Seminarium Fizyki Jądra Atomowego
2006/2007 | 2007/2008 | 2008/2009 | 2009/2010 | 2010/2011 | 2011/2012 | 2012/2013 | 2013/2014 | 2014/2015 | 2015/2016 | 2016/2017 | 2017/2018 | 2018/2019 | 2019/2020 | 2020/2021 | 2021/2022 | 2022/2023 | 2023/2024
2023-11-16 (Czwartek)
Zapraszamy na spotkanie o godzinie 10:15 
prof. dr hab. Jacek Dobaczewski (IFD UW)Nuclear DFT electromagnetic moments in heavy deformed open-shell odd nuclei
About half of the nuclei in nature have odd particle numbers; however, in the past nuclear-DFT applications, odd nuclei were considered much less frequently than even-even ones. As a result, in building the nuclear-DFT functionals, the existing wealth of experimental information on odd systems was virtually unused.
Nuclear electromagnetic moments provide essential information in our understanding of nuclear structure. Observables such as electric quadrupole moments are highly sensitive to collective nuclear phenomena, whereas magnetic dipole moments offer sensitive probes to test our description of microscopic properties such as those of valence nucleons. Although great progress was achieved in the description of electromagnetic properties of light nuclei and experimental trends in certain isotopic chains, a unified and consistent description across the Segré chart of nuclear electromagnetic properties remains an open challenge for nuclear theory.
In our nuclear-DFT methodology, we align angular momenta along the intrinsic axial-symmetry axis with broken spherical and time-reversal symmetries. We fully account for the self-consistent charge, spin, and current polarizations, in particular through the inclusion of the crucial time-odd mean-field components of the functional. Spectroscopic moments are then determined for symmetry-restored wave functions without using effective charges or effective g-factors and compared with available experimental data.
In this talk, I will review the DFT description of nuclear electromagnetic moments and illustrate it with the results obtained in the unpaired odd near doubly magic nuclei [1], heavy paired odd open-shell nuclei [2,3], and in indium [4], silver [5], tin [6], dysprosium [7], and potassium [8] isotopes. In particular, I will discuss different aspects of occupying and mixing the deformed sub-orbitals (Nilsson states) characterised by the projections K of the angular momentum on the intrinsic axial-symmetry axis.
[1] P.L. Sassarini et al., J. Phys G 49 (2022) 11LT01
[2] J. Bonnard et al., Phys. Lett. B 843 (2023) 138014
[3] H. Wibowo et al., to be published
[4] A.R. Vernon et al., Nature 607 (2022) 260; L. Nies et al., Phys. Rev. Lett. 131 (2023) 022502; J. Karthein et al., submitted to Nature Physics; A.R. Vernon et al., to be published
[5] R.P. de Groote et al., submitted to Physics Letters B
[6] T.J. Gray et al., Phys. Lett. B 847 (2023) 138268
[7] J. Dobaczewski et al., to be published
[8] A. Nagpal et al., to be published
Seminarium odbędzie się zdalnie na zoom-ie. Link jest dostępny od 10.00:
https://uw-edu-pl.zoom.us/j/93556002402?pwd=Z1JjYkVvamNHSXVwbFVBMTdUc3Jxdz09
Nuclear electromagnetic moments provide essential information in our understanding of nuclear structure. Observables such as electric quadrupole moments are highly sensitive to collective nuclear phenomena, whereas magnetic dipole moments offer sensitive probes to test our description of microscopic properties such as those of valence nucleons. Although great progress was achieved in the description of electromagnetic properties of light nuclei and experimental trends in certain isotopic chains, a unified and consistent description across the Segré chart of nuclear electromagnetic properties remains an open challenge for nuclear theory.
In our nuclear-DFT methodology, we align angular momenta along the intrinsic axial-symmetry axis with broken spherical and time-reversal symmetries. We fully account for the self-consistent charge, spin, and current polarizations, in particular through the inclusion of the crucial time-odd mean-field components of the functional. Spectroscopic moments are then determined for symmetry-restored wave functions without using effective charges or effective g-factors and compared with available experimental data.
In this talk, I will review the DFT description of nuclear electromagnetic moments and illustrate it with the results obtained in the unpaired odd near doubly magic nuclei [1], heavy paired odd open-shell nuclei [2,3], and in indium [4], silver [5], tin [6], dysprosium [7], and potassium [8] isotopes. In particular, I will discuss different aspects of occupying and mixing the deformed sub-orbitals (Nilsson states) characterised by the projections K of the angular momentum on the intrinsic axial-symmetry axis.
[1] P.L. Sassarini et al., J. Phys G 49 (2022) 11LT01
[2] J. Bonnard et al., Phys. Lett. B 843 (2023) 138014
[3] H. Wibowo et al., to be published
[4] A.R. Vernon et al., Nature 607 (2022) 260; L. Nies et al., Phys. Rev. Lett. 131 (2023) 022502; J. Karthein et al., submitted to Nature Physics; A.R. Vernon et al., to be published
[5] R.P. de Groote et al., submitted to Physics Letters B
[6] T.J. Gray et al., Phys. Lett. B 847 (2023) 138268
[7] J. Dobaczewski et al., to be published
[8] A. Nagpal et al., to be published
Seminarium odbędzie się zdalnie na zoom-ie. Link jest dostępny od 10.00:
https://uw-edu-pl.zoom.us/j/93556002402?pwd=Z1JjYkVvamNHSXVwbFVBMTdUc3Jxdz09
2023-11-09 (Czwartek)
Zapraszamy do sali 1.01, ul. Pasteura 5 o godzinie 10:15
dr hab. Monika Kubkowska (Instytut Fizyki Plazmy i Laserowej Mikrosyntezy, Warszawa)Obecny stan badań nad syntezą jądrową
Najbardziej zaawansowanymi koncepcjami reaktorów termojądrowych są obecnie urządzenia z magnetycznym utrzymaniem plazmy. Przedstawione zostaną zasady działania układów typu tokamak i stellarator, ich wady i zalety. Podczas seminarium zaprezentowane zostaną najnowsze wyniki badań uzyskane na europejskim tokamaku JET znajdującym się w Wielkiej Brytanii. Omówiony zostanie światowy rekord pod względem największej ilości energii wytworzonej w pojedynczym wyładowaniu, generując w sposób ciągły 59 MJ ciepła z reakcji termojądrowych, co jest ponad dwukrotnie więcej niż poprzedni rekord 22 MJ, ustanowiony również na JET w 1997 roku. Ponadto przedstawiona zostanie europejska mapa drogowa badań fuzyjnych wraz z osiągnięciami uzyskanymi na takich urządzeniach jak EAST czy KSTAR oraz stan projektu ITER.
Przedstawiony zostanie również program największego obecnie na świecie stellaratora Wendelstein 7-X znajdującego się w Niemczech, jako alternatywnej koncepcji dla tokamaka. Omówione zostaną najnowsze wyniki badań oraz plany na przyszłość.
Ponadto przedstawiona zostanie koncepcja z inercyjnym utrzymaniem plazmy, a więc z wykorzystaniem laserów, wersja bezpośrednia jak i pośrednia wraz z omówieniem roli tarcz w eksperymentach. Omówione zostaną ostatnie sukcesy osiągnięte na amerykańskim układzie NIF (ang. National Ignition Facility), gdzie energia uzyskana z reakcji wyniosła 3.5 MJ przy energii laserów inicjujących 2.5 MJ.
Przedstawiony zostanie również program największego obecnie na świecie stellaratora Wendelstein 7-X znajdującego się w Niemczech, jako alternatywnej koncepcji dla tokamaka. Omówione zostaną najnowsze wyniki badań oraz plany na przyszłość.
Ponadto przedstawiona zostanie koncepcja z inercyjnym utrzymaniem plazmy, a więc z wykorzystaniem laserów, wersja bezpośrednia jak i pośrednia wraz z omówieniem roli tarcz w eksperymentach. Omówione zostaną ostatnie sukcesy osiągnięte na amerykańskim układzie NIF (ang. National Ignition Facility), gdzie energia uzyskana z reakcji wyniosła 3.5 MJ przy energii laserów inicjujących 2.5 MJ.
2023-10-26 (Czwartek)
Zapraszamy do sali 1.01, ul. Pasteura 5 o godzinie 10:15
dr Natalia Cieplicka-Oryńczak (IFJ PAN, Kraków)“Stretched” states decays studied at CCB IFJ PAN by gamma-particle coincidences
The structure of the “stretched” nuclear excitations is dominated by a single particle-hole component for which both the excited particle (proton or neutron) and the residual hole occupy orbitals with the highest angular momentum in their respective shells, and couple to the highest possible spin which such configuration offers. In light nuclei they appear as high-lying resonances resulting from the p3/2 → d5/2 stretched transitions [1]. Due to the expected low density of other one-particle-one-hole configurations of high angular momenta in this energy region, their structure should be relatively simple comparing to other nuclear excitations in the continuum. This feature makes them attractive as their theoretical analysis could provide clean information about the role of continuum couplings in stretched excitations.
The decays of stretched excitations in light nuclei are expected to be dominated by the proton and neutron emission, however, their decay patterns are poorly known experimentally, thus far. The direct measurement of stretched states decay paths should provide data which can be used as a very demanding test of state-of-the-art theory approaches, like for example, Gamow Shell Model (GSM) [2] which is an adequate tool for the theoretical description of these excitations.
The results of the first experimental studies on the decay of the 21.47-MeV stretched resonance in 13C will be presented. It was investigated in a 13C(p, p′) experiment at 135 MeV proton energy, performed at the Cyclotron Centre Bronowice (CCB) at IFJ PAN in Krakow. The information on the proton and neutron decay branches from the 21.47-MeV state in 13C was obtained by measuring the protons inelastically scattered on a 13C target in coincidence with charged particles from the resonance decay and γ rays from daughter nuclei. In particular, emitted γ rays give a precise knowledge of the feeding to specific states. The detection setup consisting of: i) the KRATTA telescope array, ii) an array of LaBr3 detectors, iii) two clusters of the PARIS scintillator array, and iv) a thick position-sensitive Si detector, was used. The experimental results were compared with theoretical calculations from the GSM, extended to describe stretched resonances in p-shell nuclei. A very good agreement between the measured and predicted properties of the 21.47-MeV state in 13C was obtained.
In a similar measurement at CCB, the decays of stretched resonances in 16O nucleus were also investigated. A triplet of close lying states in 16O, namely at 17.79, 18.98, and 19.80 MeV, was populated. The decay channels via p and α emission were identified by studying the γ rays from daughter nuclei in coincidence with scattered protons. The quantitative information on the decay branching ratios could be extracted from a systematic analysis of the proton-γ matrix. The physical interpretation of the results would largely profit from theoretical calculations, which are not available at the moment. However, the obtained results support the extension of the investigation of the stretched states decays in other nuclei such as 14N, using the present method.
[1] J. Speth, Electric and Magnetic Giant Resonances in Nuclei, World Scientific Publ. Company (1991).
[2] N. Michel, W. Nazarewicz, M. Płoszajczak, T. Vertse, J. Phys. G: Nucl. Part. Phys. 36 (2009) 013101.
The decays of stretched excitations in light nuclei are expected to be dominated by the proton and neutron emission, however, their decay patterns are poorly known experimentally, thus far. The direct measurement of stretched states decay paths should provide data which can be used as a very demanding test of state-of-the-art theory approaches, like for example, Gamow Shell Model (GSM) [2] which is an adequate tool for the theoretical description of these excitations.
The results of the first experimental studies on the decay of the 21.47-MeV stretched resonance in 13C will be presented. It was investigated in a 13C(p, p′) experiment at 135 MeV proton energy, performed at the Cyclotron Centre Bronowice (CCB) at IFJ PAN in Krakow. The information on the proton and neutron decay branches from the 21.47-MeV state in 13C was obtained by measuring the protons inelastically scattered on a 13C target in coincidence with charged particles from the resonance decay and γ rays from daughter nuclei. In particular, emitted γ rays give a precise knowledge of the feeding to specific states. The detection setup consisting of: i) the KRATTA telescope array, ii) an array of LaBr3 detectors, iii) two clusters of the PARIS scintillator array, and iv) a thick position-sensitive Si detector, was used. The experimental results were compared with theoretical calculations from the GSM, extended to describe stretched resonances in p-shell nuclei. A very good agreement between the measured and predicted properties of the 21.47-MeV state in 13C was obtained.
In a similar measurement at CCB, the decays of stretched resonances in 16O nucleus were also investigated. A triplet of close lying states in 16O, namely at 17.79, 18.98, and 19.80 MeV, was populated. The decay channels via p and α emission were identified by studying the γ rays from daughter nuclei in coincidence with scattered protons. The quantitative information on the decay branching ratios could be extracted from a systematic analysis of the proton-γ matrix. The physical interpretation of the results would largely profit from theoretical calculations, which are not available at the moment. However, the obtained results support the extension of the investigation of the stretched states decays in other nuclei such as 14N, using the present method.
[1] J. Speth, Electric and Magnetic Giant Resonances in Nuclei, World Scientific Publ. Company (1991).
[2] N. Michel, W. Nazarewicz, M. Płoszajczak, T. Vertse, J. Phys. G: Nucl. Part. Phys. 36 (2009) 013101.
2023-10-19 (Czwartek)
Zapraszamy do sali 1.01, ul. Pasteura 5 o godzinie 10:15
dr Victor Guadilla Gomez (IFD UW)Gamma spectroscopy at ISOLDE for isospin mirror asymmetry studies
Isospin symmetry between protons and neutrons is an elegant framework of fundamental importance in Nuclear Physics. However, it is known to be an approximate symmetry due to Coulomb interaction and other isospin symmetry-breaking effects. In this seminar, we will present an overview of a recently launched experimental programme at ISOLDE, the radioactive ion beam facility at CERN, focused on isospin mirror asymmetry studies by means of beta decay measurements with gamma spectroscopy techniques.
In particular, we will concentrate on isospin asymmetry in mirror systems along the sd shell, that has been suggested to be an evidence of proton halo structures. This would open an extremely interesting possibility of identifying halo structures by means of beta-decay studies, specially for proton halos, where there is a scarcity of confirmed cases. However, the isospin mirror asymmetries found could also be connected with the incompleteness of the decay data of the neutron rich partners, as will be discussed for the 27Na-27S mirror pair.
In particular, we will concentrate on isospin asymmetry in mirror systems along the sd shell, that has been suggested to be an evidence of proton halo structures. This would open an extremely interesting possibility of identifying halo structures by means of beta-decay studies, specially for proton halos, where there is a scarcity of confirmed cases. However, the isospin mirror asymmetries found could also be connected with the incompleteness of the decay data of the neutron rich partners, as will be discussed for the 27Na-27S mirror pair.
2023-10-12 (Czwartek)
Zapraszamy do sali 1.01, ul. Pasteura 5 o godzinie 10:15
prof. dr hab. Krzysztof Pomorski (UMCS)Low energy nuclear fission dynamics within the 3D Langevin model
A new rapidly convergent shape parametrization based on the Fourier expansion is proposed to model the fission of heavy nuclei. Four collective coordinates are used to characterize the shape of the fissioning system: its elongation, left-right asymmetry, neck size, and nonaxiality. The potential energy landscape is computed within the macroscopic-microscopic approach, on top of which the multi-dimensional Langevin equation is solved to describe the dynamics. The charge equilibration at the scission configuration and the neutron evaporation from the primary fragments after scission is considered. The model gives access to various observables, including fission fragments’ mass, charge, kinetic energy yields, fragment mean N/Z and post-scission neutron multiplicities. The parameters of the model were tuned to reproduce experimental observation from thermal neutron-induced fission of 235U and next used to discuss the transition from the asymmetric to symmetric fission along the Fm isotopic chain as well as to describe the fragment yields produced in fission of excited 250Cf nucleus.
2023-10-05 (Czwartek)
Zapraszamy do sali 1.01, ul. Pasteura 5 o godzinie 10:15
mgr Adam Kubiela (Wydział Fizyki UW)Neutrono-deficytowe izotopy cynku - produkcja, promieniotwórczość dwuprotonowa i inne kanały rozpadu
Obecnie najbardziej neutrono-deficytowym znanym izotopem cynku jest 54Zn. Jest on szczególnie interesujący z punktu widzenia badania promieniotwórczości dwuprotonowej - odkrytego na początku XXI wieku kanału rozpadu, którego mechanizm nadal nie jest w pełni zbadany.
W 2019 roku w ośrodku RIKEN w Japonii przeprowadziliśmy eksperyment, w którym 54Zn oraz dwa mniej egzotyczne izotopy: 55Zn i 56Zn były produkowane w reakcji fragmentacji 78Kr + Be, a ich rozpady były rejestrowane przez detektor OTPC. Zmierzyliśmy przekroje czynne na produkcję tych izotopów oraz zarejestrowaliśmy ich rozpady. Podczas seminarium opiszę ten eksperyment i przedstawię jego wyniki.
W 2019 roku w ośrodku RIKEN w Japonii przeprowadziliśmy eksperyment, w którym 54Zn oraz dwa mniej egzotyczne izotopy: 55Zn i 56Zn były produkowane w reakcji fragmentacji 78Kr + Be, a ich rozpady były rejestrowane przez detektor OTPC. Zmierzyliśmy przekroje czynne na produkcję tych izotopów oraz zarejestrowaliśmy ich rozpady. Podczas seminarium opiszę ten eksperyment i przedstawię jego wyniki.
The most neutron-deficient isotope of zinc known to date is 54Zn. It is particularly interesting in the light of studies of two-proton radioactivity - a decay channel discovered at the beginning of XXI century, still not fully understood.
In 2019 we conducted an experiment at RIKEN facility in Japan, where 54Zn and two less exotic isotopes: 55Zn and 56Zn were produced in a 78Kr + Be fragmentation reaction, and their decays were registered with the Warsaw OTPC detector. Production cross sections of those isotopes were measures and their decays registered. During the seminar I will present and discuss the results of this experiment.
Stron 3 z 3