The neutron richness of the light charged particles emitted out of the fission plane in heavy ion reactions has been experimentally investigated via the production of A=3 mirror nuclei in ^(86)Kr+^(nat)Pb reactions at...The neutron richness of the light charged particles emitted out of the fission plane in heavy ion reactions has been experimentally investigated via the production of A=3 mirror nuclei in ^(86)Kr+^(nat)Pb reactions at 25 MeV/u.The energy spectra and angular distributions of triton(t)and ^(3)He in coincidence with two fission fragments are measured with the Compact Spectrometer for Heavy IoN Experiment(CSHINE).The energy spectrum of ^(3)He is observed harder than that of triton in the fission events,in accordance with the phenomena reported as“^(3)He-puzzle”in inclusive measurements.With a data-driven energy spectrum peak cut scenario,it is observed that the yield ratio R(t∕^(3)He)increases with the angle to the fission plane,showing an enhancement of neutron-rich particle emission from out-of-fission-plane.A qualitative comparison with the transport model calculations suggests that this observation may serve as a new probe for the nuclear symmetry energy.展开更多
The internal pressure within fission gas bubbles(FGBs)in irradiated nuclear fuels drives mechanical interactions with the surrounding fuel skeleton.To investigate the micromechanical stress fields in irradiated nuclea...The internal pressure within fission gas bubbles(FGBs)in irradiated nuclear fuels drives mechanical interactions with the surrounding fuel skeleton.To investigate the micromechanical stress fields in irradiated nuclear fuels containing pressurized FGBs,a mechanical constitutive model for the equivalent solid of FGBs was developed and validated.This model was based on the modified Van der Waals equation,incorporating the effects of surface tension.Using this model,the micromechanical fields in irradiated U-10Mo fuels with randomly distributed FGBs were calculated during uniaxial tensile testing via the finite element(FE)method.The macroscopic elastic constants of the irradiated U-10Mo fuels were then derived using homogenization theory,and the influences of bubble pressure,bubble size,and porosity on these constants were examined.Results show that adjacent FGBs exhibit mechanical interactions,which leads to distinct stress concentrations in the surrounding fuel skeleton.The macroscopic elastic constants of irradiated U-10Mo fuels decrease with increasing the macroscopic porosity,which can be quantitatively described by the Mori-Tanaka model.In contrast,bubble pressure and size have negligible effects on these constants.展开更多
The Yangchuling porphyry W-Mo deposit(YPWD),located in the Jiangnan porphyryskarn tungsten ore belt,is one of the most important and large-scale porphyry W-Mo deposits in South China.While previous zircon U-Pb and mol...The Yangchuling porphyry W-Mo deposit(YPWD),located in the Jiangnan porphyryskarn tungsten ore belt,is one of the most important and large-scale porphyry W-Mo deposits in South China.While previous zircon U-Pb and molybdenite Re-Os data suggest that Yangchuling WMo ore bodies formed almost simultaneously with granodiorite and monzogranitic porphyry at~150–144 Ma,their post emplacement history remains poorly understood,making their preservation status at depth uncertain.In this paper,new zircon and apatite(U-Th)/He and apatite fission track(ZHe,AHe and AFT,respectively)data of one hornfels and five intrusive rocks from a 1000-meter borehole are presented.These,together with new inverse thermal history models and previous geochronological data,help elucidate the post-diagenetic exhumation history and preservation status of the Yangchuling porphyry W-Mo deposit.In general,ZHe and AHe ages decrease gradually from the near surface downwards and have relatively little intra-sample variation,ranging from 133 to 73Ma and 67 to 25 Ma,respectively.All four granodiorites yield similar AFT ages that range from 63 to 55 Ma with mean track lengths varying from 12.2±0.7 to 12.6±0.5μm.Thermal history modelling indicates that the Yangchuling ore district experienced slow,monotonic cooling since the Cretaceous.Age-depth relationships are interpreted as recording~3.7±0.8 km of Cretaceous-recent exhumation in response to regional extension throughout South China thought to have been driven by subduction retreat of the Paleo-Pacific Plate.Comparison of estimated net exhumation and previous metallogenic depth of~4–5 km suggests that W-Mo ore bodies could still exist at depths of up to~1.3±0.8 km relative to Earth surface in the YPWD region.Preservation of the YPWD is attributed to the limited amount of regional denudation during the Late Cretaceous and Cenozoic.展开更多
Intervertebral disc degeneration(IVDD)is the primary contributor to a range of spinal diseases.Dynamin-related protein 1(Drp1)-mediated mitochondrial fission has recently been identified as a new cause of nucleus pulp...Intervertebral disc degeneration(IVDD)is the primary contributor to a range of spinal diseases.Dynamin-related protein 1(Drp1)-mediated mitochondrial fission has recently been identified as a new cause of nucleus pulposus cell(NPC)death and IVDD,but the underlying mechanisms remain unclear.Although the effects of Drp1 phosphorylation in IVDD have been studied,it is currently unknown if small ubiquitin-like modifications(SUMOylation)of Drp1 regulate IVDD.This study aimed to investigate the functions and mechanisms of mitochondria-anchored protein ligase(MAPL),a mitochondrial SUMO E3 ligase,during IVDD progression.The expression of genes related to SUMOylation and mitochondrial dynamics in TNF-α-stimulated NPCs was analysed via RNA sequencing.展开更多
Prompt fission neutron spectra(PFNS)have a significant role in nuclear science and technology.In this study,the PFNS for^(239)Pu are evaluated using both differential and integral experimental data.A method that lever...Prompt fission neutron spectra(PFNS)have a significant role in nuclear science and technology.In this study,the PFNS for^(239)Pu are evaluated using both differential and integral experimental data.A method that leverages integral criticality benchmark experiments to constrain the PFNS data is introduced.The measured central values of the PFNS are perturbed by constructing a covariance matrix.The PFNS are sampled using two types of covariance matrices,either generated with an assumed correlation matrix and incorporating experimental uncertainties or derived directly from experimental reports.The joint Monte Carlo transport code is employed to perform transport simulations on five criticality benchmark assemblies by utilizing perturbed PFNS data.Extensive simulations result in an optimized PFNS that shows improved agreement with the integral criticality benchmark experiments.This study introduces a novel approach for optimizing differential experimental data through integral experiments,particularly when a covariance matrix is not provided.展开更多
The temporal and spatial evolution of the Ailao Shan-Red River(ASRR)fault zone,which serves as an important accommodation zone for the extrusion and escape of the Southeastern Tibetan Plateau,is crucial for analyzing ...The temporal and spatial evolution of the Ailao Shan-Red River(ASRR)fault zone,which serves as an important accommodation zone for the extrusion and escape of the Southeastern Tibetan Plateau,is crucial for analyzing the uplift and growth of the plateau.Based on the petrology and apatite fission track analysis,the tectonic history and active pattern of the ASRR fault zone since the middle Miocene are determined in this study.The ASRR fault zone exhibits 12-8Ma and 8-4 Ma rapid cooling phases since the middle Miocene.The 12-8 Ma and 8-4 Ma cooling may imply that the dextral movement of the ASRR fault zone presents a migration trend from northwest to southeast,accompanied by the weakening of the activity intensity,which is directly related to deformation processes,including extrusion boundary migration and active tectonic movements of the southeastern Tibetan Plateau,since the middle-late Miocene.展开更多
BACKGROUND Diabetic cognitive dysfunction(DCD)is one of the chronic complications of diabetes,but its mechanism is currently unknown.Studies have shown that mitochondrial fission mediated by calcium overload is an imp...BACKGROUND Diabetic cognitive dysfunction(DCD)is one of the chronic complications of diabetes,but its mechanism is currently unknown.Studies have shown that mitochondrial fission mediated by calcium overload is an important mechanism of DCD.Blocking calcium overload and restoring calcium homeostasis are key steps in treatment.Transient receptor potential melastatin 7(TRPM7)is a novel player in causing calcium overload.Our previous studies have shown that genetic silencing of TRPM7 in type 1 diabetic rats leads to significant improvements in cognitive function,but the specific mechanism remains unclear.Troxerutin,extracted from the flowers of Sophora japonica,is one of the derivatives of rutin and has been shown to have neuroprotective effects.However,its association with TRPM7 remains unclear.AIM To use animal and cellular models,we investigated whether TRPM7 mediated mitochondrial fission by upregulation of calcineurin(CaN)/dynamin-related protein 1(Drp1)ser637 in DCD,and whether Troxerutin improved DCD by inhibiting TRPM7-mediated mitochondrial division.METHODS In this study,we used db/db mice and hippocampal neuronal cell lines(HT22)treated with high-concentration glucose as our study subjects.We evaluated cognitive function using Morris water maze,novel object recognition tasks,and Nesting tests.We observed mitochondrial morphology using transmission electron microscopy and measured mitochondrial energy metabolism indicators using a spectrophotometer.We also detected mRNA and protein expression of TRPM7,CaN,p-Drp1^(ser637),caspase-3,B-cell lymphoma 2 associated X protein,and B-cell lymphoma 2 using quantitative real-time polymerase chain reaction,western blotting,and immunofluorescence.RESULTS In the db/db diabetic mice with cognitive dysfunction,as well as in hippocampal neurons exposed to high-concentration glucose,TRPM7 and CaN expression were upregulated,phosphorylated Drp1^(ser637)expression was downregulated,and mitochondrial fission was increased.By modulating(inhibiting or overexpressing)TRPM7,it was further validated that TRPM7 activates the CaN/Drp1^(ser637)pathway,resulting in an increase in mitochondrial fission and neuronal cell apoptosis.Troxerutin downregulated TRPM7/CaN/Drp1^(ser637),reduced mitochondrial fission,and improved DCD.CONCLUSION TRPM7 promotes mitochondrial fission via the CaN/Drp1^(ser637)pathway.Troxerutin improves mitochondrial function and reduces neuronal damage by inhibiting this pathway,suggesting TRPM7 as a potential therapeutic target for DCD.展开更多
Using the Skyrme density functional theory,potential energy surfaces of^(240)Pu with constraints on the axial quadrupole and octupole deformations(q_(20)and q_(30))were calculated.The volume-like and surface-like pair...Using the Skyrme density functional theory,potential energy surfaces of^(240)Pu with constraints on the axial quadrupole and octupole deformations(q_(20)and q_(30))were calculated.The volume-like and surface-like pairing forces,as well as a combination of these two forces,were used for the Hartree–Fock–Bogoliubov approximation.Variations in the least-energy fission path,fission barrier,pairing energy,total kinetic energy,scission line,and mass distribution of the fission fragments based on the different forms of the pairing forces were analyzed and discussed.The fission dynamics were studied based on the timedependent generator coordinate method plus the Gaussian overlap approximation.The results demonstrated a sensitivity of the mass and charge distributions of the fission fragments on the form of the pairing force.Based on the investigation of the neutron-induced fission of^(239)Pu,among the volume,mixed,and surface pairing forces,the mixed pairing force presented a good reproduction of the experimental data.展开更多
Panax ginseng(C.A.Mey.)has been traditionally employed in Korea and China to alleviate fatigue and digestive disorders.In particular,Korean red ginseng(KRG),derived from streamed and dried P.ginseng,is known for its a...Panax ginseng(C.A.Mey.)has been traditionally employed in Korea and China to alleviate fatigue and digestive disorders.In particular,Korean red ginseng(KRG),derived from streamed and dried P.ginseng,is known for its anti-aging and anti-inflammatory properties.However,its effects on benign prostatic hyperplasia(BPH),a representative aging-related disease,and the underlying mechanisms remain unclear.This study aims to elucidate the therapeutic effects of KRG on BPH,with a particular focus on mitochondrial dynamics,including fission and fusion processes.The effects of KRG on cell proliferation,apoptosis,and mitochondrial dynamics and morphology were evaluated in a rat model of testosterone propionate(TP)-induced BPH and TP-treated LNCaP cells,with mdivi-1 as a control.The results revealed that KRG treatment reduced the levels of androgen receptors(AR)and prostate-specific antigens in the BPH group.KRG inhibited cell proliferation by downregulating cyclin D and proliferating cell nuclear antigen(PCNA)levels,and it promoted apoptosis by increasing the ratio of B-cell lymphoma protein 2(Bcl-2)-associated X protein(Bax)to Bcl-2 expression.Notably,KRG treatment enhanced the phosphorylation of dynamin-related protein 1(DRP-1,serine 637)compared with that in the BPH group,which inhibited mitochondrial fission and led to mitochondrial elongation.This modulation of mitochondrial dynamics was associated with decreased cell proliferation and increased apoptosis.By dysregulating AR signaling and inhibiting mitochondrial fission through enhanced DRP-1(ser637)phosphorylation,KRG effectively reduced cell proliferation and induced apoptosis.These findings suggest that KRG’s regulation of mitochondrial dynamics offers a promising clinical approach for the treatment of BPH.展开更多
The Daqing Shan(DQS)located in the Yinshan-Yanshan Orogenic Belt plays an important role in the Mesozoic to Cenozoic evolution of the North China Craton.However,the cooling and exhumation history since the Cretaceous ...The Daqing Shan(DQS)located in the Yinshan-Yanshan Orogenic Belt plays an important role in the Mesozoic to Cenozoic evolution of the North China Craton.However,the cooling and exhumation history since the Cretaceous is still controversial.Integrating the apatite fission track(AFT)data in both this study and previous works,a three-stage exhumation history from Cretaceous to Neogene of the DQS is proposed.(1)The first stage is composed of the early exhumation during Early Cretaceous driven by the collision between the North China and Siberia cratons(ca.148-132 Ma)and the far-field effect of the subduction of the Pacific Plate(ca.132-114 Ma).(2)Due to the subsidence of the Hetao Basin and the subsequent compensation between the DQS and the Hetao Basin,the DQS experienced the second rapid exhumation from Early Eocene to Early Oligocene(ca.54-29 Ma).(3)Since the Late Miocene(ca.13.5 Ma),the third rapid cooling and exhumation of the DQS occurred due to the far-field effect of the uplift of the Tibetan Plateau and the subduction of the Pacific Plate.展开更多
Xiazhuang uranium ore field,located in the southern part of the Nanling Metallogenic Belt,is considered one of the largest granite-related U regions in South China.In this paper,we contribute new apatite fission track...Xiazhuang uranium ore field,located in the southern part of the Nanling Metallogenic Belt,is considered one of the largest granite-related U regions in South China.In this paper,we contribute new apatite fission track data and thermal history modeling to constrain the exhumation history and evaluate preservation potential of the Xiazhuang Uranium ore field.Nine Triassic outcrop granite samples collected from different locations of Xiazhuang Uranium ore field yield AFT ages ranging from 43 to 24 Ma with similar mean confined fission track lengths ranging from 11.8±2.0 to 12.9±1.9μm and Dpar values between 1.01 and 1.51μm.The robustness time-temperature reconstructions of samples from the hanging wall of Huangpi fault show that the Xiazhuang Uranium ore field experienced a time of monotonous and slow cooling starting from middle Paleocene to middle Miocene(~60-10 Ma),followed by relatively rapid exhumation in the late Miocene(~10-5 Ma)and nearly thermal stability in the Pliocene-Quaternary(~5-0 Ma).The amount of exhumation after U mineralization since the Middle Paleogene was estimated as~4.3±1.8 km according to the integrated thermal history model.Previous studies indicate that the ore-forming ages of U deposits in the Xiazhuang ore field are mainly before Middle Paleocene and the mineralization depths are more than 4.4±1.2 km.Therefore,the exhumation history since middle Paleocene plays important roles in the preservation of the Xiazhuang Uranium ore field.展开更多
This article explores the transformative potential of nanotechnology and MMs(memory metals)in enhancing the design and operation of nuclear reactors,encompassing both fission and fusion technologies.Nanotechnology,wit...This article explores the transformative potential of nanotechnology and MMs(memory metals)in enhancing the design and operation of nuclear reactors,encompassing both fission and fusion technologies.Nanotechnology,with its ability to engineer materials at the atomic scale,offers significant improvements in reactor safety,efficiency,and longevity.In fission reactors,nanomaterials enhance fuel rod integrity,optimize thermal management,and improve in-core instrumentation.Fusion reactors benefit from nanostructured materials that bolster containment and heat dissipation,addressing critical challenges in sustaining fusion reactions.The integration of SMAs(shape memory alloys),or MMs,further amplifies these advancements.These materials,characterized by their ability to revert to a pre-defined shape under thermal conditions,provide self-healing capabilities,adaptive structural components,and enhanced magnetic confinement.The synergy between nanotechnology and MMs represents a paradigm shift in nuclear reactor technology,promising a future of cleaner,more efficient,and safer nuclear energy production.This innovative approach positions the nuclear industry to meet the growing global energy demand while addressing environmental and safety concerns.展开更多
By using potential energy surface(PES)calculations in the three-dimensional space(β_(2),γ,β_(4))within the framework of the macroscopic-microscopic model,the fission trajectory and fission barrier for Z=118(Og),119...By using potential energy surface(PES)calculations in the three-dimensional space(β_(2),γ,β_(4))within the framework of the macroscopic-microscopic model,the fission trajectory and fission barrier for Z=118(Og),119,120 nuclei has been systematically investigated.The calculated PES includes macroscopic liquid-drop energy,microscopic shell correction and pairing correction.Taking the ^(294)Og176 nucleus as an example,we discuss the next closed shell after Z=82 and N=126 with the calculated Woods-Saxon single-particle levels.Then,the results of PES in ^(294)Og is illustrated from the(X,Y)scale to the(β_(2),γ)scale.Theγdegree of freedom reveals the shape evolution clearly during the fission process.The structure near the minimum and saddle point of the PES in the Z=118,119,120 nuclei is demonstrated simultaneously.Based on the potential energy curves,general trends of the evolution of the fission barrier heights and widths are also studied.The triaxial deformation in these superheavy mass regions plays a vital role in the first fission barrier,showing a significant reduction in both triaxial paths.In addition,the model-dependent fission barriers of proton-rich nuclei ^(295)Og,296119,and 297120 are analyzed briefly.Our studies could be valuable for synthesizing the superheavy new elements in the forthcoming HIAF and other facilities.展开更多
This article proposes to associate a Deuterium-Deuterium (D-D) fusion reactor with a PWR (fission Pressurized Water Reactor) in a hybrid reactor. Even if the mechanical gain (Q factor) of the D-D fusion reactor is bel...This article proposes to associate a Deuterium-Deuterium (D-D) fusion reactor with a PWR (fission Pressurized Water Reactor) in a hybrid reactor. Even if the mechanical gain (Q factor) of the D-D fusion reactor is below the unity and consequently consumes more energy than it supplies, due to the high energy amplification factor of the PWR fission reactor, the global yield is widely superior to 1. As the energy supplied by the fusion reactor is relatively low and as the neutrons supplied are mainly issued from D-D fusions (at 2.45 MeV), the problems of heat flux and neutrons damage connected with materials, as with D-T fusion reactors are reduced. Of course, there is no need to produce Tritium with this D-D fusion reactor. This type of reactor is able to incinerate any mixture of natural Uranium, natural Thorium and depleted Uranium (waste issued from enrichment plants), with natural Thorium being the best choice. No enriched fuel is needed. So, this type of reactor could constitute a source of energy for several thousands of years because it is about 90 more efficient than a standard fission reactor, such as a PWR or a Candu one, by extracting almost completely the energy from the fertile materials U238 and Th232. For the fission part, PWR technology is mature. For the fusion part, it is based on a reasonable hypothesis done on present Stellarators projects. The working of this reactor is continuous, 24 hours a day. In this paper, it will be targeted a reactor able to provide net electric power of about 1400 MWe, as a big fission power plant.展开更多
Photofission fragments mass yield for^(232)Th,^(234;238) U,^(237) Np, and^(239;240;242) Pu isotopes are investigated.The calculations are done using a developed approach based on Gorodisskiy's phenomenological for...Photofission fragments mass yield for^(232)Th,^(234;238) U,^(237) Np, and^(239;240;242) Pu isotopes are investigated.The calculations are done using a developed approach based on Gorodisskiy's phenomenological formalism. The Gorodisskiy's method is developed to be applied for the neutron-induced fission. Here we revised it for application to photofission. The effect of emitted neutron prior to fission on the fission fragment mass yields has also been studied. The peak-to-valley ratio is extracted for the240 Pu isotope as a function of energy. Obtained results of the present formalism are compared with the available experimental data. Satisfactory agreement is achieved between the results of present approach and the experimental data.展开更多
Photofission enables a unique capability for the domain of non-chemical space propulsion. An ultra-intense laser enables the capacity to induce nuclear fission through the development of bre- msstrahlung photons. A fu...Photofission enables a unique capability for the domain of non-chemical space propulsion. An ultra-intense laser enables the capacity to induce nuclear fission through the development of bre- msstrahlung photons. A fundamental architecture and performance analysis of a photofission pulsed space propulsion system through the operation of an ultra-intense laser is presented. A historical perspective of previous conceptual nuclear fission propulsion systems is addressed. These applications use neutron derived nuclear fission;however, there is inherent complexity that has precluded further development. The background of photofission is detailed. The conceptual architecture of photofission pulsed space propulsion and fundamental performance parameters are established. The implications are the energy source and ultra-intense laser can be situated far remote from the propulsion system. Advances in supporting laser technologies are anticipated to increase the potential for photofission pulsed space propulsion. The fundamental performance analysis of the photofission pulsed space propulsion system indicates the architecture is feasible for further evaluation.展开更多
Project New Orion entails a pulsed nuclear space propulsion system that utilizes photofission through the implementation of an ultra-intense laser. The historical origins derive from the endeavors of Project Orion, wh...Project New Orion entails a pulsed nuclear space propulsion system that utilizes photofission through the implementation of an ultra-intense laser. The historical origins derive from the endeavors of Project Orion, which utilized thermonuclear devices to impart a considerable velocity increment on the respective spacecraft. The shear magnitude of Project Orion significantly detracts from the likelihood of progressive research development testing and evaluation. Project New Orion incorporates a more feasible pathway for the progressive research development testing and evaluation of the pulsed nuclear space propulsion system. Photofission through the application of an ultra-intense laser enables a much more controllable and scalable nuclear yield. The energy source for the ultra-intense laser is derived from a first stage liquid hydrogen and liquid oxygen chemical propulsion system. A portion of the thermal/kinetic energy of the rocket propulsive fluid is converted to electrical energy through a magneto-hydrodynamic generator with cryogenic propellant densification for facilitating the integral superconducting magnets. Fundamental analysis of Project New Orion demonstrates the capacity to impart a meaningful velocity increment through ultra-intense laser derived photofission on a small spacecraft.展开更多
The capture and fission analysis of heavy ion induced fusion reactions leading to the formation of Z=107-111 superheavy nuclei has been carried out.Attempts have been made to analyze the synthesis traits,such as excit...The capture and fission analysis of heavy ion induced fusion reactions leading to the formation of Z=107-111 superheavy nuclei has been carried out.Attempts have been made to analyze the synthesis traits,such as excitation functions,formation probabilities,barrier characteristics etc.The l-summed Wong model provides a decent description of available data on capture(σCap)and fusion-fission(σff)cross-sections and hence is exploited to make relevant predictions for future experiments.The capture and fusion-fission excitation functions are predicted for the least explored region of superheavy nuclei(SHN)i.e.Z=107-111.The role of massasymmetry(η),Coulomb factor(ZPZT)deformation and orientations,Businari-Gallone massasymmetry(αBG)fission barrier(Bf)etc is duly explored.The present study concludes that the mass-asymmetric reactions involving 24Mg,30Si,and 36S projectiles are preferred for the synthesis of unknown isotopes of Z=107-111.Alternatively,the doubly magic 48Ca-projectile also provides a competing alternative to produce neutron-rich isotopes of the abovementioned SHN.展开更多
Based on interpretations of the apatite fission track analysis data for 10 outcrop samples and forward modeling of confined fission track length distributions, the thermal history of rocks in the Shiwandashan basin ...Based on interpretations of the apatite fission track analysis data for 10 outcrop samples and forward modeling of confined fission track length distributions, the thermal history of rocks in the Shiwandashan basin and its adjacent area, southern China, has been qualitatively and semi quantitatively studied. The results reflect several features of the thermal history. Firstly, all the samples have experienced temperatures higher than 60-70 ℃. Secondly, the time that the basement strata (T 1 b ) on the northwestern side of the Shiwandashan basin were uplifted and exhumed to the unannealed upper crust (with a paleogeotemperature of below 60-70 ℃) is much earlier than the basement rocks ( γ 1 5) on the southeastern side of the basin. Thirdly, the thermal history of samples from the basin can be divided into six stages, i.e., the fast burial and heating stage (220-145 Ma), the transient cooling stage (145-135 Ma), the burial and heating stage (135-70 Ma), the rapid cooling stage (70-50 Ma), the relatively stable stage (50-20 Ma) and another rapid cooling stage (20 Ma to present).展开更多
Erperimental method to measure the prompt neutron spectra of 238U fissioninduced by fast neutrons has been developed at HI-13 Tandem Van de Grab Accelerator Laboratory of CIAE. These techniques employ a multi-segment ...Erperimental method to measure the prompt neutron spectra of 238U fissioninduced by fast neutrons has been developed at HI-13 Tandem Van de Grab Accelerator Laboratory of CIAE. These techniques employ a multi-segment fission chamberand tab liquid scintillator neutron detectors. TOF (time of flight) techniques are usedfor prilnny neutrons to select the fission evellts induced by monoenergetic neutronfrom 'H(d, n) reactions instead of breakup neutrons from 'H(d, up) reactions. Thefission neutron TOF spectra are measured in coincidence with the fission fragmellts todistinguish fission neutrons from other secondals neutrons. The method perests measurements to a forly good accuracy under large neutron and gamma ray baCkgroulld.The tecboques are described and experimelltal spectra are presented.展开更多
基金the National Natural Science Foundation of China(Nos.12205160,11961131010,11961141004,and 11965004)by the Ministry of Science and Technology of China(Nos.2022YFE0103400 and 2020YFE0202001)+2 种基金by the Polish National Science Center(No.2023/49/B/ST2/01294)This work is also supported by Initiative Scientific Research Program and the Center of High Performance Computing of Tsinghua Universitythe Heavy Ion Research Facility at Lanzhou(HIRFL).
文摘The neutron richness of the light charged particles emitted out of the fission plane in heavy ion reactions has been experimentally investigated via the production of A=3 mirror nuclei in ^(86)Kr+^(nat)Pb reactions at 25 MeV/u.The energy spectra and angular distributions of triton(t)and ^(3)He in coincidence with two fission fragments are measured with the Compact Spectrometer for Heavy IoN Experiment(CSHINE).The energy spectrum of ^(3)He is observed harder than that of triton in the fission events,in accordance with the phenomena reported as“^(3)He-puzzle”in inclusive measurements.With a data-driven energy spectrum peak cut scenario,it is observed that the yield ratio R(t∕^(3)He)increases with the angle to the fission plane,showing an enhancement of neutron-rich particle emission from out-of-fission-plane.A qualitative comparison with the transport model calculations suggests that this observation may serve as a new probe for the nuclear symmetry energy.
基金National Natural Science Foundation of China(12135008,12132005)。
文摘The internal pressure within fission gas bubbles(FGBs)in irradiated nuclear fuels drives mechanical interactions with the surrounding fuel skeleton.To investigate the micromechanical stress fields in irradiated nuclear fuels containing pressurized FGBs,a mechanical constitutive model for the equivalent solid of FGBs was developed and validated.This model was based on the modified Van der Waals equation,incorporating the effects of surface tension.Using this model,the micromechanical fields in irradiated U-10Mo fuels with randomly distributed FGBs were calculated during uniaxial tensile testing via the finite element(FE)method.The macroscopic elastic constants of the irradiated U-10Mo fuels were then derived using homogenization theory,and the influences of bubble pressure,bubble size,and porosity on these constants were examined.Results show that adjacent FGBs exhibit mechanical interactions,which leads to distinct stress concentrations in the surrounding fuel skeleton.The macroscopic elastic constants of irradiated U-10Mo fuels decrease with increasing the macroscopic porosity,which can be quantitatively described by the Mori-Tanaka model.In contrast,bubble pressure and size have negligible effects on these constants.
基金supported by the National Natural Science Foundation of China(Nos.42162013,42002095)the Foundation of State Key Laboratory of Nuclear Resources and Environment(Nos.2022NRE34,NRE2021-01)+1 种基金Jiangxi Provincial Natural Science Foundation(Nos.20242BAB26048,20242BAB25178)Fund of National Key Laboratory of Science and Technology on Remote Sensing Information and imagery Analysis,Beijing Research Institute of Uranium Geology(No.6142A01210405)。
文摘The Yangchuling porphyry W-Mo deposit(YPWD),located in the Jiangnan porphyryskarn tungsten ore belt,is one of the most important and large-scale porphyry W-Mo deposits in South China.While previous zircon U-Pb and molybdenite Re-Os data suggest that Yangchuling WMo ore bodies formed almost simultaneously with granodiorite and monzogranitic porphyry at~150–144 Ma,their post emplacement history remains poorly understood,making their preservation status at depth uncertain.In this paper,new zircon and apatite(U-Th)/He and apatite fission track(ZHe,AHe and AFT,respectively)data of one hornfels and five intrusive rocks from a 1000-meter borehole are presented.These,together with new inverse thermal history models and previous geochronological data,help elucidate the post-diagenetic exhumation history and preservation status of the Yangchuling porphyry W-Mo deposit.In general,ZHe and AHe ages decrease gradually from the near surface downwards and have relatively little intra-sample variation,ranging from 133 to 73Ma and 67 to 25 Ma,respectively.All four granodiorites yield similar AFT ages that range from 63 to 55 Ma with mean track lengths varying from 12.2±0.7 to 12.6±0.5μm.Thermal history modelling indicates that the Yangchuling ore district experienced slow,monotonic cooling since the Cretaceous.Age-depth relationships are interpreted as recording~3.7±0.8 km of Cretaceous-recent exhumation in response to regional extension throughout South China thought to have been driven by subduction retreat of the Paleo-Pacific Plate.Comparison of estimated net exhumation and previous metallogenic depth of~4–5 km suggests that W-Mo ore bodies could still exist at depths of up to~1.3±0.8 km relative to Earth surface in the YPWD region.Preservation of the YPWD is attributed to the limited amount of regional denudation during the Late Cretaceous and Cenozoic.
基金supported by National Natural Science Foundation of China(82272549,82472505,and 82472498)National key Research and Development plan,Ministry of Science and Technology of the People’s Republic of China(2022YFC2407203)+2 种基金the Young Health Talents of Shanghai Municipal Health Commission,China(2022YQ011)China Medical Education Association(3030537245)The Youth Talent Project of Huashan Hospital(30302164006).
文摘Intervertebral disc degeneration(IVDD)is the primary contributor to a range of spinal diseases.Dynamin-related protein 1(Drp1)-mediated mitochondrial fission has recently been identified as a new cause of nucleus pulposus cell(NPC)death and IVDD,but the underlying mechanisms remain unclear.Although the effects of Drp1 phosphorylation in IVDD have been studied,it is currently unknown if small ubiquitin-like modifications(SUMOylation)of Drp1 regulate IVDD.This study aimed to investigate the functions and mechanisms of mitochondria-anchored protein ligase(MAPL),a mitochondrial SUMO E3 ligase,during IVDD progression.The expression of genes related to SUMOylation and mitochondrial dynamics in TNF-α-stimulated NPCs was analysed via RNA sequencing.
基金supported by the National Natural Science Foundation of China(No.12347126)。
文摘Prompt fission neutron spectra(PFNS)have a significant role in nuclear science and technology.In this study,the PFNS for^(239)Pu are evaluated using both differential and integral experimental data.A method that leverages integral criticality benchmark experiments to constrain the PFNS data is introduced.The measured central values of the PFNS are perturbed by constructing a covariance matrix.The PFNS are sampled using two types of covariance matrices,either generated with an assumed correlation matrix and incorporating experimental uncertainties or derived directly from experimental reports.The joint Monte Carlo transport code is employed to perform transport simulations on five criticality benchmark assemblies by utilizing perturbed PFNS data.Extensive simulations result in an optimized PFNS that shows improved agreement with the integral criticality benchmark experiments.This study introduces a novel approach for optimizing differential experimental data through integral experiments,particularly when a covariance matrix is not provided.
基金supported by the National Natural Science Foundation of China(Grant Nos.41530963,42406077)the Shandong Provincial Natural Science Foundation,China(Grant No.ZR2022QD087)the National Natural Science Foundation of China(Grant Nos.42376060,41176038)。
文摘The temporal and spatial evolution of the Ailao Shan-Red River(ASRR)fault zone,which serves as an important accommodation zone for the extrusion and escape of the Southeastern Tibetan Plateau,is crucial for analyzing the uplift and growth of the plateau.Based on the petrology and apatite fission track analysis,the tectonic history and active pattern of the ASRR fault zone since the middle Miocene are determined in this study.The ASRR fault zone exhibits 12-8Ma and 8-4 Ma rapid cooling phases since the middle Miocene.The 12-8 Ma and 8-4 Ma cooling may imply that the dextral movement of the ASRR fault zone presents a migration trend from northwest to southeast,accompanied by the weakening of the activity intensity,which is directly related to deformation processes,including extrusion boundary migration and active tectonic movements of the southeastern Tibetan Plateau,since the middle-late Miocene.
基金Supported by the Natural Science Foundation of Hebei Province,No.H2021206187 and No.H2021206452.
文摘BACKGROUND Diabetic cognitive dysfunction(DCD)is one of the chronic complications of diabetes,but its mechanism is currently unknown.Studies have shown that mitochondrial fission mediated by calcium overload is an important mechanism of DCD.Blocking calcium overload and restoring calcium homeostasis are key steps in treatment.Transient receptor potential melastatin 7(TRPM7)is a novel player in causing calcium overload.Our previous studies have shown that genetic silencing of TRPM7 in type 1 diabetic rats leads to significant improvements in cognitive function,but the specific mechanism remains unclear.Troxerutin,extracted from the flowers of Sophora japonica,is one of the derivatives of rutin and has been shown to have neuroprotective effects.However,its association with TRPM7 remains unclear.AIM To use animal and cellular models,we investigated whether TRPM7 mediated mitochondrial fission by upregulation of calcineurin(CaN)/dynamin-related protein 1(Drp1)ser637 in DCD,and whether Troxerutin improved DCD by inhibiting TRPM7-mediated mitochondrial division.METHODS In this study,we used db/db mice and hippocampal neuronal cell lines(HT22)treated with high-concentration glucose as our study subjects.We evaluated cognitive function using Morris water maze,novel object recognition tasks,and Nesting tests.We observed mitochondrial morphology using transmission electron microscopy and measured mitochondrial energy metabolism indicators using a spectrophotometer.We also detected mRNA and protein expression of TRPM7,CaN,p-Drp1^(ser637),caspase-3,B-cell lymphoma 2 associated X protein,and B-cell lymphoma 2 using quantitative real-time polymerase chain reaction,western blotting,and immunofluorescence.RESULTS In the db/db diabetic mice with cognitive dysfunction,as well as in hippocampal neurons exposed to high-concentration glucose,TRPM7 and CaN expression were upregulated,phosphorylated Drp1^(ser637)expression was downregulated,and mitochondrial fission was increased.By modulating(inhibiting or overexpressing)TRPM7,it was further validated that TRPM7 activates the CaN/Drp1^(ser637)pathway,resulting in an increase in mitochondrial fission and neuronal cell apoptosis.Troxerutin downregulated TRPM7/CaN/Drp1^(ser637),reduced mitochondrial fission,and improved DCD.CONCLUSION TRPM7 promotes mitochondrial fission via the CaN/Drp1^(ser637)pathway.Troxerutin improves mitochondrial function and reduces neuronal damage by inhibiting this pathway,suggesting TRPM7 as a potential therapeutic target for DCD.
基金supported by the National Key R&D Program of China(No.2022YFA1602000)National Natural Science Foundation of China(Nos.12275081,U2067205,11790325,and U1732138)the Continuous-support Basic Scientific Research Project。
文摘Using the Skyrme density functional theory,potential energy surfaces of^(240)Pu with constraints on the axial quadrupole and octupole deformations(q_(20)and q_(30))were calculated.The volume-like and surface-like pairing forces,as well as a combination of these two forces,were used for the Hartree–Fock–Bogoliubov approximation.Variations in the least-energy fission path,fission barrier,pairing energy,total kinetic energy,scission line,and mass distribution of the fission fragments based on the different forms of the pairing forces were analyzed and discussed.The fission dynamics were studied based on the timedependent generator coordinate method plus the Gaussian overlap approximation.The results demonstrated a sensitivity of the mass and charge distributions of the fission fragments on the form of the pairing force.Based on the investigation of the neutron-induced fission of^(239)Pu,among the volume,mixed,and surface pairing forces,the mixed pairing force presented a good reproduction of the experimental data.
基金supported by the 2021 Grant from the Korean Society of Ginseng。
文摘Panax ginseng(C.A.Mey.)has been traditionally employed in Korea and China to alleviate fatigue and digestive disorders.In particular,Korean red ginseng(KRG),derived from streamed and dried P.ginseng,is known for its anti-aging and anti-inflammatory properties.However,its effects on benign prostatic hyperplasia(BPH),a representative aging-related disease,and the underlying mechanisms remain unclear.This study aims to elucidate the therapeutic effects of KRG on BPH,with a particular focus on mitochondrial dynamics,including fission and fusion processes.The effects of KRG on cell proliferation,apoptosis,and mitochondrial dynamics and morphology were evaluated in a rat model of testosterone propionate(TP)-induced BPH and TP-treated LNCaP cells,with mdivi-1 as a control.The results revealed that KRG treatment reduced the levels of androgen receptors(AR)and prostate-specific antigens in the BPH group.KRG inhibited cell proliferation by downregulating cyclin D and proliferating cell nuclear antigen(PCNA)levels,and it promoted apoptosis by increasing the ratio of B-cell lymphoma protein 2(Bcl-2)-associated X protein(Bax)to Bcl-2 expression.Notably,KRG treatment enhanced the phosphorylation of dynamin-related protein 1(DRP-1,serine 637)compared with that in the BPH group,which inhibited mitochondrial fission and led to mitochondrial elongation.This modulation of mitochondrial dynamics was associated with decreased cell proliferation and increased apoptosis.By dysregulating AR signaling and inhibiting mitochondrial fission through enhanced DRP-1(ser637)phosphorylation,KRG effectively reduced cell proliferation and induced apoptosis.These findings suggest that KRG’s regulation of mitochondrial dynamics offers a promising clinical approach for the treatment of BPH.
基金supported by the Major National Science and Technology Projects of China(No.2016ZX05034001-006)the National Natural Science Foundation of China(Nos.42072132,41202104,and 41572131)the China Geological Survey Projects(Nos.DD20190103 and DD20190711)。
文摘The Daqing Shan(DQS)located in the Yinshan-Yanshan Orogenic Belt plays an important role in the Mesozoic to Cenozoic evolution of the North China Craton.However,the cooling and exhumation history since the Cretaceous is still controversial.Integrating the apatite fission track(AFT)data in both this study and previous works,a three-stage exhumation history from Cretaceous to Neogene of the DQS is proposed.(1)The first stage is composed of the early exhumation during Early Cretaceous driven by the collision between the North China and Siberia cratons(ca.148-132 Ma)and the far-field effect of the subduction of the Pacific Plate(ca.132-114 Ma).(2)Due to the subsidence of the Hetao Basin and the subsequent compensation between the DQS and the Hetao Basin,the DQS experienced the second rapid exhumation from Early Eocene to Early Oligocene(ca.54-29 Ma).(3)Since the Late Miocene(ca.13.5 Ma),the third rapid cooling and exhumation of the DQS occurred due to the far-field effect of the uplift of the Tibetan Plateau and the subduction of the Pacific Plate.
基金the Foundation of State Key Laboratory of Nuclear Resources and Environment(Grant Nos.NRE2021-01,2022NRE34)the National Natural Science Foundation of China(Grant No.42162013)+1 种基金the Third Xinjiang Scientific Expedition Program(Grant No.2022xjkk1301)the Fund of National Key Laboratory of Science and Technology on Remote Sensing Information and imagery Analysis,Beijing Research Institute of Uranium Geology(Grant No.6142A01210405).
文摘Xiazhuang uranium ore field,located in the southern part of the Nanling Metallogenic Belt,is considered one of the largest granite-related U regions in South China.In this paper,we contribute new apatite fission track data and thermal history modeling to constrain the exhumation history and evaluate preservation potential of the Xiazhuang Uranium ore field.Nine Triassic outcrop granite samples collected from different locations of Xiazhuang Uranium ore field yield AFT ages ranging from 43 to 24 Ma with similar mean confined fission track lengths ranging from 11.8±2.0 to 12.9±1.9μm and Dpar values between 1.01 and 1.51μm.The robustness time-temperature reconstructions of samples from the hanging wall of Huangpi fault show that the Xiazhuang Uranium ore field experienced a time of monotonous and slow cooling starting from middle Paleocene to middle Miocene(~60-10 Ma),followed by relatively rapid exhumation in the late Miocene(~10-5 Ma)and nearly thermal stability in the Pliocene-Quaternary(~5-0 Ma).The amount of exhumation after U mineralization since the Middle Paleogene was estimated as~4.3±1.8 km according to the integrated thermal history model.Previous studies indicate that the ore-forming ages of U deposits in the Xiazhuang ore field are mainly before Middle Paleocene and the mineralization depths are more than 4.4±1.2 km.Therefore,the exhumation history since middle Paleocene plays important roles in the preservation of the Xiazhuang Uranium ore field.
文摘This article explores the transformative potential of nanotechnology and MMs(memory metals)in enhancing the design and operation of nuclear reactors,encompassing both fission and fusion technologies.Nanotechnology,with its ability to engineer materials at the atomic scale,offers significant improvements in reactor safety,efficiency,and longevity.In fission reactors,nanomaterials enhance fuel rod integrity,optimize thermal management,and improve in-core instrumentation.Fusion reactors benefit from nanostructured materials that bolster containment and heat dissipation,addressing critical challenges in sustaining fusion reactions.The integration of SMAs(shape memory alloys),or MMs,further amplifies these advancements.These materials,characterized by their ability to revert to a pre-defined shape under thermal conditions,provide self-healing capabilities,adaptive structural components,and enhanced magnetic confinement.The synergy between nanotechnology and MMs represents a paradigm shift in nuclear reactor technology,promising a future of cleaner,more efficient,and safer nuclear energy production.This innovative approach positions the nuclear industry to meet the growing global energy demand while addressing environmental and safety concerns.
基金Supported by the National Natural Science Foundation of China(Grant Nos.12205076 and 12047504)the China Postdoctoral Science Foundation(Grant No.2020M670012)the Launching Fund of Henan University of Technology(Grant No.2021BS047).
文摘By using potential energy surface(PES)calculations in the three-dimensional space(β_(2),γ,β_(4))within the framework of the macroscopic-microscopic model,the fission trajectory and fission barrier for Z=118(Og),119,120 nuclei has been systematically investigated.The calculated PES includes macroscopic liquid-drop energy,microscopic shell correction and pairing correction.Taking the ^(294)Og176 nucleus as an example,we discuss the next closed shell after Z=82 and N=126 with the calculated Woods-Saxon single-particle levels.Then,the results of PES in ^(294)Og is illustrated from the(X,Y)scale to the(β_(2),γ)scale.Theγdegree of freedom reveals the shape evolution clearly during the fission process.The structure near the minimum and saddle point of the PES in the Z=118,119,120 nuclei is demonstrated simultaneously.Based on the potential energy curves,general trends of the evolution of the fission barrier heights and widths are also studied.The triaxial deformation in these superheavy mass regions plays a vital role in the first fission barrier,showing a significant reduction in both triaxial paths.In addition,the model-dependent fission barriers of proton-rich nuclei ^(295)Og,296119,and 297120 are analyzed briefly.Our studies could be valuable for synthesizing the superheavy new elements in the forthcoming HIAF and other facilities.
文摘This article proposes to associate a Deuterium-Deuterium (D-D) fusion reactor with a PWR (fission Pressurized Water Reactor) in a hybrid reactor. Even if the mechanical gain (Q factor) of the D-D fusion reactor is below the unity and consequently consumes more energy than it supplies, due to the high energy amplification factor of the PWR fission reactor, the global yield is widely superior to 1. As the energy supplied by the fusion reactor is relatively low and as the neutrons supplied are mainly issued from D-D fusions (at 2.45 MeV), the problems of heat flux and neutrons damage connected with materials, as with D-T fusion reactors are reduced. Of course, there is no need to produce Tritium with this D-D fusion reactor. This type of reactor is able to incinerate any mixture of natural Uranium, natural Thorium and depleted Uranium (waste issued from enrichment plants), with natural Thorium being the best choice. No enriched fuel is needed. So, this type of reactor could constitute a source of energy for several thousands of years because it is about 90 more efficient than a standard fission reactor, such as a PWR or a Candu one, by extracting almost completely the energy from the fertile materials U238 and Th232. For the fission part, PWR technology is mature. For the fusion part, it is based on a reasonable hypothesis done on present Stellarators projects. The working of this reactor is continuous, 24 hours a day. In this paper, it will be targeted a reactor able to provide net electric power of about 1400 MWe, as a big fission power plant.
文摘Photofission fragments mass yield for^(232)Th,^(234;238) U,^(237) Np, and^(239;240;242) Pu isotopes are investigated.The calculations are done using a developed approach based on Gorodisskiy's phenomenological formalism. The Gorodisskiy's method is developed to be applied for the neutron-induced fission. Here we revised it for application to photofission. The effect of emitted neutron prior to fission on the fission fragment mass yields has also been studied. The peak-to-valley ratio is extracted for the240 Pu isotope as a function of energy. Obtained results of the present formalism are compared with the available experimental data. Satisfactory agreement is achieved between the results of present approach and the experimental data.
文摘Photofission enables a unique capability for the domain of non-chemical space propulsion. An ultra-intense laser enables the capacity to induce nuclear fission through the development of bre- msstrahlung photons. A fundamental architecture and performance analysis of a photofission pulsed space propulsion system through the operation of an ultra-intense laser is presented. A historical perspective of previous conceptual nuclear fission propulsion systems is addressed. These applications use neutron derived nuclear fission;however, there is inherent complexity that has precluded further development. The background of photofission is detailed. The conceptual architecture of photofission pulsed space propulsion and fundamental performance parameters are established. The implications are the energy source and ultra-intense laser can be situated far remote from the propulsion system. Advances in supporting laser technologies are anticipated to increase the potential for photofission pulsed space propulsion. The fundamental performance analysis of the photofission pulsed space propulsion system indicates the architecture is feasible for further evaluation.
文摘Project New Orion entails a pulsed nuclear space propulsion system that utilizes photofission through the implementation of an ultra-intense laser. The historical origins derive from the endeavors of Project Orion, which utilized thermonuclear devices to impart a considerable velocity increment on the respective spacecraft. The shear magnitude of Project Orion significantly detracts from the likelihood of progressive research development testing and evaluation. Project New Orion incorporates a more feasible pathway for the progressive research development testing and evaluation of the pulsed nuclear space propulsion system. Photofission through the application of an ultra-intense laser enables a much more controllable and scalable nuclear yield. The energy source for the ultra-intense laser is derived from a first stage liquid hydrogen and liquid oxygen chemical propulsion system. A portion of the thermal/kinetic energy of the rocket propulsive fluid is converted to electrical energy through a magneto-hydrodynamic generator with cryogenic propellant densification for facilitating the integral superconducting magnets. Fundamental analysis of Project New Orion demonstrates the capacity to impart a meaningful velocity increment through ultra-intense laser derived photofission on a small spacecraft.
基金financial support from the UGC-DAE Consortium for Scientific Research,F.No.UGC-DAE-CSR-KC/CRS/19/NP09/0920the INSPIRE-fellowship(grant no.DST/INSPIRE/03/2015/000199).
文摘The capture and fission analysis of heavy ion induced fusion reactions leading to the formation of Z=107-111 superheavy nuclei has been carried out.Attempts have been made to analyze the synthesis traits,such as excitation functions,formation probabilities,barrier characteristics etc.The l-summed Wong model provides a decent description of available data on capture(σCap)and fusion-fission(σff)cross-sections and hence is exploited to make relevant predictions for future experiments.The capture and fusion-fission excitation functions are predicted for the least explored region of superheavy nuclei(SHN)i.e.Z=107-111.The role of massasymmetry(η),Coulomb factor(ZPZT)deformation and orientations,Businari-Gallone massasymmetry(αBG)fission barrier(Bf)etc is duly explored.The present study concludes that the mass-asymmetric reactions involving 24Mg,30Si,and 36S projectiles are preferred for the synthesis of unknown isotopes of Z=107-111.Alternatively,the doubly magic 48Ca-projectile also provides a competing alternative to produce neutron-rich isotopes of the abovementioned SHN.
文摘Based on interpretations of the apatite fission track analysis data for 10 outcrop samples and forward modeling of confined fission track length distributions, the thermal history of rocks in the Shiwandashan basin and its adjacent area, southern China, has been qualitatively and semi quantitatively studied. The results reflect several features of the thermal history. Firstly, all the samples have experienced temperatures higher than 60-70 ℃. Secondly, the time that the basement strata (T 1 b ) on the northwestern side of the Shiwandashan basin were uplifted and exhumed to the unannealed upper crust (with a paleogeotemperature of below 60-70 ℃) is much earlier than the basement rocks ( γ 1 5) on the southeastern side of the basin. Thirdly, the thermal history of samples from the basin can be divided into six stages, i.e., the fast burial and heating stage (220-145 Ma), the transient cooling stage (145-135 Ma), the burial and heating stage (135-70 Ma), the rapid cooling stage (70-50 Ma), the relatively stable stage (50-20 Ma) and another rapid cooling stage (20 Ma to present).
文摘Erperimental method to measure the prompt neutron spectra of 238U fissioninduced by fast neutrons has been developed at HI-13 Tandem Van de Grab Accelerator Laboratory of CIAE. These techniques employ a multi-segment fission chamberand tab liquid scintillator neutron detectors. TOF (time of flight) techniques are usedfor prilnny neutrons to select the fission evellts induced by monoenergetic neutronfrom 'H(d, n) reactions instead of breakup neutrons from 'H(d, up) reactions. Thefission neutron TOF spectra are measured in coincidence with the fission fragmellts todistinguish fission neutrons from other secondals neutrons. The method perests measurements to a forly good accuracy under large neutron and gamma ray baCkgroulld.The tecboques are described and experimelltal spectra are presented.
