Subjects: Physics >> Nuclear Physics submitted time 2024-05-11
Abstract： Reliable calculations of nuclear binding energies are crucial for advancing the research of nuclear physics. Machine learning provides an innovative approach to exploring complex physical problems. In this study, the nuclear binding energies are modeled directly using a machine-learning method called the Gaussian process. First, the binding energies for 2238 nuclei with Z > 20 and N > 20 are calculated using the Gaussian process in a physically motivated feature space, yielding an average deviation of 0.046 MeV and a standard deviation of 0.066 MeV. The results show the good learning ability of the Gaussian process in the studies of binding energies. Then, the predictive power of the Gaussian process is studied by calculating the binding energies for 108 nuclei newly included in AME2020. The theoretical results are in good agreement with the experimental data, reflecting the good predictive power of the Gaussian process. Moreover, the α-decay energies for 1169 nuclei with 50 ≤ Z ≤ 110 are derived from the theoretical binding energies calculated using the Gaussian process. The average deviation and the standard deviation are, respectively, 0.047 MeV and 0.070 MeV. Noticeably, the calculated α-decay energies for the two new isotopes 204Ac M. H. Huang et al., Phys. Lett. B 834, 137484 (2022) and 207Th H. B. Yang et al., Phys. Rev. C 105, L051302 (2022) agree well with the latest experimental data. These results demonstrate that the Gaussian process is reliable for the calculations of nuclear binding energies. Finally, the α-decay properties of some unknown actinide nuclei are predicted using the Gaussian process. The predicted results can be useful guides for future research on binding energies and α-decay properties.
Subjects: Physics >> Nuclear Physics submitted time 2024-05-10
Abstract： [Background]: The China Spallation Neutron Source (CSNS) provides a white neutron beam with an energy range from 0.5 eV to 300 MeV and a total beam intensity of up to 107n/s/cm2, serving as an excellent experimental platform for the measurement of neutron capture reaction cross sections. During normal operation, the CSNS generates two proton bunches separated by 410 ns, consecutively striking the target, resulting in a mixed neutron beam composed of two bunches with a 410 ns interval. To avoid interference between the effects of the two bunches and maintain the energy precision of neutron capture cross sections, experimental data need to be analyzed and reconstructed to restore the effects of individual bunches. [Purpose]: The existing parsing method can yield very refined unfolding results, but it is relatively complex and has a certain usage threshold. Therefore, a more convenient data processing method needs to be found. [Methods]: This work utilized mathematical operations to analyze and reconstruct the data, with 410 ns as the unit time, and processed the data with a channel width of 4100 ns. Additionally, a comparison was made of the impacts of this method and existing methods on the accuracy of neutron incident energy. [Results]: This work proposes a simplified data processing method that achieves the same energy resolution as existing methods in the low-to-medium energy range, providing a new data processing approach for similar experimental work. [Conclusions]: The simplified data processing method presented in this study effectively addresses the issue of excessive computational costs in analyzing low to medium energy neutron data from the CSNS. It offers a practical solution for experimental work requiring accurate analysis of neutron capture reactions in this energy range.
Subjects: Physics >> Nuclear Physics submitted time 2024-05-08
Abstract： Complementary Metal Oxide Semiconductor (CMOS) image sensor is gradually replacing CCD image sensor with small size, light weight, low power consumption, high integration and other characteristics. In the space radiation environment, it has protons, heavy particles, gamma rays, A large number of high-energy particles such as electrons, CMOS image sensors will be subject to the radiation effect of heavy ions and have permanent damage to them.This paper focuses on the mechanism of permanent damage of CMV4000 under heavy ion irradiation. CMV4000 images after heavy ion irradiation have obvious hot pixels (the dark current peak is several times higher than the dark current peak of other pixels usually shows that the gray value of the pixel is several times higher than that of other normal pixels), and the hot pixels will not disappear in the next frame image and subsequent images, so the hot pixels are not temporary.This paper also considers the comparison of image parameters of CMOS image sensor before and after irradiation and reveals the degradation mechanism of each parameter.
Subjects: Physics >> Nuclear Physics Subjects: Biology >> Radiobiology submitted time 2024-05-06
Abstract： Manned spaceflight and nuclear technology applications are running on a highway in China today. The radiation and nuclear safety will continue to be a major national demand in a long term. Thus, the continuous observation of new radiation protection molecular targets and related drugs is of great value to us. Our previous study has found that the circulating Insulin-like Growth Factor Binding Protein 3 (IGFBP-3) showed a significant increase after total body exposure of mice to ionizing radiation. However, the function of IGFBP-3 and the effects of it level change on radiation induced damages are still unclear. In this study, we set up the Igfbp3 gene overexpression and knock-down cell models in mouse Kupffer (MKC) cells. The CCK-8 assay, EdU assay, clone formation assay and microsphere phagocytosis experiment were performed for investing the proliferation activity, DNA replication activity and phagocytic ability of different cell models after carbon-ion irradiation. Moreover，mice were tail vein injected with recombinant IGFBP-3 protein at 2 hours before 5 Gy carbon-ion irradiation, and the survival curves of mice were drawn. The results showed that overexpression of IGFBP-3 protein significantly alleviated the radiation-induced decrease of the DNA replication activity, cell viability, clone formation rate, and phagocytic ability of MKC cells. On the contrary, the knock-down of IGFBP-3 protein expression reduced the above results. Injection of IGFBP-3 protein before carbon-ion exposure significantly delayed the time of death in mice. Our results indicate at the cellular and animal levels that IGFBP-3 protein has the potential to reduce radiation-induced damages and serve as a target for radiation protection. Through enhancing the radiation resistance and phagocytic ability of Kupffer cells in mice to reduce the risk of infection after radiation exposure might be the underlying mechanism of the effects of IGFBP-3 on radiation protection.
Subjects: Physics >> Nuclear Physics submitted time 2024-04-28
Abstract： The high-intensity heavy-ion accelerator facility (HIAF) is a scientific research facility complex composed of
multiple cascade accelerators of different types, which pose a scheduling problem for devices distributed over
a certain range of 2 km, involving over a hundred devices. The White Rabbit (WR), a technology-enhancing
Gigabit Ethernet, has shown the capability of scheduling distributed timing devices but still faces the challenge
of obtaining real-time synchronization calibration parameters with high precision. This study presents a calibra#2;
tion system based on a time-to-digital converter implemented on an ARM-based System-on-Chip (SoC). The
system consists of four multi-sample delay lines, a bubble-proof encoder, an edge controller for managing data
from different channels, and a highly effective calibration module that benefits from the SoC architecture. The
performance was evaluated with an average RMS precision of 5.51 ps by measuring the time intervals from 0
to 24000 ps with 120000 data for every test. The design presented in this study refines the calibration precision
of the HIAF timing system. This eliminates the errors caused by manual calibration without efficiency loss and
provides data support for fault diagnosis. It can also be easily tailored or ported to other devices for specific
applications and provides more space for developing timing systems for particle accelerators, such as white
rabbits on HIAF.
Subjects: Physics >> Nuclear Physics submitted time 2024-04-28
Abstract： The Shanghai Laser Electron Gamma Source (SLEGS, located in BL03SSID) beamline at the Shanghai Synchrotron Radiation Facility (SSRF) is a laser Compton scattering (LCS) gamma source used for the investigation of nuclear structure, which is in extensive demand in fields such as nuclear astrophysics, nuclear cluster structure, polarization physics, and nuclear energy. The beamline is based on the inverse Compton scattering of 10640 nm photons on 3.5 GeV electrons and a gamma source with variable energy by changing the scattering angle from 20° to 160°. γ-rays of 0.25–21.1 MeV can be extracted by the scheme consisting of the interaction chamber, coarse collimator, fine collimator, and attenuator. The maximum photon flux for 180° is approximately 10^7 photons/s at the target at 21.7 MeV, with a 3-mm diameter beam. The beamline was equipped with four types of spectrometers for experiments in (γ,γ’), (γ,n), and (γ,p α). At present, nuclear resonance fluorescence (NRF) spectrometry, flat efficiency neutron detector (FED) spectrometry, neutron time-of-flight (TOF) spectrometry, and light-charged particle (LCP) spectrometry methods have been developed.
Subjects: Physics >> Nuclear Physics Subjects: Nuclear Science and Technology >> Nuclear Detection Technology and Nuclear Electronics submitted time 2024-04-28
Abstract： A charged particle array, named MATE-PA, which serves as an auxiliary detec#2;tor system to the Multi-purpose Active-target Time projection chamber for nuclear astrophysical and exotic beam Experiments (MATE) has been con#2;structed. The array is composed of twenty single-sided strip-silicon detectors, covering around 10% of the solid angle. It is dedicated for the detection of reaction-induced charged particles which penetrate the MATE active volume. The performance of MATE-PA has been experimentally studied using an alpha source, and a 36-MeV 14N beam injected into the chamber of MATE, filled with a mixture gas of 95% 4He and 5% CO2 under the pressure of 500 mbar, at the Radioactive Ion Beam Line in Lanzhou (RIBLL). The results demonstrate good separation of light charged particles with the forward double-layer silicon detectors of MATE-PA. The energy resolution of the Si detectors was deduced to be about 1% (σ) for an energy loss of about 10 MeV by the α particles. The inclusion of MATE-PA helps improve particle identification, and increases the dynamic range for the kinetic energy of charged particles, in particular that of α particles up to about 15 MeV.
Subjects: Physics >> Nuclear Physics submitted time 2024-04-28
Abstract： Capacitors are widely used in pulsed magnet power supplies to reduce ripple voltage, store energy, and decrease power variation. In this study, DC-link capacitors in pulsed power supplies were investigated. By deriving an analytical method for the capacitor current on the H-bridge topology side, the root-mean-square value of the capacitor current was calculated, which helps in selecting the DC-link capacitors. The proposed method solves this problem quickly and with high accuracy. The current reconstruction of the DC-link capacitor is proposed to avoid structural damage in the capacitor’s current measurement, and the capacitor’s hot spot temperature and temperature rise are calculated using the FFT transform. The test results showed that the error between the calculated and measured temperature increases was within 1.5 ◦C. Finally, the lifetime of DC-link capacitors was predicted based on Monte Carlo analysis. The proposed method can evaluate the reliability of DC-link capacitors in a non-isolated switching pulsed power supply for accelerators and is also applicable to film capacitors.
Subjects: Physics >> Nuclear Physics submitted time 2024-04-18
Abstract： Based on the dinuclear system model, the calculated evaporation residue cross sections matched well with the current experimental results. The synthesis of superheavy elements Z = 121 was systematically studied through combinations of stable projectiles with Z = 21–30 and targets with half-lives exceeding 50 d. The influence of mass asymmetry and isotopic dependence on the projectile and target nuclei was investigated in detail. The reactions 254Es (46Ti, 3n) 297121 and 252Es (46Ti, 3n) 295121 were found to be experimentally feasible for synthesizing superheavy element Z = 121, with maximal evaporation residue cross sections of 6.619 and 4.123 fb at 219.9 and 223.9 MeV, respectively.
Subjects: Physics >> Nuclear Physics Subjects: Physics >> The Physics of Elementary Particles and Fields submitted time 2024-04-15
Abstract： The search for chiral magnetic effects (CME) in relativistic heavy-ion collisions helps us to understand CP symmetry breaking in strong interactions and the topological nature of the quantum chromodynamic (QCD) vacuum. A two-plane method was proposed based on the fact that the background and signal of CME have different correlations relative to the spectator plane and the participant plane. Using a multiphase transport model with different input strengths of CME, we revisit the two-plane method in isobar collisions at √sNN = 200 GeV. The relative correlations of the CME signal and background to two different planes were found to be different, which is inconsistent with the assumptions made in the current experimental measurements. The difference arises from the decorrelation of the CME relative to the spectator and participant planes, which originates from the final state interactions. Our finding suggests that the current experimental measurements may overestimate the fraction of the CME signal in the final state in relativistic heavy-ion collisions.
Subjects: Physics >> Nuclear Physics submitted time 2024-04-12
Abstract： A systematic comparison of the odd-$A$ cobalt isotopes $^{53-65}$Co’s negative parity halo states energy level structures indicates a level inversion between $9/2^-$ and $11/2^-$ in $^{55}$Co, and suggests that $^{53,57}$Co might exhibit strong collective effects. Shell model calculations based on the GXPF1A effective interaction reproduce well these nuclei’s halo state energy levels, along with the corresponding experimental values for magnetic moments and electric quadrupole moments. The shell model results show that the dominant proton configuration component in the ground state $7/2^-$ wave functions of $^{53-65}$Co is $ pi left(1f_{7/2} right)^7$. The excited states $9/2^-$ and $11/2^-$ in $^{55}$Co involve a competition between $1f_{7/2}$ proton excitation and $1f_{7/2}$ neutron excitation, leading to a possible level inversion between the $9/2^-$ and $11/2^-$ states. Moreover, using the Constrained Hartree-Fock (CHF) method to study the quadrupole deformation characteristics of $^{53,55,57}$Co, and combining the average occupancy numbers and configurations obtained from shell model calculations, the reasons why the excited state energies of $^{55}$Co are higher compared to other Co isotopes were analyzed.
Subjects: Physics >> Nuclear Physics submitted time 2024-04-08
Abstract： The study of nuclear isoscalar giant monopole resonance (ISGMR) is an important way to constrain nuclear incompressibility coefficient $K_ infty$, which provides important information for the understanding of nuclear astrophysics phenomena. At present, there is a serious discrepancy in the unified descriptions of the ISGMR in Pb and Sn isotopes, which prevents us from the accurate determination of $K_ infty$. In this paper, we reviewed the recent progress in understanding this problem within the framework of quasiparitcle random phase approximation as well as quasiparticle-vibration coupling models.
Subjects: Physics >> Nuclear Physics submitted time 2024-04-01
Abstract： Using two nuclear models, i) the relativistic continuum Hartree-Bogoliubov (RCHB) theory
and ii) the Weizs acker-Skyrme (WS) model WS$^ ast$,
the performances of nine kinds of kernel functions in the kernel ridge regression (KRR) method
are investigated by comparing the accuracies of describing the experimental nuclear charge
radii and the extrapolation abilities.
It is found that, except the inverse power kernel, other kernels can reach the same level
around 0.015-0.016~fm for these two models with KRR method.
The extrapolation ability for the neutron rich region of each kernel depends on the trainning data.
Our investigation shows that the performances of the power kernel and Multiquadric kernel are
better in the RCHB+KRR calculation, and the Gaussian kernel is better in the WS$^ ast$+KRR calculation.
In addition, the performance of different basis functions in
the radial basis function method is also investigated for comparison.
The results are similar to the KRR method.
The influence of different kernels on the KRR reconstruct function is discussed
by investigating the whole nuclear chart.
At last, the charge radii of some specific isotopic chains have been investigated
by the RCHB+KRR with power kernel and the WS$^ ast$+KRR with Gaussian kernel.
The charge radii and most of the specific features in these isotopic chains
can be reproduced after considering the KRR method.
Subjects: Physics >> Nuclear Physics submitted time 2024-03-28
Abstract： Charge exchange reactions with the intermediate energy can be used to study the complex structure of atomic nuclei from the respect of spin-isospin excitation. By utilizing the radioactive beam line at the Institute of Modern Physics, Chinese Academy of Sciences, charge exchange reaction experiments in inverse kinematics can expand the target nuclides to be studied to neutron-rich nuclei and even unstable nuclei. Based on this, a detector system for charge exchange reaction experiments has been designed, which mainly consists of a 3He gas target, TPC and CsI(Tl) arrays, where the TPC and CsI(Tl) arrays form a ΔE-E system. Using simulation software such as Geant4 and Garfield++, the operating conditions of the TPC were optimized, the kinematic intervals and the basic design of the detector for the experimental study were determined, and the particle discrimination ability of the detection system was investigated. Based on the simulation, the detection system was built.
Subjects: Physics >> Nuclear Physics submitted time 2024-03-27
Abstract： Background: The propagation and power deposition process of ion cyclotron waves in plasma is the key to ICRH.
Purpose: The purpose of this study is to evaluate the effect of single absorption assumption and non-single absorption assumption on ion cyclotron wave coupling and heating in the EAST.
Methods: Under different antenna current phases, the simulation results of the EAST 3D full vacuum chamber ICRH program and the 1/4 vacuum chamber ICRH program were compared.
Results: When the antenna current phase is (0 π 0 π), there is a significant difference between the simulation results of the two models.
Conclusion: The ion cyclotron wave propagating multiple times in the toroidal direction is the main reason for the difference in results. For fusion devices, the applicability of the single absorption assumption needs further systematic research.
Subjects: Physics >> Nuclear Physics submitted time 2024-03-22
Abstract： Meson beam and nucleus collision experiments have played an important role in the field of nuclear physics and particle physics at medium and high energies, especially in the study of hadron spectroscopy, where a series of important experimental measurements have been achieved. In this paper, several typical meson beam experiments in the world are summarized, including J-PARC experiment in Japan, COMPASS experiment, AMBER experiment and HIKE experiment planned at CERN, GlueX experiment and EIC project at JLab in the United States. Furthermore, parameters of secondary meson beam are estimated based on HIAF facility in China, and physical measurements are discussed. Through the investigation of these experimental projects, the purpose is to provide some inspiration and reference for the further planning and construction of meson beam experimental equipment in China and the related research on hadron physics.
Subjects: Physics >> Nuclear Physics submitted time 2024-03-19
Abstract： The exploration of exotic shapes and properties of atomic nuclei, e.g., α cluster and toroidal shape, is a
fascinating field in nuclear physics. To study the decay of these nuclei, a novel detector aimed at detecting
multiple alpha-particle events was designed and constructed. The detector comprises two layers of double-sided
silicon strip detectors (DSSD) and a cesium iodide scintillator array coupled with silicon photomultipliers array
as light sensors, which has the advantages of their small size, fast response, and large dynamic range. DSSDs
couple with cesium iodide crystal arrays are used to distinguish multiple alpha hits. The detector array has a
compact and integrated design that can be adapted to different experimental conditions. The detector array was
simulated using Geant4, and the excitation energy spectra of some alpha-clustering nuclei were reconstructed
to demonstrate the performance. The simulation results show that the detector array has excellent angular
and energy resolutions, enabling effective reconstruction of the nuclear excited state by multiple alpha particle
events. This detector offers a new and powerful tool for nuclear physics experiments and has the potential to
discover interesting physical phenomena related to exotic nuclear structures and their decay mechanisms
Subjects: Physics >> Nuclear Physics submitted time 2024-03-19
Abstract： In recent years, the gap between the supply and demand of medical radioisotopes has increased, necessitating new methods for producing medical radioisotopes. Photonuclear reactions based on gamma sources have unique advantages in terms of producing high specific activity and innovative medical radioisotopes. However, the lack of experimental data on reaction cross sections for photonuclear reactions of medical radioisotopes of interest has severely limited the development and production of photonuclear transmutation medical radioisotopes. In this study, the entire process of the generation, decay, and measurement of medical radioisotopes was simulated using online gamma activation and offline gamma measurements combined with a shielding gammaray spectrometer. Based on a quasi-monochromatic gamma beam from the Shanghai Laser Electron Gamma Source (SLEGS), the feasibility of the measurement of production cross section for surveyed medical isotopes was simulated, and specific solutions for measuring medical radioisotopes with low production cross sections were provided. The feasibility of this method for high precision measurements of the reaction cross section of medical radioisotopes was demonstrated.
Subjects: Physics >> Nuclear Physics submitted time 2024-03-19
Abstract： In heavy ion collisions (HICs), the production of light particles plays an important role in extracting information about the equation of state (EoS) of nuclear matter. Based on the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) model, the effect of the sequential decay on the collective flows and the nuclear stopping power of light particles in Au+Au collisions at intermediate energies were investigated, with the statistical decay model GEMINI++ is used to process the secondary decay of the primary fragments. It is found that due to the memory effect and the daughter nuclei produced by decay inherent part of the dynamic information of the parent nucleus, the experimental data can be better described by considering the sequential decay. And the influence of the sequential decay on the observables weakens with the increase of the collision energy. The results highlight that the sequential decay and the production of light particles in HICs have an obvious effect on the observables which sensitive to the EoS, and these effects should be considered when adopting these observables to extract the information of the EoS.
Subjects: Physics >> Nuclear Physics submitted time 2024-03-18
Abstract： By including octupole correlations in the Nilsson potential, the ground-state rotational bands in the
reflection-asymmetric (RA) nuclei are investigated by using the cranked shell model (CSM) with the monopole and
quadrupole pairing correlations treated by a particle-number-conserving (PNC) method. The experimental kinematic
moments of inertia (MoIs) of alternating-parity bands in the even-even nuclei 236,238U and 238,240Pu, and parity-doublet
bands in the odd-𝐴 nuclei 237U and 239Pu are well reproduced by the PNC-CSM calculations. Compared to the neighboring even-even nuclei 236,238U and 238,240Pu, 50% ∼ 60% increase of 𝐽(1) can be seen for the intrinsic 𝑠 = −𝑖 bands in 237U
and 239Pu. Those mainly attribute to the pairing reduction due to the Pauli blocking of the unpaired neutron occupying
the neutron orbitals near the Fermi surface. The gradual increase of 𝐽(1) versus rotational frequency can be explained
by the pairing reduction due to the rotation. The present calculation shows that the MoIs of the reflection-asymmetric
nuclei are higher than those of the reflection-symmetric (RS) nuclei at the low rotational frequency. Furthermore, compared with the RS nuclei, the pairing reduction of the RA nuclei increase when a larger octupole deformation 𝜀3 is
included in the calculation.
Hits
YES
Hits
Downloads
Comment