Physics of Particles and Nuclei Letters最新文献

The article compares the results of instrumental neutron activation analysis (INAA) obtained with the ²⁵²Cf based INAA facility using at the Institute of Chemistry, Far Eastern Branch of the Russian Academy of Sciences (ICh FEB RAS) and data from the IREN facility at the Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research (FLNP JINR). INAA results are affected not only by the ratio of thermal to resonance neutron fluxes in the sample irradiation zone but also by the nuclear-physical characteristics of the analyzed elements. The results demonstrate that the previously used approach for correcting neutron flux inhomogeneity using La-containing monitors is inadequate. Application of this normalization procedure leads to an underestimation of INAA results for several elements, which is confirmed by interlaboratory comparisons. The greatest discrepancies between INAA data from ICh FEB RAS and FLNP JINR are observed for elements with a thermal neutron capture cross-section to resonance integral ratio greater than 10 (e.g., As, Sm, Au). The use of element-specific normalization coefficients significantly improved result accuracy. Comparison of the corrected INAA data obtained at the ICh FEB RAS on ore certified reference materials (CRMs) with the results obtained at the IREN facility confirms the validity of this approach and highlights its potential for reliable analysis of complex mineral raw materials in the Far Eastern region of Russia.

The decays of the η mesons ({eta mathord{left/ {vphantom {eta {eta {kern 1pt} '}}} right. kern-0em} {eta {kern 1pt} '}} to pi gamma gamma ) and (eta {kern 1pt} ' to eta gamma gamma ) are considered within the Nambu–Jona-Lasinio model. It is shown that vector channels give the main contribution. An analysis of the influence of the decay constants of vector mesons on the widths of these processes is carried out taking into account the electromagnetic interactions of these mesons. The obtained results are in satisfactory agreement with experimental data.

This work presents the general concept of a storage ring structure for the investigation of the electric dipole moment (EDM) of the proton and deuteron. The main features of frozen-spin and quasi-frozen-spin structures, designed to suppress spin rotation due to the magnetic dipole moment (MDM), are described. For the implementation of the proposed methods, the dependence of the fields in spin-compensating elements is determined.

This work investigates the structural and decay properties of ({text{odd}}{-} A) niobium (Nb) isotopes with mass numbers ranging from 71 ( leqslant A leqslant ) 147 using the relativistic Hartree–Bogoliubov (RHB) framework with the density-dependent DD-ME2 parameter set. Key bulk properties, including binding energies, root-mean-square radii, quadrupole deformation parameters, neutron separation energies, and decay half-lives, are systematically analysed. The results show good agreement with the Weizsäcker–Skyrme mass formula, the finite-range droplet model, and available experimental data. Notable discrepancies in the quadrupole deformation predictions, along with the anomalous weakening of half-lives in (^{{95,97}})Nb, emphasise the need for further theoretical refinement and experimental investigation to better understand the nuclear structure mechanisms in this region.

Dating is one of the most important tasks in archaeology. Studies of elemental composition using neutron activation analysis, combined with statistical data treatment, enable the establishment of indirect dating for the investigated artifacts. In this study, 11 mortar samples were studied. The samples were collected from buildings located on the territory of the Yuryev Monastery (Veliky Novgorod, Russia). For irradiation, the IREN facility at Joint Institute for Nuclear Research (Russia) and the WWR-K reactor at Institute of Nuclear Physics (Kazakhstan) were used. Using neutron activation analysis, mass fractions of 34 chemical elements were obtained. By applying multivariate statistical methods (hierarchical cluster analysis, principal component analysis, and factor analysis), it was established that the elemental composition of mortars from various historical periods differs significantly. This enabled the identification of groups corresponding to specific historical periods. It was shown that the content of rare earth elements in samples dating back to the pre-Mongol period is elevated compared to samples with later dating. The obtained data enabled the classification of samples with unknown dating using the method of indirect dating.

The radiative proton-capture of (^{{94}}{text{Mo}})(p, γ)(^{{95}}{text{Tc}}) and the stellar weak rates for ⁹⁴Mo are calculated within the frameworks of the Hauser–Feshbach theory and proton–neutron quasi-particle random phase approximation (pn-QRPA) model. The radiative capture rates, utilizing both phenomenological and microscopic nuclear inputs, are constrained by the experiment based on the rms error. The fitted capture cross-sections are used to predict the thermonuclear reaction rates at various stellar densities and temperatures. Using the constrained rates, the destructive rates are calculated using a set of relative hydrogen abundances and stellar densities as suited for SNIa and SNII environments. At the same densities and temperatures, the stellar weak rates are analyzed within the framework of pn-QRPA under the deformed basis. Both the temperature-dependent stellar weak rates and the destructive rates (p, γ) are investigated at the same densities and temperatures.

In this paper, we consider the features of the figure-8 accelerator from the spin dynamics point of view. Some of the main advantages of such a structure are: the absence of spin resonance crossing during beam acceleration and the ability to manipulate polarization in the spin-transparent mode. In this paper, we numerically verify the hypothesis that the figure-8 ring is characterized by a spin coherence time of several hours; we consider the influence of second-order deviations in phase coordinates on decoherence. The modifications of the figure-8 ring to search for a signal of axion-like particles and the electric dipole moment of light nuclei are also presented.

A mobile analyzer of the elemental composition of soil based on the tagged neutron method has been developed. The analyzer consists of a neutron module towed across the field by a transport platform. Elemental analysis of the soil is carried out in real time without sampling. The results of field tests of the analyzer are discussed.

The paper investigates the phenomenon of transverse bending of rod fuel elements of the active zone under the influence of temperature, which plays an important role in the dynamics of a periodic pulse reactor. Analytical calculation of thermoelastic deformation showed that positive feedback is directly related to the method of fixing the fuel elements. The possibility of fixing, eliminating the positive effect of reactivity, is demonstrated, and ways of technical solution of the problem are proposed.

The knowledge of the stress and strain state in rock sample is of importance in the understanding of the rock properties for the interpretation of geodynamic processes and for geotechnical applications such as mining and tunneling. Recently, the topic of induced seismicity has become a major issue in geoenergy production (gas production, geothermal). Thus, the role of tectonic stress for the initiation of rock failure is of high scientific but also economic interest. The investigation of deformation with conventional lab scale experiments allows the determination of macro-strain in the cm- to m-range. On the nano to micro-scale, the application of diffraction methods offers the investigation of the strain which is localized in the crystal lattice, the so-called intra-crystalline strain. This localization of strain in a sample with dimensions in cm-range is achieved by strain scanning. Because of the low absorption properties of neutrons in matter, like metals and minerals, neutron diffraction is an excellent method for the investigation of strain in bulk samples, especially in multiphase samples, like rocks. The neutron time-of-flight strain diffractometer EPSILON operated at the pulsed neutron source IBR-2M at the JINR Dubna is designed for the investigation of residual and applied intra-crystalline strain of bulk samples. Because of the large wavelength-range (up to ({{lambda ;}} = {;}7.8{;mbox{AA}})) diffraction pattern with d spacings up to (d = 5.6~,{mbox{AA}}) can be investigated. Using the long flight path of about 107.03 m a good spectral resolution is achieved. That allows the investigation of multiphase rocks containing minerals with lower crystal symmetry. The diffractometer is equipped with an uniaxial applied stress device, allowing load states up to 100 kN, e.g., 150 MPa with sample diameters of 30 and 60 mm length. The investigations concentrated on 3 locations within the sample: in the centre, at the rim and at a location in-between (half-radius). To avoid immediate rock failure a pre-experiment to determine the failure stress has been performed. Sample OU-2 (sandstone) has been scanned for 4 load steps (0, 11.65, 23.5, 35.21 MPa axial load). For each load level, the intra-crystalline strain has been determined in the direction of ({{sigma }_{1}}) and ({{sigma }_{3}}). A newly developed analysis tool which uses all diffraction peaks for detection of the lattice deformations has been applied to determine the in situ modulus of elasticity and the Poisson´s ratio at different positions (rim, half-radius, center) within the sample.