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Author  |
Wilson, J.N. et al; Algora, A. |
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Title |
Angular momentum generation in nuclear fission |
Type |
Journal Article |
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Year |
2021 |
Publication |
Nature |
Abbreviated Journal |
Nature |
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Volume |
590 |
Issue |
7847 |
Pages |
566-570 |
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Keywords |
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Abstract |
When a heavy atomic nucleus splits (fission), the resulting fragments are observed to emerge spinning(1); this phenomenon has been a mystery in nuclear physics for over 40 years(2,3). The internal generation of typically six or seven units of angular momentum in each fragment is particularly puzzling for systems that start with zero, or almost zero, spin. There are currently no experimental observations that enable decisive discrimination between the many competing theories for the mechanism that generates the angular momentum(4-12). Nevertheless, the consensus is that excitation of collective vibrational modes generates the intrinsic spin before the nucleus splits (pre-scission). Here we show that there is no significant correlation between the spins of the fragment partners, which leads us to conclude that angular momentum in fission is actually generated after the nucleus splits (post-scission). We present comprehensive data showing that the average spin is strongly mass-dependent, varying in saw-tooth distributions. We observe no notable dependence of fragment spin on the mass or charge of the partner nucleus, confirming the uncorrelated post-scission nature of the spin mechanism. To explain these observations, we propose that the collective motion of nucleons in the ruptured neck of the fissioning system generates two independent torques, analogous to the snapping of an elastic band. A parameterization based on occupation of angular momentum states according to statistical theory describes the full range of experimental data well. This insight into the role of spin in nuclear fission is not only important for the fundamental understanding and theoretical description of fission, but also has consequences for the gamma-ray heating problem in nuclear reactors(13,14), for the study of the structure of neutron-rich isotopes(15,16), and for the synthesis and stability of super-heavy elements(17,18). gamma-ray spectroscopy experiments on the origin of spin in the products of nuclear fission of spin-zero nuclei suggest that the fission fragments acquire their spin after scission, rather than before. |
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Address |
[Wilson, J. N.; Thisse, D.; Lebois, M.; Jovancevic, N.; Adsley, P.; Babo, M.; Chakma, R.; Delafosse, C.; Haefner, G.; Hauschild, K.; Ibrahim, F.; Ljungvall, J.; Lopez-Martens, A.; Lozeva, R.; Matea, I; Nemer, J.; Popovitch, Y.; Qi, L.; Tocabens, G.; Verney, D.] Univ Paris Saclay, IJC Lab, CNRS, IN2P3, Orsay, France, Email: jonathan.wilson@ijclab.in2p3.fr |
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Thesis |
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Publisher |
Nature Research |
Place of Publication |
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Language |
English |
Summary Language |
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Original Title |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0028-0836 |
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Expedition |
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Conference |
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Notes |
WOS:000621583600006 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4717 |
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Author |
Wilkinson, C.; Garcia Soto, A. |
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Title |
Low-ν method with LHC neutrinos |
Type |
Journal Article |
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Year |
2024 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
109 |
Issue |
3 |
Pages |
033010 - 19pp |
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Keywords |
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Abstract |
The Forward Physics Facility (FPF) plans to use neutrinos produced at the Large Hadron Collider to make a variety of measurements at previously unexplored TeV energies. Its primary goals include precision measurements of the neutrino cross section and using the measured neutrino flux both to uncover information about far-forward hadron production and to search for various beyond standard model scenarios. However, these goals have the potential to conflict: Extracting information about the flux or cross section relies upon an assumption about the other. In this paper, we demonstrate that the FPF can use the low-nu method-a technique for constraining the flux shape by isolating neutrino interactions with low energy transfer to the nucleus-to break this degeneracy. We show that the low-nu method is effective for extracting the nu μflux shape, in a model-independent way. We discuss its application for extracting the nu over bar μflux shape but find that this is significantly more model dependent. Finally, we explore the precision to which the nu μflux shape could be constrained at the FPF for a variety of proposed detector options. We find that the precision would be sufficient to discriminate between various realistic flux models. |
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Address |
[Wilkinson, C.] Lawrence Berkeley Natl Lab, Berkeley, CA 94720 USA, Email: cwilkinson@lbl.gov; |
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Publisher |
Amer Physical Soc |
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English |
Summary Language |
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Original Title |
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Series Editor |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2470-0010 |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:001183228500009 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5986 |
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Author |
Wieduwilt, P.; Paschen, B.; Schreeck, H.; Schwenker, B.; Soltau, J.; Ahlburg, P.; Dingfelder, J.; Frey, A.; Gomis, P.; Lutticke, F.; Marinas, C. |
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Title |
Performance of production modules of the Belle II pixel detector in a high-energy particle beam |
Type |
Journal Article |
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Year |
2021 |
Publication |
Nuclear Instruments & Methods in Physics Research A |
Abbreviated Journal |
Nucl. Instrum. Methods Phys. Res. A |
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Volume |
991 |
Issue |
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Pages |
164978 - 15pp |
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Keywords |
DEPFET; DESY testbeam; Pixel detector; Belle II; Vertex detector |
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Abstract |
The Belle II experiment at the Super B factory SuperKEKB, an asymmetric e(+) e(-) collider located in Tsukuba, Japan, is tailored to perform precision B physics measurements. The centre of mass energy of the collisions is equal to the rest mass of the gamma (4S) resonance of m(gamma(4S)) = 10.58 GeV. A high vertex resolution is essential for measuring the decay vertices of B mesons. Typical momenta of the decay products are ranging from a few tens of MeV to a few GeV and multiple scattering has a significant impact on the vertex resolution. The VerteX Detector (VXD) for Belle II is therefore designed to have as little material as possible inside the acceptance region. Especially the innermost two layers, populated by the PiXel Detector (PXD), have to be ultra-thin. The PXD is based on DEpleted P-channel Field Effect Transistors (DEPFETs) with a thickness of only 75 μm. Spatial resolution and hit efficiency of production detector modules were studied in beam tests performed at the DESY test beam facility. The spatial resolution was investigated as a function of the incidence angle and improvements due to charge sharing are demonstrated. The measured module performance is compatible with the requirements for Belle II. |
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Address |
[Paschen, B.; Ahlburg, P.; Dingfelder, J.; Luetticke, F.] Univ Bonn, Phys Inst, Nussallee 12, D-53115 Bonn, Germany, Email: philipp.wieduwilt@phys.uni-goettingen.de; |
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Corporate Author |
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Thesis |
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Publisher |
Elsevier |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0168-9002 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000686054900010 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4941 |
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Author |
Weber, M. et al; Esperante, D. |
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Title |
DONES EVO: Risk mitigation for the IFMIF-DONES facility |
Type |
Journal Article |
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Year |
2024 |
Publication |
Nuclear Materials and Energy |
Abbreviated Journal |
Nucl. Mater. Energy |
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Volume |
38 |
Issue |
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Pages |
101622 - 5pp |
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Keywords |
Signal Transmission Improvement; RF Conditioning Optimisation; Beam Extraction Device; Medical Isotopes Production; Lithium Purification; Critical Components Manufacture |
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Abstract |
The International Fusion Materials Irradiation Facility- DEMO Oriented Neutron Source (IFMIF-DONES) is a scientific infrastructure aimed to provide an intense neutron source for the qualification of materials to be used in future fusion power reactors. Its implementation is critical for the construction of the fusion DEMOnstration Power Plant (DEMO). IFMIF-DONES is a unique facility requiring a broad set of technologies. Although most of the necessary technologies have already been validated, there are still some aspects that introduce risks in the evolution of the project. In order to mitigate these risks, a consortium of companies, with the support of research centres and the funding of the CDTI (Centre for the Development of Industrial Technology and Innovation), has launched the DONES EVO Programme, which comprises six lines of research: center dot Improvement of signal transmission and integrity (planning and integration risks) center dot Optimisation of RF conditioning processes (planning and reliability risks) center dot Development of a reliable beam extraction device (reliability risks) center dot Development of technologies for the production of medical isotopes (reliability risks) center dot Improvement of critical parts of the lithium purification system (safety and reliability risks) center dot Validation of the manufacture of critical components with special materials (reliability risk). DONES EVO will focus on developing the appropriate response to the risks identified in the IFMIFDONES project through research and prototyping around the associated technologies. |
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Address |
[Weber, M.; Ibarra, A.; Maldonado, R.; Podadera, I.] DONES Espana Consortium, IFMIF, Granada, Spain |
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Publisher |
Elsevier |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
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ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:001202783400001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
6075 |
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Author |
Watanabe, H.; Watanabe, Y.X.; Hirayama, Y.; Andreyev, A.N.; Hashimoto, T.; Kondev, F.G.; Lane, G.J.; Litvinov, Y.A.; Liu, J.J.; Miyatake, H.; Moon, J.Y.; Morales, A.I.; Mukai, M.; Nishimura, S.; Niwase, T.; Rosenbusch, M.; Schury, P.; Shi, Y.; Wada, M.; Walker, P.M. |
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Title |
Beta decay of the axially asymmetric ground state of Re-192 |
Type |
Journal Article |
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Year |
2021 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
814 |
Issue |
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Pages |
136088 - 6pp |
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Keywords |
Re-192; beta decay; Axial asymmetry; Shape transition |
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Abstract |
The beta decay of Re-192(75)117, which lies near the boundary between the regions of predicted prolate and oblate deformations, has been investigated using the KEK Isotope Separation System (KISS) in RIKEN Nishina Center. This is the first case in which a low-energy beam of rhenium isotope has been successfully extracted from an argon gas-stopping cell using a laser-ionization technique, following production via multi-nucleon transfer between heavy ions. The ground state of Re-192 has been assigned J(pi) = (0(-)) based on the observed beta feedings and deduced logf t values towards the 0(+) and 2(+) states in Os-192, which is known as a typical gamma-soft nucleus. The shape transition from axial symmetry to axial asymmetry in the Re isotopes is discussed from the viewpoint of single-particle structure using the nuclear Skyrme-Hartree-Fock model. |
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Address |
[Watanabe, H.] Beihang Univ, Sch Phys, Beijing 100191, Peoples R China, Email: hiroshi@ribf.riken.jp |
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Corporate Author |
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Thesis |
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Publisher |
Elsevier |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0370-2693 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000621722300008 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4747 |
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| Permanent link to this record |
