分类： 物理学 >> 核物理学 提交时间： 2025-05-06
Luo, Mr. Yinfang
Lv, Mr. Jiahao
Xing, Dr. Yuan-ming
Zhang, Prof. Yuhu
Zhang, Mr. Min
Wang, Prof. Meng
Litvinov, Prof. Yuri
Zhou, Prof. Xiaohong 周小红
摘要： The technique of Bρ-defined isochronous mass spectrometry (Bρ-IMS), established at a storage ring, serves as a valuable tool for determining the masses of short-lived nuclei. In the previous Bρ-IMS experiments, the effects of magnetic field drifts have to be corrected in order to improve the mass resolving power of Bρ-IMS [Eur. Phys. J. A 59, 27 (2023)]. The correction procedures are complicated and require multiple reference ions with well-known masses in each injection, which may not be the cases in the measurements of exotic nuclei with tiny production yields. In this study, we propose a novel approach of Bρ-IMS that requires only one reference ion for mass determination in an individual injection, avoiding the tedious and complicated correction procedures. This approach achieves the mass precision comparable to that of previous Bρ-IMS results, and is approved to be suitable for future mass measurements of exotic nuclei with extremely low production yields.
分类： 物理学 >> 核物理学 提交时间： 2025-04-17
Bai, Dr. Ruxue
Guo, Prof. Hong-xia
Li, Mr. Yangfan
Ma, Dr. Wuying
Li, Dr. Jifang
Zhang, Mr. Feng-Qi
Ouyang, Dr. Xiaoping
Zhong, Prof. Xiangli
摘要： Gallium nitride (GaN)-based devices are highly attractive candidates for space and aeronautics due to their wide band gap and high critical electric field. However, the mechanism of radiation damage and long-term application reliability of the device are still unclear. This study systematically examines the degradation mechanisms of gate oxide layers in Cascode GaN power devices under proton irradiation at different energy levels. The typical degradation of electrical properties was observed. Following 25 MeV proton irradiation, the gate leakage current increased from 4.18×10-12 A to 4.42×10-10 A. After 60 MeV proton irradiation, the gate leakage current rose from 3.88×10-12 A to 3.81×10-10 A. In contrast, no significant change in gate current was observed after 100 MeV proton irradiation. Time-dependent dielectric breakdown (TDDB) analysis confirmed an elevated risk of gate current leakage under proton irradiation. Proton irradiation increases defect density in the device oxide layer, leading to the formation of leakage paths. In addition, SRIM simulation results based on Monte Carlo indicated that the interaction cross section between low-energy protons and target nuclei is larger, which will cause more defects in the device, leading to the low-energy proton damage becoming more severe. These radiation-induced defects in the gate oxide layer accelerate dielectric breakdown, ultimately compromising the device's long-term reliability.
分类： 天文学 >> 天文仪器与技术 提交时间： 2025-03-14 合作期刊: 《Astronomical Techniques and Instruments》
摘要： High-energy gamma-ray astronomy, at frequencies of 100 MeV to 100 GeV, yields insights into the fields of compact objects, extreme processes, and particle propagation. Thousands of gamma-ray sources have been detected by the Fermi Gamma-ray Space Telescope, many without any known counterpart at other wavelengths or clear identification of the source. Deep learning algorithms have been successfully applied to a variety of problems in astronomy. In this paper, I give some typical examples for classifying Fermi sources with deep learning methods, to show how such techniques can improve capability to unveil the nature of high-energy gamma-ray sources.
分类： 物理学 >> 核物理学 提交时间： 2025-02-02
摘要： We extend an analytical nucleon coalescence model with hyperons to study the productions of light nuclei, hypertritons and $\Omega$-hypernuclei in Pb+Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV. We derive the formula of the momentum distribution of two bodies coalescing into dibaryon states and that of three bodies coalescing into tribaryon states. We explain the available data of coalescence factors $B_2$ and $B_3$, transverse momentum spectra, averaged transverse momenta, yield rapidity densities and yield ratios of the deuteron, antihelium-3, antitriton and hypertriton measured by the ALICE collaboration. We give predictions of different $\Omega$-hypernuclei $H(p\Omega^-)$, $H(n\Omega^-)$ and $H(pn\Omega^-)$. We particularly study production correlations of different light (hyper-)nuclei and find two groups of interesting observables, the averaged transverse momentum ratios of light (hyper-)nuclei to protons (hyperons) and their corresponding yield ratios. The former group exhibits a reverse hierarchy of the nucleus size, and the latter is sensitive to the nucleus production mechanism as well as the nucleus's own size.
分类： 物理学 >> 核物理学 提交时间： 2025-01-06
Bai, Dr. Ruxue
Guo, Prof. Hong-xia
Li, Mr. Yangfan
Ma, Dr. Wuying
Li, Dr. Jifang
Zhang, Mr. Feng-Qi
Ouyang, Dr. Xiaoping
Zhong, Prof. Xiangli
摘要： In this paper, the effects of proton irradiation with different energies on the long-term reliability of gate-oxide in Cascode enhanced GaN power device is studied. The typical degradation of electrical properties was observed. In contrast, the gate current was increased by about two orders of magnitude after 25 MeV and 60 MeV proton irradiation, while the gate current was unchanged significantly after 100 MeV proton irradiation. By using time-dependent dielectric breakdown (TDDB) method confirms that the risk of gate current leakage is increased under proton irradiation. The breakdown time of gate dielectric becomes shorter after proton irradiation, which is not conducive to the long-term and stable application of GaN power devices. In addition, SRIM simulation results show that the interaction cross section between low-energy protons and target nucleus is larger, which will cause more defects in the device, leading to the low-energy proton damage becomes more severe. Proton irradiation produces defects in the gate-oxide layer that shorten the breakdown time of the device gate-oxide layer, ultimately resulting the long-term reliability of the device was reduced.
分类： 核科学技术 >> 辐射物理与技术 提交时间： 2024-04-08
摘要： In the framework of the Lanzhou Quantum Molecular Dynamics (LQMD) model, a possible probe to the neutron-skin thickness (δnp) of neutron-rich 48Ca is studied in 140A MeV 48Ca + 9Be projectile fragmentation reaction based on parallel momentum distribution (p//) of residual fragments.The Fermi-type density distribution is employed to initiate the neutron density distributions in the LQMD simulation. A combined Gaussian function with different width parameters for the left side (ΓL) and the right side (ΓR) in distribution are used to describe the p// of residual fragments. The value of ΓL, taking neutron-rich sulfur isotopes as examples, shows a sensitive correlation to δnp of 48Ca, which is suggested to be a probe to determine the neutron-skin thickness of the projectile nucleus.
分类： 物理学 >> 核物理学 提交时间： 2024-03-04
Fang-Lei Zou
Xiao-Jun Sun
Jing-Shang Zhang
Hai-Rui Guo
Yin-Lu Han
Rui-Rui Xu
Xi Tao
Ji-Min Wang
Xiao-Dong Sun
Yuan Tian
Tao Ye
Yong-Li Xu
Chun-Tian Liang
摘要： Based on the unified Hauser–Feshbach and exciton model, which can describe the particle emission processes between discrete energy levels with energy, angular momentum, and parity conservations, a statistical theory of light nucleus reaction (STLN) is developed to calculate the double-differential cross-sections of the outgoing neutron and light charged particles for the proton-induced 6Li reaction. A significant difference is observed between the p + 6Li and p + 7Li reactions owing to the discrepancies in the energy-level structures of the targets. The reaction channels, including sequential and simultaneous emission processes, are analyzed in detail. Taking the double-differential cross-sections of the outgoing proton as an example, the influence of contaminations (such as 1H, 7Li, 12C, and 16O) on the target is identified in terms of the kinetic energy of the first emitted particles. The optical potential parameters of the proton are obtained by fitting the elastic scattering differential cross-sections. The calculated total double-differential cross-sections of the outgoing proton and deuteron at Ep = 14 MeV agree well with the experimental data for different outgoing angles. Simultaneously, the mixed double differential cross-sections of 3He and α are in good agreement with the measurements. The agreement between the measured data and calculated results indicates that the two-body and three-body breakup reactions need to be considered, and the pre-equilibrium reaction mechanism dominates the reaction processes. Based on the STLN model, a PLUNF code for the p + 6Li reaction is developed to obtain an ENDF-6-formatted file of the double-differential cross-sections of the nucleon and light composite charged particles.
分类： 物理学 >> 核物理学 提交时间： 2023-11-04
摘要： The recent progresses on the wobbling motion are briefly introduced. So far 17 wobbling candidates have been reported in odd-$A$ and even-even nuclei that spread over $A approx 100$, 130, 160, and 190 mass regions. The two-quasiparticle configuration wobbling in $^{130}$Ba and the wobbling motion in a triaxial rotor are taken as examples in this paper to show the wobbling motion in even-even nuclei. The combination of covariant density functional theory and particle rotor model (CDFT+PRM) is a powerful theoretical method to study the wobbling motion. The time evolution of the wobbling motion is an interesting topic, from which the wobbling nature is intuitively revealed.
分类： 物理学 >> 核物理学 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要： Reaction dynamics in collisions of antiprotons on nuclei is investigated within the Lanzhou quantum molecular dynamics model. The reaction channels of elastic scattering, annihilation, charge exchange and inelastic collisions of antiprotons on nucleons have been included in the model. Dynamics on particle production, in particular pions, kaons, antikaons and hyperons, is investigated in collisions of p� on 12C, 20Ne, 40Ca and 181Ta from low to high incident momenta. It is found that the annihilations of p� on nucleons are of importance to the dynamics of particle production in phase space. Hyperons are mainly produced via meson induced reactions on nucleons and strangeness exchange collisions, which lead to delayed emission in antiproton-nucleus collisions.
分类： 物理学 >> 核物理学 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要： Nuclear double --decay with two neutrinos is an important decay mode for some unstable nuclei. Based on the available experimental data of nuclear double --decay, we propose that there is a law between the logarithm of double --decay half-lives and the reciprocal of the decay energy. The physics behind the law is discussed and it is found that this is associated with the universal properties of the weak interaction. This double --decay law is similar to the famous Geiger-Nuttall law of -decay. The law is applied to predictions of the nuclear double --decay half-lives for six even-even nuclei from Z=84 to Z=98 and we found that 232Th is very interesting for future experiments. The branching ratios between double --decay and -decay are also estimated for the six even-even nuclei and this is useful for future experimental search of new emitters of double --decay.
分类： 物理学 >> 核物理学 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要： Antiproton-induced reactions on nuclei at the beam energies from hundreds MeV up to several GeV provide an excellent opportunity to study interactions between the antiproton and secondary particles (mesons, baryons and antibaryons) with nucleons. The antiproton projectile is unique in the sense that most of the annihilation particles are relatively slow in the target nucleus frame. Hence, the prehadronic effects do not much influence their interactions with the nucleons of the nuclear residue. Moreover, the particles with momenta less than about 1 GeV/c are sensitive to nuclear mean field potentials. This paper discusses the microscopic transport calculations of the antiproton-nucleus reactions and is focused on three related problems: (i) antiproton potential determination, (ii) possible formation of strongly bound antiproton-nucleus systems, and (iii) strangeness production.
分类： 物理学 >> 核物理学 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要： We report our recent progress on the nuclear symmetry energy probe, which is called the isobaric yield ratio difference (IBD), and its application in neutron density determination in experiments. The results obtained by the IBD, from which the isobaric yields in the measured 140 A MeV 40, 48Ca + 9Be and 58,64Ni + 9Be reactions, and the calculated 80 A MeV 38-52Ca + 12C reactions by using a modified statistical abrasion-ablation model, show the sensitivity of the IBD to the density differences between reactions.
分类： 物理学 >> 核物理学 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要： In this work we study the symmetry-energy coefficient of neutron-rich nuclei, and the temperature dependence of nuclear symmetry energy at low temperatures. An isobaric method is used to extract the symmetry-energy coefficients of neutron-rich nucleus (asym) at zero temperature (T) and asym/T at nonzero temperature in the measured 1A GeV 124,136Xe+Pb reactions. T of fragment is obtained from the ratio of its asym to asym/T. The results show that, for fragment with the same neutron-excess (I=N‒Z), the heavier the fragment is, the higher T it has, and T tends to saturate around 1 MeV for the large mass fragments. It is also shown that the more neutron-rich the isobar is, the higher temperature it has. The T2 dependence of symmetry energy of finite nucleus at low temperatures is verified by the extracted results.
分类： 物理学 >> 核物理学 提交时间： 2023-06-06
摘要： β衰变半衰期和β延迟中子发射（βn）在核物理和核能等基础科学和工业应用的发展中具有重要意义，其中β−衰变起着重要作用。许多理论模型已经被提出来描述β-衰变的半衰期，而对βn的系统研究仍然很少。本文旨在通过解析公式研究了β−-衰减半衰期和βn概率，并与实验数据进行了比较。通过考虑衰减能量、凹凸度和壳效应等主要因素，提出了β−-衰减性质的解析公式。采用自助法同时评价计算的总不确定性，由统计量和系统不确定性组成。评估了中子富区的β−-衰变半衰期、βn概率和相应的不确定性。实验中的半衰期被很好地再现了。更多的预测也提出了理论的不确定性，这有助于更好地理解实验结果和理论结果之间的差异
分类： 心理学 >> 生理心理学 提交时间： 2021-02-09
摘要： Our current work examined the interface of thinking style and mental health at both behavioral and neuropsychological levels which describe a predisposition to psychopathology. Thirty-nine Chinese participants were divided into high and low holistic thinkers based on the triad task scores, completed the Sensitivity to Punishment and Sensitivity to Reward Questionnaire (SPSRQ), and performed structural and resting-state functional magnetic resonance imaging. We found that high holistic thinkers were much less sensitive to reward than low holistic thinkers. Furthermore, their bilateral nucleus accumbens and right amygdala volumes were smaller than those of low holistic thinkers. Our integrated results showed that the relationship between holistic thinking tendency and the amygdala volume was mediated by the nucleus accumbens and the sensitivity to reward. Finally, resting-state functional connectivity results showed increased FC between left nucleus accumbens and bilateral amygdala in high holistic thinkers. The present synthetical results suggest that dialectical thinking may lead to better mental health outcomes.
分类： 物理学 >> 核物理学 提交时间： 2016-09-12
摘要： Measurements of the fractional momentum loss (Sloss≡δpT/pT) of high-transverse-momentum-identified hadrons in heavy ion collisions are presented. Using π0 in Au+Au and Cu+Cu collisions at sNN−−−√=62.4 and 200 GeV measured by the PHENIX experiment at the Relativistic Heavy Ion Collider and and charged hadrons in Pb+Pb collisions measured by the ALICE experiment at the Large Hadron Collider, we studied the scaling properties of Sloss as a function of a number of variables: the number of participants, Npart, the number of quark participants, Nqp, the charged-particle density, dNch/dη, and the Bjorken energy density times the equilibration time, εBjτ0. We find that the pT where Sloss has its maximum, varies both with centrality and collision energy. Above the maximum, Sloss tends to follow a power-law function with all four scaling variables. The data at sNN−−−√=200 GeV and 2.76 TeV, for sufficiently high particle densities, have a common scaling of Sloss with dNch/dη and εBjτ0, lending insight on the physics of parton energy loss.
分类： 生物学 >> 生物物理学 提交时间： 2016-05-15
Zhang, Shaodan
Zhang, Chun
Zhang, Shaodan
Wang, Bo
Zhu, SenHua
Xie, Yuan
Qing, Guoping
Wang, Ningli
Thomas, Ravi
Thomas, Ravi
摘要： PURPOSE. To assess the cortical structure and cerebral blood flow changes in the brain of patients with primary open-angle glaucoma (POAG). METHODS. High-resolution anatomical magnetic resonance imaging (MRI) and arterial spin labeling (ASL)-MRI were performed in 23 POAG patients and 29 controls. Patients were further divided into early-moderate and advanced groups based on mean deviation (MD) cutoff of 12 dB. A baseline scan was obtained and repeated during visual stimulation to the central preserved visual field in the more affected eye of POAG patients and a randomly selected eye of controls. Gray matter volume (GMV) and cerebral blood flow (CBF) throughout the whole brain were compared between patients and controls. RESULTS. Compared to controls, a region with significant reduction of GMV was detected in the anterior calcarine fissure of advanced POAG patients (P < 0.001, voxels = 503, 1698 mm3). Patients with early-moderate POAG had resting CBF similar to that of controls. However, a region with marked CBF decrease was detected in the anterior calcarine fissure of advanced POAG patients (P < 0.001, voxels = 1687, 13,496 mm(3)). The region with CBF reduction in advanced POAG showed good colocalization with the region with GMV decrease in this group. Following visual stimulation, patients with advanced POAG showed significantly lower increase in CBF in the occipital lobes (P < 0.001, voxels = 112, 896 mm(3)) as compared to controls (P < 0.001, voxels = 1880, 15,040 mm(3)) and early-moderate POAG (P < 0.001, voxels = 2233, 17,864 mm(3)). CONCLUSIONS. Primary open-angle glaucoma patients demonstrate a disease severity-dependent retinotopic pattern of cortical atrophy and CBF abnormalities in the visual cortex. Cerebral blood flow may be a potential biomarker for the brain involvement in glaucoma.
分类： 生物学 >> 生物物理学 提交时间： 2016-05-12
摘要： Vesicle recycling is pivotal for maintaining reliable synaptic signaling, but its basic properties remain poorly understood. Here, we developed an approach to quantitatively analyze the kinetics of vesicle recycling with exquisite signal and temporal resolution at the calyx of Held synapse. The combination of this electrophysiological approach with electron microscopy revealed that similar to 80% of vesicles (similar to 270,000 out of similar to 330,000) in the nerve terminal are involved in recycling. Under sustained stimulation, recycled vesicles start to be reused in tens of seconds when similar to 47% of the preserved vesicles in the recycling pool (RP) are depleted. The heterogeneity of vesicle recycling as well as two kinetic components of RP depletion revealed the existence of a replenishable pool of vesicles before the priming stage and led to a realistic kinetic model that assesses the size of the subpools of the RP. Thus, our study quantified the kinetics of vesicle recycling and kinetically dissected the whole vesicle pool in the calyceal terminal into the readily releasable pool (similar to 0.6%), the readily priming pool (similar to 46%), the premature pool (similar to 33%), and the resting pool (similar to 20%).
分类： 生物学 >> 生物物理学 提交时间： 2016-05-12
Wen, Wen
Liu, Tingting
Zhang, Ting
Sun, Xinghuai
Wen, Wen
Sun, Xinghuai
Wen, Wen
Sun, Xinghuai
Zhang, Peng
He, Sheng
Gao, Jian
Sun, Xinghuai
He, Sheng
摘要： PURPOSE. This study investigated a novel motion-on-color paradigm to functionally isolate the magnocellular pathway and evaluate its diagnostic value in preperimetric glaucoma patients. METHODS. Thirty patients with preperimetric primary open-angle glaucoma and 30 controls participated in this study. They were tested in both the foveal and peripheral locations. Contrast sensitivity was assessed for the direction discrimination of a moving luminance-modulated grating presented on top of a red/green isoluminant grating. The moving test grating was designed to target the magnocellular pathway, while the background red/green isoluminant grating was designed to saturate the parvocellular pathway. The luminance-modulated grating was presented at spatial frequency of 0.5 cyc/deg, moving horizontally at four temporal frequencies (3 Hz, 8 Hz, 15 Hz, 25 Hz). Participants were asked to indicate the direction of motion for the luminance grating. As a comparison condition, frequency-doubling stimuli were also presented in the periphery and participants were asked to detect the occurrence of the frequency-doubled pattern. Two-way repeated-measures analysis of variance was performed with temporal frequency modulations as within-subject factor and group as between-subject factor, while contrast sensitivity was the dependent variable. Receiver operating characteristic (ROC) analysis was used to characterize diagnostic performance of the new procedure in comparison with the frequency-doubling tests for preperimetric glaucoma. RESULTS. The contrast sensitivity function in both the fovea and the periphery showed an inverted "V" shape with highest sensitivity in the intermediate temporal frequencies, consistent with physiological properties of the magnocellular pathway. At the fovea, compared to the control group, the sensitivity for the glaucoma patients was slightly but not significantly reduced (P > 0.05), and there was no significant interaction between groups and temporal frequency (P > 0.05). In the periphery, patients' sensitivity was significantly lower (P < 0.001) than that of normal participants, especially in high temporal frequencies, as supported by a statistically significant interaction between groups and temporal frequency (P < 0.001). The areas under ROC curves (AUROC) obtained for the motion-on-color paradigm in the periphery were 0.957 (25 Hz), 0.870 (15 Hz), 0.758 (8 Hz), and 0.561 (3 Hz) and were 0.761 for the traditional frequency-doubling test. CONCLUSIONS. The motion-on-color paradigm revealed a loss of contrast sensitivity in the peripheral visual field in preperimetric glaucoma. When applied with stimuli at high temporal frequency, the new paradigm had higher diagnostic sensitivity and specificity than the traditional frequency-doubling test. The findings also support the viewpoint that selective evaluation of magnocellular pathway function could facilitate the earlier detection of functional defects in glaucoma before visual field defects by standard perimetry.
分类： 生物学 >> 生物物理学 >> 生物物理、生物化学与分子生物学 提交时间： 2016-05-11
Liu Ying
Mo Wei-Chuan
Fu Jing-Peng
Liu Ying
He Rong-Qiao
Fu Jing-Peng
Liu Ying
He Rong-Qiao
Ding Hai-Min
Hua Qian
摘要： It has been established that exposure in the hypomagnetic field (HMF), which is one of the environmental factor of outer space, has adverse effects on animal and human behavior and brain function. Thus, it is necessary to develop appropriate counteract strategy to avoid the HMF-induced risks to the health of the astronauts during long-term and long-distance manned space mission. However, the physical and mental effects of the HMF in details still await systematic evaluation and the underlying mechanism remains elusive, so far. In this study, we constructed an HMF animal rearing system (<500 nT) and examined the effects of one-month HMF exposure on the circadian behavior, pain response and emotions in adult male C57BL/6 mice (4 similar to 6 weeks old, (20 +/- 2) g). The control animals were reared in the geomagnetic field (GMF). The HMF-exposed animals exhibited a prolonged alteration of the circadian drinking rhythm and a decrease in general activity, accompanied with an increase in thermal hyperalgesia. But the HMF did not induce obvious depression-like and anxiety-related behaviors. The serum noradrenalin concentration in HMF-exposed mice significantly decreased. These findings indicate that the HMF disturbs the behavior rhythm and the function of endocrine system, which probably leads to the subsequently weakened activities of the animal.
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