We investigate the impact of high-energy O ions on the occurrence of single-event burnout(SEB) in silicon carbide(Si C) metal–oxide–semiconductor field-effect transistors(MOSFETs) under various bias conditions. Thro...We investigate the impact of high-energy O ions on the occurrence of single-event burnout(SEB) in silicon carbide(Si C) metal–oxide–semiconductor field-effect transistors(MOSFETs) under various bias conditions. Through a combination of SRIM, GEANT4, and TCAD simulations, we explore the role of secondary ions generated by nuclear reactions between high-energy O ions and Si C materials. These secondary ions, with significantly higher linear energy transfer(LET) values, contribute to electron–hole pair generation, leading to SEB. Our results show that the energy deposition and penetration depth of these secondary ions, especially those with high LET, are sufficient to induce catastrophic SEB in Si C MOSFETs. The study also highlights the critical influence of reverse bias voltage on SEB occurrence and provides insights into the failure mechanisms induced by nuclear reactions with high-energy O ions. This work offers valuable understanding for improving the radiation resistance of Si C-based power devices used in space and high-radiation environments,contributing to the design of more reliable electronics for future space missions.展开更多
This paper reports on an experiment for testing natural nuclear fusion at low temperature searching for evidence of the origin of 3He from natural nuclear fusion in deep Earth. The experiment was carried out using deu...This paper reports on an experiment for testing natural nuclear fusion at low temperature searching for evidence of the origin of 3He from natural nuclear fusion in deep Earth. The experiment was carried out using deuterium-loaded titanium foil samples and powder sample. Detection of charged particle was carried out using a low-level charged particle spectrometer. An A1 foil was used as an energy absorber for identification of charged particle. Although the counting rate is very low in the experiment, the emission of energetic particle from the sample is observed and the particle is identified as a proton having energy about 2.8 MeV after exiting the titanium sample. This work provides a positive result for the emission of charged particle in the deuterium-loaded titanium foil samples at low temperature, but a negative result for the deuterium-loaded titanium powder sample. The average reaction yield is deduced to be （0.46±0.08） protons/h for the foil samples. With the suggestion that the proton originates from d-d reaction, we calculate the reaction rate for d-d reaction, and the obtained result is 1.4×10^-24 fusion/d-d.sec. The negative result of the deuterium-loaded titanium powder sample suggests that the reaction yield might be correlated with the density or microscopic variables of deuterium-loaded titanium materials. The negative result also indicates that d-d reaction catalysed by μ-meson from cosmic ray can be excluded in the samples in this experiment.展开更多
Tritium （3^H） in excess of the atmospheric values was found at volcanic Lakes Pavin （France）, Laacher （Germany） and Nemrut （Turkey）, as well as Kilauea Volcano at Hawaii （USA） and other volcanoes. Because 3^...Tritium （3^H） in excess of the atmospheric values was found at volcanic Lakes Pavin （France）, Laacher （Germany） and Nemrut （Turkey）, as well as Kilauea Volcano at Hawaii （USA） and other volcanoes. Because 3^H has a short half-life of 12.3 years, the tritium and the resulting 3^He must have formed recently in the Earth. The result suggests that nuclear reactions may generate a significant amount of tritium in the interior of the Earth, although we have not yet learned what the reaction mechanism may be responsible. The nuclear reaction that can be responsible for tritium production in the Earth is probably a new research field in physics science. Nuclear reactions that generate tritium might be a source of ＂missing＂ energy （heat） in the interior of the Earth. Finding in-situ 3^H in the mantle may exhibit an alternative explanation of 3^He origin in the deep Earth.展开更多
The sigma meson production in p ＋ ^12C and p A- ^40Ca reactions at the incident energy Ep = 1.5 GeV is investigated within the Quantum Molecular Dynamics model. The simulation results indicate a distinctive A depende...The sigma meson production in p ＋ ^12C and p A- ^40Ca reactions at the incident energy Ep = 1.5 GeV is investigated within the Quantum Molecular Dynamics model. The simulation results indicate a distinctive A dependence of the sigma production, that is, the increase of A is followed by an increase of the production cross sections. We find that the σ meson production in proton-induced reactions is strongly medium-dependent, and the produced σ mesons decaying in a denser medium experience a stronger mass shift towards lower masses. This mass shift is an experimentally accessible observable in the final state pion pairs, which do not suffer from reabsorption by the surrounding nucleons. It is pointed out that the ratio of measured sigma cross sections as a function of the sigma invariant-mass from various reactions is a good probe to explore the existence of the σ meson in a dense nuclear environment.展开更多
Based on the theory of relativistic superstrong magnetic fields （SMFs）, by using the method of Thomas-Fermi-Dirac approximations, we investigate the problem of strong electron screening （SES） in SMFs and the influ...Based on the theory of relativistic superstrong magnetic fields （SMFs）, by using the method of Thomas-Fermi-Dirac approximations, we investigate the problem of strong electron screening （SES） in SMFs and the influence of SES on the nuclear reaction of 23Mg （p, Y）24A1. Our calculations show that the nuclear reaction will be markedly effected by the SES in SMFs in the surface of magnetars. Our calculated screening rates can increase two orders of magnitude due to SES in SMFs.展开更多
The coupling of the sun's gravitational field with processes of diffusion and convection exerts a significant influence on the dynamical behavior of the core 3He nuclear reaction-diffusion system. Stability analys...The coupling of the sun's gravitational field with processes of diffusion and convection exerts a significant influence on the dynamical behavior of the core 3He nuclear reaction-diffusion system. Stability analyses of the system are made in this paper by using the theory of nonequilibrium dynamics. It is showed that, in the nuclear reaction regions extending from the center to about 0.38 times of the radius of the sun, the gravitational field enables the core 3He nuclear reaction-diffusion system to become unstable and, after the instability, new states to appear in the system have characteristic of time oscillation. This may change the production rates of both 7Be and 8B neutrinos.展开更多
A 13.4 MeV deuteron beam from the 1.2 meter cyclotron of Sichuan University was used to determine theprotein content in wheat seeds on the basis of (d,p) reactions. The influence of the variation of the water content ...A 13.4 MeV deuteron beam from the 1.2 meter cyclotron of Sichuan University was used to determine theprotein content in wheat seeds on the basis of (d,p) reactions. The influence of the variation of the water content inseeds has been investigated.展开更多
Titanium is one of the best hydrogen loading material. The pre dieted maximum loading ratio of hydrogen in titanium may reach to 2.0. In this work, a titanium layer on molybdenum substrate was deuterated with the atom...Titanium is one of the best hydrogen loading material. The pre dieted maximum loading ratio of hydrogen in titanium may reach to 2.0. In this work, a titanium layer on molybdenum substrate was deuterated with the atomic: ratio X =2H/Ti≥1.6. The change of the surface topography and rnicrostructurc of the sample before and after loading was observed by using Scan Electron Microscopy (SEM). The surface segregation of the samples after deutcron bombardment was also observed. A fluctuatingly-incrcasing trend of the deutcriuin density in titanium target was detected in the deuteron implantation experiments. which indicated a suddenly explosion (segregation) or fast diffusion of deuterium in the titanium. Significant amount of nitrogen contamination was found in thc Ti2Hx sample by nuclear reaction analysis (NRA), which indicated that the Ti2Hx structure might have the feature to trap nitrogen from air. The nitrogen contamination in Ti2Hx significantly affects the increase of the atomic ratio X展开更多
The work has the characters of a philosophical note, in which a new exotic version of the atom structure is discussed. According to this, the atomic nucleus consists of “normal” and “special” neutrons. Electrons a...The work has the characters of a philosophical note, in which a new exotic version of the atom structure is discussed. According to this, the atomic nucleus consists of “normal” and “special” neutrons. Electrons are internal part of both types of neutron. Electrons can leave “normal” neutrons of the nucleus and return back with a certain probability. These processes lead to the appearance of protons in the nucleus and form the electron orbits of the atom. At the same time, it is possible that the Coulomb’s barriers of atoms and nucleus disappear at some point in time and cold nuclear reactions pass through. This assumption leads to a new exotic model of the Universe structure, namely, the existence of neutron ether, consisting of special neutrons that do not emit their own electrons. In this ethereal ocean of special neutrons, periodically provoked disturbances arise. After that, it creates pockets, clusters of our normal neutrons inherent in our world, which can already emit electrons and, consequently, create atoms. The ether gets sick from time to time. However, as a result of this disease, stars arise. Some possible stages in the creation of our world are also discussed in this paper.展开更多
The present manuscript investigates the fusion-ER cross-sections of different projectile-target combinations,namely,^(16)O+^(148,150)Nd,^(165)Ho,^(194)Pt,^(18)O+^(148)Nd,^(194)Pt,^(192)Os,^(19)F+^(188)s,and^(30)Si+^(1...The present manuscript investigates the fusion-ER cross-sections of different projectile-target combinations,namely,^(16)O+^(148,150)Nd,^(165)Ho,^(194)Pt,^(18)O+^(148)Nd,^(194)Pt,^(192)Os,^(19)F+^(188)s,and^(30)Si+^(170)Er,consisting of quadrupole(β_(2))and hexadecapole(β_(4))deformed target nuclei.The study analyzes the influence of higher-order deformations and corresponding orientation criteria adopted for the exploration of the dynamics of the considered nuclei.The influence of these parameters has been studied in terms of capture cross-section(σ_(cap)),compound nucleus(CN)formation probability(P_(CN)),survival probability(W_(sur)),and the fusion-ER cross-sections across center of mass energies(E_(c.m.)).The study recognizes the importance of the fission barrier in determining the survival probability(W_(sur))of the compound nucleus and subsequently the ER cross-sections.A discrepancy among the calculated and experimental ER cross-sections is observed,particularly in reactions with lower fission barriers.In reactions with a lower fission barrier of formed CN,the level density parameter ratio(a_(f)/a_(n))of the fission and neutron-evaporation channels assists in the study of experimental data.展开更多
The effects of nucleon-nucleon short-range correlations leading to the high-momentum tail(HMT)in the nucleon momentum distribution are studied using the iso spin-and momentum-dependent Lanzhou quantum molecular dynami...The effects of nucleon-nucleon short-range correlations leading to the high-momentum tail(HMT)in the nucleon momentum distribution are studied using the iso spin-and momentum-dependent Lanzhou quantum molecular dynamics(LQMD)transport model.Based on the transport model,we study the effects of the HMT of the nucleon momentum distribution on initialization in isotopic nuclear reactions at a beam energy of 120 MeV/u.The single and double ratios of gas-phase neutron and proton spectra are analyzed and compared with experimental data in central ^(112)Sn+^(112)Sn and^(124)Sn+^(124)Sn collisions.The HMT affects the single ratios but not the double ratios,which can be employed to study other iso spin effects more effectively.The ratio of triton to 3 He of light clusters contained in the gas-phase nucleons is also influenced by the HMT.Combining the QMD transport model that can describe multifragmentation and the production of fragments in intermediate-energy heavy-ion collisions,we study the short-range correlation effect on fragment generation.We find that the iso spin-dependent HMT significantly affects the fragment multiplicity distribution and average neutron-to-proton ratio of produced isobars.展开更多
The Glauber/eikonal model is a widely used tool for studying intermediate-and high-energy nuclear reactions.When calculating the Glauber/eikonal model phase shift functions,the optical limit approximation(OLA)is often...The Glauber/eikonal model is a widely used tool for studying intermediate-and high-energy nuclear reactions.When calculating the Glauber/eikonal model phase shift functions,the optical limit approximation(OLA)is often used.The OLA neglects the multiple scattering of the constituent nucleons in the projectile and target nuclei.However,the nucleon-target version of the Glauber model(the NTG model)proposed by Abu-Ibrahim and Suzuki includes multiple scattering effects between the projectile nucleons and target nuclei.The NTG model was found to improve the description of the elastic scattering angular distributions and total reaction cross sections of some light heavy-ion systems with respect to the OLA.In this work,we study the single-nucleon removal reactions(SNRRs)induced by carbon isotopes on ^(12)C and ^(9)Be targets using both the NTG model and the OLA.Reduction factors(RFs)of the single-nucleon spectroscopic factors were obtained by comparing the experimental and theoretical SNRR cross sections.On average,the RFs obtained with the NTG model were smaller than those obtained using the OLA by 7.8%,in which the average difference in one-neutron removal was 10.6% and that in one-proton removal was 4.2%.However,the RFs were still strongly dependent on the neutron-proton asymmetryΔS of the projectile nuclei,even when the NTG model was used.展开更多
Driving of the nuclear fusion reaction p+^(11)B3α+8.7 MeV under laboratory conditions by interaction between high-power laser pulses and matter has become a popular field of research,owing to its numerous potential a...Driving of the nuclear fusion reaction p+^(11)B3α+8.7 MeV under laboratory conditions by interaction between high-power laser pulses and matter has become a popular field of research,owing to its numerous potential applications:as an alternative to deuterium-tritium for fusion energy production,astrophysics studies,and alpha-particle generation for medical treatment.One possible scheme for laser-driven p-^(11)B reactions is to direct a beam of laser-accelerated protons onto a boron(B)sample(the so-called“pitcher-catcher”scheme).This technique has been successfully implemented on large high-energy lasers,yielding hundreds of joules per shot at low repetition.We present here a complementary approach,exploiting the high repetition rate of the VEGA III petawatt laser at CLPU(Spain),aiming at accumulating results from many interactions at much lower energy,to provide better control of the parameters and the statistics of the measurements.Despite a moderate energy per pulse,our experiment allowed exploration of the laser-driven fusion process with tens(up to hundreds)of laser shots.The experiment provided a clear signature of the reactions involved and of the fusion products,accumulated over many shots,leading to an improved optimization of the diagnostics for experimental campaigns of this type.In this paper,we discuss the effectiveness of laser-driven p-11B fusion in the pitcher-catcher scheme,at a high repetition rate,addressing the challenges of this experimental scheme and highlighting its critical aspects.Our proposed methodology allows evaluation of the performance of this scheme for laser-driven alpha particle production and can be adapted to high-repetition-rate laser facilities with higher energy and intensity.展开更多
Fusion hindrance in the radial degree of freedom for massive nuclear reactions is known for a long time. However the present work shows that the fusion hindrance also exists in the neck evolution. We calculate the pot...Fusion hindrance in the radial degree of freedom for massive nuclear reactions is known for a long time. However the present work shows that the fusion hindrance also exists in the neck evolution. We calculate the potential at different distances and different neck parameters by the two-center liquid drop model and then check whether fusion hindrance exists in the neck evolution by examing the sign of slope of potential vs. the neck parameter. The area of fusion hindrance in the neck evolution is shown.展开更多
To ensure agreement between theoretical calculations and experimental data,parameters to selected nuclear physics models are perturbed and fine-tuned in nuclear data evaluations.This approach assumes that the chosen s...To ensure agreement between theoretical calculations and experimental data,parameters to selected nuclear physics models are perturbed and fine-tuned in nuclear data evaluations.This approach assumes that the chosen set of models accurately represents the‘true’distribution of considered observables.Furthermore,the models are chosen globally,indicating their applicability across the entire energy range of interest.However,this approach overlooks uncertainties inherent in the models themselves.In this work,we propose that instead of selecting globally a winning model set and proceeding with it as if it was the‘true’model set,we,instead,take a weighted average over multiple models within a Bayesian model averaging(BMA)framework,each weighted by its posterior probability.The method involves executing a set of TALYS calculations by randomly varying multiple nuclear physics models and their parameters to yield a vector of calculated observables.Next,computed likelihood function values at each incident energy point were then combined with the prior distributions to obtain updated posterior distributions for selected cross sections and the elastic angular distributions.As the cross sections and elastic angular distributions were updated locally on a per-energy-point basis,the approach typically results in discontinuities or“kinks”in the cross section curves,and these were addressed using spline interpolation.The proposed BMA method was applied to the evaluation of proton-induced reactions on ^(58)Ni between 1 and 100 MeV.The results demonstrated a favorable comparison with experimental data as well as with the TENDL-2023 evaluation.展开更多
Nuclear astrophysics is a rapidly developing interdisciplinary feld of research that has received extensive attention from the scientifc community since the midtwentieth century.Broadly,it uses the laws of extremely s...Nuclear astrophysics is a rapidly developing interdisciplinary feld of research that has received extensive attention from the scientifc community since the midtwentieth century.Broadly,it uses the laws of extremely small atomic nuclei to explain the evolution of the universe.Owing to the complexity of nucleosynthesis processes and our limited understanding of nuclear physics in astrophysical environments,several critical astrophysical problems remain unsolved.To achieve a better understanding of astrophysics,it is necessary to measure the cross sections of key nuclear reactions with the precision required by astrophysical models.Direct measurement of nuclear reaction cross sections is an important method of investigating how nuclear reactions infuence stellar evolution.Given the challenges involved in measuring the extremely low crosssections of nuclear reactions in the Gamow peak and preparing radioactive targets,indirect methods,such as the transfer reaction,coulomb dissociation,and surrogate ratio methods,have been developed over the past several decades.These are powerful tools in the investigation of,for example,neutron-capture(n,r)reactions with short-lived radioactive isotopes.However,direct measurement is still preferable,such as in the case of reactions involving light and stable nuclei.As an essential part of stellar evolution,these low-energy stable nuclear reactions have been of particular interest in recent years.To overcome the diffculties in measurements near or deeply within the Gamow window,the combination of an underground laboratory and high-exposure accelerator/detector complex is currently the optimal solution.Therefore,underground experiments have emerged as a new and promising direction of research.In addition,to better simulate the stellar environment in the laboratory,research on nuclear physics under laser-driven plasma conditions has gradually become a frontier hotspot.In recent years,the CIAE team conducted a series of distinctive nuclear astrophysics studies,relying on the Jinping Underground Nuclear Astrophysics platform and accelerators in Earth’s surface laboratories,including the Beijing Radioactive Ion beam Facility,as well as other scientifc platforms at home and abroad.This research covered nuclear theories,numerical models,direct measurements,indirect measurements,and other novel approaches,achieving great interdisciplinary research results,with high-level academic publications and signifcant international impacts.This article reviews the above research and predicts future developments.展开更多
Based on the relativistic theory of superstrong magnetic fields（SMF）, by using three models those of Lai（LD）, Fushiki（FGP）, and our own（LJ）, we investigate the influence of SMFs due to strong electron screenin...Based on the relativistic theory of superstrong magnetic fields（SMF）, by using three models those of Lai（LD）, Fushiki（FGP）, and our own（LJ）, we investigate the influence of SMFs due to strong electron screening（SES） on the nuclear reaction 23Mg（p,γ） 24Al in magnetars. In a relatively low density environment（e.g., ρ7 〈0.01）and 1 〈 B12 〈 102, our screening rates are in good agreement with those of LD and FGP. However, in relatively high magnetic fields（e.g., B12 〉102）, our reaction rates can be 1.58 times and about three orders of magnitude larger than those of FGP and LD, respectively（B12, ρ7 are in units of 1012G, 107 g cm-3）. The significant increase of strong screening rate can imply that more 23Mg will escape from the Ne-Na cycle due to SES in a SMF. As a consequence,the next reaction, 24Al（＋β, ν） 24Mg, will produce more 24Mg to participate in the Mg-Al cycle. Thus, it may lead to synthesis of a large amount of A〉20 nuclides in magnetars.展开更多
We study in the framework of the Langevin model the influence of initial excitation energy(E*) of Hg compound nuclei(CNs) on the sensitivity of the excitation energy at scission(Esc*) to the nuclear friction strength(...We study in the framework of the Langevin model the influence of initial excitation energy(E*) of Hg compound nuclei(CNs) on the sensitivity of the excitation energy at scission(Esc*) to the nuclear friction strength(β).It is shown that the sensitivity is enhanced substantially with increasing E*.Moreover,we find that the significant sensitivity of Esc* to β at high E*is little affected by a marked difference in the neutron-to-proton ratio of a CN and in its size and fissility.Our findings suggest that,on the experimental side,a measurement of Esc* in energetic proton-induced spallation reactions can provide not only a sensitive but also a robust probe of nuclear dissipation in fission of highly excited nuclei.Further development of a suitable approach to spallation reaction is discussed.展开更多
The theoretical cross section calculations for the astrophysical p process are needed because most of the related reactions are technically very difficult to be measured in the laboratory. Even if the reaction was mea...The theoretical cross section calculations for the astrophysical p process are needed because most of the related reactions are technically very difficult to be measured in the laboratory. Even if the reaction was measured,most of the measured reactions have been carried out at the higher energy range from the astrophysical energies.Therefore, almost all cross sections needed for p process simulation have to be theoretically calculated or extrapolated to the astrophysical energies.^(112)Sn(α,γ)^(116)Te is an important reaction for the p process nucleosynthesis. The theoretical cross section of ^(112)Sn(α,γ)^(116)Te reaction was investigated for different global optical model potentials,level density, and strength function models at the astrophysically interested energies. Astrophysical S factors were calculated and compared with experimental data available in the EXFOR database. The calculation with the optical model potential of the dispersive model by Demetriou et al., and the back-shifted Fermi gas level density model and Brink-Axel Lorentzian strength function model best served to reproduce experimental results at an astrophysically relevant energy region. The reaction rates were calculated with these model parameters at the p process temperature and compared with the current version of the reaction rate library Reaclib and Starlib.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 12035019 and 62234013)the National Key Research and Development Program of China(Grant Nos. 2023YFA1609000 and 2022YFB3604001)。
文摘We investigate the impact of high-energy O ions on the occurrence of single-event burnout(SEB) in silicon carbide(Si C) metal–oxide–semiconductor field-effect transistors(MOSFETs) under various bias conditions. Through a combination of SRIM, GEANT4, and TCAD simulations, we explore the role of secondary ions generated by nuclear reactions between high-energy O ions and Si C materials. These secondary ions, with significantly higher linear energy transfer(LET) values, contribute to electron–hole pair generation, leading to SEB. Our results show that the energy deposition and penetration depth of these secondary ions, especially those with high LET, are sufficient to induce catastrophic SEB in Si C MOSFETs. The study also highlights the critical influence of reverse bias voltage on SEB occurrence and provides insights into the failure mechanisms induced by nuclear reactions with high-energy O ions. This work offers valuable understanding for improving the radiation resistance of Si C-based power devices used in space and high-radiation environments,contributing to the design of more reliable electronics for future space missions.
基金Project supported by President Foundation of China Institute of Atomic Energy (Grant No YZ0714)
文摘This paper reports on an experiment for testing natural nuclear fusion at low temperature searching for evidence of the origin of 3He from natural nuclear fusion in deep Earth. The experiment was carried out using deuterium-loaded titanium foil samples and powder sample. Detection of charged particle was carried out using a low-level charged particle spectrometer. An A1 foil was used as an energy absorber for identification of charged particle. Although the counting rate is very low in the experiment, the emission of energetic particle from the sample is observed and the particle is identified as a proton having energy about 2.8 MeV after exiting the titanium sample. This work provides a positive result for the emission of charged particle in the deuterium-loaded titanium foil samples at low temperature, but a negative result for the deuterium-loaded titanium powder sample. The average reaction yield is deduced to be （0.46±0.08） protons/h for the foil samples. With the suggestion that the proton originates from d-d reaction, we calculate the reaction rate for d-d reaction, and the obtained result is 1.4×10^-24 fusion/d-d.sec. The negative result of the deuterium-loaded titanium powder sample suggests that the reaction yield might be correlated with the density or microscopic variables of deuterium-loaded titanium materials. The negative result also indicates that d-d reaction catalysed by μ-meson from cosmic ray can be excluded in the samples in this experiment.
基金supported by President Foundation of the China Institute of Atomic Energy (No.YZ-0704)
文摘Tritium （3^H） in excess of the atmospheric values was found at volcanic Lakes Pavin （France）, Laacher （Germany） and Nemrut （Turkey）, as well as Kilauea Volcano at Hawaii （USA） and other volcanoes. Because 3^H has a short half-life of 12.3 years, the tritium and the resulting 3^He must have formed recently in the Earth. The result suggests that nuclear reactions may generate a significant amount of tritium in the interior of the Earth, although we have not yet learned what the reaction mechanism may be responsible. The nuclear reaction that can be responsible for tritium production in the Earth is probably a new research field in physics science. Nuclear reactions that generate tritium might be a source of ＂missing＂ energy （heat） in the interior of the Earth. Finding in-situ 3^H in the mantle may exhibit an alternative explanation of 3^He origin in the deep Earth.
基金National Natural Science Foundation of China under Grant Nos.10435080,10575075,and 10447006the Deutsche Forschungsgemeinschaft under Grant No.446CHV-113/91/1-3the National Research Concil of Thailand under Grant No.1.CH5/2549
文摘The sigma meson production in p ＋ ^12C and p A- ^40Ca reactions at the incident energy Ep = 1.5 GeV is investigated within the Quantum Molecular Dynamics model. The simulation results indicate a distinctive A dependence of the sigma production, that is, the increase of A is followed by an increase of the production cross sections. We find that the σ meson production in proton-induced reactions is strongly medium-dependent, and the produced σ mesons decaying in a denser medium experience a stronger mass shift towards lower masses. This mass shift is an experimentally accessible observable in the final state pion pairs, which do not suffer from reabsorption by the surrounding nucleons. It is pointed out that the ratio of measured sigma cross sections as a function of the sigma invariant-mass from various reactions is a good probe to explore the existence of the σ meson in a dense nuclear environment.
基金supported in part by the National Natural Science Foundation of China through grant No. 11565020the Natural Science Foundation of Hainan province under grant No. 114012the Undergraduate Innovation Program of Hainan province under grant No. 20130139
文摘Based on the theory of relativistic superstrong magnetic fields （SMFs）, by using the method of Thomas-Fermi-Dirac approximations, we investigate the problem of strong electron screening （SES） in SMFs and the influence of SES on the nuclear reaction of 23Mg （p, Y）24A1. Our calculations show that the nuclear reaction will be markedly effected by the SES in SMFs in the surface of magnetars. Our calculated screening rates can increase two orders of magnitude due to SES in SMFs.
文摘The coupling of the sun's gravitational field with processes of diffusion and convection exerts a significant influence on the dynamical behavior of the core 3He nuclear reaction-diffusion system. Stability analyses of the system are made in this paper by using the theory of nonequilibrium dynamics. It is showed that, in the nuclear reaction regions extending from the center to about 0.38 times of the radius of the sun, the gravitational field enables the core 3He nuclear reaction-diffusion system to become unstable and, after the instability, new states to appear in the system have characteristic of time oscillation. This may change the production rates of both 7Be and 8B neutrinos.
文摘A 13.4 MeV deuteron beam from the 1.2 meter cyclotron of Sichuan University was used to determine theprotein content in wheat seeds on the basis of (d,p) reactions. The influence of the variation of the water content inseeds has been investigated.
基金Supported by a fund of the Chinese Academy of Sciences the special fund of the Nuclear Power Institute of China
文摘Titanium is one of the best hydrogen loading material. The pre dieted maximum loading ratio of hydrogen in titanium may reach to 2.0. In this work, a titanium layer on molybdenum substrate was deuterated with the atomic: ratio X =2H/Ti≥1.6. The change of the surface topography and rnicrostructurc of the sample before and after loading was observed by using Scan Electron Microscopy (SEM). The surface segregation of the samples after deutcron bombardment was also observed. A fluctuatingly-incrcasing trend of the deutcriuin density in titanium target was detected in the deuteron implantation experiments. which indicated a suddenly explosion (segregation) or fast diffusion of deuterium in the titanium. Significant amount of nitrogen contamination was found in thc Ti2Hx sample by nuclear reaction analysis (NRA), which indicated that the Ti2Hx structure might have the feature to trap nitrogen from air. The nitrogen contamination in Ti2Hx significantly affects the increase of the atomic ratio X
文摘The work has the characters of a philosophical note, in which a new exotic version of the atom structure is discussed. According to this, the atomic nucleus consists of “normal” and “special” neutrons. Electrons are internal part of both types of neutron. Electrons can leave “normal” neutrons of the nucleus and return back with a certain probability. These processes lead to the appearance of protons in the nucleus and form the electron orbits of the atom. At the same time, it is possible that the Coulomb’s barriers of atoms and nucleus disappear at some point in time and cold nuclear reactions pass through. This assumption leads to a new exotic model of the Universe structure, namely, the existence of neutron ether, consisting of special neutrons that do not emit their own electrons. In this ethereal ocean of special neutrons, periodically provoked disturbances arise. After that, it creates pockets, clusters of our normal neutrons inherent in our world, which can already emit electrons and, consequently, create atoms. The ether gets sick from time to time. However, as a result of this disease, stars arise. Some possible stages in the creation of our world are also discussed in this paper.
文摘The present manuscript investigates the fusion-ER cross-sections of different projectile-target combinations,namely,^(16)O+^(148,150)Nd,^(165)Ho,^(194)Pt,^(18)O+^(148)Nd,^(194)Pt,^(192)Os,^(19)F+^(188)s,and^(30)Si+^(170)Er,consisting of quadrupole(β_(2))and hexadecapole(β_(4))deformed target nuclei.The study analyzes the influence of higher-order deformations and corresponding orientation criteria adopted for the exploration of the dynamics of the considered nuclei.The influence of these parameters has been studied in terms of capture cross-section(σ_(cap)),compound nucleus(CN)formation probability(P_(CN)),survival probability(W_(sur)),and the fusion-ER cross-sections across center of mass energies(E_(c.m.)).The study recognizes the importance of the fission barrier in determining the survival probability(W_(sur))of the compound nucleus and subsequently the ER cross-sections.A discrepancy among the calculated and experimental ER cross-sections is observed,particularly in reactions with lower fission barriers.In reactions with a lower fission barrier of formed CN,the level density parameter ratio(a_(f)/a_(n))of the fission and neutron-evaporation channels assists in the study of experimental data.
基金Supported by the National Natural Science Foundation of China(12305130)China Postdoctoral Science Foundation(2023M731016)+1 种基金Henan Postdoctoral Foundation(HN2022164)the Natural Science Foundation of Henan Province(242300422048)。
文摘The effects of nucleon-nucleon short-range correlations leading to the high-momentum tail(HMT)in the nucleon momentum distribution are studied using the iso spin-and momentum-dependent Lanzhou quantum molecular dynamics(LQMD)transport model.Based on the transport model,we study the effects of the HMT of the nucleon momentum distribution on initialization in isotopic nuclear reactions at a beam energy of 120 MeV/u.The single and double ratios of gas-phase neutron and proton spectra are analyzed and compared with experimental data in central ^(112)Sn+^(112)Sn and^(124)Sn+^(124)Sn collisions.The HMT affects the single ratios but not the double ratios,which can be employed to study other iso spin effects more effectively.The ratio of triton to 3 He of light clusters contained in the gas-phase nucleons is also influenced by the HMT.Combining the QMD transport model that can describe multifragmentation and the production of fragments in intermediate-energy heavy-ion collisions,we study the short-range correlation effect on fragment generation.We find that the iso spin-dependent HMT significantly affects the fragment multiplicity distribution and average neutron-to-proton ratio of produced isobars.
基金financially supported by the National Key R&D Program of China(No.2023YFA1606702)the National Natural Science Foundation of China(Nos.U2067205 and 12205098).
文摘The Glauber/eikonal model is a widely used tool for studying intermediate-and high-energy nuclear reactions.When calculating the Glauber/eikonal model phase shift functions,the optical limit approximation(OLA)is often used.The OLA neglects the multiple scattering of the constituent nucleons in the projectile and target nuclei.However,the nucleon-target version of the Glauber model(the NTG model)proposed by Abu-Ibrahim and Suzuki includes multiple scattering effects between the projectile nucleons and target nuclei.The NTG model was found to improve the description of the elastic scattering angular distributions and total reaction cross sections of some light heavy-ion systems with respect to the OLA.In this work,we study the single-nucleon removal reactions(SNRRs)induced by carbon isotopes on ^(12)C and ^(9)Be targets using both the NTG model and the OLA.Reduction factors(RFs)of the single-nucleon spectroscopic factors were obtained by comparing the experimental and theoretical SNRR cross sections.On average,the RFs obtained with the NTG model were smaller than those obtained using the OLA by 7.8%,in which the average difference in one-neutron removal was 10.6% and that in one-proton removal was 4.2%.However,the RFs were still strongly dependent on the neutron-proton asymmetryΔS of the projectile nuclei,even when the NTG model was used.
基金funded by the European Union via the Euratom Research and Training Program(Grant Agreement No.101052200-EUROfusion)funding from LASERLAB-EUROPE(Grant Agreement No.871124,European Union’s Horizon 2020 Research and Innovation Program)+5 种基金supported in part by the United States Department of Energy under Grant No.DE-FG02-93ER40773We also acknowledge support from Grant No.PID2021-125389OA-I00 funded by MCIN/AEI/10.13039/501100011033/FEDER,UEby“ERDF A Way of Making Europe”by the European Union and Unidad de Investigación Consolidada of Junta de Castilla y León UIC 167supported in part by the National Natural Science Foundation of China under Grant No.12375125the Fundamental Research Funds for the Central Universitiesthe support of the Czech Science Foundation through Grant No.GACR24-11398S.
文摘Driving of the nuclear fusion reaction p+^(11)B3α+8.7 MeV under laboratory conditions by interaction between high-power laser pulses and matter has become a popular field of research,owing to its numerous potential applications:as an alternative to deuterium-tritium for fusion energy production,astrophysics studies,and alpha-particle generation for medical treatment.One possible scheme for laser-driven p-^(11)B reactions is to direct a beam of laser-accelerated protons onto a boron(B)sample(the so-called“pitcher-catcher”scheme).This technique has been successfully implemented on large high-energy lasers,yielding hundreds of joules per shot at low repetition.We present here a complementary approach,exploiting the high repetition rate of the VEGA III petawatt laser at CLPU(Spain),aiming at accumulating results from many interactions at much lower energy,to provide better control of the parameters and the statistics of the measurements.Despite a moderate energy per pulse,our experiment allowed exploration of the laser-driven fusion process with tens(up to hundreds)of laser shots.The experiment provided a clear signature of the reactions involved and of the fusion products,accumulated over many shots,leading to an improved optimization of the diagnostics for experimental campaigns of this type.In this paper,we discuss the effectiveness of laser-driven p-11B fusion in the pitcher-catcher scheme,at a high repetition rate,addressing the challenges of this experimental scheme and highlighting its critical aspects.Our proposed methodology allows evaluation of the performance of this scheme for laser-driven alpha particle production and can be adapted to high-repetition-rate laser facilities with higher energy and intensity.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10979024, 10905021, and 10979023)the Key Project of Science and Technology Research of the Ministry of Education of China (Grant No. 209053)the Natural Science Foundation of Zhejiang Province, China (Grant No. Y6090210)
文摘Fusion hindrance in the radial degree of freedom for massive nuclear reactions is known for a long time. However the present work shows that the fusion hindrance also exists in the neck evolution. We calculate the potential at different distances and different neck parameters by the two-center liquid drop model and then check whether fusion hindrance exists in the neck evolution by examing the sign of slope of potential vs. the neck parameter. The area of fusion hindrance in the neck evolution is shown.
基金funding from the Paul ScherrerInstitute,Switzerland through the NES/GFA-ABE Cross Project。
文摘To ensure agreement between theoretical calculations and experimental data,parameters to selected nuclear physics models are perturbed and fine-tuned in nuclear data evaluations.This approach assumes that the chosen set of models accurately represents the‘true’distribution of considered observables.Furthermore,the models are chosen globally,indicating their applicability across the entire energy range of interest.However,this approach overlooks uncertainties inherent in the models themselves.In this work,we propose that instead of selecting globally a winning model set and proceeding with it as if it was the‘true’model set,we,instead,take a weighted average over multiple models within a Bayesian model averaging(BMA)framework,each weighted by its posterior probability.The method involves executing a set of TALYS calculations by randomly varying multiple nuclear physics models and their parameters to yield a vector of calculated observables.Next,computed likelihood function values at each incident energy point were then combined with the prior distributions to obtain updated posterior distributions for selected cross sections and the elastic angular distributions.As the cross sections and elastic angular distributions were updated locally on a per-energy-point basis,the approach typically results in discontinuities or“kinks”in the cross section curves,and these were addressed using spline interpolation.The proposed BMA method was applied to the evaluation of proton-induced reactions on ^(58)Ni between 1 and 100 MeV.The results demonstrated a favorable comparison with experimental data as well as with the TENDL-2023 evaluation.
基金National Natural Science Foundation of China(Nos.12435010)National Key R&D Program of China(No.2022YFA1602301)。
文摘Nuclear astrophysics is a rapidly developing interdisciplinary feld of research that has received extensive attention from the scientifc community since the midtwentieth century.Broadly,it uses the laws of extremely small atomic nuclei to explain the evolution of the universe.Owing to the complexity of nucleosynthesis processes and our limited understanding of nuclear physics in astrophysical environments,several critical astrophysical problems remain unsolved.To achieve a better understanding of astrophysics,it is necessary to measure the cross sections of key nuclear reactions with the precision required by astrophysical models.Direct measurement of nuclear reaction cross sections is an important method of investigating how nuclear reactions infuence stellar evolution.Given the challenges involved in measuring the extremely low crosssections of nuclear reactions in the Gamow peak and preparing radioactive targets,indirect methods,such as the transfer reaction,coulomb dissociation,and surrogate ratio methods,have been developed over the past several decades.These are powerful tools in the investigation of,for example,neutron-capture(n,r)reactions with short-lived radioactive isotopes.However,direct measurement is still preferable,such as in the case of reactions involving light and stable nuclei.As an essential part of stellar evolution,these low-energy stable nuclear reactions have been of particular interest in recent years.To overcome the diffculties in measurements near or deeply within the Gamow window,the combination of an underground laboratory and high-exposure accelerator/detector complex is currently the optimal solution.Therefore,underground experiments have emerged as a new and promising direction of research.In addition,to better simulate the stellar environment in the laboratory,research on nuclear physics under laser-driven plasma conditions has gradually become a frontier hotspot.In recent years,the CIAE team conducted a series of distinctive nuclear astrophysics studies,relying on the Jinping Underground Nuclear Astrophysics platform and accelerators in Earth’s surface laboratories,including the Beijing Radioactive Ion beam Facility,as well as other scientifc platforms at home and abroad.This research covered nuclear theories,numerical models,direct measurements,indirect measurements,and other novel approaches,achieving great interdisciplinary research results,with high-level academic publications and signifcant international impacts.This article reviews the above research and predicts future developments.
基金Supported by National Natural Science Foundation of China(11565020)the Counterpart Foundation of Sanya(2016PT43)+2 种基金the Special Foundation of Science and Technology Cooperation for Advanced Academy and Regional of Sanya(2016YD28)the Scientific Research Starting Foundation for 515 Talented Project of Hainan Tropical Ocean University(RHDRC201701)the Natural Science Foundation of Hainan Province(114012)
文摘Based on the relativistic theory of superstrong magnetic fields（SMF）, by using three models those of Lai（LD）, Fushiki（FGP）, and our own（LJ）, we investigate the influence of SMFs due to strong electron screening（SES） on the nuclear reaction 23Mg（p,γ） 24Al in magnetars. In a relatively low density environment（e.g., ρ7 〈0.01）and 1 〈 B12 〈 102, our screening rates are in good agreement with those of LD and FGP. However, in relatively high magnetic fields（e.g., B12 〉102）, our reaction rates can be 1.58 times and about three orders of magnitude larger than those of FGP and LD, respectively（B12, ρ7 are in units of 1012G, 107 g cm-3）. The significant increase of strong screening rate can imply that more 23Mg will escape from the Ne-Na cycle due to SES in a SMF. As a consequence,the next reaction, 24Al（＋β, ν） 24Mg, will produce more 24Mg to participate in the Mg-Al cycle. Thus, it may lead to synthesis of a large amount of A〉20 nuclides in magnetars.
基金Supported by National Natural Science Foundation of China(NSFC) Projects (No.11075034)
文摘We study in the framework of the Langevin model the influence of initial excitation energy(E*) of Hg compound nuclei(CNs) on the sensitivity of the excitation energy at scission(Esc*) to the nuclear friction strength(β).It is shown that the sensitivity is enhanced substantially with increasing E*.Moreover,we find that the significant sensitivity of Esc* to β at high E*is little affected by a marked difference in the neutron-to-proton ratio of a CN and in its size and fissility.Our findings suggest that,on the experimental side,a measurement of Esc* in energetic proton-induced spallation reactions can provide not only a sensitive but also a robust probe of nuclear dissipation in fission of highly excited nuclei.Further development of a suitable approach to spallation reaction is discussed.
文摘The theoretical cross section calculations for the astrophysical p process are needed because most of the related reactions are technically very difficult to be measured in the laboratory. Even if the reaction was measured,most of the measured reactions have been carried out at the higher energy range from the astrophysical energies.Therefore, almost all cross sections needed for p process simulation have to be theoretically calculated or extrapolated to the astrophysical energies.^(112)Sn(α,γ)^(116)Te is an important reaction for the p process nucleosynthesis. The theoretical cross section of ^(112)Sn(α,γ)^(116)Te reaction was investigated for different global optical model potentials,level density, and strength function models at the astrophysically interested energies. Astrophysical S factors were calculated and compared with experimental data available in the EXFOR database. The calculation with the optical model potential of the dispersive model by Demetriou et al., and the back-shifted Fermi gas level density model and Brink-Axel Lorentzian strength function model best served to reproduce experimental results at an astrophysically relevant energy region. The reaction rates were calculated with these model parameters at the p process temperature and compared with the current version of the reaction rate library Reaclib and Starlib.
