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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
Rakopoulos, V., Lantz, M., Solders, A., Al-Adili, A., Mattera, A., Canete, L., . . . Pomp, S. (2018). First isomeric yield ratio measurements by direct ion counting and implications for the angular momentum of the primary fission fragments. Physical Review C: Covering Nuclear Physics, 98(2), Article ID 024612.
Open this publication in new window or tab >>First isomeric yield ratio measurements by direct ion counting and implications for the angular momentum of the primary fission fragments
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2018 (English)In: Physical Review C: Covering Nuclear Physics, ISSN 2469-9985, E-ISSN 2469-9993, Vol. 98, no 2, article id 024612Article in journal (Refereed) Published
Abstract [en]

We report the first experimental determination of independent isomeric yield ratios using direct ion counting with a Penning trap, which offered such a high resolution in mass that isomeric states could be separated. The measurements were performed at the Ion Guide Isotope Separator On-Line (IGISOL) facility at the University of Jyvaskyla. The isomer production ratios of Ge-81, Y-96,Y-97 Sn-128(,1)30, and Sb-129 in the 25-MeV proton-induced fission of U-na(t) and Th-232 were studied. Three isomeric pairs (Ge-81, Y-96, and Sb-129) were measured for the first time for the U-na(t)(p, f) reaction, while all the reported yield ratios for the Th-232(p, f) reaction were determined for the first time. The comparison of the experimentally determined isomeric yield ratios with data available in the literature shows a reasonable agreement, except for the case of Sn-130 for unspecified reasons. The obtained results were also compared with the GEF model, where good agreement can be noticed in most cases for both reactions. Serious discrepancies can only be observed for the cases of Y-96(,)97 for both reactions. Moreover, based on the isomeric yield ratios, the root-mean-square angular momenta (J(r)(ms)) of the fission fragments after scission were estimated using the TALYS code. The experimentally determined isomeric yield ratios, and consequently the deduced J(rms), for Sn-130 are significantly lower compared to Sn-128 for both fissioning systems. This can be attributed to the more spherical shape of the fragments that contribute to the formation of Sn-130, due to their proximity to the N = 82 shell closure. The values of J(rms) for Sb-129 are higher than Sn-128 for both reactions, despite the same neutron number of both nuclides (N = 78), indicating the odd-Z effect where fission fragments with odd-Z number tend to bear larger angular momentum than even-Z fragments. The isomer production ratio for the isotopes of Sn is more enhanced in the U-na(t)(p, f) reaction than in Th-232(p, f). The opposite is observed for Y-96 and Y-97. These discrepancies might be associated to different scission shapes of the fragments for the two fission reactions, indicating the impact that the different fission modes can have on the isomeric yield ratios.

Place, publisher, year, edition, pages
AMER PHYSICAL SOC, 2018
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-362692 (URN)10.1103/PhysRevC.98.024612 (DOI)000441464600003 ()
Funder
EU, FP7, Seventh Framework Programme, 605203Swedish Radiation Safety AuthoritySwedish Nuclear Fuel and Waste Management Company, SKBAcademy of Finland, 275389 284516 312544 295207
Available from: 2018-10-18 Created: 2018-10-18 Last updated: 2018-11-06Bibliographically approved
Pomp, S., Mattera, A., Rakopoulos, V., Al-Adili, A., Lantz, M., Solders, A., . . . Rinta-Antila, S. (2018). Measurement of fission yields and isomeric yield ratios at IGISOL. 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 00017.
Open this publication in new window or tab >>Measurement of fission yields and isomeric yield ratios at IGISOL
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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 00017Conference paper, Published paper (Refereed)
Abstract [en]

Data on fission yields and isomeric yield ratios (IYR) are tools to study the fission process, in particular the generation of angular momentum. We use the IGISOL facility with the Penning trap JYFLTRAP in Jyvaskyla, Finland, for such measurements on Th-232 and U-nat targets. Previously published fission yield data from IGISOL concern the Th-232(p,f) and U-238(p,f) reactions at 25 and 50 MeV. Recently, a neutron source, using the Be(p,n) reaction, has been developed, installed and tested. We summarize the results for (p,f) focusing on the first measurement of IYR by direct ion counting. We also present first results for IYR and relative yields for Sn and Sb isotopes in the 128-133 mass range from U-nat(n,f) based on gamma-spectrometry. We find a staggering behaviour in the cumulative yields for Sn and a shift in the independent fission yields for Sb as compared to current evaluations. Plans for the future experimental program on fission yields and IYR measurements are discussed.

Series
EPJ Web of Conferences, ISSN 2100-014X ; 169
National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-361441 (URN)10.1051/epjconf/201816900017 (DOI)000433153800016 ()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: 2018-12-10Bibliographically approved
Mattera, A., Pomp, S., Lantz, M., Solders, A., Rakopoulos, V., Al-Adili, A., . . . Gorelov, D. (2018). Production of Sn and Sb isotopes in high-energy neutron induced fission of natU. European Physical Journal A, 54, Article ID 33.
Open this publication in new window or tab >>Production of Sn and Sb isotopes in high-energy neutron induced fission of natU
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2018 (English)In: European Physical Journal A, ISSN 1434-6001, E-ISSN 1434-601X, Vol. 54, article id 33Article in journal (Refereed) Published
Abstract [en]

The first systematic measurement of neutron-induced fission yields has been performed at the upgraded IGISOL-4 facility at the University of Jyvaskyla, Finland. The fission products from high-energy neutron-induced fission of U-nat were stopped in a gas cell filled with helium buffer gas, and were online separated with a dipole magnet. The isobars, with masses in the range A = 128-133, were transported to a tape-implantation station and identified using gamma-spectroscopy. We report here the relative cumulative isotopic yields of tin (Z = 50) and the relative independent isotopic yields of antimony (Z = 51). Isomeric yield ratios were also obtained for five nuclides. The yields of tin show a staggered behaviour around A = 131, not observed in the ENDF/B-VII. 1 evaluation. The yields of antimony also contradict the trend from the evaluation, but are in agreement with a calculation performed using the GEF model that shows the yield increasing with mass in the range A = 128-133.

National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-328572 (URN)10.1140/epja/i2018-12462-1 (DOI)000428637900002 ()
Funder
EU, FP7, Seventh Framework Programme, 605203Swedish Radiation Safety AuthoritySwedish Nuclear Fuel and Waste Management Company, SKB
Available from: 2017-08-26 Created: 2017-08-26 Last updated: 2018-11-06Bibliographically approved
Hambsch, F.-J. -., Gamboni, T., Geerts, W., Gook, A., Oberstedt, S., Vidali, M., . . . Pomp, S. (2018). Prompt Neutron Emission Correlations with Fission Fragment Properties. In: Hamilton, JH Ramayya, AV Talou, P (Ed.), Fission And Properties Of Neutron-Rich Nuclei: Proceedings of the Sixth International Conference on ICFN6. Paper presented at Sixth International Conference on Fission and Properties of Neutron-Rich Nuclei (ICFN6), November 6 - 12 2016, Florida, United States (pp. 503-512). World Scientific
Open this publication in new window or tab >>Prompt Neutron Emission Correlations with Fission Fragment Properties
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2018 (English)In: Fission And Properties Of Neutron-Rich Nuclei: Proceedings of the Sixth International Conference on ICFN6 / [ed] Hamilton, JH Ramayya, AV Talou, P, World Scientific, 2018, p. 503-512Conference paper, Published paper (Refereed)
Abstract [en]

The investigation of the dynamics of the nuclear fission process has been a standing research topic at the JRC-Geel during the past decades. Recently the focus was put on the de-excitation of fission fragments through the emission of prompt neutrons and gamma-rays. To this end new detector systems were developed at JRC-Geel, e.g. a position sensitive ionization chamber used in conjunction with the neutron scintillator array SCINTIA. The array has been tested using the spontaneous fission of Cf-252. The goal is to study correlations of fission fragments with prompt neutron emission in the resolved resonance region. No strong fluctuations of the average prompt neutron multiplicity for the strongest resonances in U-235 were observed. From the present data the mass-dependent neutron multiplicity, v(A), was generated. The v(A) distribution shows a more pronounced dip around the doubly magic mass A = 132 and at very low masses around A similar to 80 compared to the literature. In addition, a steeper slope for v(TKE) is observed. Cross checking with fragment data clearly shows a narrower mass and total kinetic energy (TKE) distribution. The 2E-2v spectrometer VERDI (VElocity foR Direct mass Identification) became operational. For Cf-252(sf) superior mass resolution is observed compared to a twin Frisch-grid ionization chamber. For post-neutron mass distributions still some issues need to be solved and v(A), being the difference of pre- and post-neutron mass distributions, is still deviating from literature data. Eventually, VERDI will provide a complementary measurement technique to assess v(A) and v(TKE). In addition, an experimental campaign to measure v(A) as a function of incident neutron energy for different actinides has been started. First tests show promising results.

Place, publisher, year, edition, pages
World Scientific, 2018
Keywords
Neutron Induced Fission, Prompt Neutron Emission, 2E-2v Spectrometer VERDI
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-365883 (URN)10.1142/9789813229426_0090 (DOI)000435216000090 ()978-981-3229-43-3 (ISBN)
Conference
Sixth International Conference on Fission and Properties of Neutron-Rich Nuclei (ICFN6), November 6 - 12 2016, Florida, United States
Available from: 2018-11-20 Created: 2018-11-20 Last updated: 2018-11-20Bibliographically approved
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
Jansson, K., Al-Adili, A., Andersson Sundén, E., Göök, A., Stephan, O. & Pomp, S. (2018). The impact of neutron emission on correlated fission data from the 2E-2v method. European Physical Journal A, 54, Article ID 114.
Open this publication in new window or tab >>The impact of neutron emission on correlated fission data from the 2E-2v method
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2018 (English)In: European Physical Journal A, ISSN 1434-6001, E-ISSN 1434-601X, Vol. 54, article id 114Article in journal (Refereed) Published
Abstract [en]

The double-energy double-velocity (2E-2v) method allows assessing fission-fragment mass yields prior to and after prompt neutron emission with high resolution. It is, therefore, considered as a complementary technique to assess average prompt neutron multiplicity as a function of fragment properties. We have studied the intrinsic features of the 2E-2v method by means of event-wise generated fission-fragment data and found short-comings in the method itself as well as in some common practices of application. We find that the 2E-2v method leads to large deviations in the correlation between the prompt neutron multiplicity and pre-neutron mass, which deforms and exaggerates the so-called “sawtooth” shape of nubar(A). We have identified the treatment of prompt neutron emission from the fragments as the origin of the problem. The intrinsic nature of this deficiency risks to render 2E-2v experiments less interesting. We suggest a method to correct 2E-2v data that can even be applied on existing measurements.

Keywords
fission, 2E-2v, neutron
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-355518 (URN)10.1140/epja/i2018-12544-0 (DOI)000437217400002 ()
Funder
EU, FP7, Seventh Framework Programme, 605203
Available from: 2018-06-30 Created: 2018-06-30 Last updated: 2018-09-13Bibliographically approved
Ledoux, X., Aiche, M., Avrigeanu, M., Avrigeanu, V., Balanzat, E., Ban-d'Etat, B., . . . Varignon, C. (2018). The Neutrons for Science Facility at SPIRAL-2. Paper presented at 13th Symposium on Neutron and Ion Dosimetry (NEUDOS), MAY 13-19, 2017, Polish Acad Sci, Inst Nucl Phys, Krakow, POLAND. Radiation Protection Dosimetry, 180(1-4), 115-119
Open this publication in new window or tab >>The Neutrons for Science Facility at SPIRAL-2
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2018 (English)In: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 180, no 1-4, p. 115-119Article in journal (Refereed) Published
Abstract [en]

The neutrons for science (NFS) facility is a component of SPIRAL-2, the new superconducting linear accelerator built at GANIL in Caen (France). The proton and deuteron beams delivered by the accelerator will allow producing intense neutron fields in the 100 keV-40 MeV energy range. Continuous and quasi-mono-kinetic energy spectra, respectively, will be available at NFS, produced by the interaction of a deuteron beam on a thick Be converter and by the Li-7(p, n) reaction on thin converter. The pulsed neutron beam, with a flux up to two orders of magnitude higher than those of other existing time-of-flight facilities, will open new opportunities of experiments in fundamental research as well as in nuclear data measurements. In addition to the neutron beam, irradiation stations for neutron-, proton- and deuteron-induced reactions will be available for cross-sections measurements and for the irradiation of electronic devices or biological cells. NFS, whose first experiment is foreseen in 2018, will be a very powerful tool for physics, fundamental research as well as applications like the transmutation of nuclear waste, design of future fission and fusion reactors, nuclear medicine or test and development of new detectors.

Place, publisher, year, edition, pages
OXFORD UNIV PRESS, 2018
National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-364997 (URN)10.1093/rpd/ncx257 (DOI)000440983000025 ()29177426 (PubMedID)
Conference
13th Symposium on Neutron and Ion Dosimetry (NEUDOS), MAY 13-19, 2017, Polish Acad Sci, Inst Nucl Phys, Krakow, POLAND
Available from: 2018-11-08 Created: 2018-11-08 Last updated: 2019-02-28Bibliographically approved
Mattera, A., Al-Adili, A., Lantz, M., Pomp, S., Rakopoulos, V. & Solders, A. (2017). A methodology for the intercomparison of nuclear fission codes using TALYS. In: Plompen, A.; Hambsch, FJ.; Schillebeeckx, P.; Mondelaers, W.; Heyse, J.; Kopecky, S.; Siegler, P.; Oberstedt, S. (Ed.), ND 2016: International Conference On Nuclear Data For Science And Technology. Paper presented at ND 2016: International Conference on Nuclear Data for Science and Technology, September 11-16, 2016, Bruges, Belgium.. Les Ulis: EDP Sciences, 146, Article ID 04047.
Open this publication in new window or tab >>A methodology for the intercomparison of nuclear fission codes using TALYS
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2017 (English)In: ND 2016: International Conference On Nuclear Data For Science And Technology / [ed] Plompen, A.; Hambsch, FJ.; Schillebeeckx, P.; Mondelaers, W.; Heyse, J.; Kopecky, S.; Siegler, P.; Oberstedt, S., Les Ulis: EDP Sciences, 2017, Vol. 146, article id 04047Conference paper, Published paper (Refereed)
Abstract [en]

Codes for the calculation of fission observables are frequently used to describe experimentally observed phenomena as well as provide predictions in cases where measurements are missing. Assumptions in the models, and tuning of parameters within the codes, often result in a good reproduction of experimental data. In this work we propose a methodology, coded in the newly developed program DELFIN (De-Excitation of FIssion fragmeNts), that can be used to compare some of the assumptions of the various models. Our code makes use of the fission fragments information after scission and processes them in an independent and consistent fashion to obtain measurable fission observables (such as ν(A) distributions and Isomeric Fission Yield ratios). All the available information from the models, such as fragments' excitation energies, spin distributions and yields are provided as input to DELFIN that uses the nuclear reaction code TALYS to handle the de-excitation of the fission fragments. In this way we decouple the fragments relaxation from the actual fission models. We report here the first results of a comparison carried out on the GEF, Point-by-Point and FREYA models for thermal fission of 235U and 239Pu and spontaneous fission of 252Cf.

Place, publisher, year, edition, pages
Les Ulis: EDP Sciences, 2017
Series
EPJ Web of Conferences, ISSN 2100-014X
National Category
Subatomic Physics
Research subject
Physics with specialization in Applied Nuclear Physics
Identifiers
urn:nbn:se:uu:diva-317442 (URN)10.1051/epjconf/201714604047 (DOI)000426429500146 ()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 Nuclear Fuel and Waste Management Company, SKBSwedish Radiation Safety Authority
Available from: 2017-03-14 Created: 2017-03-14 Last updated: 2018-07-03Bibliographically approved
Mattera, A., Pomp, S., Lantz, M., Rakopoulos, V., Solders, A., Al-Adili, A., . . . Eronen, T. (2017). A neutron source for IGISOL-JYFLTRAP: Design and characterisation. European Physical Journal A, 53(173)
Open this publication in new window or tab >>A neutron source for IGISOL-JYFLTRAP: Design and characterisation
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2017 (English)In: European Physical Journal A, ISSN 1434-6001, E-ISSN 1434-601X, Vol. 53, no 173Article in journal (Refereed) Published
Abstract [en]

A white neutron source based on the Be(p,nx) reaction for fission studies at the IGISOLJYFLTRAP facility has been designed and tested. 30 MeV protons impinge on a 5mm thick water-cooled beryllium disc. The source was designed to produce at least 1012 fast neutrons/s on a secondary fission target, in order to reach competitive production rates of fission products far from the valley of stability.

The Monte Carlo codes MCNPX and FLUKA were used in the design phase to simulate the neutron energy spectra. Two experiments to characterise the neutron field were performed: the first was carried out at The Svedberg Laboratory in Uppsala (SE), using an Extended-Range Bonner Sphere Spectrometer and a liquid scintillator which used the time-of-flight (TOF) method to determine the energy of the neutrons; the second employed Thin-Film Breakdown Counters for the measurement of the TOF, and activation foils, at the IGISOL facility in Jyväskylä (FI). Design considerations and the results of the two characterisation measurements are presented, providing benchmarks for the simulations.

National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-328569 (URN)10.1140/epja/i2017-12362-x (DOI)000408661200001 ()
Funder
Swedish Radiation Safety AuthoritySwedish Nuclear Fuel and Waste Management Company, SKB
Available from: 2017-08-26 Created: 2017-08-26 Last updated: 2017-12-01Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-1990-5083

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