Vol.31,

The finite autocorrelation time of thermal noise is crucial to unidirectional transportation on the molecular scale. Therefore, it is important to understand the cause of the intrinsic picosecond autocorrelation time of thermal noise in water. In this work, we use molecular dynamics simulations to compare the autocorrelation behaviors of the thermal noise, hydrogen bonds, and molecular rotations found in water. We found that the intrinsic picosecond autocorrelation time for thermal noise is caused by finite molecular rotation relaxation, in which hydrogen bonds play the role of a bridge. Furthermore, the simulation results show that our method of calculating the autocorrelation of thermal noise, by observing the fluctuating force on an oxygen atom of water, provides additional information about molecular rotations. Our findings may advance the understanding of the anomalous dynamic nanoscale behavior of particles, and the applications of terahertz technology in measuring the structural and dynamical information of molecules in solutions.

629

Relativistic heavy-ion collisions create hot quark-gluon plasma as well as very strong electromagnetic (EM) and fluid vortical fields. The strong EM field and vorticity can induce intriguing macroscopic quantum phenomena such as chiral magnetic, chiral separation, chiral electric separation, and chiral vortical effects as well as the spin polarization of hadrons. These phenomena provide us with experimentally feasible means to study the nontrivial topological sector of quantum chromodynamics, the possible parity violation of strong interaction at high temperature, and the subatomic spintronics of quark-gluon plasma. These studies, both in theory and in experiments, are strongly connected with other subfields of physics such as condensed matter physics, astrophysics, and cold atomic physics, and thus form an emerging interdisciplinary research area. We give an introduction to the aforementioned phenomena induced by the EM field and vorticity and an overview of the current status of experimental research in heavy-ion collisions. We also briefly discuss spin hydrodynamics as well as chiral and spin kinetic theories.

955

In the present study, we investigate several textile coating pastes used in the market based on their radiation protection capability for gamma rays. The gamma ray mass absorption coefficients of some coating pastes doped with antimony, boron and silver elements have been investigated. It has been determined that the gamma ray mass attenuation coefficient decreases rapidly as the energy of the gamma rays increases. It was determined that the doping of the main printing paste with silver and antimony considerably increased the gamma ray absorption capability of main paste. However, the doping of the paste with boron reduces the mass absorption of gamma rays. In particular, the gamma ray mass absorption power of the main paste doped with silver and antimony was determined to be useful in the gamma energy range from 80 keV to 140 keV. This indicates that the newly doped textile material may be considered for radiation protection in the case of low-energy gamma rays.

771

579

Within the framework of the dinuclear system model, the multinucleon transfer dynamics for nearly symmetric nuclear collisions has been investigated. The reaction mechanism in the systems of ¹⁹⁸Pt+¹⁹⁸Pt and ²⁰⁴Hg+¹⁹⁸Pt were investigated at beam energies around the Coulomb barrier. It was found that the isotopic yields are enhanced with increased incident energy in the domain of proton-rich nuclides. However, the production on the neutron-rich side weakly depends on the energy. The angular distribution with the beam energy was also analyzed in the multinucleon transfer reactions. Projectile-like fragments were produced towards the forward emission with increasing incident energy. The target-like fragments manifested the opposite trend in the transfer reactions.

677

Simulations of infinite nuclear matter at different densities, isospin asymmetries, and temperatures are performed using the Isospin-dependent Quantum Molecular Dynamics (IQMD) model to study the equation of state (EOS) and symmetry energy. A rigorous periodic boundary condition is used in the simulations. Symmetry energies are extracted from the binding energies under different conditions and compared to the Classical Molecular Dynamics (CMD) model using the same method. The results show that both models can reproduce the experimental results for the symmetry energies at low densities, but IQMD is more appropriate than CMD for nuclear matter above the saturation density. This indicates that IQMD may be a reliable model for the study of the properties of infinite nuclear matter.

974

Investigating deuteron-deuteron (DD) fusion reactions in a plasma environment similar to the early stages of the Big Bang is an important topic in nuclear astrophysics. In this study, we experimentally investigated such reactions, using eight laser beams with the third harmonic impacting on a deuterated polyethylene target at the ShenGuang-II Upgrade laser facility. This work focused on the application of range-filter (RF) spectrometers, assembled from a 70 μm aluminum filter and two CR-39 nuclear track detectors, to measure the yields of primary DD-protons. Based on the track diameter calibration results of 3 MeV protons used to diagnose the tracks on the RF spectrometers, an approximate primary DD-proton yield of (8.5±1.7)10⁶ was obtained, consistent with the yields from similar laser facilities worldwide. This indicates that the RF spectrometer is an effective way to measure primary DD-protons. However, due to the low yields of D³He-protons and its small track diameter, CR-39 detectors were unable to distinguish it from the background spots. Using other accurate detectors may help to measure these rare events.

601

A loss-of-coolant accident (LOCA) is one of the basic design considerations for nuclear reactor safety analysis. A LOCA induces propagation of a depressurization wave in the coolant, exerting hydrodynamic forces on structures via fluid-structure interaction (FSI). The analysis of hydrodynamic forces on the core structures during a LOCA process is indispensable. We describe the implementation of a numerical strategy for prestressed structures. It consists of an initialization and a restarted transient analysis process, all implemented via the ANSYS Workbench by system coupling of ANSYS and Fluent. Our strategy is validated by making extensive comparisons of the pressures, displacements, and strains on various locations between the simulation and reported measurements. The approach is appealing for dynamic analysis of other prestressed structures, owing to the good popularity and acknowledgement of ANSYS and Fluent in both academia and industry.

915

Rare event search experiments are one of the most important topics in the field of fundamental physics, and high purity germanium (HPGe) detectors with an ultra-low radioactive background are frequently used for such experiments. However, cosmogenic activation contaminates germanium crystals during transport and storage. In this study, we investigated the movable shielding containers of HPGe crystals using Geant4 and CRY Monte Carlo simulations. The production rates of ⁶⁸Ge, ⁶⁵Zn, ⁶⁰Co, ⁵⁵Fe, and ³H were obtained individually for different types of cosmic rays. The validity of the simulation was confirmed through a comparison with the available experimental data. Based on this simulation, we found that the interactions induced by neutrons contribute to approximately 90% of the production rate of cosmogenic activation. In addition, by adding an optimized shielding structure, the production rates of cosmogenic radionuclides are reduced by about one order of magnitude. Our results show that it is feasible to use a shielding container to reduce the cosmogenic radioactivity produced during the transport and storage of high-purity germanium on the ground.

622

This paper presents the calibration of a neutron dose rate meter and the evaluation of its calibration factors (CFs) in several neutron standard fields (i.e., two standard fields with bare sources of ²⁵²Cf and ²⁴¹Am-Be, and five simulated workplace fields with ²⁴¹Am-Be moderated sources). The calibration in standard fields with bare sources was conducted by following the recommendations of the ISO 8529 standard. The measured total neutron ambient dose equivalent rates, denoted as H˙(10)tot, were analyzed to obtain direct components, denoted as H˙*(10)dir, using a reduced fitting method. The CF was then calculated as the ratio between the conventional true value of the neutron ambient dose equivalent rate in a free field, denoted as H˙*(10)FF, and the value of H˙*(10)dir. In contrast, in the simulated workplace neutron fields, the calibration of the neutron dose rate meter was conducted by following the ISO 12789 standard. The CF was calculated as the ratio between the values of H˙*(10)tot measured by a standard instrument (i.e., Bonner sphere spectrometer) and the neutron dose rate meter. The CF values were obtained in the range of 0.88–1.0. The standard uncertainties (k = 1) of the CFs were determined to be in the range of approximately 6.6–13.1%.

594