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Zapraszamy do sali 1.01, ul. Pasteura 5 o godzinie 10:15

mgr Aleksandra Ciemny (ZFJ IFD)

Exotic decay modes of medium-mass proton drip-line nuclei

High energy available in beta decay of nuclei lying far to the left from the stability path leads to population of highly excited states in the daughter nuclei. This, combined with decreasing charged-particle separation energies in the daughter nuclei, opens windows for a variety of decay modes with beta-delayed (multi-) particle emission. The study of these decay channels provide a unique tool for gaining an insight and understanding on the nuclear structure in this region, given their competitiveness against the de-excitation via gamma radiation. Moreover, decay data of these nuclei can provide an important input for the astrophysical rp-process modeling and thus understanding the abundance of elements in the universe.

During the previous decade, several experiments studying decays of exotic medium-mass neutron-deficient isotopes were performed using Warsaw Optical Time Projection Chamber. I will present results of two of them. In the first experiment, conducted at the National Superconducting Cyclotron Laboratory at Michigan State University several Ge and Zn isotopes were produced and investigated. Among the outcomes are the first identification of 59Ge, the first information on beta decay properties of 60Ge and the measurement of the cross-section for the most neutron-deficient germanium isotopes. The two most neutron-deficient silicon isotopes known to date, 22,23Si, were investigated in the second experiment, performed using the MARS spectrometer at the Cyclotron Institute of Texas A&M University. The data collected allowed confirmation of all known decay channels for both isotopes, as well as for the extension of the known energy spectra for the delayed protons to lower energies and the identification of new decay branches in 23Si.

Zapraszamy na spotkanie o godzinie 10:15

prof. Anu Kankainen (University of Jyväskylä, Finlandia)

Studies for nuclear structure and astrophysics with the JYFLTRAP Penning trap

The JYFLTRAP double Penning trap mass spectrometer at the Ion Guide Isotope Separator On-Line (IGISOL) facility offers excellent possibilities for high-precision mass measurements relevant both for nuclear structure and astrophysics. Around 400 atomic masses, including around 50 isomeric states, have been measured with JYFLTRAP. Ions of interest are typically produced via proton-induced fission on uranium or fusion-evaporation reactions using beams delivered from the K-130 cyclotron at the JYFL Accelerator Laboratory. Recently, multinucleon-transfer reactions have also been tested at IGISOL. In addition to mass measurements, JYFLTRAP has been used as a high-resolution mass separator for decay spectroscopy experiments as well as an ion counter for fission yield studies. In this presentation, I will give an overview of recent activities with selected highlights from JYFLTRAP at IGISOL.

Seminarium odbędzie się zdalnie na zoom-ie. Link jest dostępny od 10.00:
https://us02web.zoom.us/j/81630676206?pwd=TGhheWUwR3lLOFdtd0NFZW1VdnMyZz09

Zapraszamy do sali 1.01, ul. Pasteura 5 o godzinie 10:15

dr Urszula Kaźmierczak (ŚLCJ UW)

Pracownia radiobiologiczna w ŚLCJ UW

Radiobiologia jest interdyscyplinarną dziedziną nauki, z pogranicza biologii, fizyki jądrowej i medycyny, zajmującą się badaniem wpływu promieniowania jonizującego na organizmy żywe. Wykorzystanie wiedzy z wyżej wymienionych dyscyplin pozwala na osiągnięcie różnych, złożonych celów badawczych.
Układ do badań radiobiologicznych na wiązce cyklotronu U-200P powstał w ŚLCJ UW w 2006 roku. Jednak materiał biologiczny napromieniany w ŚLCJ był od początku przygotowywany oraz analizowany po napromienieniu w Instytucie Chemii i Techniki Jądrowej w Warszawie. W 2018 roku rozpoczęto prace nad otwarciem nowoczesnej pracowni radiobiologicznej na terenie ŚLCJ. Dzięki temu wyeliminowano konieczność transportu komórek na duże odległości oraz umożliwiono śledzenie zmian w materiale biologicznym powstałych bezpośrednio po jego napromienieniu.
Podczas seminarium przedstawiona zostanie pracownia radiobiologiczna ŚLCJ oraz już przeprowadzone w niej wstępne badania odpowiedzi biologicznej komórek na promieniowanie.

Zapraszamy do sali 1.01, ul. Pasteura 5 o godzinie 10:15

prof. dr hab Paweł Moskal (Wydział Fizyki, Astronomii i Informatyki Stosowanej Uniwersytetu Jagiellońskiego w Krakowie)

Positronium imaging with the J-PET tomograph

The Jagiellonian Positron Emission Tomograph (J-PET) is the first PET scanner based on plastic scintillators.
In combination with the newly invented_ positronium imaging _method, it enables the study of discrete symmetries in positronium decays and the study and imaging of positronium properties inside living organisms.
In the seminar talk, we will present the latest results of P, T, CP, and CPT symmetry studies (Nature Communication 12, 5658 (2021)), as well as _in vitro_ positronium images of healthy and cancer tissues (Science Advances 7, eabh4394 (2021)). We will also present preliminary results from the first-ever_ in vivo_ _positronium imaging _of the human brain using a portable and modular J-PET prototype at the Medical University of Warsaw in March 2022.

Zapraszamy do sali 1.01, ul. Pasteura 5 o godzinie 10:15

dr Marcin Kuźniak (Associate Professor, AstroCeNT: Particle Astrophysics Science and Technology Centre, Warsaw, Poland)

Poszukiwanie ciemnej materii przy pomocy detektorów ciekło-argonowych

Większość materii we Wszechświecie to tzw. ciemna materia, która stanowi 23% gęstości energii (podczas gdy zwykła materia stanowi zaledwie 4,6%, a pozostałą część przypisuje się ciemnej energii). Jednak natura ciemnej materii pozostaje wciąż nieznana, a jej pochodzenie jest obecnie jednym z najważniejszych pytań w fizyce.
Poszukiwania oddziaływań cząstek ciemnej materii (WIMP) ze zwykłą materię prowadzone są przy pomocy dużych detektorów umieszczonych w podziemnych laboratoriach (takich jak SNOLAB w Kanadzie czy Gran Sasso we Włoszech), w celu stłumienia tła pochodzącego od promieniami kosmicznych. Jedna z najbardziej obecnie obiecujących technologii detekcji opiera się na wykorzystaniu dużej masy ciekłego argonu lub ksenonu jako tarczy w detektorze.
Zaprezentowany zostanie stan poszukiwań ciemnej materii, ze szczególnym uwzględnieniem detektorów opartych na ciekłym argonie: aktualnie działający eksperyment DEAP-3600, budowany DarkSide-20k i planowany detektor ARGO, który będzie zawierał ok. 400 ton ciekłego argonu i pozwoli osiągnąć najwyższą osiągalną czułość na oddziaływania WIMP.

Zapraszamy na spotkanie o godzinie 10:15

prof. José Enrique García-Ramos (Facultad de Ciencias Experimentales, Universidad de Huelva, Spain)

On the nature of the shape coexistence and the quantum phase transition phenomena in the zirconium and lead region

The shape coexistence phenomenon is related with the presence in the same energy region of eigenstates with different deformations. The lead region is considered as a paradigm for shape coexistence and several decades of experimental effort have supported this believe. In particular, long chains of the Pb, Hg, Pt and Po isotopes have been measured and a rich experimental body of data concerning, excitation energies, electromagnetic transition rates, radii, magnetic g-factors, alpha-hindrance factors and Coulomb excitation reactions, has been obtained.
In the case of Pb and Hg, the presence of intruder states is self-evident inspecting the parabolic energy systematics of the intruder states. However, in the case of Pt and Po, the presence and influence of intruder states is not obvious.
On the other hand, the concept of quantum phase transition (QPT), which has gained a lot of attention in nuclear physics, among other fields, during the last twenty years, appears when the Hamiltonian that describes the quantum system can be written in terms of two pieces, at least, each one with a given symmetry, and a Hamiltonian parameter, i.e., a control parameter, allows to pass from one to the other symmetry. This passing supposes a sudden change in a control parameter and a discontinuity in the ground-state energy or in some of its derivatives.
The rare-earth region around N=90 is very well known for containing examples of QPT's, in particular, the even-even isotope chains of Nd, Sm, or Gd show first order QPTs. In other regions, as in Ba or Ru even-even isotope chains, second order QPTs appear.
The goal of this seminar is to try to clarify the connection between shape coexistence and QPT, two seemingly unrelated phenomena, but that, once studied in deep, share common aspects: the rapid change in the ground state structure when going through an isotope chain or the presence in the mean-field energy surface of several minima. To illustrate the similarities and differences between both phenomena, we will focus on the Zr and Sr region which is known for the rapid change of the ground state deformation and also for the presence of intruder states coming from two-particle two-hole excitations across Z=40 shell closure. We will also pay attention to the lead region.

[1] J.E. Garcia-Ramos, K. Heyde, "The Pt isotopes: Comparing the Interacting Boson Model with configuration mixing and the extended consistent-Q formalism", Nuclear Physics A 825, 39-70 (2009).
[2] J.E. Garcia-Ramos, K. Heyde, "Nuclear shape coexistence: A study of the even-even Hg isotopes using the interacting boson model with configuration mixing", Physical Review C, 89, 014306-24pp (2014).
[3] J.E. Garcia-Ramos, K. Heyde, "Quest of shape coexistence in Zr isotopes", Physical Review C 100, 044315-25p (2019).
[4] J.E. Garcia-Ramos, K. Heyde, "Subtle connection between shape coexistence and quantum phase transition: The Zr case", Physical Review C 102, 054333-16p (2020).
[5] E. Maya-Barbecho and J.E. Garcia-Ramos, "Shape coexistence in Sr isotopes", Physical Review C (in press).

Seminarium odbędzie się zdalnie na zoom-ie. Link jest dostępny od 10.00:
https://us02web.zoom.us/j/81630676206?pwd=TGhheWUwR3lLOFdtd0NFZW1VdnMyZz09

Zapraszamy na spotkanie o godzinie 10:15

prof. Dario Vretenar (Uniwersytet w Zagrzebiu, Chorwacja)

Induced fission dynamics

A microscopic description of low-energy induced fission dynamics is either based on the time-dependent generator coordinate method (TDGCM), or on the framework of time-dependent density functional theory (TDDFT). We review recent applications of TDGCM in the Gaussian overlap approximation (GOA), based on microscopic energy density functionals, to selected topics of fission dynamics: finite-temperature effects, collective inertia, dynamic pairing degrees of freedom, and dissipation. A consistent microscopic framework is introduced, that combines TDGCM+GOA and TDDFT to describe both the adiabatic evolution and dissipative dynamics. We also present a new TDDFT study of cluster formation in the neck region during the scission phase of fission.

J. Zhao, T. Nikšić, D. Vretenar, and S.-G. Zhou, Phys. Rev. C 99, 014618 (2019).
J. Zhao, J. Xiang, Z.-P. Li, T. Nikšić, D. Vretenar, and S.-G. Zhou, Phys. Rev. C 99, 054613 (2019).
J. Zhao, T. Nikšić, D. Vretenar, and S.-G. Zhou, Phys. Rev. C 101, 064605 (2020).
J. Zhao, T. Nikšić, and D. Vretenar, Phys. Rev. C 104, 044612 (2021).
Z. X. Ren, J. Zhao, D. Vretenar, T. Nikšić, P. W. Zhao, J. Meng, arXiv:2111.15025
Z. X. Ren, D. Vretenar, T. Nikšić, P. W. Zhao, J. Zhao, J. Meng, arXiv:2111.11075

Seminarium odbędzie się zdalnie na zoom-ie. Link jest dostępny od 10.00:
https://us02web.zoom.us/j/81630676206?pwd=TGhheWUwR3lLOFdtd0NFZW1VdnMyZz09

Zapraszamy na spotkanie o godzinie 10:15

dr Alvalo Tolosa-Delgado (Jyvaskyla University)

High accuracy neutron emission measurements of nuclei around 78Ni for nuclear astrophysics

Beta-delayed neutron emission is the dominant decay mode of very neutron-rich nuclei produced during the rapid neutron capture process (r-process). This form of decay plays a key role determining the r-process path and affects the final abundance distribution in a complex way, shifting the distribution to lower masses, while it provides neutrons for late captures after the freeze-out with the opposite effect. Thus, a good knowledge of beta-delayed neutron emission probabilities and beta-decay half-lives is required for a meaningful comparison of r-process simulations with the observed elemental abundances. Furthermore, some of the nuclei involved in the r-process can emit more than one neutron in the decay. Our current understanding of the beta-delayed multiple neutron emission is incomplete because the scarcity of experimental data. Additionally, neutron emission probabilities are sensitive to the nuclear wave function and can be used as a test of nuclear structure studies.

With these ideas in mind the Beta-delayed neutrons at RIKEN (BRIKEN) Collaboration has set up a powerful detection system based on a state-on-the-art instrumentation, namely an implanted-ion and decay detector AIDA and a large neutron counter. The setup exploits the very intense secondary radioactive beams available at the end of the in-flight separator BigRIPS and ZeroDegree spectrometers, hosted in the RIKEN Nishina Center. The astrophysical impact of new experimental values for 38 nuclei around the doubly-magic nucleus obtained during the RIBF127 experiment will be shown.

Seminarium odbędzie się zdalnie na zoom-ie. Link jest dostępny od 10.00:
https://us02web.zoom.us/j/81630676206?pwd=TGhheWUwR3lLOFdtd0NFZW1VdnMyZz09

Zapraszamy na spotkanie o godzinie 10:15

dr Magdalena Zielińska (IRFU,DPhN, CEA Saclay, Université Paris-Saclay)

AGATA wraca do Legnaro

AGATA - Advanced GAmma Tracking Array - to najnowocześniejszy w Europie spektrometrpromieniowania gamma, budowany we współpracy dwunastu państw. Po trwającej siedem lat kampaniieksperymentalnej w GANIL, AGATA powraca do Legnaro, gdzie w 2010 przeprowadzono pierwszepomiary na wiązce ciężkich jonów z wykorzystaniem detektorów tego układu, w tym eksperymentwzbudzenia kulombowskiego 42Ca zaproponowany przez fizyków z Warszawy i Krakowa. Przedstawię aktualny stan przygotowań do kampanii eksperymentalnej oraz założenia i cele pomiarów, które zostaną przeprowadzone w obecnym roku, ze szczególnym uwzględnieniem projektów, w które są silniezaangażowani polscy fizycy.

Seminarium odbędzie się zdalnie na zoom-ie. Link jest dostępny od 10.00:
https://us02web.zoom.us/j/81630676206?pwd=TGhheWUwR3lLOFdtd0NFZW1VdnMyZz09

Zapraszamy na spotkanie o godzinie 10:15

dr Rui Han (Uniwersytet w Jyväskylä, Finlandia)

cission configuration in self-consistent calculations with neck constraints

The calculations of the potential-energy surface are essential in theoretical description of the fissionprocess. In the constrained self-consistent approach, the smooth evolution of the nuclear shape is describedfrom the ground state until a very elongated one with a narrow neck. In all microscopic calculations, therupture of the neck at scission is associate with a substantial change of nuclear matter density distribution andrapid energy decrease. It will be showed that there is no discontinuity of the potential-energy surface at scissionwhen multi-constrained calculations are applied with the neck constraint. An early rupture of the neck at lowerquadrupole and octupole moments is discussed as competitive with the conventional fission path. The neckproperties in the scission configuration are also discussed.

Seminarium odbędzie się zdalnie na zoom-ie. Link dostępny od 10.00:
https://us02web.zoom.us/j/81630676206?pwd=TGhheWUwR3lLOFdtd0NFZW1VdnMyZz09

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