Physics of Particles and Nuclei Letters最新文献

Neutrino oscillations are evidence of flavor violation of neutral leptons, but such a process has not yet been discovered in the sector of charged leptons. The search for flavor violation of charged leptons is one of the most interesting problems in modern physics. One of the experiments aimed at searching for this process, NA64, is a fixed target experiment at CERN. In the article is discussed the possibility of searching for conversion between charged leptons. Preliminary estimates of the sensitivity of NA64 in electron and muon beams are presented. The probability of observing the process in an experiment based on current statistics is also discussed.

Mass measurement allows to determine the full binding energy of the nucleus—the integral characteristic of all atomic and nuclear forces which is the key for solving the fundamental physics problems, which includes nuclear physics, astrophysics, physics of fundamental interactions and symmetries, neutrino physics. High precision mass spectrometry could solve the problems of proton and neutron shells location in the nucleus (precision ΔM/M ~ 10^–6), the study the nuclei deformation phenomena, searching of so-called “halo-nuclei”, the correct description of the heaviest elements formation during astrophysical r- and rp-processes of fast neutron and proton captures respectively (precision ΔM/M ~ 10^–7). For this reason, a new facility for the high precision mass-spectrometry of heaviest nuclei is being built at the Flerov Laboratory of Nuclear Reactions, JINR, Dubna. It will include new target block, gas-filled separator for the reaction products, cryogenic gas-filled ion stopping cell (“Cryocell”), radio-frequency quadrupole transport system and the multi-reflection time-of-flight mass-spectrometer (MR-TOF-MS). This setup could provide mass measurements with the precision of about ΔM/M ~ 10^–7. “Cryocell” is one of the most crucial component of it. This is a powerful instrument for the fundamental research due to its high conversion coefficient of the fluxes of reaction products with heavy ions at energies 5–10 MeV/nucleon into low energy secondary beam and low extraction time. It could open the possibility to perform mass analysis of short-lived isotopes with the lifetime of 100 ms and more.

The NA65 (DsTau) experiment studies the tau neutrino production in accelerator beams, following the sequential ({{D}_{s}}) decays. For registering short lived particles, produced in high energy proton-nuclear interactions, the experiment uses a set-up based on nuclear tracking emulsion detectors.The present report shows the capabilities of the reconstruction of the primary proton interactions in the detector, in a pile-up of ({{10}^{5}}{text{--}}{{10}^{6}}) particles/cm².

In quantum field theory an important role is played by various hypergeometric functions. Of particular interest is their close relationship with Feynman loop integrals. The latter are used to calculate higher corrections in perturbation theory to the measurable physical processes. Which becomes especially important now that the accuracy of measurements is increasing. There are many ways to solve Feynman loop integrals using hypergeometric functions. These solutions have the common property that the indices of the hypergeometric function linearly depends on a small parameter. And for practical calculations, it is necessary to obtain a Laurent expansion in this small parameter. In this case, it is desirable that the expansion elements be expressed in terms of well-defined functions that can be calculated with arbitrary precision. In this work we study the expansion of various hypergeometric functions in a Laurent series with respect to a small parameter in terms of multiple-polylogarithms. For this purpose, we mainly use the differential equation method and the Lee algorithm. Specifically, we will be interested in the generalized hypergeometric functions, the Appell and Lauricella functions. In these calculations, a particularly important role is played by the replacement of the variable: rational in one direction and irrational in the other. This issue is discussed with special attention.

Abstract

The boron neutron capture therapy technique has been appealing to advance the technical and medical development of aspects of malignant tumors. The concept of the method has been aimed at dose contribution by secondary particles for targeted tumor sites while neutron beams do not have enough radiation effects to damage healthy cells with an advantage. This study focused on calculating the dose deposition of secondary particles from nuclear reactions between various mono-energetic neutrons and ¹⁰B with different concentrations. In this simulation, we carried out the single-cell model of human glial tumors with several potential distributions of boron nanoparticles as L-BPA. The resulting absorbed boron dose was more significant than the dose from other particles on the lower part of epithermal neutron energy ranges when higher boron concentration. Accordingly, we estimated the DNA damage in the cell geometry with the sphere and ellipsoid caused by the secondary particles using the GEANT4-DNA toolkit, respectively. The findings highlight the importance of precise dose calculations of high LET particles and considering secondary particle effects when evaluating the efficacy of BNCT in tumor treatment.

Abstract

A light-sensitive protein from extremophile archaea Halobacterium salinarum, bacteriorhodopsin (HsBR), has found numerous applications in pharmacology, biotechnology, bioelectronics and other fields [1, 2] due to its ability to convert light energy into a gradient of hydrogen ions across the cell membrane. Despite a wide range of its practical applications, the quantum mechanism of proton transfer remains not fully discovered yet. For further investigation and cost-effective implementation of developments, a higher yield of BR-rich biomass is necessitated. Hereafter we present our findings regarding efficient synthesis of HsBR using its natural host, H. salinarum.

A PXI-compatible amplifier and preamplifier module for the ⁵⁷Fe Mössbauer spectroscopy is presented in this paper. This PXI-compatible amplifier and preamplifier was developed for the purpose of utilization with proportional gas counters sensitive to the 14.4 keV low energy gamma rays as a part of PXI-based spectrometers developed at Palacký University Olomouc. The module is based on the Amptek A225 and A206 integrated circuits. This solution allows miniaturization of the spectrometric system, as the amplifier and the preamplifier are in a form of one PXI module, which is built in the compact PXI-chassis. There is also no need for an additional power supply, as the developed module is powered by the PXI connector included in the PXI chassis. This study deals with a comparison of the developed PXI-compatible amplifier and preamplifier board with the Amptek PC25 board in the stand-alone box (powered by a laboratory power supply), and with the ORTEC commercially available amplifier (572A) and preamplifier (142PC). The focus of this study is a comparison of those setups considering the false detections, lost detections, the multichannel analysis spectra, the Mössbauer spectrum quality, and the resonance effect of Mössbauer spectra.

The (nu )GeN experiment aims to search for coherent elastic neutrino-nucleus scattering and to study the other rare processes. The experimental setup is located about 12 m from the center of the 3.1 GWth reactor no. 3 of Kalinin NPP providing the antineutrino flux of (3.6–4.4) × 10(^{{13}}) particles cm^–2 s^–1. The intense antineutrino flux gives a possibility to detect coherent elastic scattering of reactor antineutrinos on Ge nuclei in the regime of full coherence, as well as to study other properties of neutrinos.

(1{text{/}}{{N}_{c}}) corrections in the framework of nonlocal quark model are analyzed. The initial stage of generating diagrams is carried out in the QGRAF program. The data generated by QGRAF is processed and diagrams are selected with (1{text{/}}{{N}_{c}}) counting rules. The diagrams are classified to certain types. Subsequently, the expressions are transferred to the FORM analytical calculation program. The analysis of the Feynman diagrams for the pion transition form factor is performed.

Analysis of the reliability of available experimental and evaluated data on cross sections for three (n, p) reactions leading to the formation of isotopes in isomeric metastable states is performed. This examination is motivated by recent measurements carried out with neutrons with energies of about (14) MeV at the NRC “Kurchatov Institute”. The possibility of using the TALYS-1.9 software package in order to evaluate cross sections of mentioned reactions is demonstrated.