Simple collective model for nuclear chiral mode

A simple semi-analytical collective model that takes into account the limitations of the variation interval of the collective variable is suggested to describe the chiral dynamics in triaxial odd−odd nuclei with a fixed particle−hole configuration.The collective Hamiltonian is constructed with the potential energy obtained using the postulated ansatz for the wave function symmetric with respect to chiral transformation.By diagonalizing the collective Hamiltonian the wave functions of the lowest states are obtained and the evolution of the energy splitting of the chiral doublets in transition from chiral vibration to chiral rotation regime is demonstrated.

Reaction mechanisms in massive nuclei collisions and perspectives for synthesis of heavier superheavy elements

We discuss a hardship in synthesis of heaviest super heavy elements in massive nuclei reactions due to the hindrance to complete fusion of reacting nuclei caused on the onset of quasifission process which strongly competes with complete fusion and due to the strong increase of fission yields along the de-excitation cascade of the compound nucleus in comparison with the evaporation residue formation.The hindrance to formation of compound nucleus and evaporation residue is determined by the characteristic of the entrance channel.

The diffusion and concentration effects of formamide on a TiO₂surface in the presence of a water solvent

The formamide-titanium oxide interaction mechanism is a research target of great importance for understanding the elementary events of the origin of life: the synthesis of nucleoside bases and formation of biological molecules needed for life. Titanium oxide (TiO2) can act as a strongly adsorbing surface or a catalytic material. In the present study, a comparative molecular dynamics analysis performed to clarify the adsorbing and diffusion properties of liquid formamide on a TiO2 surface in the presence of water molecules. The structural features of the formamide concentration effect (the accumulation of molecules) on a TiO2 surface in the presence and absence of water solvent are cleared up. Modification of the formamide diffusion abilities mediated by a water solvent is observed to correlate with the formamide-water concentration distribution on the surface.

Database system for managing 20,00020-inch PMTs at JUNO

A database system,known as the large PMT characterization and instrumentation database system(LPMT-CIDS),was designed and implemented for the Jiangmen Underground Neutrino Observatory(JUNO).The system is based on a Linux+Apache+MySQL+PHP(LAMP)server and focuses on modularization and architecture separation.It covers all the testing stages for the 20-inch photomultiplier tubes(PMTs)at JUNO and provides its users with data storage,analysis,and visualization services.Based on the successful use of the system in the 20-inch PMT testing program,its design approach and construction elements can be extended to other projects.

Angular Distribution and Cross Section Measurements of ^(64)Zn(n,α)^(61)Ni Reaction for Neutron Energy 5 MeV

A twin gridded ionization chamber with dual parameter data acquisition sys-tem is used to study neutron induced charged particle emission reaction.The angulardistribution and cross section of n-particles from the 64Zn（n,α）61Ni reaction are meas-ured at neutron energy 5 MeV.

Design and testing of an internal hot-cathode-type PIG ion source for superconducting cyclotron

The superconducting cyclotron SC200 is intended to generate a 200 MeV, 400 nA proton beam for future particle therapy. The internal hot-cathode-type Penning ionization gauge (PIG) ion source for the SC200 is designed for the generation of hydrogen ions. A brief description of the design of ion source and test bench, which are used in SC200, is given in this paper. The ion source has been verified on the test bench, and the results indicated that the designed ion source meets the expected requirements. The lifetime of the filament exceeded 100 h in the test. In addition, the extraction voltage and the gas flow that influence the extracted ion current intensity have been tested in the experiment.

Methods for a blind analysis of isobar data collected by the STAR collaboration

In 2018,the STAR collaboration collected data from^(96)_(44)Ru+^(96)_(44)Ru and^(96)_(40)Zr+^(96)_(40)Zr at√^(S)NN=200 Ge V to search for the presence of the chiral magnetic effect in collisions of nuclei.The isobar collision species alternated frequently between 9644 Ru+^(96)_(44)Ru and^(96)_(40)Zr+^(96)_(40)Zr.In order to conduct blind analyses of studies related to the chiral magnetic effect in these isobar data,STAR developed a three-step blind analysis procedure.Analysts are initially provided a"reference sample"of data,comprised of a mix of events from the two species,the order of which respects time-dependent changes in run conditions.After tuning analysis codes and performing time-dependent quality assurance on the reference sample,analysts are provided a species-blind sample suitable for calculating efficiencies and corrections for individual≈30-min data-taking runs.For this sample,species-specific information is disguised,but individual output files contain data from a single isobar species.Only run-by-run corrections and code alteration subsequent to these corrections are allowed at this stage.Following these modifications,the"frozen"code is passed over the fully un-blind data,completing the blind analysis.As a check of the feasibility of the blind analysis procedure,analysts completed a"mock data challenge,"analyzing data from Au+Au collisions at√^(S)NN=27 Ge V,collected in 2018.The Au+Au data were prepared in the same manner intended for the isobar blind data.The details of the blind analysis procedure and results from the mock data challenge are presented.

An Interacting Two-Fluid Scenario for Dark Energy in an FRW Universe

We study the evolution of the dark energy parameter within the scope of a spatially homogeneous and isotropic Friedmann-Robertson-Walker(FRW)model filled with barotropic fluid and dark energy.To obtain the deterministic solution we choose the scale factor a(t)=(√te^(t)),which yields a time-dependent deceleration parameter(DP).In doing so,we consider the case minimally coupled with dark energy to the perfect fluid as well as direct interaction with it.

Octupole Deformation and Signature Inversion in ^(145)Ba

High spin states in neutron-rich odd-N ^(145)Ba nucleus have been investigated from study of promptγ-rays in spontaneous fission of^(252)Cf.The alternating parity bands are identified indicating octupole deformation with simplex quantum number s=-i.The ground state band shows signature splitting and inversion at low spin.These collective band structures exhibit the competition and co-existence between symmetric and asymmetric shapes.

Octupole Deformation Bands of πh_(11/2) in Neutron-Rich 145,147La Nuclei

Octupole deformation bands built onπh ll/2 orbital in neutron-rich odd-Z 145,147La nuclei have been investigated by measuring the promptγ-rays emitted from the 252Cf source.The alternating parity band structures and strong E1 transitions observed between negative-and positive-parity bands in both nuclei indicate the octupole deformation enhanced by the h ll/2 single proton coupling.According to observed energy displacements the octupole deformation becomes stable at the intermediate spin states.

Molecular dynamics simulations of a DNA photolyase protein: High-mobility and conformational changes of the FAD molecule at low temperatures

A molecular dynamics (MD) simulation is performed on a DNA photolyase to study the conformational behavior of the photoactive cofactor flavin adenine dinucleotide (FAD) inside the enzyme pocket. A DNA photolyase is a highly efficient light-driven enzyme that repairs the UV-induced cyclobutane pyrimidine dimer in damaged DNA. In this work, the FAD conformational and dynamic changes were studied within the total complex structure of a DNA photolyase protein (containing FADH–, MTHF, and DNA molecules) embedded in a water solvent. We aimed to compare the conformational changes of the FAD cofactor and other constituent fragments of the molecular system under consideration. The obtained results were discussed to gain insight into the light-driven mechanism of DNA repair by a DNA photolyase enzyme—based on the enzyme structure, the FAD mobility, and conformation shape.

An Electroscalar Energy of the Sun: Observation and Research

The observation of an electroscalar signal during the eclipse of the Sun by the Moon in 2008 was a starting point for the development and creation of the electroscalar field theory. This observation shows that such radiation has a long wavelength, and is longitudinal and extremely penetrating. The properties of the electroscalar and electromagnetic dynamics of a massive charged particle have been studied. An analogy between the linear theory of elasticity and Maxwell electrodynamics is made. The observed spectrum of radiation clarifying peculiar properties. Real sources of electroscalar radiation are determined. In accordance with the principle of least action, the Lagrangian of the electroscalar field and the field force acting on the particle are defined. The spectral expansion of the electroscalar field allowed us to establish that the field is longitudinal and aligned with the wave vector. At the heart of the electroscalar theory, which is compliant with the experimental data, is the four-dimensional scalar potential that describes radial vibrations of the electroscalar field source. The four-vector Maxwell electromagnetic potential and four-scalar potential neither form a single object in the Minkowski space nor interfere and, as a consequence, prove to be independent and unrelated differential relations. Moreover, a strong correlation between the spatial position of the particle and the field components allows and demonstrates a new degree of freedom in the electrodynamics of charged particles.

Correlations in Nuclear Interactions between ECM/u and Unexplained Experimental Observables

A new concept is introduced for the classification of “unresolved problems” in the understanding of interactions in thick targets irradiated with relativistic ions: The centre-of-mass energy per nucleon of a hypothetical compound nucleus from a primary interaction, ECM/u, is calculated and correlated with experimental observations in thick target irradia- tions. One observes in various reactions of relativistic primary ions with thick targets that there appears to be a thresh- old energy for reactions leading to “unresolved problems” which lies around ECM/u ~ 150 MeV. All “unresolved prob- lems” are exclusively observed above this threshold, whereas below this threshold no “unresolved problems” are found. A similar threshold at 158 ± 3 MeV exists for massive pion production in nuclear interactions. Hagedorn had proposed this threshold decades ago and it is known as the Hagedorn limit. In this paper we will only mention, but not elaborate on Hagedorn’s theoretical concept any further. Some considerations will be presented and further studies in this field are suggested.

铝合金电弧熔丝增材制造的冶金缺陷研究现状与展望

电弧熔丝增材制造(WAAM)已成为装备制造领域的重要发展方向之一,通过电弧加热熔化金属丝材,可在预设路径上逐层叠加堆积完成三维实体金属构件的增材制造成形,具有效率高且成本低的优点,尤其适合大尺寸铝合金构件的一体化增材制造成形。但由于铝合金固有的冶金行为特征,电弧熔丝增材制造中易出现冶金缺陷,如气孔、裂纹等问题,较大程度限制了产品力学性能的进一步提升,也严重制约了铝合金电弧熔丝增材制造技术的高效高质量发展。本文主要综述了电弧熔丝增材制造铝合金的气孔、裂纹等冶金缺陷问题,总结了缺陷形成机理、影响因素和抑制措施等方面的研究进展,并对铝合金电弧熔丝增材制造技术的未来发展方向进行了展望。

Charge self-trapping in two strand biomolecules:Adiabatic polaron approach

We investigate the properties of the excess charge(electron, hole) introduced into a two-strand biomolecule. We consider the possibility that the stable soliton excitation can be formed due to interaction of excess charge with the phonon subsystem. The influence of overlap of the molecular orbitals between adjacent structure elements of the macromolecular chain on the soliton properties is discussed. Special attention is paid to the influence of the overlapping of the molecular orbitals between structure elements placed on the different chains. Using the literature values of the basic energy parameters of the two-chain biomolecular structures, possible types of soliton solutions are discussed.

Afterpulse measurement of JUNO 20‑inch PMTs

In this study,we present the large photomultiplier tube(PMT)afterpulse measurement results obtained from the Jiangmen underground neutrino observatory(JUNO)experiment.A total of 11 dynode-PMTs(R12860)from the Hamamatsu company(Hamamatsu Photonics K.K.(HPK))and 150 micro-channel plate PMTs(MCP-PMTs,GDB-6201)from the NNVT company(North Night Vision Technology Co.,Ltd.(NNVT))were tested.Subsequently,an afterpulse model was built according to the afterpulse time distribution and the probability of occurrence for these two types of PMTs.The average ratio of the total afterpulse charge with a delay between 0.5μs and 20μs to the primary pulse charge is∼5.7%(13.2%)for the tested MCPPMTs(dynode-PMTs).The JUNO experiment will deploy 20,01220-inch PMTs;this study will benefit detector simulation,event reconstruction,and data analysis regarding the JUNO experiment.

Photonuclear reactions on stable isotopes of selenium at bremsstrahlung end-point energies of 10-23 MeV

In this study,experiments were performed at bremsstrahlung end-point energies of 10-23 MeV with the beam from the MT-25 microtron using theγ-activation technique.The experimental values of relative yields were compared with theoretical results obtained on the basis of TALYS with the standard parameters and the combined model of photonucleon reactions.Including isospin splitting in the combined model of photonucleon reactions allows describing experimental data on reactions with proton escape in the energy range from 10 to 23 MeV.Therefore,taking into account isospin splitting is necessary for a correct description of the decay of the giant dipole resonance.

1―2MeV能区~6Li(n,t)~4He反应微分截面与截面的实验测量

利用屏栅电离室对1.05、1.54及2.25MeV中子6Li(n,t)4He反应的微分截面与截面进行了实验测量。采用氚固体靶的T(p,n)3He反应产生准单能中子,用相对效率已知的BF3长中子管和238U裂变片相结合来测定绝对中子通量。将测量结果与已有数据进行了比较,1―2MeV能区6Li(n,t)4He反应截面的分歧在一定程度上得到了澄清。

轻核(n,x)反应微分截面的实验测量

对本课题组十几年来的(n,x)反应实验研究工作进行了评述.介绍了屏栅电离室的特点、构造与工作原理.用屏栅电离室在北京大学4.5MV静电加速器上测量了1—7MeV中子6Li(n,t)4He和10B(n,α)7Li反应的微分截面与截面,对实验结果进行了讨论.