Regular articles

2021

1. Application of a momentum-space semi-locally regularized chiral potential to selected disintegration processes

   Urbanevych, V., Skibiński, R., Witała, H., Golak, J., Topolnicki, K., Grassi, A., Epelbaum, E., and Krebs, H.

   Phys. Rev. C 2021

   Abs

   We apply a recently developed momentum-space semilocally regularized chiral potential to the 2H and 3He photodisintegration processes and to the (anti)neutrino induced deuteron breakup reactions. Specifically, the differential cross section, the photon analyzing power, and the final proton polarization have been calculated for deuteron photodisintegration at photon energies of 30 and 100 MeV. For 3He photodisintegration, predictions for the semi-inclusive and exclusive differential cross sections are presented for photon energies up to 120 MeV. The total cross section is calculated for (anti)neutrino disintegration of the deuteron for (anti)neutrino energies below 200 MeV. Predictions based on the Argonne V18 potential and on an older chiral force with regularization applied in coordinate space are used for comparison. Using the fifth-order chiral nucleon-nucleon potential supplemented with dominant contributions from the sixth order allows us to obtain converged predictions for observables in the investigated reactions. Our results based on the newest semilocal chiral potentials show even smaller cutoff dependence and a somewhat faster convergence for the considered electroweak observables than the previously reported ones with a coordinate-space regulator, which make them a promising tool to study electroweak processes.

2. A systematic study of LYSO:Ce, LuAG:Ce and GAGG:Ce scintillating fibers properties

   Rusiecka, K., Hetzel, R., Kasper, J., Kozani, M. Kazemi, Kohlhase, N., Kołodziej, M., Lalik, R., Magiera, A., Migdał, W., Rafecas, M., Stahl, A., Urbanevych, V., Wong, M.L., and Wrońska, A.

   Journal of Instrumentation 2021

   Abs

   Properties of different scintillating fibers were examined and compared, as a part of the design optimization of the SiFi-CC detector, currently under development for proton therapy monitoring. Three scintillating materials were considered as candidates to constitute the active part of the detector: LYSO:Ce, LuAG:Ce and GAGG:Ce. All investigated samples had an elongated, fiber-like shape and were read out on both ends using silicon photomultipliers (SiPMs). Samples of LYSO:Ce material provided by four different manufacturers were included in the survey. Additionally, different types of optical coupling media, wrapping and coating materials were investigated. The following properties of the scintillating fibers were determined: attenuation length, position-, energy-, timing resolution and light collection. Two models were used to describe the propagation of scintillating light in the fiber and quantify the light attenuation: exponential light attenuation model (ELA) and exponential light attenuation model with light reflection (ELAR). Energy and position reconstruction were also performed using the two above methods. It was shown, that the ELAR model performs better in terms of description of the light attenuation process. However, energy and position reconstruction results are comparable for the two proposed methods. Based on the results of measurements with scintillating fibers in different configurations we concluded that LYSO:Ce fibers wrapped in Al foil (bright side facing towards the fiber) provided the best trade-off between the energy- (8.56% at 511 keV) and position (32 mm) resolutions and thus will be the optimal choice for the SiFi-CC detector. Additionally, the study of different optical coupling media showed, that the silicone pads coupling ensures good stability of the system performance and parameters.

2020

1. Investigation of the interaction of circularly and linearly polarized photon beams with a polarized ^3\mathrmHe target

   Witała, H., Golak, J., Skibiński, R., Topolnicki, K., and Urbanevych, V.

   Phys. Rev. C 2020

   Abs

   Photodisintegration of polarized 3He by linearly or circularly polarized photons offers a rich choice of observables, which can be calculated with high precision using a rigorous scheme of three-nucleon Faddeev equations. Using the (semi)phenomenological AV18 nucleon-nucleon potential combined with the Urbana IX three-nucleon force we investigate sensitivity of 3He photodisintegration observables to underlying currents taken in the form of a single-nucleon current supplemented by two-body contributions for π- and ρ-meson exchanges or incorporated by the Siegert theorem. Promising observables to be measured for two- and three-body fragmentation of 3He are identified. These observables form a challenging test ground for consistent forces and currents being under derivation within the framework of chiral perturbation theory. For three-body 3He photodisintegration several kinematicaly complete configurations, including SST and FSI, are also discussed.

2. Newton’s second law analogy for the traveling wave of nuclear burning

   Urbanevych, Vitalii, Sharph, Igor, Tarasov, Viktor, and Rusov, Vitaliy

   EPJ Nuclear Sciences & Technologies 2020

   Abs

   We consider a model of neutron-nuclear wave burning. The traveling wave of nuclear burning of the medium is initiated by an external neutron source and is the basis for the new generation reactors the so-called “traveling-wave reactors”. We develop a model of nuclear traveling wave burning, for which it is possible to draw a Newton’s second law analogy with a mechanical dissipative system. On the basis of this analogy, we find that the wave velocity has a continuous spectrum bounded below. Within the framework of the new model, we show the autowave to be possible for certain neutron energies only. Also we find that two burning modes are possible depending on the control parameters: a traveling autowave and a wave driven by an external neutron source.

Conference proceednigs

2021

2020

1. An application of chiral forces with the semi-local regularization in momentum space to the deuteron photodisintegration process

   Urbanevych, V., Golak, J., Skibiński, R., and Witała, H.

   Journal of Physics: Conference Series 2020

   Abs

   A recent paper by P. Reinert et al. [Eur. Phys. J. A54, 86 (2018)] showed a possibility of improving chiral nucleon-nucleon potential models by employing a semi-local regularization in momentum space. The authors derived nucleon-nucleon potentials with this kind of regularization completely up to the fifth order of the chiral expansion and considered additionally some contact interactions which appear at the sixth order. Such a chiral interaction has never been applied to study electromagnetic processes in two- or three-nucleon systems. Here we continue our research of photodisintegration processes, now using the improved chiral force. In particular, we discuss our predictions for the deuteron photodisintegration reaction in the photon energy range up to 100 MeV. The results of our calculations reveal that the new potential yields predictions characterized by a weaker dependence on the regularization parameter and faster convergence with respect to the chiral expansion order compared to the older chiral potentials.

2. Investigations of the few-nucleon systems within the LENPIC project

   Golak, Jacek, Epelbaum, Evgeny, Grassi, Alessandro, Hiroyuki, Kamada, Krebs, Hermann, Reinert, Patrick, Skibiński, Roman, Soloviov, Volodymyr, Topolnicki, Kacper, Urbanevych, Vitalii, Volkotrub, Yuriy, and Witała, Henryk

   SciPost Physics Proceedings 2020
3. The application of chiral forces to the deuteron photodisintegration process at Eγ= 140 MeV

   Urbanevych, Vitalii, Golak, Jacek, Skibiński, Roman, and Witała, Henryk

   Acta Physica Polonica. B, Proceedings Supplement 2020
4. Neutron-deuteron scattering (chiral potentials & regulator dependence)

   Skibiński, Roman, Golak, Jacek, Soloviov, Volodymyr, Topolnicki, Kacper, Urbanevych, Vitalii, Volkotrub, Yuriy, and Witała, Henryk

   POS Proceedings of Science 2020

   Abs

   The predictions for the differential cross section and the deuteron tensor analyzing power T22 in nucleon-deuteron elastic scattering based on two chiral models of the nucleon-nucleon interaction are presented and compared with each other and with the data. The recent models at the fifth order of the chiral expansion from the Moscow(Idaho)-Salamanca group and from the Bochum group are used. At the energy of the incoming nucleon E=65 MeV both potentials yield similar data descriptions, however the differences between both models become more significant at E=200 MeV. At the latter energy the dependence of predictions on the used value of the regularization parameter becomes important. In particular, this cutoff dependence is much smaller in the case of the semilocally momentum space regularized potential from the Bochum group.

5. The first application of the chiral SMS nucleon–nucleon interaction to the deuteron photodisintegration process

   Urbanevych, Vitalii, Golak, Jacek, Skibiński, Roman, and Witała, Henryk

   Acta Physica Polonica. B 2020

   Abs

   A chiral nucleon–nucleon potential has been recently further improved by employing a semi-local regularization in momentum space. As such, a potential has not been tested yet in an electromagnetic process, we apply it to the deuteron photodisintegration reaction with photon energies up to 100 MeV. Results of our calculations show a weaker dependence of a selected observable on the cut-off parameter and a faster convergence with respect to the chiral expansion order compared to older chiral potentials.