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Cannarozzo, S., Pomp, S., Solders, A., Al-Adili, A., Gao, Z., Lantz, M., . . . Raggio, A. (2025). Disentangling the influence of excitation energy and compound nucleus angular momentum on fission fragment angular momentum. Physical Review C: Covering Nuclear Physics, 111(3), Article ID L031601.
Open this publication in new window or tab >>Disentangling the influence of excitation energy and compound nucleus angular momentum on fission fragment angular momentum
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2025 (English)In: Physical Review C: Covering Nuclear Physics, ISSN 2469-9985, E-ISSN 2469-9993, Vol. 111, no 3, article id L031601Article in journal (Refereed) Published
Abstract [en]

The origin of the large angular momenta observed for fission fragments is still a question under discussion. To address this, we study isomeric yield ratios (IYRs), i.e., the relative population of two or more long-lived metastable states with different spins, of fission products. We report on IYRs of 17 isotopes produced in the 28-MeV 𝛼-induced fission of 232Th at the IGISOL facility of the University of Jyväskylä. The fissioning nuclei in this reaction are 233,234,235U*. We compare our data to IYRs from thermal neutron-induced fission of 233U and 235U, and we observe statistically significant larger IYRs in the 232Th(𝛼, 𝑓) reaction, where the average compound nucleus (CN) spin is 7.7 ℏ, than in 233,235U(𝑛th, 𝑓), with average spins of 2.6 and 3.6 ℏ, respectively. To assess the influence of the excitation energy, we study literature data of IYRs from photon-induced fission reactions, and find that, within current uncertainties, the IYRs indicate no dependency of the CN excitation energy. We conclude that the different IYRs seem to be due to the different CN spins alone. This would imply that the fission fragment angular momentum only partly comes from the fission process itself and is, in addition, influenced by the angular momentum present in the CN.

Place, publisher, year, edition, pages
American Physical Society, 2025
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-554443 (URN)10.1103/PhysRevC.111.L031601 (DOI)001460110100001 ()2-s2.0-105001114967 (Scopus ID)
Available from: 2025-04-14 Created: 2025-04-14 Last updated: 2025-05-09Bibliographically approved
Cannarozzo, S., Pomp, S., Kankainen, A., Moore, I., Stryjczyk, M., Al-Adili, A., . . . Ruotsalainen, J. (2025). Isomeric yield ratios and mass spectrometry of Y and Nb isotopes in the neutron-rich N=60 region: the unusual case of $^98$Y.
Open this publication in new window or tab >>Isomeric yield ratios and mass spectrometry of Y and Nb isotopes in the neutron-rich N=60 region: the unusual case of $^98$Y
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2025 (English)Other (Other academic)
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-554774 (URN)
Available from: 2025-04-16 Created: 2025-04-16 Last updated: 2025-05-09
Karlsson, P., Al-Adili, A., Göök, A., Gao, Z., Pomp, S., Sjöstrand, H., . . . Koning, A. (2025). Modeling Pu-239 Fission Fragment De-Excitation applying the Total Monte Carlo method in TALYS. In: Dimitriou, P Capote, R Schnabel, G (Ed.), 7TH INTERNATIONAL WORKSHOP ON COMPOUND-NUCLEAR REACTIONS AND RELATED TOPICS, CNR*24: . Paper presented at 7th International Workshop on Compound-Nuclear Reactions and Related Topics-CNR, JUL 08-12, 2024, Vienna, AUSTRIA. EDP Sciences, 322, Article ID 07005.
Open this publication in new window or tab >>Modeling Pu-239 Fission Fragment De-Excitation applying the Total Monte Carlo method in TALYS
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2025 (English)In: 7TH INTERNATIONAL WORKSHOP ON COMPOUND-NUCLEAR REACTIONS AND RELATED TOPICS, CNR*24 / [ed] Dimitriou, P Capote, R Schnabel, G, EDP Sciences, 2025, Vol. 322, article id 07005Conference paper, Published paper (Refereed)
Abstract [en]

In this study, we applied the Total Monte Carlo (TMC) methodology in de-excitation simulations of primary fission fragments (FF) using the TALYS code. The goal was to develop and optimise a methodology to benchmark initial fission model assumptions on fission mass yield distributions, excitation energy sharing and angular momentum population. The study was performed on the thermal neutron induced fission of Pu-239(n(th),f). The work aimed at evaluating fission model deficiencies and parameter sensitivities. We systematically varied TALYS input data by generating 5000 random files through the GEF code, randomizing 94 model parameters that affect fission yields and energy distributions within 3% of their default values. This variation revealed significant changes in the fission observables, such as prompt neutron and gamma-ray multiplicities and energy spectra. The results indicate some systematic defects in the assumed excitation-energies and angular momenta. Another outcome from the study is the identification of a need for new correlation measurements on prompt neutrons and gamma-rays from the Pu-239(n(th),f) reaction, as well as an updated evaluation.

Place, publisher, year, edition, pages
EDP Sciences, 2025
Series
EPJ Web of Conferences, ISSN 2100-014X
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-556713 (URN)10.1051/epjconf/202532207005 (DOI)001453120000032 ()2-s2.0-105002340927 (Scopus ID)
Conference
7th International Workshop on Compound-Nuclear Reactions and Related Topics-CNR, JUL 08-12, 2024, Vienna, AUSTRIA
Funder
Swedish Research Council, 2019-05385Swedish Energy Agency, P2023-01281
Available from: 2025-05-20 Created: 2025-05-20 Last updated: 2025-05-20Bibliographically approved
Cannarozzo, S., Pomp, S., Solders, A., Al-Adili, A., Gao, Z. & Lantz, M. (2025). Phase-Imaging Ion Cyclotron Resonance data analysis for isomeric yield ratios measurement. In: : . Paper presented at 7th International Workshop on Compound-Nuclear Reactions and Related Topics (CNR*24). EDP Sciences, 322
Open this publication in new window or tab >>Phase-Imaging Ion Cyclotron Resonance data analysis for isomeric yield ratios measurement
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2025 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Isomeric yield ratios (IYR) are an important tool to study the angular momentum generation in nuclear fission and to investigate the possible influence on the spin of the compound nucleus formed in a fission reaction. One method to measure the IYR is to use the Phase-Imaging Ion-Cyclotron-Resonance (PI-ICR) technique. The PI-ICR is a direct ion counting technique based on the spatial separation of ions trapped in a circular motion and their projection onto a position-sensitive detector. Here the analysis routine is presented for the PI-ICR images produced to study 21 fission products formed by the 32 MeV α-induced fission of 232Th at the IGISOL facility.

Place, publisher, year, edition, pages
EDP Sciences, 2025
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-554442 (URN)10.1051/epjconf/202532208007 (DOI)2-s2.0-105002317222 (Scopus ID)
Conference
7th International Workshop on Compound-Nuclear Reactions and Related Topics (CNR*24)
Available from: 2025-04-12 Created: 2025-04-12 Last updated: 2025-05-16Bibliographically approved
Gómez L., A. M., Al-Adili, A., Tarrío, D., Solders, A., Gao, Z., Göök, A., . . . Oberstedt, S. (2025). Plasma-delay studies on heavy ion detection using PIPS at the LOHENGRIN recoil separator. European Physical Journal A, 61(3), Article ID 51.
Open this publication in new window or tab >>Plasma-delay studies on heavy ion detection using PIPS at the LOHENGRIN recoil separator
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2025 (English)In: European Physical Journal A, ISSN 1434-6001, E-ISSN 1434-601X, Vol. 61, no 3, article id 51Article in journal (Refereed) Published
Abstract [en]

The VERDI fission spectrometer is designed to measure fragment velocities and kinetic energies to achieve high-precision yield measurements. It consists of two time-of-flight (TOF) sections, each hosting a micro-channel plate (MCP) and up to 32 passivated implanted planar silicon (PIPS) detectors. The main challenge to achieve accurate fragment velocities is the so-called plasma delay time (PDT) phenomena in the PIPS detectors. In this work, we present a dedicated experimental campaign at the LOHENGRIN fission-fragment recoil separator, to solve the pending PDT challenges. The PDT effect was systematically investigated, as a function of mass and energy, using a dedicated time-of-flight setup. In addition, the pulse height defect (PHD) was determined simultaneously. The studies were conducted for five PIPS detectors, in energies and mass numbers ranging from 20 to 110 MeV and A = 85 to 149, respectively. Using digital signal processing, an excellent timing resolution was achieved, reaching as low as 60 ps (one σ) for the heavy ions. The PDT revealed a strong positive correlation with the ion energy and a weak negative correlation with the mass. The experimental PDT values determined from five detectors confirm a consistent systematic behavior with respect to mass and energy. Some systematic discrepancies were exhibited by two detectors, possibly due to the use of different pre-amplification chains. The PDT measurements ranged between 1 and 3.5 ns, for heavy ions relative to α-particles. The PHD values showed also a strong correlation with the ion energy, and moreover with the ion mass. The PHD for heavy ions was found to range between 2 and 8 MeV, relative to α-particles. Finally, a two-dimensional parameterisation was developed to model the experimental PDT data, as a function of mass and energy. This new model, which is valid in the fission fragment mass and energy regime, will be of benefit for heavy-ion velocity measurements, using silicon detectors, as done in VERDI.

Place, publisher, year, edition, pages
Springer, 2025
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-553428 (URN)10.1140/epja/s10050-025-01509-5 (DOI)001445952100001 ()
Funder
Uppsala UniversitySwedish Research Council, 2019-05385Swedish Centre for Nuclear Technology (SKC)EU, European Research Council, 847594Swedish Energy Agency, P202301281Ingegerd Berghs stiftelseCarl Tryggers foundation
Available from: 2025-03-27 Created: 2025-03-27 Last updated: 2025-03-27Bibliographically approved
Gómez Londoño, A. M., Al-Adili, A., Tarrío, D., Solders, A., Pomp, S., Vidali, M., . . . Oberstedt, S. (2025). Recent updates in the VERDI fission-fragment spectrometer. In: Dimitriou, P Capote, R Schnabel, G (Ed.), 7TH INTERNATIONAL WORKSHOP ON COMPOUND-NUCLEAR REACTIONS AND RELATED TOPICS, CNR*24: . Paper presented at 7th International Workshop on Compound-Nuclear Reactions and Related Topics-CNR, JUL 08-12, 2024, Vienna, AUSTRIA. EDP Sciences, 322, Article ID 08008.
Open this publication in new window or tab >>Recent updates in the VERDI fission-fragment spectrometer
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2025 (English)In: 7TH INTERNATIONAL WORKSHOP ON COMPOUND-NUCLEAR REACTIONS AND RELATED TOPICS, CNR*24 / [ed] Dimitriou, P Capote, R Schnabel, G, EDP Sciences, 2025, Vol. 322, article id 08008Conference paper, Published paper (Refereed)
Abstract [en]

The VElocity foR Direct particle Identification (VERDI) is a spectrometer designed to determine fission-fragment mass distributions using the 2E-2v method, which measures both velocities and energies of the fission fragments. VERDI has two time-of-flight (TOF) sections, each with a Micro Channel Plate (MCP) Time-of-flight Start detector and up to 32 passivated implanted planar silicon (PIPS) detectors. Achieving the desired mass resolution is challenged by the need for high TOF and energy resolutions. Recent upgrades to the VERDI setup have improved its performance, achieving a TOF resolution as low as 355 ps (FWHM) and an energy resolution of 22 keV (FWHM) for alpha-particles. These enhancements in resolution demonstrate improved capabilities for achieving high-precision fission fragment yield measurements.

Place, publisher, year, edition, pages
EDP Sciences, 2025
Series
EPJ Web of Conferences, ISSN 2100-014X
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-556717 (URN)10.1051/epjconf/202532208008 (DOI)001453120000040 ()2-s2.0-105002325027 (Scopus ID)
Conference
7th International Workshop on Compound-Nuclear Reactions and Related Topics-CNR, JUL 08-12, 2024, Vienna, AUSTRIA
Funder
Swedish Research Council, 2019-05385Swedish Energy Agency, P2023-01281
Available from: 2025-05-20 Created: 2025-05-20 Last updated: 2025-05-20Bibliographically approved
de Arruda, L., Tarrío, D., Ledoux, X., Pomp, S., Ramos, D., Prokofiev, A. V., . . . Cobo, A. (2025). Reconstruction of the GANIL-NFS spectral neutron flux with Medley using elastically scattered protons. In: Dimitriou, P Capote, R Schnabel, G (Ed.), 7TH INTERNATIONAL WORKSHOP ON COMPOUND-NUCLEAR REACTIONS AND RELATED TOPICS, CNR*24: . Paper presented at 7th International Workshop on Compound-Nuclear Reactions and Related Topics-CNR, JUL 08-12, 2024, Vienna, AUSTRIA. E D P SCIENCES, 322, Article ID 08006.
Open this publication in new window or tab >>Reconstruction of the GANIL-NFS spectral neutron flux with Medley using elastically scattered protons
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2025 (English)In: 7TH INTERNATIONAL WORKSHOP ON COMPOUND-NUCLEAR REACTIONS AND RELATED TOPICS, CNR*24 / [ed] Dimitriou, P Capote, R Schnabel, G, E D P SCIENCES , 2025, Vol. 322, article id 08006Conference paper, Published paper (Refereed)
Abstract [en]

The experimental setup called Medley, has been installed at the Neutrons For Science (NFS) facility at GANIL to study the production of light-ions in neutron-induced reactions. The setup was first used to measure the neutron spectral flux from neutron-proton elastic scattering, allowing both an assessment of its performance, and providing an independent measurement of the neutron flux of the facility. The experimental setup, its performance, and the challenges encountered are presented and discussed. The deduced neutron flux is compared to the one obtained from a monitor based on position-sensitive parallel plate avalanche counters (PS-PPACs).

Place, publisher, year, edition, pages
E D P SCIENCES, 2025
Series
EPJ Web of Conferences, ISSN 2100-014X
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-556723 (URN)10.1051/epjconf/202532208006 (DOI)001453120000038 ()2-s2.0-105002340780 (Scopus ID)
Conference
7th International Workshop on Compound-Nuclear Reactions and Related Topics-CNR, JUL 08-12, 2024, Vienna, AUSTRIA
Available from: 2025-05-16 Created: 2025-05-16 Last updated: 2025-05-16Bibliographically approved
Balibrea-Correa, J., Babiano-Suarez, V., Lerendegui-Marco, J., Domingo-Pardo, C., Ladarescu, I., Tarifeno-Saldivia, A., . . . Zugec, P. (2025). Towards a new generation of solid total-energy detectors for neutron-capture time-of-flight experiments with intense neutron beams. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1072, Article ID 170110.
Open this publication in new window or tab >>Towards a new generation of solid total-energy detectors for neutron-capture time-of-flight experiments with intense neutron beams
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2025 (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. 1072, article id 170110Article in journal (Refereed) Published
Abstract [en]

Challenging neutron-capture cross-section measurements of small cross sections and samples with a very limited number of atoms require high-flux time-of-flight facilities. In turn, such facilities need innovative detection setups that are fast, have low sensitivity to neutrons, can quickly recover from the so-called. gamma-flash, and offer the highest possible detection sensitivity. In this paper, we present several steps towards such advanced systems. Specifically, we describe the performance of a high-sensitivity experimental setupat CERN n_TOF EAR2. It consists of nine sTED detector modules in a compact cylindrical configuration, two conventional used large-volume C6D6 detectors, and one LaCl3(Ce) detector. The performance of these detection systems is compared using Nb-93(n, gamma) data. We also developed a detailed GEANT4 Monte Carlo model of the experimental EAR2 setup, which allows for a better understanding of the detector features, including their efficiency determination. This Monte Carlo model has been used for further optimization, thus leading to a new conceptual design of a gamma detector array, STAR, based on a deuterated-stilbene crystal array. Finally, the suitability of deuterated-stilbene crystals for the future STAR array is investigated experimentally utilizing a small stilbene-d12 prototype. The results suggest a similar or superior performance of STAR with respect to other setups based on liquid-scintillators, and allow for additional features such as neutron-gamma discrimination and a higher level of customization capability.

Place, publisher, year, edition, pages
Elsevier, 2025
Keywords
Neutron capture, gamma-ray detectors, High sensitivity, Hybrid setup, Stilbene-d12
National Category
Subatomic Physics Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:uu:diva-547657 (URN)10.1016/j.nima.2024.170110 (DOI)001381479700001 ()2-s2.0-85211058855 (Scopus ID)
Available from: 2025-01-17 Created: 2025-01-17 Last updated: 2025-01-17Bibliographically approved
Alcayne, V., Cano-Ott, D., Garcia, J., Gonzalez-Romero, E., Martinez, T., de Rada, A. P., . . . Zugec, P. (2024). A Segmented Total Energy Detector (sTED) optimized for (n,ϒ) cross-section measurements at n_TOF EAR2. Radiation Physics and Chemistry, 217
Open this publication in new window or tab >>A Segmented Total Energy Detector (sTED) optimized for (n,ϒ) cross-section measurements at n_TOF EAR2
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2024 (English)In: Radiation Physics and Chemistry, ISSN 0969-806X, E-ISSN 1879-0895, Vol. 217Article in journal (Refereed) Published
Abstract [en]

The neutron time-of-flight facility n_TOF at CERN is a spallation source dedicated to measurements of neutroninduced reaction cross-sections of interest in nuclear technologies, astrophysics, and other applications. Since 2014, Experimental ARea 2 (EAR2) is operational and delivers a neutron fluence of similar to 4 center dot 10(7) neutrons per nominal proton pulse, which is similar to 50 times higher than the one of Experimental ARea 1 (EAR1) of similar to 8 center dot 10(5) neutrons per pulse. The high neutron flux at EAR2 results in high counting rates in the detectors that challenged the previously existing capture detection systems. For this reason, a Segmented Total Energy Detector (sTED) has been developed to overcome the limitations in the detector's response, by reducing the active volume per module and by using a photo-multiplier (PMT) optimized for high counting rates. This paper presents the main characteristics of the sTED, including energy and time resolution, response to gamma-rays, and provides as well details of the use of the Pulse Height Weighting Technique (PHWT) with this detector. The sTED has been validated to perform neutron-capture cross-section measurements in EAR2 in the neutron energy range from thermal up to at least 400 keV. The detector has already been successfully used in several measurements at n_TOF EAR2.

Place, publisher, year, edition, pages
Elsevier, 2024
Keywords
Neutron capture, PHWT, Scintillation detectors, Monte Carlo simulation
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-533307 (URN)10.1016/j.radphyschem.2024.111525 (DOI)001185584800001 ()
Note

Correction in: Radiation Physics and Chemistry, Volume 220, July 2024, Pages 111706

DOI: 10.1016/j.radphyschem.2024.111706

Available from: 2024-06-26 Created: 2024-06-26 Last updated: 2024-10-18Bibliographically approved
Pomp, S. (2024). Applied Nuclear Physics: What is going on in Sweden? (with a slight emphasis on Uppsala). In: : . Paper presented at Mini-workshop in connection with the NuPECC meeting in Lund, Sweden, 13 June, 2024.
Open this publication in new window or tab >>Applied Nuclear Physics: What is going on in Sweden? (with a slight emphasis on Uppsala)
2024 (English)Conference paper, Oral presentation only (Other academic)
National Category
Subatomic Physics
Research subject
Physics; Physics with specialization in Applied Nuclear Physics
Identifiers
urn:nbn:se:uu:diva-531717 (URN)
Conference
Mini-workshop in connection with the NuPECC meeting in Lund, Sweden, 13 June, 2024
Available from: 2024-06-14 Created: 2024-06-14 Last updated: 2024-06-17Bibliographically approved
Projects
Begäran om medel för Medley @ Ganil [2011-07560_VR]; Uppsala UniversityThe spin is the catch - studying fission with traps [2020-04238_VR]; Uppsala University
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-1990-5083

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