Zahlavi

Joint seminars of the NPI

The joint seminars of the Nuclear Physics Institute are reserved for subjects extending the scope of interests of one department (mainly seminars of the important guests, reviews on NPI groups and the outstanding results, usually in English).

Next seminar:

5. 2. 2026

Ján Kozic (DA NPI): Spectrometry of an external neutron source based on the p(24 MeV) + Be reaction driven by the TR-24 accelerator

Abstract:
Spectra of a neutron source driven by the TR-24 cyclotron and based on the p(24 MeV) + Be reaction were measured as part of a program aimed at developing spectral density monitoring for intense cyclotron-driven fast neutron sources at the Nuclear Physics Institute of the Czech Academy of Sciences (NPI CAS). A series of irradiation experiments were performed at the TR-24–driven high-power neutron generator (HPNG) to analyze neutron spectra for various source-to-sample geometrical arrangements. Neutron spectrometry was carried out using the dosimetry foil technique with activation detectors made of different materials, including Al, Au, Co, Cu, Fe, In, Lu, Nb, Ni, Ti, and Y. Reaction rates were determined by gamma-ray spectrometry and used as input for neutron spectrum unfolding. The neutron flux density at source-to-sample distances of 32.5, 42.5, 172.5 and 322.5 mm reached values of 1.90·109, 1.31·109, 9.33·107 and 2.82·107 cm-2μC-1, respectively. The HPNG is intended for research applications such as integral nuclear data validation and irradiation hardness testing of materials and instrumentation, with relevance to future nuclear technologies including Generation IV reactors, accelerator-driven systems, and fusion technology, as well as interdisciplinary research based on fast neutron activation analysis and the production of radionuclides for medical applications.

26. 2. 2026

Mgr. Petr Veselý, Ph.D. (DTP NPI): Description of double beta decay within beyond mean-field nuclear methods

Abstract:
Double beta decay (DBD) is a phenomenon which provides us unique window to physics beyond Standard Model and which lies at the intersection of particle, nuclear and atomic physics. It is of crucial importance to distinguish whether DBD occurs solely in two-neutrino or also neutrino-less variant. Possible discovery of neutrino-less or other exotic mode of DBD would have big consequences in next development of particle physics as well as cosmology. One of challenges in theoretical description of DBD is to provide precise nuclear matrix elements (NME) which enter to calculations of DBD's half-life.

In this seminar I will discuss two beyond-mean field nuclear methods - Equation of Motion Phonon Method (EMPM), and Second Tamm Dancoff Approximation (STDA) - which I apply to compute NME and DBD half-life of Calcium-48. In order to obtain reasonable values of DBD half-life,  it is necessary to introduce a phenomenological quenching of the weak coupling constant gA. I will also discuss whether the beyond mean-field configurations could, at least to some extent, provide explanation of this quenching. 
 

Archive of seminars:

2026

2025

2024 

2023

2022

  • Monday, September 9, 2019 - 10:00
    A. Turbiner (ICN-UNAM, Mexico and Stony Brook University, USA) 
    Choreography in Physics

 

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