeV as well. The predicted large changes in fission fragment mass yield and total kinetic energy could not be confirmed. In the resonance the mean total kinetic energy is only about 0.5 MeV higher than at En = 1.8 MeV. At the same time, a slight decrease of the mean heavy fragment mass was observed, probably indicating a slightly increased contribution of the S1 fission mode.
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10.
  • 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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11.
  • 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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12.
  • 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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13.
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14.
  • 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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15.
  • 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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16.
  • 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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17.
  • 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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18.
  • 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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19.
  • 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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20.
  • Jurado, B., et al. (författare)
  • Investigation of the surrogate-reaction method via the simultaneous measurement of gamma-emission and fission probabilities
  • 2017
  • Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. ; 146
  • 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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21.
  • Lebois, M., et al. (författare)
  • Studies for γ-ray emission in the fission process with LICORNE
  • 2016
  • Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. ; 122:01010
  • 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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22.
  • 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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23.
  • Litaize, Olivier, et al. (författare)
  • New results in the modeling of fission and radiative neutron capture with FIFRELIN
  • 2023
  • Ingår i: 15TH INTERNATIONAL CONFERENCE ON NUCLEAR DATA FOR SCIENCE AND TECHNOLOGY, ND2022. - : EDP Sciences.
  • Konferensbidrag (refereegranskat)abstract
    • The FIFRELIN Monte Carlo code has been upgraded recently by adding new capabilities, additional models and updated databases. Several examples are presented in this work as well as three different applications related to the prompt component in fission, gamma cascades from thermal neutron capture and the delayed component in fission associated to the time evolution of decay heat.
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24.
  • Lutter, G., et al. (författare)
  • Radiopurity of a CeBr3 crystal used as scintillation detector
  • 2013
  • 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
  • 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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25.
  • Oberstedt, Andreas, et al. (författare)
  • Characterization of LaCl3:Ce detectors for prompt fission gamma-ray measurements
  • 2009
  • Ingår i: 4th international workshop on nuclear fission and fission-product spectroscopy. - : American Institute of Physics (AIP). - 9780735407145 ; , s. 257-260
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • The properties of cylindrical 1.5//×1.5//LaCl3:Cescintillation detectors were determined. For the energy resolution values between 3.8 and 4.2% at 662 keV were observed, following the expected E-1/2 behavior. The intrinsic full peak efficiency was determined to be more than 50% higher than for NaI:Tl detectors of same size. The observed intrinsic timing resolution for 60Co was estimated to 441 ps and the intrinsic activity of the lanthanum crystals was assessed. © 2009 American Institute of Physics.
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26.
  • Oberstedt, Andreas, et al. (författare)
  • Energy degrader technique for light-charged particle spectroscopy at LOHENGRIN
  • 2008
  • Ingår i: Seminar on Fission VI, Corsendonk Priory, Belgium, September 18-21, 2007. - : WORLD SCIENTIFIC. - 9789812791061 ; , s. 99-106
  • Konferensbidrag (refereegranskat)abstract
    • Although the recoil mass-separator LOHENGRIN at Institute Laue-Langevin was originally designed for the spectrometry of binary fission fragments, it was also used in the past for measuring light-charged particles from ternary fission. However, due to limited electric field settings the energy distribution of the lightest particles was not completely accessible. In this contribution we report on an energy degrader technique that allows the measurement of the entire energy spectra of ternary particles with LOHENGRIN. We demonstrate how the measured particle spectra are distorted by the energy degrader and present results from a Monte Carlo simulation that shows how the original energy distributions are reconstructed. Finally, we apply this procedure to experimental data of ternary particles from the reaction 235U(nth, f).
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27.
  • Oberstedt, Andreas, et al. (författare)
  • Energy degrader technique for light-charged particle spectroscopy at LOHENGRIN
  • 2008
  • Ingår i: ND-2007 International Conference on Nuclear Data for Science and Technology, Nice, France. - Les Ulis, France : EDP Sciences. - 9782759800902 - 9782759800919 ; , s. 379-382
  • Konferensbidrag (refereegranskat)abstract
    • The recoil mass-separator LOHENGRIN at Institute Laue-Langevin was originally designed for the spectrometry of binary fission fragments. Nevertheless, it was also used in the past for measuring light-charged particles from ternary fission. However, due to the electric field settings the energy distribution of the lightest particles was not completely accessible, which made the determination of mean kinetic energies, widths and, hence, emission yields difficult. In this paper we present an energy degrader technique that allows for the measurement of the entire energy spectrum of even the lightest ternary particles with LOHENGRIN.
  •  
28.
  • Oberstedt, Andreas, et al. (författare)
  • Energy degrader technique for light-charged particle spectroscopy at LOHENGRIN
  • 2007
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - Amsterdam : Elsevier. - 0168-9002 .- 1872-9576. ; 570:1, s. 51-54
  • Tidskriftsartikel (refereegranskat)abstract
    • The recoil mass-separator LOHENGRIN at Institute Laue-Langevin was originally designed for the spectrometry of binary fission fragments. Nevertheless, it was also used in the past for measuring light-charged particles from ternary fission. However, due to the electric field settings the energy distribution of the lightest particles was not completely accessible, which made the determination of mean kinetic energies, widths and, hence, emission yields difficult. In this paper we present an energy degrader technique that allows for the measurement of the entire energy spectrum of even the lightest ternary particles with LOHENGRIN.
  •  
29.
  • Oberstedt, Andreas, 1961, et al. (författare)
  • Gamma-ray Measurements with LaBr3: Ce Detectors – thinking Outside the Box
  • 2012
  • Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3884 .- 1875-3892. ; 31, s. 21-28
  • Konferensbidrag (refereegranskat)abstract
    • Recently developed cerium-doped lanthanum bromide (LaBr3: Ce) scintillation detectors have shown to possess promising properties with respect to the detection of γ-rays compared to previously known materials. In this work however, we demonstrate how these detectors may be used to obtain information not only about γ-rays, but also about neutrons, i.e. thinking "inside" and "outside" the box, respectively. For this purpose γ-rays were detected in coincidence with fission fragments and both their energy and their time-of-flight relative to the instant of a fission event is recorded. By evaluating the time-of-flight distributions of γ-rays, identified as decays of excited states after population by inelastically scattered neutrons inside the scintillation crystal as well as other surrounding materials, we show that it is possible to acquire knowledge from and about the spectrum of incident neutrons. We give three examples for conceivable applications, used to determine geometrical profiles, cross sections and neutron spectra, respectively.
  •  
30.
  • Oberstedt, Andreas, et al. (författare)
  • Identification of a Shape Isomer in 235U
  • 2007
  • Ingår i: Physical Review Letters. - : The American Physical Society. - 0031-9007 .- 1079-7114. ; 99:4, s. 1-4
  • Tidskriftsartikel (refereegranskat)abstract
    • The shape isomer in 235U has been searched for in a neutron-induced fission experiment on 234U, which was performed at the isomer spectrometer NEPTUNE of the EC-JRC IRMM. A neutron source, with a tunable pulse frequency in the Hz to kHz range and its individually adjustable neutron pulse width in connection with an appropriate detector system turned out to be the ideal instrument to perform an isomer search, when decay half-lives above 100 us are expected. From the delayed fission events observed for two different NEPTUNE settings and at mean incident neutron energies En = 0.95 and 1.27 MeV the isomeric fission half-life could be determined to be T_1/2 = (3.6 ± 1.8) ms. The corresponding cross section was determined to sigma_if = (10 ± 8) ub. With these results an experimental confirmation for the existence of a superdeformed shape isomer in odd-uranium isotopes is given for the first time.
  •  
31.
  • Oberstedt, Andreas, 1960-, et al. (författare)
  • Identification of prompt fission gamma-rays with lanthanum-chloride scintillation detectors
  • 2012
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576. ; 668, s. 14-20
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper we demonstrate the employment of LaCl3 : Ce scintillation detectors for the identification of prompt fission gamma-rays from gamma-radiation in contrast to other reactions. We present the properties of cylindrical 1.5 in. x 1.5 in. detectors in terms of intrinsic activity, energy resolution, intrinsic full peak efficiency and intrinsic timing resolution. In addition, we show results from the measurement of gamma-rays emitted in coincidence with the spontaneous fission of Cf-252, which lead us to the conclusion that the properties of the detectors used in this work, in particular the good timing resolution and a reasonably good energy resolution, are more than just sufficient for the assessment of prompt gamma-heat in future nuclear reactors as requested by the OECD. Hence, in our opinion, LaCl3 : Ce detectors, compared to those made out of LaBr3 : Ce crystals, represent an appropriate and quasi low-cost choice for the above mentioned applications.
  •  
32.
  • Oberstedt, Andreas, 1961, et al. (författare)
  • Identification of prompt fission γ-rays with lanthanum-chloride scintillation detectors
  • 2012
  • Ingår i: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002. ; 668:0, s. 14--20-20
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper we demonstrate the employment of LaCl3:Ce scintillation detectors for the identification of prompt fission γ-rays from γ-radiation in contrast to other reactions. We present the properties of cylindrical 1.5 in.×1.5 in. detectors in terms of intrinsic activity, energy resolution, intrinsic full peak efficiency and intrinsic timing resolution. In addition, we show results from the measurement of γ-rays emitted in coincidence with the spontaneous fission of 252Cf, which lead us to the conclusion that the properties of the detectors used in this work, in particular the good timing resolution and a reasonably good energy resolution, are more than just sufficient for the assessment of prompt γ-heat in future nuclear reactors as requested by the OECD. Hence, in our opinion, LaCl3:Ce detectors, compared to those made out of LaBr3:Ce crystals, represent an appropriate and quasi low-cost choice for the above mentioned applications.
  •  
33.
  • Oberstedt, Andreas, 1961, et al. (författare)
  • Impact of low-energy photons on the characteristics of prompt fission gamma-ray spectra
  • 2015
  • Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 92:1
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper we report on a new study of prompt gamma-rays from the spontaneous fission of Cf-252. Photons were measured in coincidence with fission fragments by employing four different lanthanide halide scintillation detectors. Together with results from a previous work of ours, we determined characteristic parameters with high precision, such as the average gamma-ray multiplicity (nu) over bar (gamma) = (8.29 +/- 0.13), the average energy per photon is an element of(gamma) = (0.80 +/- 0.02) MeV, and the total gamma-ray energy release per fission E-gamma,(tot) = (6.65 +/- 0.10) MeV. The excellent agreement between the individual results obtained in all six measurements proves the good repeatability of the applied experimental technique. The impact of low-energy photons, i.e., below 500 keV, on prompt fission gamma-ray spectra characteristics has been investigated as well by comparing our results with those taken with the DANCE detector system, which appears to suffer from absorption effects in the low-energy region. Correction factors for this effect were estimated, giving results comparable to ours as well as to historical ones. From this we demonstrate that the different techniques of determining the average gamma-ray multiplicity, either from a properly measured and normalized spectrum or a measured multiplicity distribution, give equivalent and consistent results.
  •  
34.
  • 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.
  •  
35.
  • Oberstedt, Andreas, et al. (författare)
  • Neutron measurements with lanthanum-bromide scintillation detectors : a first approach
  • 2013
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 708, s. 7-14
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper we report on the measurement of gamma-rays using a 2 in. x 2 in. LaBr3:Ce scintillation detector. The gamma-rays were emitted in the spontaneous fission of Cf-252 and detected in coincidence with fission fragments. After presenting some of the properties of the detector, we show how well gamma-rays produced in different reactions may easily be distinguished by their characteristic time-of-flight. Then we focus on the analysis of gamma-rays from inelastically scattered neutrons in the scintillation crystal and demonstrate how this information may be used for neutron spectroscopy. We determine the neutron detection efficiency and compare it to the result of calculations based on existing reaction cross-sections. Finally, we discuss the detection performance in relation to other detector systems commonly used for neutron monitoring.
  •  
36.
  •  
37.
  • Oberstedt, Andreas, 1960-, et al. (författare)
  • New prompt fission gamma-ray spectral data and its implication on present evaluated nuclear data files
  • 2013
  • Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3892 .- 1875-3884. ; 47, s. 156-165
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper we report on new spectral prompt gamma-ray measurements from the spontaneous fission of Cf-252 and thermal neutron-induced fission of U-236*. In both experiments, fission of U-236*. In both experiments, gamma-ray multiplicities, average and total gamma-energies were extracted. gamma-ray multiplicities, average and total.-energies were extracted. Apart from one recent measurement on Cf-252, about four decades have passed since the last dedicated experiments were reported in literature. Hence, there was a need for a revision, not only with respect to high priority nuclear data requests by the Nuclear Energy Agency (NEA). In the first mentioned experiment we have measured prompt fission gamma-rays with both cerium-doped LaBr3 and CeBr3 scintillation detectors, which both exhibit excellent timing and good energy resolution. The results from both detectors are in excellent agreement with each other and confirm the historical data. In the experiment on U-235(n(th), f) we employed cerium-doped LaCl3 detectors, together with the lanthanum bromide detectors mentioned above. Even here the first results indicate a good agreement with data from the early 1970' s. They are also in accordance with data in evaluated libraries like ENDF/B-VII.0, while this is not the case for Cf-252(SF). Hence, here an update is strongly recommended.
  •  
38.
  • Oberstedt, Andreas, 1961, et al. (författare)
  • Prompt fission gamma-ray spectra characteristics - systematics and predictions
  • 2015
  • Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3884 .- 1875-3892. ; 64, s. 91-100
  • Konferensbidrag (refereegranskat)abstract
    • Revised systematics for prompt fission gamma-ray spectra (PFGS) characteristics as function of both atomic and mass number of the compound system, derived from recent experiments on thermal-neutron induced and spontaneous fission, is presented and applied to fission induced by fast neutrons. Results from these calculations for U-238(n, f) and U-235(n, f) for incident neutron energies from 0 to 20 MeV are compared to new experimental results, exhibiting nice agreement. Very recent PFGS measurements for Pu-240(sf) and Pu-242(sf) have been evaluated and the determined PFGS characteristics are shown to also fit well with the systematics. From this we conclude that the obtained systematics, although purely empirical, is indeed a useful tool for the prediction of average total gamma-ray energy released in prompt fission, mean energy per photon as well as average photon multiplicity for fissioning systems, which are difficult or even impossible to study experimentally. (C) 2015 The Authors. Published by Elsevier B.V.
  •  
39.
  • Oberstedt, Andreas, et al. (författare)
  • Recent results on the neutron-induced fission cross-section of 231Pa
  • 2005
  • Ingår i: Proceedings of the 3rd international workshop on nuclear fission and fission-product spectroscopy. - : American Institute of Physics. - 0735402884 ; , s. 27-30
  • Konferensbidrag (refereegranskat)abstract
    • The cross-section for the neutron-induced fission of 231Pa has recently been measured from the threshold to En = 3.5 MeV. The experimental results are described in terms of extended statistical model calculations.
  •  
40.
  • Oberstedt, Andreas, 1961, et al. (författare)
  • Systematics of prompt fission γ-ray spectra characteristics
  • 2014
  • Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3884 .- 1875-3892. ; 59:C, s. 24-30
  • Konferensbidrag (refereegranskat)abstract
    • Systematics from 2001, describing prompt fission γ-ray spectra (PFGS) characteristics as function of mass and atomic number of the fissioning system, has been revisited and parameters have been revised, based on recent experimental results. Although originally expressed for spontaneous and thermal neutron induced fission, validity for fast neutrons was assumed and applied to predict PFGS characteristics for the reaction n + 238U up to incident neutron energies of En = 20 MeV. The results from this work are compared with preliminary experimental results.
  •  
41.
  • Oberstedt, S., et al. (författare)
  • Artificial diamonds as radiation-hard detectors for ultra-fast fission-fragment timing
  • 2013
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 714, s. 31-37
  • Tidskriftsartikel (refereegranskat)abstract
    • In the framework of the construction of the double time-of-flight spectrometer VERDI, where we aim at measuring pre- and post-neutron masses directly and simultaneously, ultra-fast time pick-up detectors based on artificial diamond material were investigated for the first time with fission fragments from Cf-252 (0.5 MeV/u < E/A < 2 MeV/u). Signal stability under a high radiation fluence was determined up to at least 10(9) fission-fragments/cm(2) together with more than 3.5 x 10(9) neutrons/cm(2) and 3 x 10(10) alpha-particles/cm(2). This fluence is characteristic for fission experiments. The pre-requisite for the observed signal stability is the application of priming of the diamond material with a strong beta-source for about 48 h. The intrinsic timing resolution of a 100 mu m thick polycrystalline CVD diamond detector with a size of 1 x 1 cm(2) was determined to sigma(int) = (283 +/- 41) ps by comparison with Monte-Carlo simulations. Using broadband pre-amplifiers, 4-fold segmented detectors of same total size and with a thickness of 180 mu m show an intrinsic timing resolution of sigma(int) = (106 +/- 21) ps. This is highly competitive with the best micro-channel plate detectors. Due to the limited and batch-dependent charge collection efficiency of poly-crystalline diamond material, the detection efficiency for fission fragments may be smaller than 100%.
  •  
42.
  • 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. 
  •  
43.
  • Oberstedt, S., et al. (författare)
  • Future research program on prompt gamma-ray emission in nuclear fission
  • 2015
  • Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-601X .- 1434-6001. ; 51:12, s. 1-9
  • Forskningsöversikt (refereegranskat)abstract
    • In recent years the measurement of prompt fission gamma-ray spectra (PFGS) has gained renewed interest, after about forty years since the first comprehensive studies of the reactions U-235(n(th), f), Pu-239(n(th), f) and Cf-252(sf). The renaissance was initiated by requests for new values especially for.-ray multiplicity and average total energy release per fission in neutron-induced fission of U-235 and Pu-239. Both isotopes are considered the most important ones with respect to the modeling of innovative cores required for the Generation-IV reactors, the majority working with fast neutrons. During the last 5 years we have conducted a systematic study of spectral data for thermal-neutron-induced fission on U-235 and Pu-241 as well as for the spontaneous fission of Cf-252 with unprecedented accuracy. From the new data we conclude that those reactions do not considerably contribute to the observed heat excess and suspect other reactions playing a significant role. Possible contributions may originate from fast-neutron-induced reactions on U-238, which is largely present in the fuel, or from gamma-induced fission from neutron capture in the construction material. A first experiment campaign on prompt gamma-ray emission from fast-neutron-induced fission on U-235,U-238 was successfully performed in order to test our assumptions. In the following we attempt to summarize, what has been done in the field to date, and to motivate future measurement campaigns exploiting dedicated neutron and photon beams as well as upcoming highly efficient detector assemblies.
  •  
44.
  • 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.
  •  
45.
  • Oberstedt, Stephan, et al. (författare)
  • Light charged particle emission in the reaction 251Cf(nth, f)
  • 2005
  • Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474 .- 1873-1554. ; 761:3-4, s. 173-189
  • Tidskriftsartikel (refereegranskat)abstract
    • High resolution measurements of light charged particles (LCP) emitted in thermal neutron-induced fission of 252Cf ∗ (E=6.2 MeV) have been performed with the recoil mass-separator LOHENGRIN. For this compound nuclear system emission yields of LCPs, their mean kinetic energies and widths have been obtained for 8 isotopes with nuclear charges Z⩾2. For 13 further isotopes the emission yields were estimated on the basis of systematics on their kinetic energy distributions. 34Al and 36Si emission has been observed for the first time in thermal neutron-induced fission.
  •  
46.
  •  
47.
  • Oberstedt, Stephan, et al. (författare)
  • Neutron-induced fission cross-section of 231Pa
  • 2006
  • Ingår i: Proceedings of NEMEA-2 Workshop on Neutron Measurements, Evaluations and Applications - 2, October 20-23, 2004, Bucharest, Rumania, EUR Report 22136 EN.
  • Konferensbidrag (refereegranskat)
  •  
48.
  • 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).
  •  
49.
  •  
50.
  • 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.
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