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Oberstedt, Andreas
Publications (10 of 36) Show all publications
Hambsch, F.-J. -., Oberstedt, S., Al-Adili, A., Brys, T., Billnert, R., Matei, C., . . . Vidali, M. (2014). Fission Fragment Yield, Cross Section and Prompt Neutron and Gamma Emission Data from Actinide Isotopes. Nuclear Data Sheets, 119, E38-E41
Open this publication in new window or tab >>Fission Fragment Yield, Cross Section and Prompt Neutron and Gamma Emission Data from Actinide Isotopes
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2014 (English)In: Nuclear Data Sheets, ISSN 0090-3752, E-ISSN 1095-9904, Vol. 119, p. E38-E41Article in journal (Refereed) Published
Abstract [en]

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.

National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:oru:diva-43241 (URN)10.1016/j.nds.2014.08.012 (DOI)000347706200128 ()
Available from: 2015-03-03 Created: 2015-03-03 Last updated: 2019-03-05Bibliographically approved
Oberstedt, S., Billnert, R., Belgya, T., Borcea, R., Brys, T., Geerts, W., . . . Vidali, M. (2014). New Prompt Fission gamma-ray Data in Response to the OECD/NEA High Priority Request. Nuclear Data Sheets, 119, E225-E228
Open this publication in new window or tab >>New Prompt Fission gamma-ray Data in Response to the OECD/NEA High Priority Request
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2014 (English)In: Nuclear Data Sheets, ISSN 0090-3752, E-ISSN 1095-9904, Vol. 119, p. E225-E228Article in journal (Refereed) Published
Abstract [en]

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).

National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:oru:diva-43243 (URN)10.1016/j.nds.2014.08.062 (DOI)000347706200178 ()
Note

Funding Agencies:

European Commission in the framework of the EFNUDAT 31027

European Commission in the framework of the ERINDA programme 269499

Available from: 2015-03-03 Created: 2015-03-03 Last updated: 2019-03-05Bibliographically approved
Ledoux, X., Aiche, M., Avrigeanu, M., Avrigeanu, V., Audouin, L., Oberstedt, A., . . . Varignon, C. (2014). The Neutrons for Science Facility at SPIRAL-2. Nuclear Data Sheets, 119, E353-E356
Open this publication in new window or tab >>The Neutrons for Science Facility at SPIRAL-2
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2014 (English)In: Nuclear Data Sheets, ISSN 0090-3752, E-ISSN 1095-9904, Vol. 119, p. E353-E356Article in journal (Refereed) Published
Abstract [en]

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.

National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:oru:diva-43242 (URN)10.1016/j.nds.2014.08.097 (DOI)000347706200213 ()
Available from: 2015-03-03 Created: 2015-03-03 Last updated: 2019-03-05Bibliographically approved
Oberstedt, S., Borcea, R., Brys, T., Gamboni, T., Geerts, W., Hambsch, F.-J. -., . . . Vidali, M. (2013). Artificial diamonds as radiation-hard detectors for ultra-fast fission-fragment timing. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 714, 31-37
Open this publication in new window or tab >>Artificial diamonds as radiation-hard detectors for ultra-fast fission-fragment timing
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2013 (English)In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 714, p. 31-37Article in journal (Refereed) Published
Abstract [en]

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%.

Keywords
Fission fragment spectroscopy, Timing resolution, Artificial diamond, Chemical vapor deposited diamond, Time of flight
National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:oru:diva-29961 (URN)10.1016/j.nima.2013.02.029 (DOI)000319251800006 ()
Available from: 2013-07-05 Created: 2013-07-05 Last updated: 2017-12-06Bibliographically approved
Oberstedt, A., Belgya, T., Billnert, R., Borcea, R., Brys, T., Geerts, W., . . . Vidali, M. (2013). Improved values for the characteristics of prompt-fission gamma-ray spectra from the reaction U-235(n(th), f). Physical Review C. Nuclear Physics, 87(5), 051602
Open this publication in new window or tab >>Improved values for the characteristics of prompt-fission gamma-ray spectra from the reaction U-235(n(th), f)
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2013 (English)In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 87, no 5, p. 051602-Article in journal (Refereed) Published
Abstract [en]

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.

National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:oru:diva-29964 (URN)10.1103/PhysRevC.87.051602 (DOI)000319283100001 ()
Available from: 2013-07-05 Created: 2013-07-05 Last updated: 2017-12-06Bibliographically approved
Oberstedt, A., Billnert, R. & Oberstedt, S. (2013). Neutron measurements with lanthanum-bromide scintillation detectors: a first approach. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 708, 7-14
Open this publication in new window or tab >>Neutron measurements with lanthanum-bromide scintillation detectors: a first approach
2013 (English)In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 708, p. 7-14Article in journal (Refereed) Published
Abstract [en]

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.

Keywords
Neutron measurements, Lanthanum bromide, Scintillation detector, Cf-252(sf), Br-79(n, n '), Br-81(n, n ')
National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:oru:diva-28779 (URN)10.1016/j.nima.2013.01.005 (DOI)000316192300002 ()
Available from: 2013-04-24 Created: 2013-04-24 Last updated: 2017-12-06Bibliographically approved
Oberstedt, A., Belgya, T., Billnert, R., Hambsch, F.-J. -., Kis, Z., Perez, T. M., . . . Vidali, M. (2013). New prompt fission gamma-ray spectral data and its implication on present evaluated nuclear data files. Paper presented at Scientific Workshop on Nuclear Fission Dynamics and the Emission of Prompt Neutrons and Gamma Rays, NOV 28-30, 2012, Biarritz, FRANCE. Physics Procedia, 47, 156-165
Open this publication in new window or tab >>New prompt fission gamma-ray spectral data and its implication on present evaluated nuclear data files
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2013 (English)In: Physics Procedia, ISSN 1875-3892, E-ISSN 1875-3892, Vol. 47, p. 156-165Article in journal (Refereed) Published
Abstract [en]

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.

Keywords
Prompt fission gamma-rays, total gamma-ray energy, prompt gamma-ray multiplicity, Generation IV, nuclear energy, lanthanum bromide, cerium bromide, lanthanum chloride, scintillation detector, Cf-252(SF), U-235(n(th, )f)
National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:oru:diva-40190 (URN)10.1016/j.phpro.2013.06.023 (DOI)000345234700022 ()2-s2.0-84902241246 (Scopus ID)
Conference
Scientific Workshop on Nuclear Fission Dynamics and the Emission of Prompt Neutrons and Gamma Rays, NOV 28-30, 2012, Biarritz, FRANCE
Available from: 2015-01-07 Created: 2015-01-07 Last updated: 2018-05-22Bibliographically approved
Göök, A., Hambsch, F.-J. -., Oberstedt, A. & Oberstedt, S. (2012). Application of the Shockley-Ramo theorem on the grid inefficiency of Frisch grid ionization chambers. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 664(1), 289-293
Open this publication in new window or tab >>Application of the Shockley-Ramo theorem on the grid inefficiency of Frisch grid ionization chambers
2012 (English)In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 664, no 1, p. 289-293Article in journal (Refereed) Published
Abstract [en]

The concept of grid inefficiency in Frisch grid ionization chambers and its influence on the anode pulse shape is explained in terms of the Shockley-Ramo 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.

Place, publisher, year, edition, pages
Elsevier, 2012
Keywords
Frisch grid, Ionization chamber, Grid inefficiency, Shockley-Ramo theorem
National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:oru:diva-21937 (URN)10.1016/j.nima.2011.10.052 (DOI)000299592000038 ()2-s2.0-84555189633 (Scopus ID)
Available from: 2012-03-05 Created: 2012-03-05 Last updated: 2017-12-07Bibliographically approved
Oberstedt, S., Oberstedt, A., Birgersson, E., Fabry, I., Hambsch, F. J., Kornilov, N., . . . Tudora, A. (2012). First results on the neutron-induced fission cross-section of Pa-231 for incident neutron energies E-n > 17 MeV. Annals of Nuclear Energy, 43, 26-30
Open this publication in new window or tab >>First results on the neutron-induced fission cross-section of Pa-231 for incident neutron energies E-n > 17 MeV
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2012 (English)In: Annals of Nuclear Energy, ISSN 0306-4549, E-ISSN 1873-2100, Vol. 43, p. 26-30Article in journal (Refereed) Published
Abstract [en]

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. 

Place, publisher, year, edition, pages
Elsevier, 2012
Keywords
Protactinium-231, Neutron-induced fission cross-section, Third chance fission of Pa-231, E-n > 17 MeV
National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:oru:diva-22712 (URN)10.1016/j.anucene.2011.12.023 (DOI)000302426000005 ()2-s2.0-84855910119 (Scopus ID)
Available from: 2012-05-03 Created: 2012-05-03 Last updated: 2018-05-08Bibliographically approved
Oberstedt, A., Oberstedt, S., Billnert, R., Geerts, W., Hambsch, F.-J. -. & Karlsson, J. (2012). Identification of prompt fission gamma-rays with lanthanum-chloride scintillation detectors. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 668, 14-20
Open this publication in new window or tab >>Identification of prompt fission gamma-rays with lanthanum-chloride scintillation detectors
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2012 (English)In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 668, p. 14-20Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
Elsevier, 2012
Keywords
Prompt fission gamma-rays, Lanthanum chloride, Scintillation detector, Energy resolution, Timing resolution, Cf-252(sf)
National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:oru:diva-22247 (URN)10.1016/j.nima.2011.11.088 (DOI)000300864200003 ()2-s2.0-83755164229 (Scopus ID)
Available from: 2012-03-26 Created: 2012-03-26 Last updated: 2017-12-07Bibliographically approved
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