Physics of Atomic Nuclei最新文献

A method for extrapolating the results of variational calculations to the case of the infinite basis using an ensemble of artificial neural networks is proposed. Extrapolations of the no-core shell model results obtained with the nucleon–nucleon interaction Daejeon16 for the ground state energies, as well as for the root-mean-square (rms) point-proton, point-neutron, and point-nucleon (matter) radii of the ({}^{6})Li and ({}^{6})He nuclei, are performed.

The main goal of the TUS experiment was to search for and study ultra high-energy cosmic rays with energy of (E>70) EeV. At the same time, the TUS detector registered several dozen of unusual events, the origin of which is unclear. Atmospheric gamma-ray bursts (TGF and TGE) are considered as their possible sources. In this work, anomalous events are used to calibrate the TUS photodetector.

The differential cross sections of the ({}^{19})F((alpha), (t))({}^{20})Ne(g. s., 2({}^{+}), 4({}^{+})) reaction studied at the cyclotron of the Skobeltsyn Institute of Nuclear Physics, (tgamma) angular correlations in the reaction ({}^{19})F((alpha), (t))({}^{20})Ne(2({}^{+})) at the energy (E=30.3) MeV, and the tensors of the orientation (t_{kkappa}(theta_{t})) of the multipole moments and the alignments (F_{k})((theta_{t})) of the ({}^{20})Ne(2({}^{+})) nucleus reconstructed on their basis are compared with the calculated values under the assumption of a direct mechanism of proton stripping taking into account the coupling of channels using the Coupled-Channels Born Approximation method. A set of calculation parameters necessary for such a reaction mechanism was established and their specific values were determined. The calculated differential cross sections of the reaction ({}^{19})F((alpha), (t))({}^{20})Ne for all states of the rotational band agree with the experimental ones at (theta_{t}<120^{circ}), where the direct mechanism makes the main contribution. In the same region of (theta_{t}), (t_{kkappa}(theta_{t})) the calculated (F_{2})((theta_{t})) and (F_{4})((theta_{t})) of the ({}^{20})Ne(2({}^{+})) nucleus agree satisfactorily with the experimental data. It was found that their value at (theta_{t}<120^{circ}) is small, so the isotropy of the spin distribution in ({}^{20})Ne(2({}^{+})) is not violated. At large angles (theta_{t}), both the experimental and calculated values of (F_{4}) are approximately 0.5, which indicates a partial violation of this isotropy.

The paper examines the possibility of using 3D printing technology to manufacture structural elements of ionizing radiation detectors under low-background conditions. The results of measurements conducted with a scintillation detector housed in a housing made of PETG plastic are presented.

The results of the study of the Cherenkov monitor of proton beams with a large pulse current are presented. For proton beams with an energy of 160 MeV and a pulse current of 4 mA, good agreement was obtained between the monitor measurements and the data of the beam current transformer. Bench measurements of the position coordinates of the light beam simulating the light image of the proton beam in the radiator of the 2-coordinate monitor were carried out. An analysis of the algorithms for restoring the position coordinates of the light beam is presented.

The article presents the results of the study of the flux-weighted average cross sections of ({}^{185-190})Ir and ({}^{192})Ir nuclei production in ((gamma,xn)) reactions when a natural mixture of iridium isotopes is irradiated with bremsstrahlung with an end-point energy of 55 MeV. For the first time, the experimental data on the weighted average cross sections of photoneutron reactions with the emission of up to six particles are compared with the theoretical weighted average cross sections calculated in the constant-temperature Fermi gas model and the Gogny–Hartree–Fock–Bogoliubov nuclear mass model using the TALYS1.96 program code. It is shown that the cross sections of the studied reactions are simultaneously successfully described only by the constant-temperature Fermi gas model taking into account the pre-equilibrium processes.

The (3alpha) phenomenological model describes the structure of the carbon-12 nucleus as a cluster of three alpha particles. This model includes a pairwise (alpha{-}alpha) interaction and a three-body force. To fit the three-body potential, the ({}^{12})C data are used, while ensuring that the pair potential reproduces the (alpha{-}alpha) scattering data. Alternatively, the mass–energy compensation (MEC) effect can be used to simulate the effect of the three-body potential by adjusting the mass of the (alpha) particle within the effective-mass approach. We demonstrate the MEC effect for the (3alpha) ground state by numerically solving the differential Faddeev equation, in which the (alpha{-}alpha) interaction is described by the Ali–Bodmer potential. The effective masses of (alpha) particles are evaluated for the ground and excited (0^{+}) and bound (2^{+}) states. We demonstrate a coupling between the ground and first excited (0^{+}) states, indicated by an anti-crossing of these energy levels in the energy–mass coordinates. A correspondence between the effective mass and a three-body potential is demonstrated. We discuss the results of the (0^{+}_{2}) calculations for various models of the (alpha{-}alpha) interaction.

A simultaneous description of different spin independent and spin dependent reactions of nucleon–nucleon elastic scattering is obtained for all existing experimental data at low (sqrt{s}geq 3.6) GeV and high energies up to the last LHC energy. From the point of view of the generalized parton structure of hadrons which unifies parton distributions of the proton, neutron, antiproton and meson the corresponding electromagnetic and gravitomagnetic form factors were obtained. On the base of these form factors, the elastic scattering amplitude is obtained with taking into account the analytical properties such as unitarity, crossing symmetry, polynomial boundedness. As a result, the united description of the existing experimental data of the differential cross sections and spin correlation parameter (A_{N})((s,t)) is obtained with minimum fitting parameters.

We propose to use existing LHAASO detectors to study of the flavor composition of UHE astrophysical neutrino. Monte Carlo simulations show that large Water Cherenkov Detector Array (WCDA) is a suitable detector to record high energy near horizontal neutrino interactions, due to its cell structure and rather large size. Signature of such events is very clear thus allows us even to determine the neutrino flavor interacting in the WCDA. The mass of this detector is about 300 kt of water and it is not enough to accumulate many high-energy neutrino events in a near future. Nevertheless, it is running detector and we could develop suitable algorithms for this program and make a search for these events regarding WCDA as a prototype for future full-scale experiment. Moreover, existing of square km EAS array (Km2A) with many muon detectors makes it possible to have a powerful veto against a background flux of near-horizontal atmospheric muons.

New data on cross sections of the ((gamma,1n)) and ((gamma,2n)) reactions on the ({}^{68})Zn nucleus, for which the neutron yield cross sections of (sigma^{textrm{exp}}(gamma,xn)=sigma(gamma,1n)+2sigma(gamma,2n)) and the total photoneutron reaction (sigma^{textrm{exp}}(gamma,sn)=sigma(gamma,1n)+sigma(gamma,2n)) have been obtained in two experiments on the beams of bremsstrahlung, were determined using the possibilities of the experimental–theoretical method for the evaluation of cross sections of partial photoneutron reactions based on objective physical criteria. The contributions of partial reaction cross sections (sigma^{textrm{eval}}(gamma,in)=F_{i}^{textrm{theor}}timessigma^{textrm{exp}}(gamma,xn)) for (i=1) and (2) to the neutron yield cross section were evaluated using the ratios (F_{i}^{textrm{theor}}=sigma^{textrm{theor}}(gamma,in)/sigma^{textrm{theor}}(gamma,xn)) calculated within the combined photonuclear reaction model (CPNRM).