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Österlund, Michael
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Publications (10 of 78) Show all publications
Rakopoulos, V., Lantz, M., Pomp, S., Solders, A., Al-Adili, A., Canete, L., . . . Penttilä, H. (2019). Isomeric fission yield ratios for odd-mass Cd and In isotopes using the phase-imaging ion-cyclotron-resonance technique. Physical Review C, 99(1), Article ID 014617.
Open this publication in new window or tab >>Isomeric fission yield ratios for odd-mass Cd and In isotopes using the phase-imaging ion-cyclotron-resonance technique
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2019 (English)In: Physical Review C, ISSN 2469-9985, Vol. 99, no 1, article id 014617Article in journal (Refereed) Published
Abstract [en]

Isomeric yield ratios for the odd-A isotopes of Cd119-127 and In119-127 from 25-MeV proton-induced fission on natural uranium have been measured at the JYFLTRAP double Penning trap, by employing the phase-imaging ion-cyclotron-resonance technique. With the significantly improved mass resolution of this novel method isomeric states separated by 140 keV from the ground state, and with half-lives of the order of 500 ms, could be resolved. This opens the door for obtaining new information on low-lying isomers, which are important for nuclear structure, fission, and astrophysics. In the present work the experimental isomeric yield ratios are used for the estimation of the root-mean-square angular momentum J(rms) of the primary fragments. The results show a dependency on the number of unpaired protons and neutrons, where the odd-Z In isotopes carry larger angular momenta. The deduced values of J(rms) display a linear relationship when compared with the electric quadrupole moments of the fission products.

National Category
Subatomic Physics
Research subject
Physics with specialization in Nuclear Physics
Identifiers
urn:nbn:se:uu:diva-364949 (URN)10.1103/PhysRevC.99.014617 (DOI)000456288000005 ()
Funder
EU, FP7, Seventh Framework Programme, 605203Swedish Radiation Safety AuthoritySwedish Nuclear Fuel and Waste Management Company, SKB
Available from: 2018-11-06 Created: 2018-11-06 Last updated: 2019-02-11Bibliographically approved
Pomp, S. (2019). Isomeric yield ratio measurements at IGISOL/JYFLTRAP for assessing angular momenta of fission fragments: Invited talk, NUSTAR seminar series, GSI.
Open this publication in new window or tab >>Isomeric yield ratio measurements at IGISOL/JYFLTRAP for assessing angular momenta of fission fragments: Invited talk, NUSTAR seminar series, GSI
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2019 (English)Other (Other academic)
National Category
Subatomic Physics
Research subject
Physics with specialization in Applied Nuclear Physics
Identifiers
urn:nbn:se:uu:diva-396855 (URN)
Available from: 2019-11-11 Created: 2019-11-11 Last updated: 2019-11-11
Al-Adili, A., Jansson, K., Tarrio, D., Hambsch, F.-J., Gook, A., Oberstedt, S., . . . Pomp, S. (2018). Studying fission neutrons with 2E-2v and 2E. In: Hambsch, FJ Carjan, N Rusko, I (Ed.), SCIENTIFIC WORKSHOP ON NUCLEAR FISSION DYNAMICS AND THE EMISSION OF PROMPT NEUTRONS AND GAMMA RAYS (THEORY-4): . Paper presented at 4th Scientific Workshop on Nuclear Fission Dynamics and the Emission of Prompt Neutrons and Gamma Rays (Theory), JUN 20-22, 2017, Varna, BULGARIA. , Article ID UNSP 00002.
Open this publication in new window or tab >>Studying fission neutrons with 2E-2v and 2E
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2018 (English)In: SCIENTIFIC WORKSHOP ON NUCLEAR FISSION DYNAMICS AND THE EMISSION OF PROMPT NEUTRONS AND GAMMA RAYS (THEORY-4) / [ed] Hambsch, FJ Carjan, N Rusko, I, 2018, article id UNSP 00002Conference paper, Published paper (Refereed)
Abstract [en]

This work aims at measuring prompt-fission neutrons at different excitation energies of the nucleus. Two independent techniques, the 2E-2v and the 2E techniques, are used to map the characteristics of the mass-dependent prompt fission neutron multiplicity, 7(A), when the excitation energy is increased. The VERDI 2E-2v spectrometer is being developed at JRC-GEEL. The Fission Fragment (FF) energies are measured using two arrays of 16 silicon (Si) detectors each. The FFs velocities are obtained by time-of-flight, measured between micro-channel plates (MCP) and Si detectors. With MCPs placed on both sides of the fission source, VERDI allows for independent timing measurements for both fragments. Cf-252(sf) was measured and the present results revealed particular features of the 2E-2v technique. Dedicated simulations were also performed using the GEF code to study important aspects of the 2E-2v technique. Our simulations show that prompt neutron emission has a non-negligible impact on the deduced fragment data and affects also the shape of 17(A). Geometrical constraints lead to a total-kinetic energy-dependent detection efficiency. The 2E technique utilizes an ionization chamber together with two liquid scintillator detectors. Two measurements have been performed, one of Cf-252(sf) and another one of thermal-neutron induced fission in U-235(n,f). Results from Cf-252(sf) are reported here.

Series
EPJ Web of Conferences, ISSN 2100-014X ; 169
National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-361440 (URN)10.1051/epjconf/201816900002 (DOI)000433153800001 ()978-2-7598-9031-6 (ISBN)
Conference
4th Scientific Workshop on Nuclear Fission Dynamics and the Emission of Prompt Neutrons and Gamma Rays (Theory), JUN 20-22, 2017, Varna, BULGARIA
Available from: 2018-12-10 Created: 2018-12-10 Last updated: 2019-02-28Bibliographically approved
Al-Adili, A., Tarrío, D., Hambsch, F.-J., Göök, A., Jansson, K., Solders, A., . . . Pomp, S. (2017). Neutron-multiplicity experiments for enhanced fission modelling. In: Plompen, A.; Hambsch, FJ.; Schillebeeckx, P.; Mondelaers, W.; Heyse, J.; Kopecky, S.; Siegler, P.; Oberstedt, S. (Ed.), EPJ Web of Conferences: . Paper presented at ND 2016: International Conference on Nuclear Data for Science and Technology, September 11-16, 2016, Bruges, Belgium.. , 146, Article ID 04056.
Open this publication in new window or tab >>Neutron-multiplicity experiments for enhanced fission modelling
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2017 (English)In: EPJ Web of Conferences / [ed] Plompen, A.; Hambsch, FJ.; Schillebeeckx, P.; Mondelaers, W.; Heyse, J.; Kopecky, S.; Siegler, P.; Oberstedt, S., 2017, Vol. 146, article id 04056Conference paper, Published paper (Refereed)
Abstract [en]

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.

Series
EPJ Web of Conferences, ISSN 2100-014X
National Category
Subatomic Physics
Research subject
Applied Nuclear Physics
Identifiers
urn:nbn:se:uu:diva-339390 (URN)10.1051/epjconf/201714604056 (DOI)000426429500155 ()978-2-7598-9020-0 (ISBN)
Conference
ND 2016: International Conference on Nuclear Data for Science and Technology, September 11-16, 2016, Bruges, Belgium.
Funder
Swedish Radiation Safety Authority
Available from: 2018-01-18 Created: 2018-01-18 Last updated: 2019-02-28Bibliographically approved
Al-Adili, A., Tarrío, D., Hambsch, F.-J. -., Gook, A., Jansson, K., Solders, A., . . . Pomp, S. (2016). Analysis of prompt fission neutrons in U-235(nth,f) and fission fragment distributions for the thermal neutron induced fission of U-234. In: CNR*15 - 5th International Workshop On Compound-Nuclear Reactions And Related Topics: . Paper presented at 5th International Workshop on Compound-Nuclear Reactions and Related Topics (CNR), OCT 19-23, 2015, Tokyo, JAPAN. , Article ID 01007.
Open this publication in new window or tab >>Analysis of prompt fission neutrons in U-235(nth,f) and fission fragment distributions for the thermal neutron induced fission of U-234
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2016 (English)In: CNR*15 - 5th International Workshop On Compound-Nuclear Reactions And Related Topics, 2016, article id 01007Conference paper, Published paper (Refereed)
Abstract [en]

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.

Series
EPJ Web of Conferences, ISSN 2100-014X ; 122
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-314830 (URN)10.1051/epjconf/201612201007 (DOI)000389877200007 ()
Conference
5th International Workshop on Compound-Nuclear Reactions and Related Topics (CNR), OCT 19-23, 2015, Tokyo, JAPAN
Available from: 2017-02-07 Created: 2017-02-06 Last updated: 2019-02-28Bibliographically approved
Alhassan, E., Sjöstrand, H., Helgesson, P., Österlund, M., Pomp, S., Koning, A. J. & Rochman, D. (2016). On the use of integral experiments for uncertainty reduction of reactor macroscopic parameters within the TMC methodology. Progress in nuclear energy (New series), 88, 43-52
Open this publication in new window or tab >>On the use of integral experiments for uncertainty reduction of reactor macroscopic parameters within the TMC methodology
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2016 (English)In: Progress in nuclear energy (New series), ISSN 0149-1970, E-ISSN 1878-4224, Vol. 88, p. 43-52Article in journal (Refereed) Published
Abstract [en]

The current nuclear data uncertainties observed in reactor safety parameters for some nuclides call for safety concerns especially with respect to the design of GEN-IV reactors and must therefore be reduced significantly. In this work, uncertainty reduction using criticality benchmark experiments within the Total Monte Carlo methodology is presented. Random nuclear data libraries generated are processed and used to analyze a set of criticality benchmarks. Since the calculated results for each random nuclear data used are different, an algorithm was used to select (or assign weights to) the libraries which give a good description of experimental data for the analyses of the benchmarks. The selected or weighted libraries were then used to analyze the ELECTRA reactor. By using random nuclear data libraries constrained with only differential experimental data as our prior, the uncertainties observed were further reduced by constraining the files with integral experimental data to obtain a posteriori uncertainties on the k(eff). Two approaches are presented and compared: a binary accept/reject and a method of assigning file weights based on the likelihood function. Significant reductions in (PU)-P-239 and Pb-208 nuclear data uncertainties in the k(eff) were observed after implementing the two methods with some criticality benchmarks for the ELELIRA reactor. (C) 2015 Elsevier Ltd. All rights reserved.

Keywords
Nuclear data, uncertainty reduction, binary accept/reject, file weights, Total Monte Carlo, criticality benchmarks, ELECTRA
National Category
Subatomic Physics
Research subject
Physics with specialization in Applied Nuclear Physics
Identifiers
urn:nbn:se:uu:diva-264410 (URN)10.1016/j.pnucene.2015.11.015 (DOI)000372564400006 ()
Funder
Swedish Research Council
Available from: 2015-10-11 Created: 2015-10-11 Last updated: 2017-12-01Bibliographically approved
Alhassan, E., Sjöstrand, H., Helgesson, P., Österlund, M., Pomp, S., Arjan, J. K. & Rochman, D. (2016). Selecting benchmarks for reactor simulations: an application to a Lead Fast Reactor. Annals of Nuclear Energy, 96, 158-169
Open this publication in new window or tab >>Selecting benchmarks for reactor simulations: an application to a Lead Fast Reactor
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2016 (English)In: Annals of Nuclear Energy, ISSN 0306-4549, E-ISSN 1873-2100, Vol. 96, p. 158-169Article in journal (Refereed) Published
Abstract [en]

For several decades reactor design has been supported by computer codes for the investigation of reactor behavior under both steady state and transient conditions. The use of computer codes to simulate reactor behavior enables the investigation of various safety scenarios saving time and cost. There has been an increase in the development of in-house (local) codes by various research groups in recent times for preliminary design of specific or targeted nuclear reactor applications. These codes must be validated and calibrated against experimental benchmark data with their evolution and improvements. Given the large number of benchmarks available, selecting these benchmarks for reactor calculations and validation of simulation codes for specific or target applications can be rather tedious and difficult. In the past, the traditional approach based on expert judgement using information provided in various handbooks, has been used for the selection of these benchmarks. This approach has been criticized because it introduces a user bias into the selection process. This paper presents a method for selecting these benchmarks for reactor calculations for specific reactor applications based on the Total Monte Carlo (TMC) method. First, nuclear model parameters are randomly sampled within a given probability distribution and a large set of random nuclear data files are produced using the TALYS code system. These files are processed and used to analyze a target reactor system and a set of criticality benchmarks. Similarity between the target reactor system and one or several benchmarks is quantified using a similarity index. The method has been applied to the European Lead Cooled Reactor (ELECTRA) and a set of plutonium and lead sensitive criticality benchmarks using the effective multiplication factor (keffkeff). From the study, strong similarity were observed in the keffkeff between ELECTRA and some plutonium and lead sensitive criticality benchmarks. Also, for validation purposes, simulation results for a list of selected criticality benchmarks simulated with the MCNPX and SERPENT codes using different nuclear data libraries have been compared with experimentally measured benchmark keff values.

Keywords
Benchmark selection; Criticality benchmarks; Random nuclear data; Total Monte Carlo (TMC); Code validation
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-264414 (URN)10.1016/j.anucene.2016.05.033 (DOI)000380600300017 ()
External cooperation:
Funder
Swedish Research Council
Available from: 2015-10-11 Created: 2015-10-11 Last updated: 2017-12-01Bibliographically approved
Alhassan, E., Sjöstrand, H., Duan, J., Gustavsson, C., Pomp, S., Österlund, M., . . . Koning, A. J. (2016). Uncertainty analysis of Lead cross sections on reactor safety for ELECTRA. In: SNA + MC 2013 - Joint International Conference on Supercomputing in Nuclear Applications + Monte Carlo: . Paper presented at Joint International Conference on Supercomputing in Nuclear Applications + Monte Carlo (SNA & MC 2013); 27-31 October 2013; Paris, France. , Article ID 02401.
Open this publication in new window or tab >>Uncertainty analysis of Lead cross sections on reactor safety for ELECTRA
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2016 (English)In: SNA + MC 2013 - Joint International Conference on Supercomputing in Nuclear Applications + Monte Carlo, 2016, article id 02401Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

The Total Monte Carlo (TMC) method was used in this study to assess the impact of Pb-206, 207 and 208 nucleardata uncertainties on k-eff , beta-eff, coolant temperature coefficient, the coolant void worth for the ELECTRA reactor. Relatively large uncertainties were observed in the k-eff and the coolant void worth for all the isotopes with significant contribution coming from Pb-208 nuclear data. The large Pb-208 nuclear data uncertainty observed was further investigated by studying the impact of partial channels on the k-eff and beta-eff. Various sections of ENDF file: elasticscattering (n,el), inelastic scattering (n,inl), neutron capture (n,gamma), (n,2n), resonance parameters and the angular distribution were varied randomly and distributions in k-eff and beta-eff obtained. The dominant contributions to the uncertainty in the k-eff from Pb-208 came from uncertainties in the resonance parameters; however, elastic scattering cross section and the angular distribution also had significant impact. The impact of nuclear data uncertainties on the beta-eff was observed to be small.

Keywords
TMC, nuclear data uncertainty, lead isotopes, safety parameters, ELECTRA, fuel cycle
National Category
Other Physics Topics
Research subject
Applied Nuclear Physics
Identifiers
urn:nbn:se:uu:diva-208843 (URN)10.1051/snamc/201402401 (DOI)000408930200075 ()
Conference
Joint International Conference on Supercomputing in Nuclear Applications + Monte Carlo (SNA & MC 2013); 27-31 October 2013; Paris, France
Projects
GENIUS project
Available from: 2013-10-09 Created: 2013-10-09 Last updated: 2019-02-28Bibliographically approved
Jansson, P., Österlund, M., Jacobsson Svärd, S. & Grape, S. (2015). A platform for feed-forward and follow-up of students' progression in oral presentation within a study programme. In: : . Paper presented at 5:e Utvecklingskonferensen för Sveriges ingenjörsutbildningar.
Open this publication in new window or tab >>A platform for feed-forward and follow-up of students' progression in oral presentation within a study programme
2015 (English)Conference paper, Oral presentation with published abstract (Other academic)
Abstract [en]

Didactic research has shown that feedforward has a positive effect on students' experience of their progression in oral presentation. However, studies also show that students often experience a lack of feedback from teachers and audience attending their presentations and consequently they lack an experience of progression.

In this work we present a platform for structured documentation and follow-up of students' progress of skills in oral presentation that has been been implemented within the bachelor programme in nuclear engineering at Uppsala University. The platform provides efficient communication of feedback and feedforward to the students over this one-year programme, involving several courses and teachers.

The platform is implemented within the system for learning and study administration that is used by students and staff at Uppsala University ("Student Portal"). It consists of an interface where the students and teachers have an overview of progress made in all individual courses at the programme. For each course that includes an oral presentation, there is a folder where each student uploads a self assessment. In the same folder, the teachers upload their feedback as well as the feedback provided by fellow students for each oral presentation. Self assessments and feedback provide feedforward for future oral presentations. The platform was implemented in August 2014, and it has now been in use for one year within the nuclear engineering programme. Lessons learned from using the platform are presented in this work.

In order to study the effects of implementing this platform, a questionnaire was distributed to the students for the purpose of collecting information regarding their experience of giving oral presentation, their perceived skill level and their experience of practising oral presentations. The same questionnaire was distributed to the students on three occasions: before, during and after the first year of using the platform. Results from analysis of data are presented, showing that the students have experienced progression during this year.

National Category
Pedagogical Work
Identifiers
urn:nbn:se:uu:diva-267483 (URN)
Conference
5:e Utvecklingskonferensen för Sveriges ingenjörsutbildningar
Available from: 2015-11-24 Created: 2015-11-24 Last updated: 2018-04-19
Alhassan, E., Sjöstrand, H., Helgesson, P., Österlund, M., Pomp, S., Koning, A. J. & Rochman, D. (2015). Benchmark selection methodology for reactor calculations and nuclear data uncertainty reduction. Annals of Nuclear Energy
Open this publication in new window or tab >>Benchmark selection methodology for reactor calculations and nuclear data uncertainty reduction
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2015 (English)In: Annals of Nuclear Energy, ISSN 0306-4549, E-ISSN 1873-2100Article in journal (Refereed) Submitted
Abstract [en]

Criticality, reactor physics and shielding benchmarks are expected to play important roles in GEN-IV design, safety analysis and in the validation of analytical tools used to design these reactors. For existing reactor technology, benchmarks are used for validating computer codes and for testing nuclear data libraries. Given the large number of benchmarks available, selecting these benchmarks for specic applications can be rather tedious and difficult. Until recently, the selection process has been based usually on expert judgement which is dependent on the expertise and the experience of the user and there by introducing a user bias into the process. This approach is also not suitable for the Total Monte Carlo methodology which lays strong emphasis on automation, reproducibility and quality assurance. In this paper a method for selecting these benchmarks for reactor calculation and for nuclear data uncertainty reduction based on the Total Monte Carlo (TMC) method is presented. For reactor code validation purposes, similarities between a real reactor application and one or several benchmarks are quantied using a similarity index while the Pearson correlation coecient is used to select benchmarks for nuclear data uncertainty reduction. Also, a correlation based sensitivity method is used to identify the sensitivity of benchmarks to particular nuclear reactions. Based on the benchmark selection methodology, two approaches are presented for reducing nuclear data uncertainty using integral benchmark experiments as an additional constraint in the TMC method: a binary accept/reject and a method of assigning file weights using the likelihood function. Finally, the methods are applied to a full lead-cooled fast reactor core and a set of criticality benchmarks. Signicant reductions in Pu-239 and Pb-208 nuclear data uncertainties were obtained after implementing the two methods with some benchmarks.

National Category
Other Physics Topics
Identifiers
urn:nbn:se:uu:diva-253148 (URN)
Available from: 2015-05-21 Created: 2015-05-21 Last updated: 2017-12-04Bibliographically approved
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