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Andersson, P., Rathore, V., Senis, L., Anastasiadis, A., Andersson Sundén, E., Atak, H., . . . Nyberg, J. (2020). Simulation of the response of a segmented High-Purity Germanium detector for gamma emission tomography of nuclear fuel. SN Applied Sciences, 2, Article ID 271.
Open this publication in new window or tab >>Simulation of the response of a segmented High-Purity Germanium detector for gamma emission tomography of nuclear fuel
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2020 (English)In: SN Applied Sciences, ISSN 2523-3963, Vol. 2, article id 271Article in journal (Refereed) Published
Abstract [en]

Irradiation testing of nuclear fuel is routinely performed in nuclear test reactors. For qualification and licensing of Accident Tolerant Fuels or Generation IV reactor fuels, an extensive increase in irradiation testing is foreseen in order to fill the gaps of existing validation data, both in normal operational conditions and in order to identify operational limits.

Gamma Emission Tomography (GET) has been demonstrated as a viable technique for studies of the behavior of irradiated nuclear fuel, e.g. measurement of fission gas release and inspection of fuel behavior under Loss-Of-Coolant Accident conditions. In this work, the aim is to improve the technique of GET for irradiated nuclear fuel by developing a detector concept for an improved tomography system that allows for a higher spatial resolution and/or faster interrogation.

We present the working principles of a novel concept for gamma emission tomography using a segmented High Purity Germanium (HPGe) detector. The performance of this concept was investigated using the Monte Carlo particle transport code MCNP. In particular, the data analysis of the proposed detector was evaluated, and the performance, in terms of full energy efficiency and localization failure rate, has been evaluated.

We concluded that the segmented HPGe detector has an advantageous performance as compared to the traditional single-channel detector systems. Due to the scattering nature of gamma rays, a trade-off is presented between efficiency and cross-talk; however, the performance is nevertheless a substantial improvement over the currently used single-channel HPGe detector systems.

Place, publisher, year, edition, pages
Springer, 2020
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-392188 (URN)10.1007/s42452-020-2053-4 (DOI)
Funder
Swedish Research Council, 2017-06448Swedish Foundation for Strategic Research , EM16-0031
Available from: 2019-08-30 Created: 2019-08-30 Last updated: 2020-02-17Bibliographically approved
Ralet, D., Clement, E., Georgiev, G., Stuchbery, A. E., Rejmund, M., Van Isacker, R., . . . Wieland, O. (2019). Evidence of octupole-phonons at high spin in Pb-207. Physics Letters B, 797, Article ID UNSP 134797.
Open this publication in new window or tab >>Evidence of octupole-phonons at high spin in Pb-207
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2019 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 797, article id UNSP 134797Article in journal (Refereed) Published
Abstract [en]

A lifetime measurement of the 19/2(-) state in Pb-207 has been performed using the Recoil Distance Doppler-Shift (RDDS) method. The nuclei of interest were produced in multi-nucleon transfer reactions induced by a Pb-208 beam impinging on a Mo-100 enriched target. The beam-like nuclei were detected<bold> </bold>and identified in terms of their atomic mass number in the VAMOS++ spectrometer while the prompt gamma rays were detected by the AGATA tracking array. The measured large reduced transition probability B(E3, 19/2(-) -> 13/2(+)) = 40(8) W.u. is the first indication of the octupole phonon at high spin in Pb-207. An analysis in terms of a particle-octupole-vibration coupling model indicates that the measured B(E3) value in Pb-207 is compatible with the contributions from single-phonon and single particle E3 as well as E3 strength arising from the double-octupole-phonon 6(+) state, all adding coherently. A crucial aspect of the coupling model, namely the strong mixing between single-hole and the phonon-hole states, is confirmed in a realistic shell-model calculation. Crown Copyright (C) 2019 Published by Elsevier B.V.<bold> </bold>

Place, publisher, year, edition, pages
ELSEVIER, 2019
Keywords
AGATA spectrometer, gamma-Ray tracking, VAMOS plus plus spectrometer, Plunger device, Nuclear deformation, Octupole phonon
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-395717 (URN)10.1016/j.physletb.2019.134797 (DOI)000488071200015 ()
Funder
EU, FP7, Seventh Framework Programme, 262010
Available from: 2019-10-24 Created: 2019-10-24 Last updated: 2019-10-24Bibliographically approved
Boso, A., Milne, S. A., Bentley, M. A., Recchia, F., Lenzi, S. M., Rudolph, D., . . . Wieland, O. (2019). Isospin dependence of electromagnetic transition strengths among an isobaric triplet. Physics Letters B, 797, Article ID UNSP 134835.
Open this publication in new window or tab >>Isospin dependence of electromagnetic transition strengths among an isobaric triplet
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2019 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 797, article id UNSP 134835Article in journal (Refereed) Published
Abstract [en]

Electric quadrupole matrix elements, M-p, for the J(pi) = 2(+) -> 0(+), Delta T = 0, T = 1 transitions across the A = 46 isobaric multiplet Cr-46-V-46-Ti-46 have been measured at GSI with the FRS-LYCCA-AGATA setup. This allows direct insight into the isospin purity of the states of interest by testing the linearity of M-p with respect to T-z. Pairs of nuclei in the T = 1 triplet were studied using identical reaction mechanisms in order to control systematic errors. The M-p values were obtained with two different methodologies: (i) a relativistic Coulomb excitation experiment was performed for Cr-46 and Ti-46; (ii) a "stretched target" technique was adopted here, for the first time, for lifetime measurements in V-46 and Ti-46. A constant value of M-p across the triplet has been observed. Shell-model calculations performed within the fp shell fail to reproduce this unexpected trend, pointing towards the need of a wider valence space. This result is confirmed by the good agreement with experimental data achieved with an interaction which allows excitations from the underlying sd shell. A test of the linearity rule for all published data on complete T = 1 isospin triplets is presented. (C) 2019 The Author(s). Published by Elsevier B.V.

Place, publisher, year, edition, pages
ELSEVIER, 2019
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-395716 (URN)10.1016/j.physletb.2019.134835 (DOI)000488071200023 ()
Funder
EU, FP7, Seventh Framework Programme, 262010Swedish Research Council, 2010-147Swedish Research Council, 2011-5253Swedish Research Council, 2011-6127
Available from: 2019-10-25 Created: 2019-10-25 Last updated: 2019-10-25Bibliographically approved
Goldkuhle, A., Fransen, C., Blazhev, A., Beckers, M., Birkenbach, B., Braunroth, T., . . . Zielinska, M. (2019). Lifetime measurements in Ti-52,Ti-54 to study shell evolution toward N=32. Physical Review C: Covering Nuclear Physics, 100(5), Article ID 054317.
Open this publication in new window or tab >>Lifetime measurements in Ti-52,Ti-54 to study shell evolution toward N=32
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2019 (English)In: Physical Review C: Covering Nuclear Physics, ISSN 2469-9985, E-ISSN 2469-9993, Vol. 100, no 5, article id 054317Article in journal (Refereed) Published
Abstract [en]

Lifetimes of the excited states in the neutron-rich Ti-52,Ti-54 nuclei, produced in a multinucleon-transfer reaction, were measured by employing the Cologne plunger device and the recoil-distance Doppler-shift method. The experiment was performed at the Grand Accelerateur National d'Ions Lourds facility by using the Advanced Gamma Tracking Array for the gamma-ray detection, coupled to the large-acceptance variable mode spectrometer for an event-by-event particle identification. A comparison between the transition probabilities obtained from the measured lifetimes of the 2(1)(+) to 8(1)(+) yrast states in Ti-52,Ti-54 and that from the shell-model calculations based on the well-established GXPF1A, GXPF1B, and KB3G fp shell interactions support the N = 32 subshell closure. The B(E2) values for Ti-52 determined in this work are in disagreement with the known data, but are consistent with the predictions of the shell-model calculations and reduce the previously observed pronounced staggering across the even-even titanium isotopes.

Place, publisher, year, edition, pages
American Physical Society, 2019
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-398687 (URN)10.1103/PhysRevC.100.054317 (DOI)000496925500001 ()
Funder
European Regional Development Fund (ERDF)
Available from: 2019-12-09 Created: 2019-12-09 Last updated: 2019-12-09Bibliographically approved
Valiente-Dobon, J. J., Jaworski, G., Goasduff, A., Egea, J., Modamio, V., Huyuk, T., . . . Zanon, I. (2019). NEDA-NEutron Detector Array. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 927, 81-86
Open this publication in new window or tab >>NEDA-NEutron Detector Array
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2019 (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. 927, p. 81-86Article in journal (Refereed) Published
Abstract [en]

The NEutron Detector Array, NEDA, will form the next generation neutron detection system that has been designed to be operated in conjunction with gamma-ray arrays, such as the tracking-array AGATA, to aid nuclear spectroscopy studies. NEDA has been designed to be a versatile device, with high-detection efficiency, excellent neutron-gamma discrimination, and high rate capabilities. It will be employed in physics campaigns in order to maximise the scientific output, making use of the different stable and radioactive ion beams available in Europe. The first implementation of the neutron detector array NEDA with AGATA 1 pi was realised at GANIL. This manuscript reviews the various aspects of NEDA.

Keywords
NEDA, Nuclear structure, Gamma-ray spectroscopy, Neutron detector, Liquid scintillator, Digital electronics, Neutron-gamma discrimination
National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-382241 (URN)10.1016/j.nima.2019.02.021 (DOI)000462142700010 ()
Funder
Swedish Research Council, VR 2014-6644
Available from: 2019-05-16 Created: 2019-05-16 Last updated: 2019-05-16Bibliographically approved
Söderström, P.-A., Jaworski, G., Dobon, J. J., Nyberg, J., Agramunt, J., de Angelis, G., . . . Wadsworth, R. (2019). Neutron detection and gamma-ray suppression using artificial neural networks with the liquid scintillators BC-501A and BC-537. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 916, 238-245
Open this publication in new window or tab >>Neutron detection and gamma-ray suppression using artificial neural networks with the liquid scintillators BC-501A and BC-537
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2019 (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. 916, p. 238-245Article in journal (Refereed) Published
Abstract [en]

In this work we present a comparison between the two liquid scintillators BC-501A and BC-537 in terms of their performance regarding the pulse-shape discrimination between neutrons and gamma rays. Special emphasis is put on the application of artificial neural networks. The results show a systematically higher gamma-ray rejection ratio for BC-501A compared to BC-537 applying the commonly used charge comparison method. Using the artificial neural network approach the discrimination quality was improved to more than 95% rejection efficiency of gamma rays over the energy range 150 to 1000 keV for both BC-501A and BC-537. However, due to the larger light output of BC-501A compared to BC-537, neutrons could be identified in BC-501A using artificial neural networks down to a recoil proton energy of 800 keV compared to a recoil deuteron energy of 1200 keV for BC-537. We conclude that using artificial neural networks it is possible to obtain the same gamma-ray rejection quality from both BC-501A and BC-537 for neutrons above a low-energy threshold. This threshold is, however, lower for BC-501A, which is important for nuclear structure spectroscopy experiments of rare reaction channels where low-energy interactions dominates.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2019
Keywords
BC-501A, BC-537, Digital pulse-shape discrimination, Fast-neutron detection, Liquid scintillator, Neural networks
National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-375216 (URN)10.1016/j.nima.2018.11.122 (DOI)000455016800033 ()
Funder
Swedish Research Council
Available from: 2019-01-31 Created: 2019-01-31 Last updated: 2019-01-31Bibliographically approved
Jaworski, G., Goasduff, A., Canet, F. J., Modamio, V., Huyuk, T., Triossi, A., . . . Zanon, I. (2019). The New Neutron Multiplicity Filter NEDA and Its First Physics Campaign with AGATA. Paper presented at Zakopane Conference on Nuclear Physics - Extremes of the Nuclear Landscape, AUG 26-SEP 02, 2018, Zakopane, POLAND. Acta Physica Polonica B, 50(3), 585-590
Open this publication in new window or tab >>The New Neutron Multiplicity Filter NEDA and Its First Physics Campaign with AGATA
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2019 (English)In: Acta Physica Polonica B, ISSN 0587-4254, E-ISSN 1509-5770, Vol. 50, no 3, p. 585-590Article in journal (Refereed) Published
Abstract [en]

A new neutron multiplicity filter NEDA, after a decade of design, R&D and construction, was employed in its first physics campaign with the AGATA spectrometer. Properties and performance of the array are discussed.

National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-382664 (URN)10.5506/APhysPolB.50.585 (DOI)000463866500047 ()
Conference
Zakopane Conference on Nuclear Physics - Extremes of the Nuclear Landscape, AUG 26-SEP 02, 2018, Zakopane, POLAND
Funder
Swedish Research Council, VR 2014-6644
Available from: 2019-05-07 Created: 2019-05-07 Last updated: 2019-05-07Bibliographically approved
Ertoprak, A., Cederwall, B., Qi, C., Doncel, M., Jakobsson, U., Nyako, B. M., . . . Xiao, Z. G. (2018). M1 And E2 Transition Rates From Core-Excited States In Semi-Magic Ru-94. European Physical Journal A, 54(9), Article ID 145.
Open this publication in new window or tab >>M1 And E2 Transition Rates From Core-Excited States In Semi-Magic Ru-94
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2018 (English)In: European Physical Journal A, ISSN 1434-6001, E-ISSN 1434-601X, Vol. 54, no 9, article id 145Article in journal (Refereed) Published
Abstract [en]

Lifetimes of high-spin states have been measured in the semi-magic (N = 50) nucleus Ru-94. Excited states in Ru-94 were populated in the Ni-58(Ca-40, 4p)Ru-94* fusion-evaporation reaction at the Grand Accelerateur National d'Ions Lourds (GANIL) accelerator complex. DSAM lifetime analysis was performed on the Doppler broadened line shapes in energy spectra obtained from gamma-rays emitted while the residual nuclei were slowing down in a thick 6 mg/cm(2) metallic Ni-58 target. In total eight excited-state lifetimes in the angular momentum range I = (13-20)h have been measured, five of which were determined for the first time. The corresponding B(M1) and B(E2) reduced transition strengths are discussed within the framework of large-scale shell model calculations to study the contribution of different particle-hole configurations, in particular for analyzing contributions from core-excited configurations.

National Category
Subatomic Physics Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:uu:diva-366155 (URN)10.1140/epja/i2018-12581-7 (DOI)000443091000003 ()
Funder
Swedish Research Council
Available from: 2018-11-20 Created: 2018-11-20 Last updated: 2018-11-20Bibliographically approved
Boso, A., Lenzi, S. M., Recchia, F., Bonnard, J., Zuker, A. P., Aydin, S., . . . Valiente-Dobon, J. J. (2018). Neutron Skin Effects in Mirror Energy Differences: The Case of Mg-23-Na-23. Physical Review Letters, 121(3), Article ID 032502.
Open this publication in new window or tab >>Neutron Skin Effects in Mirror Energy Differences: The Case of Mg-23-Na-23
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2018 (English)In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 121, no 3, article id 032502Article in journal (Refereed) Published
Abstract [en]

Energy differences between analogue states in the T = 1/2 Mg-23-Na-23 mirror nuclei have been measured along the rotational yrast bands. This allows us to search for effects arising from isospin-symmetrybreaking interactions (ISB) and/or shape changes. Data are interpreted in the shell model framework following the method successfully applied to nuclei in the f(7/2) shell. It is shown that the introduction of a schematic ISB interaction of the same type of that used in the f(7/2) shell is needed to reproduce the data. An alternative novel description, applied here for the first time, relies on the use of an effective interaction deduced from a realistic charge-dependent chiral nucleon-nucleon potential. This analysis provides two important results: (i) The mirror energy differences give direct insight into the nuclear skin; (ii) the skin changes along the rotational bands are strongly correlated with the difference between the neutron and proton occupations of the s(1/2) "halo" orbit.

Place, publisher, year, edition, pages
AMER PHYSICAL SOC, 2018
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-361688 (URN)10.1103/PhysRevLett.121.032502 (DOI)000439286800004 ()
Funder
EU, FP7, Seventh Framework Programme, 262010 ENSAR FP7/2007-2013
Available from: 2018-10-03 Created: 2018-10-03 Last updated: 2018-10-03Bibliographically approved
Delafosse, C., Verney, D., Marevic, P., Gottardo, A., Michelagnoli, C., Lemasson, A., . . . Dobon, J. J. (2018). Pseudospin Symmetry and Microscopic Origin of Shape Coexistence in the Ni-78 Region: A Hint from Lifetime Measurements. Physical Review Letters, 121(19), Article ID 192502.
Open this publication in new window or tab >>Pseudospin Symmetry and Microscopic Origin of Shape Coexistence in the Ni-78 Region: A Hint from Lifetime Measurements
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2018 (English)In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 121, no 19, article id 192502Article in journal (Refereed) Published
Abstract [en]

Lifetime measurements of excited states of the light N = 52 isotones Kr-88, Se-86, and Ge-84 have been performed, using the recoil distance Doppler shift method and VAMOS and AGATA spectrometers for particle identification and gamma spectroscopy, respectively. The reduced electric quadrupole transition probabilities B(E2; 2(+)-> 0(+)) and B(E2; 4(+)-> 2(+)) were obtained for the first time for the hard-to-reach 84Ge. While the B(E2; 2(+)-> 0(+) ) values of Kr-88, Se-86 saturate the maximum quadrupole collectivity offered by the natural valence (3s, 2d, 1g(7/2), 1h(11/2)) space of an inert Ni-78 core, the value obtained for Ge-84 largely exceeds it, suggesting that shape coexistence phenomena, previously reported at N less than or similar to 49, extend beyond N = 50. The onset of collectivity at Z = 32 is understood as due to a pseudo-SU(3) organization of the proton single-particle sequence reflecting a clear manifestation of pseudospin symmetry. It is realized that the latter provides actually reliable guidance for understanding the observed proton and neutron single particle structure in the whole medium-mass region, from Ni to Sn, pointing towards the important role of the isovector-vector rho field in shell-structure evolution.

Place, publisher, year, edition, pages
AMER PHYSICAL SOC, 2018
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-371499 (URN)10.1103/PhysRevLett.121.192502 (DOI)000449791600008 ()30468583 (PubMedID)
Funder
EU, FP7, Seventh Framework Programme, 262010
Available from: 2018-12-21 Created: 2018-12-21 Last updated: 2018-12-21Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0001-6996-7605

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