Seminarium Fizyki Jądra Atomowego
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2020-11-26 (Czwartek)
Zapraszamy na spotkanie o godzinie 10:15 
prof. Costel Petrache (Uniwersytet Paris-Saclay, Francja)Chirality and wobbling in nuclei: new achievements and perspectives
The breaking of symmetries in quantum systems is one of the key issues in nuclear physics. In particular, the spontaneous symmetry breaking in rotating nuclei leads to exotic collective modes, like the chiral and wobbling motions, which have been intensively studied in recent years. Chiral bands in even-even nuclei, which were taught to be un-favoured energetically, unstable against 3D rotation and difficult to observe, have been instead identified very recently in 136Nd. Multiple chiral bands have been also identified in the neighbouring 135,137Nd nuclei, and pseudospin-chiral quartet bands in the presence of octupole correlations have been identified in 131Ba. These new experimental results triggered many theoretical developments and extensions of the previous models, which are now able to describe complex band structures resulting from chirality-parity violation in triaxial nuclei with reflection asymmetry. An overview of the latest experimental results and theoretical developments will be presented.
The wobbling motion is another topic related to triaxial nuclei, with new results and theoretical developments under intense current debate. The first evidence of wobbling bands built on two-quasiparticle configurations has been recently found in 130Ba. Several low-spin bands in odd-even nuclei have been interpreted as wobbling bands with transverse or longitudinal coupling between the odd nucleon and the triaxial core, but the experimental evidence on the collective transitions connecting the wobbling partners is often contradictory. Recent theoretical works revealed the inadequacy of the wobbling interpretation of these low-spin bands, which in reality are tilted precession (TiP) bands. The recently published results and their interpretation will be discussed.
Seminarium on-line na platformie zoom:
https://us02web.zoom.us/j/86759935850?pwd=ejZhaHBjUTNncVVDZFJTRnVaYW9MQT09
ID: 867 5993 5850
Passcode: 909432
The wobbling motion is another topic related to triaxial nuclei, with new results and theoretical developments under intense current debate. The first evidence of wobbling bands built on two-quasiparticle configurations has been recently found in 130Ba. Several low-spin bands in odd-even nuclei have been interpreted as wobbling bands with transverse or longitudinal coupling between the odd nucleon and the triaxial core, but the experimental evidence on the collective transitions connecting the wobbling partners is often contradictory. Recent theoretical works revealed the inadequacy of the wobbling interpretation of these low-spin bands, which in reality are tilted precession (TiP) bands. The recently published results and their interpretation will be discussed.
Seminarium on-line na platformie zoom:
https://us02web.zoom.us/j/86759935850?pwd=ejZhaHBjUTNncVVDZFJTRnVaYW9MQT09
ID: 867 5993 5850
Passcode: 909432
2020-11-19 (Czwartek)
Zapraszamy na spotkanie o godzinie 10:15
dr. Agnieszka Trzcińska (ŚLCJ UW)Rozkład wysokości barier na fuzję w systemach 24Mg + 90,92Zr - wpływ dyssypacji
Pomiary rozkładów barier na fuzję i próba zrozumienia co je determinuje to wieloletni projekt naszej grupy. Wyznaczenie rozkładu barier w systemach 24Mg + 90,92Zr jest kolejnym krokiem w jego realizacji. Celem eksperymentu było potwierdzenie hipotezy (wynikającej z wcześniejszych pomiarów), że w układach z dużą liczbą poziomów niekolektywnych dyssypacja znacząco wpływa na kształt rozkładu barier. Dyssypacja w tym przypadku wynika ze sprzężeń do wielu poziomów jednocząstkowych.
Pomiar był przeprowadzony w LNS w Katanii z wykorzystaniem wielodektorowego układu CHIMERA, na wiązce 24Mg o energii 68-88 MeV przyspieszonej przez tamtejszy tandem.
Wyniki eksperymentu wydają się potwierdzać postawioną tezę. Są także zgodne obliczeniami wykonami wg modelu „CC+RMT” – modelu łączącego w sobie metodę Kanałów Sprzężonych (Coupled Channels) i teorię macierzy losowych (Random Matrix Theory). Model ten pozwala uwzględnić sprzężenia do licznych poziomów jednocząstkowych.
Seminarium on-line na platformie zoom:
https://us02web.zoom.us/j/86759935850?pwd=ejZhaHBjUTNncVVDZFJTRnVaYW9MQT09
ID: 867 5993 5850
Passcode: 909432
Pomiar był przeprowadzony w LNS w Katanii z wykorzystaniem wielodektorowego układu CHIMERA, na wiązce 24Mg o energii 68-88 MeV przyspieszonej przez tamtejszy tandem.
Wyniki eksperymentu wydają się potwierdzać postawioną tezę. Są także zgodne obliczeniami wykonami wg modelu „CC+RMT” – modelu łączącego w sobie metodę Kanałów Sprzężonych (Coupled Channels) i teorię macierzy losowych (Random Matrix Theory). Model ten pozwala uwzględnić sprzężenia do licznych poziomów jednocząstkowych.
Seminarium on-line na platformie zoom:
https://us02web.zoom.us/j/86759935850?pwd=ejZhaHBjUTNncVVDZFJTRnVaYW9MQT09
ID: 867 5993 5850
Passcode: 909432
2020-11-12 (Czwartek)
Zapraszamy na spotkanie o godzinie 10:15
(IFD UW)Seminarium nie odbędzie się
Szanowni Państwo,
zgodnie z decyzją władz Wydziału Fizyki UW, w czwartek 12 listopada zajęcia odbywają się według harmonogramu środowego (patrz niżej). Dlatego w czwartek, 12 listopada 2020 seminarium ZFJ nie odbędzie się. Następne seminarium będzie 19 listopada. Ogłoszenie wkrótce.
K. Rusek, J. Skalski, W. Urban
-------- Wiadomość oryginalna --------
Temat: Plan środowy w czwartek 12.11 // Wednesday schedule on Thu, Nov 12
Data: 2020-11-06 09:37
Od: Krzysztof Turzyński
Do: pracownicy-nauczyciele@fuw.edu.pl, doktoranci@fuw.edu.pl
Szanowni Państwo,
Uprzejmie przypominam, że w czwartek 12 listopada zajęcia odbywają się według harmonogramu środowego.
Pozdrawiam serdecznie,
Krzysztof Turzyński
prodziekan ds. studenckich
***
Dear Colleagues,
I would like to remind you that on Thursday, November 12, classes are held according to the Wednesday schedule.
Best regards,
Krzysztof Turzyński
Deputy Dean for Student Affairs
zgodnie z decyzją władz Wydziału Fizyki UW, w czwartek 12 listopada zajęcia odbywają się według harmonogramu środowego (patrz niżej). Dlatego w czwartek, 12 listopada 2020 seminarium ZFJ nie odbędzie się. Następne seminarium będzie 19 listopada. Ogłoszenie wkrótce.
K. Rusek, J. Skalski, W. Urban
-------- Wiadomość oryginalna --------
Temat: Plan środowy w czwartek 12.11 // Wednesday schedule on Thu, Nov 12
Data: 2020-11-06 09:37
Od: Krzysztof Turzyński
Do: pracownicy-nauczyciele@fuw.edu.pl, doktoranci@fuw.edu.pl
Szanowni Państwo,
Uprzejmie przypominam, że w czwartek 12 listopada zajęcia odbywają się według harmonogramu środowego.
Pozdrawiam serdecznie,
Krzysztof Turzyński
prodziekan ds. studenckich
***
Dear Colleagues,
I would like to remind you that on Thursday, November 12, classes are held according to the Wednesday schedule.
Best regards,
Krzysztof Turzyński
Deputy Dean for Student Affairs
2020-11-05 (Czwartek)
Zapraszamy na spotkanie o godzinie 10:00
dr Szymon Puławski (Uniwersytet Śląski, Katowice)Badanie relatywistycznych zderzeń hadronów i jonów przy wykorzystaniu detektora NA61/SHINE działającego przy akceleratorze SPS w CERN
Głównym celem programu fizycznego eksperymentu NA61/SHINE jest badanie diagramu fazowego silnie oddziałującej materii w szerokim zakresie energii dostępnej przy wykorzystaniu akceleratora SPS w CERN. Jednym z podstawowych zadań eksperymentu jest badanie własności przejścia fazowego: gaz hadronowy - plazma kwarkowo-gluonowa. W ramach prezentowanego wystąpienia przedstawione zostaną cele naukowe eksperymentu, najnowsze rezultaty związane z badaniem wspomnianego przejścia fazowego, wyniki pomiarów produkcji dziwności w zderzeniach p+p oraz dalsze plany pracy eksperymentu.
Seminarium on-line na platformie zoom:
https://us02web.zoom.us/j/86759935850?pwd=ejZhaHBjUTNncVVDZFJTRnVaYW9MQT09
ID: 867 5993 5850
Passcode: 909432
Seminarium on-line na platformie zoom:
https://us02web.zoom.us/j/86759935850?pwd=ejZhaHBjUTNncVVDZFJTRnVaYW9MQT09
ID: 867 5993 5850
Passcode: 909432
2020-10-29 (Czwartek)
Zapraszamy na spotkanie o godzinie 10:00
(IFD UW)Jest odwołane
Szanowni Państwo,
mimo wielu usiłowań, nie udało się znaleźć prelegenta na jutrzejsze seminarium. W związku z tym seminarium 29.10.2020 jest odwołane. Następne seminarium odbędzie się planowo, w dniu 05.11.2020. Tytuł i streszczenie podamy wkrótce.
Z wyrazami szacunku,
K. Rusek, J. Skalski, W.Urban
mimo wielu usiłowań, nie udało się znaleźć prelegenta na jutrzejsze seminarium. W związku z tym seminarium 29.10.2020 jest odwołane. Następne seminarium odbędzie się planowo, w dniu 05.11.2020. Tytuł i streszczenie podamy wkrótce.
Z wyrazami szacunku,
K. Rusek, J. Skalski, W.Urban
2020-10-22 (Czwartek)
Zapraszamy na spotkanie o godzinie 10:00
mgr. Eliana Masha (Università degli studi di Milano and INFN, Sezione di Milano, Milano, Italy)Underground nuclear astrophysics and the study of 22Ne(α; γ)26Mg and 20Ne(p; γ)21Na reaction at LUNA
The cross sections of nuclear reactions that take place in different astrophysical scenariosare crucial ingredients to understand the synthesis of the elements and energy generation. In stars, nuclear reactions occur at energies well below the Coulomb barrier. Therefore, theircross sections are often too small and very difficult to be measured in laboratories at theEarth’s surface, where the signal would be covered by the cosmic-ray induced background. An effective solution to suppress the cosmic-ray induced background is to perform experiments in underground laboratories. The extremely low background reached at the Laboratory for Underground Nuclear Astrophysics (LUNA) located deep underground at Gran Sasso National Laboratories (Italy) allows to measure nuclear cross sections directly at the energies of astrophysical interest. In the last 30 years, many crucial reactions involved in different astrophysical scenarios have been measured at LUNA.
The presentation will provide an overview of the measurements of 22Ne(α; γ)26Mg and20Ne(p; γ)21Na reactions ongoing at LUNA. The 22Ne(α; γ)26Mg reaction competes with the22Ne(α; n)25Mg reaction which is the main source of neutrons for the s-process in low-massAsymptotic Giant Branch (AGB) and massive stars. Moreover, it has been found that theuncertainty of the 22Ne(α; γ)26Mg reaction rate affects also the nucleosynthesis of isotopesbetween 26Mg and 31P in intermediate-mass AGB stars. The 22Ne(α; γ)26Mg reaction rate is influenced by the 395 keV resonance which has been studied only indirectly leading to a widerange of possible values for its resonance strength (10-15 - 10-9 eV). For the first time LUNAmeasured directly the resonance at 395 keV. The experimental details and preliminary resultswill be shown, together with their possible impact on the 22Ne(α; γ)26Mg reaction rate.The 20Ne(p; γ)21Na is the first reaction of the NeNa cycle and having the slowest reaction rate it controls the speed of the entire cycle. The rate of the 20Ne(p; γ)21Na reaction, depending on the temperature, is dominated by the high energy tail of a sub-threshold state at ER = 6.7 keV, a direct capture component and a narrow resonance at ER = 366 keV. The first campaign,dedicated to the study of the 366 keV resonance is ongoing at LUNA. The experimentalapproach as well as some "online" analysis will be shown.
Seminarium on-line na platformie zoom:
https://us02web.zoom.us/j/86759935850?pwd=ejZhaHBjUTNncVVDZFJTRnVaYW9MQT09
ID: 867 5993 5850
Passcode: 909432
The presentation will provide an overview of the measurements of 22Ne(α; γ)26Mg and20Ne(p; γ)21Na reactions ongoing at LUNA. The 22Ne(α; γ)26Mg reaction competes with the22Ne(α; n)25Mg reaction which is the main source of neutrons for the s-process in low-massAsymptotic Giant Branch (AGB) and massive stars. Moreover, it has been found that theuncertainty of the 22Ne(α; γ)26Mg reaction rate affects also the nucleosynthesis of isotopesbetween 26Mg and 31P in intermediate-mass AGB stars. The 22Ne(α; γ)26Mg reaction rate is influenced by the 395 keV resonance which has been studied only indirectly leading to a widerange of possible values for its resonance strength (10-15 - 10-9 eV). For the first time LUNAmeasured directly the resonance at 395 keV. The experimental details and preliminary resultswill be shown, together with their possible impact on the 22Ne(α; γ)26Mg reaction rate.The 20Ne(p; γ)21Na is the first reaction of the NeNa cycle and having the slowest reaction rate it controls the speed of the entire cycle. The rate of the 20Ne(p; γ)21Na reaction, depending on the temperature, is dominated by the high energy tail of a sub-threshold state at ER = 6.7 keV, a direct capture component and a narrow resonance at ER = 366 keV. The first campaign,dedicated to the study of the 366 keV resonance is ongoing at LUNA. The experimentalapproach as well as some "online" analysis will be shown.
Seminarium on-line na platformie zoom:
https://us02web.zoom.us/j/86759935850?pwd=ejZhaHBjUTNncVVDZFJTRnVaYW9MQT09
ID: 867 5993 5850
Passcode: 909432
2020-10-15 (Czwartek)
Zapraszamy na spotkanie o godzinie 10:00
Dr Giulia Colucci (ŚLCJ UW)A fast ionization chamber for the detection of fusion-evaporation residues produced by the exotic beams of SPES: design, tests and first experiment
Szanowni Państwo,
Rozpoczynamy cotygodniowe spotkania „Seminarium Fizyki Jądra Atomowego”.
Zgodnie z poleceniem władz UW i Wydziału Fizyki, zajęcia te będą odbywały się w trybie „online” za pomocą programu „zoom.us”. Link (ten sam dla wszystkich spotkań), aktywny w każdy czwartek w godz. od 10.00 do 12.00 to:
https://us02web.zoom.us/j/86759935850?pwd=ejZhaHBjUTNncVVDZFJTRnVaYW9MQT09
ID: 867 5993 5850
Passcode: 909432
Abstract: Heavy-ion fusion at near-barrier energies is a complex phenomenon. The availability of radioactive beams has opened new possibilities to investigate these reactions - the very neutron-rich beams of the SPES facility [1] at relatively low intensities may enable the study of near- and sub-barrier fusion to exotic systems. However, the use of RIBs is often very challenging because of the low available intensities and the forward focusing of the fusion evaporation residues (ER). Thus, applications of radioactive beams require detection systems with very high efficiency and detectors that avoid unnecessary energy straggling and angular dispersion and assure fast response.
A new set-up for fusion cross section measurements, especially designed for the low intensity beams which will be delivered by the SPES facility, has been developed and installed and it is presently in use at the National Laboratories of Legnaro (LNL), in its initial operation phase. The set-up is inspired on a similar one built at Oak Ridge [2] some years ago, with a significant improvement due to the use of a very fast ionization chamber (IC). This new fast IC is designed to ensure a high-counting-rate particle identification for fusion studies involving exotic beams up to 105 pps. Indeed, the IC will be placed at 0° with respect to the beam direction without filtering out the beam ions in any way. To reduce the response time of the ionization chamber, a design using a series of tilted electrodes has been adopted [3]. The aim is to be able to detect and identify fusion events within a counting rate up to 100-200 kHz. The set-up already existing at LNL for fusion measurements (based on the electrostatic beam deflector) has been upgraded by using the new IC and will remain in use for experiments with high-intensity stable (and upcoming exotic) beams. Several tests with stable beams have been performed to optimize the performance of the Fast IC [4]. The detector has been also employed for the experimental study of sub-barrier fusion in the 36S + 50Ti, 51V systems [5]. Aim of the experiment was to investigate possible effects of the non-zero spin of 51V ground state on the sub-barrier excitation function and on the shape of the barrier distribution. The fundamental concepts of a IC with fast response will be presented, the results of the in-beam tests and experiment performed will be showed in this seminar.
REFERENCES
[1] The SPES project: technical and scientific reports http://www.lnl.infn.it/ spes/
[2] D. Shapira et al., Nucl. Instr. Meth. Phys. Res. A 551, 330 (2005)
[3] K.Y. Chae et al., Nucl. Instr. Meth. Phys. Res. A 751, 6 (2014)
[4] G.Colucci et al., Acta Phys. Pol. B 50, 573 (2019)
[5] G. Colucci at al., Eur. Phys. J. A 55, 111 (2019)
Rozpoczynamy cotygodniowe spotkania „Seminarium Fizyki Jądra Atomowego”.
Zgodnie z poleceniem władz UW i Wydziału Fizyki, zajęcia te będą odbywały się w trybie „online” za pomocą programu „zoom.us”. Link (ten sam dla wszystkich spotkań), aktywny w każdy czwartek w godz. od 10.00 do 12.00 to:
https://us02web.zoom.us/j/86759935850?pwd=ejZhaHBjUTNncVVDZFJTRnVaYW9MQT09
ID: 867 5993 5850
Passcode: 909432
Abstract: Heavy-ion fusion at near-barrier energies is a complex phenomenon. The availability of radioactive beams has opened new possibilities to investigate these reactions - the very neutron-rich beams of the SPES facility [1] at relatively low intensities may enable the study of near- and sub-barrier fusion to exotic systems. However, the use of RIBs is often very challenging because of the low available intensities and the forward focusing of the fusion evaporation residues (ER). Thus, applications of radioactive beams require detection systems with very high efficiency and detectors that avoid unnecessary energy straggling and angular dispersion and assure fast response.
A new set-up for fusion cross section measurements, especially designed for the low intensity beams which will be delivered by the SPES facility, has been developed and installed and it is presently in use at the National Laboratories of Legnaro (LNL), in its initial operation phase. The set-up is inspired on a similar one built at Oak Ridge [2] some years ago, with a significant improvement due to the use of a very fast ionization chamber (IC). This new fast IC is designed to ensure a high-counting-rate particle identification for fusion studies involving exotic beams up to 105 pps. Indeed, the IC will be placed at 0° with respect to the beam direction without filtering out the beam ions in any way. To reduce the response time of the ionization chamber, a design using a series of tilted electrodes has been adopted [3]. The aim is to be able to detect and identify fusion events within a counting rate up to 100-200 kHz. The set-up already existing at LNL for fusion measurements (based on the electrostatic beam deflector) has been upgraded by using the new IC and will remain in use for experiments with high-intensity stable (and upcoming exotic) beams. Several tests with stable beams have been performed to optimize the performance of the Fast IC [4]. The detector has been also employed for the experimental study of sub-barrier fusion in the 36S + 50Ti, 51V systems [5]. Aim of the experiment was to investigate possible effects of the non-zero spin of 51V ground state on the sub-barrier excitation function and on the shape of the barrier distribution. The fundamental concepts of a IC with fast response will be presented, the results of the in-beam tests and experiment performed will be showed in this seminar.
REFERENCES
[1] The SPES project: technical and scientific reports http://www.lnl.infn.it/ spes/
[2] D. Shapira et al., Nucl. Instr. Meth. Phys. Res. A 551, 330 (2005)
[3] K.Y. Chae et al., Nucl. Instr. Meth. Phys. Res. A 751, 6 (2014)
[4] G.Colucci et al., Acta Phys. Pol. B 50, 573 (2019)
[5] G. Colucci at al., Eur. Phys. J. A 55, 111 (2019)
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