Faculty of Physics University of Warsaw > Events > Seminars > Nuclear Physics Seminar

Nuclear Physics Seminar

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room 1.01, Pasteura 5 at 10:15

Dr hab. inż. Martyna Grodzicka-Kobyłka (NCBJ)

Fotopowielacze krzemowe w detekcji promieniowania gamma i neutronów – zasady działania i zastosowania

Silicon Photomultipliers in Gamma and Neutron Radiation Detection – Principles and Applications

Spektrometria gamma z wykorzystaniem detektorów scyntylacyjnych jest jedną z najważniejszych metod pomiarowych stosowanych w różnych dziedzinach fizyki jądrowej oraz w badaniach z nią związanych. Metoda ta znajduje zastosowanie w podstawowych badaniach fizyki jądrowej, badaniach środowiskowych, medycynie nuklearnej oraz w nowoczesnym wyposażeniu do monitorowania granic. Detektory scyntylacyjne składają się z fotodetektora oraz materiału scyntylacyjnego, który pochłania kwanty gamma, a następnie emituje światło. Wśród najczęściej stosowanych fotodetektorów znajdują się diody PIN, diody lawinowe APD, fotopowielacze próżniowe PMT oraz nowoczesne fotopowielacze krzemowe SiPM. W prezentacji omówione zostaną zasady działania fotopowielaczy krzemowych, ich zalety i ograniczenia, a takżemożliwości ich zastosowania do detekcji światła emitowanego przez scyntylatory w spektrometrii gamma oraz detekcji neutronów. Szczególny nacisk zostanie położony na ich wykorzystanie w fizyce, medycynie isystemach bezpieczeństwa.

Gamma-ray spectrometry using scintillation detectors is one of the most important measurement techniques employed in various fields of nuclear physics and related research. This method finds applications in fundamental nuclear physics studies, environmental monitoring, nuclear medicine, and modern border security systems.
Scintillation detectors consist of a scintillating material, which absorbs gamma quanta and subsequently emits light, and a photodetector responsible for registering this signal. The most commonly used photodetectors include PIN diodes, avalanche photodiodes (APDs), vacuum photomultiplier tubes (PMTs), and modern silicon photomultipliers (SiPMs).
This presentation will cover the operating principles of silicon photomultipliers, their advantages and limitations, as well as their potential applications in detecting light emitted by scintillators in gamma-ray spectrometry and neutron detection. Special emphasis will be placed on their use in physics, medicine, and security systems.

room 1.01, Pasteura 5 at 10:15

dr hab. Aleksander Kusina (Instytut Fizyki Jądrowej PAN, Kraków)

Quark and gluon distributions in nuclei at high energy and their connection with correlated nucleon pairs

We analyze the longitudinal structure of nuclei as described in the context of nuclear parton distribution functions (nPDFs). Such a description uses the language of QCD factorization theorems, in analogy to the parton distributions (PDFs) of free protons. We focus on the high-x region and introduce a novel phenomenological nPDF parametrization inspired by the short range correlation (SRC) models. This allows us for extracting of "traditional" nPDFs but also of the universal effective distribution of quarks and gluons inside the correlated nucleon pairs, and their nucleus-specific fractions.

room 1.01, Pasteura 5 at 10:15

mgr Jan Orliński (ZFJ IFD UW)

Transverse flow of strange hadrons in heavy ion collisions at a beam kinetic energy of a few GeV measured in HADES

The transverse flow of strange hadrons in relativistic heavy ion collisions is predicted to be sensitive to many properties of the hot and dense nuclear matter produced in such interactions. Most importantly, we can get access to the interaction potential between said hadrons and the hadronic medium via model comparisons to the experimental data. Transverse flow can also bear imprint from changes of fundamental properties (effective mass, decay constant) of hadrons immersed in the medium (with the notable example ofsuch a study for charged K mesons) as well as the so-called Hyperon Puzzle in nuclear astrophysics.

In this contribution the basics of transverse flow analysis will be introduced to the audience. We will then move to the preliminary results of the analysis of transverse flow of charged K mesons and the Λ baryons emitted from Ag+Ag collisions at a beam kinetic energy of 1.6 GeV/nucleon. They were measured with the High Acceptance Di-Electron Spectrometer, based in GSI Darmstadt. The results will be presented as maps of v1 and v2 coefficients in the momentum phase-space -- for the Λ baryons no such result has ever been published within this energy regime.

room 1.01, Pasteura 5 at 10:15

dr Magda Zielińska (CEA Paris-Saclay, Université Paris-Saclay, Gif-sur-Yvette, Francja)

Exploring quadrupole and octupole collectivity in 106Cd via unsafe Coulomb excitation

We studied cross-section distributions measured as a function of scattering angle for multiple excited states in 106Cd, populated via inelastic scattering on a 92Mo target. The balance between Coulomb and nuclear interaction in the population of individual states was explored by comparing the experimental γ-ray yields with the predictions obtained with the GOSIA Coulomb-excitation code. We demonstrated that from such an ``unsafe'' Coulomb-excitation measurement it is possible to correctly evaluate reduced transition probabilities between certain low-lying states. In this way, we obtained new information on the collectivity of the presumably oblate structure built on the 0^+_3 state, as well as on the role of octupole correlations in this nucleus. By comparing our observations with the results of previous spectroscopic studies of 106Cd, we were also able to propose a rearrangement of the level scheme including notably K=2 and K=4 structures. These results, as well as remaining puzzles concerning the low-energy part of the 106Cd level scheme, motivated a future high-precision beta-decay study into 106Cd, which has been recently accepted at TRIUMF.

room 1.01, Pasteura 5 at 10:15

mgr Ilaria Michelon (CERN, Uniwersytet Genewski, Szwajcaria)

Beta-decay spectroscopy with beams of laser-polarised nuclei at VITO ISOLDE

Beta-decay spectroscopy is a powerful experimental tool for studying complex phenomena that emerge in exotic neutron-rich nuclei. A novel approach to beta-decay experiments, pioneered by a group from the University of Osaka [1,2], has recently been implemented at the VITO beamline [3] at CERN ISOLDE. The new end station, called DeVITO [4], has been integrated with a laser polarisation setup [3], enabling beta-decay spectroscopy studies with spin-oriented nuclei. This unique combination allows for measurements of beta-particle emission asymmetry in coincidence with gamma rays and/or neutrons, providing a solid foundation for unambiguous spin-parity assignments for states involved in allowed beta transitions [1, 2]. During the seminar, I will present the experimental setup used in the first DeVITO experiment [4], its physics motivation, and preliminary results.

[1] H. Miyatake et al., Phys. Rev. C 67, 014306 (2003).
[2] H. Nishibata et al., Phys. Rev. C 99, 024322 (2019).
[3] M. Kowalska et al., Phys. G: Nucl. Part. Phys. 44, 084005 (2017).
[4] M. Piersa-Siłkowska, M. Madurga, M. Kowalska et al., CERN-INTC-2023-026; INTC-P-662.

room 1.01, Pasteura 5 at 10:15

mgr Przemysław Sękowski (ZFJ IFD i BD Polska sp. z o.o.)

Badanie reakcji protonów na jądrach węgla, azotu i tlenu w stosach tarcz tkankopodobnych oraz nieorganicznych

Zaprezentowane zostaną badania reakcji jądrowych indukowanych wiązką protonową w stosach tarcz wykonanych z materiałów tkankopodobnych oraz nieorganicznych, z uwzględnieniem ich znaczenia w terapii protonowej. Przedstawione wyniki eksperymentalne obejmują reakcje protonów z jądrami węgla, azotu i tlenu, przeprowadzone przy użyciu akceleratora AIC-144.

Omówione zostaną szczegóły układu eksperymentalnego opartego na detektorach LaBr3. Otrzymane rezultaty podkreślają konieczność uwzględnienia efektów jądrowych w procesie planowania terapii protonowej, a także ich potencjał w monitorowaniu skuteczności leczenia.

room 1.01, Pasteura 5 at 10:15

Prof. dr hab. Marek Gaździcki (Jan Kochanowski University, Kielce)

Large charge-symmetry violation in high-energy collisions of atomic nuclei

Strong interactions approximately preserve charge symmetry between up and down quarks, which is a subset of the broader flavour symmetry. In the context of kaon production, if charge symmetry were exact and the ensemble of initial states remained invariant under charge transformations, the production rates of charged and neutral kaons in collisions would be equal.

In this presentation, I will report and discuss results on the relative abundance of charged versus neutral kaons produced in high-energy nucleus-nucleus collisions. The findings reveal a significant, yet unexplained, violation of charge symmetry.

room 1.01, Pasteura 5 at 10:15

dr hab. Marcin Wolter (IFJ PAN)

From Perceptrons to Deep Learning: Nobel Prize for Hopfield and Hinton

Seminar presents the contributions of John Hopfield and Geoffrey Hinton to machine learning, leading to their Nobel Prize win in 2024. The neural network evolution from Rosenblatt's perceptron to deep learning is shown, highlighting milestones like Hopfield networks, backpropagation, and Boltzmann machines.

Seminar includes practical examples of few Machine Learning algorithms, which led to the Nobel Prize in 2024. Slides are prepared in the form of executable iPython notebook and will be available at:
https://github.com/marcinwolter/Seminars/blob/main/Seminarium_2024_12_05.ipynb

*You are encouraged to bring your laptops!*

room 1.01, Pasteura 5 at 10:15

prof. dr hab. Paweł Moskal (Uniwersytet Jagielloński)

First positronium imaging of the human brain using a multi-photon J-PET scanner

The Jagiellonian Positron Emission Tomograph (J-PET) is the first multi-photon PET scanner capable of measuring momentum vectors and polarization of photons originating from the decays of positronium.
J-PET enables imaging of positronium properties in living organisms, the study of discrete symmetries in positronium decays, and studies of the degree of quantum entanglement of photons from electron-positron annihilations.
We will present the first-ever images of the properties of positronium in humans [1,2,3], the most accurate results to date of P, T, CP, and CPT symmetry tests in the decays of positronium atoms [4,5], and the first observation of non-maximal entanglement of photons from positronium annihilation in matter [6].

[1] P. Moskal et al., Nature Reviews Physics 1, 527 (2019).
[2] P. Moskal et al., Science Advances 7, eabh4394 (2021).
[3] P. Moskal et al., Science Advances 10, eadp2890 (2024).
[4] P. Moskal et al., Nature Communication 12, 5658 (2021).
[5] P. Moskal et al., Nature Communication 15, 79 (2024).
[6] P. Moskal et al., arXiv:2407.08574, Science Advances, in review.

room 1.01, Pasteura 5 at 10:15

dr hab. Magdalena Skurzok (Uniwersytet Jagielloński)

Investigation of exotic bound systems with WASA-at-COSY and SIDDHARTA-2 facilities

The study of exotic nuclear matter is currently one of the most popular issues in nuclear physics, both from an experimental and theoretical point of view.
Such exotic nuclear objects include, among others, mesonic atoms and mesic nuclei.
In my presentation, I will show an investigation of eta-mesic nuclei and kaonic atoms with WASA-at-COSY and SIDDHARTA-2 facilities, respectively.

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